Methanol Aromatization over Mg–P-Modified [Zn,Al]ZSM-5 Zeolites for Efficient Coproduction of <i>para</i>-Xylene and Light Olefins

Abstract

In this work, a series of [Zn,Al]ZSM-5 zeolites was synthesized via isomorphous substitution using different Zn precursors, and the as-obtained zeolites were further subjected to Mg–P surface modification for efficient production of p-xylene and light olefins (C2= ≈ C4=) from methanol. The synthesized [Zn,Al]ZSM-5 zeolites are highly active in methanol to aromatics (MTA) reaction. Ascribed to the uniformly dispersed Zn species and greatly enhanced dehydro-cyclization reaction, [ZnS]ZSM-5 synthesized from ZnSO4 exhibited the most efficient MTA performance (∼62 wt % aromatics yield). Through fine modulation of zeolite pore openings and acidic properties, the subsequent Mg–P comodification improved the shape selectivity to p-xylene and also led to abundant coproduction of light olefins. The resultant Mg–P/[ZnS]ZSM-5 catalyst showed an outstanding performance for methanol aromatization in both this work and the open literature, directly yielding ∼23 wt % p-xylene (∼187% para-selectivity) from methanol feedstock.