Functionalized UiO‐66 as Catalyst for Direct Synthesis of Dimethyl Carbonate from CO ₂ and Methanol

Abstract

Abstract To precisely regulate the distribution of acid–base active sites on the catalyst surface, five types of functionalized UiO‐66‐X catalysts were prepared. The results of the catalyst characterization and activity evaluation showed that the electron‐withdrawing ability of ─F, ─Cl, and ─Br decreased, which led to the gradual increase of weakly acidic sites on the catalyst surface, thus, the catalytic activity increased in turn. In particular, the UiO‐66─Br catalyst with the largest weak acid sites exhibited the best catalytic performance with a high DMC formation rate. Moreover, UiO‐66─NH 2 and UiO‐66─OH had more weak acid sites than UiO‐66, but fewer total acid–base active sites and showed lower catalytic activity. Therefore, it can be concluded that appropriate acid–base type and ratio were also crucial for the design of the catalyst in the synergistic activation of CO 2 and methanol. Furthermore, the reaction kinetics of the UiO‐66─Br catalyst were investigated.