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Green chemistry— a Canadian perspective Green Chemistry C G Green Chemistry December 1999 G155 This journal is © The Royal Society of Chemistry 1999 anada prides itself as a clean country—full of forests, lakes and mountains. Tourism is a major industry in Canada and, because we have a small population, mostly crowded within a hundred miles of the U.S. border, our country is one of huge empty spaces where vacationers can enjoy ‘Wilderness Canada’.The reality, as with so many other idyllic views of our countries, is tempered by some unattractive realities. More than 10% of Canada’s exports are connected with mining (coal, nickel, copper, cobalt uranium, etc.). Our northern and coastal forests are exploited for both lumber and pulp. Our waters are harnessed for the production of electricity to such a degree that most Canadians call their electricity bill a hydro bill; the impacts on the ecosystem have been very significant, as evidenced by the La Grande hydroelectric generating site in northern Quebec. Because our country is resource-rich, even though we are aware that the resources are limited, green chemistry looks somewhat different through Canadian eyes.The two areas I would like to consider are the uses of green chemistry in resource industries and enhancements to green chemistry that can be achieved through the use of analytical chemistry. Here I freely admit to a bias. I am an analytical chemist. Throughout my career I have been involved with a number of environmental issues, including the Niagara River and its pollution by industries (remember Love Canal?) and a number of local pollution issues.So it is important to me that analytical chemistry be used to measure more than our failure to be stewards of the environment, but also to provide the means of C PHOTO: DIVINO MUCCIANTE, BROCK UNIVERSITYimproving that environment by following the principles that were lucidly outlined by Paul Anastas and Tracy Williamson.1 A little over a year ago, the Organization for Economic Co-operation and Development (OECD) held a workshop in Venice on ‘Sustainable Chemistry’. Problems arose from the difficulties that the delegates had trying to incorporate the perspective of the Bruntland Report2 on sustainability into the already established notion of green chemistry.The idea of sustainable chemistry creates a new set of problems.Green chemistry is, in my view, remains a better descriptor than sustainable chemistry. Extraction of non-renewable resources is, by its nature, not sustainable and so the notion of doing sustainable things with an unsustainable end sounds perverse. We no longer close down metal mines to allow the ‘veins’ of ores to regrow, as they did in the 16th Century, as our contribution to sustainability.How shall we present the case for green chemistry in resource industries? Elimination of toxic chemicals should be a goal of green chemistry in the mining industry. An example of the use of green chemistry principles was achieved in Ontario a number of years before green chemistry saw the light of day.INCO, the largest nickel producer in Canada, extracts nickel as sulfide from a huge deposit near Sudbury. In addition to the nickel sulfide, they also extract pyrrhotite, which was used as a fuel, since its oxidation is exothermic. Both these sulfides were roasted in air, generating huge amounts of SO2, which laid waste to Sudbury as a result of acidification of the entire area. An initial solution to the problem was to collect the waste gases and push them up an enormous chimney.It solved the problem for Sudbury, but it made the residents of the Ottawa River Valley upset, as the acidification reached further east and was spread over a larger area. A partial solution was achieved when INCO eliminated the pyrrhotite by flotation, increased the oxygen level of the oxidizing gas and collected the SO2 by-product, which it sold as sulfuric acid.The pyrrhotite, which, if left exposed, would be oxidized by bacteria to H2SO4 (the infamous ‘acid mine drainage’), was reburied under anoxic conditions so that the extent of acid mine drainage would be reduced. As a reduction in the release of harmful by-products, this green chemistry reduced Canada’s acid emissions by a significant percent.Consider the case of gold. Gold continues to be extracted using high concentrations of cyanide to form Au(CN)2 –. Storage of waste cyanide in ponds results in ground water infiltration, leakage from poorly constructed dams, etc. A number of other compounds form stable complexes with gold and could be used in place of cyanide, such as thiourea or thiocyanate.As the natural resources are used up in the world, chemists and biotechnologists are being asked to come up with innovative ways in which renewable resources can be used to replace non-renewable ones But there will continue to be a demand for some non-renewable resources. In my high school chemistry text, I remember clearly the figure that showed the extraction of copper from the deposits in Northern Ontario.Basically you filled a hole with copper sulfate solution, popped in a copper electrode in the solution and banged in a connector to the massive deposits of native copper and electrolyzed away until the copper boulder dissolved. What is the percentage copper in high-grade ore today? So C G G156 Green Chemistry December 1999 This journal is © The Royal Society of Chemistry 1999 1 P.T. Anastas and T. C. Williamson, Green Chemistry, American Chemical Society, Washington, D.C., 1996. 2 Our Common Future, World Commission on Environment and Development (the Bruntland Commission), Oxford University Press, Oxford, 1987.if we wish to make materials that use less resources today, we try to minimize the amount of raw material that is incorporated in the object.Analytical chemistry provides the means of ensuring that the material, be it a turbine blade or a valve for the domestic water tap, meets the purpose for which it was designed. In North America, ASTM provides standards for many types of alloys that are used by industries. As new materials are developed, new standards must be made to ensure fitness for purpose of these materials.In addition, process analytical chemistry is integral to the developments in new processes and materials. The authors of a recent paper that I read noted that a reaction, which was carried out in a melt, was subject to polymerization if a reaction proceeded seconds beyond an optimum time. Although the authors felt that timing was an issue, real time analysis for the undesirable by-product would very likely give a better and ‘greener’ process.Analytical chemistry must be involved with the development of new materials, where exquisite control is required for the production of new materials with high production values. It is central to the future of R&D in innovative technologies. At last summer’s ‘Green Chemistry and Engineering’ Conference in Washington, I raised these issues at the final plenary session. The chair suggested that the developers of new products should take their analytical chemist out for lunch. We know there is no free lunch when it comes to environmental protection. Green chemistry principles must be applied to resource industries and raw material use and by-product generation can be controlled by adherence to quality management criteria that are central to the thinking of the analytical chemist. Ian D. Brindle, Department of Chemistry, Brock University, St. Catharines, Ontario L2S 3A1, Canada November 1999 C G Green Chemistry December 1999 G157 This journal is © The Royal Society of Chemistry 1999

