醋酸甲酯加氢反应的热力学计算与分析

Thermodynamic Analysis for Hydrogenation of Methyl Acetate

对醋酸甲酯加氢制乙醇反应体系进行了热力学分析.计算了各独立反应的标准摩尔反应吉布斯自由能,分析了温度、压力、氢气与醋酸甲酯的摩尔比（氢酯比）对反应体系平衡组成的影响以及对醋酸甲酯转化率和乙醇选择性的影响.计算和分析结果表明,各独立反应在423 ～723 K内的标准摩尔吉布斯自由能均大于0,没有适宜的压力和氢酯比反应将很难进行;较低的温度有利于乙醇的生成和抑制副产物的产生,适宜的温度为423 ～550 K;在压力低于2.0MPa时,醋酸甲酯转化率和乙醇选择性均随压力的升高而快速增加,适宜的压力为2.0～3.0 MPa;在氢酯比低于10时,醋酸甲酯转化率和乙醇选择性均随氢酯比的增大而快速增加,适宜的氢酯比为10～ 20.

The thermodynamics of methyl acetate hydrogenation system was studied and the Gibbs free energies of the reactions in the system were calculated. The effects of temperature, pressure and the molar ratio of hydrogen to methyl acetate on the equilibrium composition, methyl acetate conversion and ethanol selectivity were investigated. The results showed that the standard Gibbs free energies of all the reactions were more than 0 when the reaction temperature was in the range of 423 - 723 K, so the reactions should be carried out under suitable pressure and the appropriate molar ratio. Low temperature is beneficial to the production of ethanol and can inhibit the generation of by-products, and the suitable reaction temperature is in the range of 423 - 550 K. The conversion of methyl acetate and the selectivity to ethanol quickly increased with the pressure rise while the pressure is less than 2.0 MPa, so the suitable reaction pressure is in the range of 2.0 - 3.0 MPa. The conversion of methyl acetate and the selectivity to ethanol are very sensitive to the molar ratio of hydrogen to methyl acetate at the ratio less than 10, so the suitable molar ratio is in the range of 10 -20.