KINETIC MODELING OF PROPANE AROMATIZATION REACTION OVER HZSM-5 AND GAHZSM-5

A detailed kinetic model for a propane aromatization reaction over HZS M-5 and GaHZSM-5 is developed. Kinetic modeling results show that prop ane transformation over HZSM-5 occurs via protolytic cracking and hydr ogen transfer routes. The contributions of both routes in propane conv ersion are established. Rate constants of propane transformation steps are found to be at least 1000 times lower than the rate constants of diene formation steps, which, in turn, are the slowest among the acid- catalyzed olefin aromatization steps. Gallium introduced into ZSM-5 ca talyst is active in dehydrogenation of propane into propene, of olefin s into dienes, and of naphthenes into aromatics. At the same time, gal lium species catalyze propane transformation into methane and ethene h ydrogenation into ethane. Both latter reactions appear to be the main reasons for the limit to aromatics selectivity over GaHZSM-5 catalysts .