ISSN:1463-9262    

DOI:10.1039/a909909c

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

C G Green Chemistry December 1999 G159 This journal is © The Royal Society of Chemistry 1999 N E W S Potential for hemp as green fibre source According to Farmers Weekly (17 September 1999) hemp is set to become and important green crop for arable rotation because of growing demand for hemp fibre from existing and new markets. Cigarette paper production has traditionally consumed a lot of hemp fibre, but it is now also being used as an alternative to cotton waste and wood pulp to make a range of environmentally acceptable papers.The second new market with huge potential is for lightweight door panels for the automotive industry. Automotive manufacturers in Germany are particularly interested in using a hemp and flax fibre mixture to replace the short wood fibres and to provide added strength and a significant weight reduction.Gas-to-liquid technology Rentech Inc has signed a letter of intent with Oroboros AB, headquartered in Goteborg, Sweden, to negotiate a licence for a GTL plant that will convert industrial off gases from a Swedish steel works into clean alternative fuels. The steel facility currently generates around 27 M cu ft/day of off-gases that are now flared into the atmosphere.The flaring, which occurs daily, produces about 2000 tonnes/year of carbon dioxide, a greenhouse gas. By implementing Rentech’s GTL technology, the plant’s off-gases, a mixture of hydrogen and carbon monoxide, can be converted into clean usable products instead of being flared. The application of Rentech’s process to this one facility is estimated to reduce carbon dioxide emissions in Sweden by 200,000 tonnes/year.Oroboros plans to produce what it refers to as an Eco-Paraffin, a clean alternative fuel, from the GTL process. This fuel, also known as Fischer–Tropsch diesel, contains no sulfur or aromatic compounds. Moreover, based on an assessment by Oroboros, Eco-Paraffin may also have a lower production cost than other alternative fuels presently available in Sweden.Rentech Inc, the Denver-based holding company which developed and licenses a proprietary and patented process, gas-toliquid (GTL), for the conversion of gases, solid and liquid carbon bearing material into valuable liquid hydrocarbons. For further information see http://www.gastoliquids.com Biomass biodegradable solvent from… USANTEC Inc.and Archer Daniels Midland have signed an agreement to jointly develop and commercialize new markets for ethyl lactate, a biodegradable solvent made from corn. Under the auspices of this arrangement, all North American sales of ethyl lactate manufactured by Archer Daniels Midland will be handled under the umbrella of a strategic relationship between NTEC and Archer Daniels Midland.This product, already being shipped to several customers in the US, is sold under the ‘Versol’ brand name. Ethyl lactate is a high performance, environmentally friendly green solvent that can successfully replace hundreds of millions of pounds of toxic petroleum-based chemical compounds used in the world today. Ethyl lactate is 100% biodegradable: it simply decomposes into carbon dioxide and water.Archer Daniels Midland, based in Decatur, Illinois, is engaged in the business of procuring, transporting, storing, processing and merchandising agricultural commodities and products. For further information see http://www.admworld.com liquid fuel from… The HTU (Hydro Thermal Upgrading) process developed by Shell Nederland, Stork, Biofuel, TNO-MEP, Biomass Technology Group, and other bodies allows the production of green crude oil from biomass.The oil is intended for use as a traditional mineral oil fuel. The technology contributes to the government’s target of increasing the amount of energy generated from biomass. It involves the conversion of water and residual plant materials to a liquid crude oil at high temperature and pressure.The oil is more environmentally friendly than mineral oil because its formation and breakdown are overall carbon dioxide-neutral. polyesters from… Metabolix Inc. of Cambridge, Massachusetts, USA, has been awarded a European Patent describing the production of polyesters in plant crops. The polyesters, known as PHAs, can be used as thermoplastics in an extensive range of applications.In parallel, Metabolix has also developed energy efficient fermentation routes to convert plant derived feedstocks into aqueous based PHA coating compositions. The PHA polyester materials may also be readily broken down to useful chemicals providing an alternative environmentally attractive and economical route for the sustainable production of chemical intermediates.The European Patent No. 482 077 brings the number of patents issued or exclusively licensed to Metabolix for the production of plastics and chemicals from agricultural sources to a total of eleven. For further information see http://www.metabolix.com There is increasing demand for hemp as a source of fibreN E W S G160 Green Chemistry December 1999 This journal is © The Royal Society of Chemistry 1999 C G Genetic modification …in rubber production The International Rubber Research and Development Board (IRRDB) are advocating a policy of using genetic research and development to ensure future sustainable supplies of natural rubber.The Board also maintains that the technological excellence of natural rubber cannot currently be matched by synthetic rubber.The production of natural rubber is also seen to serve the interests of the global environment by reducing deforestation and carbon dioxide levels throughout the world. The fact that natural rubber production is being forced into areas with poorer climate and soil properties is cited as further reason for the use of genetic development of clones. …in agriculture Monsanto Chairman and Chief Executive Officer Robert Shapiro has urged Greenpeace leaders and other stakeholders to engage with the company in an open and constructive dialogue about the use of biotechnology in agriculture.Shapiro reaffirmed that Monsanto continues to be a strong proponent of modern biotechnology as a safe and important tool for helping farmers meet the world’s growing need for food and fibre in a more environmentally sustainable way.The exchange with Greenpeace leaders followed an announcement on 4 October 1999 by Monsanto that the company would not commercialize sterile seed technologies. Monsanto made the commitment in response to concerns of experts and stakeholders, including growers in developed countries, about the potential effect of gene protection systems in developing countries.For further information see http://www.monsanto.com Coatings systems for braided fuel hose Kaechele-Cama Latex GmbH, of Eichenzell, Germany, has developed an environment-friendly solvent-free adhesive and coating system for braided fuel hose used in automotive and other applications. The patented system, applied to the hose by immersion, is based on Neoprene polychloroprene elastomer by DuPont Dow Elastomers.Fuel hose for modern motors, whether diesel or petrol, is exposed to high temperatures, corrosive fluids and other aggressive conditions. To meet such tough requirements automotive engineers normally specify braided, coated rubber hose. Until now solvent-based primers were mainly used to bind the textile layers to the rubber in this type of hose.The adhesive force of these primers results from their etching effect on the rubber. Solvents which evaporate during the manufacturing process are known to have undesirable effects on the environment and on employees producing the hose manufacturers have therefore been developing solvent-free systems. KCL’s water-based adhesive and coating systems meet the automotive industry’s demanding requirements as well as current and foreseeable environmental protection regulations.The product’s cross-linking characteristics allow co-vulcanisation with the rubber of the hose itself. The KCL is not subject to gelling or clotting, even after extended stand times. Apart from the immersion process which is the usual one for hose production, the KCL system can also be applied by means of spraying or dipping.The silane business More than DM 500 M is to be invested by Degussa-Huels AG in its silane operations. By the beginning of 2002, capacity for production of sulfur-functional organosilanes is to be raised by two-thirds at a cost of DM 200 M. The major application for these compounds is in the rubber industry for production of green tyres.Capacity for chlorosilanes and organosilanes will be increased at a cost of DM 300 M, with the majority of the work due to be completed by 2002. The leading global producer of sulfurfunctional organosilanes, Degussa- Huels is the second largest producer of organosilanes and chlorosilanes. It is the leading European producer. Demand for the compounds in recent years has been greater than the rate of economic growth and this is expected to continue.In early 2000, capacity expansions for sulfurfunctional organosilanes are due to be brought onstream in Antwerp and Mobile, USA. A new production facility is due to be constructed in Antwerp. Further production capacity for organosilanes and chlorosilanes is to be added at the company’s facilities in Antwerp, Mobile and Rhinefelden.Phthalates in children’s toys We reported in a previous edition of Green Chemistry the background to the controversy over phthalates in children’s toys and the various calls for a ban on their use (Green Chem. 1999, 1, 102); we also reported the development of the Dutch Migration Test to measure phthalate migration.Now the European Commission has proposed an EU-wide ban on soft PVC teething toys for children under 3 years of age, after its Scientific Committee on Toxicity, Ecotoxicity and the Environment (CSTEE) concluded that the Dutch Migration Test showed ‘poor reproducibility’. Under the proposals other toys containing phthalates, but not intended for teething, would merely have to carry a warning to keep them out of the mouth.These proposals will now move to the Product Safety Emergencies Committee of the Member States. Following talks with the British Toy and Hobby Association, the UK Department of Trade and Industry has announced an immediate ban on teethers and teething rings containing phthalates. Greenpeace has welcomed the ban but feels that it should not be restricted to teething toys, while the European Council for Plasticisers and Intermediates (ECPI), which represents manufacturers of phthalates, has reacted angrily to the ban, calling it ‘totally unjustified’.Cleaner fuels …BP Amoco in Chicago BP Amoco intends to bring three grades of cleaner gasoline to Chicago, and that the resulting emissions reduction would be the equivalent of removing 70,500 cars from Chicago’s highways each day.The company reported that the announcement is a direct result of its ongoing partnership with General Motors Corp, through which the companies plan to offer consumers new choices for cleaner vehicles in the 21st century. BP Amoco announced that its first lower sulfur product offering in Chicago, its Crystal Clear Amoco Ultimate is available at Amoco locations in Chicago and Northwest Indiana.Further, the company announced it intends to provide lower sulfur gasoline in all three grades including unleaded regular in Chicago inGreen Chemistry December 1999 G161 This journal is © The Royal Society of Chemistry 1999 N E W S C G the spring of 2001. These fuels meet US EPA proposed sulfur requirements for year 2004 gasoline and will be available years ahead of that deadline.For further information see http://www.bpamoco.com …DynaMotive bio-oil technology DynaMotive Technologies Corp (DynaMotive) announced its corporate development strategy for the year 2000 as it commences commercial exploitation of its technologies. DynaMotive aims to early position its pyrolysis technology in its key markets of Europe, Latin America, the USA and Canada in the year 2000, and plans to develop permanent presence in these markets to support expansion efforts.In 1999, DynaMotive has consistently improved the efficiency of its BioOil production technology and has met all its technical development milestones. It is continuing to produce high grade oil from biomass and has developed engineering designs for scale up facilities. Furthermore, DynaMotive’s biomass oil has been tested successfully by various engine manufacturers in Europe and Canada.For example, DynaMotive has signed an agreement with Magellan Aerospace Corp business unit Orenda Aerospace of Mississauga, Ontario, to test DynaMotive BioOil as a clean fuel to generate ‘green’ power in their gas turbines.DynaMotive Technologies develops and markets environmental technologies that provide clean, competitive alternatives to traditional industrial processes. The BioOil division is commercializing a renewable energy technology that converts low value forest and agricultural waste into liquid BioOil. which can be used as a clean burning liquid fuel substitute to fossil fuels to generate green power in stationary diesel engines and gas turbines.BioOil can also be used as the raw material for a range of derivative products including fertilizers, air pollution control agents and special chemicals. For further information see http://www.dynamotive.com …platinum-containing fuel additives In another development, Clean Diesel Technologies has licensed the Johnson Matthey patents on ‘Continuously regenerating Technology’ which are based on the use of platinum-containing fuel additives in conjunction with a particulate filter.…CARB diesel A new cleaner-burning diesel fuel has been tested by Atlantic Richfield Co. (Arco) in the US. The tests took place one day after the federal (EPA) and Californian state (Californian Air Resources Board) regulators proposed new standards for cleaner emissions.Arco began developing cleaner gasoline for California which later served as a model for the 1996 mandated ultra-clean CARB unleaded. The adoption of CARB diesel has been credited with cleaning up the famous Los Angeles smog. There have been no emergency smog alerts this year for the first time in decades.However, the small number of diesel vehicles on the road still contribute a high proportion of the atmospheric pollution notably nitrogen oxides and particulates. The new diesel fuel ‘EC diesel’ (EC stands for emission control) has a lower sulfur level and reduced nitrogen emissions compared to CARB diesel. Particulate emissions are 12% lower (Reuters News Service). MTBE The US Congress has a key opportunity now to fix a major flaw in US environmental policy and, starting with California, put US back on track toward cleaner air and safe drinking water, a Chevron executive told the World Fuels Conference.Patricia Woertz, president of Chevron Products Co, called for passage of a bill by Senator Diane Feinstein and Congressman Brian Bilbray which would start restoring flexibility to the rules for making reformulated gasoline and begin the process of eliminating or reducing the use of the gasoline blending chemical methyl tertiary butyl ether (MTBE).DuPont …Sustainable Growth Excellence Awards In 1999 DuPont made 12 awards of $5000 to teams of employees in the 10th annual Sustainable Growth Excellence Awards programme. The teams use the awards to make donations to external health, safety, environmental or social non-profit making organisations. Winning developments have included a significant improvement in the company’s ability to handle tetrafluoroethylene, which is highly explosive and used to make a range of fluoropolymers.Other winning developments included a Brazilian teams new use for a chemicals side stream which reduced costs by $3 M and generated $5 M in revenue.In Taiwan a team developed fast clarifier technology and improved quality of plant effluent by 15%. DuPont has declared an objective of achieving 25% of revenues from non-depletable raw materials by 2010. In 1998 less than 5% of its revenues came from renewable resources. The company is investing in producing chemicals from replaceable sources such as plants and microbes.Biotechnology will be a critical enabling technology. DuPont has built a world class position in biotechnology and molecular biology which complements its three existing strengths: engineering, chemistry and information science. So far this research has focused on improving the nutritional and health qualities of food. DuPont suggests a 3-point strategy for promoting biotechnology by chemical industry.Firstly, there needs to be an expansion of the biotechnology debate beyond the current genetically modified crops controversy. Secondly, public concerns must be addressed, and thirdly market realities and human needs must also being considered in the debate. DuPont’s industrial safety business is recording growth of 20% per year.…DuPont backs biotech A commitment to energy conservation and the use of biotechnology has been made by DuPont. It is aiming to obtain 10% of its energy requirements from renewable resources. It is also aiming to reduce its carbon emissions by 65%. Currently, under 5% of revenues come from carbohydrates and other nondepletable resources. The company aims to increase this to 25% within 10 years.It is using biotechnology in a wide range of sectors, including the use of plants as raw materials for production of polyester. Other technologies using microbes and bioprocesses are being developed. Sales by DuPont amounted to $24.767 bn in 1998 and the company expects a small but significant proportion of sales to come from biotechnology products within five years.By the end of 1999, the company hopes to have secured a partner for its pharmaceutical operations. Although a $600 M cut in capital expenditure for nylon production in Asia was has been announced, the company is still committed to this product and also to polyester.MTBE increases the oxygen content of gasoline, and is heavily used in 16 US states to meet oxygen levels mandated by the Clean Air Act Amendments of 1990.Although MTBE is national issue in the US, the bill focuses on improving the situation first in California, where overlapping state and federal rules mean that 70% of all gasoline sold has about 10% MTBE. Woertz said the bill would be a big step toward ultimately fixing MTBE problems elsewhere by helping California refiners meet Governor Gray Davis’s directive to remove it by the end of the year 2002.…California’s top air quality official has urged the US Congress not to force the State into replacing MTBE with ethanol. Michael Kenny has asked that instead they should eliminate the requirement under the 1990 Clean Air Act that all reformulated gasoline should contain 2% oxygen. This would allow California to phase out MTBE without having to increase petrol prices (Reuters News Service).…The EPA is to take measures to substantially reduce the use in reformulated gasolines of the oxygenate MTBE which has been found to be polluting groundwater in California and elsewhere. In April 1999, the Governor of California banned the use of MTBE in gasoline sold in the state by the end of 2002 and requested the EPA to grant the state a waiver from federal oxygenate requirements for reformulated gasolines.A timetable has been set for the gradual phase-out of MTBE to give refiners time to retrofit their plants to produce gasolines which would meet air quality standards without containing MTBE. Refinery modifications will involve significant amounts of capital.No studies to date have indicated that MTBE consumption presents a health risk to humans but its distinctive odour and taste make it detectable in water even at very low concentrations and there is ample evidence of its presence in many drinking water sources, presumably as the result of leaks in underground storage tanks. The US Clean Air Act Amendments in 1990 called for the gradual introduction of reformulated gasoline (RFG) in areas which the EPA considered to have unacceptable air quality.More stringent requirements are due to take effect in Phase II beginning in 2000. By 1999, the manufacture of MTBE by oil companies and other reached 269,000 bbl/day. The EPA mandates a minimum oxygen content in fuel of 1.8% per weight which corresponds to an MTBE concentration of about 11% volume.California Air Resources Board (CARB) does not require any minimum oxygen content in summer gas but imposes a 2.7% weight limit on the grounds that high oxygen content is associated with the increased nitrogen oxide emissions, especially in summer. If MTBE use is restricted and subsequently banned, specifications for FRG could theoretically be met by substituting ethanol or other, less well-known oxygenates for MTBE or, theoretically, without the use of any oxygenates.The National Research Council (NRC) panel concluded in May that the use of both ethanol and MTBE in RFG contributed little to reducing ozone. The EPA has proposed a rule, expected to be final by the end of 1999, calling for a 90% cut in US gasoline sulfur levels nationwide by 2004.The oil industry argues that reduction should be required only in areas of the country where it will make a difference in air quality and not nationwide. Catalysts …maleic anhydride Maleic anhydride catalyst capacity has been quadrupled at BP Amoco’s chemical complex at Green Lake, US. The new plant is due onstream in 4th quarter 1999. The expansion was needed to meet captive demand for maleic anhydride to manufacture 1,4-butanediol using a butane-to-maleic conversion.BP Amoco has pilot plants operating which produce acrylonitrile directly from propane and ammonia. BP Amoco currently produces acrylonitrile using propylene. …metallocene catalysts With a 140 kg/month production facility for metallocene catalysts at Soka, Kanto Chemical is the only producer in Japan.Output is supplied to the petrochemical sector. The company is planning to increase production of the catalysts. It is also developing new catalysts, including one based on a ruthenium complex together with a small amount of strong base which is used for highly selective hydrogenation. A high yield of alcohol is obtained from ketones and aldehydes using the novel catalyst.Another new catalyst contains an optically active ligand and is capable of producing large amounts for optically active alcohol at high purity. The new catalysts do not produce significant amounts of chlorine solvent N E W S C G G162 Green Chemistry December 1999 This journal is © The Royal Society of Chemistry 1999 or waste metal and are therefore environmentally friendly.The company anticipates that they will be used for the production of pharmaceuticals and fine chemicals. Brominated flame retardants The Dead Sea Bromine Group’s Flame Retardant Business unit has developed a range of non-halogenated flame retardants. The FR-20 series is based on surface-treated magnesium hydroxides and is intended for use in wire and cable applications and for nylons.The company is also undertaking research to develop its brominated flame retardants range. FR-245 [tris(tribromophenyl) cyanurate] has a bromine content of 67% and FR-1808 (brominated phenyl indane) has a bromine content of 73%. The flame retardants are environmentally-friendly and are especially effective in styrenics. FR-245 is also particularly light-stable. Both products comply with the German (Dioxin) Ordinance and EPA TSCA 40 766.25 Final Rule requirements.Dead Sea Bromine Group has raised its production capacity for FR-1025 [poly(pentabromobenzyl)acrylate] which is used as a flame retardant in engineering thermoplastics. In late 1999 it will launch the FR-300 series for PP applications. The FR-300 series is particularly suitable for flame retardant PP fibres.Aquilo wins BOC contract for nitrogen membrane The French gas separation equipment company Aquilo has been awarded a $3.5 M contract by BOC to supply a dozen small format membranes for the production of nitrogen from pressurized air. BOC will use these to adapt its existing nitrogen generators to the increasingly stringent requirements of customers.Nitrogen production using membranes is a low-energy, environmentally friendly process which is intended for in situ applications rather than for bottled gas production. The contract was negotiated in collaboration with Aquilo’s parent company Whatman, UK.C G Green Chemistry December 1999 G163 This journal is © The Royal Society of Chemistry 1999 N E W S Decolourable ink by Toshiba The prospect of more attractive recycled paper, cheaper as well as whiter, could be just around the corner thanks to a new type of decolourable ink which can be made to disappear from printed paper almost as quickly as it appears.Developed by Toshiba in Japan, the new ink will help simplify paper recycling; by making the ink disappear from the paper before it is recycled, it should be possible to circumvent the energy-intensive ink removal and bleaching stages involved in conventional recycling processes.The effect of the new ink is similar to that of commercial invisible inks, but the result is a much cleaner piece of paper which is free from the acid and base residues that interfere with recycling. The ink works by reversing the chemistry of the thermalsensitive paper used in fax machines.Fax paper is coated with a special layer containing a leuco dye and tiny capsules of a developer compound. These two components combine to produce the colour print when the paper is heated by a thermal print head in the fax machine, or when pressure is applied. Toshiba researchers are able to reverse this process by adding an eraser compound, cholic acid, to the ink formulation. To effect decolourisation, researchers either heat the paper or soak it in solvent which causes the cholic acid to lock onto the developer, breaking the hydrogen bonds attaching it to the dye.The ink costs about the same as colour toners used in copiers, and existing printing processes could be adapted to support recycling with little more than a change of ink, researchers claim. Powder coatings Powder coatings is generally an environmentally friendly technology offering zero VOC emissions.The greatest potential threat to health is the use of triglycidyl isocyanurate (TGIC). Until 1998 it was used as a crosslinker for exterior polyesters. The European Community has now classified it as a mutagenic, with a T(oxic) symbol.EMS Chemie has developed Primid b-hydroxyalkylamide as a substitute for TGIC. It can produce over 70,000 tonnes/year of polyester/Primid coatings. Other contenders include Uranox aliphatic oxirane and Araldite glycidyl ester from Ciba. Polyester/TGIC continues to account for 43% of the exterior powder coating market in Europe followed by polyester/Primid with 42% and Araldite with 10%.Polyurethanes account for 24% of the global market but just 4.5% in Europe. r Making good use of young energy According to The Independent (30 September 1999) a South African company has devised a clever method for exploiting the energy of children at play—a playpump which is powered by a children’s roundabout. The idea is due to an Afrikaner engineer and is being used by the Playpump company run by Trevor Field.The playpump can pump 1,400 litres of water an hour compared to 150 litres an hour using a conventional hand pump. The pump is low-maintenance and provides welcome respite to the mothers of the children who can see their children’s energy usefully exploited while making their own life a little easier. Soft-touch foams A cost-effective and environmentally friendly alternative to crosslinked PE foams has been launched by the Performance Foams Division of Dow Chemical Co for use in automotive material handling, touch-sensitive parts and military packaging. Known as Synergy Soft Touch Foams, they are made from low density polyethylene and Index ethylene-styrene interpolymers.The foams are resilient and strong. They can serve as insulators, shock absorbers and vibration dampeners.Three grades are available for use as dunnage or cushioning in packaging and as buoyancy or barrier components. Synergy Soft Touch Foams exceed industry standards for toughness and softness. The interpolymers are produced using Dow’s Insite technology. Other interpolymer materials available from Dow are Quash sound management foam and Envision foam laminate.Dow’s RapidRelease technology, that incorporates a patented CFC and HCFC free hydrocarbon blowing agent combined with accelerated curing systems, is used to produce the Synergy foams. Solvent trends …The demand for solvents has declined over the past decade due to a combination of environmental concerns and stricter legislation as well as weak European and Asian economies.The demand by 2001 is estimated at $4 bn. The trend from chlorinated solvents towards oxygenated solvents continues with the former predicted to decrease by 2.5%/year and the latter expected to increase by 2–3%/year. …In Japan in 1998 there was a 15.1% increase in the volume of solvents recycled. About 20% of the 206,000 tonnes recycled were chlorinated compounds. New battery technology Exide Corp, a global leader in the business of stored electrical energy, has entered into a preliminary agreement to acquire a controlling interest in Lion Compact Energy, a privately held company conducting research in dual-graphite battery technology that could dramatically advance the search for cleaner, less expensive and more efficient batteries.Lion Compact Energy has thus far produced several prototype batteries using graphite in different forms as the electrode material. The company estimates that, in full production, its graphite battery could produce more than three times the energy of today’s most advanced production batteries, with half the weight, occupying far less space, and at only one third the cost.Exide’s share of Lion Compact Energy will be acquired from the Michigan Molecular Institute. Exide Corp, with revenues of about $2.4 bn/year and operations in 19 countries, is the world’s largest manufacturer of automotive and industrial lead-acid batteries. For further information see http://www.exideworld.com CFC replacements A new unit for the manufacture of R134a (HCF 134a) has been brought on line by Xi’an Jinzhi Modern Chemical Industrial in China.R134a is a freon replacement which is currently consumed in China at a rate of 2000 tonnes/year. This is expected to rise to 5000 tonnes/year soon and new manufacturing capacity will be introduced to meet this increasing demand.N E W S C G …As the phase-out of the hydrochlorofluorocarbon foam blowing agent HCFC- 141b draws close, US producers have different strategies for relacements.Elf Atochem expect to rely on existing products while AlliedSignal and LaRoche may switch to the new non-ozone depleting agent HFC-245a. This new product is likely to have a high price however, and there are also concerns over its lack of availability. Two approved alternatives are HFC-134a and saturated C3-C6 hydrocarbons (Chemical and Engineering News, 31 May 1999, 77, 17).Cleaner syntheses …tert-butyl acetate Lyondell Chemical has begun commercial production of tert-butyl acetate (TBAc) using its new, proprietary process. This process uses acetic acid and either tertiary butyl alcohol or isobutylene as feedstock, and is significantly easier and cheaper than the existing ketene-based route, and yields a purer end product. It is being carried out for Lyondell by a toll production partner in Houston, Texas.Lyondell is the first commercial producer of TBAc in the US, and is selling it at less than $1/lb. Current capacity is over 22,000 tonnes/y (50 M lbs/year) and can easily be expanded. High production costs have previously limited the availability of TBAc.The leading producer is Wacker Chemie of Germany which is thought to have a world market share of over 50%. However, Wacker’s ketene process will not be able to compete with Lyondell on cost. The only other large producer is Lachema AS of the Czech Republic. TBAc’s main application is as a building block for pharmaceutical compounds and as an organic synthesis reagent.It can also be used as an environmentally friendly process solvent, an application that could potentially account for large volumes and which is being targeted by Lyondell. Current world demand is about 1 M lbs/year. …benzyl alcohol A new method for the production of benzyl alcohol has been described. The compound which is used as a solvent in the production of dyes, fragrances, paper chemicals and pharmaceuticals is conventionally made by the hydrolysis of benzyl chloride although yields are low and the levels of by-products are high.The new method gives up to 76% product with less than 2% by-product (Xiandai Huagong, 20 May 1999, 19, 26). …dimethyl carbonate A new process for the catalytic manufacture of dimethyl carbonate has been described.The reaction of carbon monoxide and oxygen in methanol can be efficiently catalysed with cobalt pyridine-2-carboxylate at a pressure of 2 MPa. This achieves a selectivity of 99% and a methanol conversion of 10.3%. The corrosion rate is believed to be less than the existing process based on copper(I) chloride catalysis. …methanol A new process for the production of methanol has been developed by Starchem Technologies.The new process can lead to a reduction in process costs of $50/tonne and a 25–40% reduction in capital costs. The new process is to be commercialised by Foster Wheeler under an agreement with Starchem. Greening aircraft deicing New jet fuel deicers which are less damaging to the environment and less harmful to humans have recently been patented by the US Navy.The compounds are acetal and ketal derivatives of glycerol. These are sufficiently soluble in jet fuels and are as effective as the current ethylene glycol-based deicers over a wide range of temperatures. At the concentrations needed to be effective for wing deicing, the current formulations are toxic and workers exposed to them have reported various health problems.Additionally the compounds can deplete rivers and streams of oxygen which can result in the death of aquatic life. (Chemistry in Britain, 17 October 1999). Environmentally friendly surfactants …The demand for non-ionic surfactants is growing and a new example of this is alkyl glycoside which is made from saccharide. This product can be used as a replacement for alkyaryl sulfonate anionic surfactants in shampoos. …Sodium silicate can be used as a more environmentally benign replacement for phosphorus containing additives in washing powders.In China, the use of phosphorus containing washing powders was banned in 1998 and the demand for sodium silicates has grown to 500,000 tonnes/year. …Three coconut oil soap bases for liquid cleansing applications have been developed by Concord-Chemical Company. One of these products has very light colour and low odour making it suitable for introducing dyes and fragrances.Useful chemicals from wastes MARS Technologies in Arizona have developed a new technology in mixed metals recovery from spent acid wastes which is an environmentally friendly alternative to deep-well disposal.Metal chlorides are absorbed by a standard ion-exchange resin, then selectively stripped by a patented method. The process has been used to recover zinc and ferrous chloride from 140 tones/month of pickle liquor in Baton Rouge, Louisiana. Zinc and a small amount of ferric salts are absorbed, then recovered. Ferrous chloride passes straight through the column and is stored for processing.In tests, the company has successfully recovered tin, copper, iron, antimony, nickel and chromium (further information is available from Robert Bradley: bradley@marstech.com; fax +1 520 514 5161; tel +1 520 514 5160). High-value products from scrap tyres The disposal of scrap tyres is a growing problem throughout the world. For example, in the European Union total scrap tyres are of the order of 2 million tonnes per year.In North America the problem is equally severe with 2.5 million tonnes produced each year with an estimated stock pile of 3000 million tyres awaiting disposal. The European Union has recognised scrap tyres as a ‘priority waste stream’ requiring special treatment and disposal and has recommended that a target of 65% recovery of scrap tyres should be set by the member states.The treatment and disposal option for tyres most commonly used throughout the European Union is landfilling, however, proposed EC legislation in the form of the European Waste Landfill Directive has the specific proposal to prohibit the landfilling of whole or shredded tyres. In addition, as the costs of disposal inevitably increase illegal dumping is likely to increase.Open dumping represents a problem for local communities in G164 Green Chemistry December 1999 This journal is © The Royal Society of Chemistry 1999C G Green Chemistry February 1999 G165 This journal is © The Royal Society of Chemistry 1999 N E W S that they are an eyesore and may result in accidental fires with high pollution emissions.In addition, tyres can be a breeding ground for insects and a home for vermin. The current disposal methods of landfilling of tyres is clearly a waste of a valuable resource and with increasing emphasis on recycling there are attempts to move the treatment of this waste stream higher up the hierarchy of waste management. Consequently alternative treatment and disposal routes for tyres are urgently being sought. Dr Paul Williams, Reader in Environmental Engineering in the Department of Fuel and Energy at the University of Leeds, UK, has recently been awarded a £107,000 research grant from the EPSRC to undertake research into pyrolysis of scrap tyres to produce high value products.Pyrolysis is the degradation of the rubber of the tyre using heat in the absence of oxygen.The tyres rather than burn, breakdown to give an oil and gas leaving a residual solid carbon and the steel casing of the tyre. Pyrolysis of tyres therefore produces an oil, carbon and gas product, in addition to the steel cord, all of which have the potential to be recycled. The yield of oil can be up to 58 wt% of tyre and the oil has broad fuel properties similar to commercial grade light fuel oil/diesel fuel. For example, the energy value of the oil is 42 MJ kg-1 and sulfur content between 0.5 and 1.5 wt% depending on process conditions, and therefore the pyrolysis oils may be combusted directly or added to petroleum-derived fuels.The pyrolysis gases are composed of mainly hydrogen, methane and other hydrocarbons and have sufficient energy value that they can be used to provide the energy requirements of the pyrolysis process.The solid carbon residue left after pyrolysis has potential as a solid fuel or as a low-grade carbon black. The EPSRC research grant has involved the design, commissioning and operation of experimental equipment in the department of Fuel and Energy at the University which uses fluidised bed and fixed bed technology to process the scrap tyres at temperatures between 450 °C and 700 °C.The scrap tyres thermally breakdown at such temperatures to produce the oils and gases and leave behind the residual carbon. The oils are condensed using a novel selective temperature condensation system, developed as part of the research grant, which concentrates the higher value aromatic chemicals as a separate fraction.The tyre pyrolysis oil is very aromatic and contains certain chemicals in high concentration. One example is limonene, which has wide industrial application in the formulation of industrial solvents, resins and adhesives and as a feedstock for the production of fragrances and flavourings. Most importantly it is biodegradable and environmentally safe and can be used as a replacement for CFCs.Limonene concentrations in selectively condensed fractions have reached 14% by weight in the experiments at Leeds, a concentration which can be separated using conventional processing to produce a commercially viable product. Also found in the tyre oil are indene, styrene, xylene and naphthalene all with a wide variety of industrial applications. The research work at Leeds has produced an upgrading process for the tyre-derived carbon which produces activated carbons of similar quality to those obtainable commercially. For example, surface areas of over 600 m2/g have been obtained in the experiments at the University. The process involves removal of the ash from the carbon using a simple acid wash procedure followed by activation at high temperatures of about 900 °C in the presence of steam or carbon dioxide. A wide variety of process parameters has been investigated to optimise the process, including activation temperature, particle grain size, the ratio of steam/carbon dioxide activation gas, activation time etc. The work at Leeds has also shown that the activated carbons have a porosity and sulfur content which is particularly suitable for the removal of cadmium and mercury from industrial aqueous waste-waters and flue gases. This pyrolysis process has the potential to recycle tyres to produce high value products which make recycling not only environmentally attractive, but also commercially attractive. A different approach — from Goodyear In a different approach to the scrap tyre disposal problem, Goodyear, the world’s largest tyre manufacturer, has patented a process that can efficiently devulcanise the rubber in old tyres—at least on a laboratory scale (US Patent 5 891 926). Researchers Larry Hunt and Ron Kovolac, working at Goodyear’s headquarters in Akron, Ohio, USA, found that supercritical 2-butanol (150–300 °C, 1000–1500 psi) exhibited the right solvation properties to extract natural rubber from the vulcanised product. The process breaks the carbon–sulfur and sulfur–sulfur crosslinks formed during the vulcanisation process, separating the rubber molecules from the oil, carbon black and sulfur present in the tyre compound. The extracted rubber is almost identical to virgin rubber, and can therefore be cured and used to make new products, but it remains to be seen if the process can be scaled-up successfully to provide a viable alternative to landfill disposal. Paul Williams from the University of Leeds whose new process for tyre pyrolysis could yield high-value chemicals. Photo: Richard Moran

