摘要:

Editorial Green Chemistry C G Green Chemistry October 1999 G117 This journal is © The Royal Society of Chemistry 1999 he number of applicants this year to read chemistry in UK Universities fell to 19257—representing a decrease of some 9.2% on the previous year. In my experience there are similar trends in many countries in Europe and elsewhere. Should we be concerned and can green chemistry affect this trend? I have heard it said that this is not a problem since the industrial demand for chemists in many parts of the world is also falling. Germany for example went out of equilibrium in the early 1990s when its previously buoyant chemical industry cut right back on its high recruitment levels for graduate chemists. This created a ripple effect as large numbers of German chemistry graduates sought employment in other countries.I have spoken to company managers in the UK who report high proportions of job applicants from France and Italy for example and I am aware of the increasing numbers of students from mainland Europe now seeking PhD places in the UK. Of course an increase in graduate mobility is to be applauded and if the number of qualified chemists on the market reduces then salaries may well be driven upwards which in turn might encourage more students to read chemistry and related subjects. However if instead of simply considering the changing market requirements for graduate chemists we consider the reasons for the reduction in student application numbers then I believe that there is a real and immediate cause for concern. The choice of university subject is certainly influenced by career opportunities and financial reward (although we must remember that we want chemistry graduates in more walks of life than the chemicals and related industries and academia!) but it is also heavily influenced by interest and perceived reputation and status.Over many years chemistry has attracted many able young minds because it was seen as a challenging and interesting subject of real value to society. Unfortunately chemistry seems mostly to grab the headlines these days as a result of a disaster rather than an invention or benefit to society. If we are to continue to attract bright young people into chemistry and to encourage a wider participation in chemical subjects then we must address the fundamental issue of subject image. So how can green chemistry help? Young people are instinctively interested in environmental issues.If the apparent environmental aspects of chemistry are negative i.e. chemistry is considered to be damaging to the environment then many young people will be antagonistic towards the subject. On the other hand we can attract students if we emphasise the vital role chemistry has to play in understanding our environment and how the principles of green chemistry are being used to better manage the environment and to provide the lifestyle we want at minimum cost to the environment. How can we do this? We must first realise that you cannot start too early! Even before students are taught chemistry as a distinct subject they can learn about green chemistry aspects of environmental issues. It is important that our children are brought up believing that chemistry is for the environment not against it! Once students start studying chemistry and start carrying out chemical experiments then we have a growing number of examples case studies and experiments that can be used to teach good practice.We have been able to publish a lot of relevant material in Green Chemistry but T we need more good examples. Practical classes are excellent vehicles for teaching green chemistry. Most of us will have gone through an undergraduate practical course with synthetic experiments that were based on the principle that the end justifies the means—obtaining a pure product was the essential goal. We should expect our students to calculate not only the product yield but also the atom efficiency the solvent usage and the waste as well as at a later stage in their course the economic and environmental feasibility of the method. If you know of such examples of green chemistry experiments then please let us know so that we can share them with the chemistry community. We should aim to make our students aware at an early stage of an educational version of the triple bottom line better chemistry better education and better environment! James Clark York September 1999 C G G118 Green Chemistry October 1999 This journal is © The Royal Society of Chemistry 1999

