Understanding the mechanism(s) of ketone oxidation on VOx/γ-Al2O3

Ran Zhu, Bowei Liu, Siwen Wang, Xinlei Huang, Robson L. Schuarca, Wenlin He, Viktor J. Cybulskis, Jesse Q. Bond

Research output: Contribution to journalArticlepeer-review

Abstract

The oxidative scission of carbonyl compounds is of interest in the production of carboxylic acids, and homogeneously-catalyzed pathways have been well-studied in condensed media. The reaction can also be performed in the gas phase over solid oxides; however, mechanistic insights about heterogeneous pathways are sparse. To this end, we investigate the oxidative scission of 3-methyl-2-butanone over γ-Al2O3 and VOx/γ-Al2O3 using kinetic analysis and spectroscopic methods. We observe that the oxidative scission of 3-methyl-2-butanone can occur on reducible vanadium oxides and non-reducible aluminum oxides, and we consider the existence of separate pathways mediated by lattice oxygen and gas phase dioxygen. Fourier-transformed infrared (FTIR) and diffuse reflectance ultraviolet–visible (DR UV–Vis) spectra obtained under reaction conditions provide insights into the nature of surface species; the regimes where they form; and the degree of lattice reduction in those regimes. Based on these complementary insights, we propose a mechanism for the gas-phase oxidative scission of ketones on VOx/γ-Al2O3. We include elements of Mars-van Krevelen and Eley-Rideal pathways, and we consider the significance of acid-base and redox steps in facilitating the oxidative scission of ketones.

Original languageEnglish (US)
Pages (from-to)109-127
Number of pages19
JournalJournal of Catalysis
Volume404
DOIs
StatePublished - Dec 2021

Keywords

  • Eley-Rideal
  • Ketone oxidation
  • Mars-van Krevelen
  • Oxidation mechanism
  • Temperature programmed surface reaction
  • Vanadium oxide

ASJC Scopus subject areas

  • Catalysis
  • Physical and Theoretical Chemistry

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