HZSM-5-doped silica microsphere catalysts for methanol-to-olefins reaction: effect of HZSM5/SiO2 ratio

Abstract The methanol-to-olefins (MTO) process provides a promising non-oil-based route for light olefin production, but conventional HZSM-5 catalysts suffer from coke deposition and rapid deactivation. In this study, HZSM-5 was incorporated into silica microspheres (MS) via a novel microencapsulation strategy specifically designed to enable simultaneous tuning of acidity and porosity, addressing limitations of traditional catalyst modification methods. Catalysts with varying HZSM-5/SiO 2 weight ratios (0, 0.1, 0.25, 0.5) were synthesized and characterized using XRD, BET, DRIFTS, SEM, TEM, TGA, FTIR, and ICP-OES. Among them, 0.25HZSM-MS exhibited a balanced micro-mesoporous structure together with moderate Lewis/Brønsted acidity, achieving 85.6% methanol conversion with 48.7% light olefin selectivity. Remarkably, coke formation was reduced by 77% compared with parent HZSM-5, and activity was maintained over eight regeneration cycles. These findings highlight, for the first time, that this microencapsulation-based control of HZSM-5 dispersion within silica microspheres represents a distinct methodological advance, enabling synergistic tuning of acidity and porosity and offering a durable and selective catalyst for MTO applications.