Construction of Mesopores and Skeleton Si–Al Rearrangement to Design Pd-Based Catalysts for Dimethyl Carbonate Synthesis

Abstract

Dimethyl carbonate (DMC), a widely used green chemical, has garnered significant attention. Chlorine-free catalytic technology for the carbonylation of methyl nitrite (MN) to DMC has considerable potential for various applications. Currently, research efforts are concentrated on improving the performance of Pd–NaY catalysts. The Lewis acidity and pore structure of the molecular sieve determine the distribution of the Pd species and their electronic structure. In this paper, a strategy of continuous acid–base treatment was employed to design a novel catalyst. It was found that the rearrangement of skeleton Si and Al occurred after the acid–base treatment, which regulated the acidity of the NaY molecular sieve. Additionally, a new mesoporous structure appeared that facilitated the transport of reactants and products. The regulation of NaY molecular sieve acidity enabled more efficient utilization of the active Pd species, helped maintain the Pd species in their oxidation state, and promoted the formation of the active intermediate species *COOCH₃, thereby improving the catalytic performance. The DMC yield of the PdCu/Y-CAT catalyst reached 1591 g·kg_cat^–1·h^–1. Acid–base treatment is an efficient method to design metal-zeolite catalysts, which facilitates the industrial application of chloride-free catalysts in the MN carbonation of the DMC route.