Influence of Dioxygen on the Promotional Effect of Bi during Pt-Catalyzed Oxidation of 1,6-Hexanediol

Jiahan Xie, Benjamin Huang, Kehua Yin, Hien N. Pham, Raymond R. Unocic, Abhaya K. Datye, Robert J. Davis

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25 Scopus citations

Abstract

A series of carbon-supported, Bi-promoted Pt catalysts with various Bi/Pt atomic ratios was prepared by selectively depositing Bi on Pt nanoparticles. The catalysts were evaluated for 1,6-hexanediol oxidation activity in aqueous solvent under different dioxygen pressures. The rate of diol oxidation on the basis of Pt loading over a Bi-promoted catalyst was 3 times faster than that of an unpromoted Pt catalyst under 0.02 MPa of O2, whereas the unpromoted catalyst was more active than the promoted catalyst under 1 MPa of O2. After liquid-phase catalyst pretreatment and 1,6-hexanediol oxidation, migration of Bi on the carbon support was observed. The reaction order in O2 was 0 over Bi-promoted Pt/C in comparison to 0.75 over unpromoted Pt/C in the range of 0.02-0.2 MPa of O2. Under low O2 pressure, rate measurements in D2O instead of H2O solvent revealed a moderate kinetic isotope effect (rateH2O/rateD2O) on 1,6-hexanediol oxidation over Pt/C (KIE = 1.4), whereas a negligible effect was observed on Bi-Pt/C (KIE = 0.9), indicating that the promotional effect of Bi could be related to the formation of surface hydroxyl groups from the reaction of dioxygen and water. No significant change in product distribution or catalyst stability was observed with Bi promotion, regardless of the dioxygen pressure.

Original languageEnglish
Pages (from-to)4206-4217
Number of pages12
JournalACS Catalysis
Volume6
Issue number7
DOIs
StatePublished - Jul 1 2016

Keywords

  • Bi
  • Pt
  • alcohol oxidation
  • catalyst restructuring
  • dioxygen pressure
  • heterogeneous catalysts
  • isotope effect
  • promotional effect

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