锂-铝类水滑石催化大豆油酯交换制备生物柴油

Preparation of biodiesel via transesterification of soybean oil over lithium-aluminum hydrotalcite catalyst

采用共沉淀法制备了不同锂-铝比[n(Li)/n(Al)]的Li-Al类水滑石,经不同温度下焙烧得到复合氧化物;将复合氧化物作为大豆油与甲醇反应制备生物柴油的催化剂,考察了其对大豆油酯交换反应的催化性能.结果表明,n(Li)/n(Al)=13的类水滑石在400℃下焙烧得到的复合氧化物对大豆油酯交换反应具有极高的催化活性.在反应温度65℃、醇/油物质的量之比为15、催化剂用量为大豆油质量的0.5%条件下反应2h,生物柴油产率可达96.5%.与此同时,所制备的催化剂的回收再生性能良好,重复使用3次时生物柴油收率仍高达约90%.

A series of Li-Al hydrotalcite compounds with different n（Li）/n（Al） ratio was prepared via co-precipitation process.Resultant Li-Al hydrotalcite compounds were calcined at different temperatures to give their derivatives,Li-Al composite oxides.As-synthesized Li-Al composite oxides were used as solid alkali catalysts to prepare biodiesel via the transesterification of soybean oil and methanol,and the catalytic performance of the catalysts for the transesterification of soybean oil was investigated.It was found that the catalyst obtained by calcining Li-Al hydrotalcite sample with n（Li）/n（Al） = 13 at 400 ℃ had the best catalytic performance for the transesterification reaction of soybean oil.Biodiesel was harvested in a yield of 96.5% after the reactant system containing 0.5% catalyst and 15∶1 methanol plus soybean（molar ratio） was allowed to take part in transesterification reaction at 65 ℃ for 2 h.Moreover,the catalyst could be well recovered and reused,with the yield of biodiesel being as much as about 90% after three cycle of reuse.