Kinetics Measurements of Methane Oxidation in Supercritical Water

Results and analysis of the oxidation of methane in supercritical water by oxygen over a pressure range from 35 to 270 bar and a temperature range from 390 to 440 °C are presented. Raman spectroscopy is used as an in situ diagnostic to monitor the concentration of methane, oxygen, carbon monoxide, a...

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Bibliographic Details
Published in:Journal of physical chemistry (1952) 1996-01, Vol.100 (1), p.184-189
Main Authors: Steeper, Richard R, Rice, Steven F, Kennedy, Ian M, Aiken, Jason D
Format: Article
Language:English
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Summary:Results and analysis of the oxidation of methane in supercritical water by oxygen over a pressure range from 35 to 270 bar and a temperature range from 390 to 440 °C are presented. Raman spectroscopy is used as an in situ diagnostic to monitor the concentration of methane, oxygen, carbon monoxide, and carbon dioxide in a constant volume reactor. Reaction orders with respect to methane and oxygen at 270 bar and at methane concentrations near 0.1 mol/L are close to two and zero, respectively. A nonmonotonic dependence of reaction rates on water concentration is observed. With temperature and initial concentrations held constant, methane consumption rates first increase with water concentration but reach a maximum near 5 mol/L. Further increases in water concentration lead to a sharp decrease in the rate of methane consumption. An existing, high-pressure elementary reaction mechanism reproduces this downturn in rates and provides insight into the reasons for this behavior.
ISSN:0022-3654
1541-5740
DOI:10.1021/jp951925h