草酸二甲酯催化加氢合成乙二醇过程的热力学计算与分析

Thermodynamics of Ethylene Glycol Synthesis via Hydrogenation of Dimethyl Oxalate

采用Benson基团贡献法估算得到草酸二甲酯(DMO)和乙醇酸甲酯的标准生成焓和标准生成吉布斯自由能,结合其他已知的热力学数据计算了DMO催化加氢合成乙二醇(EG)反应中所涉及的反应焓变、反应熵变、反应吉布斯自由能变和反应的化学平衡常数。在此基础上,分析了反应温度、反应压力、n(H_2):n(DMO)和DMO含量对DMO转化率和EG选择性的影响。分析结果表明,当反应温度473K、反应压力2.5 MPa、n(H_2):n(DMO)=40、DMO质量分数不小于15%时,DMO转化率和EG选择性均大于99%;继续增大反应压力、n(H_2):n(DMO)及DMO含量对DMO转化率和EG选择性的影响不明显。

Both standard enthalpy of formation and standard Gibbs free energy of formation of both dimethyl oxalate （DMO） and methyl glycollate was estimated by Benson group contribution method. Together with basic chemical thermodynamic data obtained from chemistry and engineer handbooks, reaction enthalpy change, reaction entropy change, reaction Gibbs free energy change and equilibrium constant of relevant reactions occurred in reaction system were calculated and analyzed. Effects of reaction temperature, reaction pressure, n （ H2 ） ： n （ DMO ）, mass fraction of DMO in methanol （WDMO） on conversion of DMO and selectivity to ethylene glycol （EG） were investigated. Under the conditions of reaction temperature 473 K, reaction pressure 2.5 MPa, n（H2 ）： n（DMO） 40 and WDMO ≥ 15%, both conversion of DMO and selectivity to EG exceed 99%. With further increasing of pressure, n （ H2 ）： n （DMO） and w both conversion of DMO and selectivity to EG keep steady.