摘要:

AbstractNatural Australian beach sand ilmenites and their preoxidised derivatives were reduced to metallic iron and titanium oxides by carbon monoxide at temperatures in the range 800–1200 °C. Particular care was taken to maintain a constant driving force for reduction using small samples and high gas flow rates. Over the entire temperature range studied, the natural minerals were found to reduce more rapidly than the corresponding preoxidised materials, although preoxidation was found to improve the extent of metallisation of the product. Heating the natural minerals in an inert atmosphere prior to reduction decreased their reactivities by approximately 70%. It is suggested that at temperatures below about 900 °C the reduction is controlled by the chemical reaction rate, but that a transport‐controlled mechanism gradually takes over as the temperature is increased. At 1000 °C the reduction is apparently controlled by diffusion of carbon monoxide through the external gas film. With increasing temperature above about 1050 °C, when the reaction mass begins to sinter, the reduction rate de

ISSN:0375-9210    

DOI:10.1002/jctb.5020250802

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe thermal decomposition of nickel hydroxides prepared from aqueous nickel chloride solution on addition of alkali under various conditions has been examined by thermogravimetry, differential thermal analysis, X‐ray diffraction study, visible and infrared spectrophotometry, magnetic susceptibility measurement and electron spin resonance spectroscopy. As a result, it is concluded that the thermal decomposition of nickel hydroxide proceeds in the following sequence:\documentclass{article}\pagestyle{empty}\begin{document}$$ Ni(OH)_2 \xrightarrow{{300^ \circ C}}NiO_{1 + x} (x \ll 1;\;distorted\;cubic)\xrightarrow{{500^ \circ C}}NiO(cubic) $$\end{documen

ISSN:0375-9210    

DOI:10.1002/jctb.5020250803

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractAn electrochemical cell was formed by enclosing a commercial catalyst containing cupric chloride supported by γ‐alumina between electrodes of copper and iron. The voltage obtained is a logarithmic function of the vapour pressure of the water sorbed by the support. Voltages of a few hundred millivolts are obtained at relative pressures between 0.1 and 0.8 and temperatures between 25 and 170

ISSN:0375-9210    

DOI:10.1002/jctb.5020250804

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe diffusion coefficients of potassium aluminium sulphate, ferric ammonium sulphate, chromium potassium sulphate and chromium sulphate were determined using the porous disc technique. For all salts studied linear relations were found between the diffusion coefficient and the square root of the salt concentration:\documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{gathered} \text{for potash alum:}\;\text{D}\;\text{ = }\;\text{a}_\text{p} \text{ - 1}\text{.5 } \times \text{ 10}^{\text{ - 4}} \text{ }\sqrt {\text{C}_\text{h} } \hfill \\ \text{for ferric alum:}\;\text{D}\;\text{ = }\;\text{a}_\text{t} \text{ - 1}\text{.4 } \times \text{ 10}^{\text{ - 5}} \text{ }\sqrt {\text{C}_\text{h} } \hfill \\ \text{for chrome alum:}\;\text{D}\;\text{ = }\;\text{a}_\text{c} _\text{s} \text{ - 8}\text{.1 } \times \text{ 10}^{\text{ - 6}} \text{ }\sqrt {\text{C}_\text{h} } \hfill \\ \text{for chromium sulphate:}\;\text{D}\;\text{ = }\;\text{a}_{\text{cs}} \text{ - 2}\text{.4 } \times \text{ 10}^{\text{ - 6}} \text{ }\sqrt \text{C} \hfill \\ \end{gathered} $$\end{document}The effect of temperature on the diffusion coefficient of the salts was studied. The data were found to fit the Arrhenius equation. The activation energies for the diffusion of potash alum, ferric alum, chrome alum and chromium sulphate were found to be 1.8, 7.4, 2.8 and 3.4 kcal/mol respectively.

ISSN:0375-9210    

DOI:10.1002/jctb.5020250805

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractIn continuation of a previous paper some properties of the same type of miscible oil are studied. The subjects considered are: determination of the constantK(which is characteristic of the emulsifier); mixture of two miscible oils; exposure of the miscible oil to the atmosphere; liquids with which miscible oil could not be obtained and, finally, miscible oil containing an insecticide for use in agriculture.

ISSN:0375-9210    

DOI:10.1002/jctb.5020250806

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractA comparative study was made of the vapour phase oxidation of methanol in presence of gold and platinum, using a flow system at temperatures below 500°C. Over gold there is a stoichiometric conversion to formaldehyde and water. In presence of platinum, the reaction is the same up to 200°C, but at higher temperatures other oxidation products appear. Mechanisms are suggested involving interaction between chemisorbed oxygen and methanol fragment

ISSN:0375-9210    

DOI:10.1002/jctb.5020250807

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe ratios of extinction of the short wave(y)and the long wave(x)band in the visible region of the absorption spectra of three reactive dyes on cellophane film and also in aqueous solution, both in the presence and absence of urea, have been measured. Also changes in the ratio with time of exposure were determined. The ratio is found to increase with the concentration of the dye in the fibre and also in aqueous solution. Urea causes disaggregation. The state of aggregation of reactive dyes in cellophane is found to be intermediate between that obtained in a polyester–disperse dye system and nylon or cellulose acetate or cellulose–triacetate–disperse dye s

ISSN:0375-9210    

DOI:10.1002/jctb.5020250808

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

摘要:

AbstractThe effect of diffusional resistances (both inter‐ and intramembrane) on the kinetic behaviour of an immobilised two‐enzyme system carrying out a consecutive sequence of reactionsS → P1→ P2is analysed for the case in which the intrinsic kinetics can be considered to be first order. The method of solution consists in first representing the diffusion–reaction equations in matrix notation and applying the similarity transformation to reduce the equations to a set of uncoupled equations in pseudoconcentrations. The set of uncoupled equations are solved analytically for the appropriate boundary conditions. The solution to the original problem is then recovered by applying the reverse transformation. Two geometries have been treated, the spherical capsule and the flat plate membrane. The diffusional resistances may be described adequately by two dimensionless numbers, the Thiele modulus and modified Sherwood number. The influence of these parameters on the concentration profiles and “effectiveness factors” have been presented graphically. The analysis is also extended to the prediction of the performance of a packed bed e

ISSN:0375-9210    

DOI:10.1002/jctb.5020250809

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY

ISSN:0375-9210    

DOI:10.1002/jctb.5020250801

出版商:John Wiley&Sons, Ltd    

年代:1975

数据来源: WILEY