Highly Selective Oxidation of Ethyl Lactate to Ethyl Pyruvate Catalyzed by Mesoporous Vanadia-Titania

Wei Zhang, Giada Innocenti, Paula Oulego, Vitaly Gitis, Haihong Wu, Bernd Ensing, Fabrizio Cavani, Gadi Rothenberg, N. Raveendran Shiju

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

The direct oxidative dehydrogenation of lactates with molecular oxygen is a "greener" alternative for producing pyruvates. Here we report a one-pot synthesis of mesoporous vanadia-titania (VTN), acting as highly efficient and recyclable catalysts for the conversion of ethyl lactate to ethyl pyruvate. These VTN materials feature high surface areas, large pore volumes, and high densities of isolated vanadium species, which can expose the active sites and facilitate the mass transport. In comparison to homogeneous vanadium complexes and VOx/TiO2 prepared by impregnation, the meso-VTN catalysts showed superior activity, selectivity, and stability in the aerobic oxidation of ethyl lactate to ethyl pyruvate. We also studied the effect of various vanadium precursors, which revealed that the vanadium-induced phase transition of meso-VTN from anatase to rutile depends strongly on the vanadium precursor. NH4VO3 was found to be the optimal vanadium precursor, forming more monomeric vanadium species. V4+ as the major valence state was incorporated into the lattice of the NH4VO3-derived VTN material, yielding more V4+-O-Ti bonds in the anatase-dominant structure. In situ DRIFT spectroscopy and density functional theory calculations show that V4+-O-Ti bonds are responsible for the dissociation of ethyl lactate over VTN catalysts and for further activation of the deprotonation of β-hydrogen. Molecular oxygen can replenish the surface oxygen to regenerate the V4+-O-Ti bonds.

Original languageEnglish
Pages (from-to)2365-2374
Number of pages10
JournalACS Catalysis
Volume8
Issue number3
DOIs
StatePublished - 2 Mar 2018

Keywords

  • DFT
  • biomass conversion
  • heterogeneous catalysis
  • in situ DRIFTS
  • mesoporous materials

ASJC Scopus subject areas

  • Catalysis
  • Chemistry (all)

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