Tuning the Spatial\nDistribution and Chemical Nature\nof Acid Sites in MCM-22 Zeolite by Atomically Dispersed Lanthanum\nSpecies for Alkylation of 2‑Methylnaphthalene

Rare-earth-promoted\nzeolites have broad applications\nin the petrochemical\nindustry because modifying zeolites with rare-earth elements can remarkably\nimprove hydrothermal stability and tune the physicochemical properties\nof the acid sites, resulting in substantial promotion in catalytic\nselectivity and long-term stability. However, for a specific reaction,\nit remains a challenge to elaborate the coordination environment of\nrare-earth elements within the zeolite structure and establish the\nstructure–reactivity of rare-earth-promoted zeolite catalysts.\nIn this work, we have employed multiple spectroscopy and electron\nmicroscopy techniques to elucidate the spatial location and coordination\nenvironment of atomically dispersed La species in MCM-22 concertedly.\nIn particular, we have attempted to clarify the variation of the chemical\nnature of the acid sites in MCM-22 zeolite in response to the introduction\nof La promotor. By appropriately controlling the spatial distribution\nand chemical nature of the acid sites, we have obtained a La-modified\nMCM-22 catalyst with high activity, selectivity, and long-term stability\n(>800 h) for alkylation of 2-methylnaphthalene with methanol for\nthe\nproduction of 2,6-dimethyl-naphthalene under industrially relevant\nconditions.