稀土基磷钨酸催化大豆油与甲醇合成生物柴油及其工艺优化

Optimization and Preparation of Biodiesel from Soybean Oil and Methanol Using Rare Earth Metal Ion-Exchanged Phosphotungstic Acid as Catalyst

以系列稀土改性磷钨酸为催化剂,大豆油与甲醇为原料进行酯交换反应制备生物柴油,考察各因素对生物柴油产率的影响,并通过响应面分析法优化制备工艺。研究表明,部分取代的稀土基磷钨酸催化剂具有较好的催化酯交换反应活性,其中Ce_(2/3)H_(1.0)PW_(12)O_(40)催化剂显示最好的生物柴油产率(94.4%)和重复使用性能,催化剂中Br?nsted酸中心和Lewis酸中心间的协同效应是其具有高催化性能的原因。响应面分析法优化生物柴油合成的最佳条件为:醇油物质的量比30∶1,催化剂量为大豆油质量的6.3%,反应时间20 h,反应温度148℃,该条件下生物柴油的产率为96.6%,该结果与模型预测值基本符合。实验结果对以植物油、高酸值餐饮废弃油脂等为原料制备生物柴油提供了一定的理论基础与实践经验。

A series of Brcnsted -Lewis acidic catalysts, namely MxH3-3xPW12O40（M = La, Ce, Pr, Nd, Sm; x = 1/3, 2/3, 1 ）, was prepared by incorporating rare earth metal cations as Lewis centers onto the superacidic tung- stophosphoric acid. The effects of various factors on the catalytic transesterification of soybean oil and methanol using MxH3 3xPW2040 as the catalysts were studied. The synthesis process of biodiesel was also optimized by response surface methodology （RSM）. The results showed that the partially ion - exchanged catalysts had satisfactory catalytic performances comparing with the pristine H3PW12O40. Among them, the Ce2/3H2 0PWlzOnocatalyst exhibited the best catalytic activity with superior biodiesel yield （94.4%） and an excellent durability. The high catalytic activity for the catalyst was found to invoke the Brcnsted -Lewis acid synergy. The optimum conditions were as follows： n （methanol ） ： n （ soybean oil） = 30： 1, the amount of catalyst to oil 6.3 %, reaction time 20 h and temperature 148℃. Under the optimized conditions, the yield of biodiesel reached 96.6%, which is in basic agreement with values predicted through the mathematical model. The experimental results provide a theoretical basis and practical experience for the preparation of biodiesel from the raw materials like the vegetable oil and the waste oil with high acid value.