Enhancement of Catalytic Activities of Octahedral Molecular Sieve Manganese Oxide for Total and Preferential CO Oxidation through Vanadium Ion Framework Substitution

Authors

  • Homer C. Genuino,

    1. Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269-3060 (USA), Fax: (+1) 860-486-2981
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  • Yongtao Meng,

    1. Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269-3060 (USA), Fax: (+1) 860-486-2981
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  • Dayton T. Horvath,

    1. Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269-3060 (USA), Fax: (+1) 860-486-2981
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  • Chung-Hao Kuo,

    1. Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269-3060 (USA), Fax: (+1) 860-486-2981
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  • Mohammad S. Seraji,

    1. Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269-3060 (USA), Fax: (+1) 860-486-2981
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  • Prof. Aimee M. Morey,

    1. Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269-3060 (USA), Fax: (+1) 860-486-2981
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  • Prof. Raymond L. Joesten,

    1. Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269-3060 (USA), Fax: (+1) 860-486-2981
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  • Prof. Steven L. Suib

    Corresponding author
    1. Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269-3060 (USA), Fax: (+1) 860-486-2981
    • Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, Connecticut 06269-3060 (USA), Fax: (+1) 860-486-2981
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Abstract

High-valent vanadium ions were substituted into the synthetic cryptomelane manganese oxide (K-OMS-2) framework through a simple and low-cost reflux method and investigated for total and preferential catalytic oxidation of carbon monoxide. Substitutional doping of V5+ resulted in materials with modified composition, morphology, thermal stability; and textural, redox, and catalytic properties. The catalytic activity increased with V concentration until an optimum amount (≈10 % V incorporated) was reached, beyond that a structural “crash point” was observed, resulting in a material with low crystallinity, nanosphere morphology, and reduced catalytic activity. An increase in O2 concentration in the feed gas resulted in an increase in conversion over 10% V K-OMS-2. This most active catalyst was deactivated by moisture only at low temperatures and showed better tolerance than undoped K-OMS-2. This catalyst also preferentially oxidized CO to CO2 from 25 °C to 120 °C in large amounts of H2 under dry conditions, without significantly affecting CO conversion. The doped catalyst also showed stable activity and selectivity in long-run experiments. The mobility and lability of surface oxygen, formation of hydroxyl groups, and enhanced surface redox properties promoted by V doping were strongly correlated with the enhancement of catalytic activities of K-OMS-2 nanomaterials.

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