Direct formation of acetate from the partial oxidation of ethylene on a Au/TiO2 catalyst

Isabel Xiaoye Green, Monica McEntee, Wenjie Tang, Matthew Neurock, John T. Yates

Research output: Contribution to journalArticlepeer-review

9 Scopus citations

Abstract

The partial oxidation of ethylene to form adsorbed acetate on a Au/TiO 2 catalyst at temperatures as low as 370 K is reported here using Fourier transform infrared (FTIR) spectroscopy, gas chromatography-mass spectrometry (GC-MS) and density functional theory (DFT) calculations. Ethylene reacts with oxygen on Au/TiO2 to produce acetate on the TiO 2 support as determined by the comparison with a blank TiO 2 and Au/SiO2 catalyst. As shown by DFT calculations, O2 dissociation occurs at the dual-perimeter Au-Ti4+ sites of Au/TiO2 catalysts. Surprising, no ethylene oxide on the catalyst surface or in the gas phase is detected by either FTIR or GC-MS techniques at temperatures up to 673 K. The reaction pathway to ethylene oxide involves a higher barrier (~1.0-1.5 eV) than the pathway for acetate formation (~0.1-0.6 eV). The rate-limiting step to form adsorbed acetate was found to be the protonation of the H2C*C(OH)O*intermediate to produce the bound acetic acid. The theoretical initial deuterium kinetic isotope effect is ~3 which is consistent with the experimental data. Graphical Abstract: [Figure not available: see fulltext.]

Original languageEnglish (US)
Pages (from-to)1512-1524
Number of pages13
JournalTopics in Catalysis
Volume56
Issue number15-17
DOIs
StatePublished - Nov 2013

Bibliographical note

Funding Information:
Acknowledgments We gratefully thank the DOE-Office of Basic Energy Sciences under grant number DE-FG02-09ER16080, as well as the XSEDE computing resources from Texas Advanced Computing Center and San Diego Supercomputer Center. We appreciate the generosity of Professor R. Zanella from UNAM who provided us the Au/ SiO2 sample. We also acknowledge two fellowships for Isabel Green and Monica McEntee from AES Corporation through the AES Graduate Fellowships in Energy Research Program at the University of Virginia.

Keywords

  • Acetate
  • Density functional theory
  • Deuterium kinetic isotope effect
  • Dual catalytic sites
  • Ethylene oxide

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