Kinetics measurements of methane oxidation in supercritical water

Richard R. Steeper, Steven F. Rice, Ian M. Kennedy, Jason D. Aiken

Research output: Contribution to journalArticlepeer-review

38 Scopus citations


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, highpressure elementary reaction mechanism reproduces this downturn in rates and provides insight into the reasons for this behavior.

Original languageEnglish (US)
Pages (from-to)184-189
Number of pages6
JournalJournal of Physical Chemistry
Issue number1
StatePublished - Jan 4 1996

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Engineering(all)


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