Production Of Biodiesel From Jatropha Oil With High-Acid Value By Pre-Esterification And Transesterification

As the non-renewable resource petroleum is going depleted and the ecological environment is deteriorating, searching for renewable and clean type of alternative energy becomes effective measures to solve the energy crisis and environment issues. As a renewable and environment-friendly green fuel, biodiesel can be an alternative to conventional diesel fuel for its performance similar to conventional diesel fuel. Jatropha curcas has many advantages, such as high oil content, and high economic value. Jatropha biodiesel has good compatibility with petroleum diesel. Replacing by soybean oil and rapeseed oil, Jatropha oil is becoming an acclaimed raw material for biodiesel.Saponification will occur when high acid value Jatropha oil is esterified. In this paper, H3PW12O40as a catalyst catalyzed esterification of high acid value Jatropha oil, meeting the subsequent base-catalyzed transesterification reaction requirement that the acid value of less than1.0mg KOH·g-1. The effect of esterification process conditions on the acid-lowering effect was studied; the optimum esterification condition was reaction temperature65℃, reaction time3h, molar ratio of methanol to oil9:1, and catalyst amount1%wt. Under the optimum esterification condition, the highest esterification rate was96.1%, and the acid value was reduced from15.74to0.61mg KOH·g-1. KOH/Al-pillared bentonite as a solid base catalyst catalyzed the transesterification of Jatropha oil that had been esterified. The influence of KOH load and transesterification reaction condition on the conversion rate of biodiesel was studied. It was found that KOH/Al-pillared bentonite catalyst with15%KOH load showed the optimum condition. When the transesterification was carried out under the optimum condition with catalyst amount7%, reaction time3h, reaction temperature75℃and methanol to oil molar ratio25:1, the conversion rate of biodiesel was99.2%. After calcination at400℃and re-load of KOH, the regenerated catalyst was used to catalyze the transesterification of Jatropha oil, and the conversion rate of biodiesel was98%.KOH/Al-pillared bentonite was detected by SEM, XRD, and FTIR. Compared with Al-pillared bentonite, KOH/Al-pillared bentonite catalyst particle size was smaller, particle arrangement was more compact; and the sheet-shape objects were loaded the surface of catalyst. The characteristic peaks at31.7°,45.4°,56.6°belonged to alumina. The characteristic peaks at28.3°,40.6°,50.3°, and66.5°belonged to KAlSiO4. KOH/Al-pillared bentonite catalyst had large layer spacing, and the layer spacing was11.9nm. The reaction occurred between CO2and KOH, which an active component for the catalyst, and produced CO32-.KF/red as a catalyst catalyzed transesterification of Jatropha oil that had been esterified. The influence of KF load and transesterification reaction condition on the conversion rate of biodiesel was studied. It was found that KF/red mud catalyst with40%KF loading showed the optimum condition. When the transesterification was carried out under the optimum condition with catalyst amount7%, reaction time1h, reaction temperature75℃and methanol to oil molar ratio21:1, the conversion rate of biodiesel was92.2%. After calcinations at400℃and re-load of KF, the regenerated catalyst was used to catalyze the transesterification of Jatropha oil, and the conversion rate of biodiesel was91.4%.The catalyst was detected by SEM, XRD, and FTIR. It was showed that compared with red mud, KF/red mud catalyst particle surface was smoother, and the particle size was larger. The agglomeration was occurred between the particles. The characteristic peaks at31.2°,44.8°,and54.8°belonged to KFeF4. The reaction occurred between CO2and KOH, which produced from the reaction between KF and red mud, and produced CO32-. With KF loading process, the reaction had occurred between KF and Fe2O3that was main component in red mud, and produced KOH and KFeF4.