摘要:

AbstractAn alternative one‐pot synthesis of N‐benzyl‐N‐ethylaniline, an important dyestuff intermediate, has been achieved by reductive alkylation of easily available aniline as starting material. The reaction has been extended to the preparation of other substituted N‐benzyl‐N‐ethylanilines. New insights into the mechanism of the reactions have been obtained. A more economical two‐stage process involving reductive ethylation of N‐benzylaniline

ISSN:0268-2575    

DOI:10.1002/jctb.280510302

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractVarious adsorption isotherms were matched to the interfacial tension data in the N‐8‐quinolyl‐p‐dodecylbenzenesulphonamide‐toluene‐water system and used to compute the surface excess isotherms and to predict the reaction orders with respect to extractant for various versions of the interfacial mechanism of copper extraction. Comparison of these reaction orders with those determined experimentally shows that the reaction rate can be limited by the formation of the stable 2:1 complex in the reaction of intermediate 1:1 complex with the sulphonamide molecule both adsorbed at the interface and present in the aqueous film near th

ISSN:0268-2575    

DOI:10.1002/jctb.280510303

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractA mechanic study is reported, which deal with the kinetic aspects of yttrium extraction from HAc‐NaAc‐EDTA media, using three acidic phosphorus extractants (HL), di(2‐ethylhexyl)phosphoric acid (HDEHP), 2‐ethylhexylphosphonic acid mono‐2‐ethylhexyl ester (HEH[EHP]) and di(2,2,4‐trimethylpentyl)phosphinic acid(H[DTMPP]) in n‐octane solution. The initial rates of extraction for these three systems were determined under conditions of energetic stirring or mixing of the two phases. The rate data were correlated as a function of the concentration of the relevant species. From the rate equationsand the interfacial characteristics, the heterogeneous chemical reactionwas established as the rate‐determining step of the overall reaction for the three extractants studied. A mechanism has been proposed for this reaction. The order of the extraction rate was found to be HDEHP>HEH[EHP]>H[DTMPP], and is related to the number of CP bonds

ISSN:0268-2575    

DOI:10.1002/jctb.280510304

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractA theoretical model has been developed for heat transfer in bubble column and airlift bioreactors, which is applicable for Newtonian and non‐Newtonian fermentation media. The proposed model is based on a similarity between heat transfer in gas‐sparged pneumatic reactors and turbulent natural convection. The applicability of the proposed model was discussed using a wide range of experimental data, and good agreement was obtai

ISSN:0268-2575    

DOI:10.1002/jctb.280510305

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe catalyst deactivation kinetics for the dehydrogenation of methylcyclohexane were studied with Pt‐, PtRe‐, and presulfided Presulfided PtRe‐Al2O3Catalysts in a fixed‐bed differential reactor. The kinetic analysis was made based on a Langmuir‐Hinshelwood model assuming that the dehydrogenation of methylcyclohexene into methylcyclohexadiene was the rate‐controlling step for the main reaction, and the polymerization of adjacently adsorbed methylcyclohexadiene as coke precursor molecules was the rate‐controlling step for the deactivation reaction. The experimental data for the three catalysts at varying partial pressures of methylcyclohexane and hydrogen were well correlated by the hyperbolic deactivation function derived. The number of active sites involved in the rate‐controlling step of the deactivation was evaluated to be 2.7 in average. The enhanced activity maintenance by the addition of Re as well as sulfur was attributed to a reduction in the concentration of multiple sites occupied by coke precursors adjacently adsorbed, leading to a decrease in the rate constant of the deacti

ISSN:0268-2575    

DOI:10.1002/jctb.280510306

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe continuous separation of a multicomponent feedstock on a rotating annular chromatograph is described. The annulus width was 12 mm, diameter 300 mm and height 1400 mm. The annulus was packed with a 420 micron ion‐exchange resin in the sodium form. The feedstock separated was beet molasses which is the final syrup spun off after repeated crystallisations in the extraction of sugar. Two basic mechanisms were in operation to separate sucrose from impurities: ion exclusion and molecular sieving. A statistical approach was made to set up an experimental programme and analyse the results. Four factors were studied: feed flowrate, feed concentration, annulus rotation rate and eluent rate. Two of these, namely feed rate and eluent rate, significantly affected the response. The response was the separation achieved using the annular chromatograph between the sucrose and non‐sucrose solids. A further series of experiments demonstrated the practical considerations to be made when separating beet molasses. A crystallisable product sucrose rate of 207 gh−1was ach

