Methanation of CO/sub 2/ on supported rhodium catalyst

Journal Article · Wed Apr 01 04:00:00 EST 1981 · J. Catal.; (United States)

OSTI ID:6152744

Solymosi, F; Erdoehelyi, A; Bansagi, T

The synthesis of methane from CO/sub 2/ and H/sub 2/ was investigated on supported Rh catalysts. The adsorbed species present on the catalysts were characterized by infrared spectroscopy. The hydrogenation of CO/sub 2/ on Rh/Al/sub 2/O/sub 3/ occurred at a measurable rate above 443/sup 0/K, yielding exclusively methane. The rate of methane formation on Rh/Al/sub 2/O/sub 3/ is described by the expression N/sub CH/sub 4// = 2.69 x 10/sup 6/ exp(-16.200/RT) P/sub H/sub 2///sup 0/ /sup 61/.P/sub CO/sub 2///sup 0/ /sup 26/. From a comparison of the specific activities of Rh/Al/sub 2/O/sub 3/ in the H/sub 2/ + CO/sub 2/ and H/sub 2/ + CO reactions it appears that the hydrogenation of CO/sub 2/ occurs much faster than that of CO. The support exerted a marked influence on the specific activity of Rh. The most effective support was TiO/sub 2/ and the least effective one SiO/sub 2/. Infrared spectroscopic measurements revealed that linearly bonded CO (perturbed by hydrogen adsorbed on the same Rh atom) and adsorbed formate species were present on the catalyst surface during the reaction. Evidence is presented to show that the surface formate is located not on the Rh, but rather on the support. The formation of surface C was also detected. Its amount slightly increased during the conditioning period and also with temperature elevation. It is proposed that the important steps in CH/sub 4/ formation are the dissociation of CO/sub 2/ promoted by adsorbed hydrogen, the subsequent dissociation of CO into reactive surface carbon, and hydrogenation of the latter. The possible reasons for the different methanation rates of CO/sub 2/ and CO are discussed.

• Research Organization: The University, Szeged, Hungary
• OSTI ID: 6152744
• Journal Information: J. Catal.; (United States), Journal Name: J. Catal.; (United States) Vol. 68:2; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

090121* -- Hydrocarbon Fuels-- Chemical Synthesis-- (1976-1989)
10 SYNTHETIC FUELS
ALKANES
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CARBON COMPOUNDS
CARBON MONOXIDE
CARBON OXIDES
CATALYST SUPPORTS
CATALYSTS
CATALYTIC EFFECTS
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
ELEMENTS
GAS YIELDS
HIGH TEMPERATURE
HYDROCARBONS
KINETICS
METALS
METHANATION
METHANE
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
REACTION KINETICS
REFRACTORY METALS
RHODIUM
SYNTHESIS
TITANIUM COMPOUNDS
TITANIUM OXIDES
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
YIELDS