摘要:

AbstractEleven representative polyethyleneglycol (25322–68–3) catalytic dehydration reactions have been studied in the liquid phase at atmospheric pressure. The aim of this research is to build a kinetic model representative of the polyethyleneglycol dehydration process. Three types of reaction take place simultaneously in the process: cyclisation, condensation and alcoholysis. Activation energies and frequency factors are given, and the relationships between kinetic parameters and chain length of reactants and products are discussed according to the reaction t

ISSN:0264-3413    

DOI:10.1002/jctb.5040350602

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThe phase transfer catalysed esterification of phenols with aliphatic acid chlorides was carried out in a basic bi‐phasic aqueous‐organic medium. Unhindered phenols, i.e. having at least one freeorthoposition, gave good to quantitative yields of ester whileorthodisubstituted phenols gave low to moderate yields of ester only with the higher, less water soluble acyl homologues (≧C5). Phenol‐free ester was easily obtained by simple phase separation and evaporation of the organi

ISSN:0264-3413    

DOI:10.1002/jctb.5040350603

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractA beta‐silicon carbide powder with a surface area of 30m2g−land a mean particle size of<1μm was produced from the thermal conversion of silicon resin in an atmosphere of hydrogen. The amount of product increased with increasing iron content (0–2.1 wt%) and firing temperature (1200–1500°C). Chemical analysis, X‐ray diffraction and i.r. absorption spectrometry were used to follow the conversi

ISSN:0264-3413    

DOI:10.1002/jctb.5040350604

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThe production of deposits from oil on various materials has been studied under conditions pertinent to the ring zone of a diesel engine piston. Deposition is found to occur only as a result of oxidation, and metal catalysed free radical reactions in the liquid phase appear to be responsible for the problem. Metal species removed from the surface are the most active promoters and these may be deactivated by heavy deposition (encapsulation) or by the addition of deactivating complexing agents.

ISSN:0264-3413    

DOI:10.1002/jctb.5040350605

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractA silica gel characterised as predominently microporous, with the remaining pores of limited dimensions which do not permit capillary condensation, is modified with aqueous solutions of acetic acid, glycine and β‐alanine. The modified samples are investigated and compared with a water soaked sample by means of differential thermal analysis, thermogravimetry and i.r. spectroscopy. Textural measurements are also carried out on the parent samples and those produced in the temperature range 110–600°C. Acetic acid is both physically and chemically adsorbed; a surface ester is formed. Both amino acids are physically adsorbed but no chemical interaction has been detected. Glycine and β‐alanine decompose differently when adsorbed on to the silica surface than when in the pure state. The specific surface area decreases upon modification, reaching half the value of the pure silica for the β‐alanine modified sample. Pore structure analysis, shows that the microporous nature of the modified samples decreases in the modifier order acetic acid

ISSN:0264-3413    

DOI:10.1002/jctb.5040350606

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractThe analytical characterisation and production of wool wax fromAkkaramanandMorkaramansheep in the East Anatolien region of Turkey have been investigated. It was shown that the analytical characteristics ofAkkaramanandMorkaramanwool waxes differ only slightly from other wool waxes. Therefore, from a quality point of view, wool waxes obtained from this work can be used for the same purposes as wool waxes produced from different varieties of sheep.

ISSN:0264-3413    

DOI:10.1002/jctb.5040350607

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractA new simplified VLE model of the CO2‐NH3‐H2O system under conditions of the distillation and absorption steps of the recycle urea process is developed. For the gaseous phase the virial state equation is adopted and the component activity coefficients are approximated by a simple linear expression. The resulting equations for the equilibrium constants of the physical and chemical equilibria are fitted to experimental values (in the literature) within the temperature range of 307 to 414 K and within the pressure range of 2 to 40 bar. Tests of the model on the experimental data are presented as well as the comparisons with other published simplified VLE models of the sys

ISSN:0264-3413    

DOI:10.1002/jctb.5040350608

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractPrevious studies proved that the slag content of the blast furnace slag‐Portland cement mix could be increased, while retaining the engineering properties of the produced slag cement pastes within the normal range and increasing the fineness of the mix. The corrosion behaviour of reinforcing steel embedded in the cement pastes giving the optimum mechanical properties was studied using the galvanostatic polarisation technique. The most corrosion‐resistant mix has been determined. The effect of adding CaCl2to a paste of this mix on the corrosion behaviour of embedded reinforcing steel has been investigated. For the purpose of comparison, anodic polarisation tests were carried out using pastes having the composition of the most corrosion‐resistant mix but at the Blaine area of the ordinary slag cement. Portland and normal slag cements were also tested. The threshold concentration of CaCl2, below which breakdown of steel passivity did not occur, has been determined. The results of this study might have practical implications in the

ISSN:0264-3413    

DOI:10.1002/jctb.5040350609

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

摘要:

AbstractMethanol and methanol containing small quantities of nitrosobenzene,p‐benzoquinone andp‐cresol were passed at a liquid hourly space velocity of 1.0 h−1over the microporous aluminosilicate catalyst HTDZ‐48 at temperatures in the range 250–450°C. In each case the methanol was converted to hydrocarbons. The presence of nitrosobenzene caused a reduction in the methanol conversion,p‐benzoquinone had little effect andp‐cresol caused an increase in metha

ISSN:0264-3413    

DOI:10.1002/jctb.5040350610

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY

ISSN:0264-3413    

DOI:10.1002/jctb.5040350601

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1985

数据来源: WILEY