Mechanism of catalyzed graphite oxidation by monolayer channeling and monolayer edge recession

Journal Article · Fri Sep 01 00:00:00 EDT 1989 · Journal of Catalysis; (USA)

DOI:https://doi.org/10.1016/0021-9517(89)90146-2· OSTI ID:6960654

Goethel, P J; Yang, R T ^[1]

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1. State Univ. of New York, Buffalo (USA)

Monolayer channeling (i.e., channeling at one graphite layer depth) on the basal plane of graphite is revealed for catalysts in the graphite-oxygen reaction by employing gold decoration/TEM. Rates and mechanisms of monolayer channeling have been studied for Pt, Cu, V, and V{sub 2}O{sub 5}. The breakage of carbon-carbon bonds at the Pt and edge graphite interface is the rate-limiting step for Pt-catalyzed oxidation. An oxygen transfer mechanism appears to be operative in the vanadium-catalyzed oxidation, and the rate-limiting step is the oxidation of the surface of the particle which is in the reduced state of V{sub 6}O{sub 13}. The rate-limiting step for the copper-catalyzed reaction is a step occurring at the interface between the catalyst and edge graphite, either by the breakage of carbon-carbon bonds or the oxidation of edge carbon by CuO. Vanadium oxide also undergoes catalyzed monolayer edge recession, forming elongated hexagonal etch pits which are bound by <11{ovr 2}0> (zig-zag) edges. It is shown that there are two different graphite zig-zag steps exhibiting different reactivities which result in the unique shape of the pits. By comparing the monolayer channeling rates with the rates for deep-layer channeling reported in the literature, it is concluded that the relative contribution to the total oxidation rates by monolayer channeling is at least as important as that by deep channeling.

• OSTI ID: 6960654
• Journal Information: Journal of Catalysis; (USA), Vol. 119:1; ISSN 0021-9517
• Country of Publication: United States
• Language: English

Related Subjects

01 COAL, LIGNITE, AND PEAT
COPPER
CATALYTIC EFFECTS
GRAPHITE
OXIDATION
PLATINUM
VANADIUM
VANADIUM OXIDES
CHANNELING
CHEMICAL BONDS
CHEMICAL REACTION KINETICS
LAYERS
MASS TRANSFER
MICROSTRUCTURE
OXYGEN
TRANSMISSION ELECTRON MICROSCOPY
CARBON
CHALCOGENIDES
CHEMICAL REACTIONS
CRYSTAL STRUCTURE
ELECTRON MICROSCOPY
ELEMENTAL MINERALS
ELEMENTS
KINETICS
METALS
MICROSCOPY
MINERALS
NONMETALS
OXIDES
OXYGEN COMPOUNDS
PLATINUM METALS
REACTION KINETICS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
VANADIUM COMPOUNDS
010404* - Coal
Lignite
&amp; Peat- Gasification
010600 - Coal
Lignite
&amp; Peat- Properties &amp; Composition