L-乳酸熔融缩聚变容反应动力学

Variable Volume Reaction Kinetics of L-Lactic Acid Melt Polycondensation

以对甲苯磺酸为催化剂，在150～180℃、绝对压力小于100Pa的条件下，进行L-乳酸熔融缩聚反应动力学实验。由反应机理建立了L-乳酸熔融缩聚变容反应动力学模型。采用微分法对实验数据进行处理，采用积分法对变容反应动力学模型进行辨识和检验，确定L-乳酸熔融缩聚反应属二级反应，活化能为35．17kJ／mol，指数前因子为3．865×10^3L／（mol·h）。用MathCAD软件对不同温度控制条件下L-乳酸熔融缩聚反应的过程进行了模拟计算，提出适宜采用程序升温的控制方案。

Reaction kinetics of L - lactic acid melt polycondensation was studied in the temperature range of 150 - 180 ℃ under lower than 100 Pa absolute pressure with toluene -p - sulfonic acid as catalyst. Water as byproduct formed in the polycondensation and was continuously removed from the reaction system. So the system is considered as a variable volume system. Variable volume reaction kinetic models of L - lactic acid melt polycondensation were established according to reaction mechanism. The reaction kinetic parameters were determined by differential method. The reaction kinetic models were tested by integral method. L - lactic acid melt polycondensation kinetics coincides with second order variable volume reaction. Apparent active energy and preexponential factor of the model are 35.17 kJ/mol and 3. 865 × 10^3 L/（ mol·h）, respectively. Both constant temperature and temperature programmed reaction processes were simulated with MathCAD software. Advice of adopting temperature programming in the polycondensation was stated.