Synthesis, Characterization, and Catalytic Properties of Hollow γ-Fe2O3 Spheres toward Liquid-Phase Oxidation Using Hydrogen Peroxide
Synthesis, Characterization, and Catalytic Properties of Hollow γ-Fe2O3 Spheres toward Liquid-Phase Oxidation Using Hydrogen Peroxide
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DOI：
10.1246/bcsj.20100130
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发表时间：
2010-09
影响因子：
4
通讯作者：
K. Mori;Isamu Tanimura;H. Yamashita
中科院分区：
文献类型：
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作者：
K. Mori;Isamu Tanimura;H. Yamashita
以羧基化聚苯乙烯微球为核模板，通过热处理和煅烧合成了空心γ-Fe 2 O3纳米球。采用红外光谱、氮气吸附-脱附、透射电镜、X射线衍射和铁K边XAFS等手段对材料进行了表征。空心γ-Fe 2 O3纳米球的粒径约为400-500 nm，由粒径约为10-20 nm的初级粒子组装而成。在较低的温度下，在氧气存在下煅烧后，复合颗粒发生了由磁铁矿（Fe 3 O 4）到磁赤铁矿（γ-Fe 2 O3）的相变。空心γ-Fe 2 O3作为一种高效的多相催化剂，用于过氧化氢（H2 O2）液相选择氧化1-苯乙醇的反应。结果表明，纳米γ-Fe 2 O3的催化活性和选择性均优于本体法制备的纳米γ-Fe 2 O3.通过外加永磁体可将空心γ-Fe 2 O3纳米球从反应混合物中回收，且废催化剂可循环使用，而其固有的催化能力没有任何明显损失。
Hollow γ-Fe 2 O 3 nanospheres were synthesized using carboxylated polystyrene spheres as a core template by thermal treatment followed by calcination. The obtained material was characterized by FT-IR, N 2 adsorption-desorption, TEM, XRD, and Fe K-edge XAFS measurements. The size of the hollow γ-Fe 2 O 3 nanospheres were about 400-500 nm, which was assembled from primary particles with a size of approximately 10-20 nm. The phase transition of the composed particles from magnetite (Fe 3 O 4 ) to maghemite (γ-Fe 2 O 3 ) was identified after calcination in the presence of O 2 at relatively low temperature. The hollow γ-Fe 2 O 3 acted as an efficient heterogeneous catalyst for the liquid-phase selective oxidation of 1-phenylethanol using hydrogen peroxide (H 2 O 2 ) as an oxidant. It exhibited enhanced catalytic activity compared to its bulk counterpart and also showed higher selectivity than nanosized γ-Fe 2 O 3 . Recovery of the hollow γ-Fe 2 O 3 nanospheres from the reaction mixture could be attained by applying an external permanent magnet, and the spent catalyst could be recycled without any appreciable loss of its inherent catalytic ability.