摘要:

AbstractThe theory of continuous crystallisation (especially of sucrose) in crystallisers connected in series, in which a suspension of growing crystals is fed forward through the system without backmixing, is presented, and the calculation of the minimum coefficient of variation that can be attained under stated conditions is described. Two cases specifically considered are: (1) stirred reactors of equal mean residence times connected in series, and (2) tubular reactors in which the residence time distribution is given by a Gaussian error function. Reduction of coefficients of variation either by connecting reactors in series or by extending a tubular reactor in the axial direction is considered. Series connexion is always superior to extension because it prevents backmixing at the points of connexion.

ISSN:0021-8871    

DOI:10.1002/jctb.5010201001

出版商:John Wiley&Sons, Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractPublished data on the sizes of small molecules measured by gel permeation chromatography are reconsidered after subjecting them to a recalculation procedure which gives molecular sizes in consistent units. Almost half the results are rejected as being unreliable.A set of molar volume values for n‐alkanes is recommended as a standard which should be used to calibrate gel permeation chromatographs irrespective of operating conditions.Molar volumes of some simple gases are give

ISSN:0021-8871    

DOI:10.1002/jctb.5010201002

出版商:John Wiley&Sons, Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe non‐volatile component of a brake fluid can be identified by comparing the gel permeation chromatogram of the fluid with those of a range of possible non‐volatile compone

ISSN:0021-8871    

DOI:10.1002/jctb.5010201003

出版商:John Wiley&Sons, Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe catalytic hydrogenation of benzene was investigated over a supported nickel catalyst in a continuous stirred‐vessel reactor between 260° and 450°F at atmospheric pressure. The effects of temperature, ratio of hydrogen to benzene and total feed rate (or contact time) on the conversion of benzene and yield of cyclohexane were determined.The use of the stirred reactor helped to eliminate mass transfer limitations. The investigation was carried out using surface‐coated catalysts in order to eliminate pore diffusion which might otherwise mask the actual kinetics.Studies of the mixing characteristics of the reactor were carried out under both reacting and non‐reacting conditions, by following conversion as a function of stirrer speed and by a tracer (pulse) technique, respectively.The kinetic data were analysed to determine the most probable model to represent the reaction. The Houghen–Watson type analysis was carried out using non‐linear least squares instead of the usual linear one. The model that satisfactorily correlated the data over the entire temperature range describes the rate‐controlling step as the surface reaction between adsorbed hydrogen and adsorbed benzene, the hydrogen addition being simultaneous. The following Hougen–Watson type equation was proposed:r= keKH3KBPH3PB/(1+KHPH+KBPB+KCPC)4.The constants in this rate equation were expressed as a function

ISSN:0021-8871    

DOI:10.1002/jctb.5010201004

出版商:John Wiley&Sons, Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe rate of reduction of chromium(VI) oxide in acetic acid–acetic anhydride solution by a number of cyclo‐paraffins has been measured. The values obtained agree with those calculated from the proposed expression (Rnp+R'ns+R''nt)/(np+ns+nt), based on the Chambers&Ubbelohde equation, with some deviations.Trans‐1,2‐dimethylcyclohexane oxidised at a rate slower than expected whilst cyclopentane and methylcyclopentane showed a rate higher than the calculated value. A tentative explanation is given based on confornational analysis and strain energy conside

ISSN:0021-8871    

DOI:10.1002/jctb.5010201005

出版商:John Wiley&Sons, Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractThe oxidation of butadiene to crotonaldehyde has been investigated using an aqueous catalyst solution containing palladium chloride–cupric chloride in dilute hydrochloric acid. Unlike the oxidation of ethylene, propylene, etc., this oxidation was found to be a zero‐order reaction with respect to butadiene. The effects of temperature and the concentration of Pd2+, Cu2+, Cl−and H+ions on the reaction rate were studied. The order of reaction with respect to Cl−and H+ions in this case (approximately 1.5 and −0.25, respectively) is different from that observed in the case of lowe

ISSN:0021-8871    

DOI:10.1002/jctb.5010201006

出版商:John Wiley&Sons, Ltd    

年代:1970

数据来源: WILEY

摘要:

AbstractKinetic studies were made of the oxidation of carbon monoxide to carbon dioxide in a fixed bed of ferric oxide catalyst. It was found that the rate of oxidation,R, is given by the equation R = k1k1pco/1+(k1/k2)pco where k1, k1and k2are constants andpco is the partial pressure of carbon monoxide. This rate law is similar to that derived for the same reaction on a vanadium oxide catalyst. The rate equation reduces to first order for carbon monoxide concentrations<1 %.

ISSN:0021-8871    

DOI:10.1002/jctb.5010201007

出版商:John Wiley&Sons, Ltd    

年代:1970

数据来源: WILEY