title: Propane σ-Complexes on PdO(101): Spectroscopic Evidence of the Selective Coordination and Activation of Primary C-H Bonds.
abstract: Achieving selective C-H bond cleavage is critical for developing catalytic processes that transform small alkanes to value-added products. The present study clarifies the molecular-level origin for an exceptionally strong preference for propane to dissociate on the crystalline PdO(101) surface via primary C-H bond cleavage. Using reflection absorption infrared spectroscopy (RAIRS) and density functional theory (DFT) calculations, we show that adsorbed propane σ-complexes preferentially adopt geometries on PdO(101) in which only primary C-H bonds datively interact with the surface Pd atoms at low propane coverages and are thus activated under typical catalytic reaction conditions. We show that a propane molecule achieves maximum stability on PdO(101) by adopting a bidentate geometry in which a H-Pd dative bond forms at each CH3 group. These results demonstrate that structural registry between the molecule and surface can strongly influence the selectivity of a metal oxide surface in activating alkane C-H bonds.
authors.affiliation: Department of Chemical Engineering, University of Florida, P.O. Box 116005, Gainesville, FL 36211 (USA).
authors.forename: Feng
authors.initials: F
authors.lastname: Zhang
authors.affiliation: William G. Lowrie Department of Chemical & Biomolecular Engineering, The Ohio State University, Columbus, OH 43210 (USA).
authors.forename: Li
authors.initials: L
authors.lastname: Pan
authors.affiliation: Department of Chemical Engineering, University of Florida, P.O. Box 116005, Gainesville, FL 36211 (USA).
authors.forename: Juhee
authors.initials: J
authors.lastname: Choi
authors.affiliation: Department of Chemical Engineering, University of Florida, P.O. Box 116005, Gainesville, FL 36211 (USA).
authors.forename: Vikram
authors.initials: V
authors.lastname: Mehar
authors.affiliation: Department of Chemical Engineering, University of Florida, P.O. Box 116005, Gainesville, FL 36211 (USA).
authors.forename: John T
authors.initials: JT
authors.lastname: Diulus
authors.affiliation: William G. Lowrie Department of Chemical & Biomolecular Engineering, The Ohio State University, Columbus, OH 43210 (USA).
authors.forename: Aravind
authors.initials: A
authors.lastname: Asthagiri
authors.affiliation: Department of Chemical Engineering, University of Florida, P.O. Box 116005, Gainesville, FL 36211 (USA). weaver@che.ufl.edu.
authors.forename: Jason F
authors.initials: JF
authors.lastname: Weaver
keywords: CH bond activation; alkane; heterogeneous catalysis; palladium; palladium oxide