环烷酸模型化合物酯化反应体系的热力学分析

Thermodynamics analysis for the esterification of model naphthenic acid compounds

以选取的环烷酸模型化合物为基础,利用热力学方法分析其酯化反应的可能性。由于环烷酸物质结构的特殊性,它们的热力学数据通常无法直接获取,采用了基团贡献法估算酯化反应体系中环烷酸及环烷酸酯在298.15K标准态下的生成焓和标准熵,同时确定了这两种物质等压热容随温度的变化关系,进而得到了不同温度条件下酯化反应的吉布斯自由能变及平衡常数。计算结果表明,酯化反应的平衡常数很大(107),从而确定了该反应体系的可能性。

In this paper,the possibility of the esterification of model naphthenic acid compounds in high acid oil would be verified by thermodynamic analysis method.Due to the particularity of these organic compounds,their thermodynamic date could not be found in literatures.Therefore,the methods of group contribution are applied to estimate the enthalpy and entropy of naphthenic acid,ethylene glycol and naphthenic acid esters under the standard state.Meanwhile,the functional correlations between the heat capacity of these organic compounds and temperature are established.Furthermore,the Gibbs free energy change and equilibrium constant of the esterification reaction are calculated under the different temperature.The result shows that equilibrium constant of the reaction are very large（〉10^7） which prove the esterification reaction of naphthenic acid and ethylene glycol is possible in view of thermodynamics.