Characterization and catalytic activity of unsupported nickel-rhenium catalysts modified by calcium oxide

Journal Article · Thu Jan 01 04:00:00 EST 1987 · J. Catal.; (United States)

DOI:https://doi.org/10.1016/0021-9517(87)90097-2· OSTI ID:5662543

Engels, S; Eick, J; Moerke, W; Maier, U; Boeszoermenyi, I; Matusek, K; Schay, Z; Guczi, L

Unsupported nickel-rhenium bimetallic catalysts have been prepared from a mixture of NH/sub 4/ReO/sub 4/ and nickel oxide containing CaO. It has been established that the total and metal surface areas as measured by X-ray diffraction, by the BET method and by CO chemisorption are enhanced by CaO addition compared to calcium-free samples. In addition, alloy formation is promoted by CaO, as indicated by ferromagnetic resonance (FMR) and X-ray diffraction measurements. X-Ray photoelectron spectroscopy reveals surface enrichment of rhenium and calcium abundance on the surface, particularly in heat treated samples. Sintering is retarded by the presence of CaO. The turnover frequencies for the dehydrogenation of cyclohexane, for the hydrogenation of benzene, and for the hydrogenolysis of ethane increase with increasing addition of Re to Ni up to the composition of 85 at.% Re-15 at.% Ni, followed by a fall for the pure rhenium catalyst. A remarkable effect of calcium addition is a strong suppression in the specific rate of ethane hydrogenolysis. For CO hydrogenation the TOF increases as the amount of nickel decreases and there is a simultaneous change in the olefin and C/sub 2//sup +/ selectivity. In the range between pure Ni and 85 at.% Ni-15 at.% Re the formation of higher hydrocarbons is slightly promoted whereas on the Re-rich samples a high methane selectivity can be observed due to the enhanced hydrogenation activity of rhenium.

• Research Organization: Technische Hochschule Carl Schorlemmer Leuna-Merseburg, East Germany
• OSTI ID: 5662543
• Journal Information: J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 103:1; ISSN JCTLA
• Country of Publication: United States
• Language: English

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ADDITIVES
ALKALINE EARTH METAL COMPOUNDS
ALKANES
ALKENES
AROMATICS
BENZENE
BIMETALS
CALCIUM COMPOUNDS
CALCIUM OXIDES
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYTIC EFFECTS
CATALYTIC REFORMING
CHALCOGENIDES
CHEMICAL PREPARATION
CHEMICAL REACTIONS
CHEMISORPTION
COHERENT SCATTERING
CYCLOALKANES
CYCLOHEXANE
DEHYDROGENATION
DIFFRACTION
ELECTRON SPECTROSCOPY
ELEMENTS
ETHANE
FERROMAGNETIC RESONANCE
HYDROCARBONS
HYDROGENATION
MAGNETIC RESONANCE
METALS
METHANATION
METHANE
NICKEL
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHOTOELECTRON SPECTROSCOPY
PROMOTERS
QUANTITY RATIO
REFORMER PROCESSES
RESONANCE
RHENIUM
SCATTERING
SEPARATION PROCESSES
SORPTION
SPECTROSCOPY
SURFACE AREA
SURFACE PROPERTIES
SYNTHESIS
TRANSITION ELEMENTS
X-RAY DIFFRACTION
X-RAY SPECTROSCOPY