三油酸甘油酯与甲醇酯交换反应热力学分析

为了揭示酯交换反应的热力学特性,并为动力学研究和生物柴油的工业化生产提供基础数据,采用Benson基团贡献法和其他经验公式计算了三油酸甘油酯与甲醇之间发生的3步连续可逆酯交换反应的焓变、Gibbs自由能变及平衡常数的值,以及在303—338K各值随温度的变化关系。结果表明,在该温度范围内,反应焓接近于0,Gibbs自由能为正值,平衡常数接近于1。说明三油酸甘油酯与甲醇酯交换反应体系的反应热较小,温度对平衡的影响不大。

Thermodynamic analysis for transesterification of triolein with methanol

In order to reveal the thermodynamics characteristics of transesterification and provide basic data for kinetics study and industrial biodiesel production,the thermodynamic calculation of the three consecutive reversible transesterification reactions of triolein with methanol was carried out by Benson group contribution method and empirical formulas. The values of reaction enthalpy,Gibbs free energy change and equilibrium constant were gained,and the relations of them varying with temperature were explored from 303 K to 338 K. The results demonstrate that within such temperature range,the reaction enthalpy is around zero,the standard Gibbs free energy change is positive for each step of the three consecutive reactions,and the equilibrium constant is about 1. It shows that the reaction heat of transesterification reactions is relatively small,and the temperature has little effect on the reaction equilibrium.