ISSN:0268-2575    

DOI:10.1002/jctb.280510307

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractThe extraction of oil from oil reservoirs beneath the North Sea has stimulated an immense popular interest in oil exploration and production. The mass media cover many of the sensational aspects of the industry but the mechanisms of the production of oil from the reservoir are not often mentioned. This is partly because the reservoir is a huge heterogeneous volume hidden underground, but also because some background in science is required. The mechanisms of oil recovery depend to a great extent on what happens at the interface between the displaced and displacing fluids at the pore scale (μm) and the reservoir scale (km). Oil is left unrecovered in areas of the reservoir where the displacing fluid has not passed (by‐passed zones–sweep efficiency) and as droplets trapped in the pores in areas where displacement has occurred (microscopic residual oil–pore displacement efficiency). The physics at the interfaces, including the interplay between capillary, (interfacial tension, wettability), viscous and gravity forces is fundamental to an understanding of the retention of this residual oil (a common reservoir average estimate is over 60%) trapped by the capillary forces or by‐passed by the displacing gas or liquid due to inhomogeneity of the reservoir. The alteration of the balance of these forces is the key to enhancing the oil recovery, either by sweeping new areas of the reservoir or recovering some of the microscopically trapped oil.This article is written to provide some of the background to oil production in the context of enhanced oil recovery (EOR). It firstly covers oil recovery that is normally practised, then describes the EOR techniques currently under active development and finally discusses some of the problems that research must overcome before EOR can be successfully implemented with co

ISSN:0268-2575    

DOI:10.1002/jctb.280510308

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractRelationships between the removal efficiency and the hydraulic regimes of trickling filters were investigated. At low flow rates, where break‐up of liquid jets occurs and drops form, completely mixed conditions prevail. For large hydraulic loadings effluent concentrations were calculated by means of a dispersed plug flow model. The ranges of validity of these models were studied theoretically. The effects of drop formation and breakage of liquid jets on the substrate utilization are expressed in terms of hydraulic and physical properties of the media and liqui

ISSN:0268-2575    

DOI:10.1002/jctb.280510309

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractIn the analysis of organochlorines such as polychlorinated biphenyls (PCBs) and polychlorinated naphthalenes (PCNs), levels of, for example, PCB concentration are often expressed as a ‘total PCB’ value, using a straight GC pattern‐matching technique with electron capture detection. Such methods provide little information about the identity of the individual components. In the present study, preliminary investigations using dechlorination with a NiCl2/NaBH4catalyst indicated that the technique offered a comprehensive method for the analysis of PCBs and PCNs, as well as a method of detoxification of the ‘priority pollutants’ . This paper reports the use of capillary column GC‐MS with an ion trap detector (ITDTM) for the analysis of a number of PCBs and PCNs, including the commercially produced Aroclor 1254 and 1221, employing this dechlorinatio

ISSN:0268-2575    

DOI:10.1002/jctb.280510310

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY

摘要:

AbstractIn the first paper on the dechlorination of organochlorine compounds, results were reported for polychlorinated biphenyls and polychlorinated naphthalenes, using the Ni2B in‐situ catalytic dechlorination technique. In the present study, the work has been extended to the dechlorination and detoxification of some chlorinated polycyclic hydrocarbons belonging to a cyclodiene insecticide group (dieldrin, aldrin and endrin). In addition, a cage‐structured polychlorinated insecticide, ‘mirex’, has also been investigated. During the dechlorination process, intermediates were detected by GC/MS and identified by their characteristic mass fragments and retention

ISSN:0268-2575    

DOI:10.1002/jctb.280510311

出版商:John Wiley&Sons, Ltd.    

年代:1991

数据来源: WILEY