Biodiesel Production from Jatropha Curcas, Waste Cooking, and Camelina Sativa Oils

Abstract

Process parameter evaluation and catalyst performance study was conducted for biodiesel production using jatropha curcas, waste cooking, and camelina sativa oils. Conversion of triglycerides to methyl esters involves esterification and/or transesterification, depending on the nature of the feedstock. A two-step transesterification process (acid esterification followed by alkali transesterification) was employed to produce biodiesel from high free fatty acids (FFA) in jatropha curcas and waste cooking oils, and a single-step transesterifcation process (alkali transesterifcation) was used for camelina sativa oil conversion. Catalyst selection is vital in transesterification process because it determines biodiesel yield and cost. Transesterification of jatropha curcas and waste cooking oil was optimized by using H2SO4 and ferric sulfate catalysts in the acid esterification step and a KOH catalyst in the alkali transesterification, respectively. Heterogeneous metal oxide catalysts including BaO, SrO, MgO, and CaO were used for the transesterification of camelina sativa oil. Jatropha curcas oil was observed to have yields in the range of 90−95%, with a maximum of 95% obtained at the following process conditions: acid esterification, methanol to oil molar ratio of 6:1, 0.5% of H2SO4, and 40 ± 5 °C; alkali tranesterification, methanol to oil molar ratio of 9:1, 2% of KOH, and 60 °C. Waste cooking oil yielded biodiesel in the range of 85−96%, with a maximum of 96% observed at the following optimized process conditions: 2 h reaction at 100 °C, methanol to oil molar ratio of 9:1, and 2% of a ferric sulfate catalyst. Comparative experiments on camelina sativa oil conversion showed that the most effective catalyst was BaO that showed >80% yield of camelina to biodiesel. Fuel properties of biodiesel produced from the three different feedstocks were determined and compared with the ASTM standards for biodiesel and petroleum diesel.