One-step bulk fabrication of a CaO/carbon heterogeneous catalyst from calcium citrate for rapid synthesis of dimethyl carbonate (DMC) by transesterification of ethylene carbonate (EC)

Abstract

Dimethyl carbonate (DMC) is well known as an extremely industrially valuable substance. The demand for high-efficiency synthesis of DMC has greatly driven the exploration of novel catalysts and their low-cost preparation methods. Herein, a novel method for the rapid batch preparation of CaO/carbon catalysts using calcium citrate (CaCi) was provided, and these catalysts were used to catalyze the transesterification reaction of methanol and ethylene carbonate (EC) to synthesize DMC and ethylene glycol (EG). Accordingly, the structure and properties of the catalysts were characterized using XRD, FTIR, N₂ adsorption–desorption, TG, TG-IR, CO₂-TPD, XPS, SEM, TEM and ICP-OES techniques. Meanwhile, the effect of various process conditions such as carbonization temperature, reaction temperature, reaction time and catalyst amount has been extensively evaluated. Under the optimal process parameters, the conversion of EC and the selectivity of DMC and EG were 81.2, 99.3 and 99.5%, while the turnover number (TON) and turnover frequency (TOF) were 54.1 and 162 h⁻¹, respectively. Furthermore, kinetic analysis was carried out, and the value of k (reaction rate constant) was ≈0.159 mol L⁻¹ min⁻¹. The reusability was also investigated.