Performance, Structure, and Mechanism of ReOx-Pd/CeO2 Catalyst for Simultaneous Removal of Vicinal OH Groups with H2

Nobuhiko Ota, Masazumi Tamura, Yoshinao Nakagawa, Kazu Okumura, Keiichi Tomishige

Research output: Contribution to journalArticle

51 Citations (Scopus)

Abstract

The ceria-supported rhenium catalyst modified with palladium (ReOx-Pd/CeO2 (Re = 2 wt %, Pd/Re = 0.25)) is still the best catalyst for simultaneous hydrodeoxygenation. Higher Re loading amount decreased the activity. The simultaneous hydrodeoxygenation of cyclic vicinal diols occurs with high cis-stereoselectivity. ReOx-Pd/CeO2 catalysts were characterized by means of XRD, TEM, H2-TPR, XAFS, XPS, Raman, and DFT calculations. The Re species on ReOx-Pd/CeO2 (Re = 2 wt %, Pd/Re = 0.25) catalyst after reduction and after stoichiometric reaction of 1,2-hexanediol to 1-hexene were ReIV and ReVI, and the ReIV species were converted to ReVI through the stoichiometric reaction. The Re species on ReOx-Pd/CeO2 are proposed to be randomly located on the CeO2 surface, and probably only monomeric Re species have catalytic activity for simultaneous hydrodeoxygenation. This model can explain the higher activity of Re = 2 wt % catalyst than those of higher Re loading catalysts. The reaction is proposed to proceed by the tetra/hexavalent redox cycle of the Re center in the catalysis followed by hydrogenation.

Original languageEnglish
Pages (from-to)3213-3226
Number of pages14
JournalACS Catalysis
Volume6
Issue number5
DOIs
Publication statusPublished - 2016 May 6

Keywords

  • deoxydehydration
  • heterogeneous catalysis
  • hydrodeoxygenation
  • palladium
  • rhenium oxide

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)

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