ISSN:1463-9262    

DOI:10.1039/a909910g

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

Green Chemistry December 1999 G167 This journal is © The Royal Society of Chemistry 1999 F EAT U R E oncern over volatile organic solvent emissions and the generation of aqueous waste streams has prompted a number of chemists and chemical engineers to seek new, cleaner methods for polymer synthesis1 and polymer processing.2 The use of supercritical carbon dioxide (scCO2) has attracted particular attention in both of these areas for the following reasons: l CO2 is non-toxic, non-flammable, chemically inert, and inexpensive l Supercritical conditions are easily obtained: Tc (CO2) = 31.1°C; Pc, (CO2) = 73.8 bar (Figure 1) l The solvent may be removed by simple depressurisation l The density of the solvent can be ‘tuned’ by varying the pressure l Many polymers become highly swollen and plasticised in the presence of CO2 On the other hand, the use of supercritical fluids requires elevated pressures and relatively specialised equipment, and these considerations must be balanced carefully with the perceived advantages for a given application.However, there are many recent examples which suggest that the benefits of using CO2 as an alternative solvent might warrant the C G additional complexity associated with supercritical fluid technology, at least for certain applications.The aim of this article is to highlight some of these areas.3 Polymer synthesis Much of the pioneering work in the field of polymer synthesis using scCO2 has been carried out by Professor J. M. DeSimone and colleagues at the University of North Carolina at Chapel Hill (UNC), USA.4 In 1992, this group showed that it was possible to synthesise amorphous fluoropolymers in CO2 under relatively mild conditions by homogeneous solution polymerisation.5 Since the only other solvents for these polymers tend to be chlorofluorocarbons (CFCs), the use of CO2 represents a much cleaner route to materials of this type.However, with the exception of certain amorphous fluoropolymers and polysiloxanes, the vast majority of polymers show negligible solubility in CO2 under practicable conditions (<100 °C, <100 bar). Hence, a number of research groups have studied the synthesis of polymers by heterogeneous polymerisation in scCO2 (i.e., under conditions where the resulting polymer is not soluble in the supercritical solvent).In 1994, DeSimone demonstrated that it was possible to synthesise polymers such as poly(methyl methacrylate) (PMMA) in CO2 by dispersion polymerisation using specially designed, CO2-soluble surfactants.6 Since dispersion polymerisation is usually carried out in solvents such as hydrocarbons or C1–C5 alcohols, the use of CO2 has potential to reduce organic solvent usage.These techniques have recently been extended to the synthesis of a range of materials, including waterdispersible polymer powders7 and well-defined cross-linked microspheres (Figure 2).8 Water-dispersible powders are useful because they can be transported dry, thus saving on transport costs, while cross-linked microspheres are very important in applications such as chromatographic separations and polymer-supported synthesis. The use of scCO2 for the synthesis of porous polymers is an area of great interest, particularly since conventional processes tend to be solvent intensive and can generate materials containing organic solvent residues which may be difficult to remove.Carbon dioxide has allowed the ‘solvent-free’ preparation of polymeric materials with pore sizes spanning a very broad range, from microcellular foams down to macroporous resins (Figure 3) and mesoporous/microporous aerogels.9 In the UK, several academics are investigating aspects of the use of CO2 for polymer synthesis, including groups in Nottingham, Cambridge, and Liverpool.10 Polymer processing Carbon dioxide has been used in a wide range of polymer processing applications, the most established of which are polymer fractionation and extraction.11 Both of these techniques exploit the variable density which is associated with supercritical fluid solvents.More recently, there has been much interest n the use of CO2 for the infusion or ‘impregnation’ of molecules into Clean polymer synthesis and processing using scCO2 Andrew Cooper from Liverpool University in the UK describes how scCO2 (supercritical carbon dioxide) is proving to be a valuable green alternative to conventional solvents in polymer synthesis and processing C Figure 1 Schematic phase diagram for CO2 showing the supercritical region Figure 2 Cross-linked polymer microspheres synthesised in scCO2, average diameter = 410 nm, see ref. 8F EAT U R E C G G168 Green Chemistry December 1999 This journal is © The Royal Society of Chemistry 1999 polymeric materials.From an environmental perspective, a particularly exciting technique is disperse dyeing using scCO2.12 In this approach, the dye molecule has very low solubility in CO2 (e.g., mole fractions of 10-5–10-6) However, because the dye molecules partition preferentially into the polymer phase, significant quantities of dye can be loaded into the polymer in a relatively short period.13 In addition to using a clean solvent, very little dye is actually dissolved in the fluid at any given time, thus minimising dye loss and environmental burdens.Another exciting processing technique is the Vedoc Advanced Materials Process or ‘VAMP®’, which was recently commercialised by Ferro Corporation (Cleveland, OH).14 This process utilises the fact that CO2 is a good plasticising agent (i.e., it can cause polymers to soften and flow, even at low temperatures).The method has been applied successfully to low-temperature processing of a range of composite materials, particularly polymer–pigment formulations for use as powder coatings. Other important methods for polymer particle formation include rapid expansion from supercritical solutions (RESS) and a range of antisolvent precipitation techniques.15 Supercritical CO2 has also been exploited for the solvent-free application of protective fluorinated coatings16 and for dry-cleaning,17 the latter of which has already shown real commercial promise.Finally, carbon dioxide has been viewed as a potential solvent for microlithography.At present, the semiconductor industry produces millions of gallons of organic and aqueous waste effluent every year, all of which requires treatment. Supercritical solvents offer the possibility of simpler separations and recycling, and new processes are under evaluation which use CO2 as the solvent, both in the spin-coating stage and also in the development step.18 Conclusions Carbon dioxide has great potential as an alternative solvent for polymer synthesis and processing.The drive to use CO2 is especially strong in the case of processes which use volatile organic solvents. However, there may also be cases where CO2 is a viable substitute in aqueous processes, particularly if separations are simplified by the use of a supercritical solvent.A major breakthrough in the acceptance of this technology would be the generation of novel polymeric materials that are difficult or even impossible to obtain without the use of supercritical fluids. Whilst this may be a challenging goal, the rapid growth of this area over the last few years suggests that we will see future developments in the use of CO2 for the synthesis and processing of progressively more advanced materials.References 1 J. L. Kendall, D. A. Canelas, J. L. Young and J. M. DeSimone, Chem. Rev., 1999, 99, 543. 2 (a) B. Bungert, G. Sadowski and W. Arlt, Ind. Eng. Chem. Res., 1998, 37, 3208; (b) C. A. Eckert, B. L. Knutson and P. G. Debenedetti, Nature, 1996, 383, 313. 3 This short article is based on a fulllength review which will appear in the Journal of Materials Chemistry: A.I. Cooper, J. Mater. Chem., 2000, 10, in press. 4 http://www.unc.edu/depts/chemistry/ faculty/jmd/jmdhmpg.html 5 J. M. DeSimone, Z. Guan and C. S. Elsbernd, Science, 1992, 257, 945. 6 J. M. DeSimone, E. E. Maury, Y. Z. Menceloglu, J. B. McClain, T. J. Romack and J. R. Combes, Science, 1994, 265, 356. 7 M. Z. Yates, G. Li, J. J. Shim, S. Maniar, K. P. Johnston, K. T. Lim and S. Webber, Macromolecules, 1999, 32, 1108. 8 A. I. Cooper, W. P. Hems and A. B. Holmes, Macromolecules, 1999, 32, 2156. 9 (a) K. L. Parks and E. J. Beckman, Polym. Eng. Sci., 1996, 36, 2417; (b) A. I. Cooper and A. B. Holmes, Adv. Mater., 1999, 11, 2170; (c) D. A. Loy, E. M. Russick, S. A. Yamanaka, B. M. Baugher and K.J. Shea, Chem. Mater., 1997, 9, 2264. 10 http://www.nottingham.ac.uk/ ~pczsp/clnthome.html http://www.ch.cam.ac.uk/ CUCL/MLPS/ http://www.liv.ac.uk/Chemistry/Staff/ coopera.html 11 M. A. McHugh and V. J. Krukonis, Supercritical Fluid Extraction, 2nd ed., Butterworth-Heinemann, Stoneham, MA, 1994. 12 S. G. Kazarian, N. H. Brantley and C. A. Eckert, Chemtech, 1999, 29, 36. 13 B. L. West, S. G. Kazarian, M. F. Vincent, N. H. Brantley and C. A. Eckert, J. Appl. Polym. Sci., 1998, 69, 911. 14 F. S. Mandel, Proc. 5th ISASF Meeting on Supercritical Fluids, Chemistry and Materials: Nice, France, 1998, T1, pp 69. 15 (a) P. G. Debenedetti, J. W. Tom, X. Kwauk and S.-D. Yeo, Fluid Phase Equilib., 1993, 82, 311; (b) E. Reverchon, J. Supercrit. Fluids, 1999, 15, 1. 16 F. E. Henon, M. Camaiti, A. L. C. Burke, R. G. Carbonell, J. M. DeSimone and F. Piacenti, J. Supercrit. Fluids, 1999, 15, 173. 17 http://www.micell.com 18 (a) C. K. Ober, A. H. Gabor, P. GallagherWetmore and R. D. Allen, Adv. Mater., 1997, 9, 1039; (b) J. M. DeSimone, Proc. Polymer ’98 Meeting, Brighton, UK, 9-11 September 1998, pp. 5. Figure 3 Internal structure of a porous polymer monolith synthesised using scCO2, average pore size = 7.8 mm, see ref. 9(b) Biography Andrew Cooper obtained his PhD at the University of Nottingham, working with Professor Martyn Poliakoff in the area of organometallic chemistry. He then spent two years (1995–1997) as an 1851 Research Fellow at the University of North Carolina at Chapel Hill, USA, working with Professor Joseph DeSimone on the development of novel dendritic surfactants for extractions using CO2 as the solvent (Cooper et al., Nature, 1997, 389, 368). From 1997 to 1999, he held a Ramsay Memorial Research Fellowship at the Melville Laboratory for Polymer Synthesis in Cambridge, UK, working with Professor Andrew Holmes on polymer synthesis using supercritical CO2 (Cooper et al., Macromolecules, 1999, 32, 2156). He was appointed as a Royal Society University Research Fellow at the University of Liverpool, UK, in January 1999.

