CO sub 2 hydrogenation over nickel/zirconia catalysts from amorphous precursors: On the mechanism of methane formation

Journal Article · Thu Aug 08 00:00:00 EDT 1991 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100169a049· OSTI ID:7081045

Schild, C; Wokaun, A ^[1]; Koeppel, R A; Baiker, A ^[2]

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1. Univ. of Bayreuth (Germany)
2. Swiss Federal Inst. of Tech., Zentrum (Switzerland)

An amorphous Ni{sub 64}Zr{sub 36} alloy is used as a precursor for a carbon dioxide hydrogenation catalyst. Upon exposure to CO{sub 2} hydrogenation conditions, the glassy metal is partly transformed into crystalline metallic nickel particles and less well-ordered zirconium dioxide. A conventional Ni/ZrO{sub 2} catalyst, which was synthesized by coprecipitation and calcination of the amorphous precipitate, served as a reference. The as-prepared catalyst exhibits a very similar catalytic behavior to the alloy-derived catalyst. The structural and chemical changes are characterized by gas adsorption, X-ray diffraction, and thermal analysis. In CO{sub 2} hydrogenations over these catalysts, methane is almost exclusively produced, and traces of ethane are formed besides, as evidenced by gas chromatography. To study the origins of this selectivity behavior, in situ diffuse reflectance FTIR spectroscopy has been applied. Surface species in carbon dioxide as well as carbon monoxide hydrogenation reactions are correlated with the formation of gas-phase products. CO{sub 2}/H{sub 2} mixtures rapidly yield surface formate as the immediate precursor of the methane product on the coprecipitated catalyst. Doubly and singly bound adsorbed CO is detected besides; doubly bound CO is observed to originate from surface formate. In CO/H{sub 2} reactions, higher saturated hydrocarbons are produced besides methane. The formation of these products proceeds from singly bound adsorbed CO via a dissociative mechanism. The respective hydrogenation steps are discussed in detail in a corresponding reaction scheme.

• OSTI ID: 7081045
• Journal Information: Journal of Physical Chemistry; (United States), Vol. 95:16; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
10 SYNTHETIC FUELS
CARBON DIOXIDE
METHANATION
NICKEL
CATALYTIC EFFECTS
ZIRCONIUM OXIDES
ABSORPTION SPECTROSCOPY
CATALYST SUPPORTS
CATALYSTS
EXPERIMENTAL DATA
GAS CHROMATOGRAPHY
HYDROGENATION
INFRARED SPECTRA
METHANE
THERMAL ANALYSIS
X-RAY DIFFRACTION
ALKANES
CARBON COMPOUNDS
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
CHROMATOGRAPHY
COHERENT SCATTERING
DATA
DIFFRACTION
ELEMENTS
HYDROCARBONS
INFORMATION
METALS
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
SCATTERING
SEPARATION PROCESSES
SPECTRA
SPECTROSCOPY
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
ZIRCONIUM COMPOUNDS
010408* - Coal
Lignite
& Peat- C1 Processes- (1987-)
100200 - Synthetic Fuels- Production- (1990-)