K_2CO_3/γ-Al_2O_3催化连续双酯交换反应体系制备生物柴油

K_2CO_3/γ-Al_2O_3 catalysts were developed for the synthesis of biodiesel in continuous double transesterification reaction catalyst system

以γ-Al_2O_3为载体、K_2CO_3为活性组分,采用等体积浸渍法制备K_2CO_3/γ-Al_2O_3负载型固体碱,并以此为催化剂催化菜籽油-甲醇-碳酸二甲酯连续双酯交换反应制备生物柴油。考察并优化了催化剂制备条件及反应参数,结果表明,在反应温度65℃、油/酯/醇摩尔比1∶1∶8、K_2CO_3负载量60%、催化剂用量30%条件下反应30 min,粗生物柴油产率可达99.0%以上,与其他文献所报道的非均相固体碱催化剂相比,K_2CO_3/γ-Al_2O_3具有较高的催化活性。结果发现,K_2CO_3与γ-Al_2O_3发生相互作用生成强碱性物质是催化剂具有较高催化活性的主要原因;同时,对K_2CO_3/γ-Al_2O_3催化剂的重复性进行考察,发现将反应后的催化剂经过处理再焙烧后继续用于催化连续双酯交换反应,其粗生物柴油产率仍可达到85.0%以上。

The K2CO3/ γ-Al2O3 catalysts,developed for the synthesis of biodiesel from rapeseed oil-methanol-dimethyl carbonate continuous double transesterification,were prepared by impregnation method. Investigate and optimize the catalyst preparation conditions and reaction parameters. When the reaction temperature 65 ℃,the molar ratio of oil ∶ ester ∶ alcohol = 1 ∶ 1 ∶ 8,K2CO3 load was 60%,catalyst content of30% reaction 30 min,the biodiesel yield was 99. 0%,compared with other solid base catalysts reported in the literature,K2CO3/ γ-Al2O3 had higher catalytic activity. The result showed that the catalysts revealed that the increased basic property and catalytic activity of K2CO3/ γ-Al2O3 catalyst are attributed to the new species produced by the interaction between support γ-Al2O3 and K2CO3. The regenerate catalyst was reused in continuous double transesterification and the biodiesel yield can still be above 85. 0%.