SO_4~(2-)/ZrO_2/Fe_3O_4/TiO_2磁性固体酸催化剂的制备与性能

采用化学共沉淀法制备了SO_4~(2-)/ZrO_2/Fe_3O_4/TiO_2磁性固体酸,利用X射线衍射、示差扫描量热、M(o|¨)ssbauer谱、透射电子显微镜、NH_3-程序升温脱附、N_2吸附-脱附、磁滞回线等手段对磁性固体酸的结构与性质进行了表征。表征结果显示,磁性基质Fe_3O_4及TiO_2的引入有利于四方晶相ZrO_2(t)的稳定;ZrO_2晶体生长取向于ZrO_2(t)的(101)方向,(101)晶面间距为0.293 nm;M(o|¨)ssbauer谱中双峰的存在表明磁性基质Fe_3O_4的存在;在室温下磁性固体酸具有超顺磁性。以乙酸乙酯的合成为探针反应,考察了SO_4~(2-)/ZrO_2/Fe_3O_4/TiO_2磁性固体酸催化剂的催化性能,实验结果表明,外加磁场使酯化反应的醋酸转化率提高到92%。

Preparation and Properties of Nano Magnetic Solid Acid Catalyst SO_4~(2-)/ZrO_2/Fe_3O_4/TiO_2

Nano magnetic solid acids SO_4~(2-)/ZrO_2/Fe_3O_4/TiO_2 were prepared by co precipitation. Obtained samples were characterized by XRD, DSC, Mssbauer, TEM, NH_3 TPD,N_2 adsorption desorption and magnetic hysteresis loop. The introduction of TiO_2 and magnetic substrate Fe_3O_4 were beneficial to keep tetragonal crystalline structure of ZrO_2 from transferring to monoclinic form in calcination, ZrO_2 crystals grew along the direction of (101) crystal plane. The interplanar distance of ZrO_2(t) (101) plane were 0.293 nm. Mssbauer results revealed the existence of magnetic substrate Fe_3O_4 particles. Magnetic measurement showed superparamagnetism of solid acid catalyst at ambient temperature. Taking synthesis of ethyl acetate as probe reaction for evaluating the activity of nano magnetic solid acid SO_4~(2-)/ZrO_2/Fe_3O_4/TiO_2 catalyst, the conversion of acetic acid in the esterification mounted to 92% in external magnetic field and aggregation of nano magnetic solid acid catalyst was avoided.