Phase bahavior of palladium-silver particles supported on silica

Journal Article · Thu Apr 08 04:00:00 EDT 1993 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100116a021· OSTI ID:6163224

Phillips, J ^[1]; Auroux, A; Bergeret, G; Massardier, J; Renouprez, A ^[2]

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1. Pennsylvania State Univ., University Park (United States)
2. CNRS, Villeurbanne (France)

In this work, the structure as a function of treatment of palladium-silver catalyst particles supported on silica is explored using X-ray diffraction, kinetic probes, calorimetry, and temperature-programmed desorption. It is shown that following oxidation at a high temperature (675 K), the particles consist of an outer shell of PdO with an inner core of metallic silver. This structure undergoes a number of transformations under reaction conditions (butadiene hydrogenation) at low (300 K) temperatures. Initially, the outer shell of PdO reduces to palladium metal, and an alloy layer begins to form at the center. After a period of several hours, the entire particle becomes a true alloy. Following oxidation at a lower temperature (475 K), the particle consists of an outer layer of silver oxide and an inner core of palladium metal. The outer shell reduces under reaction conditions, but an alloy never forms. The potential application of these findings to other noble metal/noble metal systems is discussed. 26 refs., 7 figs., 1 tab.

• OSTI ID: 6163224
• Journal Information: Journal of Physical Chemistry; (United States), Journal Name: Journal of Physical Chemistry; (United States) Vol. 97:14; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

02 PETROLEUM
020400* -- Petroleum-- Processing
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201 -- Chemical & Physicochemical Properties
BUTADIENE
CALORIMETRY
CATALYST SUPPORTS
CATALYSTS
CHALCOGENIDES
CHEMICAL REACTIONS
COHERENT SCATTERING
DESORPTION
DIENES
DIFFRACTION
ELEMENTS
HYDROCARBONS
HYDROGENATION
METALS
MINERALS
ORGANIC COMPOUNDS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PALLADIUM
PALLADIUM COMPOUNDS
PALLADIUM OXIDES
PLATINUM METALS
POLYENES
PROCESSING
REDOX REACTIONS
REFINING
SCATTERING
SILICA
SILICON COMPOUNDS
SILICON OXIDES
SILVER
SORPTION
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
X-RAY DIFFRACTION