Reactions of Heptanes, Octanes, and Cycloparaffins over a Palladium-Silica-Alumina Catalyst

Abstract

Summary:Experiments were carried out on the reactions of four heptane isomers, four octane and 60kg/cm2 hydrogen pressure, in order to have a better understanding of the reactions. Reaction products were analyzed by means of a gas chromatographic unit. Reaction rate and selectivity were studied at low conversion levels with the following results:(1) Paraffinic hydrocarbons with higher number of branches were converted faster than did those with lower number of branches;(2) Isomerization reaction of a paraffin molecule to others with the same number of branches were very fast;(3) Hydrocracking reactions were very slow compared with isomerization reactions except for trimethylpentanes;(4) Decyclization reactions of methylcyclopentane and methylcyclohexane were very slow. Discussed were the reaction path and mechanism, and it was suggested that tertiary carbonium ions are more reactive than secondary ones and far more reactive than primary carbonium ions because of the higher rate of adsorption of olefins to form tertiary carbonium ions, the higher concentration of tertiary carbonium ions on acidic sites, and the higher rate of desorption of the tertiary carbonium ions.

Platinum/Alumina Catalysts in Reforming Methylcyclopentane

“…These observations are nearly identical with those obtained in the present study. The high percentage of nHx was also observed on a thiophene poisoned Pd catalyst (Iijima et al, 1970). Both in their work and the work by Smith et al (1971) (referred to below) one or both of the reaction paths fpr nHx formation on a acidic site shown in Figure 4 are presented without further comments.…”