Propane as alkylating agent for alkylation of benzene on HZSM-5 and Ga-modified HZSM-5 zeolites

Alkylation of benzene with propane has been studied under continuous-flow condition at atmospheric pressure. Ga-modified HZSM-5 zeolites have shown to be very efficient catalysts for alkylation of benzene with propane. Toluene and ethylbenzene are formed as major products and cumene and n-propylbenzene are also produced at low reaction temperatures in small amounts. The product formation pathways on HZSM-5 and Ga-modified HZSM-5 have been discussed and suggest that acid-catalyzed cracking of propane predominates on HZSM-5, leading to the formation of toluene and ethylbenzene. Over Ga-modified HZSM-5, a bifunctional pathway is noted and cracking of propane and propane dehydrogenation are controlled by Lewis (Gax+)/Bronsted (H+) acid sites ratio. The effect of oxidative and reductive treatments on catalytic activity has been studied and shown that the catalytic activity and the selectivity to toluene of the Ga-modified HZSM-5 zeolite catalysts are enhanced after H-2/O-2 treatment due to the increase in gallium dispersion. (C) 2003 Elsevier B.V. All rights reserved.