Structured Pd–Cu/NaY Catalyst for Industrial Syngas to DMC: Enhanced Stability and Mechanism

A structured, chloride-free Pd–Cu/NaY catalyst was developed for the direct synthesis of dimethyl carbonate (DMC) from syngas-derived methyl nitrite and CO. The NaY zeolite support stabilizes Pd(II) species via strong electrostatic interactions, while Cu addition enhances durability by suppressing Pd reduction and aggregation, as confirmed by H 2 -TPR and TEM. Using shaped spherical supports improves DMC selectivity by limiting methyl nitrite decomposition side reactions through diffusion constraints. Under optimized conditions (CO/MN = 1/6, 120°C), the catalyst achieves a DMC space-time yield of 669 g·kg −1 ·h −1 with high selectivity. A 1000 h stability test shows sustained activity above 550 g·kg −1 ·h −1 after an initial run-in period. In situ DRIFTS studies identify the ligand exchange step as rate-determining and elucidate the full reaction pathway. This robust catalytic system demonstrates strong potential for pilot-scale and industrial syngas-to-DMC processes.