ChemInform Abstract: Cracking and Isomerization of Hydrocarbons with Combinations of HY and HZSM-5-Zeolites

Catalytic reactions of n-octane on sequential cambinatians of HY and HZSM-5, as well as on random mixtures of the zeolites, have been examined. Theoretical product distributions have been calculated for reactions on these catalyst combinations by assuming relative contributions based on the individual product distributions as well as the conversions on the individual components. Effects due to interactions of products of one catalyst with the other in a binary combination can be identified by comparing theoretical and observed product distributions. Predicted values from this approach provide a good approximation when considering the product distributions in terms of total hydrocarbons formed at each carbon number. Significant differences are found between observed and predicted values in the relative proportion of paraffins and olefins at a particular carbon number, and also in the ratios of branched to linear paraffin isomers. Reaction processes attributable for these deviations have been identified as hydrogen transfer processes, particularly on HY, and paraffin isomerization on HZSM-5.