ISSN:1463-9262    

DOI:10.1039/a908644d

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

C G Green Chemistry October 1999 G119 This journal is © The Royal Society of Chemistry, 1999 N E W S Activated carbon from nuts A team of scientists led by Wayne Marshall at the USDA-ARS Commodity Utilization Research Unit located at the Southern Regional Research Center, outside New Orleans, USA, are recycling nut shells into activated carbon. Christopher Toles, formerly with ARS but now with Northeastern University in Boston, Massachusetts, is also involved in the research.The shells are ground and exposed to temperatures of up to 900 °C in combination with steam, certain gases, or acids. Such treatment activates, or opens, millions of microscopic pores in the carbonised shells, enabling them to hold on to chemical molecules. Oxidation confers a negative charge to the shells, helping them to capture metal ions in solution.Various nut shells have been tried, including pecan and almond, but so far the activated carbon from macadamia nut shells has been found to adsorb the broadest range of organic molecules. It is estimated that 14,600 tons of macadamia shells could yield about 3000 tons of activated carbon material. In one comparative study with 6 commercial adsorbents, use of activated macadamia shells led to a 3- to 4-fold increase in the ability of a standard Environmental Protection Agency air sampling procedure to detect benzene at concentrations of 100 parts per billion. The nut shell carbon also performed well in small-scale studies to remove copper from industrial waste water.The potential of the carbon as an adsorbent material for gas chromatographic analysis of air is particularly encouraging.To foster commercial collaboration, the team has applied for patent protection on its activation procedures. Other nut shells are being investigated, such as hazelnuts, black walnuts and Brazil nuts, as sources of activated carbons. Today’s usual activated carbons are made from coal, peat, coconut shells and wood. The nut shells represent a renewable low-value agricultural waste source of activated carbons, widely used to adsorb many organic compounds from air or water. MTBE A report by a Federal ‘Blue Ribbon Panel on Oxygenates in Gasoline’ which took six months to complete has concluded that there should be a substantial reduction in the use of MTBE as a fuel additive.The panel was appointed by the US EPA in November 1998. Although air quality has been improved by the use of MTBE, it has led to polluted water supplies through leakages from underground storage tanks. In the 1990 Clean Air Act, a 2% oxygen content by weight is required in reformulated gasoline. This legislation would have to be repealed before use of MTBE could be reduced.MTBE consumption in the US is around 300,000 bbl/day, with most of this being in California and the north east. MTBE is added as an oxygenate to more than 85% of reformulated gasoline. Oxygenates must be used to reduce vehicle emissions in cities failing to meet clean air standards. Ethanol is used in around 8% of reformulated gasoline. The use of MTBE has already been banned in Maine and by the end of 2002 it is to be phased out in California.For more information on the Blue Ribbon Panel report see the article on page G142 of this issue of Green Chemistry. Thermal polyaspartate enhances pesticide activity Speaking at the 3rd Annual Green Chemistry and Engineering Conference in Washington DC, USA, at the end of June, Ramon Georgis of the Donlar Corporation of Bedford Park, IL, USA (the first recipient of the Presidential Green Chemistry Award) reported that polyaspartic acid prepared by the thermal polymerisation of aspartic acid (thermal polyaspartate) can enhance the effectiveness of herbicides and insecticides, affording kills at lower concentrations of active ingredient.In combination with polyaspartate, kill effectiveness was enhanced by up to 3 times for several classes of herbicides in the control of broadleaf weeds, while experiments with red fire ants and tobacco budworm demonstrated that kill effectiveness was enhanced by up to 4 times with certain organophosphate and carbamate insecticides.Website: http://www.donlar.com Raw macadamia nut shells being placed in a special oven where they will be carbonised and activated at temperatures above 800 °C.USDA-ARS photo by Scott Bauer Scanning electron micrograph showing the effect activation has on the gross structure of nut shell carbon granules. While it is impossible to see active micro- and meso-pores, the large pits are significant evidence of gasification. USDA-ARS photo by Chris Toles.N E W S G120 Green Chemistry October 1999 This journal is © The Royal Society of Chemistry, 1999 C G Spherilene polyethylene technology Montell is pleased to announce that another Spherilene process polyethylene plant has successfully started up.The 260,000 tonnes/y plant, which is also the world’s largest Spherilene process plant to date, is operated by OPP Petroquimica in Brazil under license from Montell. Montell’s polyethylene gas-phase reactor ‘swing’ technology is capable of producing a wide range of resin types from conventional High Density Polyethylene (HDPE) and Linear Low Density Polyethylene (LLDPE) grades to high-value specialities, including the recently developed HP Quattropolymer grades.Spherilene process plants are designed for minimal environmental impact, avoiding emissions by recycling through the process itself or recovery in the nearby steam-cracker. The Spherilene technology also facilitates smooth startups and re-starts after shutdowns.Montell is a global leader in the production, marketing and sale of polyolefins, advanced materials and related products and is the world’s largest producer of polypropylene. Montell is also the recognised leader in the development of polypropylene catalysts and process technologies.Website: http://www.montell.com Ultrapure water Ion exchange resins remain the dominant method to achieve ultrapure water, but membrane-based continuous (electric) deionisation (CEDI) is emerging as a powerful alternative technology. The power generation industry is the largest consumer of ultrapure water and, in terms of the volume of ultrapure water produced and used, industrial boiler applications dwarf the electronics industry.But the electronics industry is where the growth is, and is where innovation in water treatment technologies is taking place. The electronics sector of the ultrapure water market is expected to take an upturn in 1999 as semiconductor manufacturers invest again in new facilities and plant expansions.CEDI is an attractive clean option because it uses electricity and not chemicals to regenerate ultrapure water and its other advantages include quick and easy installation and continuous operation. But CEDI still requires reverse osmosis pre-treatment and sometimes even an ion exchange resin polishing stage. Nevertheless the growing number of companies moving into CEDI technology suggests that this may well become the dominant technology. In response suppliers of ion exchange resins are innovating to improve resin regeneration efficiency and reducing operating costs to compete.One approach is the development of uniform particle resins which take advantage of advanced production technology to produce specific particle sizes for cations and ions in resins used in ion exchange resin systems.Gas-to-liquid technology ...the Lubrizol Corp., a Cleveland, Ohio, speciality chemical company, together with Syntroleum Corp., a Tulsa, Oklahoma, energy technology company, on 3 Aug 1999 announced an agreement to develop and test additives for use in clean fuels manufactured using Syntroleum’s proprietary gas-to-liquids (GTL) process.Under the agreement, initial programmes will focus on the development of additives to enhance the performance of the ‘designer fuels’ being developed under Syntroleum’s previously announced programme with DaimlerChrysler. Websites: http://www.lubrizol.com and http://www.syntroleum.com. ...ARCO and Syntroleum Corp. have announced the completion and the successful start-up of their Natural Gas-to-Liquids pilot plant.Located at ARCO’s Cherry Point refinery near Bellingham, Washington, USA, the 70 bbl/day pilot plant has achieved initial operating targets and is proceeding with the evaluation programme. The pilot plant is testing new reactor designs and high-performance Fischer–Tropsch catalysts for the Syntroleum Process, a proprietary process for converting natural gas into synthetic fuels and hydrocarbonbased speciality chemicals.Website: http://www.arco.com ...Early Entrance Co Production Plant (EECP) Rentech Inc. of Denver, Colorado, will be part of a project team of companies, led by Texaco, that have been selected by the US Department of Energy (DOE) to develop the engineering design for a new type of energy facility called: ‘the Early Entrance Co Production Plant’ (EECP).The design will combine Texaco’s gasification technology with Rentech’s Fisher–Tropsch technology to provide high quality transportation fuels and electricity from coal and petroleum coke. The DOE will contribute $8 to $8.7 M to the 3 to 5 year project with a total cost of $14.4 M. Website: http://www.gastoliquids.com ...Induction-Coupled Plasma Reforming Process Rentech Inc.of Denver, Colorado, on 3 August 1999 announced that Thermal Conversion Corp. of Kent, Washington, had successfully demonstrated the use of its Induction-Coupled Plasma (ICP) Reforming Process for the controlled production of synthesis gas from natural gas at its 1 MW pilot scale test facility in Kent. Synthesis gas, or syngas (a mixture of hydrogen and carbon monoxide), is the feedstock for the production of clean liquid fuels via the Fischer–Tropsch process.Website: http://www.gastoliquids.com With support from Bayer and BASF, Georg Pohnert and his colleagues at the Max Planck Institute in Jena, Germany, have devised a short stereoselective route to the specific component (17-hydroxylinolenoyl)- L-glutamine (commonly called volicitin) (Chemical Natural defence compound synthesised Communications, 1999, 1087).Volicitin is the component in beet armyworm caterpillar saliva which triggers plants attacked to give off a cocktail of terpenoids attracting parasitic wasps that kill the caterpillars (Chemistry in Britain, August 1997, 15).Green Chemistry October 1999 G121 This journal is © The Royal Society of Chemistry, 1999 N E W S C G Stannic oxide sol provides excellent antistatic efficacy EPS-6 is a new amorphous stannic oxide solution developed by Yamanaka Chemical for the production of coating films that provide a semi-permanent anti-static layer.The new material is environmentally friendly because it does not require the use of a doping agent and it is water-based.Plastic films, electronic materials and various moulded products are all suitable applications for EPS-6. New technology for the prevention of crystallisation of stannic oxide during production has also been developed by the company. Enzymic production of L-aspartic acid By 2000, a new 2000–3000 tonnes/y facility for production of L-aspartic acid is planned to be brought onstream by Nippon Shokubai, using its own novel technology.Global demand for L-aspartic acid is estimated at 10,000 tonnes/y, with the major end-use being artificial sweeteners. Potential new applications include biodegradable materials, including chelating agents, polyaspartic acid and water absorbent resin. These areas are to be expanded by the company.Genetically modified E. coli is used to produce an enzymatic catalyst for use in the new process. No sulfuric acid is used in the process, thus making it more environmentally friendly. Website: http://www.shokubai.co.jp Clean fuels ...the potential of dimethyl ether (DME) as an alternative fuel is being assessed in several countries. For example, the Indian Institute of Petroleum, Gas Authority of India Ltd.and Indian Oil Corp. have signed a Memorandum of Understanding with BP Amoco of the US for the development of DME as a clean alternative transport and power plant fuel in India, while the Shaanxi New Fuels & Burning Equipment Co. of China and Jiuyun International Resources Co. of the US are to jointly develop a project to make super-clean dimethyl ether fuel from coal....BP announced recently its plans to introduce a range of cleaner fuels for motorists in the Paris region, which will lead to significant reductions of automobile and road transport emissions. The range includes a new Ultra Low Sulfur Diesel (ULSD), launched in Paris in September 1999; it will reduce sulfur emission by 90% on all diesel vehicles, without any detrimental impact on performance and will be offered at no extra cost to motorists.ULSD also reduces other emissions substantially and enables new particulate reduction technology to be fitted on buses and other transport vehicles. BP will be the first oil company in France to offer en masse the new diesel which already anticipates the 2005 EU sulfur specifications.Website: http://www.bpamoco.com. ...US companies Johnson Matthey and Clean Diesel Technologies have agreed to do joint research into platinum-based catalysts, with the aim of developing diesel fuel additives able to increase the performances of the particle filters of diesel motors, in order to reduce the emission of particles into the atmosphere. Website: http://www.matthey.com. ...on 22 July 1999 BP Amoco designated Atlanta as its first ‘Clean City’ in the US by introducing new, 30 ppm lower sulfur premium gasolines at both BP and Amoco service stations in the greater Atlanta metropolitan area. Earlier in 1999, BP Amoco announced its Clean Cities programme, in which it will voluntarily bring cleaner fuels to 40 cities around the world by the end of the year 2000.BP and Amoco service stations in the 25-county Atlanta area are now offering new, lower sulfur premium gasoline year round. Since April 1999, BP Amoco has made cleaner fuels announcements in London, Paris and Istanbul. Website: http://www.bpamoco.com Inorganic ‘glass paint’ ThermaCell Technologies Inc. has filed for a patent covering a new kind of environmentally friendly paint that uses inorganic glass to replace organic resins, creating a longer lasting finish for the same price as regular paint.Because it does not contain any volatile organic compounds, ThermaCell’s ‘glass paint’ meets the new, highly restrictive regulations regarding the elimination of environmentally harmful paint ingredients in states like California. Inorganic Hybrid Silicate is the technical name for the product.The company plans to use its ‘glass paint’ to aggressively expand into California, one of the largest paint and coatings markets in the US. The company plans to launch a licensing programme to enable other manufacturers to market their own brands of ‘glass paint.’ Inorganic Hybrid Silicate is resistant to weathering, ultraviolet rays, acid rain, fading, solvents, water, and mildew.It does not chalk, has no odor, does not create harmful vapour barriers; contains no solvents, organic binders, biocides, or mildewcides; and is available in clear and pigmented. ThermaCell Technologies Inc. is a technologically enhanced manufacturer and marketer of paints, coatings and building materials. The company manufactures conventional paints, coatings and building materials through traditional trade and retail venues.The company also manufactures VaxCell microspheres, which provide greater insulation, protection, strength, longevity and value in paints, coatings and building materials. Website: http://www.thermacell.com Biochemie to quadruple 7-ACA capacity Biochemie is to build a new production plant for 7-aminocephalosporanic acid (7-ACA) in Frankfurt at a cost of DM 85 M ($45 M).It will use an enzyme catalytic process and will have a capacity of over 400 tonnes/y. Startup is due in 2000. The company, which is the antibiotics subsidiary of Novartis, already has a 100 tonnes/y 7-ACA plant at the site which uses the same process. It bought the site from Hoechst in 1998.The new unit will take its total 7-ACA output to 700–800 tonnes/y, making it the world’s leading producer. 7-ACA is an important antibiotic intermediate. The enzyme process is cheaper and cleaner than conventional production methods. Synetix wins environmental award Synetix, ICI’s recently established business, has been awarded the Queen’s Award for Environmental Achievement for Hydecat, a process that treats sodium hypochlorite produced from waste chlorine streams.Effluent is passed through the catalyst bed using gravitational feed and has no moving parts of pumps. Sodium hypochlorite (bleach) is converted by the process from a potentially harmful mixture to a benign common salt solution and oxygen. Over20 companies in 9 countries have successfully applied the Hydecat technology, with cost savings.Website: http://www.synetix.com Environmentally friendly credit cards Visa International, one of the world’s largest credit card companies, has recommended that credit cards can now be produced with a more environmentally friendly material, glycol-modified PET (PETg), as a substitute for PVC. Visa issued over 580 M cards worldwide in 1998.Manufactured by Eastman Chemical in the US, 75% of PETg’s sales are in Europe and there is growing demand in Japan and the US. Website: http://www.visa.com Fuel cells DaimlerChrysler DaimlerChrysler (DC) is leading the race to market fuel cell cars, and is developing methanol as its preferred fuel. DC’s experimental car, the Necar 3, is based on the A-Class Mercedes which has its engine under the body of the car, but the power unit is in the rear.It is claimed that the Necar 3 has a range of 400 km on the 40-litre tank of methanol fitted to the car. Hydrogen is the simplest fuel for fuel cells but its storage is difficult, and hence the interest in methanol. The American Methanol Institute estimates that 2 M methanol fuel cell vehicles in 2010 will require 2.64 M tonnes methanol and in 2020 35 M vehicles would need 46 M tonnes together with a capacity increase of 35% to produce it.Websites: http://www3.daimlerchrysler.com/ and http://methanol.org/fuelcell/ Ford On 16 August 1999 The Ford Motor Co. opened the first filling station in North America that can refuel vehicles with either liquid or gaseous hydrogen. It is the second such filling station in the world and bolsters Ford’s commitment to clean hydrogen vehicles.Ford intends to be the leader in the production of fuel cell vehicles. This refuelling station, right on the site of the North American Research and Engineering campus, gives Ford an edge by allowing them to easily refuel and conduct tests on the company’s vehicles and in the labs.The station officially opened with the refuelling of Ford’s P2000 HFC (hydrogen fuel cell) sedan, which is powered by gaseous hydrogen. The station will help Ford researchers analyze the benefits of liquid vs. gaseous hydrogen refuelling, different types of nozzles for refuelling and different pressures for optimal refuelling with hydrogen. While primarily used for fuel cell development, Ford also is conducting significant research on hydrogen powered internal combustion engines.Website: http://www.ford.com New refrigerant as CFC replacement Solpower Corp. has announced projected benefits resulting from chlorofluorocarbon (CFC) global banning initiatives. Europe, Canada and Japan have recently introduced more effective usage bans on CFCs that have significantly increased the market opportunities for Solpower Corp’s SP34E, a direct drop-in replacement gas for R12 and R134A refrigerants.SP34E has captured almost 15% of the Australian refrigeration market in less than a year. Solpower Corp. reports that its refrigerant gas SP34E is the solution to the Montreal Protocol initiatives for implementation of CFC bans. In addition to being a direct drop-in replacement for R12 and R134A, Solpower’s SP34E also will not damage the ozone layer, requires minor system modification, requires no special system handling equipment, is compatible with mineral oils and PAG/POE oils, outperforms both R12 and R134A in most cases and is more efficient than R134A with more capacity and lower head pressures.Website: http://www.solpower.com Biomass ethanol plant Many in the USA are convinced that ethanol from biomass is the fuel for the future, especially with the proposed phaseout of MTBE.For example, Massachusetts-based BC International Corp. are planning to construct a ‘biorefinery’ next year south of Oroville in California. It will convert about 75,000 tons of rice straw, 125,000 tons of orchard N E W S C G G122 Green Chemistry October 1999 This journal is © The Royal Society of Chemistry, 1999 Please note, in relation to the News item on page G91 of the last issue of Green Chemistry (August 1999), that the Zevco Emission Vehicle Company Ltd.no longer have any involvement with the fuel cell-powered Millennium Taxi. slash and 40,000 tons of other agricultural waste into 22 million gallons of ethanol each year.BC International already have a similar plant in operation in Jennings, Louisiana. Adhesives for US postage stamps The USA’s first self-adhesive postage stamp was issued by the US Postal Service (USPS) in 1974. Self-adhesive stamps were reissued in 1987 and sales have grown rapidly to reach a projected 93% of stamps sold in 1999. Their use is adversely affecting the efficient recycling of paper, however, since the pressuresensitive adhesive (PSA) on the stamp breaks down in the repulping process to clog equipment and to appear as dirt or imperfections in the recycled paper.The USPS contracted Specialized Technology Resources Inc. in 1995 to develop environmentally benign PSAs and Franklin International and Spinnaker were also employed.A new PSA, Covinax 2000, has been developed and is currently under extended testing. Website: http://www.duracet.com Catalysts ...Low-temperature hydrogenation French chemists have developed a highly efficient catalyst system for hydrogenating aromatic compounds to make cleaner diesel fuels. The fully recyclable catalyst operates at room temperature and atmospheric pressure.ENSC de Rennes has developed a new liquid–liquid system based on rhodium metal particles just a few nanometres in diameter suspended in water to form a colloid. The second phase is the aromatic reactant and its products, and therefore no solvent is needed. The system efficiently hydrogenates benzene and its derivatives to their cyclohexane equivalents. This system appears to be the most efficient for converting benzene to cyclohexane, and toluene, cumene, anisole and phenol to their hydrogenated forms in very mild conditions. Website: http://ensc-rennes.fr ...a computer programme which can assist in the production of catalysts has been announced by Dewi Lewis of University College London.He developed the programme alongside David Willock of the University of Wales, using patterns found in nature toC G Green Chemistry October 1999 G123 This journal is © The Royal Society of Chemistry, 1999 N E W S Rome’s city fathers are paying to clean the faces of nearly 7000 buildings as the eternal city prepares to celebrate the new millennium in style.Hydro Facade, a cleaning compound made from pure calcium carbonate, will be used to clean and polish some very important buildings in Rome.The list includes Italy’s national assembly, known as Montecitorio, the government building Palazzo Chigi, and Villa Farnesina, The colonnade at St.Peter’s in Rome is being cleaned with Hydro Facade. Hydro Facade cleaning up Rome which houses the country’s foreign affairs department. The Hydro product will also be used to clean the colonnade at St.Peter’s. In Rome, Hydro Chemicals works together with a local company, Agep Srl. The companies have carried out a large number of jobs over the past three years, not only in cleaning the surfaces of major buildings, but in removing graffiti from subways and trains. Website: http://www.hydro.com invent improved types of catalyst which can speed up chemical reactions.Called Zebedde (zeolites by evolutionary de novo design), the compter program, which duplicates the biased randomness found in evolution, selects molecular fragments from a library to be used in a catalyst.A series of potential combinations is produced, which a researcher then selects from, based on an understanding of chemical properties. Zebedde has the potential to speed up and simplify the use of catalysts in synthesising lead substitutes for petrol or for producing gasoline. ...Magic catalysts.In a recent issue of Chemistry in Britain (August 1999, 35(8), 25–27) there was an article on the development of catalysts using tungsten and molybdenum, in consequence of shrinking reserves of platinum and other Group VIII transition metals.The article describes the work by Malcolm Green’s laboratory in the Wolfson Catalysis Centre at the University of Oxford (http://www.chem.ox.ac.uk/icl/ catcentre/carbides.jpg), Marc Ledoux’s group at the Université Louis Pasteur in Strasbourg and others in the application of molybdenum and tungsten carbides to a range of industrial and environmental reactions. Examples of the use of the carbides include Fischer–Tropsch synthesis of hydrocarbons, benzene hydrogenation, hydrodesulfurisation of thiophenes and isomerisation of hexane, heptane and octane.Examples of the use of the nitrides include ammonia synthesis from its elements and hydrodenitrogenation. Biodegradable plastic from GM plants The biotechnology giant Monsanto claims to have created genetically modified (GM) plants that can ‘grow plastic’.The plants, principally oilseed rape, contain four added genes from bacteria that naturally produce a biodegradable plastic called PHBV, according to a recent article in Nature Biotechnology. Biodegradable plastics have been produced before using bacteria alone but the process has been too expensive and the end-product has been too brittle for most applications.The new GM process produces a biodegradable product which is suitable for commercial use. Ken Gruys, who leads this research at Monsanto, says that this a really only a first step since the current yield of plastic is only 3%. He says that the next step is to refine the GM process to make it suitable for high-yield production; this may take up to 10 years.Metallocene catalysts According to Univation Technologies, the global market for metallocene catalysed polyethylene (PE) will grow at a rate of 45% per year up to 2010. The regions experiencing greatest growth are forecast to be North America, Asia and Western Europe. Univation Technologies is a licensing joint venture established by Union Carbide and Exxon Chemical to sell Unipol technology. Competing technology is supplied by Dow Chemical/BP Chemical by their Insite/Innovene technologies. The technology has been installed in PT Peni’s PE plant in Indonesia, which is producing commercial quantities of product. The key to metallocene catalysis growth will be consistent production of LLDPE using the technology, according to the Catalyst Group, consultants based in Houston, Texas. The market leaders in metallocene catalysis are Exxon and Dow. New research is being carried out into styrene/ethylene interpolymers (Index) by Dow. Another company using metallocene technology is Phillips Petroleum at Bartlesville, Oklahoma, which produces PE which it sells under the mPACT brand name. Ethane-to-ethylene A novel approach to the production of ethylene is being developed by a team from the University of Minnesota and the Polytechnic University in Milan. They flow a mixture of ethane, hydrogen and oxygen over a catalyst made by depositing platinum and tin on alumina. The gaseous mixture would be expected to explode, but apparently the presence of the ethane prevents this. The hydrogen in the product balances that needed in the feed. Conversions of 60% with a selectivity of 85% have been achieved. The mechanism of the reaction is obscure.

