Alumina-supported manganese catalysts for soot combustion prepared by thermal decomposition of KMnO4

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Title: Alumina-supported manganese catalysts for soot combustion prepared by thermal decomposition of KMnO4
Authors: Becerra, María Eugenia | Arias, Nayda Patricia | Giraldo, Óscar Hernán | López Suárez, Franz Edwin | Illán-Gómez, María José | Bueno López, Agustín
Research Group/s: Materiales Carbonosos y Medio Ambiente
Center, Department or Service: Universidad de Alicante. Departamento de Química Inorgánica
Keywords: Soot | Manganese catalyst | Supported catalyst | NOx | Birnessite | Cryptomelane
Knowledge Area: Química Inorgánica
Issue Date: 11-Sep-2012
Publisher: MDPI
Citation: Catalysts. 2012, 2: 352-367. doi:10.3390/catal2030352
Abstract: Alumina-supported manganese catalysts with cryptomelane and/or birnessite structure have been prepared using a simple method based on the thermal decomposition of potassium permanganate. The samples have been characterized by XRD, FTIR, TGA, DSC, N2 adsorption at −196 °C, SEM, H2-TPR and XPS, and their catalytic activity for soot combustion has been tested and compared to that of a reference Pt/alumina catalyst. The thermal decomposition of alumina-supported KMnO4 yields a mixture of supported birnessite and potassium manganate which is the most effective, among those prepared, to lower the soot combustion temperature. However, this material is not useful for soot combustion because the accelerating effect is not based on a catalytic process but on the oxidation of soot by potassium manganate. A suitable soot combustion catalyst is obtained after potassium manganate is removed by water washing, yielding only the birnessite phase on the γ-Al2O3 support. This birnessite phase can be transformed into cryptomelane by calcination at 600 °C. These two samples, γ-Al2O3-supported birnessite and cryptomelane are suitable catalysts for soot combustion in NOx/O2 mixtures, as their catalytic activity is based on the NO2-assited mechanism, that is, both catalysts accelerate the oxidation of NO to NO2 and NO2 promotes soot oxidation. The soot combustion temperatures obtained with these birnessite/cryptomelane alumina-supported catalysts are similar to that obtained with the reference Pt/alumina catalyst.
Sponsor: The authors thank to Spanish government (MICINN project CTQ2009-07475), DIMA (Dirección de Investigaciones) and Laboratorio de Magnetismo y Materiales Avanzados (Universidad Nacional de Colombia, Sede Manizales) and Vicerrectoría de Investigaciones de la Universidad de Caldas for the financial support.
ISSN: 2073-4344
DOI: 10.3390/catal2030352
Language: eng
Type: info:eu-repo/semantics/article
Rights: © 2012 by the authors; licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution license (
Peer Review: si
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Appears in Collections:INV - MCMA - Artículos de Revistas

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