A Theoretical and Experimental Study of Catalytic Ignition in the Hydrogen-Oxygen Reaction on Platinum

The catalytic ignition. i.e., the sudden transition from kinetic control to mass transport control, of nonflammable H2/O2 mixtures in N2 at 1 atm, was in this work investigated experimentally and theoretically. Specifically the dependence of the ignition temperature (where the reaction self-accelera...

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Bibliographic Details
Published in:Journal of catalysis 1993-06, Vol.141 (2), p.438-452
Main Authors: Fassihi, M., Zhdanov, V.P., Rinnemo, M., Keck, K.E., Kasemo, B.
Format: Article
Language:English
Subjects:
400201 - Chemical & Physicochemical Properties
Catalysis
CATALYTIC EFFECTS
Catalytic reactions
CHEMICAL REACTION KINETICS
CHEMICAL REACTIONS
Chemistry
COMBUSTION
DESORPTION
ELEMENTS
Exact sciences and technology
General and physical chemistry
HYDROGEN
IGNITION
INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY
KINETICS
MATHEMATICAL MODELS
METALS
NONMETALS
OXIDATION
OXYGEN
PLATINUM
PLATINUM METALS
REACTION KINETICS
SORPTION
Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
THERMOCHEMICAL PROCESSES
TRANSITION ELEMENTS
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Summary:The catalytic ignition. i.e., the sudden transition from kinetic control to mass transport control, of nonflammable H2/O2 mixtures in N2 at 1 atm, was in this work investigated experimentally and theoretically. Specifically the dependence of the ignition temperature (where the reaction self-accelerates due to the released chemical power) on the H2/O2 mixing ratio has been measured and simulated by model calculations. The latter take explicitly into account the surface kinetics of the reaction as well as mass and heat transport. The experimentally observed trend of increasing Tign with increasing H2/O2 ratio can, via the simulations, be attributed to a combination of the hydrogen desorption kinetics and a weaker coverage dependence for H2 sticking than for O2 sticking on the surface. The numerical solution of the full model is compared with an approximate analytical expression for Tign.
ISSN:0021-9517
1090-2694
DOI:10.1006/jcat.1993.1153