Nanostructured MnO x as highly active catalyst for CO oxidation

Krisztina Frey, Viacheslav Iablokov, György Sáfrán, János Osán, István Sajó, Rafal Szukiewicz, Sergey Chenakin, Norbert Kruse

Research output: Contribution to journalArticle

62 Citations (Scopus)

Abstract

Non-stoichiometric Mn-oxides (MnO x and MnO y) were prepared by temperature-programmed oxidation (TPO) of Mn-oxalates, MnC 2O 4·3H 2O and MnC 2O 4·2H 2O. Both oxides provide high specific surface areas (525 m 2 g -1 and 385 m 2 g -1, respectively) and identical CO oxidation reaction rates of 10 -2 molecules nm -2 s -1 (0.017 μmol CO m -2 s -1) at 298 K. 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 Mn 3O 4 phases were able to be identified in the regions between rods.

Original languageEnglish
Pages (from-to)30-36
Number of pages7
JournalJournal of Catalysis
Volume287
DOIs
Publication statusPublished - Mar 1 2012

Keywords

  • CO oxidation
  • Manganese oxide
  • Micro-rods and nanocrystals
  • XANES
  • XPS

ASJC Scopus subject areas

  • Catalysis
  • Physical and Theoretical Chemistry

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