ChemInform Abstract: The Effect of Temperature on the Product Distribution and Kinetics of Reactions of n‐Hexadecane on HY Zeolite

Abstract

Abstract Reactions of n -hexadecane on HY zeolite have been studied at 300 and 400 °C. At both temperatures, initial cracking products, as well as initial products of skeletal isomerization and coke formation, were observed in the range C 2 C 10 . At 300 °C paraffins were the dominant initial product, whereas olefins were dominant at 400 °C. This can be explained as being the result of more extensive hydrogen transfer at the lower temperature, resulting in a more unsaturated coke and more gas phase paraffins. Aromatics were formed by initial processes at both temperatures with similar selectivity. Reports that hydrogen is irreversibly lost from active sites associated with the catalyst framework, to produce saturated hydrocarbons, were not confirmed. Kinetic parameters were obtained at both 300 and 400 °C and their magnitudes are found to reflect changes in product distribution at these two temperatures. The fact that, over the range of conversions studied, product olefin species are present in much greater abundance at the higher temperature gives rise to more pronounced competitive inhibition at 400 °C than at 300 °C. Catalyst deactivation was found to occur much more rapidly at the lower temperature. This is related to the nature of the coke deposited. It appears that coke is more deactivating when it is more dehydrogenated.