Redox behavior of ruthenium in zeolite Y

Journal Article · Thu Jul 16 04:00:00 EDT 1987 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100299a020· OSTI ID:6037071

Shoemaker, R; Apple, T

The /sup 129/Xe NMR of xenon gas sorbed in ruthenium-exchanged Y zeolites has been combined with volumetric oxidation/reduction studies and transmission electron microscopy to characterize the state of ruthenium at various stages of catalyst treatment. Upon ion exchange the majority of the Ru occupies the faujasite supercages and is highly dispersed. Initial exposure to hydrogen at room temperature causes nearly complete reduction of Ru/sup 3 +/ to Ru/sup 0/. Protons formed by the heterolytic cleavage of H/sub 2/ during the reduction process become the charge compensating cations. Exposure of the reduced catalyst to oxygen results in the quantitative oxidation of Ru to RuO/sub 2/ at temperatures up to 625 K, but no detectable migration of the ruthenium species accompanies this oxidation. Subsequent high-temperature rereductions in hydrogen atmospheres cause progressive migration of the ruthenium to the exterior of the zeolite crystals, forming larger metal particles which are difficult to reoxidize. The degree of migration is dependent upon the severity and the duration of the reduction. All detectable metal migrations occur as reduced metal species. High-temperature evacuation (725 K) of a reduced Ru-Na-Y zeolite causes sintering of the ruthenium and migration of the metal to the exterior of the faujasite cages. Oxidized ruthenium species do not migrate when evacuated at high temperature. Transmission electron microscopy measurements confirm that the migration of the ruthenium which was indicated by the xenon NMR results is to the exterior of the zeolite crystals.

• Research Organization: Univ. of Nebraska, Lincoln
• OSTI ID: 6037071
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 91:15; ISSN JPCHA
• Country of Publication: United States
• Language: English

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CATALYSTS
CHEMICAL REACTIONS
DATA
DAYS LIVING RADIOISOTOPES
ELECTRON MICROSCOPY
ELEMENTS
EVEN-ODD NUCLEI
EXPERIMENTAL DATA
HIGH TEMPERATURE
HYDROGEN
INFORMATION
INORGANIC ION EXCHANGERS
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ISOMERIC TRANSITION ISOTOPES
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MAGNETIC RESONANCE
MATERIALS
METALS
MICROSCOPY
MINERALS
NMR SPECTRA
NONMETALS
NUCLEAR MAGNETIC RESONANCE
NUCLEI
NUMERICAL DATA
OXYGEN
PLATINUM METALS
RADIOISOTOPES
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RUTHENIUM
SPECTRA
STABLE ISOTOPES
TRANSITION ELEMENTS
TRANSMISSION ELECTRON MICROSCOPY
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ZEOLITES