Adsorbate-Induced Structural Evolution of Pd Catalyst for Selective Hydrogenation of Acetylene

Yanan Liu, Fengzhi Fu, Alan McCue* (Corresponding Author), Wilm Jones, Deming Rao, Junting Feng* (Corresponding Author), Yufei He, Dianqing Li* (Corresponding Author)

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

7 Citations (Scopus)

Abstract

This work describes the transformation of Pd species under reaction conditions to control the reactivity of heterogeneous catalysts, in which the real active sites for hydrogenation differ from simple Pd sites on a carbon nanofiber. Specifically, in the presence of C2H2/C2H4/H2 reaction mixtures, a permeable amorphous hydrocarbon overlayer is formed with simultaneous insertion of carbon atoms into the Pd lattice that drives the formation of low-coordinated Pd-carbide, thus providing more reactive Pd-Csub@Clayer sites (Csub: subsurface carbon; Clayer: carbon layer on the surface). The combination of these surface and subsurface effects hinders Pd-hydride, weakens ethylene adsorption confirmed by density functional theory (DFT) calculation, and thus improves catalytic behavior for selective hydrogenation of acetylene (93% ethylene selectivity at 100% conversion) with long-term stability. In the absence of hydrogen, a denser more crystalline overlayer is formed with severely restricted permeability, resulting in significantly lower activity. Moreover, by X-ray absorption spectroscopy (XAS) and in situ X-ray diffraction (XRD), it is demonstrated that different active sites dominate this catalytic reaction depending on the choice of adsorbate and exposure temperature. This work represents an alternative and arguably a simpler manner to design more reactive catalytic sites with the characteristics of long-term stability and facile preparation, which would enable promising industrial applications.

Original languageEnglish
Pages (from-to)15048–15059
Number of pages12
JournalACS Catalysis
Volume10
Issue number24
Early online date7 Dec 2020
DOIs
Publication statusPublished - 18 Dec 2020

Keywords

  • Adsorbate induced
  • structural evolution
  • PD carbide
  • permeable carbon layer
  • selective acetylene hydrogenation
  • Pd-carbide
  • adsorbate-induced

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