Preparation of biodiesel from pistacia chinensis bunge seed oil produced by two-phase solvent extraction

The preparation of biodiesel from pistacia chinensis bunge (PCB) seed oil produced by two-phase solvent extraction (TSE) was studied. The results show that the optimal extraction conditions are 50g samples, ethanol/iso-hexane volume ratio 50∶50 and the total volume of 300mL at 40℃ with duration of 30min. Under these conditions，the extraction rate of PCB seed oil could achieve 99.5%, and the free fatty acid (FFA) and water contents of PCB seed oil are reduced to 0.37% and 0.046%， respectively. This meets the requirement of alkali-catalyzed transesterification. After the TSE process of PCB seed，the investigations were carried out on transesterification of methanol with oil-iso-hexane solution coming from TSE process in the presence of Li₂O/MgO as solid base catalyst. The influences of weight ratio of iso-hexane to PCB seed oil，alkali catalyst amount，reaction temperature, molar ratio of methanol to oil and reaction time on PCB seed oil conversion were investigated separately. The fatty acid methyl ester content could achieve 98.1% using 2.0% (catalyst/oil weight ratio) solid base catalyst at 65℃ and 3h，2∶1 weight ratio of iso-hexane/oil and 9∶1 mole ratio of methanol/oil. The fatty acid methyl ester content remains 90% after the solid base catalyst was reused ten times. The results indicates that the catalyst of Li₂O/MgO has a higher activity and stability.