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Soft X-ray spectroscopy studies of adsorption and reaction of CO in the presence of H2 over 6 nm MnO nanoparticles supported on mesoporous Co3O4

  • Author(s): Ralston, WT
  • Musselwhite, N
  • Kennedy, G
  • An, K
  • Horowitz, Y
  • Cordones, AA
  • Rude, B
  • Ahmed, M
  • Melaet, G
  • Alayoglu, S
  • et al.
Abstract

MnO nanoparticles (6 nm) were supported on mesoporous spinel Co O and studied using ambient pressure X-ray photoelectron spectroscopy (APXPS) and in situ X-ray absorption spectroscopy (XAS) during hydrogenation of CO. The nature and evolution of surface adsorbed species as well as the oxidation states of the metal oxide surfaces were evaluated under oxidizing, reducing, and H + CO (2:1) reaction atmospheres. From APXPS, MnO nanoparticle surfaces were found to be progressively reduced in H atmospheres with increasing temperature. Surface adsorbed CO was found to be formed at the expense of lattice O under H + CO reaction conditions. In situ XAS indicated that the dominant oxide species were Co(OH) , Co (II) oxides, MnO, and Mn O under reaction conditions. In situ XAS also indicated the formation of gas phase CO , the disappearance of lattice O, and the further reduction of Mn O to MnO upon prolonged reaction in H + CO. Mass spectroscopy measurements showed the formation of CO and hydrocarbons. The spent catalyst was investigated using scanning transmission X-ray microscopy and (scanning) transmission electron microscopy; the catalyst grains were found to be homogeneous. 3 4 2 2 2 2 3 4 2 3 4 2 2

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