Research ArticlePHYSICAL SCIENCES

Catalysis beyond frontier molecular orbitals: Selectivity in partial hydrogenation of multi-unsaturated hydrocarbons on metal catalysts

See allHide authors and affiliations

Science Advances  26 Jul 2017:
Vol. 3, no. 7, e1700939
DOI: 10.1126/sciadv.1700939
  • Fig. 1 Experimental observations of hydrogenation products.

    The evolution of two possible reaction products upon hydrogenation of isophorone (left) and acrolein (right) over Pd nanoparticles supported on the model Fe3O4/Pt(111) oxide film. Experimental details are given in the text. a.u., arbitrary units.

  • Fig. 2 Two alternative reaction pathways for isophorone on different metal surfaces.

    (A and B) Structure and molecular orbitals for the isolated isophorone molecule. (C) Structures of isophorone adsorbed on transition metal surfaces. (D) Molecular orbital density of states (MODOS) projected on the free isophorone HOMO−1, HOMO, and LUMO orbitals for isophorone on the Pd(111) surface (top) and Au(111) surface (bottom). The zero of energy corresponds to the Fermi level, and the d-band center of the clean Pd(111) surface is located at −2.11 eV. (E) Side view of the electron density difference upon isophorone adsorption on Pd(111) and Au(111) at their equilibrium adsorption structures. The values of the isosurface 0.04 and 0.015 Å−3 were used for the former and the latter. Cyan and purple indicate electron depletion and accumulation, respectively. The computed projected occupation of selected molecular orbitals near the Fermi level is also shown in this plot.

  • Fig. 3 IR and NEXAFS spectra of isophorone on Pd(III).

    (A) Experimental and theoretical IR spectra of gas-phase and surface-adsorbed isophorone on Pd(111). The experimental spectra were measured at 120 K, and the calculated anharmonic IR spectra for isophorone on Pd(111) were obtained on the basis of the relaxed structures using the PBE + vdWsurf method. str., stretching; def., deformation. (B) NEXAFS experimental spectra of the isophorone/Pd(111) system obtained at different polarization of the x-ray beam with respect to the Pd(111) surface at 120 K. ML, monolayer.

  • Fig. 4 Structure and electronic properties of acrolein.

    (A) Structure and molecular orbitals for the isolated acrolein molecule. (B) Structure of acrolein adsorbed on the Pd(111) surface. (C) MODOS projected on the free acrolein HOMO−1, HOMO, and LUMO orbitals for the adsorption system. The zero of energy corresponds to the Fermi level. (D) Side view of the electron density difference upon acrolein adsorption on Pd(111) at its equilibrium adsorption structure, using the value of the isosurface 0.04 Å−3. Cyan and purple indicate electron depletion and accumulation, respectively. The computed projected occupation of selected molecular orbitals near the Fermi level is also shown in this plot.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/7/e1700939/DC1

    Supplementary Text

    fig. S1. Structure and electronic properties of 1-butene.

    fig. S2. Hydrogenation pathways of isophorone on Pd(111).

    fig. S3. Adsorption structures of isophorone on Pd(111).

    fig. S4. MODOS of isophorone on metal surfaces.

    fig. S5. MODOS of acrolein on metal surfaces.

    fig. S6. Coadsorption structure of isophorone on Pd(111).

    fig. S7. Isophorone on Pd(111) at high coverage.

  • Supplementary Materials

    This PDF file includes:

    • Supplementary Text
    • fig. S1. Structure and electronic properties of 1-butene.
    • fig. S2. Hydrogenation pathways of isophorone on Pd(111).
    • fig. S3. Adsorption structures of isophorone on Pd(111).
    • fig. S4. MODOS of isophorone on metal surfaces.
    • fig. S5. MODOS of acrolein on metal surfaces.
    • fig. S6. Coadsorption structure of isophorone on Pd(111).
    • fig. S7. Isophorone on Pd(111) at high coverage.

    Download PDF

    Files in this Data Supplement:

Stay Connected to Science Advances

Navigate This Article