HFC-245fa催化裂解合成HFO-1234ze和HFO-1234yf的热力学研究

Thermodynamic Study on the Synthesis of HFO-1234ze and HFO-1234yf via Gas-Phase Dehydrofluorination of HFC-245fa

采用密度泛函理论(DFT)方法,使用Materials Studio的DMol 3模块,计算了1,1,1,3,3-五氟丙烷(HFC-245fa)气相裂解脱氟化氢生成1,3,3,3-四氟丙烯(HFO-1234ze)和2,3,3,3-四氟丙烯(HFO-1234yf)反应及其副反应体系中各物质的标准摩尔焓和标准摩尔吉布斯自由能。通过比较不同温度下各反应的标准摩尔焓变和标准摩尔吉布斯自由能变,对反应过程进行了热力学分析。结果表明:HFC-245fa脱HF生成HFO-1234ze的反应为吸热反应,标准摩尔吉布斯自由能变随着温度的升高而减小;当反应温度更高时,E构型的HFO-1234ze能异构化反应合成HFO-1234yf;高温有利于HFO-1234yf的生成。

The standard enthalpy and Gibbs free energy during the synthesis of 1,3,3,3-tetrafluoropropene（ HFO-1234ze） and 2,3,3,3-tetrafluoropropene（ HFO-1234yf） via gas-phase catalytic dehydrofluorination of 1,1,1,3,3-pentafluoropropane（ HFC-245fa） was estimated based on density functional theory（ DFT） using Materials Studio DMol 3 calculations. By comparing the changes of standard enthalpy and Gibbs free energy as a function of reaction temperature for each independent reaction, thermodynamics of the reaction process was analyzed. The results showed that the synthesis of HFO-1234 ze by dehydrofluorination of HFC-245 fa was an endothermic reaction, and the change of standard Gibbs free energy declined with the increasing reaction temperature. The isomerization of HFO-1234ze（ E） to HFO-1234 yf can occur at higher reaction temperature,while high temperature was favorable for the formation of HFO-1234 yf.