Archive | 2021
Modulating Inherent Lewis Acidity at the Intergrowth Interface of Mortise-Tenon Zeolite Catalyst
Abstract
\n The tunability of local structures determines various catalytic performances of zeolite catalysts. The acid sites in zeolite catalysts are important local structures to control the products in methanol conversion. However, it remained still a great challenge to precisely design the acid sites, since there is a lack of controllable methods to generate and identify the acid sites with a high resolution. Here, we use the lattice mismatch of zeolite intergrowth to enrich the inherent Lewis acid sites (LASs) at the interface of a mortise-tenon ZSM-5 catalyst (ZSM-5-MT) showing a 90° intergrowth structure. ZSM-5-MT is formed by two perpendicular blocks that can be atomically resolved by the integrated differential phase contrast scanning transmission electron microscope (iDPC-STEM). It can be revealed by various methods that more framework-associated Al (AlFR) LASs are generated in ZSM-5-MT than single-crystal ZSM-5 catalyst. Combining with the iDPC-STEM results, we demonstrate that the partial missing of O atoms at interfaces results in the formation of inherent LASs in ZSM-5-MT. According to the catalytic performances, LAS-enriched ZSM-5-MT shows a higher selectivity of light olefins than the single-crystal ZSM-5 catalyst in methanol conversion. These results provide an efficient strategy to design the Lewis acidity in zeolites for tailored catalytic functions via interface engineering.