用于生物柴油清洁生产的磁性固体催化剂CaO/MgO/Fe_3O_4

制备了具有磁性和催化活性的双功能催化剂CaO/MgO/Fe3O4,用于催化花生油酯交换制备生物柴油的清洁生产过程。对CaO/MgO/Fe3O4进行了XRD、TEM、FT-IR和磁性等表征分析,探讨了CaO/MgO/Fe3O4催化剂的重复利用性能。结果表明,用Mg(Ac)2溶液等体积浸渍磁性基质Fe3O4,在N2气氛中600℃焙烧2 h,可得到具有磁性的载体5%MgO/Fe3O4;再用Ca(Ac)2溶液等体积浸渍MgO/Fe3O4,并在N2气氛中700℃煅烧,得到具有磁性且催化活性较高的催化剂10%CaO/MgO/Fe3O4。该催化剂具有核壳结构,磁核平均直径约为35 nm。在催化剂用量10%,醇油摩尔比12∶1,反应温度65℃,反应2 h的条件下酯交换转化率可达90%以上。在磁场的吸引下该催化剂能快速与反应体系分离,催化剂回收率达90%。但CaO/MgO/Fe3O4重复利用性能较差,其原因是在搅拌反应过程中催化活性组分逐渐从催化剂上脱落所致。

A magnetic solid catalyst of CaO/MgO/Fe3O4 for production of clean biodiesel

A novel solid base catalyst, CaO/MgO/Fe₃O₄ with magnetism used for production of clean biodiesel, was prepared and characterized by X-ray diffraction, transmission electron microscope, infrared spectrum and magnetism analysis. The catalytic activities of the fresh and the reused catalysts for the transesterification of peanut oil with methanol to produce biodiesel were investigated. The magnetic support of MgO/Fe₃O₄ with MgO loading of 5% was obtained by the magnetic matrix Fe₃O₄ dipped in Mg(Ac)₂ aqueous solution and then calcined at 600℃ in N₂. And CaO/MgO/Fe₃O₄ with CaO loading of 10% was prepared by MgO/Fe₃O₄ impregnated in Ca(Ac)₂ aqueous solution and further calcined at 700℃ in N₂. The particle of CaO/MgO/Fe₃O₄ was shell-core structure with the core mean diameter of 35nm. The results show that CaO/MgO/Fe₃O₄ has higher catalytic activity for transesterification reaction and could be separated easily from the reaction products in magnetic field. Both the conversion of peanut oil and recovery of the catalyst are above 90% under the conditions of atmospheric pressure, 65℃ for 2h, methanol/oil mol ratio of 12, and catalyst dosage (catalyst/oil) of 10%. The falling off of CaO from CaO/MgO/Fe₃O₄ during stirring reaction process was speculated as one of the reasons for the lower activity of the reused catalyst.