Stabilization of Pd Active Sites by Defective NaY Zeolite Framework for Enhanced Stability in Dimethyl Carbonate Synthesis

ABSTRACT Stabilizing palladium in its oxidized state under reducing reaction atmospheres remains a significant challenge. To address this, we developed a tailored‐defect strategy using sequential high‐temperature calcination and acetylacetone treatment. This approach introduces framework defects into the NaY zeolite while simultaneously suppressing the formation of strong acid sites, thereby avoiding the associated decrease in product selectivity. The modified Pd/NaY catalyst featuring an optimal defect density exhibits significantly improved stability compared to a reference Pd/NaY, maintaining 97.3% ± 0.9% CO conversion and 76% ± 3.4% selectivity for over 150 h in the indirect oxidative carbonylation of methanol to dimethyl carbonate. This stable catalyst, characterized by a turnover frequency (TOF) of 0.11 s −1 and an average Pd cluster size of 1.6 nm, derives its durability from the framework defects. Nuclear magnetic resonance (NMR) and in situ infrared (IR) spectroscopy reveal that defects, manifesting as Si–OH and Al–OH groups, act as effective anchoring sites that inhibit Pd sintering. Furthermore, X‐ray absorption near‐edge structure (XANES) and X‐ray photoelectron spectroscopy (XPS) demonstrate that these sites facilitate electron transfer from Pd to the zeolite framework, generating electron‐deficient Pd species. It is these defect‐stabilized Pd 2+ active sites that are ultimately responsible for the exceptionally enhanced catalytic stability observed for dimethyl carbonate synthesis.