Maximizing the catalytic performance of FER zeolite in the methanol-to-hydrocarbon process by manipulating the crystal size and constructing a bifunctional system

Abstract

Although more than 250 different zeolites/zeo-type materials have been discovered to date, the industrial catalyst catalog of the zeolite-catalyzed methanol-to-hydrocarbon (MTH) process is only limited to ZSM-5 (MFI topology with a 10-membered ring (MR)) and SAPO-34 (CHA topology with 8-MR). Herein, the zeolite FER, in principle, could be an attractive alternative as it owns a two-dimensional interconnecting channel system, where a 10-MR channel is perpendicular to the 8-MR channel. However, a shorter lifetime over commercial and literature-reported synthesized FER (avg. 1 hour) is a grave concern. We have strategically integrated material design and catalysis optimization with advanced characterization to improve the catalyst durability of the zeolite FER-catalyzed MTH process. Herein, we report a unique flake-shaped FER (f-FER) zeolite with optimized physicochemical properties that led to a superior lifetime (∼3 hours) to commercial FER (∼1 hour). Upon combining f-FER zeolite with Y₂O₃, an unprecedented catalyst lifespan (∼20 hours) was accomplished with a preferential selectivity for C₄–C₇ hydrocarbons. Minimizing the involvement of formaldehyde during the early stages of the MTH process favors the alkene cycle over the arene cycle, eventually extending the catalyst lifetime.