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SiO_2/(γ-Fe_2O_3-SiO_2)磁性催化剂载体的制备 被引量:10
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作者 王松威 徐盛明 +1 位作者 陈崧哲 徐景明 《中国有色金属学报》 EI CAS CSCD 北大核心 2005年第11期1761-1765,共5页
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:... 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. 展开更多
关键词 Γ-FE2O3 磁性催化剂载体 热稳定性 包覆
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Magnetically recyclable Pd/γ-AlOOH@Fe_3O_4 catalysts and their catalytic performance for the Heck coupling reaction 被引量:5
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作者 YANG Hao JI ShengFu +2 位作者 LIU XueFei ZHANG DanNi SHI Da 《Science China Chemistry》 SCIE EI CAS 2014年第6期866-872,共7页
Novel magnetically recyclable Pd/γ-AlOOH@Fe3O4 catalysts were prepared using γ-AlOOH@Fe3O4 as a magnetic supporter and nano-Pd particles as the active catalytic component.The structure of the catalysts was character... Novel magnetically recyclable Pd/γ-AlOOH@Fe3O4 catalysts were prepared using γ-AlOOH@Fe3O4 as a magnetic supporter and nano-Pd particles as the active catalytic component.The structure of the catalysts was characterized by X-ray diffraction(XRD),transmission electron microscopy(TEM),N2 adsorption-desorption,and a vibration sample magnetometer(VSM).The catalytic activity and recyclability for the Heck coupling reaction were investigated.Results showed that the magnetic γ-AlOOH@Fe3O4 possessed a core-shell structure,as well as that the nano-Pd particles were 6–8 nm and had been well dispersed in the γ-AlOOH shell.In the Heck coupling reactions,the magnetic Pd/γ-AlOOH@Fe3O4 catalysts exhibited good catalytic activity and recyclability.For the(0.021 mol%)Pd/γ-AlOOH@Fe3O4 catalyst,the bromobenzene conversion and product yield reached about 100%and 96.3%,respectively,under a 120°C reaction temperature and 12 h reaction time.After being recycled 8 times,the conversion of bromobenzene and the recovery of the catalyst were about 90%and 93%,respectively.The nano-Pd particles were kept well dispersed in the used Pd/γ-AlOOH@Fe3O4 catalyst. 展开更多
关键词 magnetic Pd/γ-AlOOH@Fe3O4 Heck reaction RECYCLABLE
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