Aerobic oxidation of aqueous ethanol using heterogeneous gold catalysts: Efficient routes to acetic acid and ethyl acetate

Betina Jørgensen, Sofie Egholm Christiansen, M.L.D. Thomsen, Christina Hviid Christensen

Research output: Contribution to journalJournal articleResearchpeer-review

Abstract

The aerobic oxidation of aqueous ethanol to produce acetic acid and ethyl acetate was studied using heterogeneous gold catalysts. Comparing the performance of Au/MgAl2O4 and Au/TiO2 showed that these two catalysts exhibited similar performance in the reaction. By proper selection of the reaction conditions, yields of 90-95% of acetic acid could be achieved at moderate temperatures and pressures. Based on our findings, a reaction pathway for the catalytic oxidation of ethanol via acetaldehyde to acetic acid is proposed, and the rate-determining step (RDS) in the mechanism is found to be the (possibly oxygen-assisted) dehydrogenation of ethanol to produce acetaldehyde. It also is concluded that most of the CO2 formed as a byproduct in the reaction results from the absorbed intermediate in the dehydrogenation of ethanol to produce acetaldehyde. By varying the amount of water in the reaction mixture, the possibilities for producing ethyl acetate by the aerobic oxidation of ethanol is also studied. At low ethanol concentrations, the main product is acetic acid; at concentrations >60 wt%, it is ethyl acetate.
Original languageEnglish
JournalJournal of Catalysis
Volume251
Issue number2
Pages (from-to)332-337
ISSN0021-9517
DOIs
Publication statusPublished - 2007

Keywords

  • acetic acid
  • heterogeneous catalysis
  • bioethanol
  • aerobic oxidation
  • ethyl acetate
  • gold

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