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-dealumination (Si/Al = 25, 50, 100, 200, ∞), has been studied. 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 Brønsted acidic sites remain intact in the micropores, as revealed by IR and 1H MAS-NMR. These materials can be regarded as bifunctional catalysts, containing isolated Ga sites and Brønsted sites in proximity, suitable for propane aromatization. Catalytic investigations show high activity and selectivity toward aromatics, particularly for low Si/Al ratios.