CaO-MgO@CoFe2 O4磁性固体碱的制备及其大豆油酯交换反应催化性能

摘要

以草酸盐为前驱体采用两步法制备了一种以CaO-MgO作为活性组分,以CoFe2 O4作为磁核的磁性固体碱催化剂,并用于大豆油与甲醇的酯交换反应合成生物柴油。对制备的磁性固体碱催化剂进行了磁滞回线、X-射线衍射( XRD)、CO2-TPD及透射电镜( TEM)表征。考察了不同核壳物质的量比、焙烧温度、反应温度、反应时间、醇油物质的量比以及催化剂用量等因素对大豆油转化为生物柴油产率的影响。结果表明,采用核壳物质的量比为1：6、焙烧温度为700℃所制备的CaO-MgO@CoFe2 O4催化剂,当醇油物质的量比为12、催化剂用量为大豆油质量的1.0%时,在65℃下反应时间3 h,生物柴油收率高达97.1%。该催化剂具有较好的重复利用性能,重复利用四次后生物柴油的收率仍可达90%。%A magnetic core-shell CaO-MgO@CoFe2 O4 solid base was prepared with oxalates as the precursor through a two-step method, which was used as the catalyst for the transesterification of soybean oil to biodiesel with methanol. The CaO-MgO@CoFe2 O4 catalyst was characterized by magnetic hysteresis loop, X-ray diffraction ( XRD) , CO2-TPD and transmission electron microscopy ( TEM ); the effects of core-shell molar ratio, catalyst calcination temperature, reaction temperature, reaction time, methanol/oil molar ratio and catalyst amount on the yield of biodiesel were investigated. The results indicated that over the CaO-MgO@CoFe2 O4 catalyst with a core-shell molar ratio of 1:6 and calcined at 700 ℃, the biodiesel yield reaches 97 . 1% after conducting the transesterification reaction at 65℃ for 3 h, when the methanol/oil mol ratio is 12 and the amount of catalyst is 1. 0% by mass. The catalyst exhibits excellent reusability; the biodiesel yield remains above 90%after reusing for four cycles.