关键词: 基团贡献法, 生物柴油, 酯交换反应, 热力学, Gibbs函数

Abstract: Biodiesel (FAME) is a biodegradable clean energetic resource comprised by a mixture of monoalkyl esters of long chain fatty acids that can be obtained from a wide variety of raw materials. The thermodynamics of transesterification reaction of triglyceride for production of biodiesel is simulated and evaluated using Gibbs energies method. The results obtained can be used to reacting systems to produce biodiesel, based on the transesterification. The thermodynamic calculation of the three consecutive reversible transesterification reactions of triolein with methanol was carried out by means of group-contribution methods and Zhao’s empirical formulas，ΔS? v = A s lgT b + B s . Factors affecting the conversion rate are studied in transesterification of triolein and methanol. From this analysis, it is concluded that the reaction enthalpy is -10.742 kJ?mol-1 at 298 K, showing a slightly exothermic reaction. The reactions are performed easily at lower temperature and higher pressure. The conversion rate of triolein in liquid methanol is smaller change at condition of temperature and pressure. Increase in molar ratios of methanol to triolein, results in increase in conversion of triolein. The equilibrium conversion of triolein reaches 98.8% at molar ratios of 20:1, methanol to triolein. Increase in pressure of methanol vapor, results in increase in triolein conversion, while an increase in temperature of methanol vapor results in a decrease in triolein conversion. Compare with results of experimental data from references, the group-contribution analysis method is feasible.