硅胶固载磺酸功能化离子液体催化棕榈酸制备生物柴油的工艺研究

Catalytic Synthesis of Biodiesel from Palmitic Acid with Silica Gel-Based Sulfonic Acid Functionalized Ionic Liquid as Catalysts

以硅胶固载N,N-二甲基苄胺丙基磺酸基硫酸氢盐离子液体([DMBPSH]HSO4/SG)为催化剂,进行棕榈酸与甲醇酯化制备生物柴油工艺研究,考察了醇酸摩尔比、催化剂用量、反应时间及反应温度等因素对棕榈酸甲酯收率的影响。研究表明,10%[DMBPSH]HSO4/SG催化剂具有最好的催化酯化活性;以10%[DMBPSH]HSO4/SG为催化剂,利用响应面分析法优化生物柴油的最佳制备工艺条件为:醇酸摩尔比12.6∶1,催化剂用量为棕榈酸质量的5.3%,反应时间2.3h,温度368K,此条件下,棕榈酸甲酯的收率为97.2%,该结果与模型预测值基本相符。最佳条件下,棕榈酸甲酯合成反应的活化能为15.89kJ/mol,动力学方程为:r=-dCA/dt=8.23exp(15.89/T)CA^1.48。

The preparation of biodiesel by esterification of methyl palmitate acid with methanol was studied with N,N - dimethyl ( benzyl) ammonium propyl sulfobetaine hydrosulfate embedded silica gel ([DMBPSH]HSO4 /SG) as catalyst.The effects of alcohol /acid molar ratio,catalyst dosage,and the effects of reaction time and temperature on the yield of methyl palmitate were also investigated.Study showed that the 10%[DMBPSH]HSO4 /SG catalyst was found to exhibit superior performance during synthetic process.Moreover,an experimental design was exploited through response surface methodology ( RSM) for the optimization of process variables.Accordingly,the reaction conditions were optimized as follows:methanol /palmitic acid molar ratio of 12.6:1,catalyst amount of 5.3 wt% and reaction time of 2.3 h at a temperature of 368 K,which contributed to a maximum methyl palmitate yield of 97.2%. These values were in close agreement with the mathematical model.Under optimized conditions,the activation energy of methyl palmitate synthesis reaction was 15.89 kJ /mol,and the kinetic equation is expressed as r=-dCA/dt=8.23exp(15.89/T)CA^1.48.