碳酸亚乙烯酯合成体系的热力学计算与分析

Thermodynamic calculation and analysis of vinylene carbonate synthesis system

采用Joback基团贡献法估算碳酸乙烯酯(EC)、氯代碳酸乙烯酯(CEC)和碳酸亚乙烯酯(VC)的热力学数据,并分析了氯代合成法和直接脱氢法合成VC的热力学特性。计算结果表明,在氯代合成法中,EC与Cl_(2)生成CEC的氯代反应步骤在313~433 K是放热且自发的,但随着温度升高,反应的自发性降低,标准平衡常数(K^(Θ))减小;氯代合成法中CEC脱氯生成VC的反应步骤在313~433 K是吸热且自发的,随着温度的升高,反应的吸热程度增加,但反应的自发性降低,K^(Θ)减小;直接脱氢法中EC直接脱氢生成VC的反应在373~873 K是吸热的,在373~673 K是非自发的,但在温度高于673 K时,反应则转变为自发的,且随着温度的进一步升高,反应的自发性增强,K^(Θ)随温度升高而增大。

The thermodynamic data on ethylene carbonate(EC),chlorinated ethylene carbonate(CEC),and vinylene carbonate(VC)were estimated using the Joback group contribution method,and the thermodynamic properties of VC synthesized via chlorination and direct dehydrogenation were analyzed.Calculations result show that in the chlorination method,the reaction step of EC with Cl_(2) to form CEC is exothermic and spontaneous at temperatures between 313 K and 433 K.However,as the temperature increases,the spontaneity of the reaction decreases,and the standard equilibrium constant(K^(Θ))also decreases.In the chlorination method,the dechlorination of CEC to produce VC is endothermic and spontaneous in the same temperature range(313-433 K).As the temperature rises,the degree of heat absorption of the reaction increases,but the spontaneity of the reaction decreases and KΘdecreases.In the direct dehydrogenation method,the reaction of direct dehydrogenation of EC to produce VC is endothermic over the temperature range of 373-873 K and is non-spontaneous at 373-673 K.However,the reaction becomes spontaneous at temperatures higher than 673 K,with spontaneity enhancing as the temperature increases,accompanied by a rise in K^(Θ).