Acid site engineering of HSUZ-4 zeolite via zirconium nitrate treatment for efficient dimethyl ether carbonylation

Zeolite-catalyzed carbonylation of dimethyl ether(DME) to methyl acetate(MA) is a pivotal step in the syngas-to-ethanol process, yet designing zeolites with both high activity and long-term stability remains a central challenge. Herein, a mild post-synthetic treatment using Zr(NO 3 ) 4 solutions of varying concentrations was applied to HSUZ-4 zeolite to tailor its acid sites. The optimized catalyst, Zr-HSUZ-4(0.01), achieved a DME conversion of 30.0% and a MA selectivity of 95.1%, nearly doubling the activity of the parent zeolite under identical reaction conditions. Combined characterization and DFT analyses reveal that Zr(NO 3 ) 4 solution treatment induces selective changes in framework Al sites and leads to the formation of Zr-related Lewis acid sites (LAS), primarily associated with the 10-membered ring channels. These LAS facilitate CO adsorption and polarization, while the adjacent Brønsted acid sites (BAS) in the 8-membered ring channels promote DME activation and methoxy formation. Electronic interactions between the two types of acid sites enhance BAS strength and create a cooperative Brönsted-Lewis acid ensemble that lowers the energy barrier for acetyl formation, the rate-determining step in carbonylation. This work demonstrates a rational strategy for tailoring zeolite acidity and provides molecular-level insights into the synergistic role of BAS and LAS in DME carbonylation catalysis. Zr(NO 3 ) 4 post-treatment reconstructs the acidity of HSUZ-4 via framework dealumination and Zr incorporation, leading to Brönsted-Lewis acid synergy and enhanced DME carbonylation performance. • 1.Zr(NO 3 ) 4 post-treatment creates a Zr-modified HSUZ-4 catalyst with enhanced DME carbonylation activity. • 2.Controlled dealumination anchors Zr species as LAS in 10-MR channels and increases BAS density in 8-MR channels. • 3.Neighboring Zr-LAS and BAS cooperatively activate CO and methoxy, lowering the acetyl barrier.