ISSN:1463-9262    

DOI:10.1039/a908572f

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

C G More 1999 Presidential Green Chemistry Awards Paul Anastas Mary Kirchchoff and Tracy Williamson of the US EPA present the second in a series of short profiles on Plant at South Glen Falls NY in which levulinic acid is produced from cellulosic biomass. 19 9 9 G R E E N C H E M I S T R Y AWA R D S and agricultural residues. Levulinic acid serves as a building block in the synthesis of useful chemical products. Markets already exist for tetrahydrofuran succinic acid and diphenolic acid all of which are levulinic acid derivatives. The use of diphenolic acid (DPA) as a monomer for polycarbonates and epoxy resins is currently under investigation. An industry/government consortium has conducted research on two additional derivatives with commercial value methyltetrahydrofuran (MTHF) a fuel additive and d-amino levulinic acid (DALA) a pesticide.The conversion of levulinic acid to MTHF is accomplished at elevated temperature and pressure using a catalytic hydrogenation process. MTHF is a fuel additive that is miscible with gasoline and hydrophobic allowing it to be blended at the refinery rather than later in the distribution process. Using MTHF as a fuel additive increases the oxygenate level in gasoline without adversely affecting engine performance. MTHF also boasts a high octane rating (87) and a low vapor pressure thereby reducing fuel evaporation and improving air quality. MTHF represents the first practical example of the direct incorporation of hydrogen in liquid fuels.DALA can be obtained from levulinic acid in high yield using a three-step process. DALA is a broad-spectrum pesticide that is non-toxic and biodegradable. Its activity is triggered by light selectively killing weeds while leaving most major crops unaffected. DALA this year’s Presidential Green Chemistry Awards. To Biofine1 for their economic conversion of cellulosic biomass to chemicals Replacing petroleum-based feedstocks with renewable ones is a crucial step toward achieving sustainability. When considering alternatives to traditional feedstocks attention often focuses on plant-based materials. Renewable biomass conserves our dwindling supplies of fossil fuels and contributes no net CO2 to the atmosphere.Biofine has developed a high-temperature dilute-acid hydrolysis process that converts cellulosic biomass to levulinic acid (LA) and derivatives. Cellulose is initially converted to soluble sugars which are then transformed to levulinic acid. By-products in the process include furfural formic acid and condensed tar all of which have commercial value as commodities or fuel. Feedstocks used include paper mill sludge municipal solid waste unrecyclable waste paper waste wood The Biofine process 1 Biofine is a ‘virtual’ company formed for the purpose of owning the levulinic acid process patents and other related intellectual property. BioMetics Inc. is a (bio)chemical engineering consultancy and engineering company which designed built and operated the Biofine large-scale demonstration plant at South Glen Falls New York.G124 Green Chemistry October 1999 This journal is © The Royal Society of Chemistry 1999 also shows potential as an insecticide. Diphenolic acid is synthesized by reacting levulinic acid with phenol. DPA has the potential to displace bisphenol-A a possible endocrine disruptor in polymer applications. Brominated DPA shows promise as an environmentally-acceptable marine coating while dibrominated DPA may find use as a fire retardant. Currently levulinic acid has a worldwide market of about one million pounds per year at a price of $4–6/lb. Large-scale commercialization of the Biofine process could produce levulinic acid for as little as $0.32/lb spurring increased demand for LA and its derivatives.Using the Biofine process waste biomass can be transformed into valuable chemical products. The ability to produce levulinic acid economically from waste biomass and renewable feedstocks is key to increased commercialization of LA and its derivatives. For more information on the Biofine process contact Dr. Steve Fitzpatrick on sfitzp@biometicsma.com To Nalco Chemical Company for ULTIMER®—the first of a new family of water soluble polymer dispersions High molecular weight polyacrylamides are commonly used as process aids and water treatment agents in various industrial and municipal operations. Annually at least 200 million pounds of water soluble acrylamide-based polymers are used to condition and purify water.These water soluble polymers assist in removing suspended solids and contaminants and effecting separations. Traditionally these polymers are produced as water-in-oil emulsions. Emulsions are prepared by combining the monomer water and a hydrocarbon oil/surfactant mixture in approximately equal parts. Although the oil and surfactant are required for processing they do not contribute to the performance of the polymer. Consequently approximately 90 million pounds of oil and surfactant are released to the environment each year. Nalco has developed a new technology that permits production of the polymers as stable colloids in water eliminating the introduction of oil and surfactants into the environment.The Nalco process uses a homogeneous dispersion polymerization technique. The water soluble monomers are dissolved in an aqueous salt solution of ammonium sulfate then polymerized using a water soluble free radical initiator. A low-molecular-weight dispersant ULTIMER® polymers are totally water-based. Therefore activation for use is as simple as diluting the product prior to feeding. 19 9 9 G R E E N C H EMI S T R Y AWA R D S polymer is added to prevent aggregation of the growing polymer chains. For end use applications the dispersion is simply added to water thereby diluting the salt and allowing the polymer to dissolve into a clear homogeneous polymer solution. This technology has been successfully demonstrated with cationic copolymers of acrylamide anionic copolymers of acrylamide and non-ionic polymers.Development of water based dispersion polymers provides three important environmental benefits. First the new process eliminates the use of hydrocarbon solvents and surfactants required in the manufacture of emulsion polymers. Dispersion polymers produce no VOCs and exhibit lower biological oxygen demand (BOD) and chemical oxygen demand (COD) than emulsion polymers. Second the salt used ammonium sulfate is a waste by-product from another industrial process the production of caprolactam. Caprolactam is the precursor in the manufacture of nylon; 2.5—4.5 tons of ammonium sulfate are produced for every ton of caprolactam providing a ready supply of feedstock.Finally dispersion polymers eliminate the need for costly equipment and inverter surfactants needed for mixing emulsion polymers. This technological advantage will make waste water treatment more affordable for small- and medium-sized operations. Nalco’s dispersion polymers contain the same active polymer component as traditional emulsion polymers without employing oil and surfactant carrier systems. The polymers are produced as stable colloids in water retaining ease and safety of handling while eliminating the release of oil and surfactants into the environment. By adopting this new technology Nalco has conserved over C G one million pounds of hydrocarbon solvent and surfactants since 1997 on two polymers alone. In 1998 the water based dispersions utilized 3.2 million pounds of ammonium sulfate a by-product from caprolactam synthesis that would otherwise be treated as waste. Additional environmental benefits will be realized as the dispersion polymerization process is extended to the manufacture of other polymers. For more information on Nalco Chemical Company and ULTIMER® polymers see the web site http://www.nalco.com Green Chemistry October 1999 G125 This journal is © The Royal Society of Chemistry 1999

ISSN:1463-9262    

DOI:10.1039/a908573d

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

G126 Green Chemistry October 1999 This journal is © The Royal Society of Chemistry, 1999 C G F EAT U R E residues from the manufacturing stage. That focus has since been broadened considerably to include energy, water, and natural resources, and to recognize that a product’s environmental impacts during manufacture may not be the most important. Indeed, sometimes (as with the automobile) the impacts at life stages other than manufacturing are dominant.The product designer has many opportunities to influence resource flows and associated environmental impacts. In the conceptual tool generally employed as part of an industrial ecology design activity, termed Design for Environment (DFE), environmental considerations are added to other design considerations ndustrial ecology, like green chemistry, is less than a decade old.Nonetheless, its importance has become widely recognized, as has its perspective—to view the entire modern technological system, and the products of that system, much as biological ecologists view natural ecosystems and individual organisms.1 In systems of both types, flows of resources and energy are studied in order to assess the use of materials and energy, sources of loss, loss mechanisms and techniques for amelioration.Industrial and biological ecology analyses can be performed on scales as large as that on the entire global society or natural system, or as small as a single product, creature or physical process. A characteristic that distinguishes industrial ecology from many other environmentally related topics is its breadth in space and time.In the case of a product, for example, it looks not just at the manufacturing stage, but at all life stages—from birth to death or, ideally, from birth to reincarnation. Such breadth has not typically been a characteristic thus far of green chemistry approaches, which focus on minimizing or avoiding residues of all kinds, especially hazardous ones, arising from the manufacturing process.2 This approach is laudable but unnecessarily narrow, failing to capture many environmental aspects of chemical manufacture, use and disposition.Hence, it is appropriate to expand the concept of green chemistry so as to place its approach squarely within the industrial ecology context. As shown below, adding a life-cycle perspective to green chemistry enlarges its scope and enhances its environmental benefits.The product life cycle The concept of life-cycle assessment (LCA) was originally developed to aid in assessing the environmentally related attributes of manufactured products. It considers five life stages: Premanufacture, Manufacture, Product delivery, Product use and End of life.3 The stages are characterized in part by the ways in which resources are used.Energy is consumed at each stage, process chemicals or consumables in most, and water in some. Each stage has the potential to generate residues. When the product becomes obsolete, it may have the potential to be refurbished, remanufactured or recycled. It is worth noting that this approach has evolved from that of a decade or two ago, when the sole interest of manufacturers, government regulators, and other interested parties was on ‘adding a life-cycle perspective to green chemistry enlarges its scope and enhances its environmental benefits’ Green chemistry in an industrial ecology context Thomas Graedel discusses extending green chemistry from merely green synthesis to greening of entire life cycles I Thomas E.Graedel is Professor of Industrial Ecology in the School of Forestry and Environmental Studies, Yale University, a position he assumed in 1997 after 27 years at AT&T Bell Laboratories. He was the first atmospheric chemist to study the atmospheric reactions of sulfur and the concentration trends in methane and carbon monoxide. One of the founders of the newly emerging field of industrial ecology, he co-authored the first textbook in that specialty and has lectured widely on its implementation and implications.His matrix assessment tool, developed while at AT&T, is a widely-used standard for the environmental assessment of products and services.C G Green Chemistry October 1999 G127 This journal is © The Royal Society of Chemistry, 1999 F EAT U R E (safety, performance, cost, etc.). The ideal result is a product that is environmentally superior while it simultaneously meets or exceeds its other design targets.How might such a life-cycle concept be applied to chemical products? Consider any firm that buys a chemical from a supplier and manufactures a final product, especially a product that may eventually be recycled.Examples include a company that purchases ABS (acrylonitrile–butadiene–styrene) thermoplastic resin and uses injection molding to form it into desk telephones, or a company that buys cyanides to plate one metal on another. In either case, the life stage sequence is shown in Figure 1. Figure 3. The life cycle of a chemical intermediate (possible reuse routes are omitted for clarity).* The designer of the product that uses ABS or nickel plating clearly influences the environmental aspects of more than the manufacturing stage; in actuality, she or he has the potential to affect all life stages implicitly or explicitly, for good or ill.An environmentally sensitive chemical product designer can, for example, optimize supplier manufacturing processes, determine the use of consumables while the product is in service, and help to define eventual product recyclability.A common variation on this theme is for the chemical product to be one that is dissipated in use, such as a pharmaceutical preparation, a hair spray, or a herbicide. The life stage sequence in this case is shown in Figure 2. In this case, the manufacturer directly controls all life stages but Premanufacture, and can influence that stage through its interactions with suppliers.Products designed to be dissipated in use have, of course, no End of life stage and thus no prospect for recycling. Nevertheless, the life cycle approach, as modified, retains its ability to focus attention to the use of resources other than raw materials, as well as to consider the environmental implications of the product or its constituents prior to the manufacturing stage, during packaging and shipping, and during product use.Finally, consider the manufacture not of a final product, or a chemical product designed to be dissipated in use, but of a chemical intermediate such as ABS resin. The customer for that product views the life cycle from the perspective of Figure 1, where both the resin manufacture and those steps that produced the ABS feedstocks are in the Pre-manufacturing life stage.From the perspective of the ABS resin manufacturer, however, only the feedstock processing is Premanufacture, and the Manufacture and Product Delivery life stages must be considered twice, once for manufacture of the chemical intermediate, once for the final product (Figure 3).At first glance, the chemical company that manufactures the resin might be thought to influence only life stages 2a, 3a, and perhaps 1. In fact, the resin designer directly influences stages 2b and 5 as well, because the type and concentration of fillers, plasticizers, flame retardants, and other additives define much of the final product processing and potential recyclability.A green chemistry life-cycle approach thus involves not only in-plant actions, but also working with the final product Figure 1. The life cycle of a recyclable chemical product.* Figure 2. The life cycle of a dissipative chemical product.* * On these diagrams, the double-lined box indicates the life stage within which the principal activity of the designer’s corporation resides.A circled E indicates energy input, a circled C the input of process chemicals or consumables, a circled R the generation of residues. Reuse of the product or its components or materials is an option in the last life stage. The dashed lines indicate resource or residue flows that can potentially be directly influenced by the product designer.The dotted lines indicate flows that may be influenced as a result of negotiations with suppliers.F E AT U R E C G G128 Green Chemistry October 1999 This journal is © The Royal Society of Chemistry, 1999 manufacturer in a joint effort to improve environmental performance. Industrial ecology goals for green chemists To build on the already substantial green chemistry accomplishments described in this journal and elsewhere, green chemists should place their activities within an industrial ecology context.4 Many of the guidelines and tools developed for the evaluation of assembled products and of industrial processes can be adapted for use in green chemistry as supplements to the manufacturing-oriented guidelines that already exist.3 In this connection, a few goals that merge green chemistry and industrial ecology are as follows: l Adopt a life-cycle perspective regarding chemical products and processes l Realize that the environmentally-related activities of your suppliers and your customers determine, in part, the greenness of your product l In the case of non-dissipative products, consider recyclability as well as manufacture l In the case of dissipative products, consider the environmental aspects of product delivery and use as well as manufacture l Perform green process design as well as green product design How might directing efforts toward these goals redefine the practice of green chemistry? A first demonstration of that redefinition is that consideration of the earliest life stage will lead naturally to the use of sustainable feedstocks.5 A second is that consideration of potential environmental impacts in product delivery and customer use will lead to such innovations as reusable containers for liquid chemicals, as well as agreements to lease, recover, purify, and reuse processing chemicals.A third is that considerations of the End of life stage will encourage product formulations that avoid non-recyclable additives or coatings.6 A particularly commendable example of the latter is a photosensitive epoxy covercoat recently developed by IBM scientists; it is very rugged during normal service, but can readily be stripped away photochemically to enable recovery of the underlying electronic components and materials.7 Green chemistry has accomplished much with its emphasis on decreased toxics, diminished byproduct flows, solvent substitutions, and other activities within the factory walls.It is now time to look beyond these walls and recognize that green chemistry is more than green synthesis. It is the minimization of the environmental impacts of not only an industrially utilized molecule, but also of its feedstocks and its products. As green chemists green the activities within their facilities, they should also green entire life cycles, because that is how the environmental benefits will be greatest. References 1. R. A. Frosch (1995) Sci. Am, 273(3), 144-147. 2. P. T. Anastas and J. C. Warner (1998) Green Chemistry: Theory and Practice, Oxford, UK: Oxford University Press, 135 pp. 3. T. E. Graedel (1998) Streamlined Life-Cycle Assessment. Upper Saddle River, N.J.: Prentice Hall, 310 pp. 4. R. Breslow (1996) Chem. Eng. News, p. 72, Aug. 26. 5. C. Okkerse and H. van Bekkum (1999) Green Chemistry, 1, 107–114. 6. American Plastics Council (1996) Designing for the Environment: A Design Guide for Information and Technology Equipment, 38 pp., Washington, DC. 7. S. L. Buchwalter and L. L. Kosbar (1996) J. Polym. Sci. Polym. Chem. 34, 249–260. ‘entire life cycles need to be greened’ ‘green chemistry is more than green synthesis’

