摘要:

AbstractMuch effort has been devoted world‐wide towards minimizing exposure to radon and thoron daughters in the exploitation of nuclear energy. In this work, the behaviour of radon and thoron daughters after formation from their gas precursors is discussed, together with optimally designed measurement and dosimetry methods for assessing alpha radiation exposure in uranium mines and mills, in buildings and in the environment. The interaction of radon and thoron daughters with aerosol particles, which is very important in determining the fate of the airborne radioactivity, can be described better in terms of activity‐size distributions than by use of the commonly applied concepts of “attached” and “unattached” fractions. Further, the properties of the aerosol‐daughter system are shown to depend upon humidity and the presence of trace gases, which serve as electron sources to neutralize the newly‐formed positive daughters. Finally, the mechanisms of release of radium and radon from ore and soil are discussed. The significance of the various conclusions to practical situation

ISSN:0008-4034    

DOI:10.1002/cjce.5450610102

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

年代:1983

数据来源: WILEY

摘要:

AbstractBy applying the chemical trapping method to the hydrocondensation reaction of carbon monoxide, we propose a reaction scheme with some novel interesting features. In the chemisorption of CO on Ni/SiO2, Ni/Al2O3, Co, Co/Al2O3we detected species bonded both through the C and O ends of the molecule. This chemisorbed CO can be the intermediate of the dissociation of CO or lead to the formation of a formyl species by reaction with hydrogen. The competition of these two reactions can lead to hydrocarbons or to alcohols.

ISSN:0008-4034    

DOI:10.1002/cjce.5450610103

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe larger pore LaY zeolite catalyst resembles homogeneous metal chloride and heterogeneous silica‐alumina acid catalysts since the results are consistent with isomerization being a series of intramolecular 1,2 shifts. On the other hand, isomerization with the smaller pore zeolite, ZSM‐5, is very different and the relative rate constants appear to be influenced by diffusion and/or shape selectivity. Disproportionation is a significant reaction with LaY but not with ZSM‐5 in the temperature range used for the present study. The small amount of trimethylbenzene formed at low conversions using ZSM‐5 is 1,2,4‐trimethylbenzene, also providing evidence of shape selectivity influencing the reaction

ISSN:0008-4034    

DOI:10.1002/cjce.5450610104

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

年代:1983

数据来源: WILEY

摘要:

Abstract2‐Ethyl‐2‐hexenal was hydrogenated over Raney Nickel and nickel boride in a batch slurry reactor. Using Raney Nickel, the reaction went to completion, and the formation of both 2‐ethylhexanal and 2‐ethylhexanol followed zero order kinetics.Using nickel boride, the reaction ceased at the saturated aldehyde, with saturation of the double bond a zero order reaction. Unsaturated alcohol was not detected in any of the reaction

ISSN:0008-4034    

DOI:10.1002/cjce.5450610105

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

年代:1983

数据来源: WILEY

摘要:

AbstractAlkali oxides added to methanol catalysts increase the formation of ethanol,n‐propanol and isobutyl alcohol. This result has been known for many years, yet few quantitative studies have been reported in the literature. Data obtained on a commercial copper‐zinc oxide catalyst promoted with K2CO3are presented and compared with published work. The optimum promoter concentration was about 0.5% by weight. The H2to CO feed ratio was important in determining the higher alcohol selectivity. The rate of production of isobutyl alcohol varied asp H2−0.7p CO2.2while for methanol, ethanol andn‐propanol both exponents were positive and less than 1.6. Decreasing the hydrogen to carbon monoxide ratio from 2 to 0.5 more than doubled the isobutyl alcohol selectivity. Chain growth schemes predicting the higher alcohol selectivity are presented and estimates of the parameter

ISSN:0008-4034    

DOI:10.1002/cjce.5450610106

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

年代:1983

数据来源: WILEY

摘要:

AbstractA computational study is reported of the behaviour of three catalytic reaction models containing conventional adsorption, desorption, and surface reaction steps under conditions of forced composition cycling in a mixed reactor. The models contained varying degrees of non‐linearity. With long cycle periods, the time‐average rate of reaction asymptotically approached the quasi‐steady state. Time‐average rate behaviour was found to be bounded by the asymptotes of quasi‐steady state rate under slow cycling, and the relaxed steady state under rapid cycling. It is concluded that the approach used until now to model catalytic reactions is very likely inadequate to describe the dynamics of forced cyclic operation observed in a number of experiment

ISSN:0008-4034    

DOI:10.1002/cjce.5450610107

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe residence time distribution (RTD) for diffusion‐free laminar helical flow of non‐Newtonian fluids has been numerically computed for values of the power‐law index from 0.2 to 2.0. Experimental verification is also provided. Excellent agreement is also shown with independently calculated RTD's appearing in the liter

ISSN:0008-4034    

DOI:10.1002/cjce.5450610108

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

年代:1983

数据来源: WILEY

摘要:

AbstractIn coiled tubes of non‐circular cross‐section the orientation of the cross‐sectional plane with respect to the direction of the centrifugal force has a significant effect on residence time distribution (RTD) which has been recognized for the first time. This aspect has been experimentally investigated in helically coiled tubes of square cross‐section, under the conditions of negligible and significant molecular di

ISSN:0008-4034    

DOI:10.1002/cjce.5450610109

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

年代:1983

数据来源: WILEY

摘要:

AbstractThe published literature on gas mass transfer in three‐phase fluidized beds indicates that most of the research done in the last two decades has been carried out at low superficial velocities and/or volumetric flow rates. These experimental limitations are reflected in the current understanding of these systems. In this investigation, performed at large gas and liquid velocities and flow rates, the behaviour of three‐phase fluidized beds of 0.1, 0.3 and 0.5 cm diameter glass beads has been studied.Computer‐made contour diagrams, obtained from the mapping of the oxygen concentration in the column have proven to be an effective probing technique. These diagrams permit the description of flow patterns and bed hydrodynamic properties otherwise not observable with tracers.The use of concentration and pressure profiles complements the observations made with the contour diagrams. At low gas and liquid velocities the concentration profiles areS‐shaped. AsVgandVlincrease the three absorption zones, observed in thoseS‐shaped profiles, become two zone similar to those observed in bubble columns. The interface between the dense bed and dilute phase is characterized by an unusually high mass transfer

ISSN:0008-4034    

DOI:10.1002/cjce.5450610110

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

年代:1983

数据来源: WILEY

摘要:

AbstractA relationship which is capable of predicting the height of a fluidized bed with the extent of the biomass growth at the surface of the fluidized particles is proposed. The application of this relationship for the determination of one of the biological parameters of waste water treatment is demonstrated.

ISSN:0008-4034    

DOI:10.1002/cjce.5450610111

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

年代:1983

数据来源: WILEY