Ga(iBu)3 supported on meso H-ZSM-5: Effect of Si/Al ratio on the activity and selectivity in propane aromatization

Abstract

The grafting of Ga(iBu)3 on a series of meso-H-ZSM5, prepared by desilication-dealuminiation(Si/Al=25,50,100,200,∞) has been studied. The materials were characterized by IR, solid- state NMR, BET, ICP and EXAFS. Ga(iBu)3 reacts selectively with silanol groups, yielding a monopodal surface species in the mesopores. Importantly, the Bronsted acidic sites remain intact in the micropores, as IR and 1H MAS-NMR revealed. These materials can be regarded as bifunctional catalysts, containing isolated Ga sites and Bronsted sites in proximity, suitable for propane aromatization. Catalytic investigations show high activity and selectivity toward aromatics, toward aromatics, particularly for low Si/Al ratios.