ISSN:1463-9262    

DOI:10.1039/a908574b

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

Green Chemistry October 1999 G129 This journal is © The Royal Society of Chemistry, 1999 Nottingham, combining the Nottingham group’s expertise in supercritical fluid technology with the polymer expertise at Surrey. Through an EPSRC (Engineering & Physical Sciences Research Council) grant the teams started to look at polymerisation of acrylate systems. In terms of its solvent power scCO2 has many similarities to fluorocarbons—being a good solvent for siloxanes and fluoropolymers but a non-solvent for both hydrophilic and lipophilic polymers. One of the problems with polymerisation of acrylate systems in scCO2 is the difficulty in building up molecular weight due to lack of solubility.The Surrey group has been concentrating on synthesis of dispersion stabilisers, in particular siloxanes, to overcome this problem.The approach has been successful, with a number of stabilisers such as poly(dimethylsiloxane)monomethacrylates proving useful at enabling reasonable molecular weight polymers to be obtained. During the course of this work valuable information on the nature of polymerisation in supercritical fluids was noted by the Nottingham collaborators. For instance wall effects were observed in stirred solutions which were inhibiting polymer growth.Although there is some industrial evidence that metal ions inhibit acrylate polymer growth this is not usually a cause for concern, but owing to the very high diffusion rates in scCO2 it is thought that this factor is now coming into play. The effect is, however, minimal in unstirred reactions. Apart from polymer synthesis John F O C U S O N .. . Focus on— Professor John Hay Hay sees supercritical fluids playing a key role in polymer coatings technology. The setting up of a new Centre for Supercritical Coatings Technologies (S-COAT) has recently been announced. Through his time in industry he realises how vital it is to get both industry and engineers involved at an early stage in the development of new technology.In setting up the new Centre he is working closely with Professor Mojtaba Ghadiri, an expert in particle technology in the University’s School of Engineering in the Environment. The Centre currently has support from EPSRC (e.g. a recent grant worth £240,000) together with money from the Joint Research Equipment Initiative (JREI); industrial partners include Chemical and Polymer, Messer UK and Lafarge Braas.The core technology in use at the centre will be the UniCarbä process, developed by Union Carbide and Nordson, for spray coating substrates from supercritical carbon dioxide. The process uses decompressive atomisation technology to produce droplets, the rapid decompression and evaporation of the two within the coating material producing high internal forces, which overcome surface tension and cohesive forces and produce a highly uniform spray.Professor Hay will be the Centre Manager whilst Chemical and Polymer will carry out marketing activities both for the centre and any technology developed. The Centre’s resources (50%) will be available for hire by industry whilst the remaining time will be used for C G Mike Lancaster of the Green Chemistry Network continues his series on leading Green Chemistry/Clean Technology groups, reporting on the work of John Hay and his colleagues at the University of Surrey in Guildford, UK fter completing his Ph.D.at Edinburgh University, John Hay spent his early career at the BP Amoco Research Centre in Sunbury-on- Thames working in the field of polymer science, especially advanced materials.His association with Surrey began in 1989 when he joined Kobe Steel Europe Ltd., based on the University Research Park. Professor Hay joined the academic staff full time in 1994 as Reader in Organic Chemistry and became Professor of Materials Chemistry in early 1999. Supercritical fluids John Hay's interest in clean technology really started in 1992 when he saw the now classic DeSimone paper in Science on the ‘Synthesis of Fluoropolymers in Supercritical Carbon Dioxide’.Although the 'inert' properties of fluoropolymers have enabled their use in applications such as lubricants for computer disks and sealants for aircraft fuel systems, they have posed problems for their synthesis.They are conventionally made by homogeneous free radical polymerisation but the only suitable solvents have been CFCs —the main cause of damage to the ozone layer. The use of scCO2 improved the 'greenness' of the manufacturing process at a stroke. The search was now on to clean up other polymer syntheses; use of scCO2 offers the possibility of using an inexpensive, recyclable, environmentally sound alternative to organic solvents.Early on Professor Hay began to collaborate with Steve Howdle at AG130 Green Chemistry October 1999 This journal is © The Royal Society of Chemistry, 1999 R&D programmes. Surrey will be the only university outside the US with a licence to use the UniCarbä process. The main focus of the early work will be around developing an understanding of how dispersion coatings are formed from supercritical fluids, techniques used to study behaviour at the spray nozzle including rheology and high-speed photography.By optimising parameters such as temperature, pressure, dispersant and solids loading, the team hopes to be able to gain a detailed knowledge of the underlying science and engineering, which should aid the development of industrially acceptable coatings from dispersion systems.Although not with dispersion polymers, the UniCarbä process is having some commercial success as an environmentally friendly method of spray coating with polymers. Uses include painting of warships at a US Navy base to avoid nearby residents being exposed to solvent vapours and painting of agricultural machinery by the Italian company Salchi.Several car-manufacturing companies are also assessing the technology. Polymer curing Another of John Hay's Clean Technology research areas is in the field of polymer curing. He has recently been awarded an EPSRC grant with chemistry and physics colleagues to work on polymer and composite processing using electron and proton beams; partners in this research include British Aerospace, Akcros and DERA.Electron beam processing uses highenergy electrons to initiate polymerisation and crosslinking in suitable composite matrices. Since the particle beam is operated at low temperature, the technique allows the elimination of most of the drawbacks associated with conventional thermal cure. Advantages of this technique include: l Reduced energy use, estimates suggesting that operating costs will be at least 25% lower than with autoclave curing techniques.l Reduced volatile production, this low temperature technique greatly reduces the formation of volatile degradation products. l Reduced curing times enabling greater throughput. Although details of this work are confidential at present there are high hopes that industrial uses for this technology will be realised.Radioactive waste reduction In association with Professor John R Jones and others at the University, John Hay is looking at ways of reducing the volume of radioactive waste produced as a result of the large number of 14C and 3H samples that are detected using liquid scintillation counting. The Surrey team has been working on an EPSRC / ROPA funded programme in which sol–gel technology plays an important part.The primary solute of the scintillation system can be incorporated in the sol–gel glass, thereby greatly reducing the amount of aromatic solvent, usually toluene, which is normally required. This is done without any loss in the counting efficiency. In a separate venture, Professor Jones is looking at cleaner ways to produce tritium labelled pharmaceuticals.These are being increasingly used to study metabolic pathways but conventional methods are often not very efficient at incorporating the tritium. Professor Jones has found that by using microwave technology the efficiency of the radiolabelling synthesis step can often be significantly improved.Dr Tim Danks is also researching the use of microwaves in high efficiency, solvent-free organic synthesis. The Green Chemistry Movement The University of Surrey is undoubtedly at the forefront of UK universities in terms of teaching Green Chemistry. As an example, John Hay along with Drs Cunningham and Faulkner has introduced a 20-hour lecture course entitled ‘Clean Organic Chemistry’.This final year option course aims to make the student aware of the environmental challenges facing the organic chemicals industry as well as presenting approaches to cleaner and more selective syntheses. Most F O C U S O N . . . C G Advantages of the UniCarbÔ Process Compared to Conventional Coating Processes l Reduced operating and capital costs l Significant reduction in VOC emissions l Reduced worker exposure to organic solvents l Improved coating appearance and performance l Lower maintenance costs aspects of Green Chemistry are covered in the course including: l Alternative solvents l Supported catalysis l Selective asymmetric synthesis l Use of non-thermal energy sources John Hay's time in industry has helped him achieve a good understanding of what industry wants from clean technology and he has had little difficulty in finding industrial partners.He does, however, believe that finding interested parties can be a difficult and time consuming task for academics and there is a definite role to play for an organisation such as the Green Chemistry Network in facilitating the process of technology transfer and introducing potential partners. Workshops on particular technology themes would be an ideal way. Hay believes that the EPSRC clean technology initiative was most valuable in encouraging academics to think about the area. This, coupled with an ever-increasing requirement for industrial partners, should enable a greater and faster uptake by industry. With all new technology a product champion is required to drive it forward, one major problem in the UK at the moment being that industry reorganisation is moving at such a pace that the 'champion' is rarely in the job long enough to be able to see the project through. As a consequence industry often loses interest in a project before completion—there is no real answer to this until industry becomes more stable. The Unicarb Ôprocess uses carbon dioxide to replace organic solvents in spray coating systems.

ISSN:1463-9262    

DOI:10.1039/a908575k

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

s we enter a new millennium we reflect upon the concept of membrane science and technology. This is impossible without making a critical analysis of the state-of-the-art in this field. Our speculations are evoked in part by, and agree to a large extent with, an ideology which is currently in progress, the so-called clean technology, green chemistry, or benign chemistry. Intense scientific and technical progress has resulted in the average life expectancy rising from 47 in 1900 to 75 years in the 1990s.These almost unbelievable achievements have come at a price. The manufacture, use, and disposal of synthetic chemicals have had many negative side-effects on human health and the environment. This is primarily due to the fact that synthetic chemists are at the beginning of the process—designing synthetic pathways to produce a target product at the lowest cost with the higher yield—while the problems have traditionally been identified with the end of the process—the waste stream.Therefore, the comparatively young membrane technology was traditionally considered as a part of separation technologies aimed at solving the present-day problems.In our opinion, such a passive position with today’s membranology does not allow one to completely reveal its potential in realization of chemical and biochemical processes. This potential is evident from the determining role which membranes (especially in combination with catalysis) play in the vital activity of living organisms and plants. The membrane technology of the next generation must, first of all, do no harm.Therefore, a membranologist should switch to a new ideology and start to play an active role in designing novel synthetic methodologies that use renewable rather than depleting feedstocks (fossil fuel), maximize the incorporation of all materials used in the process into the final product, apply catalytic rather than stoichiometric reactions, prevent waste, etc.The active position of a membranologist in the design of chemical and biochemical processes should primarily manifest itself in such conceptual approaches as the membrane reactor, the membrane bioreactor, the catalytic membrane reactor, catalysis in membrane reactor, and membrane contactor. In these systems a chemical reaction and a membrane separation are coupled in one unit operating in a continuous mode.This provides a considerable advantage due to the shift of an equilibrium to the desired side, a decrease in the inhibiting action of the products, or creating a driving force for membrane separation. As for the coming decade, this period should become a turning point in the passage to the new membrane ideology. From the point of view of particular technical problems, we can consider the role of membranes in the processes of more efficient processing of fossil fuels upon transition from depleting to renewable feedstocks.Recently, great attention has been paid to the development of inexpensive and effective technologies that can be used for methane conversion to easily transportable fuel. The creation of membrane reactors, in which air is used as a source of oxygen, is one of the promising directions in this field.An oxygen selective membrane, which can separate oxygen from air and supply oxygen of 100% purity into a reactor, is a key element of such reactors, which are currently under development at various research centers. The concept, which is based on a complex approach to the problems of developing inorganic materials for catalytic membrane reactors, is very attractive.At the first stage, a starting material is used to form a reactor on the whole (reactor shell, membranes, joints, etc.). Then, the necessary separation and catalytic functions are given to the membrane in situ, strongly depending on conditions of a specific oxidation process and hydrocarbon feed.` During the process of conversion to useful organic chemicals, crude oil undergoes oxidation. This oxidation step has historically been one of the most environmentally polluting steps in all heavy organic syntheses. In general, agricultural and biological feedstocks can be used as excellent alternative feedstocks, which are highly oxygenated by nature. Furthermore, syntheses can be accomplished that are significantly less hazardous than those involving petroleum Membrane science in the next decade V.V. Volkov, V. V. Teplyakov, I. S. Kalashnikova, L. Valuev and N. A. Platé from the A. V. Topchiev Institute of Petrochemical Synthesis in Moscow maintain that membranes will make an increasing contribution to many areas of clean technology including the exploitation of renewable feedstocks and the analytical monitoring of wastestreams F EAT U R E C G A Green Chemistry October 1999 G131 This journal is © The Royal Society of Chemistry, 1999G132 Green Chemistry October 1999 This journal is © The Royal Society of Chemistry, 1999 F E AT U R E C G been developed in Russia.As for the membrane bioreactor application, the high flux PTMSP organophilic membranes have been developed and the pervaporation technique has been integrated into the 0fermentation processes for solvent removal during both batch and continuous ethanol and ABE fermentations (Figure 1).Pervaporative removal of inhibitory/target product promotes cell mass growth and, as a consequence, higher sugar consumption. New effective membrane processes can be created based on membrane contractors (Figure 2).For example, membrane systems with microbiological carriers (another type of membrane bioreactor) can offer not only the selective transport of the components of gas mixtures but also their transformation into useful products. For example, it is expedient to use a closed biomembrane system for the processing of organic wastes and regulating the composition of a gas phase with extraction of valuable gas components. The systems (three blocks) includes several main components: a suspension of microorganisms and a set of nonporous polymer membranes.The first block accumulates a biomass by blue-green algae with absorption of carbon dioxide and evolution of oxygen upon the action of light. Spirulina platensis as a microorganism culture can be used.In the second block, the community of anaerobes, methanogens, and acetogens absorb the algae biomass from the first block and process it to soluble organic compounds, as well as to methane and carbon dioxide. The third block is intended for processing of simple organic compounds using non-sulfuric purple bacterium (Rhodobacter capsulata) or heterotrophic bacterium (Terhydrogenium kirishi) with conversion to a mixture of hydrogen and carbon dioxide.This system will produce hydrogen, oxygen, methane, and other useful gases of high-purity grade. The resulting biomass can be returned to the second part of the system and partially used as an additional feed or fertilizer. At present, a considerable amount of research is being done in the field of analytical chemistry.In order to effect changes of processes during their operation, one need to have accurate and reliable sensors, monitors, and analytical techniques to assess the hazards that are present in the process stream. For this purpose, the analytical techniques that are being developed can be used both in-process and in real-time.If the sensors are coupled directly with the process control, this hazard minimization may products. Therefore, many organizations are interested in developing technologies for the production of chemicals and fuels from renewable sources, and replacing the use of non-renewable petroleum feedstocks. The ethanol and ABE (acetone– butanol–ethanol) fermentation processes are very attractive as means of chemical and fuel production from biomass.In either case, the final product must be recovered and isolated in a useful form, preferably using a low-energy process. On this basis, several integrated product removal membrane techniques have been investigated for solvent removal. Organophilic pervaporation has been considered as a promising membrane technique.In addition, the membrane bioreactor concept (continuous removal of inhibitory product) allows the fermenter to be run at low steady-state solvent concentrations and improves the productivity of the fermentation. However, the low membrane flux characteristic of common membrane materials limits the commercial potential of pervaporation technology. Thus, high membrane flux is a key performance criterion that determines the cost of a membrane system.Poly(1-trimethylsilyl-1-propyne) (PTMSP) is a polymer exhibiting extremely high permeability for gases and vapors of organic compounds and high mechanical and film-forming properties. Application areas of PTMSP include gas and vapor separation and pervaporation. Catalytic processes of PTMSP, preparation with controlled characteristics, ensuring preparation of flat-sheet and hollow-fiber membranes with significantly improved stability, have Figure 1 Figure 2C G Green Chemistry October 1999 G133 This journal is © The Royal Society of Chemistry, 1999 F E AT U R E administration using hydrogel matrices.In creating a new peroral insulin preparation (Figure 3) we took into account all the experience gained in this field and the achievements of biospecific chromatography. In order to protect the useful hormone against proteolytic enzymes, we used a water-swelled polymeric hydrogel containing chemically bound (and, hence, not very well be automated.Nowdays, various types of sensors: electrochemical, semiconducting, calorimetric, biological, optical, piezosorption, etc. are developed and manufactured.Among them, the most simple and cheap are sensors of mass-metric type, or quartz microbalance, whose operation quality is mainly determined by a coating applied on electrodes of a piezoresonator (piezocrystal), the so-called sensitive layer. The possibility for using various polymers as sensitive membrane layers for chemical sensors–gas analysers can be proposed: Si-containing polymers with good membrane properties that can be used to determine the concentration of hazardous vapors in the range 0.05–1 gm-3; transition-metal complexes with N- and O-containing polymers useful for the determination of a concentration of 1,1-dimethylhydrazine with a detection limit of 1 mg m-3; modified polycarboxylic acids for the determination of NH3 with a detection limit of 5 mg m-3.There are many medical-related problems that can be solved only by employing membranes. Success of the modern membrane technology in the field of artificial organs, for example artificial kidneys, provides the most appreciable sale capacity in the world. This triggers an idea about the further development of membranes in medicine.The systems for targeted drug delivery are also promising and we are close now to solving the problem of insulin oral washed-out to the environment) inhibitors of these enzymes and insulin in the free state. The polymeric hydrogel was additionally modified by polysaccharide. Upon peroral administration, the hydrogel species travel in the digestive tract and pass the esophagus and stomach to reach the small intestine. During this passage, insulin is reliably protected against the action of penetrating proteolytic enzymes, because these are bound with an immobilized inhibitor.On reaching the intestine, the hydrogel species are accumulated on the walls as a result of the biospecific interaction of polysaccharides contained in the hydrogel with lectins of the mucous membrane. In what follows, the hormone diffuses from the volume of hydrogel immediately toward the blood capillaries and enters the circulatory system. Note that insulin enters, like the hormone produced by natural secretion, into the portal vein; that is, the liver directly takes part in the control of the insulin dose delivered to the circulatory system. It might be expected that in future ‘smart’ polymers, which are sensitive to a variation in temperature, pH, electromagnetic field, etc., will be involved more extensively into the membrane field. Moreover, systems controlled by neuromediators or hormones will be elaborated. No doubt, these inventions will allow us to approach living systems developed during prolonged evolution in nature. Figure 3 Portable gas-analyzer for air pollution control: detection limit, 1–10 ppm.

