响应面法优化L-谷氨酸离子液体催化制备油酸甲酯Optimization of L-glutamic acid ionic liquid catalyzed preparation of methyl oleate by response surface methodology

Abstract

为了开发环境友好型高效催化剂催化油酸酯化制备生物柴油，以L-谷氨酸与不同无机酸（硫酸、硝酸和磷酸）为原料合成了3种离子液体，对这3种离子液体催化油酸酯化反应制备油酸甲酯的酯化率进行了考察，筛选出催化效率较优的一种离子液体，对其进行傅里叶红外光谱表征，并进一步采用响应面法对其催化油酸酯化反应的工艺参数进行优化。结果表明：在3种离子液体中\[L-Glu\]HSO4的催化效率最高；\[L-Glu\]HSO4催化油酸酯化的最佳反应条件为离子液体用量15%、醇酸摩尔比11∶ 1、反应温度70 ℃、反应时间12 h，在此条件下酯化率为97.02%。因此，所合成的\[L-Glu\]HSO4可以高效催化油酸酯化制备生物柴油。 In order to develop environmentally friendly and efficient catalysts to catalyze the esterification of oleic acid for the preparation of biodiesel, three ionic liquids were synthesized from L-glutamic acid and different inorganic acids (sulfuric acid, nitric acid and phosphoric acid), and the esterification rates of these three ionic liquids for the catalytic esterification reaction of oleic acid to prepare methyl oleate were investigated, and one ionic liquid with better catalytic efficiency was selected and characterized by Fourier infrared spectroscopy, and the process parameters of the catalytic oleic acid esterification reaction were further optimized by response surface methodology. The results showed that the catalytic efficiency of \[L-Glu\]HSO4 was the highest among the three ionic liquids, and the best reaction conditions for the catalytic esterification of oleic acid by \[L-Glu\]HSO4 were as follows: ionic liquid dosage 15%, molar ratio of alcohol to acid 11∶ 1, reaction temperature 70 ℃, and reaction time 12 h. The esterification rate was 97.02% under the best conditions. Therefore, the synthesized \[L-Glu\]HSO4 can efficiently catalyze the esterification of oleic acid to prepare biodiesel.

Keywords

• l-谷氨酸离子液体；油酸甲酯；酯化反应；生物柴油；响应面法
• l-glutamate ionic liquid; methyl oleate; esterification reaction; biodiesel; response surface methodology