ISSN:1463-9262    

DOI:10.1039/a909911e

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

Green Chemistry December 1999 G169 This journal is © The Royal Society of Chemistry 1999 Which magazine has published its findings from a review of eco-labelling schemes for domestic products. In 1998 the UK Government launched a voluntary code of practice—the Green Claims Code—to give guidance to manufacturers wishing to make green claims about their products. It was hoped that the code would help to avoid confusing logos and misleading statements and claims and enable consumers to better judge the relative environmental merits of different products. The verdicts on some of the schemes are summarised below. The Forest Stewardship Council (FSC) This was set up in 1993 and is meant to show which wood-based products come from well-managed forests and cause minimal environmental and local community damage.Which found this to be an example of a good environmental- labelling scheme with clear objectives focused targets and thorough monitoring. Volatile organic compounds (VOCs). This was developed by the B&Q stores and was meant to inform customers of the level of VOCs in paints and varnishes. Not all manufacturers have adopted the scheme. Which view this as an important scheme and suggest that it can be improved through independent tests and more consistent reporting of information by the various manufacturers. Washright. This was launched in 1998 and is part of a campaign by the European soap and detergent manufacturer’s trade association to reduce the environmental impact of laundry detergents by 2002. This scheme is meant to educate users about the correct quantity of detergent that should be used and to reduce the energy consumed per application.All UK laundry-detergent manufacturers are taking part in this voluntary scheme. Which found that not all manufacturers gave clear information and some simply refer the customer to a web site. Which also reported on the failure of the eco-labelling scheme. This was launched by the EU in 1992 with the aim to endorse products that cause less damage to the environment during their use or production. Unfortunately take-up of the scheme has been very slow with only about 200 products having been awarded. This lack of popularity is at least partly due to the high fees as well as to competition with local environmental schemes. The scheme is currently being revised. Which also revealed some remaining examples of unhelpful and misleading green logos and statements on packaging.These include l claims on aerosol products to be ‘CFCfree’ even though CFCs have not been used in consumer aerosols for 10 years l claims on washing powders that they contain biodegradable detergents when all such materials must be biodegradable by law l claims on paint products that they have ‘no added lead’ when its been illegal to add lead to paint for 10 years Which October 1999 DOE support for alternative fuels The US Department of Energy (DOE) has awarded a $4.2M grant towards a $5.4M research project on the production of cleaner alternative fuels and premiumquality chemicals. This project is backed the Consortium for Fossil Fuel Liquefaction Science (CFFLS)— a five- University partnership (University of Kentucky University of Pittsburgh University of Utah West Virginia University Auburn University) engaged in a broad research program to liquefy waste material with coal to transform a major environmental disposal problem into a valuable transportation fuel C G FOR U M resource.Specific projects under the DOE grant will include new methods of using coal coke municipal waste and natural gas along with unconventional chemical processes (Oil and Gas 1999 97 4). For more information on the CFFLS see http://www.uky.edu/CFFLS/ Tougher pollution legislation The EPA in Washington is to introduce tougher new legislation on emissions form trucks. Details are to be expected within weeks. Environmentalists have claimed that 26% of the smog-causing nitrogen oxides are emitted from larger trucks even though they only represent 2.5% of all vehicles on the US roads.Earlier this year the EPA proposed to sharply cut smog-causing chemicals found in automobiles as well as new requirements for low-sulfur gasoline across the USA. The tougher emissions and fuel standards for large trucks will begin to be phased in by 2007 (Reuters News Service). Germany pushes for sulfur-free diesel Germany has urged the EU to introduce sulfur-free diesel by 2007. They believe that the 1998 agreement to reduce the sulfur levels to 50 ppm did not go far enough. It called for fuels with less than 10 ppm sulfur to be available from 2005 and mandatory by 2007. Reduced sulfur levels will have multiple benefits including increased lifetimes for catalytic converters reduced fuel consumption and reduced emissions.Germany will offer tax incentives for sulfur-free fuels from January 2003 (Reuters News Service). Greening the HSE One of the major considerations of the Environmental Audit being carried out by the Health and Safety Executive (HSE) has been the UK Government’s initiative to green its departments. Following this the ‘Green Team’ was launched in July 1999 with responsibilities to create and monitor a programme for improving the environmental impact of HSE’s operations and leading all relevant HSE Eco-labelling for domestic products initiatives. Initially they are expected to produce a Green Improvement Programme which will include conserving resources such as water energy etc and minimising waste. The HSE also wants a network of green contacts to be established throughout the HSE (http://www.open.gov.uk/hse/ hsehome.htm).Green Chemistry Network concentrates on education In recent months the Green Chemistry Network (GCN) has started to concentrate more effort to get green chemistry concepts into schools. We have been working with the editorial board of Chemistry Review (Philip Allan Publishers ISSN 0959 8464) to provide a variety or articles covering many aspects of green chemistry. Green chemistry will be the theme running throughout volume 9 of the journal; issues 1 and 2 gives an overview of the subject together with more detailed articles on how catalysis can improve atom economy the search for ecofriendly electroplating electrolytes and green chemistry resources available on the web. We are also becoming increasingly involved in RSC’s Chemistry at Work events about 70 GCSE pupils from six schools in North Yorkshire attended a recent event at York.The level of understanding they demonstrated about green issues was high and they were particularly interested in what industry is doing to become greener. We are also involved in running a schools challenge (along with ACTIN) on the uses of renewable resources as chemical feedstocks. This is part of a wider Food and Farming Challenge run by the Yorkshire Agricultural Society as an annual event and involves 14–18 year olds researching and presenting a report on a scientific issue connected with agriculture. The RSC’s Environmental Chemistry Group the RSC’s Education Division and the GCN are planning a one-day conference/ training course for teachers and lecturers on green chemistry and environmental sciences relevant to the curriculum.This event will be held in London on 25 March 2000. Joe Breen Memorial Scholarship Letter from Dennis Hjeresen Acting Director of the Green Chemistry Institute Following the sad passing of Joe Breen one of the fathers of green chemistry this past summer a Joe Breen Memorial Scholarship was established. The current fund stands at about $2200 and the American Chemical Society has generously offered to match the fund if it exceeds $2500. Thus I am requesting additional donations to enable the matching sum to be exceeded. Information will be released shortly on how to apply for scholarship funding and the necessary criteria but it is intended that the funds will be directed to an educational activity—very much in the spirit of Joe Breen. Donations should be sent to The Green Chemistry Institute Internship Program The Green Chemistry Institute 600 Barranca Road Los Alamos NM 87544 USA Thanks Dennis L. Hjeresen Los Alamos National Laboratory e-mail dennish@lanl.gov F O R UM C G G170 Green Chemistry December 1999 This journal is © The Royal Society of Chemistry 1999 Know of any green chemistry activities? If you have any items relating to green chemistry initiatives funding opportunities or regulatory activities which could be included in the FORUM section of Green Chemistry please send them to James Clark or Duncan Macquarrie [email greenchem@york.ac.uk; FAX +44 (0)1904 434533 or +44 (0)1904 423559]

ISSN:1463-9262    

DOI:10.1039/a909912G

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

Green Chemistry December 1999 G171 This journal is © The Royal Society of Chemistry 1999 Because of this, crossflow microfiltration is particularly useful for continuous processes. Microfiltration is the oldest of the membrane separation technologies but its industrial implementation has been much slower than expected; to a considerable extent this is due to the initial rapid decline in permeate flux.Wakeman has spent much time looking at the cause and potential solutions to this problem, some of the conclusions are shown in Table 1. Potential industrial applications One method for reducing cake formation and fouling and hence increasing the flux rate is to apply an additional force field such as direct current or acoustic fields to the membrane. The effect of the electric field is to alter the direction of the particle such that it does not approach the membrane surface.Wakeman has used this technique in the development of technology for the microfiltration (through tubular ceramic membranes) of titanium dioxide dispersions, a frequent problem for the paint and coatings industries. For F O C U S O N . . . Separation processes at Loughborough University example dilute dispersions of titanium dioxide in sulfuric acid may readily be concentrated from 2% to 60%.Wakeman’s long-term aim is to develop a process using a.c. as this will be much safer to use on an industrial scale than the present d.c. technology. A problem often encountered by biotechnology companies concerns concentration of solutions containing small amounts of protein, Wakeman has demonstrated that electrically enhanced microfiltration technology is highly suited to this application, however there is a limit to the electrical potential that can be used due to localised heating which may cause degradation of the protein structure.However the technology has advantages over centrifuges which are commonly used for this process since the high shear associated with centrifuges also lead to protein degradation.Electrical enhancement of membrane filtration processes is highly efficient leading to smaller more versatile filtration equipment. C G Mike Lancaster looks at the separation process research being carried out at Loughborough, UK, with emphasis on the membrane work of Professor Richard Wakeman and colleagues ost chemists, by training, focus on the chemical reaction, maximising yield and raw material utilisation. Green chemistry however needs to take account of post reaction processes such as product isolation, purification and recycling of non-product streams.In these areas the scope for the traditional chemist to make an impact is often limited and it is left to the chemical engineer to drive towards cleaner technology. The Chemical Engineering Department at Loughborough University is particularly strong in the area of separation processes, both physical (e.g.gas or liquid filtration and membrane processes) and chemical (e.g. using ion exchange resins to remove toxic metals). Professor R. J. Wakeman obtained his B.Sc. and Ph.D. from UMIST and spent a short period in industry with Lennig Chemicals before embarking on his academic career.Before taking up his current position at Loughborough in 1995 he spent time at UMIST and Exeter. He is currently chair of the European Federation of Chemical Engineers working party on Filtration and Separation. Crossflow membrane microfiltration is currently one of Richard Wakeman’s main areas of interest.This separation process is particularly useful for removal of dispersed materials in the size range 0.05 to 10 microns from a liquid steam by forcing the liquid through a porous membrane. In crossflow filtration the dispersion flows tangentially to the membrane surface, this flow generates forces which tend to remove the deposited layers from the membrane surface thus helping to keep the membrane clean and lengthening the time between cleaning procedures and membrane replacement.M Table 1 Some parameters effecting flux decline in crossflow microfiltration Parameter Effect Crossflow velocity Increase in crossflow velocity increase flux for systems containing high amounts of particle fines Filtration pressure High pressures lead to higher fluxes for systems containing large particles (over 24 micron) Membrane wettability Hydrophobic membranes have higher initial fluxes than hydrophilic one - but they even out with time Membrane morphology This has an effect when a small fraction of fines are present in a low concentration suspension Professor Richard WakemanG172 Green Chemistry December 1999 This journal is © The Royal Society of Chemistry 1999 Use of acoustics to prevent fouling is useful for dispersions containing fine particles suspended at around 1000 ppm where normal filtration rates are low.Ultrasound behaves in a similar way to electric fields, changing the particles trajectory. Using this technique it is possible to increase the concentration of particles by 50% per pass. This is of current interest to water companies for removal of hydrocarbon pollutants, although the volumes involved are too great for ultrasound to be used commercially at present.Professor Wakeman has used his membrane expertise to assess methods of removing pollutants from both wastewater and in process effluent streams, with the duel aim of producing clean water and recovering the pollutants for reuse.One particular area he has studied is removal of latex particles, widely used in paints and adhesive formulations and frequently found at the 1% level in discharges from manufacturing processes. To make re-use economical these particles need to be concentrated up to around 30%. This has been shown to be viable by use of flocculants such as acrylic acid / fatty ester copolymers to prevent the latex particles blocking the membrane pores.Other applications Wakeman’s group have worked on include the pilot scale separation of different types of surfactant from process waste streams. If small units are fitted to the end of each manufacturing plant this technology has potential for significantly reducing the amount of surfactant waste leaving the factory.Separation of oil-in-water emulsions Dr Iain Cumming along with Dr Richard Holdich have been applying novel membrane technology to a problem common to many industries that of breaking oil-in-water emulsions. Oil-in-water emulsions are produced in large volumes during offshore oil production, from metal working and during food manufacture, although membranes have been used for breaking these emulsions the process has never been very efficient.The Loughborough team discovered that this was largely due to the way membranes are manufactured. Normal membranes do not have straight through pores instead the channels are interwoven and the separation is via depth filtration. Excellent results have been obtained by using straight through metallic tubular crossflow membrane filters, giving oil rejections up to 97%.Cumming, in co-operation with Dr Klaus Hellgardt is about to begin work on a new research topic, which could provide a safe, simple and clean alternative to many oxidation processes. They are working on membranes whose oxygen permeability is controlled by an electric current. A tubular membrane reactor is envisaged in which the inner membrane surface is coated with catalyst, hydro-carbons are pumped into the tube and oxygen (from air) enters through the membrane in a controlled manner by manipulation of the electric current.Hence the oxidation process can be easily carried out outside the flammability limits using air as the oxidant source. There is some precedent for such membranes, in the US Air Products have started to use similar membranes for separating oxygen from air in place of cryogenics.Chemical separation processes As well as all the research into physical separation processes there is a significant amount of work being carried out at Loughborough on chemical separations including adsorption of trace toxic metals and organic pollutants from aqueous streams using, for example, ion exchange resins and hypercrosslinked polymers.Leading this work is Head of Department Professor Michael Streat. Streat has been working with the metal plating industry for some time to identify simple, inexpensive solutions to help the many small companies involved clean up their effluent. Much of this work has centred on the use of novel chelating ion exchange resins containing aminophosphonate or amidoxime type groups to remove pollutants such as Cu, Ni, Zn, Co, Cr and Cd ions from plating effluent streams.More recently the group has demonstrated the benefits of using seaweed for this purpose. This work, carried out under the EU Brite-Euram project and trialed in Finland has shown that it is the carboxylate groups present on the seaweed which are vital for activity.In many cases treated seaweed has outperformed commercial ion exchange resins. Further work by Streat’s group at reducing the cost of separation processes, making them more accessible to smaller companies is aimed at producing activated carbon from renewable waste sources. Potential sources of this carbon include waste sugar beat and straw. The main focus of the work is centred on optimising the carbonisation process to produce carbon with the correct physical form, porosity and surface area. It is expected that carbon suitable for both removal of toxic metals and trace organic pollutants such as pesticide residues will be produced.F O C U S O N . . . C G Reactive distillation One of Professor Streat’s leading coworkers over recent years is Dr Basu Saha who has recently been appointed to a lectureship at Loughborough.Dr Saha is currently establishing his own ‘Green Chemistry’ research programmes in the area of reactive distillation. Reactive distillation has received considerable attention in recent years as an advance over conventional processes where the conversion is limited by unfavourable chemical equilibrium.The main advantages of this process, relative to conventional alternatives are the possibility of carrying out equilibrium limited reactions to completion and simultaneous removal of the product from the reaction mixture in a single unit, which in turn reduces reactor and recycle cost. Ion exchange resins also find application in reactive distillation columns where they play the dual role of catalyst as well as tower packings.In recent years, reactive distillation has been considered for the important anti-knock compound MTBE and for the manufacture of high purity methyl acetate. The conversion of formic acid, in aqueous solutions, to cyclohexyl formate by reaction with cyclohexene, in a reactive distillation column packed with an acidic ion exchange resin catalyst has been studied by Saha. A favourable comparison between the rate of esterification in batch mode and in a reactive distillation column was made. Other processes Dr Saha will be studying include recovery of dilute acetic acid solution by esterification with alcohols and various transesterification processes. Further reading 1. For more information on crossflow microfiltration see R H Davis in Membrane Handbook, published by Van Nostrand Reinhold, 1992 pp. 480-505 2. E. S. Tarleton and R.J. Wakeman, Trans. IChemE, 1994, 72(A), 521 3. R. J. Wakeman and M. N. Sabri, Trans. IChemE, 1995, 73(A), 455 4. R. J. Wakeman, Trans. IChemE, 1998, 76(C), 53 5. R. G. Holdich, I. W. Cumming and I. D. Smith, J. Membrane Sci. 1998, 143, 263 6. D. J. Malik, M. Streat and J. Greig, Trans. IChemE, 1999, 77(B), 1 7. B. Saha and M. M. Sharma, React. Funct. Polym., 1996, 28, 263

