Activity of different structural types of zeolites in oligomerization of C3-C4 olefins

1. On zeolites of the L, mordenite erionite, Y, and Pentasil types at 50-200°C, isobutylene undergoes selective dimerisation and trimerization, whereas oligomerization of propylene on these zeolites is observed only above 200°C and is accompanied by isomerization, cracking, and other conversions of the oligomers that are formed. 2. The highest activity in isobutylene oligomerization is manifested by L zeolite, the lowest activity by the Pentasil type zeolite, which also loses its stability of operation (characteristic for Pentasils) when the molar rate of olefin feed is increased. 3. On narrow-pore zeolites (Pentasil and erionite) below 20.0°C, isobutylene is selectively dimerized and trimerized mainly on active centers localized on the outer surface of the crystallites since the zeolite channels are blocked by strongly chemisorbed oligomers.