Propylene hydrogenation and propane dehydrogenation by a single-site Zn2+ on silica catalyst

Neil M. Schweitzer, Bo Hu, Ujjal Das, Hacksung Kim, Jeffrey Greeley, Larry A. Curtiss, Peter C Stair, Jeffrey T. Miller, Adam S. Hock

Research output: Contribution to journalArticle

83 Citations (Scopus)

Abstract

This study reports the highly selective (more than 95%) dehydrogenation of propane to propylene as well as the reverse hydrogenation reaction by silica-supported single-site Zn(II) catalyst. The catalyst is thermally stable at dehydrogenation temperature (550 °C and above), and catalytic byproducts are small. In situ UV-resonance Raman, XANES, and EXAFS spectra reveal that tetrahedrally coordinated Zn(II) ions are chemisorbed into the strained three-membered siloxane rings on the amorphous silica surface. Under reaction conditions, the Zn(II) ion loses one Zn-O bond, resulting in a coordinatively unsaturated, 3-coordinate active center. The infrared spectrum of adsorbed pyridine indicates that these are Lewis acid sites. Theoretical calculations based on hybrid density functional theory suggest that the catalyst activates H-H and C-H bonds by a nonredox (metal) mechanism consisting of heterolytic cleavage of C-H bonds, in contrast with the homolytic mechanisms such as oxidative addition/reductive elimination pathways. The computed minority catalytic pathway consists of undesired C-C bond cleavage at Zn(II) site, follows a slightly different mechanism, and has a significantly higher activation energy barrier. These mechanisms are consistent with the high olefin selectivity observed for single-site Zn(II) on SiO2.

Original languageEnglish
Pages (from-to)1091-1098
Number of pages8
JournalACS Catalysis
Volume4
Issue number4
DOIs
Publication statusPublished - Apr 4 2014

Fingerprint

Propane
Dehydrogenation
Silicon Dioxide
Hydrogenation
Propylene
Silica
Catalysts
Ions
Siloxanes
Lewis Acids
Energy barriers
Alkenes
Pyridine
Olefins
Density functional theory
Byproducts
Activation energy
Metals
Infrared radiation
Acids

Keywords

  • heterogeneous Zn catalysis
  • Lewis Acid hydrogenation/dehydrogenation catalysis
  • propane dehydrogenation
  • propylene hydrogenation
  • single-site catalysts

ASJC Scopus subject areas

  • Catalysis

Cite this

Schweitzer, N. M., Hu, B., Das, U., Kim, H., Greeley, J., Curtiss, L. A., ... Hock, A. S. (2014). Propylene hydrogenation and propane dehydrogenation by a single-site Zn2+ on silica catalyst. ACS Catalysis, 4(4), 1091-1098. https://doi.org/10.1021/cs401116p

Propylene hydrogenation and propane dehydrogenation by a single-site Zn2+ on silica catalyst. / Schweitzer, Neil M.; Hu, Bo; Das, Ujjal; Kim, Hacksung; Greeley, Jeffrey; Curtiss, Larry A.; Stair, Peter C; Miller, Jeffrey T.; Hock, Adam S.

In: ACS Catalysis, Vol. 4, No. 4, 04.04.2014, p. 1091-1098.

Research output: Contribution to journalArticle

Schweitzer, NM, Hu, B, Das, U, Kim, H, Greeley, J, Curtiss, LA, Stair, PC, Miller, JT & Hock, AS 2014, 'Propylene hydrogenation and propane dehydrogenation by a single-site Zn2+ on silica catalyst', ACS Catalysis, vol. 4, no. 4, pp. 1091-1098. https://doi.org/10.1021/cs401116p
Schweitzer NM, Hu B, Das U, Kim H, Greeley J, Curtiss LA et al. Propylene hydrogenation and propane dehydrogenation by a single-site Zn2+ on silica catalyst. ACS Catalysis. 2014 Apr 4;4(4):1091-1098. https://doi.org/10.1021/cs401116p
Schweitzer, Neil M. ; Hu, Bo ; Das, Ujjal ; Kim, Hacksung ; Greeley, Jeffrey ; Curtiss, Larry A. ; Stair, Peter C ; Miller, Jeffrey T. ; Hock, Adam S. / Propylene hydrogenation and propane dehydrogenation by a single-site Zn2+ on silica catalyst. In: ACS Catalysis. 2014 ; Vol. 4, No. 4. pp. 1091-1098.
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