乳酸甲醇酯化床催化研究

为研究乳酸甲醇酯化反应过程，采用强酸性阳离子交换树脂床催化乳酸甲醇酯化反应，研究反应物进料流速、反应温度、醇酸物质的量比对酯化率的影响。结果表明：随进料速度的降低，酯化率先上升后趋于稳定；随反应温度升高，反应速率变大，平衡酯化率基本不变；随醇酸比增加，平衡转化率升高，但增加幅度变小。建立乳酸甲醇床催化拟均相模型，反应活化能为33805.56J/mol，指前因子为4856.63mol-1·L·min-1。实验测得平衡常数为1.1151，且在所考察的温度范围内基本不变。实验值与模型估计值平均相对偏差为2.74%。

Fixed Bed Esterificaiton of Lactic Acid with Methanol

The esterification-hydrolysis method has been reported to be an effective technique for the refining of crude lactic acid product, which based on the principle that lactic acid is easy to react with lower alcohols to form volatile esters, which donate high-purity lactic acid after being hydrolyzed. Under the catalysis of strong acid cation exchange resin bed, the esterification between lactic acid and methanol was performed in the present study. The effects of feed flow rate, reaction temperature and acid/alcohol molar ratio on esterification rate were examined. As the feed flow rate descended, the esterification rate showed a change trend to initially ascend and then keep stable. Increasing reaction temperature led to a higher reaction rate, but the equilibrium esterification rate was kept basically unchanged. With increasing acid/alcohol molar ratio, the equilibrium esterification rate revealed a smaller incremental increase. The reaction rate data were correlated with a kinetic model based on the pseudohomogeneous catalysis. The activation energy, pre-exponential constant and equilibrium constant of the reaction were found to be 33805.56 J/mol, 4856.63 mol-1·L·min-1, and 1.1151, respectively. The mean relative deviation between the experimental and predicted values was 2.74%.