Methane oxidation over alumina-supported noble metal catalysts with and without cerium additives

Journal Article · Sun Dec 01 04:00:00 EST 1991 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1016/0021-9517(91)90149-X· OSTI ID:7168699

Oh, S H; Mitchell, P J; Siewert, R M ^[1]

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1. General Motors Research Labs., Warren, MI (United States)

Laboratory reactor experiments have been conducted to evaluate alumina-supported noble metal catalysts, both in the presence and absence of cerium additives, for their effectiveness in the catalytic oxidation of methane under conditions likely to be encountered in natural-gas vehicle exhaust. Under oxidizing conditions, all of the catalysts promoted the complete oxidation of methane to CO{sub 2} and H{sub 2}O, with the methane oxidation activity ranking given by Pd > Rh > Pt in the absence of Ce and by Rh > Pd {approximately}Pt in the presence of Ce. Under reducing conditions, methane oxidation produced substantial amounts of CO and H{sub 2} as the principal partial oxidation products. In the absence of Ce, the methane oxidation activity decreases in the order Pd > Rh > Pt, with the tendency to form CO decreasing in the order Rh > Pd > Pt. The activity ranking for methane conversion in reducing feedstreams was not affected by the presence of Ce; however, the addition of Ce to the Pt/Al{sub 2}O{sub 3} catalysts almost completely suppressed the formation of the partial oxidation product CO. At a fixed temperature of {approximately}550C, the methane conversion over each of the noble metal catalysts goes through a maximum as the feedstream concentration of O{sub 2} is varied. The data suggest that O{sub 2} inhibits the CH{sub 4} oxidation under oxidizing conditions by excluding the more weakly adsorbed species, CH{sub 4}, from the active sites. Also, methane oxidation experiments in the presence of CO in the feed showed that the methane conversion characteristics of the noble metal catalysts are little affected by the CO.

• OSTI ID: 7168699
• Journal Information: Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 132:2; ISSN 0021-9517; ISSN JCTLA
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
030700* -- Natural Gas-- Waste Management
33 ADVANCED PROPULSION SYSTEMS
330704 -- Emission Control-- Hydrocarbons
54 ENVIRONMENTAL SCIENCES
540120 -- Environment
Atmospheric-- Chemicals Monitoring & Transport-- (1990-)
AIR POLLUTION CONTROL
ALKANES
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
BENCH-SCALE EXPERIMENTS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON MONOXIDE
CARBON OXIDES
CATALYST SUPPORTS
CATALYSTS
CATALYTIC EFFECTS
CERIUM
CHALCOGENIDES
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
COMPARATIVE EVALUATIONS
CONTROL
ELEMENTS
ENERGY SOURCES
EVALUATION
FLUIDS
FOSSIL FUELS
FUEL GAS
FUEL SUBSTITUTION
FUELS
GAS FUELS
GASES
HYDROCARBONS
KINETICS
METALS
METHANE
NATURAL GAS
ORGANIC COMPOUNDS
OXIDATION
OXIDES
OXYGEN COMPOUNDS
PALLADIUM
PLATINUM
PLATINUM METALS
POLLUTION CONTROL
PROMOTERS
RARE EARTHS
REACTION KINETICS
RHODIUM
TRANSITION ELEMENTS
VAPORS
WATER VAPOR