1. Nanostructured MnO x as highly active catalyst for CO oxidation
- Author
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Frey, Krisztina, Iablokov, Viacheslav, Sáfrán, György, Osán, János, Sajó, István, Szukiewicz, Rafal, Chenakin, Sergey, and Kruse, Norbert
- Subjects
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CATALYTIC oxidation , *MANGANESE oxides , *CARBON dioxide , *STOICHIOMETRY , *TEMPERATURE effect , *SURFACE chemistry , *TRANSMISSION electron microscopy , *PHASE transitions - Abstract
Abstract: Non-stoichiometric Mn-oxides (MnO x and MnO y ) were prepared by temperature-programmed oxidation (TPO) of Mn-oxalates, MnC2O4·3H2O and MnC2O4·2H2O. Both oxides provide high specific surface areas (525m2 g−1 and 385m2 g−1, respectively) and identical CO oxidation reaction rates of 10−2 moleculesnm−2 s−1 (0.017μmolCO m−2 s−1) at 298K. A “spinodal” transformation of oxalates into oxides was observed by transmission electron microscopy (TEM). The quantitative evaluation of TPO and temperature-programmed reduction with CO allowed x-values of 1.61,…,1.67 to be determined for MnO x . The Mn oxidation state in MnO x was found to be 3.4±0.1 by X-ray absorption near-edge structure analysis and X-ray photoelectron spectroscopy. In accordance with the high specific surface area and mixed-type I/IV adsorption isotherms of MnO x , high resolution TEM demonstrated the occurrence of nested micro-rod features along with nanocrystalline particles in the endings of the rods. After CO oxidation MnO and Mn3O4 phases were able to be identified in the regions between rods. [Copyright &y& Elsevier]
- Published
- 2012
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