Acid–base bifunctional ZnNbCl/eg-C3N4 materials towards catalytic synthesis of dimethyl carbonate via transesterification of ethylene carbonate

Abstract

The catalytic transesterification reaction between ethylene carbonate (EC) with methanol is a sustainable approach for the production of dimethyl carbonate (DMC). In this work, exfoliated carbon nitride (eg-C3N4) was supported with ZnCl2 and NbCl5. The synthesized materials (ZnNbCl/eg-C3N4) were analyzed by XRD, N2 adsorption–desorption, FT-IR, XPS, SEM, TG, CO2-TPD, and NH3-TPD. The eg-C3N4 could disperse well Zn2+ and Nb5+ species via nitrogen-containing groups. The combined Zn2+ and Nb5+ components enhanced the alkaline strength of eg-C3N4 and introduced acidic sites, enabling ZnNbCl/eg-C3N4 as solid-base bifunctional catalysts. As heterogeneous catalysts, ZnNbCl/eg-C3N4 exhibited superior activity to ZnCl2/eg-C3N4 or NbCl5/eg-C3N4 in the transesterification of EC. At 140 °C of reaction temperature, EC conversion and DMC selectivity reached 80.1% and 100%, respectively. The catalysts showed good recycling performance and were also compared with other recently reported heterogeneous catalysts.