Reaction of butanes an Na,H-Y zeolites and H-mordenites

The reaction chemistry for the conversion of isobutane and n-butane on H-mordenites was compared with that on Na,H-Y zeolites in continuous flow experiments. The close resemblance of the product distribution as a function of conversion suggests that identical mechanism for conversion is effective on both types of zeolites, Hydrogen and methane from isobutane and in addition ethane and ethylene from n-butane were expected to be formed in chain initiation processes, while propene and butenes were expected to be formed in chain termination processes. The major products, alkanes, are produced in chain carrying hydride and methyl transfer, A rate of initiation approximately 10-fold higher than with mordenites having stronger Bronsted acid sites is required to reach identical conversion with Y-zeolites. The yield of individual products on zeolites with identical structure and at identical temperature was almost independent of the Si/Al ratio or the Na+ content of zeolites but depended on the conversion; at identical conversion the chain length on zeolites with different activity was similar. (C) 1996 Academic Press, Inc.