The Nature of the Isolated Gallium Active Center for Propane Dehydrogenation on Ga/SiO2

Viktor Cybulskis, Shankali U. Pradhan, Juan J. Lovón-Quintana, Adam S. Hock, Bo Hu, Guanghui Zhang, W. Nicholas Delgass, Fabio H. Ribeiro, Jeffrey T. Miller

Research output: Contribution to journalArticle

11 Scopus citations

Abstract

Abstract: Single-site Ga/SiO2 catalysts exhibit up to 99% C3H6 selectivity at 4% propane conversion with an initial rate of 5.4 × 10−4 (mole C3H6) (mole Ga)−1 s−1 during propane dehydrogenation (PDH) at 550 °C. Following pre-treatment in H2 at 550 °C, only four-coordinate, Ga3+–O Lewis acid sites are observed under reaction conditions. At 650 °C in H2, an additional isolated Ga site with lower Ga–O coordination (NGa−O < 4) is formed and leads to a 30% decrease in the initial PDH rate per total moles of Ga. The PDH rates are equivalent when normalized by the amount of surface, four-coordinate Ga3+–O, regardless of catalyst pre-treatment conditions, which indicates that these isolated Ga3+ centers are the catalytically relevant sites. Graphical Abstract: Isolated, Lewis acidic Ga3+ cations present as four-coordinate Ga3+–O centers exhibit up to 99% C3H6 selectivity during propane dehydrogenation (PDH) at 550 °C. An additional isolated Ga site with lower Ga–O coordination is formed during H2 treatment at elevated temperatures, but is inactive for PDH and reversibly decomposes under reaction conditions. [Figure not available: see fulltext.].

Original languageEnglish (US)
Pages (from-to)1252-1262
Number of pages11
JournalCatalysis Letters
Volume147
Issue number5
DOIs
StatePublished - Jan 1 2017
Externally publishedYes

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Keywords

  • Dehydrogenation
  • EXAFS
  • Heterogeneous catalysis
  • NEXAFS
  • XPS

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)

Cite this

Cybulskis, V., Pradhan, S. U., Lovón-Quintana, J. J., Hock, A. S., Hu, B., Zhang, G., Delgass, W. N., Ribeiro, F. H., & Miller, J. T. (2017). The Nature of the Isolated Gallium Active Center for Propane Dehydrogenation on Ga/SiO2. Catalysis Letters, 147(5), 1252-1262. https://doi.org/10.1007/s10562-017-2028-2