title: The irreversible formation of palladium carbide during hydrogenation of 1-pentyne over silica-supported palladium nanoparticles: in situ Pd K and L3 edge XAS.
abstract: The catalytically active phase of silica-supported palladium catalysts in the selective and non-selective hydrogenation of 1-pentyne was determined using in situ X-ray absorption spectroscopy at the Pd K and L(3) edges. Upon exposure to alkyne, a palladium carbide-like phase rapidly forms, which prevents hydrogen to diffuse into the bulk of the nano-sized particles. Both selective and non-selective hydrogenation occur over carbided particles. The palladium carbide-like phase is stable under reaction conditions and only partially decomposes under high hydrogen partial pressure. Non-selective hydrogenation to pentane is not indicative of hydride formation. The palladium carbide phase was detected in the EXAFS analysis and the K edge XANES showed representative features.
authors.affiliation: ETH Zurich, Institute for Chemical and Bioengineering, 8093 Zurich, Switzerland.
authors.forename: Min Wei
authors.initials: MW
authors.lastname: Tew
authors.forename: Maarten
authors.initials: M
authors.lastname: Nachtegaal
authors.forename: Markus
authors.initials: M
authors.lastname: Janousch
authors.forename: Thomas
authors.initials: T
authors.lastname: Huthwelker
authors.forename: Jeroen A
authors.initials: JA
authors.lastname: van Bokhoven
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D002244:Carbon / Q000737:chemistry*; D006865:Hydrogenation; D053768:Metal Nanoparticles / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D056928:X-Ray Absorption Spectroscopy
chemical_list: D000480:Alkynes; D010165:Palladium; D002244:Carbon; D012822:Silicon Dioxide