(134e) DFT Predictions On the Kinetics and Bond Selectivity of Propane Activation On Palladium Oxide(101) Surface

Alkane activation on metal-based catalysts is of interest since it holds prospects as an energy source and in the production of value-added chemicals. Development of catalysts with high activity and precise selectivity is challenging due to the inertness of lower alkanes. In this talk, I will present results on dispersion-corrected density functional theory (DFT-D3) calculations of alkane activation on the PdO(101) surface. Dispersion corrections are found to improve binding energy predictions of alkane sigma-complexes on PdO(101), yielding values that compare well with experimental estimates. The calculations also predict a strong preference for propane to undergo primary C-H bond activation on PdO(101) which is consistent with experimental studies (90% of the chemisorbed C₃H₈ which reacts experimentally does so by primary C-H bond cleavage) but contrary to the thermodynamic preference for homolytic C-H bond cleavage (tertiary > secondary >  primary). Charge density analysis indicates that alkane activation on PdO(101) is heterolytic in nature and suggests that the high selectivity for primary C-H bond activation of C₃H₈ on PdO(101) results in part from greater polarization within the 1-propyl transition structures. We find that propane molecules also have a higher probability of initially populating molecular configurations in which primary C-H bonds interact strongly with the surface. I will also present results of a micro kinetic model used to evaluate the kinetic competition among reaction pathways available to adsorbed propane complexes and predict kinetic information that is comparable with experimental data.