ISSN:1463-9262    

DOI:10.1039/a909913a

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

oxidation technique for treating wood pulp, which translates to energy savings for the industry. Environmental compliance costs may be expected to decrease with this new approach because chlorinated organics are not generated in this totally chlorine free process. TAML™ activators may also be applied to the laundry field, where most bleaches are based on peroxide. When bound to fabric, most commercial dyes are unaffected by the TAML™-activated peroxide.However, random dye molecules that ‘escape’ the fabric during laundering are intercepted and destroyed by the activated peroxide before they have To Terrence J. Collins, Carnegie Mellon University for the development TAML™ Oxidant Activators used in general activation of hydrogen peroxide for green oxidation technologies. In nature, selectivity is achieved through complex mechanisms using a limited set of elements available in the environment.In the laboratory, chemists prefer a simpler design that utilizes the full range of the periodic table. The problem of persistent pollutants in the environment can be minimized by employing reagents and processes that mimic those found in nature. By developing a series of activators effective with the natural oxidant hydrogen peroxide, Professor Terry Collins has devised an environmentally-benign oxidation technique with widespread applications.TAML™ activators (tetraamido-macrocyclic ligand activators) are iron-based and contain no toxic functional groups. These activators offer significant technology breakthroughs in the pulp and paper industry and the laundry field.The key to quality papermaking is the selective removal of lignin from the white fibrous polysaccharides, cellulose, and hemicellulose. Wood-pulp delignification has traditionally relied on chlorine-based processes that produce chlorinated pollutants. Collins has demonstrated that TAML™ activators effectively catalyze hydrogen peroxide in the selective delignification of wood pulp.This is the first low-temperature peroxide a chance to transfer to other articles of clothing. This technology prevents dye-transfer accidents while offering improved stain-removal capabilities. Washing machines that require less water will be practical when the possibility of dye-transfer is eliminated. An active area of investigation is the use of TAML™ peroxide activators for water disinfection.Ideally, the activators would first kill pathogens in the water sample, then destroy themselves in the presence of a small excess of peroxide. This protocol could have global applications, from developing nations to individual households. More 1999 Presidential Green Chemistry Awards Paul Anastas, Mary Kirchchoff and Tracy Williamson of the US EPA present the last in a series of short profiles on this year’s Presidential Green Chemistry Awards. 19 9 9 G R E E N C H E M I S T R Y AWA R D S C G G174 Green Chemistry December 1999 This journal is © The Royal Society of Chemistry Green Chemistry Challenge Award presented to Terrence J CollinsGreen Chemistry December 1999 G175 This journal is © The Royal Society of Chemistry 1999 19 9 9 G R E E N C H EMI S T R Y AWA R D S C G The versatility of the TAML™ activators in catalyzing peroxide has been demonstrated in the pulp and paper and laundry industries.Environmental benefits include decreased energy requirements, elimination of chlorinated organics from the waste stream, and decreased water usage. The development of new activators and new technologies will provide environmental advantages in future applications.To Lilly Research Laboratories for their practical application of a biocatalyst in pharmaceutical manufacturing The synthesis of a pharmaceutical agent is frequently accompanied by the generation of a large amount of waste. This should not be surprising, as numerous steps are commonly necessary, each of which may require feedstocks, reagents, solvents, and separation agents.Lilly Research Laboratories has redesigned its synthesis of an anticonvulsant drug candidate, LY300164. This pharmaceutical agent is being developed for the treatment of epilepsy and neurodegenerative disorders. The synthesis used to support clinical development of the drug candidate proved to be an economically viable process, although several steps proved problematic.A large amount of chromium waste was generated, an additional activation step was required, and the overall process required a large volume of solvent. Significant environmental improvements were realized upon implementing the new synthetic strategy. Roughly 34,000 liters of solvent and 300 kg of chromium waste were eliminated for every 100 kg of LY300164 produced.Only three of the six intermediates generated were isolated, limiting worker exposure and decreasing processing costs. The synthetic scheme proved more efficient as well, with percent yield climbing from 16% to 55%. The new synthesis begins with the biocatalytic reduction of a ketone to an optically pure alcohol. The yeast Zygosaccharomyces rouxii demonstrated good reductase activity, but was sensitive to high product concentrations.To circumvent this problem, a novel three-phase reaction design was employed. The starting ketone was charged to an aqueous slurry containing a polymeric resin, buffer, and glucose, with most of the ketone adsorbed on the surface of the resin. The yeast reacted with the equilibrium concentration of ketone remaining in the aqueous phase.The resulting product was adsorbed onto the surface of the resin, simplifying product recovery. All of the organic reaction components were removed from the aqueous waste stream, permitting the use of conventional wastewater treatments. A second key step in the synthesis was selective oxidation to eliminate the unproductive redox cycle present in the original route.The reaction was carried out using dimethylsulfoxide, sodium hydroxide, and compressed air, eliminating the use of chromium oxide, a possible carcinogen, and preventing the generation of chromium waste. The new protocol was developed by combining innovations from chemistry, microbiology, and engineering. Minimizing the number of changes to the oxidation state improved the efficiency of the process while reducing the amount of waste generated.The alternative synthesis presents a novel strategy for producing 5H-2,3-benzodiazepines. The approach is general and has been applied to the production of other anticonvulsant drug candidates. The technology is low cost and easily implemented and should have broad applications within the manufacturing sector.Chemistry Awards Following the success of these Presidential Green Chemistry Awards in the USA, awards for Green Chemistry have been established in the UK, supported by The Royal Society of Chemistry (RSC), Salters’ Company, the Jerwood Foundation, Department of Trade and Industry (DTI) and Department of the Environment, Transport and the Regions (DETR).The awards are designed to encourage more people to engage in Green Chemistry research, promote recent developments by industry and encourage sharing of best practice. Awards will be made both for academic research and commercial development by industry of Green Chemical Technology. Full details of the awards were published in the October issue of Green Chemistry and further information can be obtained from Mike Lancaster [email: greennet@york.ac.uk, Tel: (01904) 434549, Fax: (01904) 434550]. Administration will be carried out by the Green Chemistry Network at the University of York with an expert panel appointed by the RSC and Salters’ judging the nominations. The first of these annual awards will be made next year with nominations closing 31 March 2000.

