摘要:

AbstractThe effect of various curing conditions on the amount of water held by pastes with low water/cement ratios was investigated. It was concluded from the results that factors significantly influencing the total water content of a cement paste made with ordinary Portland cement and cured at room temperature are: water/cement ratio, curing medium, curing period and curing history.

ISSN:0021-8871    

DOI:10.1002/jctb.5010190901

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractThe stability relationships of xonotlite, foshagite and hillebrandite relative to kilchoanite and calcio‐chondrodite have been studied under saturated steam pressures at 180° and 250°. Kilchoanite was unstable relative to xonotlite plus hillebrandite at 180°, or to foshagite plus hillebrandite at 250°; calcio‐chondrodite was unstable relative to hillebrandite plus some more lime‐rich phase, possibly Ca(OH)2, at both temperatures. Foshagite was stable relative to xonotlite plus hillebrandite at 250°, but unstable relative to these phas

ISSN:0021-8871    

DOI:10.1002/jctb.5010190902

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractExamples of formation of troublesome deposits containing ellagic acid in the wood pulping process are mentioned. The deposit from one such process in the U.K. has been examined in detail. This paper is mainly devoted to the determination of some physico‐chemical properties of ellagic acid, which are relevant to the study of minimising the formation of the deposit in the wood digester.A specially built apparatus was used for the determination of these properties at 170° (the normal digestion temperature). The ultra‐violet and visible absorption spectra measured at different pH values and temperatures were used to determine a dissociation constant of the acid at 20° which was found to be 11·0. The solubility of the acid was determined at 20°, 90° and 170°.From the changes in absorbance at 250 nm the decomposition was found to consist of two consecutive firstorder reactions, the rate constant of the first reaction being inversely proportional to a fractional power of hydrogen ion concentration.The activation energy was estimated to be 5·5 kcal and was independent o

ISSN:0021-8871    

DOI:10.1002/jctb.5010190903

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractThree precipitated iron Fischer‐Tropsch catalysts of identical chemical composition but prepared from different source materials were studied by gas adsorption. Of the Hofer ‘inducted’ catalysts, the most active one was found to combine greater surface area with a preponderance of narrower pores, compared with the other two. The greater activity was found to be reflected in the ‘a’ factor (Elovich Equation) which was very large. The limitation of the energy of activation as a parameter for the activity of solid heterogeneous catalyst was illustrated in terms of ‘compensation effect’. The complex nature of adsorption kinetics was shown by the anomalous temperature dependence of ‘a’ as well as changes in the slope ofq

ISSN:0021-8871    

DOI:10.1002/jctb.5010190904

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractIsobaric and isothermal vapour‐liquid equilibria have been determined for the binary systems: methylcyclohexane‐n‐butanol and toluene‐n‐butanol at 760 mm Hg total pressure and 90° using a modified Colburn still. The activity coefficients data were satisfactorily tested for their thermodynamic consistency by the method of Herington and a satisfactory correlation was also obtained through Wohl's three‐suffix Margules equations for both conditions of restraint in the case of both systems. Azeotropes were observed for both systems and both conditions

ISSN:0021-8871    

DOI:10.1002/jctb.5010190905

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractThe kinetics of formation of diazacyclopropane in hydrazine manufacture was studied, using a 1‐litre three‐necked flask. The temperature effect agreed with thermodynamic calculations. The effect of variables such as temperature (−10 to 25°), stirrer speed (1000–2000 rev/min), and ammonia/chlorine ratio (10: 19), were investigated. The reaction was found to be first order with respect to chlorine, and the activation energy and frequency factor in the Arrhenius equation were found to be 5816 cal/mole and 195 min−1re

ISSN:0021-8871    

DOI:10.1002/jctb.5010190906

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

摘要:

AbstractThe kinetics of absorption of oxygen by n‐butyraldehyde dissolved in n‐butyric acid, in the range of concentrations up to 3·1 × 10−3gmole/cm3(25 wt.‐%), in the presence of manganese acetate, was studied in stirred cells and a bubble column. It was found that diffusion of oxygen is important. The reaction was found to be first‐order in oxygen and second‐order with respect to the aldehyde. The overall third‐order reaction rate constant was found to be about 4 × 106(cm3/gmole)2sec−1at 20°. The effect of the catalysts, cobaltous acetate and (cobaltous + 4 cupric) acetates, on the specific rates of absorption of oxygen was also studied. Manganese acetate was found to b

ISSN:0021-8871    

DOI:10.1002/jctb.5010190907

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY

ISSN:0021-8871    

DOI:10.1002/jctb.5010190908

出版商:John Wiley&Sons, Ltd    

年代:1969

数据来源: WILEY