超临界甲醇中制备生物柴油

Production of Biodiesel in Supercritical Methanol

研究了超临界甲醇法制备生物柴油中反应条件对甲酯生成率的影响。结果表明,醇油摩尔比越大,大豆油转化率越高;升温有助于提高反应速率,在临界温度239℃附近,温度的影响尤其明显;当压力高于13.5 MPa时,压力对反应的影响不明显;原料油中,不同脂肪酸酯甲酯化的速率不同,按亚油酸酯、油酸酯、棕榈酸酯、硬脂酸酯的顺序依次降低;大豆油中w(游离油酸)<50%时,不影响反应转化率;原料油中w(H2O)<20%时对反应影响不大。当醇油摩尔比为42∶1,反应温度280℃,反应1 h,油脂转化率可达78%。

Effects of different reaction conditions on the yield of fatty acid methyl esters were investigated. The higher molar ratio of methanol to oil ,the higher yield will be obtained,and the molar ratio of 42：1 is the best one. High temperature enhances the reaction rate, especially near the critical point （239 ℃ ） of methanol. Pressure higher than 13. 5 MPa has less effect on the reaction. In soybean oil ,different acids have various reaction rates. Linoleic acid has the highest reaction rate,followed by oleic acid,palmitic acid and stearic acid. Free oleic acid with a mass concentration less than 50% and water with a mass concentration less than 20% in soybean oil have no obvious effect on the final yield. A yield of 78% has been achieved by reacting methanol and soybean oil in molar ratio 42：1 at 280 ℃ for 1 h.