Origin of Electronic Modification of Platinum in a Pt3V Alloy and Its Consequences for Propane Dehydrogenation Catalysis

We demonstrate the synthesis of a Pt3V alloy and Pt/Pt3V core/shell catalysts, which are highly selective for propane dehydrogenation. The selectivity is a result of the Pt3V intermetallic phase, which was characterized by in situ synchrotron XRD and XAS. Formation of a continuous alloy surface layer 2-3 atomic layers thick was sufficient to obtain identical catalytic properties between a core-shell and full alloy catalyst, which demonstrates the length scale over which electronic effects pertinent to dehydrogenation act. Electronic characterization of the alloy phase was investigated by using DFT, XPS, XANES, and RIXS, all of which show a change in the energy of the filled and unfilled Pt 5d states resulting from Pt-V bonding. The electronic modification leads to a change in the most stable binding site of hydrocarbon fragments, which bind to V containing ensembles despite the presence of 3-fold Pt ensembles in Pt3V. In addition, electronic modification destabilizes deeply dehydrogenated species thought to be responsible for hydrogenolysis and coke formation.