Effect of Gel Alkalinity on the Catalytic Properties of PdCu/NaY Zeolites for Methyl Nitrite Carbonylation to Dimethyl Carbonate

Abstract

The carbonylation of methyl nitrite (MN) to synthesize dimethyl carbonate (DMC) is a promising route, but the lack of efficient and stable catalysts remains a major challenge for large-scale applications. In this study, by adjusting the alkalinity of the initial gel, NaY zeolites with tunable acidity were synthesized, and the amount of Lewis acid sites was optimized. Appropriate amounts of Lewis acid sites facilitated the interaction between NaY zeolites and Pd species, which was beneficial for stabilizing the oxidation state of Pd and promoting CO adsorption and activation, thereby contributing to the formation of the key intermediate *COOCH₃. The catalyst PdCu/NaY-1 (alkalinity in the initial gel Na₂O=9) exhibited significant improvement in catalytic performance for the synthesis of DMC, with the WTY_DMC of 1604 g kg_cat⁻¹⋅h⁻¹, the conversion of CO to DMC (C_CO) of 88.7 %, and the DMC selectivity based on CO (S_DMC/CO) up to 100 %.