金属氧化物催化棕榈酸制备生物柴油工艺及其动力学研究

Process and Its Kinetics Study on Catalytic Synthesis of Biodiesel from Palmitic Acid Using Metal Oxide as Catalysts

采用溶胶-凝胶法制备系列大表面金属氧化物,并以其为催化剂催化棕榈酸与甲醇反应制备生物柴油棕榈酸甲酯,同时考察了催化剂种类、醇酸摩尔比、催化剂用量、反应时间及反应温度等因素对酯化反应的影响。研究结果表明,金属氧化物CeFeTiO催化剂表现出最好的催化酯化活性,强酸性及大的比表面积是其具有高活性的原因;以CeFeTiO为催化剂,利用响应面分析法优化所得棕榈酸甲酯的产率为93.2%,结果与模型预测值基本相符。优化条件下,合成棕榈酸甲酯反应的活化能为22.18 kJ/mol,反应级数为1.54,动力学方程为:r=-d C_(A)/d_(t)=12.25 exp(22.18/RT)C_(A)^(1.54)。

Methylpalmitate was synthesized by the esterification of palmitic acid and methanol with metal oxide prepared by sol-gel as catalyst.The effects of different catalyst,alcohol/acid molar ratio,catalyst amount,reaction time and reaction temperature were also investigated.The results showed that CeFeTiO catalyst exhibited superior performance during synthetic process.The strong acidity and high surface area account for the the high activity of the catalyst.Using CeFeTiO as catalyst,the optimized yield of methyl palmitate obtained by response surface methodology(RSM)is 93.2%,which is basically consistent with the experimental results.Moreover,under optimal reaction conditions,the active energy of methyl palmitate synthesis reaction was 22.18 kJ/mol,the reaction order was 1.54,and the kinetic equation can be expressed as:r=-d C_(A)/d_(t)=12.25 exp(22.18/RT)C_(A)^(1.54).