标准态下碳酸二甲酯合成体系热力学分析

 用Benson基团贡献法计算了碳酸二甲酯(DMC)的热力学数据标准摩尔生成焓Δ_fH_m^θ、标准摩尔生成吉布斯自由能Δ_fH_m^θ和等压摩尔热容C_p,m;在标准态下,300~1 000 K温度范围内对比了甲醇或二甲醚(DME)氧化羰化合成DMC,甲醇或DME与CO₂直接合成DMC,由合成气合成DMC,DME,甲醛或甲醇这些反应的焓变Δ_fH_m^θ、吉布斯自由能变Δ_fH_m^θ和平衡常数lnK^θ.计算结果表明:在讨论的条件范围内,由DME氧化羰化合成DMC是热力学上可自发进行的反应,但DME和CO₂反应合成DMC与甲醇和CO₂反应合成DMC,均不能自发进行(需要通过耦合等方式来改变反应途径或重构反应体系,该反应才有可能进行).此计算将为合成DMC的反应路线设计以及新催化剂体系的探索提供热力学依据.

Studies on thermodynamic analysis for synthesis of dimethyl carbonate

The standard enthalpy of formation,free energy and thermal capacity of dimethyl carbonate(DMC) were calculated by using the method of Benson group contributions.The thermodynamic data of various syntheses of DMC were compared at different temperatures.The syntheses induded oxidation of methanol or dimethyl ether,reaction of methanol or dimethyl ether with CO_2,and preparations of DMC,DME,formaldehyde and methanol from H_2 and CO.The results showed that the synthesis of DMC by oxidation carbonylation of DME is thermodynamically feasible,but the syntheses of DMC from DME and CO_2 and from methanol and CO_2 and are all thermodynamically unfeasible.These results provided the thermodynamic basis to design the synthesis process and catalyst for DMC.