由二甲醚合成碳酸二甲酯的热力学分析

用Benson基团贡献法计算了碳酸二甲酯(DMC)的标准摩尔生成焓ΔfH0m、标准摩尔生成吉布斯自由能ΔfGθm和压摩尔热容Cp,m。计算了不同温度和压力条件下二甲醚(DME)氧化羰化合成DMC及DME与CO2反应合成DMC的焓ΔrHm、吉布斯自由能变ΔrGm和平衡常数lnKθ。计算结果表明:在300～1000K的温度及0.1～30MPa的压力条件下,DME氧化羰化合成DMC是热力学上可自发进行的反应,而由DME和CO2合成DMC是非自发进行的,需要通过耦合等方来改变反应途径(或重构反应体系),该反应才有可能进行。为由DME合成DMC的反应途径设计和催化剂的探索研究提了热力学依据。

Thermodynamic Analysis for the Synthesis of Dimethyl Carbonate from Dimethyl Ether

The standard enthalpy of formation, free energy and thermal capacity of the synthesis of dimethyl carbonate (DMC) from dimethy ether were calculated using the method of Benson group contributions. The thermodynamic analysis of the synthesis processes was carried out with the emphasis on the calculations of free energy for DMC synthesis from dimethyl ether (DME) with CO and O_2 or DME with CO_2 at different temperature and pressure. Results showed that DMC synthesis by oxidation carbonylation of DME is thermodynamically feasible, but the direct synthesis of DMC from DME and CO_2 is unfeasible. Thus, it is necessary to design other reaction routes for the synthesis of DMC from DME and CO. Optimum reaction conditions for DMC synthesis were investigated, which provides the thermodynamic basis for designing DMC synthesis process and developing catalysts for such process.