The Studies On Transesterification Of Soybean Oil By Solid Acid And Base Catalysts

In the paper, WO₃/SnO₂ and CaO-Fe₂O₃ solid base catalysts were prepared and tested for soybean oil transesterification reaction with methanol. The reaction conditions including methanol/oil mole ratio, catalyst amount and reaction time, and the preparation conditions and preparation method, were studied to value how they affected the soybean oil conversions.The catalytic activity of recovered catalysts was also investigated.The SEM, IR, XRD and DSC-TG were employed to characterize the solid base catalysts.The experimental results showed that, for WO₃/SnO₂ solid base, the appreciate reaction conditions were: methanol/oil mole ratio of 30:1, catalyst amount of 5wt.%, reaction time of 5h, loading amount of 30wt.%W, calcination temperature 1173K, and the soybean oil conversion could reach 79.1%. under the above conditions. For CaO-Fe₂O₃ solid base catalyst, the appreciate conditions were: methanol/oil mole ratio 15:1, catalyst amount 4wt.%, reaction time 4h, Ca/Fe molar ratio of 1.5, calcination temperature 1073K, and the conversion could reach 92.63% under the above conditions.The SEM, IR, XRD and DSC-TGcharacterized results showed that the catalyst activity of WO₃/SnO₂ was relative to the state of W in the surface of catalyt activity center closey. The excessively enhancing calcination temperature or increasing loading amount of W will result in lots of WO₃ crystallites congregating on carrier, and consequently led to the decline of the catalytic activity. For CaO-Fe₂O₃ solid catalyt,catalytic activity of CaO-Fe₂O₃ was relative to the presence modality of Ca activity center closey. The excessively enhancing calcination temperature or increasing Ca/Fe molar ratio will result in lots of CaO crystallites congregating on carrier, and consequently led to the catalytic activity declining.The results of catalyst reusability experimental showed that with the increasing of reused times, the catalyst activity of WO₃/SnO₂ will be reduced gradually, and the soybean oil conversion could reach 54.3% when the catalyst was reused three times. In addition, for CaO-Fe₂O₃ catalyst, it is shown that the spent catalyst could be easily reactivated by calcinations at 1073K in air. Furthermore, there is no considerable change in the catalytic activity of the catalysts even after continuously used for 5 times.The obtained result shows that reuse of catalyst could give a high conversion of 90% upwards the identical reaction conditions as in the case of fresh catalysts.