Selective preparation and reaction kinetics of dimethyl carbonate from alcoholysis of methyl carbamate with methanol over ZnAl-LDO

Abstract

In this paper, an optimal composite metal oxide ZnAl-LDO catalyst, which was prepared from Zn/Al layered double hydroxides (ZnAl-LDHs) as the precursor, has been evaluated for the synthesis of dimethyl carbonate (DMC) by methyl carbamate (MC) alcoholysis. The composite metal oxide achieved a selectivity of 58.26% for DMC production under optimal reaction conditions (the catalyst calcination temperature is 873 K, the molar ratio of methanol to MC is 15, the catalyst weight percentage is 1 wt%, and the reaction temperature and reaction time are 453 K and 10 h). The influence of the structural characteristics of the catalyst on its catalytic performance was investigated by characterizing the catalyst. The kinetic model of the catalytic reaction was established and modified. According to the fitting results, it can be concluded that the reaction process conforms to the Langmuir–Hinshelwood kinetic model, and the kinetic parameters were obtained by the Arrhenius formula (the pre-exponential factor was 1.21 × 10⁶ and the activation energy was 56.34 kJ mol⁻¹). At the same time, the reaction enthalpy (Δ_rH⁰_m = 106.203 kJ mol⁻¹) and Gibbs free energy (Δ_rG⁰_m = 59.389 kJ mol⁻¹) were determined by thermodynamic calculation of the reaction equation.