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首页> 外文期刊>Advanced Functional Materials >A Composite Formation Route to Well-Crystalline Manganese Oxide Nanocrystals: High Catalytic Activity of Manganate-Alumina Nanocomposites
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A Composite Formation Route to Well-Crystalline Manganese Oxide Nanocrystals: High Catalytic Activity of Manganate-Alumina Nanocomposites

机译：结晶态氧化锰纳米晶体的复合形成途径：锰-氧化铝纳米复合材料的高催化活性

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摘要

Manganese oxide nanocrystals are combined with aluminum oxide nanocrystals to improve their crystallinity via calcination without a significant increase of crystal size. A nanocomposite, consisting of two metal oxides, can be synthesized by the reaction between permanganate anions and aluminum oxyhydroxide keggin cations. The as-prepared manganese oxide-aluminum oxide nanocomposite is X-ray amorphous whereas heat-treatment gives rise to the crystallization of an α-MnO_2 phase at 600℃ and Mn_3O_4/Mn_2O_3 and γ-Al_2O_3 phases at 800 ℃. Electron microscopy and N_2 adsorption-desorption-isotherm analysis clearly demonstrate that the as-prepared nanocomposite is composed of a porous assembly of monodisperse primary particles with a size of~20 nm and a surface area of >410 m~2 g~(-1) Of particular interest is that the small particle size of the as-prepared nanocomposite is well-maintained up to 600 ℃, a result of the prevention of the growth of manganate grains through nanoscale mixing with alumina grains. The calcined nanocomposite shows very-high catalytic activity for the oxidation of cyclohexene with an extremely high conversion efficiency of >95% within 15 min. The present results show that the improvement of the crystallinity without significant crystal growth is very crucial for optimizing the catalytic activity of manganese oxide nanocrystals.
机译：氧化锰纳米晶体与氧化铝纳米晶体结合以通过煅烧改善其结晶度，而不会显着增加晶体尺寸。可以通过高锰酸根阴离子与氢氧化铝氢氧化物钾素阳离子之间的反应合成由两种金属氧化物组成的纳米复合材料。制备的氧化锰-氧化铝纳米复合材料为X射线非晶态，而热处理则导致600℃时α-MnO_2相和800℃时Mn_3O_4 / Mn_2O_3和γ-Al_2O_3相的结晶。电子显微镜和N_2吸附-解吸-等温线分析清楚地表明，所制备的纳米复合材料是由单分散一次颗粒的多孔组件组成的，颗粒大小约为20 nm，表面积大于410 m〜2 g〜（-1） ）特别令人感兴趣的是，所制得的纳米复合材料在600℃以下仍能保持较小的颗粒尺寸，这是通过与氧化铝颗粒进行纳米级混合来防止锰酸盐颗粒生长的结果。煅烧的纳米复合材料在15分钟内对环己烯的氧化表现出非常高的催化活性，转化率极高，> 95％。目前的结果表明，在不显着生长晶体的情况下提高结晶度对于优化氧化锰纳米晶体的催化活性至关重要。

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  • 来源
    《Advanced Functional Materials》 |2011年第12期|p.2301-2310|共10页
  • 作者

    Tae Woo Kim; Hana Yoo; In Young Kim; Hyung-Wook Ha; Ah Reum Han; Jong-San Chang; Ji Sun Lee; Seong-Ju Hwang;

  • 作者单位

    Department of Chemistry and Nano Sciences Ewha Womans University Seoul 120-750, Korea;

    Department of Chemistry and Nano Sciences Ewha Womans University Seoul 120-750, Korea;

    Department of Chemistry and Nano Sciences Ewha Womans University Seoul 120-750, Korea;

    Department of Chemistry and Nano Sciences Ewha Womans University Seoul 120-750, Korea;

    Department of Chemistry and Nano Sciences Ewha Womans University Seoul 120-750, Korea;

    Catalysis Center for Molecular Engineering Korea Research Institute of Chemical Technology (KRICT) P.O. Box, 107, Yuseong, Daejeon 305-600, Korea;

    Catalysis Center for Molecular Engineering Korea Research Institute of Chemical Technology (KRICT) P.O. Box, 107, Yuseong, Daejeon 305-600, Korea;

    Department of Chemistry and Nano Sciences Ewha Womans University Seoul 120-750, Korea;

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