ISSN:1463-9262    

DOI:10.1039/a909914j

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

F EAT U R E C G G176 Green Chemistry December 1999 This journal is © The Royal Society of Chemistry 1999 diagram. A lost work analysis reveals internal losses due to process imperfections, whereas an energy analysis has to ascribe losses to waste material and heat streams leaving the process (i.e., physical streams). The input-side of such a process is represented by natural resources (primary resources).No distinction has been made between resources used as feedstock and resources applied as fuel; they all are quantified by their theoretical workpotential, the universal measure. The output- side is represented by the theoretical work-potential of the desired product(s) and of recovered useful heat (in the form of a steam credit). By comparing the total amount of work-potential entering and leaving the process, the loss of work-potential is revealed, which is either due to processinefficiencies or material/heat release to the environment, so internal and external losses are lumped.All data have been taken from published literature (Table 1). ntroduction The process industry is a large consumer of raw materials, which are utilised both as feedstock for its numerous products and as energy source to drive its numerous processes. In the scope of sustainable development, consensus on the limited availability of our natural resources, and on the need for closed cycles in our ecosphere has grown.Hence, the current approach of our process industry is in question. One might raise the question ‘how sustainable are we?’ In answering this question, first, we have to fall back to the efficiency question.There is a need for quantitative figures on the efficiency with which natural resources are consumed. Such quantitative figures can be provided by the known thermodynamic concept of lost work, indicating the discrepancy between the ideal thermodynamic situation and our current process technology. This paper is partly based on the work presented by Hinderink et al.(1996a). Lost work in the process industry Lost work analysis has so far drawn the most attention in the energy-systems area, where heat is converted to power or electricity. It has less penetrated into the chemical process industry, perhaps because of its greater complexity. Work-potential of materials (chemical exergy) The theoretical work-potential of an energy-source depends on the extent to which it deviates from equilibrium with its natural surrounding.When heat and material streams are ideally brought in equilibrium with their surroundings, a maximum amount of work is available, which is often called ‘exergy’. If such an equilibration is not carried out ideally— which is always the case for real processes—a less than maximum amount of work is available, the remainder being lost, i.e.lost work. The precise calculation of the work-potential of material streams has been described by Szargut et al. (1988), and Hinderink et al. (1996b). Lost-work analysis (exergy analysis) In real material conversion processes, primary materials (natural resources) are converted to consumer materials and heat.These processes do not proceed ideally, so part of the work-potential of the primary materials will be lost. To obtain a ‘feeling’ for lost work in the process industry, the production processes of several ‘large-quantity’ products have been analysed. This paper only focuses on input and output streams of the conversion process; production of the natural resources, transportation, and storage, are excluded from the system boundary, because most often the largest part of lost work is occurred in the conversion step.Elaborate lost work analyses are given, for example, by Hinderink et al. (1996c) and Wall (1988). Figure 1 illustrates the general result of a lost-work analysis of a material conversion process in a so-called Grassmann On the efficiency and sustainability of the process industry I P.Hinderink of the Process Design Center in Breda, and H. J. van der Kooi and J. de Swaan Arons, both from the Laboratory of Applied Thermodynamics and Phase Equilibria at the Delft University of Technology (all in The Netherlands) explore the use of the thermodynamic concept of lost work for discussing the sustainability of the process industry.Figure 1 Generic Grassmann diagram for a material and energy conversion process.Green Chemistry December 1999 G177 This journal is © The Royal Society of Chemistry 1999 The processes Table 1 gives a ‘thermodynamic blueprint’ of some large-scale production processes. The numerical values presented refer to the technology level of the 1970s or 1980s and are based on primary (natural) resources only, e.g.natural gas and air. Because only primary resources are allowed to enter the processes, several sub-processes can be present inside the system, e.g. for the generation of intermediate products, or for the generation of steam or electricity. Lost work involved with the latter type of subprocesses is handled by using commonly applied second law-efficiencies (e.g. 50% for power production via cogeneration). An example of a process with an intermediate product is the urea process. The second step, starting from ammonia, is over 90% efficient, whereas the total process— thus having ammonia just as an intermediate product—shows an efficiency of only half of this value. For the nitric acid process, the second step is the least efficient as indicated by the simplified Grassmann diagram in Figure 2.C G F E AT U R E The left-hand box overleaf gives the calculation procedure for the theoretic workpotential of natural gas. The right-hand box overleaf presents the lost-work analysis for the production of hydrogen from natural gas via the steam reforming route. Figure 2 Simplified Grassmann diagram for the nitric acid process Results of lost-work analyses strongly depend on the system boundary considered and the credit that is given to co-products and by-products.Therefore, the analysis results can vary per author. Thermodynamic efficiency Although efficiency-values can be misleading because they can be defined in numerous ways (Wall, 1977; Gong and Wall, 1997), they are easy to handle.The definition of thermodynamic efficiency applied here is the ratio between workpotential of the desired products (excluding useful heat) and the primary resources applied. Usually, thermodynamic efficiencies based on lost-work analysis do not exceed 70% when starting from primary resources. At the higher side of the efficiency- range, the production of organic products can be found, while inorganic and metallurgical processes are at the lower side of the efficiency range.A combination of low efficiency and high input of work-potential indicates the need for process improvement. An overview of absolute lost work figures for the process industry, e.g. as shown in Figure 3, is more distinct and can be of use to determine which products and/or which processes need to be reconsidered in view of sustainable development.Table 1 Results of global lost work analyses of several important production processes Thoretical work-potential [kJ/mol final product] Final Molecular Raw Data taken Technology Raw Final Steam Lost thermodynamic product weight materials from level materials product credit work efficiency * [%] hydrogen 2 natural gas/air Giacobbe et al. 1990 409 236 28 145 58 ammonia 17 natural gas/air Cremer 1980 763 338 85 340 44 aluminum 27 bauxite Szargut; Habersatter 1990 4703 888 n.a. 3815 19 methanol 32 natural gas/air Supp 1985 1136 717 80 339 63 oxygen 32 air Ullmann 1980 64 4 n.a. 60 6 urea 60 natural gas/air Cremer; Pagani 1980 1590 686 150 754 43 via ammonia nitric acid 63 natural gas/air Cremer; 1975 995 43 151 801 4 via ammonia Lowenheim et.al.copper 63.5 copper ore Szargut; Boustead 1980 1537 130 n.a. 1407 9 methane 16 830 *) excluding steam-credit Figure 3 Graphical representation of the lost work analyses.Table 3 Minimum amount of input data required for the lost-work analysis of hydrogen production input compression power 0.02 kWh = 0.072 MJ natural gas* consumption 4141 kCal = 17.33 MJ water 1.78 kg output export steam 1.2 kg hydrogen 1 Nm3 *) natural gas is used both as feedstock and as energy source process, this rule is broken; hardly any fraction of the natural gas adopted as high quality raw material ends up in the nitric acid.Also, the direct use of high quality natural gas for low quality heating purposes does not coincide with the idea of sustainability.Towards sustainability In the discussion about how we should set up our chemical process industry in the (near) future, the sustainability issue is of prime importance. Sustainability in the ecological sense means that we do not place an intolerable load on the ecosphere and that we maintain the natural basis for F E AT U R E C G G178 Green Chemistry December 1999 This journal is © The Royal Society of Chemistry 1999 Efficient use of high quality resources Figure 4 shows lost work figures for the utilisation of natural gas for various purposes. From this picture it can be concluded that it is the best to use natural gas for those chemical processes in which it eventually ends up in the desired products. The basic rule behind this conclusion is that the degradation of work-potential has to be delayed as long as possible.This rule facilitates the choice of chemical route and raw materials. For the nitric acid The theoretical workpotential of natural gas A typical composition of Dutch natural gas is given in Table 2, which also presents its pure chemical work-potential. The average delivery pressure of Dutch natural gas is about 60 bara, representing a (physical) work-potential in addition, which is calculated as follows assuming ideal gas behaviour: Exfysical = R T0 .ln [ P P0 ] kJ/mol Since the natural gas is a mixture, the work-potential of mixing should be subtracted from the workpotential of the gas. Assuming ideal gas behaviour, this mixture-term is given by: Exmix = R T0 .S [yi ln yi] = 0.95 kJ/mol The total theoretic work-potential thus becomes 876 kJ mol–1. Conversion to normal cubic meters then gives a work-potential of 39.1 MJ Nm–3 (1 kmol gas = 22.4 Nm3). The ratio between the theoretical work-potential (Ex) of natural gas and its lower heating value (LHV) is thus 1.0455. Lost work analysis of hydrogen production based on steam reforming of natural gas Because the processes described in this paper are not simulated (rigorously), the accuracy with which the lost work analyses have been carried out is submissive to the quality of data available in public literature. Especially for processes involving intermediate products, e.g.the production of nitric acid from natural gas via ammonia, data from various sources have been merged making the analysis more complex than the hydrogen-case presented in this box.Nevertheless, the values indicated in Table 1 in the main text are fairly indicative. Here, we present the lost work analysis of a hydrogen production process. Table 3 gives the data applied, which are taken from Giacobbe et al. (1992). Hydrogen is produced by conventional steam reforming of natural gas; purification of the hydrogen product is done by pressure swing adsorption. Table 4 presents the results of the lost work analysis.From these results, the thermodynamic efficiency of hydrogen production is 10.53/18.26 = 0.58. The work-potential equivalent of export steam Export heat is given in the public literature in many ways. To convert the export steam— which is given in mass by Giacobbe et al.—to theoretical work-potential, it is assumed that saturated water at 60 bar (Tsat = 275 °C) is evaporated and superheated to 500 °C by process heat, thereby recovering work-potential.On the basis of the thermodynamic relation Exfys = DH 2 T0·DS and using data from the steam tables, this change of state results in an uptake of 1.06 MJ of workpotential per kg of steam. Figure 4 Lost work figures for the utilisation of natural gas for various purposes Table 2 A typical composition and the chemical work-potential of Dutch natural gas Chemical Composition work-potential *) Contribution Component mole% [kJ/mole] [kJ/mole] methane 90 830 747 ethane 8 1496 120 nitrogen 1.5 0.7 0.01 carbon dioxide 0.5 20 0.1 Total 100 867 *) based on the reference environment defined by Szargut et al., (1988)C G Green Chemistry December 1999 G179 This journal is © The Royal Society of Chemistry 1999 F E AT U R E Chemical routes The work-potential of chemical components can be calculated from thermodynamics. This work-potential can be considered as the minimum work needed to synthesize the specific component from constituents of its surrounding.It has been shown that in practice the production of desired chemicals requires far more work than indicated by the work-potential of this desired product. In other words, the work-potential entering and leaving such processes do not balance, so work is lost. The challenge of our process industry is to limit the losses, while still being able to let our processes run with sufficient speed.In past decades, increasing energyefficiency was accomplished mainly by complex heat-integration within existing chemical processes requiring considerable investments. The lost-work analyses described by Hinderink et al. (1996c), however, shows that the chemical reaction step largely determines the overall thermodynamic efficiency.Chemical reactions have been found by us to be a notorious source of lost work. If chemical processes are developed from scratch by state-of-the-art methods—i.e. by structured process synthesis procedures—attention can be paid to the core of the process, i.e., the chemical reactions or the chemical reactor. Then, a significant improvement of energy efficiency and process economics can be achieved simultaneously (Harmsen et al., 1999).Losses resulting from chemical reactions can be viewed similarly to losses resulting from heat exchange. The driving force for heat transfer is the temperature gradient, which not only determines the rate of transfer, but also the degree of devaluation of work-potential. Chemical reactions do also proceed along a gradient from high to low chemical affinity.On flowing along this gradient, heat is released and work-potential is lost. The relation between the Gibbs free energy of reaction and lost work is linear. This relationship has been established by Denbigh (1956) and was discussed by Hinderink et al. (1996b). This insight is of prime importance for the development of future chemical routes. For more sustainable chemical routes, chemical gradients should be reduced, or should be counterbalanced by chemical reactions proceeding against their gradient.In this view, there is an analogy between heat-pinch and reaction-pinch. Table 4 Lost work analysis of hydrogen production by steam reforming of natural gas* input natural gas 17.33 3 1.0455 = 18.12 MJex / Nm3 of hydrogen water negl.air negl. power 0.072 / hex (=50%) = 0.144 MJex / Nm3 of hydrogen Total = 18.26 output hydrogen 236 kJ/mole = 10.53 MJex / Nm3 of hydrogen steam-credit 1.2 3 1.06 = 1.27 MJex / Nm3 of hydrogen Total = 11.80 lost work 6.46 MJex / Nm3 of hydrogen 145 kJ/mole 72.4 GJ/ton *) for electricity/power production, an exergetic efficiency of 50% has been assumed (cogeneration process) life.The complexity of the chemical industry with its numerous products made that we have lost sight of the associated ecological impact of these products’ lifecycles: when you produce something, you also produce long-term effects. Improvement of thermodynamic efficiency is frequently but erroneously considered as the contribution to sustainability. An increase of thermodynamic efficiency, however, has to do with a lowering of the rate with which our non-renewable natural resources are consumed, whereas sustainability implies utilisation of renewable resources such as biomass or solar energy.Although the figures presented in this paper are quite indicative, they do not reflect the degree of sustainability of the processes but rather their efficiency.In other words, the degree to which they use renewable materials is not given explicitly. Actually, a chemical conversion process can be 100% efficient when all non-renewable work-potential (exergy) ends up in the desired product(s). In real processes, exergy is lost. Hence, more exergy enters the process than leaves it. This excess of exergy entering the process to make it proceed has to originate from renewable sources, such as solar exergy, in order to contribute to sustainability.Such a ‘balanced’ process industry can still lead to exhaustion of our natural resources if the exergy-content of the nonrenewable end-products is not utilized at the end of the product-life. If we go one step further, our starting materials should be renewable, e.g. carbon dioxide and water.Real sustainable systems/chains need to be circular with respect to matter (outputs become inputs). The driving force for such a sustainable system must stem from solar energy, which is essentially available in large quantity (Figure 5). Wall (1977) and Gong and Wall (1997) give elaborate discussions on exergy and sustainability. Looking into this matter more carefully, we have come to the insight that the extent to which a process contributes to sustainability can be characterised by three parameters.The first parameter is the one we have discussed before, the thermodynamic efficiency of the process. The second parameter needs to reflect the extent to which use has been made of renewable resources. Finally, a third parameter is needed to indicate the extent to which circles have been closed.For more details we refer to Van Den Berg et al. (1999). Figure 5 Flows of energy, exergy, and matter on earth (free from Wall, 1977)F E AT U R E C G G180 Green Chemistry December 1999 This journal is © The Royal Society of Chemistry 1999 Examples of reactions proceeding with a large gradient are the production of nitric acid by the partial oxidation of ammonia and the conversion of H2S into elemental sulphur and steam.The development of new chemical processes should thus focus on exergy-neutral reactions. In addition, one should also look for sophisticated utilisation of the Gibbs energy of reaction (Harmsen and Hinderink, 1999), e.g. by using it directly to drive a separation, i.e. reactive distillation.Of course, all future chemistry will still be submitted to the laws of nature. Renewable resources Although Figure 3 is fairly indicative, the graph lacks information on which part of the primary work-potential is renewable. If, for example, the energy needed for the metallurgical processes comes from hydro-energy, our conclusions with respect to the improvement-potential of these processes will have to be adapted.Conclusions Some general observations from lost work analyses are: l The extent of lost-work differs from product to product and from process to process and depends largely on how skilled we are. l Processes showing a large steam credit, although useful, should be distrusted, because this implicitly means that more primary work-potential is applied than actually needed.l All second law improvements basically have to come from postponing as long as possible the devaluation of workpotential; keep the quality of energy and matter high. In view of sustainability: l The best source for work-potential (exergy) is a renewable resource l A more complete thermodynamic analysis of processes does not only deal with the efficiency but also with the extent to which renewable resources have been used and to which extent ecological cycles have been closed.l An intuitive approach towards efficiency and sustainability is in our view unacceptable given the importance and urgency of these issues. Therefore, it is advisable to benefit from the quantitative power of the extended thermodynamic analysis proposed.References Berg, van den, M. M. D.; Kooi, van den, H. J.; Swaan Arons, de, J. (1999) A thermodynamic basis for sustainability, In ‘Proceedings of Efficiency, cost, optimization, simulation, and environmental aspects of energy systems, ECOS ‘99, June 8–10, Tokyo, Japan (Ed. Ishida et al.), pp. 270–275. Boustead, F.; Hancock, G. F. (1979) Handbook of industrial energy-analysis, John Wiley & Sons (New York).Cremer, H. (1980) Thermodynamic balance and analysis of syngas and ammonia plant, ACS Symposium Series, 122, ASME (Washington). Denbigh, K. G. (1956) The second law efficiency of chemical processes, Chem. Eng. Sci., 6(1), 1–9. Giacobbe, F. G.; Iaquaniello, G.; Loiacono, O. (1992) Increase hydrogen production, Hydrocarbon Process., 3, 69–72. Gong, M.; Wall, G.(1997) On exergetics, economics and optimization of technical processes to meet environmental conditions, in Proceedings of Int. Conf. on Thermodynamic Analysis and Improvement of Energy Systems (Ed. C. Ruixian), TAIES ’97 Beijing (China), pp. 453-460. Habersatter, K. (1991) Ökobilanz von Packstoffen stand 1990, Schriftereihe Umwelt, 132, BUWAL (Bern). Harmsen, G.J.; Hinderink, A. P.; Sijben, J.; Gottschalk, A.; Schembecker, G. (1999) Industrially applied process synthesis method creates synergy between economy and sustainability, 5th International Conference on Foundations of Computer-Aided Process Design (FOCAPD’99), July 18–23, 1999, Colorado, USA. Harmsen, G. J.; Hinderink, A. P. (1999) We want less: Process intensification by process synthesis methods, 3rd Int.Conf. on Process Intensification for the chemical industry, Ed. by A. Green, Publication No. 38, Antwerp, Belgium, October. 25–27., 1999, pp. 23-28. Hinderink, A. P.; Van der Kooi, H. J.; De Swaan Arons, J. (1996a) De exergie rekening: Veel chemische processen staan in het rood, Chemisch Magazine, 5, 191–193 (in Dutch). Hinderink, A. P.; Kerkhof, F. P.J. M.; Lie, A. B. K.; De Swaan Arons, J.; Van Der Kooi, H. J., (1996b) Exergy analysis with a flowsheeting simulator, Part 1: Theory; calculating exergies of material streams, Chem. Eng. Sci. 51(20), 4693–4700. Hinderink, A. P.; Kerkhof, F. P. J. M.; Lie, A. B. K.; De Swaan Arons, J.; Van Der Kooi, H. J. (1996c) Exergy analysis with a flowsheeting simulator: Part 2, Application: Synthesis gas production from natural gas, Chem.Eng. Sci., 51(20), 4701–4715. Lowenheim, F. A.; Moran, M. K. (1975) Industrial Chemicals, Wiley & Sons (New York). Pagani, G. (1982) New process gives urea with less energy, Hydrocarbon Process., 11, 87–91. Supp, E. (1985) Improved methanol production and conversion technologies, Energy Progr. 5(3), 127–130. Szargut, J.; Morris, D.R.; Steward, F. R. (1988) Exergy analysis of thermal, chemical, and metallurgical processes, Hemisphere Publishing Corp. (New York). Ullmann’s Encyklopaedie der technischen Chemie, 1981, band 20, Verlag Chemie (Weinheim). Wall, G. (1977) Exergy-a useful concept within resource accounting, Report No. 77-42, Institute of Theoretical Physics, Chalmers Univ. of Technology, Göteborg, Sweden. Wall, G. (1988) Energy flows in industrial processes, Energy 13(2), 197–208. Mr. A.P. Hinderink is currently a process engineer/consultant with Process Design Center B.V. where he is involved in many industrial process synthesis projects. He holds a Bachelor of Chemical Technology degree and a Master of Technological Design degree from the Delft University of Technology. The foundation of this paper was laid in 1994, when he worked with the group of professor De Swaan Arons. After a career of nearly 20 years in the industry, Jakob de Swaan Arons became a full professor at the Delft University of Technology. His specific interests are phase equilibria at high pressures and in the critical region, and the efficiency and sustainability of industrial processes. Hedzer van der Kooi has worked for more than 30 years in the Applied Thermodynamics and Phase Equilibria group within the Department of Chemistry at the Delft University of Technology. After several studies on phase equilibria, for example for natural gas processing, urea production and reversed micelles, he worked for about 10 years on process improvement and recently also on the definition and realisation of sustainability.

