摘要
以共沉淀法制备了纳米Fe_3O_4,考察了制备条件对纳米Fe_3O_4结构的影响。最佳制备条件为:总铁盐浓度0.10～0.25 mol/L、n(Fe^(2+)):n(Fe^(3+)):n(OH^-)=1.5:2.0:12.0、反应温度30℃。以正硅酸乙酯及PVP-DB-171(聚乙烯吡咯烷酮-乙烯基三甲氧基硅烷)为改性剂合成了具有核壳结构的表面聚合物改性的磁性载体PVP-DB-171/SiO_2/Fe_3O_4,进一步制备了磁性负载纳米钌催化剂。分析表明,所得粒子的结构是以面心尖晶石结构Fe_3O_4为核,菲晶态SiO_2为壳,纳米钌高度分散在磁性载体的表面。该粒子能很好地分散在有机溶剂中,可用磁分离实现固液分离。以甲苯的液相催化加氢反应为模型,评价了磁性负载钌催化剂的催化性能。在100℃及4.0 MPa氢压条件下,催化剂的转化频率可达5 591,磁分离后,催化剂可循环使用。
The magnetic nano catalysts have attracted more attention due to the novel properties of high dispersion and easy recirculation. The nano Fe3O4 was prepared through a co-precipitation method. The effects of reaction conditions on the structure of the nano Fe3O4 have been investigated and the optimal reaction conditions have been found as follows： total iron concentration is in the range of 0.10 mol/L to 0.25 mol/L, the mole ratio of （Fe^2＋） ： （Fe^3＋） ： （OH^-） is 1.5 ： 2.0 ： 12.0, and temperature is 30℃. The surface polymer modified nano support PVP-DB-171/SiO2/Fe3O4 has been prepared using tetraethyl silicate and PVP-DB-171 as modifier, and further used to support the nano ruthenium catalyst. The obtained catalyst was characterized by FT-IR, X-ray diffraction, SEM and TEM. The results showed that the cores are spinel Fe3O5 particles and unformed SiO2 as shells and the nano ruthenium particles are dispersed on the surface. The particles are highly dispersed in organic solvents and can be separated by magnetic field. The catalytic activity of the magnetic SiO2/Fe3O4 supported nano ruthenium particle was evaluated by the hydrogenation of toluene as a model reaction. At 100℃ and 4.0 MPa pressure of H2, the catalyst turnover frequency （TOF） was up to 5 591. After separation by magnetic field, the catalyst can be reused eight times without losing the activity.
出处
《精细石油化工》
CAS
CSCD
北大核心
2009年第1期4-9,共6页
Speciality Petrochemicals
基金
河北省教育厅百名优秀创新人才支持计划的基金。
关键词
磁性纳米粒子
核壳结构
钌催化剂
催化氢化
回收
magnetic nano particles
core-shell structure
ruthenium catalyst
catalytic hydrogenation
recirculation
