SiO_2/(γ-Fe_2O_3-SiO_2)磁性催化剂载体的制备  

Preparation of SiO_2/(γ-Fe_2O_3-SiO_2) magnetic catalyst carrier

作　　者：王松威[1] 徐盛明[1] 陈崧哲[1] 徐景明[1] 

机构地区：[1]清华大学核能与新能源技术研究院,北京100084

出　　处：《中国有色金属学报》2005年第11期1761-1765,共5页The Chinese Journal of Nonferrous Metals

基　　金：国家自然科学基金资助项目(50274045)

摘　　要：采用溶胶-凝胶法制备了具有高热稳定性的γ-Fe2O3-SiO2复合材料,并在其表面进行SiO2包覆,获得了纳米尺寸磁核的单分散球形SiO2/(γ-Fe2O3-SiO2)颗粒.X射线衍射分析、热重差热分析、扫描电镜、透射电镜以及振动样品磁强计等实验结果说明:Fe2O3-SiO2复合物经过700℃以上温度煅烧30 min后才出现γ-Fe2O3晶相,更高温度或者更长的煅烧时间将导致γ-Fe2O3向α-Fe2O3的转变;经SiO2包覆后得到的SiO2/(γ-Fe2O3-SiO2)为粒径均匀的单分散球形颗粒,颗粒尺寸在150～200 nm左右,内部核心为γ-Fe2O3颗粒,外层则被严密的SiO2包裹.通过将纯Fe3O4粉外层直接包覆SiO2做对比实验表明,SiO2/(γ-Fe2O3-SiO2)具有更加优异的磁性能,是一种优良的催化剂磁性载体.Fe2O3-SiO2 composite was prepared with sol-gel method. SiO2 / （γ-Fe2O3-SiO2 ） magnetic catalyst carriers were obtained by coating composite with silica. These obtained samples were characterized by XRD, TG-DTA, TEM, SEM and VSM. The effects of processing temperature, time and initial dosage of iron nitrate on the properties of Fe2O3-SiO2 were studied. The results show that, after calcined at 700 ℃ for 30 min, the composite oxide containing γ-Fe2O3 phase is secured. While further increase of the processing temperature （〉800℃ ） or time results in the formation of α-Fe2O3 phase. SEM and TEM analyses show that the SiO2/（γ-Fe2O3-SiO2） sample is of nanosized, monodisperse spherical particles with size of 150 - 200 nm. which are well coated by amorphous SiO2 layer. The VSM data exhibit that SiO2/（γ-Fe2O3-SiO2 ） has much better magnetic properties than SiO2/Fe3O4. Such nanocomposites are very promising in application as magnetic catalyst carriers and sorbent carriers.

关 键 词：Γ-FE2O3 磁性催化剂载体 热稳定性 包覆 

分 类 号：TQ13[化学工程—无机化工]