Michel Niclause

Industrial photochemistry II: influence of the stirring of unstable radical species on the kinetics of long chain photochemical reactions

Abstract The experimental rate of a photochemically initiated long chain reaction seems to be a function of the absorption profile of the light, the mean lifetime of the free radical chain carriers and finally of all the processes of homogenization of the medium. The influence of these different factors is defined theoretically and illustrated with the aid of gas—liquid-type reactions, i.e. photooxidation of heptanal and benzaldehyde and photochlorination of benzyl chloride.

Industrial photochemistry I: measurement of the absorption profile of the light in a photochemical reactor

Abstract Knowledge of the local distribution of the light energy in a photochemical reactor in the presence of an absorbing substance, leading to a reaction of which the rate is of an order different from first order with respect to the absorbed light intensity, is important to calculate the mean rate of reaction and the design of the reactor. We report a simple method for the determination of this profile as a function of the concentration of an absorbing substance and we compare the results obtained with the models of emission which have been published. A semiempirical model accounting for our experimental results is presented.