Carbon Monoxide Oxidation Catalysed by Exotemplated Manganese Oxides
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Carbon Monoxide Oxidation Catalysed by Exotemplated Manganese Oxides ´ rfa˜o S. A. C. Carabineiro • S. S. T. Bastos • J. J. M. O M. F. R. Pereira • J. J. Delgado • J. L. Figueiredo
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Received: 12 November 2009 / Accepted: 3 December 2009 / Published online: 22 December 2009 Ó Springer Science+Business Media, LLC 2009
Abstract Manganese oxides were synthesized by exotemplating using carbon materials as templates. The catalytic activity for CO oxidation was found to be mainly related with the availability of the lattice oxygen that can react with CO. Loading the materials with Au increased the activity only for the activated carbon exotemplated samples. This is due to the Au low particle size found for these samples, in contrast with others prepared with carbon xerogels. Keywords Manganese oxides Exotemplating Gold Carbon monoxide Oxidation
S. A. C. Carabineiro (&) S. S. T. Bastos ´ rfa˜o M. F. R. Pereira J. L. Figueiredo J. J. M. O Laborato´rio de Cata´lise e Materiais (LCM), Laborato´rio Associado LSRE/LCM, Departamento de Engenharia Quı´mica, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal e-mail: [email protected] S. S. T. Bastos e-mail: [email protected] ´ rfa˜o J. J. M. O e-mail: [email protected] M. F. R. Pereira e-mail: [email protected] J. L. Figueiredo e-mail: [email protected] J. J. Delgado Departamento de Ciencia de los Materiales e Ingenierı´a Metalu´rgica y Quı´mica Inorga´nica, Facultad de Ciencias, Universidad de Ca´diz, Campus Rio San Pedro, 11510 Puerto Real, Ca´diz, Spain e-mail: [email protected]
1 Introduction Highly porous materials have been recently synthesised by templating methods [1–7]. When the template has structural pores in which another solid is created and is able to provide a scaffold for the synthesis, it is called an ‘‘exotemplate’’ [3]. Generally, the empty spaces of the porous template are filled with a precursor solution. After calcination, the template is removed and a material with the structure of its pores is obtained. Carbon templates are attractive due to their high surface areas and porosities, low cost and because they are easily removed by combustion. This approach has been successfully used for the synthesis of many high surface area metal and mixed metal oxides (e.g. Al2O3, CeO2, Cr2O3, Fe2O3, MgO, TiO2) using activated carbon [1–3, 5] activated carbon fibers [3, 5] carbon nanotubes [8] and carbon aerogels [4] as templates. Mesoporous silica KIT-6 was also recently used as a hard template for the synthesis of three-dimensional mesoporous metal oxides (e.g. CeO2, Co3O4, Cr2O3, CuO, Fe2O3, b-MnO2, Mn2O3, Mn3O4, NiO) [6]. In a previous paper, our group reported on the synthesis of manganese oxides by exotemplating, using carbon materials with different textural properties and surface chemistries as templates, namely activated carbon and carbon xerogel [7]. These exotemplated materials were then used as catalysts for the oxidation of volatile organic compounds (namely ethanol) [7]. In the present work,
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