ISSN:1463-9262    

DOI:10.1039/a909915h

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

Three groups have recently independently published results on immobilised versions of TEMPO, which are effective in the oxidation of organic substrates. A group led by Hermann van Bekkum has developed a method for the anchoring of TEMPO via reaction of 4-allyloxyTEMPO with trichlorosilane, followed by grafting of the trichlorosilane onto MCM-41 (M. J. Verhoef, J. A. Peters and H. van Bekkum, (Stud.Surf. Sci. Catal., 1999, 125, 465). The catalyst was then tested in the oxidation of an amethyl glucoside: The best results were obtained with sodium hypochlorite. At pH 9, the usual conditions with this oxidant, significant destruction of the base-labile MCM-41 framework was observed, and it was necessary to reduce the pH to 8. Lowering the temperature to 0 °C was also required to control the poorer selectivity of the reagent at this pH.Under these conditions, no leaching occurred. In the same paper the authors also report the oxidation of benzyl alcohol to benzaldehyde with excellent selectivity using the same TEMPO catalyst with an oxygen / CuCl / immobilised TEMPO system. Meanwhile Carsten Bolm and Thomas Fey (Chem. Commun., 1999, 1795) reported the synthesis of a similar material from aminopropylsilica and the 4-keto derivative of TEMPO, via a reductive amination sequence.This was shown to be an efficient catalyst for the oxidation of primary alcohols to aldehydes, and a reasonably effective oxidant of secondary alcohols. The primary oxidant used was sodium hypochlorite and potassium bromide. Reuse of the catalyst was also demonstrated, with little change in activity over 10 reuses.In a related publication (Stud. Surf. Sci. Catal. 1999, 125, 237) Daniel Brunel’s group have demonstrated the use of peptide coupling techniques to prepare anchored TEMPO, again via aminopropyl- derivatised Micelle Templated Silica (MTS). Thus, they showed that stably bound amides can be produced using dicyclohexyl carbodiimide or N-hydroxy succinimide derivatives of carboxyTEMPO.They also provided an elegant method to determine whether the TEMPO units are genuinely bound to the surface. This involves the use of tetrafluoro-TCNQ as an electron acceptor. Chemically bound TEMPO units give charge transfer bands on interaction with the TCNQ derivative. However, physically adsorbed or free TEMPO moieties do not give these charge transfer bands.Thus the colour of the solid after treatment with the TCNQ is a direct and simple indication of the nature of the attachment of the TEMPO units. Such a test will help determine the effectiveness of the coupling at the surface in such catalysts. MCM-41 as catalyst support MCM-41 has also been used as a support for two other interesting new catalysts for oxidation.A group led by Steven Ley and Brian Johnson has demonstrated the utility of an immobilised form of ammonium perruthenate (Chem. Commun., 1999, 1907). They immobilised the catalyst by protonation of the aminopropyl-MCM41 material with HBF4, followed by exchange of the anion with potassium perruthenate. The catalyst obtained is very active for the conversion of several benzylic and allylic alcohols, giving quantitative yields of aldehyde or ketone in short reaction times using air as oxidant.Other catalysts derived from trialkylamines and bromopropyl-MCM-41 followed by ion exchange were also tested and found to be equally effective. Chi-Ming Che and co-workers have described their work on the asymmetric epoxidation of alkenes using a supported binaphthyl-Schiffs base complex of Cr, which they have immobilised on aminopropyl-MCM-41 (Chem.Commun. 1999, 1789). Metal-free oxidations C G Green Chemistry December 1999 G181 This journal is © The Royal Society of Chemistry 1999 P E R S P E C T I V E SImmobilisation of the Cr complex was achieved under mild conditions, and the complex was used to carry out the epoxidation of a range of alkenes using PhIO as oxidant.Whereas many immobilised chiral complexes lead to lower enantioselectivities than their homogeneous counterparts, in this case ee’s were substantially higher (e.g. for 4-chlorostyrene the immobilised catalyst gave 65% ee, while the homogeneous equivalent gave only 48%). The recycling of the catalyst was partially successful, with two uses giving identical results, the third slightly poorer, and the fourth substantially worse.Total turnover numbers were over 200 with good ee, then an additional 77 turnovers could be achieved at lower ee. The increase in ee is unusual and interesting, especially in light of the opportunities for control of the pore size and surface chemistry which is possible with such supports.Hydroformylation of alkenes The hydroformylation of alkenes continues to be a fertile area for catalyst innovation. The Ruhrchemie-Rhône- Poulenc process (based on a watersoluble phosphine-Rh complex) is an excellent example of this (see, for example, CHEMTECH, 1987, 570). However, it is limited to low molecular weight alkenes. Peter Wasserscheid and co-workers from the RWTH-Aachen have developed a novel methodology based on ionic liquids to get round this problem (J.Catal., 1999, 186, 481). They studied the hydroformylation of methyl 3-pentenoate, a potential new intermediate for the production of adipinic acid and nylons. They found that excellent reactivity and selectivity could be obtained in the ionic liquid reaction media.Furthermore, the lack of volatility of the ionic liquid, coupled with its good thermal stability, meant that the products could be distilled out of the reaction system, leaving the catalyst dissolved in the ionic liquid. This solution could be reused directly in a second reaction. Further reaction cycles led to a slow deactivation. However, using conventional solvents, the catalyst is left in the distillation residues (if it is not extracted first, a difficult and inefficient step) and can no longer be used after the first cycle.These initial results indicate that the catalyst lifetime can be readily increased by the use of ionic liquids, without a change in selectivity. Such an innovation improves both the environmental impact of the process and its economics.Hydrogenation of ketones The enantioselective heterogeneous hydrogenation of ketones has been studied by several groups over the last decade or so. The most promising system involves the use of Pt/alumina modified with naturally occuring alkaloids such as cinchonidine. These systems can deliver excellent enantioselective excesses in the hydrogenation of a range of ketones to alcohols.Alfons Baiker and his group have now demonstrated that a continuous hydrogenation of activated ketones such as ketopantolactone and ethyl pyruvate is possible if the chiral modifier chinchonidine is fed continuously into the reactor at ppm levels. (J. Catal., 1999, 126, 239) Interestingly, the addition rate required for optimum ee was dependent on the type of reactor used, but other operating parameters had less influence.The enantioselectivity achieved was 83.4% for the lactone and 89.9% for the less reactive ethyl pyruvate. Energy-efficient microwave synthesis French scientists at the IUT Département Chimie, Besançon, have been comparing the effects of microwave irradiation and classical heating on the intramolecular cyclisation of 2-hydroxyphenylacetic acid (J.Chem. Soc., Perkin Trans. 2, 1999, 2111). By using an optical fluorescence technique, Jean Marie Mélot and colleagues were able to make accurate measurements of local temperatures in the reactor (Figure 1). Although they found no intrinsic difference in reaction rates using the two different heating methods, they did conclude that the transfer of energy to the reaction was much more efficient under microwave conditions: the whole reaction process required just 108 kJ using microwaves, whereas the classically heated reaction consumed over 3500 kJ.Hydroxylamine oxidations using bleach Nitrones are useful building blocks in organic synthesis, but are commonly pro- P E R S P E C T I V E S C G G182 Green Chemistry December 1999 This journal is © The Royal Society of Chemistry 1999duced by oxidation of hydroxylamines using highly toxic mercury salts, or other heavy metal reagents.Research conducted by Andrea Goti and co-workers at the Universitá degli Studi di Firenze in Italy has led to a new method for hydroxylamine oxidation which is much more environmentally acceptable (J. Org. Chem., 1999, 64, 7243). A wide range of substituted nitrones were prepared in high yield (50–92%) by reaction of hydroxylamines with aqueous sodium hypochlorite solution at room temperature, with the yields and selectivities being comparable to those obtained using HgO.Household bleach was found to be just as effective for this transformation as commercially supplied 13% sodium hypochlorite. Direct synthesis of iodoalkanes Dr Peter Schreiner and colleagues at the Institut für Organische Chemie der Universität, Göttingen, Germany, have discovered a simple and efficient method for the direct iodination of unactivated hydrocarbons (Angew. Chem., Int.Ed., 1999, 38, 2786). Unlike other free-radical halogenation reactions, iodinations are markedly endothermic, which prevents a chain reaction occurring, and so iodoalkanes had to be prepared by reaction of an alcohol or another haloaromatic.The new reaction involves simply stirring the unfunctionalised alkane with sodium hydroxide and iodoform at room temperature, either without a solvent if the alkane is liquid, or in dichloro-methane for heavier solid substrates. Yields vary considerably, but are in the 70–95% region for several substrates.Polyurethanes Since polyurethanes were first produced 60 years ago they have been prepared by mixing two chemical components, and the plastics are actually formed in the moulds of the upholstery or shoe-sole manufacturers etc. Now, chemists E. W. Meijer, Ron M. Versteegan and Rint P. Sijbesma, at the University of Eindhoven (Angew. Chem., Int. Ed. 1999, 38, 2349–2354), have now found a way to include both polyurethane components in one and the same molecule; these building blocks can be used to easily construct types of polyurethane that could only be synthesised in a roundabout way before.The basic building blocks of polyurethanes are molecules that contain alcohol and isocyanate groups. In principle these groups act as ‘button’ and ‘buttonhole’; the building blocks, which each have either two buttons or two buttonholes, automatically link together in a reactor to form long chains.Clearly, it would be easier to include both ‘button’ and ‘buttonhole’ in the same molecule, so only a single type of building block would be produced. This already works in the synthesis of the related polyamides (Nylon, Perlon), which are constructed in a similar fashion—only starting from acids and amines.Until now, complicated tricks had to be used to get this to work for polyurethanes, because the crucial isocyanates could only be synthesised under conditions that are unfriendly to the alcohols, causing them to undergo other reactions. This is where the team from Eindhoven comes in—they found a chemical that builds up isocyanates in a very gentle way, under conditions that leave any alcohol groups in the molecule untouched.In this way, Meijer and his coworkers could actually produce polyurethanes that contain only one type of building block. The physical characteristics of these [n]polyurethanes are very promising. Whether they will be accepted in industry, however, mainly depends on whether the simple building blocks can easily be produced in large quantities.Diols At the Institute of Organic Catalysis Research in Rostock, Matthias Beller, Christian Dobler and Gerard Mehltretter have been able to produce diols (used as antifreeze, as basic building blocks for a variety of plastics, and in the synthesis of many pharmaceuticals) in a single step from oxygen and olefins (e.g.ethylene or propylene) using osmium compounds as catalysts (Angew. Chem., Int. Ed. 1999, 38, 3026–3028). Currently diols are synthesised in two steps. Indeed it has been known for some time that diols could be synthesised from C G Green Chemistry December 1999 G183 This journal is © The Royal Society of Chemistry 1999 P E R S P E C T I V E S Figure 1 Measurement of local temperatures by optical fluorescenceolefins in one step when osmium compounds are used as a catalyst.Industry has not been able to make use of these one-step processes, however, because they required large quantities of expensive oxygen-containing specialty chemicals, whose synthesis generated large quantities of waste. The new Rostock process. By using oxygen gas, is both highly economical and more environmentally friendly.Beller’s team is not the first to experiment with oxygen and osmium; earlier attempts, carried out by other chemists decades ago, under aggressive conditions, led to the destruction of the newly-formed diols by the metal and the idea was abandoned. Catalyst for air purification A room temperature catalyst for efficiently converting carbon monoxide into carbon dioxide has been developed by Graham Hutchings and Stuart Taylor of Cardiff University working with Ali Mirzaei at the Leverhulme Centre for Innovative Catalyst at the University of Liverpool (Chem.Commun., 1999, 1373). The catalyst, the first room-temperature catalyst based on copper zinc oxide for oxidising carbon monoxide, could be used in more effective and cheaper-to-run air purifiers at industrial sites, in mining and for deep sea and space exploration to avoid carbon monoxide poisoning.The catalyst is far more effective than the commonly used hopcalite (mixed manganese copper oxide) catalyst, although its structure must now be optimised. The team prepared their catalyst using co-precipitation under different gases—air, nitrogen, hydrogen and carbon dioxide.Each preparation effectively mixes copper(II) oxide and zinc oxide to form a highly dispersed mineral containing a ‘solid solution phase’. Composition depends on preparation gas, the ageing between preparation and filtering the solid from the liquid. The catalysts were tested for carbon monoxide oxidation power at 20 °C under a steady flow of carbon monoxide.All the copper zinc oxides were highly active, but the most active were those prepared in air and aged for one hour. The team is now studying the mechanism of oxidation more closely with a view to optimising the preparation conditions. Ionic liquids continue to impress Ionic liquids are currently attracting considerable attention as green solvents.The properties of ionic liquids that make them potentially green include their ability to dissolve many different chemicals, including rock and coal, and the fact that they are non-volatile, inflammable and are non-toxic. Professor Claude de Bellefon and his team at the Laboratoire de Génie des Procédés Catalytiques in France have recently discovered other properties of ionic liquids that may lead to greener chemical processes in the near future.The team compared ionic liquids with water as catalyst support media in ‘liquid–liquid’ biphasic catalysis (J. Mol. Catal. A: Chemical, 1999, 145, 121). They studied the palladium catalysed Trost-Tsuji C–C coupling reaction (see Scheme) and apart from the ease of separation of the catalyst (also true of the water system) found the following advantages over the water system. The ionic liquid dissolves the organic reagents to a greater extent than water, which means that a higher substrate/catalyst ratio can be used and the reaction rate is enhanced. Palladium chloride is soluble in the ionic liquid and can therefore be used as the Pd(0) precursor instead of palladium acetate. Formation of cinnamyl alcohol (a side-reaction involving water as a nucleophile) is suppressed, and furthermore, simple alkane co-solvents can be used as in place of nitrile solvent required in the aqueous regime. Further work is in hand to use this chemistry in a continuous reactor to evaluate the catalyst deactivation and the product separation. P E R S P E C T I V E S C G G184 Green Chemistry December 1999 This journal is © The Royal Society of Chemistry 1999 Read any green chemistry papers? If you have any items from your literature reading which could be included in the PERSPECTIVES section of Green Chemistry, please send them to James Clark or Duncan Macquarrie [email: greenchem@york.ac.uk; FAX: +44 (0)1904 434533 or +44 (0)1904 423559]

