Biodiesel production from vegetable oil using heterogenous acid and alkali catalyst

• Published in: Fuel (Guildford) Vol. 89; no. 10; pp. 2939 - 2944
• Main Authors: Zhang, Junhua, Chen, Shangxing, Yang, Rui, Yan, Yuanyuan
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01.10.2010; Elsevier
• Subjects: Applied sciences; Biodiesel; Calcium oxide; Catalysts; Conversion; Energy; Energy. Thermal use of fuels; Esterification; Exact sciences and technology; Ferric sulfate; Fuels; Heterogeneous catalysis; Mathematical models; Optimization; Reaction time; Response surface methodology; Transesterification; Zanthoxylum; CaO; FFA; Heterogeneous catalysis; Calcium oxide; Ferric sulfate; ANOVA; ZSO; Response surface methodology; RSM; Biodiesel; Diesel fuel; Toxicity; Biofuel; Vegetable oil; Regression analysis; Transesterification; Sulfates; Reaction rate; Fatty acids; Esterification; Multiple regression; Corrosion; Reaction time; Catalyst; Methanol
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2010.05.009

Zanthoxylum bungeanum seed oil (ZSO) with high free fatty acids (FFA) can be used for biodiesel production by ferric sulfate-catalyzed esterification followed by transesterification using calcium oxide (CaO) as an alkaline catalyst. Acid value of ZSO with high FFA can be reduced to less than 2 mg KOH/g by one-step esterification with methanol-to-FFA molar ratio 40.91:1, ferric sulfate 9.75% (based on the weight of FFA), reaction temperature 95 °C and reaction time 2 h, which satisfies transesterification using an alkaline catalyst. The response surface methodology (RSM) was used to optimize the conditions for ZSO biodiesel production using CaO as a catalyst. A quadratic polynomial equation was obtained for biodiesel conversion by multiple regression analysis and verification experiments confirmed the validity of the predicted model. The optimum combination for transesterification was methanol-to-oil molar ratio 11.69:1, catalyst amount 2.52%, and reaction time 2.45 h. At this optimum condition, the conversion to biodiesel reached above 96%. This study provided a practical method to biodiesel production from raw feedstocks with high FFA with high reaction rate, less corrosion, less toxicity, and less environmental problems.