ISSN:1463-9262    

DOI:10.1039/a908576i

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

F O R UM C G G134 Green Chemistry October 1999 This journal is © The Royal Society of Chemistry, 1999 he British Association Festival of Science in Sheffield was the venue for the official launch of the Green Chemistry Network on Thursday 16th September. Over 80 guests from education, research, industry and the press, together with a few members of the general public, attended the lunchtime event.Professor Tony Ledwith, President of the Royal Society of Chemistry (RSC), gave the welcome speech during which he emphasised the need for all associated with the teaching, development and commercial exploitation of chemical technology to work together to create a more eco-friendly industry. He said the network had a key role to play in this facilitating process. Professor James Clark, Director of the Green Chemistry Network, described the Network’s activities and gave an overview of what Green Chemistry is all about, highlighting the multi-disciplinary approach (involving engineers and biologists) required to make the Green Chemistry movement a success.During lunch guests were able to discuss posters describing Green Chemistry in action provided by BP Amoco, Hickson & Welch, Johnson Matthey, ACTIN, Bio- Wise and the Clean Technology Groups at Nottingham and York.One of the highlights of the event was the announcement by Dr. The Hon. A H Todd, Master of Salters’ Company, of the establishment of the UK Green Chemistry Awards. These awards, sponsored by the RSC, Salters’ Company, The Jerwood Charitable Foundation, DTI and DETR, are aimed at encouraging more research in Green Chemistry, sharing of best practice by industry and publicly acknowledging advances being made by UK industry and research base.Full details of these Awards, which will be administered by the GCN, and how to apply appear on page G136 of this issue of Green Chemistry. Lord Sainsbury, UK Minister for Science, commenting on the GCN launch, said: ‘The need for environmental good practice in industry is already changing the way we work.Our increasing understanding of the science of our environment will continue to drive this change. I am therefore delighted that this week the Royal Society of Chemistry will launch the Green Chemistry Network and associated journal entitled Green Chemistry. This UK network will promote the principles and practice of Green Chemistry.It will also provide a very welcome UK focus and the means for those involved in industry, research and teaching of chemistry to work together to ensure that chemistry based industries of the future are more eco-friendly and sustainable.’ The Green Chemistry Network aims to promote awareness and facilitate education, training and practice of Green Chemistry in industry, academia and schools.The GCN is based within the Centre for Clean Technology at the University of York Department of Chemistry under the directorship of Professor James Clark. For further information, contact: Mike Lancaster, Green Chemistry Network, Department of Chemistry, University of York, York YO10 5DD, Tel. 01904 434549.Royal Society of Chemistry launches the Green Chemistry Network T At the GCN launch in Sheffield, left to right: Professor Tony Ledwith (RSC President), Dr. The Hon. A. H. Todd (Master of the Salters’ Company); Professor James Clark (GCN Director).Definitions in the Executive Order Biomass is any organic material that is produced by the process of photosynthesis. It can be found in crops and crop wastes and residues, wood and wood wastes and residues, animal wastes, municipal wastes and aquatic plants. Bioenergy is any power, fuel and process for the development of chemical products derived from biomass.Green Chemistry October 1999 G135 This journal is © The Royal Society of Chemistry, 1999 President Clinton’s Executive Order on Biobased Products and Bioenergy On August 12, 1999, President Clinton issued Executive Order 13134, ‘Developing and Promoting Biobased Products and Bioenergy’. The goal of the directive is to further the development of a comprehensive national strategy that includes research, development, and private sector incentives to stimulate the creation and early adoption of technologies needed to make biobased products and bioenergy cost-competitive in national and international markets.The targeted goal is to triple U.S. use of biobased products and bioenergy by 2010. The focus of green chemistry is the design of chemical products and processes that reduce and/or eliminate the use and/or generation of hazardous substances. A number of contributors to the field of green chemistry have made important contributions toward the goals of the executive order. In fact, the discovery, development, and commercialization of biobased products and processes has consistently been an active area of research and development in green chemistry as evidenced by work presented at Gordon Research Conferences on Green Chemistry and the annual Green Chemistry and Engineering conferences and published in the Green Chemistry Journal.Several of the U.S. Environmental Protection Agency’s Presidential Green Chemistry Challenge Awards have gone to individuals whose research and development efforts facilitate the use of renewable feedstocks and the synthesis or production of biobased products. According to the executive order, current technology for biobased products and bioenergy has the potential to provide affordable electricity, fuel, chemicals, pharmaceuticals, and other materials from renewable farm and forestry resources. Investing in these technologies should create new markets for farm and forest C G F O R UM waste products and economic opportunities for underused land, creating new value-added business and employment opportunities for farmers, foresters, ranchers, and other businesses in rural America.Through the development of biobased products, there is also the potential to reduce dependence on foreign oil, improve air quality, water quality, and flood control, decrease erosion, and help minimize net production of greenhouse gases. National Sustainable Fuels and Chemicals Act of 1999 U.S. Senate Agriculture, Nutrition and Forestry Committee Chairman Dick Lugar introduced legislation creating a novel research initiative focused on producing fuels and chemicals from a wide variety of plants, trees, grasses and agricultural residues.The bill was written to amend the National Agricultural Research, Extension, and Teaching Policy Act of 1977 to authorize research to promote the conversion of biomass into biobased industrial products.It passed the Committee on Agriculture, Nutrition, and Forestry unanimously and is now being prepared as a report to Congress. The bill is supported by 15 Senators of both parties. This Act is known as the ‘National Sustainable Fuels and Chemicals Act of 1999’. In the proposed legislation, `biomass’ is defined as any organic matter that is available on a renewable or recurring basis, including plants, trees, grasses, agricultural crops and residues, wood and wood residues, municipal waste, animal waste and residues, and aquatic plants.The term ‘biobased industrial product’ means any power, fuel, feed, chemical product, or other consumer good derived from biomass. According to Lugar, the conversion of biomass into biobased industrial products offers outstanding potential for improved strategic national security and balance of payments, healthier rural economies, improved environmental quality, nearzero net greenhouse gas emissions, technology export, and sustainable resource supply.It is expected that biobased chemicals could provide functional replacements for essentially all organic chemicals that are currently derived from petroleum; and have clear potential for environmentally benign product life cycles.DOE Support Bioenergy Executive Order Following President Clinton’s Executive Order on Bioenergy unveiled on 12 August, U.S. Secretary of Energy Bill Richardson announced the following day more than $13 million in financial assistance to promote the growth of the biomass industry (http://home.doe.gov/news/ releases99/augpr/pr99216.htm).Findings and recommendations The findings and recommendations of the following reports and publications are relevant to the executive order: l the recently released National Academy of Sciences report ‘Biobased Industrial Products’; l ‘Technology Vision 2020: The U.S. Chemical Industry’ by the American Chemical Society, American Institute of Chemical Engineers, Chemical Manufacturers Association, Council for Chemical Research, and the Synthetic Organic Chemical Manufacturers Association (http://membership.acs. org/I/IEC/docs/chemvision 2020.pdf) l ‘Plant/Crop-based Renewable Resources 2020: A Vision to Enhance U.S.Economic Security Through Renewable Plant/Crop- Based Resource Use;’ (a consortium of contributors from U.S.agricultural, forestry, and chemical communities, available through the Department of Energy) l ‘Agenda 2020’ by the U.S. Forest Products Industry. The full text of the Executive Order can be obtained from http://www. pub.whitehouse.gov/urires/I2R?urn:p di://oma.eop.gov.us/1999/8/13/4.text.1F O R UM C G G136 Green Chemistry October 1999 This journal is © The Royal Society of Chemistry, 1999 Lugar’s research initiative would be jointly administered by the Secretary of Agriculture and Secretary of Energy and gives priority in funding to consortia composed of technical experts from academia, national laboratories, Federal research agencies and industry.The purpose of the cooperation and coordination is to promote research and development related to understanding the key mechanisms underlying the recalcitrance of biomass and advancing technologies that will result in large-scale commercial production of low cost biobased industrial products.Innovative in both purpose and structure, the initiative will promote integrated research partnerships as the best means of overcoming technical challenges that span multiple academic disciplines while leveraging scarce Federal discretionary spending.The bill would authorize $48 million a year for six years. Green Chemistry Teaching at York The Clean Technology Centre at the University of York has recently received funding from the RSC and the University of York teaching innovation fund to develop an undergraduate Green Chemistry practical course.The aim of this is to teach the basic principles of Green Chemistry, and to emphasise the increasing importance of environmental considerations to the chemical industry. The mini-projects will be designed to follow a common structure including: l introduction and planning l practical l interim workshop and literature search l practical l review workshop and write-up The first stage of the mini-project will involve a workshop in which the students are taught the basic principles of Green Chemistry, including waste minimisation, atom efficiency and life cycle analysis.They will then choose from a broad selection of existing chemical reactions (including the option to suggest a reaction of their own preference), and, with assistance, plan a practical based on previously reported procedures.In stage 2, students will carry out the chemical synthesis using traditional methods but, in addition to the familiar tasks of isolating the product and measuring its yield and purity, they will be expected to record data on the waste produced (spent reagents, unrecovered solvents, by-products). Stage 3 will involve improvement of the process, using a hierarchical template for analysis of the chemical reaction.This will start with questioning whether another, less environmentally demanding, chemical might be able to perform the same function as the target function; i.e. is a polluting chemical actually necessary at all? Consideration will then be given to the impact of the starting materials and the conditions of the chemical transformation itself, including the solvent, temperature, catalyst and other reagents.The assessment will also cover other considerations such as the economics of the process, transport considerations, and whether any of the reagents might be from renewable sources. This will probably be the most demanding part of the project and so, as well as receiving advice from tutors, the students will be guided through the process by a series of questions and calculations. They should now be in a position to design a new set of reaction conditions, and test them experimentally (after approval by a member of staff).In this second practical the student will again record product yields, selectivities, waste quantities and consider the potential for recovery of any of the waste components.Finally, the students will compare the two processes and review the improvements that have been made, and how these might be translated to an industrial scale. If any readers wish to know more about these projects, or have suggestions for reactions which might be suitable for study, they can contact Stewart Tavener at the Department of Chemistry, University of York, or by e-mail (sjt4@york.ac.uk) Kenneth G Hancock Memorial Student Award in Green Chemistry The Hancock Memorial Award provides an opportunity for undergraduate and graduate students in the United States to compete for a prestigious memorial scholarship in recognition of their studies and/or research in green chemistry. The award provides a monetary sum and national recognition for outstanding student contributions to furthering the goals of green chemistry.Applications must address one or more of the following three green chemistry focus areas: l The use of alternative synthetic pathways for green chemistry l The use of alternative reaction conditions for green chemistry l The design of inherently safer or less toxic chemical products.The application, which must take the form of a report of no longer than 6 pages, should be sent to the Office of Pollution Prevention and Toxics, US EPA, Washington DC 20460 and marked for the attention of Tracy Williamson (room 338, East Tower). Further information can be obtained by calling 202 260-2659. This annual award is in honour of Kenneth Hancock, the late Director of the Division of Chemistry at the National Science Foundation, who was one of the architects of the ‘Environmentally Benign Chemical Synthesis and Processing’ approach to the manufacture of chemicals.The next deadline for the awards is February 1, with the awards being at the 2000 Presidential Green Chemistry Awards Ceremony in Spring 2000 in Washington DC.Green Chemistry Network to administer UK Green Chemistry Awards UK Awards for Green Chemistry have been established supported by the RSC, Salters’ Company, the Jerwood Foundation, DTI and DETR. The announcement and first call for nominations was made by Dr. The Hon. Sandy Todd, Master of Salters’ Company, at the Green Chemistry Network Launch meeting in Sheffield on 16th September.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. A similar scheme run in the US (US Green Chemistry Presidential Awards) has met with considerable success and has led to greater openness by industry of progress being made. Awards will be made both for academic research and commercial development by industry of Green Chemical Technology.Full details of the awards and how to enter are given below. Administration will be carried out by the GCN at the University of York with an expert panelC G Green Chemistry October 1999 G137 This journal is © The Royal Society of Chemistry, 1999 F O R U M The remaining 6 pages may be used to describe the Green Chemistry technology involved together with how the nomination meets the selection criteria. Please note that all entries received will be considered public information. Nominees are encouraged to be as open as possible when describing the chemical technology and environmental benefits.It is important to give enough information to enable the selection panel to make an informed judgement both on the scientific merit of the technology, the more general applicability of the technology and of the potential environmental benefits involved.Three copies of all entries must be submitted to:- Mike Lancaster Manager— RSC Green Chemistry Network Department of Chemistry University of York Heslington York YO10 5DD To be received no later than 31st March 2000.All qualifying entries will be judged by an expert panel, appointed by the RSC and Salters’ Company, with winners being informed by the end of September 2000. All winners will be expected to give a presentation of their work at an appropriate RSC conference and to submit a paper to Green Chemistry. Self-nominations are allowed and encouraged. There is no standard entry form or entrance fee.Entrants must submit a report (maximum 8 sides). The report should include the following: l A front page containing the project title, the person (to whom all correspondence will be addressed), the organisation’s address (if applicable) and other contributors (organisations or individuals who have contributed financial or technical support towards the project). 2 A second page containing: l Statement indicating whether the nomination is for the academic or industrial awards. If the nomination is for the industrial awards a statement indicating whether the organisation is eligible for inclusion in the SME award category l Project title l Statement confirming that the nominated Green Chemistry technology has been demonstrated, implemented or researched during the last 5 years, within the UK as appropriate l An abstract of not more than 400 words briefly describing the nominated project, highlighting the Green Chemistry concepts and environmental benefits involved 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.There are three Awards, namely: l An Annual Academic Prize of £10,000 to a young academic, preferably working in collaboration with industry. This Prize is known as the Jerwood Salters’ Prize and is sponsored by the Salters’ Company with the generous financial support of the Jerwood Foundation . l Two Annual Awards to UK companies for technology, products or services,one company at least being a Small or Medium Enterprise (SME as defined by DTI guidelines). These awards consist of a trophy and certificate.Selection Criteria 1. The nominated Green Chemistry technology should offer significant improvements in chemical processes, products and services through research and commercial exploitation of novel chemistry; so to achieve a more sustainable, cleaner and healthier environment as well as creating competitive advantage.Examples include: l Innovative chemistry to reduce environmental impact of products and processes. l Waste reduction at source during manufacture or processing of chemical roducts. l Reduction in the toxicity, flammability or explosion potential of substances entering the environment. l Improving the use of natural resources such as renewable feedstocks. l Improving the efficiency of energy or other utility utilisation during manufacture or processing of chemicals. 2. The technology must have reached a significant milestone during the last 5 years, within the UK (for example, for Industry Awards the technology should be in development or commercial use, for the Academic Prize the key technology steps should have been researched and demonstrated or patents applied for). 3. The technology should be generally applicable to a broad-based segment of chemical manufacturers, users or society and key features of the technology should be readily transferable. 4. The technology should be original and of high scientific merit. 5. For the Academic Prize the nominee should normally be a UK resident under 35 years of age and have developed the technology in cooperation with a company with operations in the UK. 6. For the Industry Awards, the company should have significant manufacturing and/or research facilities in the UK. How To Enter