ISSN:1463-9262    

DOI:10.1039/a909916f

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

Green Chemistry December 1999 G185 This journal is © The Royal Society of Chemistry 1999 C G E V E N T S Alternative ways of turning green into gold ndustry, agencies and Governments throughout the EU are committing effort and resource to the development of new technologies needed to support major changes in raw material sourcing. The latest conference, GRIF’99, at the John Innes Centre, Norwich, UK, in November—organised by ACTIN, the leading authority in the UK on industrial crops—has recently identified ‘drivers for change’ in the move towards greater reliance by industry on crop-derived raw materials.Although more than 80% of the world’s energy and raw material needs are currently derived from mineral oil, gas and coal, there are increasing concerns in industry and government over the sustainability of a reliance on fossil resources; particularly, the impact of this on the level of CO2 in the atmosphere, which is seen as a major contributor to the greenhouse effect.Farmers already have a small part to play in reaching this target by supplying biomass in the form of farm and crop residues and short rotation coppice for electricity generation.However, plants, which use the sun’s energy to convert CO2 into polysaccharides and other complex molecules, also have tremendous potential to become a renewable source of high quality raw materials for industry. Delegates at GRIF’99 learnt about new aspects of research in starch metabolism and the underlying genetics in cereals, new polymers and plastics being developed by industry, composite materials for the automotive and building industries and the potential to produce speciality chemicals and high added value products in plants including milder detergents, inks, dyestuffs and agrochemicals.Of particular note was ICI’s biodegradable product Eco-Foam, made from modified maize starch. This has the same soft resilient features as polystyrene but, unlike the conventional product, it dissolves in the presence of water.Eco-Foam, or the Novamont (Italy) product Mater-Bi which has complementary properties, could replace huge tonnages of long-lived plastic packaging made from fossil fuels and destined for landfill. Earlier this year, the aptly named ‘Oilseed Rape Pipeline’ seminar was the first crop-based seminar held by ACTIN (Alternative Crops Technology Interaction Network).Oilseed rape is probably the most developed of the industrial, i.e. non-food, crops in the I UK and, accordingly, there were diverse papers ranging from Warwick University to Mobil Oil Company. The seminar attracted 70 delegates from a wide variety of backgrounds who debated the rapidly improving scientific understanding of possible genetic, chemical and physical modifications to the crop and its current and potential uses as a renewable raw material for industry.Oilseed rape is now the third most important crop in the UK after barley and wheat with nearly 500,000 hectares under cultivation. Globally, it is ranked as the third most important oilseed crop after soybean and palm. University research in the UK on the crop’s metabolism is world class and on par with the US.Current research programmes, funded by Home-Grown Cereals Authority (HGCA), into physicochemical modifications are highlighting the versatility of the crop and the potential importance of rapeseed oil as a feedstock for polymers and oilseed rape meal in biocomposite manufacture. Croda, an industrial user of high erucic rape oil (HERO) for erucamide production, described the extensive collaboration which took place over a period of years with British farmers, MAFF and European authorities to re-establish HERO as crop grown in the UK for industrial users.Rapeseed oil-based polyols have also been successfully introduced in rigid polyurethane systems, currently being used in commercially-acceptable production of moulded parts for the automotive industry, with resultant environmental and financial advantages.Manufacturing plants for rigid foam polyols derived from natural oils are now being sold worldwide, particularly to Eastern Europe and the Asia Pacific regions. There is also the prospect of high functionality foams 100%-derived from rapeseed oil feedstocks. Oilseed rape based oils have developed a niche position in the UK lubricants market but despite having some intrinsic advantages in their environmental impact, they have not fulfilled their potential, partly due to a lack of legislation. The economic and environmental viability of the pipeline is being addressed through detailed ‘whole systems’ approaches, e.g.Lifecycle Oilseed rape and wheat— two crops where industrial uses are being explored.E V E N T S C G G186 Green Chemistry December 1999 This journal is © The Royal Society of Chemistry 1999 (LCA) and Cost Benefit Assessment (CBA) studies.Agenda 2000, the most recent reform of the EU’s Common Agricultural Policy, is effectively removing the oilseed premium from the farming industry. However, this should not have a significant effect on the supply of oilseeds within the UK/EU as the crop will have an important long term role in balanced arable rotations. Alternatively, any perceived long-term supply insecurity could be overcome with stable, fixed-price supply contracts.In conclusion, the seminar noted that manufacturers can be confident of: l a secure supply of raw material l at a competitive ‘crude oil’ price l which can satisfy market expectations l for a number, perhaps an increasing number, of non-food applications Baroness Hogg, who is Chairman of a House of Lords Science and Technology Sub-Committee inquiring into non-food crops, which will be reporting in December, recently wrote (Financial Mail on Sunday, 5 September 1999): ‘Today, or at least tomorrow, we will be able to grow all kinds of valuable compounds that at present we manufacture synthetically.These range from vaccines to packaging materials. There is great environmental advantage to be gleaned from such natural production, from the use of biodegradable rather than synthetic materials. These have to be balanced against the use of genetic techniques that might be needed to make some of these products viable.There are no magic solutions here to the troubles of the agricultural sector, to reform of CAP, to environmental policy or to the needs of the rural economy. But there is potential for the enterprise culture to play its part in the resolution of these difficulties.’ Industry is also recognising the importance of sustainability in the 21st Century and the enormous variety of opportunities arising from renewable feedstocks.Dr. Robert R. Dorsch, director of biotechnology development at DuPont, has stated, ‘Essentially all of society in the last 100 years has been built on petroleum as the energy and raw material. We need to go from black gold to green gold’. For its own part, ACTIN has planned a strategic calendar of relevant events for 2000, including ‘Industrial Uses of Wheat’ (Cambridge, 22 March 2000) with speakers including DuPont and Hunstman Polyurethanes.The Oilseed Rape Pipeline and GRIF proceedings are available from the ACTIN Help Desk, Tel +44 (0)1372 802054, E-mail info@actin.co.uk, www.actin.co.uk; as are further details of ACTIN itself - a ‘not for profit’ organisation - their 2000 calendar and a ‘Report of Activities 1997-1999’ Nigel Oliver, ACTIN, 15 November 1999.York Green Chemistry Symposium The Green Chemistry Network held a one-day symposium at the end of September 1999 in York. The symposium, which was kindly sponsored by Zeneca Agrochemicals, brought together younger workers in the field from local universities to discuss their work.One of the main aims of the symposium was to demonstrate the interdisciplinary nature of green chemistry and to encourage a ‘team’ approach to solving real issues. Topics covered during the symposium included heterogeneous catalysis, process intensification, supercritical fluids and ionic liquids. Full details of all the speakers and abstracts of the presentations can be found on the GCN web site http:/www.chemsoc.org/gcn.Karen Wilson, who has been working with James Clark for several years and has recently been appointed as a lecturer at York started the day with a paper on ‘New Solid Acids For Organic Synthesis’. The talk centred around the use of mesoporous silica functionalised with Lewis [BF3, AlCl3, Zn(OTf)2] and Bronsted acids (RSO3H) for carrying out industrially important organic transformations.Specific examples included alkylation, etherification and isomerisation of aromatics. These reactions are often carried out by acids which are not recovered at the end of the reaction and are major contributors to waste streams generated by the fine chemicals industry. Helen Theyers, a Ph.D. Student from Hull working with Adam Lee, continued the heterogeneous catalysis theme.Heterogeneously catalysed oxidation reactions for fine chemicals synthesis is advantageous because this can avoid the production of environmentally unacceptable waste produced by traditional stoichiometric methods, facilitate use of simple clean oxidants, e.g. air and H2O2, and simplify product separation. The selective oxidation of cinnamaldehyde and cinnamaldehyde over carbon supported PGM catalysts and the effect of promoter, support, solvent and temperature were discussed.Cinnamaldehyde oxidation proved difficult giving poor yields. Greater selectivity was obtained using prereduced catalysts, and surprisingly unpromoted catalysts were more selective. Selectivity decreased with temperature as combustion commenced. Speakers at the York Green Chemistry Symposium, left to right: Karen Wilson (University of York), Matthew Giles (University of Nottingham), Helen Theyers (University of Hull), Keith Gray (Nottingham), Kamelia Boodhoo (University of Newcastle), Rajiv Bhalla (University of York), Nicola Meehan (University of Nottingham).C G Green Chemistry December 1999 G187 This journal is © The Royal Society of Chemistry 1999 E V E N T S Cinnamyl alcohol oxidation to cinnamaldehyde resulted in much higher conversions (18%) with 98% selectivity.For both reactions carbon supported catalysts appear more selective than graphite counterparts. Chemical engineering has a huge role to play in green chemistry; the most Eco-friendly processes of the future will undoubtedly be developed by chemists and engineers working together.Kamelia Boodhoo, a post-doctoral fellow in the Process Intensification & Innovation Centre at Newcastle University gave a talk on spinning disc reactors (SDR) and how they can be used to both drastically reduce the size (and cost) of processing equipment and improve process efficiency. SDR’s are a potentially attractive choice of reactor for systems which are or become heat or mass transfer limited, e.g.polymerisation reactions or inherently fast reactions. Possible applications in polyester and polystyrene manufacture were discussed; advantages of the SDR in these applications include lower energy use and production of more controlled narrower molecular weight distribution. Advantages and applications of supercritical fluid technology were explored in three presentations from Nottingham University. Nicola Meehan gave an overview of supercritical fluid technology; making the highly valid point that even though use of scCO2 offers many environmental advantages as a benign replacement for more toxic solvent, due to the cost of high pressure equipment, it is only likely find applications where there are technical as well as environmental benefits.Nicola’s presentation centred on development of supercritical hydrogenation technology in conjunction with Thomas Swan. This technology opens up the possibility of having small ‘on demand’ hydrogenation reactors of interest to fine chemicals manufacturers. The same technology is also showing promise for dehydrogenation reactions.Matthew Giles presented a paper on stabilisers for polymerisation in supercritical carbon dioxide, an area which has received much attention since DeSimone’s Science paper in 1992. Dispersion polymerisation of acrylates in scCO2 suffer from production of low molecular weight material due to polymer insolubility. By adding stabilisers, which have a scCO2 soluble group such as siloxane or fluorocarbon as well as an acrylate soluble moiety, the polymer can be stabilised until much higher molecular weights have been built up.By varying the length of siloxane chain for example some control over polymer morphology, molecular weight and yield can be exerted. More efficient and Eco-friendly ways of carrying out Friedel–Crafts reactions was a recurring theme during the day.Keith Gray highlighted the contribution supercritical technology is able to make in this area. In the reaction of phenol with an alkylating agent the reaction can be tuned to give preferential C or O alkylation. Using similar technology the Nottingham group have also investigated the synthesis of cyclic ethers; in particular an improved method for the synthesis of THF from 1,4-butanediol has been studied. Dr Rajiv Bhalla, Postdoctoral fellow working with Paul Dyson at York gave a presentation covering hydrogenation reactions using novel biphasic approaches. The design and synthesis of a variety of chiral phosphine ligands was described and there use with Ru and Rh based catalysts in ionic liquid–organic and ionic liquid–water biphasic systems for carrying out a variety of organic transformations discussed.Ionic liquids clearly increase the activity of catalysts of this type and offer high potential for highly selective waste-free processes. The keynote presentation was given by Professor Ken Seddon of Queen’s University, Belfast. Ken is well-known as a leading expert in the field of ionic liquids and gave an extremely interesting overview of the potential applications and environmental benefits ionic liquid based processes may offer.The potential number of ionic liquids available is truly enormous and current research has hardly scratched the surface, by tailoring the components the property of the liquid can be varied widely. The environmental benefits largely result from the avoidance of volatile organic solvents; ionic liquids however also offer many technical advantages including: l large liquid range (ca. 300 °C). l thermal stability l Bronsted, Lewis and Franklin acidity l excellent solvent properties Potential industrial applications of ionic liquids include alkylation, acylation, polymerisation and catalysis of Diels–Alder reactions. Also at the meeting the RSC Process Technology Group presented their Award for Clean and Efficient Processing to BP Amoco for the CATIVA acetic acid process.Accepting the award Dr Derek Watson described how this new methanol carbonylation technology using, an iridium catalyst, reduced the E-Factor by some 30% through improving energy efficiency and reducing liquid waste byproducts (propionic acid). Carbon dioxide emissions have been reduced from 0.48 te / te acid to 0.318 te / te acid.It world production of acetic acid were converted to CATIVA the saving would be 270,000 tpa CO2 compared to the Monsanto process. Apart from environmental benefits there is also a saving of some 30% on the cost of new plant. Mike Lancaster Corporate Environmental Leadership Seminar The ninth annual Corporate Environmental Leadership Seminar will be held June 4–15, 2000 at Yale University in New Haven, Connecticut.As the leading executive program of its kind, the Corporate Environmental Leadership Seminar offers a comprehensive curriculum emphasizing Emerging Issues and Environmental Leadership Development. The 2000 Seminar features many new sessions designed to provide essential information and sharpen decision-making tools for the difficult tasks facing senior environmental managers. Case studies, discussions, and exercises highlight the cross-disciplinary aspects of environmental problem solving, in view of conflicting scientific analyses and changing conditions. The curriculum is divided into three clusters: l Science for Environmental Management and Policy l Law, Economics & International Environmental Management l Environmental Leadership in a Time of Change A small class size encourages exchange among a diverse group of participants representing government agencies, non-governmental organizations and a broad range of private business. For more information, contact Michelle Portlock, Program Coordinator, The Corporate Environmental Leadership Seminar, Yale School of Forestry and Environmental Studies, Tel: +1 (203) 432-6953; Fax: +1 (203) 432-5556; Email: michelle.portlock@yale.edu; http://www.yale.edu/cels.

ISSN:1463-9262    

DOI:10.1039/a909917d

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

C G G188 Green Chemistry October 1999 This journal is © The Royal Society of Chemistry 1999 January 2000 2nd Asia-Pacific Congress on Catalysis January 31 Sydney, Australia –February 2 (http://www.chemsoc.org/events/_events/ 00001018.htm) February 2000 AAAS Annual Meeting and Science February 17–22 Innovation Exposition including a workshop on Sustainability through Science Washington DC, USA (http://www.aaas.org/meetings/2000/index.htm) Hazard Analysis in Chemical Industry February 27 (HACI) and Inherently Safer –March 1 Plant Design (ISD) Kanpur, India (jpg@iitk.ac.in) March 2000 Process Design and Operation for March 5–9 Sustainable Development The Hilton Hotel, Atlanta, USA (http://www.cpe.surrey.ac.uk/staff/aa.htm) Green Chemistry March 15 University of York, UK (http://www.chemsoc.org/events/_events/00002021.htm) Biocatalysis as a tool for organic synthesis March 20–22 Crowne Plaza Hotel, Amsterdam, The Netherlands (http://www.scientificupdate.co.uk/pages/biocatalysis/ biocat.html) Industrial Uses of Wheat March 22 The Chilford Halls, Cambridge, UK (info@actin.co.uk) INBIO Europe 2000: Biocatalysis— March 23–24 New Science and Applications Crowne Plaza Hotel, Amsterdam, The Netherlands (http://www.scientificupdate.co.uk/pages/inbio/inbio.html) Teaching the Environmental Sciences in March 25 the Millennium Including a session on Green Chemistry Scientific Lecture Theatre, Burlington Place, London, UK (greennet@york.ac.uk) ACS National Meeting including Green March 26–31 Chemistry for Reduction of Greenhouse Gas Emissions San Francisco, California, USA (http://www.lanl.gov/greenchemistry/conf.htm) Conference Diary April 2000 Green-Tech®2000— April 3–5 Sustainable Raw Materials Royal Dutch Jaarbeurs, Utrecht, Netherlands (http://www.europoint-bv.com) Hazards XV- The process, its safety, and the April 4–6 environment - getting it right UMIST, Manchester, UK (mikeadams@valrichardson.com) 5th International Symposium on April 8–12 Supercritical Fluids: ‘Supercritical Fluids for Sustainable Technology’ Westin Atlanta North Hotel, Atlanta, Georgia, USA (http://www.issf2000.org) Wood and Cellulose: Building Blocks April 9–12 for Chemicals, Fuels and Advanced Materials SUNY-EST, Syracuse, New York, USA (http://www.epa.gov/opptintr/greenchemistry/calendar.htm) Rapid Process Development and Safe April 12 Process Scale-Up North London, UK (http://www.helgroup.co.uk/index.cfm/page.news) CAPoC5—5th International Congress on April 12–14 Catalysis and Automotive Pollution Control Université Libre de Bruxelles, Belgium (http://www.ulb.ac.be/sciences/surfcat/CAPoC5/) 9th International (and 4th European) April 13–14 Symposium on Supercritical Fluid Chromatography and Extraction.In cooperation with Analytica Conference 2000 Munich, Germany (sfc2000@mx.uni-saarland.de) RSC Annual Conference including April 16–20 Symposium ‘Towards Sustainability’ UMIST, Manchester, UK (http://www.rsc.org/lap/confs/sciprog.htm) InLCA: The International Conference and April 25–27 Exhibition on Life Cycle Assessment Cincinnati, USA (InLCACI@epamail.epa.gov) May 2000 Synthetic Methodology and May 16 Total Synthesis: New Horizons in Natural Product Chemistry University of Glasgow, UK (http://www.rsc.org/lap/rsccom/dab/perkidiv.htm) 16th Canadian Symposium on Catalysis May 23–26 Banff, Alberta, Canada (http://www.gch.ulaval.ca/~sayari/16csc/) D I A R Y

ISSN:1463-9262    

DOI:10.1039/a909918b

出版商:RSC    

年代:1999

数据来源: RSC