摘要:

AbstractFrom a review of existing studies on the oxidation of hydrocarbons, the relationship between structure and ease of oxidation at low temperatures appears to be quite anomalous, compared with most other hydrocarbon reactions.Recent experimental results indicate that the anomalous relationship between structure and reactivity is associated particularly with the fate of the energy‐rich peroxide radical, R·*, whose formation and reaction are generally writtenFactors which may favour reaction (b) include a low energy of transfer of hydrogen from RH to RO2·, and a high energy content made available for activation by vibration coupling within the hydrocarbon molecule. Collisions of RO2· with hydrogen or mercury hinder reaction (b). In addition to possible vibrational‐energy activation it is suggested that RO2· may exist in more than one electronic state, with different energy c

ISSN:0021-8871    

DOI:10.1002/jctb.5010030502

出版商:John Wiley&Sons, Ltd    

年代:1953

数据来源: WILEY

摘要:

AbstractFrom theoretical considerations, an expression has been derived for the instantaneous temperature distribution in an ion‐exchange column. The theory predicts a ‘hot spot’ which will move along the tube with uniform velocity, and whose peak temperature will attain a steady value as it passes along the tube. With increasing concentration of regenerant this steady value increases; the time required to reach this steady value also increases, until at a critical concentration the temperature continues to increase indefinitely. At concentrations exceeding this critical value, the steady value will fall, so that a low maximum temperature is found for both low and high concentrations.Experiments with varying regenerant concentrations confirmed these results regarding the behaviour of the steady value, and agreement between the theoretical and experimental values of the peak velocity was within the limits of experimental error, in the range of concentrations likely in practice.Owing to experimental difficulties in determining the fraction void and in interpreting bed‐volume figures and the effects of the swelling that occurs with many resins, quantitative prediction of maximum temperatures and of velocities may not be satisfactory until more information about the physical behaviour of ion‐exchangers is

ISSN:0021-8871    

DOI:10.1002/jctb.5010030503

出版商:John Wiley&Sons, Ltd    

年代:1953

数据来源: WILEY

摘要:

AbstractThe production of formaldehyde from methanol, either by thermal decomposition, by catalytic oxidation or by a combination of the two, is treated as an exercise in chemical thermodynamics. Simple dehydrogenation of methanol does not appear attractive because it requires temperatures which tend to produce decomposition of the formaldehyde as it is formed. Oxidation of methanol to formaldehyde and steam requires the agency of a catalyst which is active in the region of 300°, the ideal working mixture for an insulated catalyst containing roughly 5 1/2 to 8% of methanol in air. The composite process, in which dehydrogenation and oxidation occur simultaneously, offers certain advantages, and may be expected to give maximum efficiency in the range 500–700°, corresponding to methanol/air mixtures containing 45 to 37% of methanol. Addition of steam to the reacting mixture lowers the catalyst temperature and modifies the product composition accordingly. Rapid cooling of the products to about 300° is essential to avoid regeneration of methanol and decomposition of formaldehyde. An interesting feature is that the straight oxidation‐process operates with mixtures of methanol and air at or just below the lower inflammability limit, whereas the composite process requires mixtures at or above the upper inflammability

ISSN:0021-8871    

DOI:10.1002/jctb.5010030504

出版商:John Wiley&Sons, Ltd    

年代:1953

数据来源: WILEY

摘要:

AbstractChanges in surface structure brought about by removal of the high‐solubility layer from crystallinequartz and fused‐silica (Vitreosil) dusts by 40% hydrofluoric acid, and from Lochaline‐sand dust by a borate buffer (pH 7·5), are studied by electron‐optical methods. The accompanying changes in electron‐diffraction pattern show that the original surface‐layer is amorphous (estimated mean thickness about 0·03–0·06 μ); for quartz and Lochaline‐sand dusts there is some evidence of an intermediate layer of very minute crystallites between the amorphous‐layer and

ISSN:0021-8871    

DOI:10.1002/jctb.5010030505

出版商:John Wiley&Sons, Ltd    

年代:1953

数据来源: WILEY

摘要:

AbstractIt is shown that the incineration period for determining sulphur in coal can be reduced, in a well ventilated muffle, to I hour at 775–800°, for a 1‐g. sample with 4 g. of Eschka mixture. The same time can be used for high sulphur contents with 0° i‐g. samples. The essential feature in obtaining complete precipitation of the sulphate ion is to ensure adequate excess of barium chloride of which 10 ml. of 10% BaCl2,2H2O is adequate for sulphur up to 0·08 g., a similar excess being obtained by using 10 ml. with 0·1‐g. samples for sulphur contents of 8–80%. For sulphur contents higher than 80%, 0·1–g. samples, with 70% excess of barium chloride, should be used.It is shown that the barium sulphate precipitate is most quickly and accurately determined by igniting the wet filter‐paper in a well ventilated muffle, with precautions to a

ISSN:0021-8871    

DOI:10.1002/jctb.5010030506

出版商:John Wiley&Sons, Ltd    

年代:1953

数据来源: WILEY

摘要:

AbstractA new method is described for converting manganese dioxide into manganous sulphate by treating manganese wad with gaseous sulphur dioxide. The reaction proceeds over a wide range of temperatures and sulphur dioxide partial pressures, but above 400° the reaction between iron and sulphur dioxide becomes appreciable. At lower temperatures the utilization of sulphur dioxide for sulphate ion formation approaches 100%, and sulphate ion corresponds stoicheiometrically to manganous ion. At furnace temperatures of 300–400°, using a gaseous reactant containing 15% of sulphur dioxide, 60–70% of the manganese in the wad is converted into soluble sulphate, the limiting factor being the decreasing concentration of manganese dioxide as reaction proceeds. For higher conversions, the reaction temperature may be increased, a richer gas may be used, or the sulphate first formed may be removed by leaching and the residue resubmitted to reaction with sulphur di

ISSN:0021-8871    

DOI:10.1002/jctb.5010030507

出版商:John Wiley&Sons, Ltd    

年代:1953

数据来源: WILEY

摘要:

AbstractMolecular or milli‐pore filter membranes have been used for a number of years in Europe. The Goetz type, recently introduced in America, not only retains all micro‐organisms from a large volume of liquid but also can be placed in contact with an absorbent pad soaked with concentrated nutrient solution; this solution passes through the pores of the membrane to the bacteria deposited on its surface, so that they can be cultivatedin situ.The work described below is a preliminary survey to assess the possibility of applying membrane‐filter technique to media and methods commonly used in Britain for the bacteriological examination of water. The chief advantages of the technique are concentration of micro‐organisms, removal of inhibitory substances and saving in glassware and in media preparation.Further investigations proposed include the examination of a series of samples, the development of a procedure for achieving a rapid result and the isolation of pathogenic organisms from sewage effluents and polluted

ISSN:0021-8871    

DOI:10.1002/jctb.5010030508

出版商:John Wiley&Sons, Ltd    

年代:1953

数据来源: WILEY

ISSN:0021-8871    

DOI:10.1002/jctb.5010030509

出版商:John Wiley&Sons, Ltd    

年代:1953

数据来源: WILEY

ISSN:0021-8871    

DOI:10.1002/jctb.5010030501

出版商:John Wiley&Sons, Ltd    

年代:1953

数据来源: WILEY