Study On Preparation Of Fatty Acid Methyl Ester By External Circulation Reactive Distillation

The production status and reaearch development of the fatty acid methyl esters at home and abroad were reviewed in this paper. On the basis of the domestic and foreign literatures, the methods of synthesizing fatty acid methyl esters were analyzed. Meanwhile, the method of external-cycling reactive distillation by using solid acid Zr(SO4)2/TiO2as the catalyst to produce fatty acid methyl esters was put forward.The solid acid catalyst Zr(SO4)2/TiO2has the advantages of high catalytic activity, simple separation, no corrosiveness for apparatus, no acidic by-products, and easy reuse. In this paper, effects of the mass fraction of Zr(SO4)2in the catalyst, calcination temperature and time of the catalyst on the esterification rate while preparing solid acid catalyst Zr(SO4)2/TiO2were investigated, and the solid acid Zr(SO4)2/TiO2catalyst was characterized. The results showed that the mass fraction of Zr(SO4)2in the catalyst about65%, calcination temperature about430℃and calcination time of the catalyst about2.5h were the optimum preparing conditions.The orthogonal tests were come by, which provided an effective basis for further enlarged experiments research of the solid acid catalyst Zr(SO4)2/TiO2.By using solid acid Zr(SO4)2/TiO2as the catalyst, and the industrial palmitic acid and methanol as the raw materials,the method of external-cycling reactive distillation was put forward to produce the fatty acid methyl esters in order to investigate the effects of reaction time, catalyst dosage and the mass fraction of the volume to mass ratio of methanol to industrial palmitic acid on the conversion of the esterification reaction. The results showed that the conversion can reach91.97%under the conditions of the mass fraction of the volume to mass ratio of methanol to industrial palmitic acid about2.5mL/g, catalyst dosage about8%(to the mass of palmitic acid) and reaction time about4h.The reaction kinetics equation of the esterification reaction by using solid acid Zr(SO4)2/TiO2as the catalyst, industrial palmitic acid and methanol as the raw materials was also studied. The kinetics calculation of esterification reaction at different temperatures indicated that the reaction order and activation energy of the esterification reaction was1.2and7726.83J/mol, and the reaction kinetics model was-dcA/dt=13.42e-7726-83/RTCA1.2。Synthesing fatty acid methyl esters by reactive distillation was simulated by Aspen Plus. The results showed that the reflux ratio was1.5; the rectifying section, reaction section and stripping section stage number were respectively11,9,9; the palmic acid feed from11th stage,while the methol20th were the optimum process conditions.