Gas-phase selective oxidation of cyclohexanol to cyclohexanone over Au/Mg1-xCuxCr2O4 catalysts: On the role of Cu doping

Yanan Gao, Emiel J.M. Hensen (Corresponding author)

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Abstract

The industrial production of cyclohexanone from cyclohexanol would benefit from a selective oxidation catalyst. Herein, Cu doping of MgCr2O4 supports for gold nanoparticles active in gas-phase oxidation of cyclohexanol was investigated. Mg1-xCuxCr2O4 exhibited spinel structures (x ≤ 0.25: MgCr2O4; x = 1: CuCr2O4) onto which 3–4 nm gold nanoparticles could be dispersed. Cu doping led to higher activity. During reaction, surface Cu2+ was reduced to Cu0, resulting in Au–Cu alloy formation. At low temperature, low-Cu-content catalysts (x ≤ 0.1) showed higher activity than high-Cu-content catalysts, likely because the Au–Cu alloy with highly diluted Cu was more active for the dehydrogenation step of cyclohexanol. However, Au/Mg0.99Cu0.01Cr2O4 and Au/Mg0.9Cu0.1Cr2O4 showed lower cyclohexanol conversion at high temperature than samples with high Cu content, because O2 activation involving Cu becomes rate-limiting. Stable cyclohexanol conversion and cyclohexanone selectivity were 99.1% and 90.2% (space-time yield of 266 gKetone gAu −1 h−1) for Au/Mg0.25Cu0.75Cr2O4 at 300 °C.

Original languageEnglish
Pages (from-to)218-230
Number of pages13
JournalJournal of Catalysis
Volume384
DOIs
Publication statusPublished - Apr 2020

Keywords

  • Cu doping
  • Cyclohexanone
  • Cyclohexnanol
  • Gold nanoparticles
  • Selective oxidation

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