ISSN:1463-9262    

DOI:10.1039/a908577g

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

F EAT U R E C G G138 Green Chemistry October 1999 This journal is © The Royal Society of Chemistry, 1999 here is a perception of a need for revolutionary change in technology to introduce commercial ‘green’ chemistry. Industrial experience is, however, that whilst a revolution is sometimes necessary to find ‘green’ as opposed to ‘end of pipe’ solutions, often there is much that can be achieved by an innovative evolutionary strategy applied to existing technology. A good illustration of this mixed approach is illustrated by a review of the last decade of progress in the manufacture of stilbene-based fluorescent brightening agents.These are produced on a ca. 100,000 tpa scale world-wide, with Ciba-Geigy (EU and USA), Sigma (Italy) and Hickson & Welch Ltd. (UK) as some of the major producers.Waste and emission problems figured in many of the processing stages since production began in the 1950s. As one of the few fully integrated producers, working until recently from basic toluene to finished fluorescent brightener, over a 7-stage sequence (see scheme opposite), Hickson & Welch’s processing perspective contains some interesting lessons, showing evolution to be as important and effective as revolution in side-stepping ‘green’ challenges at minimum additional cost.Such additional costs can, of course, be either from additive ‘end-of-pipe’ processing equipment and costs, or from major reinvestment in entirely new ‘green’ technology. Each step shown in the scheme is described below in numbered sequence, and the ‘green’ revolutionary and evolutionary options described.Step 1 Toluene is conventionally mononitrated with mixed sulfuric/nitric acids, adjusted to 80% sulfuric acid strength with water. The spent mixed acid was separated and discharged to waste, and the mixed mononitrotoluene isomers washed with sodium hydroxide solution to remove ca. 0.5% phenolic and oxidation products. The alkaline washings are discharged to waste.The washed mononitrotoluenes are fractionally vacuum-distilled at high temperature to isolate pure p-nitrotoluene. Unwanted by-products from the still base are incinerated. Problems l There is heavy output of ‘spent’ contaminated 70% sulfuric acid wastes to low grade acid users such as the coking and steel industries. l The high output of dilute nitrophenol sodium salt washings is toxic to biotreatment systems.l There is high energy consumption in sulfuric acid production and hightemperature vacuum distillation. The ‘Green’ chemistry solution The vision over many years has been the direct nitration of toluene with nitric acid using catalysts such as modified clays, which are known to be capable of producing high proportions of the higher value p-nitrotoluene isomer (conventional mixed acid gives 65% of the saleable but lower value o-nitrotoluene isomer).The problem is that the water of reaction released from direct nitric acid nitration tends to degrade the catalyst. Hickson piloted such technology using reduced pressure distillation to strip reaction water from the heterogeneous catalyst continuously.Rapid evolutionary progress on the conventional technology made the planned reinvestment and switch uneconomic, however. The evolutionary approach The disappearance of the demand for ‘used’ sulfuric acid in the coke and steel Green Chemistry— evolution or revolution? T Stuart Cook of Hickson and Welch describes how an elderly multistage production process has been made more green by an innovative evolutionary strategy applied to existing technology The manufacture of optical brighteners used in today’s washing powders, is a good example of green chemistry evolution.Green Chemistry October 1999 G139 This journal is © The Royal Society of Chemistry, 1999 industries threatened to undermine process economies.Installation of an acid recovery unit enabled a closed cycle to be established, the sulfuric acid becoming effectively a reusable catalyst.As the reaction starts at 80% H2SO4 and discharges at 70% H2SO4, only a proportion of the acid needs be recovered to 99% strength, and mixed with 99% nitric acid and 70% spent acid to achieve the necessary 80% starting strength. This ‘spent acid’ recycle improves recovery economics.The need for thorough wastewater biotreatment threatened to demand reacidification and solvent backwashing of all alkaline wash liquors, to remove nitrophenols for separate incineration. For manufacturers pursuing this route it can cost almost as much in capital and operations to acidify and backwash the waste as making the mixed mononitrotoluene itself (and the extracts still need incineration).Hickson demonstrated and ran for 10 years a process which entirely omitted the alkaline wash and consequent activity. This omission gives wash waters so low in nitrophenols as to be readily biodegradable. The mononitrotoluene preferentially holds phenols unless alkali is added, and the phenols then exit in the still-base oils. Less saleable mononitrotoluenes in fact need to be left in still-base oils for burning, an added economic advantage.The strong ‘folklore’ that the phenols cause instability in stills was shown by detailed investigations to be totally unfounded. One of the major hazards in nitrotoluene manufacture is, in fact, the entry of sodium phenolates into the high temperature (ca. 190 ºC) nitrotoluene stills because of poor washing.Explosions have been thus caused. The new system eliminated this hazard. The phenols, as opposed to their sodium salts, are stable. The effect of these changes eliminated the prospect of waste acids and nitrophenol wastes undermining the process economics and improved rather than added to process costs overall. Evolution rather than revolution both eliminated environmental threats and improved process waste/energy/yield economies.Step 2 p-Nitrotoluene is sulfonated by adding 25% oleum to the liquid mononitrotoluene, then adding the mixture to water to give the optimum 50% sulfuric acid strength for filtration of the solid sulfonated product which precipitates. The wet cake is redissolved in water for subsequent use. Problems Large volumes of waste acid filtrate are generated.The reaction mixture is thermally unstable and this limits reaction rates and temperatures when large batch processing inventories are involved. Large volumes of relatively dilute oleum are necessary to provide both heat-sink and sufficient drowned out 50% acid to give a stirrable product slurry for filtration. Higher strength oleum gives not only overviscous slurries upon precipitation, but also undesirable highly coloured by-products unless excellent mixing is achieved during sulfonation.The ‘Green’ chemistry solution p-Nitrotoluene can be sulfonated with gaseous SO3 rather than oleum, eliminating all waste acid generation. This is achieved by conducting the reaction in a suitable refluxing solvent, then simply extracting the product from the recycle solvent with water to give a solution suitable for the next step.The technology is proven on significant scale. The evolutionary approach Rather than entirely reinvesting in the gaseous SO3 technology, it was in fact found possible to all but eliminate waste acid problems and simultaneously reduce process costs. C G F E AT U R E If a continuous low inventory tube reactor is adapted, much higher strength oleums can give pure product safely.The problem of producing a mobile final slurry is avoided at these higher strengths by recycling spent acid to dilute the slurries for filtration. In addition, although 50% acid traditionally gives optimum product recovery, at 70% the shape of the solubility curve and reduced volumes mean that only ca. 1% yield is unprecipitated. This is insignificant compared with savings in energy, filtration times, output and intensity gains, so 70% not 50% acid can be adopted economically once the real cost of waste acid is in the equation. The ‘traditional’ process can thus be transformed to give a small acid recycle/recovery problem, and improved economics, by evolution. Step 3 A ca. 4% p-nitrotoluene sulfonic acid solution is heated slowly to 70 ºC in the presence of ca. 4% caustic soda solution and manganese catalysts with vigorous aeration. Over ca. 20 hours there is an 80% conversion to 2,2A-dinitrostilbene 2,2Adisulfonic acid (DNS), and the solution can be neutralised, cooled and the 80% yield of ‘DNS’ filtered from the cold aqueous salt solution.F E AT U R E C G G140 Green Chemistry October 1999 This journal is © The Royal Society of Chemistry, 1999 Problems A low intensity and slow process.Very vigorous continuous aeration with excellent agitation is essential to prevent highly coloured polymeric by-products. High-energy usage is incurred for mixing and aeration and holding high temperatures during aeration (which causes evaporative cooling).The major historic issue is that filtrates are high in salt and rich in the 20% of raw materials converted to nonbiodegradable and often highly coloured benzoic acids, aldehydes and azo linked polymers. Disposal is a colour and COD (chemical oxygen demand) issue even where salts are tolerated. The ‘Green’ chemistry solution The best solution would be to raise the yield, the reaction rate and avoid air and water! Some manufacturers adopt sodium hypochlorite oxidation.This is faster, gives identical optimum yields and uses less direct energy, but only avoids the liquor and waste organics problem if yield is sacrificed and even higher salts levels are acceptable in wastes. Potential organochlorine generation is difficult to disprove, although Hickson & Welch production demonstrated no evidence of detectable organochlorines from the use of sodium hypochlorite bleach.The extra cost of hypochlorite versus air is nicely negated by the much faster and more intense process achievable. Some commercial production at enhanced yields is claimed with pure gaseous oxygen in liquid ammonia or alkylamine solvents. The technology has not been widely adopted.Flammability must be one restricting concern. Most western producers resorted to expensive and energy intensive wet air oxidation to treat the aqueous wastes at end-of-pipe. The evolutionary approach Extensive reoptimisation of process conditions using pure oxygen not air and controlling oxidation potentials in appropriate narrow band widths with optimised manganese catalysts enable reactor dilution, energy consumption and waste output to be reduced by ca. 50%, and reaction times to be substantially cut. The remaining but reduced salty waste load can be biotreated ‘as is’ with specially selected bacteria for river discharge, but the optimum is a relatively low pressure/temperature oxygenation with catalysed acid, and then more full and rapid biotreatment with conventional biomass.The evolved effect is a major capital, energy and waste treatment saving, and a process which is not only more green but more economic. Step 4 ‘DNS’ sodium salt is redissolved in water and fed slowly into a refluxing bed of iron borings and water. The resulting diamine solution is blown from the iron borings bed, filtered to remove iron oxide sludge, and acidified to precipitate the diamine, which is filtered off for use.The iron sludge filter cakes are disposed of to the steel and coke industry. The ‘Green’ chemistry solution Hydrogenation instead of iron reduction is cleaner and generates neither the need for iron borings nor disposal routes for contaminated iron oxide sludges. The evolutionary approach Although great strides were made to improve ultimate quality by iron reduction, without resorting to expensive custom made iron powders instead of scrap metals, the revolution of hydrogenation is irresistible.Platinum type catalysts are essential, and the fact that the diamine product reacts with the dinitro starting material to produce highly coloured and damaging azoxys and aldehydes poses significant challenges.Both Hickson and others have developed successful hydrogenation technologies, with major economies and sufficiently clean reactions to use the hydrogenated solutions directly without acidification/filtration. Steps 5, 6 and 7 Diaminostilbene sulfonic acid (DAS) sodium salt solution is traditionally fed slowly into a chilled solution of cyanuric chloride in acetone or methyl ethyl ketone.A base is added as the reaction proceeds to hold an appropriate pH value. Sufficient excess cyanuric chloride is used to compensate for the inevitable water hydrolysis during the slow diamine addition. Over-rapid amine addition leads to polymers with poor mixing, and accelerated hydrolysis with rising temperatures. The former is the prime risk if crushed ice is used to fix temperatures at 0 ºC, the latter if external cooling is used to maximise agitation and mixing.The resulting slurry is then treated sequentially with a further amine and alkali at 50–60 ºC, then a third amine whilst distilling out the solvent and precipitating the product and raising the temperature to 90–100 ºC. Optimum conditions give 98% yield on DAS, of 99% pure brightener! Problems l Large volumes of flammable solvents require distillation, drying and recycle. l Neutralisation by strong bases of the hydrochloric acid released as the cyanuric chloride reacts is difficult to control for optimum quality.Selfbuffering bases such as bicarbonate are convenient but give CO2 evolution and consequent VOC containment issues.l Up to 10% excess cyanuric chloride can be necessary to balance consumption in hydrolysis side reactions. If allowed to react, the part hydrolysed cyanuric chlorides give undesirable ‘off’ colours to the fluorescent products whitening effects. The ‘Green’ chemistry solution Reacting entirely in water is an obvious dream, by simply not having solvent containment or flammability issues to address.Cyanuric chloride is, however, insoluble in water and reacts with water if it does dissolve without being able to react immediately with diamine. The diamine component reacts further with the desired product if ever allowed to be in excess itself, and the desired product precipitates in pure water, tending to occlude other components. We surely cannot obtain 98% yield at 99% purity in just water with these constraints? The evolutionary approach Different fluorescent brighteners were found to pose different challenges.Those for paper and textile industries tend to be water soluble, and often sold in fact as water based solutions. By careful temperature regulation and addition of diamine to cyanuric chloride slurried in water, it is in fact possible to react the slowly dissolving cyanuric chloride before it hydrolyses in solution, but without accumulating unreacted diamine which would quickly ‘polymerise’ with the product.For over 10 years the water-soluble textile and paper brighteners have been made ‘aqueous’ by several manufacturers. Their solubility helps in terms of occlusion of raw materials inside precipitating products.It is even possibleC G Green Chemistry October 1999 G141 This journal is © The Royal Society of Chemistry, 1999 F E AT U R E to sell the entire unisolated reaction mixture as product, sometimes removing salts by membrane technology to eliminate precipitation risks in stored solutions. Detergent destined brighteners do, however, pose greater challenges, as they are water insoluble and have high purity and impurity constraints.Low molecular weight cyanuric chloride by-products (‘melamines’) can, for example, generate serious odour problems in washing powders and cannot be tolerated at more than 0.1% w/w levels. The particle size and crystal form of the precipitated brightener is also crucial to achieve good wash behaviour in detergents over a wide washing machine temperature range, and to produce a good appearance to the formulated washing powder.The absence of ‘solvent’ introduces new challenges in achieving desirable particle size behaviour. In 1998 Hickson & Welch overcame these problems and successfully introduced entirely new production technology which avoided major investments in essential solvent containment improvements, and eliminated all the fire risks inevitable with high volume solvent distillation recycle.Despite substantial progressive yield and raw material gains over recent years in solvent technology, the understandings necessary to make the entirely new water based process work also enabled even higher yields to be obtained by, for example, cutting cyanuric chloride consumption by 3–5%. Overall summary Although a revolutionary technology change was necessary in some processing stages to avoid end-of-pipe cost additions, in several other stages the evolutionary approach proved as effective, even where alternative ‘green’ technology was available in principle.The feared and anticipated additional ‘green’ costs were largely side-stepped by Hickson & Welch and the economic savings achieved did, in fact, free more resources for investment in ‘green’ infrastructures, such as a more efficient combined heat and power gas turbine system and a more modern and thorough biotreatment plant.An open mind to innovative R&D work is the secret, and the avoidance of long-term company researchers constraining new workers with an ‘it cannot be done, we tried it years ago’ attitude. Which of your processes have been worked on for years and years—and have no further development potential left in them for chemists and engineers? We were surprised what our Production and R&D teams gradually did to ‘green’ elderly processes in elegant ways. Hickson & Welch can Trace back its roots on the present Yorkshire site to 1915, and for 40 years it has been basic in the manufacture of nitrotoluenes and products based upon them. Nowadays the company employs 500 people and is increasingly specialising in the process development and manufacture of complex life science products under contract to major multinationals. The company’s successful work in reducing waste emissions has recently led to a Cremer and Warner prize, the National Crystal Award from the Green Organisation and commendation from the Yorkshire Wildlife Trust. The author graduated in chemistry from Leeds University in 1967. During a 32 year career in fine chemical process development and manufacturing he has for 10 years the R&D director of Hickson & Welch. He can be contacted on +44 (0)1977 712231 or stuart.cook@hickson.co.uk/

