Mechanism of alkali and alkaline earth catalyzed gasification of graphite by CO[sub 2] and H[sub 2]O studied by electron microscopy

Journal Article · Sat Oct 31 23:00:00 EST 1992 · Journal of Catalysis; (United States)

DOI:https://doi.org/10.1016/0021-9517(92)90003-Z· OSTI ID:5650323

Chen, S G; Yang, R T ^[1]

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1. State Univ. of New York, Buffalo, NY (United States)

The kinetics and mechanism of graphite gasification by CO[sub 2] and H[sub 2]O catalyzed by five alkali and alkaline earth metal catalysts are investigated by studying the monolayer channeling action on the basal plane of graphite. CO[sub 2] and H[sub 2]O are dissociatively chemisorbed by these catalysts, followed by diffusion of O atoms/ions to the edge carbon sites, where breakage of C-C bonds takes place to free CO. The C-C bond breakage is the rate-limiting step. The catalytic activities as measured by the turnover frequencies on the edge carbon sites follow the order K > Ba > Ca > Na > Li. The same catalytic mechanism and rate-limiting step operate in both channeling action and bulk reactions using mixed powders of carbon and catalysts. The results on channeling also indicate that the active intermediates are catalysts in the form of particles and clusters, and that the C-O-M (where M denotes metal) phenolate groups, although present in abundant amounts, are not the active intermediates. For very small particles, the surface free energy appears to play a role in lowering the amounts of CO[sub 2] and H[sub 2]O chemisorbed, hence decreasing the channeling rates. 55 refs., 4 figs., 1 tab.

• OSTI ID: 5650323
• Journal Information: Journal of Catalysis; (United States), Journal Name: Journal of Catalysis; (United States) Vol. 138:1; ISSN 0021-9517; ISSN JCTLA5
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400201* -- Chemical & Physicochemical Properties
ALKALI METAL COMPOUNDS
ALKALINE EARTH METAL COMPOUNDS
BARIUM COMPOUNDS
CALCIUM COMPOUNDS
CARBON
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CATALYSIS
CATALYSTS
CHALCOGENIDES
CHANNELING
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
CHEMISORPTION
ELECTRON MICROSCOPY
ELEMENTAL MINERALS
ELEMENTS
ENERGY
FREE ENERGY
GASIFICATION
GRAPHITE
HETEROGENEOUS CATALYSIS
HYDROGEN COMPOUNDS
KINETICS
LITHIUM COMPOUNDS
MICROSCOPY
MINERALS
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PARTICLES
PHYSICAL PROPERTIES
POTASSIUM COMPOUNDS
REACTION INTERMEDIATES
REACTION KINETICS
SEPARATION PROCESSES
SODIUM COMPOUNDS
SORPTION
THERMOCHEMICAL PROCESSES
THERMODYNAMIC PROPERTIES
WATER