稀土固体超强酸SO_4^(2-)/SnO_2-CeO_2催化合成生物柴油

Synthesis of biodiesel catalyzed by rare earth solid superacid SO_4(2-)/SnO_2-CeO_2

以工业棕榈酸和甲醇为原料,采用溶胶-凝胶法制备稀土固体超强酸催化剂SO42-/SnO2-CeO2,催化合成生物柴油。考察了稀土氧化铈添加量、焙烧温度、焙烧时间、硫酸浓度、醇酸质量比、催化剂用量和反应时间对酯化反应的影响。结果表明,当氧化铈添加量为5%时,在2.0 mol/L硫酸浸渍后,于550℃下焙烧3 h制备的催化剂性能最好。正交试验结果表明,合成生物柴油的优化条件为醇酸质量比为15∶25,催化剂用量为棕榈酸质量的4%,反应时间为4 h,在此条件下,酯化率为95.4%。经GC-MS分析,酯产物主要为直链十六烷酸甲酯和10-十八碳烯酸甲酯。

Biodiesel was synthesized by industrial palmitic acid and methanol,using solid superacid catalyst SO42-/SnO2-CeO2 which was prepared by sol-gel method.Effects of the mole fraction of CeO2 in SnO2-CeO2,the calcination temperature and the time of calcination,the concentration of sulphuric acid,the mass ratio of methanol to industrial palmitic acid,the catalyst dosage and the reaction time on the esterification were investigated.The results showed that SO42-/SnO2-CeO2 exhibited better activity under the conditions of the dosage of CeO2（based on total mole of SnO2-CeO2） of 5%,the calcination temperature of 550 ℃,the calcination time of 3 h,and the concentration of sulfuric acid solution of 2.0 mol/L.The orthogonal test results showed that the optimal reaction conditions of synthesizing biodiesel were as follows： the mass ratio of methanol to palmitic acid was 15∶25,the catalyst quantity was 4.0% of the palmitic acid,the reaction time was 4 h,the esterification rate was 95.4%.Analysis result of GC-MS showed that the ester products were mainly hexadecanoic acid methyl ester and 10-octadecenoic acid methyl ester.