Design of plate-like H[Ga]MFI zeolite catalysts for high-performance methanol-to-propylene reaction

Constructing plate-like zeolites with the controllable acidity represents an efficient strategy to promote their catalytic performance in methanol-to-olefins conversion. Herein, the plate-like H[Al/Ga]MFI zeolites with the similar crystal morphology but controllable acidity have been prepared via a fluoride-assisted low-temperature crystallization approach. The acidic properties of the plate-like zeolites are determined by NH3-TPD and probe-assisted 1H and 31P MAS NMR spectroscopy. The impact of acidity including the strength and density of the plate-like H[Al/Ga]MFI on the dual-cycle mechanism and the corresponding catalytic performance in the methanol-to-propylene conversion is subsequently confirmed. Reducing the acid strength and density can efficiently suppress the aromatic-based cycle, and thus hinder the accumulation of the polycyclic aromatics. The plate-like H[Ga]MFI zeolites with weak acid strength and most suitable acid density can well balance the dual-cycle mechanism, thereby achieving high propylene selectivity and long catalyst lifetime simultaneously.