磁性催化剂Na_2O·SiO_2/Fe_3O_4的制备及其催化酯交换反应

Preparation of magnetic catalyst Na_2O·SiO_2/Fe_3O_4 and transesterification catalyzed by catalyst

以Na2SiO3为活性物质,以纳米Fe3O4为磁核制备磁性固体碱催化剂Na2O·SiO2/Fe3O4,通过正交实验,得到催化剂的最佳制备条件为:硅与铁的摩尔比2.5,晶化时间2h,煅烧温度350℃,煅烧时间2.5h,并通过震动样品磁强计(VSM)对催化剂的磁性进行表征。结果表明,所制备的催化剂Na2O·SiO2/Fe3O4具有较好的磁性和顺磁性,抗水性能优于传统均相碱催化剂;将其应用于棉籽油酯交换反应制备脂肪酸甲酯的最优工艺参数为:醇油摩尔比7:1,催化剂加入量5%,反应温度65℃,反应时间1h,搅拌速度400r/min,在此条件下,催化棉籽油酯交换反应转化率为99.6%,连续使用11次后活性仍在90%以上。

A novel magnetic solid base catalyst Na2O·SiO2/Fe3O4 was prepared with Fe3O4 nano-particles as magnetic core and Na2·SiO3 as active ingredient.The catalyst was used to catalyze transesterification reaction for fatty acid methyl esters（bio-diesel）from rude cotton seed oil.The optimal conditions of catalyst preparation and transesterification were confirmed by orthogonal experiments.The optimal conditions were Si/Fe molar ratio of 2.5,aging time of 2 h,calcination temperature of 350℃,calcination time of 2.5h.The catalyst was characterized with Vibrating Sample Maganetometer（VSM）.The results showed that prepared catalyst Na2O·SiO2/Fe3O4 had good specific saturation magnetization and paramagnetism and its water resistance was better than the traditional homogeneous based catalyst.The transesterification of cotton seed oil was catalyzed by the catalyst,and the optimal reaction conditions were methanol/oil molar ratio of 7：1,catalyst dosage of 5%,reaction time of 1 h,stirring speed of 400 r/min.The first transesterification rate was 99.6% and the catalytic activity exceeded 90% after 11 batches under the optimum conditions.