ISSN:1463-9262    

DOI:10.1039/a908578e

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

F EAT U R E C G G142 Green Chemistry October 1999 This journal is © The Royal Society of Chemistry, 1999 he Blue Ribbon Panel and its recommendations The Blue Ribbon Panel on Oxygenates in Gasoline was set up by the EPA in November 1998. The 13-member panel—including representatives from the petrochemical industry as well as health experts and academics—met six times before producing its report in July 1999.1 Although it found that reformulated gasoline provides ‘considerable’ air quality improvements, the panel said that ‘MTBE in drinking water supplies can and should be substantially reduced,’ and highlighted MTBE’s persistence and mobility in water.The panel stressed that its recommendations should be implemented rapidly and as a single package, but stressed that: ‘MTBE is currently an integral component of the US gasoline supply.As such, changes in its use must be implemented with sufficient time, certainty and flexibility to maintain stability of US fuel supply and gasoline prices.’ Among the panel’s recommendations are a raft of measures to prevent leaks from underground storage tanks (USTs), thought to be the major cause of ground water contamination by MTBE.The panel also recommended further research on the field performance of USTs, and the introduction of requirements to improve leak detection, monitoring and siting of tanks. The panel said that more research is also needed on modelling the behaviour of gasoline and oxygenates in groundwater, and on levels of MTBE, ethanol, benzene and other gasoline compounds in drinking water supplies.According to the EPA, MTBE has been detected in 5–10% of drinking water supplies in areas of high oxygenate, although the vast majority are below 20 parts per billion. The panel’s report drew on a $500,000 study of MTBE by the University of California (UC) in 1998.2 The UC report recommended a gradual MTBE— friend or foe? T A panel of experts has called on the US Government and the Environmental Protection Agency (EPA) to ‘substantially reduce’ the use of methyl tertiary-butyl ether (MTBE) as a fuel additive in gasoline.Becky Allen reports What is MTBE? MTBE was introduced in 1979 as a fuel additive to increase octane rating, but is now used in much higher concentrations as a fuel oxygenate to improve air quality. In the USA, oxygenated fuels are used in federal reformulated gasoline in certain areas, and in the EPA’s winter oxygenated fuels programme.Over 85% of reformulated gasoline contains MTBE, while 8% contains ethanol. There has been growing concern about its use following detection of MTBE in water supplies in California, Maine and other states. MTBE readily dissolves in water, can move rapidly through soils and aquifers, is resistant to microbial decomposition and is difficult to remove in water treatment. The EPA has not established drinking water standards for MTBE, but issued a Drinking water advisory in December 1997 of 20–40 micrograms per litre (µg/L), primarily for taste and odour considerations.Source: US Geological Survey, water.wr.usgs.gov/mtbe/ Blue ribbon panel on oxygenates in gasoline recommendations1 l improvements to US water protection programmes, including over 20 specific recommendations to reduce leaks from underground storage tanks’ l ‘substantial’ reductions in MTBE and other fuel additives l changes to the US Clean Air Act to remove the current requirement for fuels to contain 2% by weight of oxygen l EPA to seek mechanisms to ensure no loss of current air quality benefits ‘MTBE in drinking water supplies can and should be substantially reduced’Green Chemistry October 1999 G143 This journal is © The Royal Society of Chemistry, 1999 phase-out of MTBE in California, which has tougher air quality standards than the rest of the USA.According the UC report: ‘Technical advances in new automobile emission controls and combustion systems, and in new gasoline formulations, have dramatically decreased the air quality benefits associated with adding oxygenates to gasoline, making the potential for water contamination by MTBE a cost that is not offset by a corresponding benefit.’ Dissenting voices A majority of the panel agreed that improvements in leak prevention, treatment and remediation would not adequately protect drinking water supplies from MTBE contamination, and so recommended that MTBE use be reduced. Two members of the panel, however— Todd Sneller of the Nebraska Ethanol Board and Debbie Starnes of Lyondell Chemical—disagreed with the recommendation to limit use of MTBE.According to Starnes, the recommendations would cost $1–3 billion a year to implement.‘The panel did not identify any increased public health risk associated with MTBE use in gasoline. No quantifiable evidence was provided to show the environmental risk to drinking water from leaking underground storage tanks (LUST) will not be reduced to manageable levels once the 1998 LUST regulations are fully implemented and enforced . . . Unfortunately, there appears to be an emotional rush to judgement to limit the use of MTBE,’ she said.Sneller’s objections centred around the panel’s assessment of the air quality benefits of oxygenates. ‘The panel’s report concludes that oxygenates fail to provide overwhelming air quality benefits associated with their required use in gasoline. The panel recommendations, in my opinion, do not accurately reflect the benefits provided by the use of oxygenates in reformulated gasoline,’ Sneller said.The panel found that reformulated gasoline substantially reduced vehicle emissions of volatile organic compounds, carbon monoxide, benzene and 1,3-butadiene. However, an earlier report from the White House Office of Science and Technology Policy found that MTBE use can result in increased emissions of formaldehyde and nitrogen dioxide, and attributes falling carbon monoxide levels in US cities over the past 20 years to better vehicle emission control technology and tougher standards.3 Conclusion The Blue Ribbon Panel’s conclusion highlights the complex decision-making process involved in substituting one chemical for another, if gains to one part of the ecosystem are not be made at the expense of another.‘The introduction of reformulated gasoline has had substantial air quality benefits, but at the same time raised significant issues about the questions that should be asked before widespread introduction of a new, broadly-used product. The unanticipated effects of reformulated gasoline on ground water highlight the importance of exploring the potential for adverse effects in all media and on human and ecosystem health, before widespread introduction of any new, broadly-used, product,’ the panel says.C G F E AT U R E Mixed reception for the report Some organisations like the Clean Fuels Group, the renewable Fuels Association and the American Water Works Association have welcomed the report, while others, like the Oxygenated Fuels Association and the National Petrochemical and Refiners Association, have expressed reservations and concerns over its recommendations.Members of the Blue Ribbon Panel Dan Greenbaum, Health Effects Institute (Chair) Mark Buehler, Metropolitan Water District, South California Robert Campbell, Sun Oil Patrick Ellis, Delaware Department of Natural Resources and Environmental Conservation Linda Greer, Natural Resources Defense Council Jason Grumet, NESCAUM Anne Happel, Lawrence Livermore National Laboratory Carol Henry, American Petroleum Institute Michael Kenny, California Air Resources Board Robert Sawyer, University of California, Berkeley Todd Sneller, Nebraska Ethanol Board Debbie Starnes, Lyondell Chemical Ron White, American Lung Association ‘the panel recommendations do not accurately reflect the benefits provided by the use of oxygenates in reformulated gasoline’ (Sneller) ‘there is a complex decision-making process involved in substituting one chemical for another’ References 1.Blue Ribbon Panel on Oxygenates in Gasoline: Executive Summary and Recommendations, 27 July 1999, http://www.epa.gov/oms/consumer/ fuels/oxypanel/blueribb.htm 2. University of California Report on MTBE, 12 November 1998, http://www.tsrtp.ucdavis.edu/mtberpt 3. Interagency Assessment of Oxygenated Fuels Final Report, The White House Office of Science and Technology Policy, June 1997, www.epa.gov/oms/consumer/ fuels/oxypanel/blueribb.htm

ISSN:1463-9262    

DOI:10.1039/a908579c

出版商:RSC    

年代:1999

数据来源: RSC

摘要:

