THE ACIDITY AND CATALYTIC BEHAVIOR OF MG-ZSM-5 PREPARED VIA A SOLID-STATE REACTION

A series of Mg-ZSM-5 zeolite catalysts with different content of magne sium were prepared via a solid-state reaction of HZSM-5 with magnesium chloride at 327 degrees C. X-ray determinations demonstrated that the structure and crystallinity of the catalysts were not changed as comp ared with HZSM-5 zeolite. The acidity of the catalysts was characteriz ed by temperature programmed desorption of ammonia and infrared spectr a of pyridine adsorption. The studies indicated that their Bronsted ac id sites decreased and Lewis acid sites slightly increased with increa sing magnesium amount in the zeolites. The catalytic properties of the catalysts have been examined by choosing the alkylation of toluene wi th methanol as probe reaction. The results showed that the modified ze olite catalysts significantly improved the initial activity and lifeti me. Para-selectivity also increases to a level of 80-90%. These result s indicate that the solid-state reaction is an effective and convenien t route for modification of the zeolite.