Catalytic cracking of decalin isomers over REHY-zeolites with different crystallite sizes

Abstract

Cracking of a mixture of cis/trans-decalin was carried out over small crystallite rare-earth containing Y zeolites (REHY). Results showed that, although the reactivity of cis-decalin is much higher than that of trans-decalin, no influence of crystallite size was detected, as an indication that differences in reactivity should be attributed to differences in the structure of the reacting molecules, and not to the characteristics of the zeolite. In fact, deuterium exchange between deuterated HY zeolite and decalin revealed that cis-decalin is much more reactive than its trans-isomer. Trans-decalin, according to its structure minimized by molecular mechanic force field MM2, presents a more hindered tertiary CH bond, therefore making protonation and the formation of adsorbed carbocations difficult.