F EAT U R E C G G144 Green Chemistry October 1999 This journal is © The Royal Society of Chemistry, 1999 ntroduction Until the Bhopal Gas Tragedy in 1984, there were few courses and few researchers in chemical process safety around the world. That tragedy shook everyone out of complacency: the public, media, legislators, judiciary, academics, NGOs (non-governmental organisations) and the process industry.Now there are more courses, more researchers, more research journals, more conferences and more legislation on process safety and loss prevention. The result, to quote Trevor Kletz,1 is that ‘the loss prevention movement has prevented many hundreds of deaths’. Considering that for each fatality, there are 2–3 serious or permanent injuries, many more minor injuries, together with trauma and economic loss, the value of loss prevention can be appreciated. With interest in the field of loss prevention aroused, should chemical process industry (CPI) be content with minor improvements? No! Although most of the public accept that chemicals are essential to their way of life, they are at the same time looking to the CPI to get its safety act together—fast.Fortunately for the CPI, Trevor Kletz propounded the concept of Inherently Safer Design (ISD) over 2 decades ago—a concept which has been accepted very gradually by the CPI and other stakeholders. There have been several research papers, books and conferences on the topic.2–7 ISD has been defined as ‘Any improvement in a layer of protection which is permanent and inseparable and not easily weakened or removed from the system’.5 It has been divided into the following five categories: l Intensification or minimization of the amount of hazardous material present at any given time, be it in a reactor, pipeline, transport vehicle or storage tank.For example, use of continuous tubular reactors instead of a large batch reactor. l Substitution of a hazardous material by a less-hazardous or non-hazardous one.Replacement of flammable organic solvents by water is an example. l Attenuation or toning down of the operating conditions of pressure, temperature, concentration, etc. For example, over several decades, the pressure in ammonia synthesis has come down from several hundred bar to about one hundred bar. l Limitation of the effects of any hazard materializing by bunds, fence wall, judicious layout, siting away from habitation, etc. l Simplification of the plant.Simpler plants are easier to design, fabricate, erect, operate, control and maintain. Such inherent safety aspects do not require periodic testing, maintenance or replacement, as is the case with the Inherently Safer Design— a course for science and engineering students* I J.P. Gupta (email jpg@iitk.ac.in) from the Indian Institute of Technology in Kanpur in India outlines the value of a one-semester training course in applying the principles of inherently safer design to chemical process safety Currently Professor of Chemical Engineering at the Indian Institute of Technology (IIT) Kanpur, India, Dr. Gupta worked as a research engineer with UOP Des Plaines, USA (1967–68) in petroleum refining operations and taught at the University of Pennsylvania, Philadelphia, USA (1971–72) before joining IIT Kanpur in 1972.He has been a consultant to companies in India and USA. His teachings and research have been in the areas of transport phenomena, unit operations, design of process equipment, chemical plant safety, hazard analysis and disaster management. He teaches courses on these topics to students as well as to practising engineers from Industry and has helped start such courses in India and abroad.* Adapted with permission from a talk on ‘Teaching Inherently Safer Design to meet the Safety Needs of CPI in the Next Millennium’, Keynote lecture delivered at the National Safety Council Seminar on ‘Safety and Health-Challenges in the next Millennium’, Taj Mahal Hotel, Lucknow, India, July 16, 1999.Green Chemistry October 1999 G145 This journal is © The Royal Society of Chemistry, 1999 add-on or engineered safety items.There will, however, be a continued need for engineered (or add-on) safety, since some activities are better done that way, and some activities will not be made as safe as is reasonably possible by ISD alone.The proportion of (and hence the cost and probability of failure of) add-on safety will nevertheless reduce as more people start to practise ISD. Basically, ISD requires questioning in an unbiased and thorough manner all the steps from choosing a product, process to produce it, design and layout of equipment and control systems, operating conditions, transporting product to the market and its use by consumers.Inventories at each step must also be carefully considered since so much money is tied up in them, and they can cause significant damage and casualties due to fire, explosion and toxic release. The cases of Bhopal and Mexico City are still fresh in the memory. The present author firmly believes that if ISD principles are followed along with process miniaturization as forcibly argued by Benson and Ponton9 the CPI in 2020 will look a lot different and friendlier.Equipment sizes will be smaller due to higher efficiency and distributed production at the customer site. Operating conditions will be less severe due to the development of better catalysts and friendlier process routes, and inventories will be significantly smaller following the ‘just-in-time’ principle, to the extent the infrastructure can support it. All of this will reduce the capital cost and costs related to operation (less energy, personnel requirements), inventory size, maintenance, process upgrading, transport of raw material and products, environment protection and decommissioning of the plant at the end of its useful life.The key to achieving all the above is spreading the word about ISD, practising it vigorously—one may even say ruthlessly—and publicizing the gains obtained (keeping in mind the inventor company’s desire to maintain confidentiality to recover its expenditure and more). For any idea to spread, it has to be taught at the earliest, appropriate stage.In the case of ISD, the appropriate time is the first-degree course in science and engineering. I describe a one-semester course on ISD. For engineers and scientists to apply ISD principles, support from the organisation bosses is essential,10 because ISD challenges the status quo in design and operation, and management need to be persuaded to consider doing things differently. The concepts of ISD, as stated by Kletz and further elaborated by others, are so simple and common sense that they can be understood by anyone with a basic scientific knowledge.Hence our course will benefit those in the construction, automobile, metallurgical, aviation industries, etc., until more focussed courses are developed in these areas.8 The ISD Course The one-semester course consists of 3 lecture-hours per week for 12–14 weeks; the lectures can consist of three 1-hour lectures per week, or, as the present author prefers, two 11/2-hour lectures per week.The ‘highly recommended book’ for the course is that by Trevor Kletz.2 Since there are no other ISD courses (this being the first course as far as is known) and the book was not really written as a standard textbook, it needs to be supplemented by other publications.3–7 Students need to be encouraged to study the various topics in advance of the lecture, since ISD attempts to change fundamental attitudes towards safety and current ideas on how process plants should be designed and run.Hence, reading in advance will better prepare students to understand the lectures and hopefully modify their thinking.Therefore, the instructor needs to give advance reading assignments on at least a weekly basis. The students should already know the techniques of hazard identification, risk analysis, calculation of consequences, etc. †—topics covered in a normal Loss Prevention or Chemical Process Safety courses11–14. This will help them in determining the situation both before and after the ISD principles are applied.For each topic mentioned below, it is necessary for the lecturer to give examples utilizing the related ISD methodology; such examples are quoted in the literature cited at the end of this article. Topics covered in the ISD Course Hazards in CPI Knowing these is the first step to think of ways to avoid, minimize or contain them.Selected major accidents Discussion on these brings out the potential major plants have to cause C G F E AT U R E disaster. It is preferable that students examine the case studies given by Lees11 and present them in class. The instructor may supplement these with photographs and videos, as available. It is vital to point out how these accidents could have been avoided or effects minimized by using ISD principles. For example, at Bhopal there was no need to: l use the process route that produced MIC (methyl isocyanate) as an intermediate l store so much MIC when, even with the existing process, a different reactor design would have cut the inventory of MIC to a few kilograms in the reactor with no intermediate storage of many tonnes required2 Review of ISD methodologies This should give an overview of ISD techniques and at what stage in the evolution of a plant these should be applied—actually, the earlier the better, starting at the lab process development stage, but these can be applied with advantage at just about any stage and even on the installed and operating plants.It has been well said about ISD techniques: ‘Start early and never stop’.5 Attention should then be turned to specific ISD methods with available examples provided in each case.The hazard potential of pre- and post-ISD application should be analyzed in each case to justify the application and cost of ISD. Intensification or minimization of hazardous substances This should be done at every stage possible: in storage or warehouse; in process equipment such as reactors, distillation towers, heat exchangers, mixers, etc.and in transportation. Reduced amounts of hazardous substances reduce the possible consequences of any hazard such as fire, explosion, or toxic release. Substitution of a more hazardous material by a less- or nonhazardous one The consequences of any hazard materializing would be proportionately less.This requires serious thought at the process development stage as it becomes very expensive to substitute a hazardous substance by a less hazardous one at a later stage, when add-on safety features are the only way left. According to Trevor Kletz, the life-long cost of an add-on feature is twice its capital cost † If the students do not know these techniques, they need to be taught in 8–10 one-hour lectures before starting on ISD.F E AT U R E C G G146 Green Chemistry October 1999 This journal is © The Royal Society of Chemistry, 1999 due to the need for testing, repairing and maintenance all through its life.Attenuation or moderation of operating conditions The pressure, temperature, concentration, etc. should be reduced as much as possible at every stage to reduce the consequences of any failures.At times, attenuation may run counter to intensification since reduced temperature or concentration lowers the reaction rate resulting in larger inventory in the reactor. Such situations should also be pointed out, so that ISD is used sensibly, not blindly as a panacea. Limitation of the effects of failures Siting plants away from habitation should be considered, as well as plant design and plant layout to minimise the effects of failures both on-site and off-site.Control of habitation or maintenance of a ‘green corridor’ around hazardous plants can limit the off-site effects. Simplification of plants Simpler plants are obviously easier to operate and so one should not attempt to do too many different operations in the same equipment—it involves too much piping, valves, bypass lines, etc.Wrong setting of valves, less than thorough cleaning after earlier usage, etc., can result in problems. Simpler plants also cost less to fabricate, operate, maintain and control. Other ISD techniques2 l design plants to be error-tolerant l avoiding the domino effect l making incorrect assembly difficult l provide easy control of a process Software safety Computers have just about taken over the control of all major CPI, with software generally written by nonchemical engineers.Software errors can be significant, especially in new or one-of-a-kind software, and these must be thoroughly tested. Examples of disasters caused by software errors are available.15,16 Use of indices to rate ISD DOW, Mond and PIIS (Prototype Index of Process Safety, Loughborough University) can be used to rate the effects of ISD techniques.Other indexing techniques may also be developed in due course as more experience is gained in ISD. Life cycle approach Consider all aspects from R&D, process development and design, plant erection and commissioning, operation, modifications, attention to upset conditions, maintenance and decommissioning after the plant has run its useful life, applying ISD principles at each stage.R&D needs The R&D in process safety has not kept pace with the need.17 It is very important to emphasize this and point out areas in need of R&D. Depending upon availability of laboratory facilities and background of the students, some of these could be given as a semester project, under close supervision since students will not have much experience in laboratory safety.Decision making regarding ISD usage Why is ISD taking so long to be accepted? Answers to this might include: conflicts of ISD with environmental regulations, trade-offs between ISD and other techniques, etc.Also, warn the students that the applicability of ISD techniques should be thoroughly investigated lest they should create a different set of hazards. Maintenance of Records2,10 Many decisions on process safety and application of ISD are taken based on sound principles, knowledge and experience, but the people making the decisions eventually move on. New hands might be tempted to alter the system by tinkering here and there, or in one big push.Accidents are likely to happen if reasons for decisions made years ago are not known. Hence, it is most important to record the reasons and calculations done for each decision and design. Before making any change, reasons for the existing design, operating conditions, etc., must be known. This will avoid accidents and much grief later on.Students should therefore be asked to write in simple and understandable terms the changes they propose in any class exercise design using ISD concepts. Since ISD is a relatively new field, it is not easy to offer a full course in it, and it is still less easy to examine student performance in it. The teacher will have to devise innovative ways to test a student’s grasp of the topics.Experts from nearby industries can be helpful in testing by proposing real problems to which the students may be asked to apply ISD techniques. Since there will not be one correct answer in most cases, grading of students’ responses will also have to be innovative. It should not mar a student’s interest in ISD for the rest of his/her life.That would arrest the progress of ISD more than the teaching of the course would advance it! It is strongly recommended that the students should be taken on a tour of at least one safety-conscious large CPI about two-thirds of the way through the course. The chosen industry’s reactants, products, processes, operating conditions, annual production, customer location, etc., should be discussed beforehand to the extent that the company’s commercial and technological confidentiality considerations allow.This would prepare the students to apply ISD principles after viewing the plant personally. Company personnel should be on hand to discuss the students’ recommendations on the use of ISD in their plant; both the company and the students will gain. If students have not had a process safety or loss prevention course, then they first need to learn the following topics for hazard analysis.This will help them analyze the benefits and costs of applying ISD methodologies: l HAZOP l Dow and Mond Indices l Fault-tree Analysis and Event-tree Analysis l Pool Fire, Fire Ball and Explosions l Gas Dispersion Students need only simple models and examples since their aim is to compare the pre- and post- ISD systems.Conclusions Teaching of ISD will spread the message and give new insights to future designers. While this article has dealt with a onesemester course, the same has also been Recommended journals on chemical process safety The Chemical Engineer, IChemE (UK) Journal of Hazardous Materials, Elsevier Journal of Loss Prevention in the Process Industry, Elsevier Loss Prevention Bulletin, IChemE (UK) Loss Prevention News, Loss Prevention Association of India Process Safety and Environmental Protection, Trans IChemE, Part B Process Safety Progress, AIChEC G Green Chemistry October 1999 G147 This journal is © The Royal Society of Chemistry, 1999 F E AT U R E repackaged for practising engineers as a 3-day short course.The vast experience of these practising engineers will produce intense interaction and will be extremely helpful in further refinements of the fullsemester course as well as in more committed practice of ISD. References 1. Trevor Kletz, ‘The Origins and History of Loss Prevention’, Trans. IChemE, 77, Part B, 109–116 (May 1999). 2. Trevor Kletz, ‘Process Plants: A Handbook for Inherently Safer Design’, Philadelphia: Taylor & Francis, (1998) and numerous other books and papers by him. 3. Center for Chemical Process Safety, ‘Inherently Safer Chemical Processes––A Life Cycle Approach’, ed. D. A. Crowl, New York: CCPS/AIChE (1996). 4. ‘Proceedings of the International Conference and Workshop on Process Safety Management and Inherently Safer Processes’, Orlando, Florida, Oct. 8–11 (1996). New York: CCPS/AIChE. Also proceedings of other conferences organized by CCPS, IChemE, etc. 5. Dennis C. Hendershot, ‘Inherently Safer Plants’, Chapter 2 in ‘Guidelines for Engineering Design for Process Safety’, New York: CCPS/AIChE (1993) and numerous other papers by him. 6. Stanley M. Englund: ‘Design and Operate Plants for Inherent Safety’, Chemical Engineering Progress, 87, Part 1: 85–91, (March 1991).Part 2: 79–86 (May 1991) and other papers by him. 7. Colin Ramshaw, ‘Process Intensification and Green Chemistry’, Green Chemistry 1(1), G15-G17 (1999) and many other papers by him containing lots of ISD developments carried out by him and his team. 8. J. P. Gupta, ‘Inherently Safer Design in Chemistry and Chemical Engineering Education’, Green Chemistry Network Newsletter, 2, 9–10, (July 1999). 9. R. S. Benson and J.W. Ponton, ‘Process Miniaturisation—A Route to Total Environmental Acceptability?’ Trans. IChemE, 71, Part A, 160–168 (March 1993). 10. David Mansfield, AEA Technology, UK, Personal Communication (June, 1999). 11. F. P. Lees, ‘Loss Prevention in the Process Industries’, 2nd edn., Butterworth-Heinemann, Oxford (1996).Also numerous papers by Lees and colleagues. 12. D. A. Crowl and J. F. Louvar, ‘Chemical Process Safety: Fundamentals with Applications’, Prentice Hall, Englewood Cliffs, N.J., USA (1990). Also numerous papers by Crowl. 13. Bob Skeleton, ‘Process Safety Analysis—An Introduction’, Rugby, UK: IChemE (1997). 14. J. P. Gupta, ‘Hazard Analysis in Chemical Industry’, Lecture notes for a 4-day intensive course of the same title, Department of Chemical Engineering, IIT Kanpur. 15. Nancy G. Leveson, ‘Safeware: System Safety and Computers’, Addison-Wesley Publishing Co., Reading, MA, USA (1995). 16. P. G. Jones, ‘Computers in Chemical Plant—A Need for Safety Awareness’, in Hazard XI, IChemE Symp. Ser., 124, 289–297, IChemE (Rugby, UK) (1991). 17. N. Gibson, ‘Process Safety—A Subject for Scientific Research’ Trans IChemE, 77, Part B, 149–153 (May, 1999). C G C O N F E R E N C E ADHOC - 99 The Seventh International Symposium on Dioxygen Activation and Homogeneous Catalytic Oxidation (ADHOC-99) was held at York, UK, from 19–23 July 1999. At the meeting, attended by both chemists and biochemists, progress was reported towards the ideal homogeneous oxidation catalyst—one with high selectivity, high stability, and low environmental cost. Biochemists gave several presentations on the mode of action of soluble and membrane- bound methane monooxygenase, which catalyses the dioxygen oxidation of methane to methanol. Such biological oxidases, or microorganisms containing them, show excellent selectivity and are being used to produce a variety of chiral organic compounds of commercial values in the pharmaceutical and other industries. Chemists reported on the production of several new homogeneous oxidation catalysts, e.g. soluble manganese complexes for olefin epoxidations; chelating diamine–palladium complexes for oxidation of olefins to ketones (a green version of the Wacker reaction); and soluble titanium- containing silicate cage compounds as analogues of the titanium-containing zeolite TS-1, already widely used for ‘green’ peroxide oxidation. ‘Green’ oxidation (minimum environmental cost) requires the use of hydrogen peroxide or air (or its reactive component dioxygen) as oxidant. The meeting demonstrated that highly selective catalysts for such ‘green’ homogeneous oxidation are being developed, but catalyst stability remains a problem.

ISSN:1463-9262    

DOI:10.1039/a908580g

出版商:RSC    

年代:1999

数据来源: RSC