Methanol and hydrogen oxidation kinetics in water at supercritical states

Alkam, M.K.; Pai, Vivek; Butler, Paul D.; Pitz, William J.

doi:10.1016/0010-2180(95)00247-2

Cited by 61 publications

(73 citation statements)

References 12 publications

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“…To gain insight into the results of our experiments, we tested an elementary reaction mechanism proposed for the oxidation of methanol in supercritical water. [6,7] The mechanism was assembled from a high-pressure H2-CO mechanism and two atmospheric pressure mechanisms. The rates of key elementary reactions were varied within their uncertainties by the authors to improve agreement with methanol SCWO kinetics experiments performed by .…”

Section: Detailed Summary Of Technical Progress This Periodmentioning

confidence: 99%

See 1 more Smart Citation

Kinetics of Supercritical Water Oxidation

Rice¹,

Tester²,

Brezinsky³

1995

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Public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the data needed, and completing and reviewing this collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this burden to Washington Headquarters Services, Directorate for Information Operations and Reports, 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302, and This project consists of experiments and theoretical modeling designed to improve our understanding of the detailed chemical kinetics of supercritical water oxidation (SCWO) processes. The objective of the three year project is to develop working models that accurately predict the oxidation rates and mechanisms for a variety of key organic species over the range of temperatures and pressures important for industrial applications. Our examination of reaction kinetics in supercritical water undertakes in situ measurements of reactants, intermediates, and products using optical spectroscopic techniques, primarily Raman spectroscopy. Our focus is to measure the primary oxidation steps that occur in the oxidation of methanol, phenol, methylene chloride, and some simple organic compounds containing nitro groups with a special emphasis on identifying reaction steps that involve hydroxyl radical and hydrogen peroxide. SUBJECT TERMSsupercritical water oxidation (SCWO), optical spectroscopic techniques, Raman spectroscopy, SERDP Project description: This project consists of experiments and theoretical modeling designed to improv* our understanding of the detailed chemical kinetics of supercritical water oxidation (SCWO) processes. The objective of the three year project is to develop working models that accurately predict the oxidation rates and mechanisms for a variety of key organic species over the range of temperatures and pressures important for industrial applications. Our examination of reaction kinetics in supercritical water undertakes in situ measurements of reactants, intermediates, and products using optical spectroscopic techniques, primarily Raman spectroscopy. Our focus is to measure the primary oxidation steps that occur in the oxidation of methanol, phenol, methylene chloride, and some simple organic compounds containing nitro groups with a special emphasis on identifying reaction steps that involve hydroxyl radical and hydrogen peroxide.The work conducted here continues the experimental approach from our previous SERDP-funded project by extending measurements on key oxidant species and expanding the variety of experimental methods, primarily optical in nature, that can be used to examine reactions at SCWO conditions. Direct support will be sent to the project collaborators at MIT and Princeton who will contribute to the model development for the halogenated systems and phenol. In general, these researchers will exami...

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Section: Detailed Summary Of Technical Progress This Periodmentioning

confidence: 99%

“…To understand what causes this downturn, we identified two important reactions from a set of rate-controlling reactions highlighted in earlier studies. [6,10] The first reaction is the unimolecular decomposition of H2O2, which is an important chainbranching step:…”

Section: Detailed Summary Of Technical Progress This Periodmentioning

confidence: 99%

Kinetics of Supercritical Water Oxidation

Rice¹,

Tester²,

Brezinsky³

1995

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“…Previous modeling efforts yielded kinetic mechanisms describing the oxidation of simple compounds such as hydrogen [2][3][4][5][6][7], carbon monoxide [3,5,6], methane [5,6,8,9], methanol [6,7,[10][11][12][13][14], and phenol [15]. The model predictions have been compared, with varying degrees of success, to experimentally measured species concentration profiles.…”

Section: Introductionmentioning

confidence: 99%

Analysis of an elementary reaction mechanism for benzene oxidation in supercritical water

DiNaro

Howard

Green

et al. 2000

Proceedings of the Combustion Institute

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A benzene supercritical water oxidation (SCWO) mechanism, based on published low-pressure benzene combustion mechanisms and submechanisms describing the oxidation of key intermediates, was developed and analyzed to determine the controlling reactions under SCWO conditions of 750-860 K, 139-278 bar, and equivalence ratios from 0.5 to 2.5. To adapt the combustion mechanisms to the lower temperature (Ͻ975 K) and higher pressure (Ͼ220 bar) conditions, new reaction pathways were added, and quantum Rice-Ramsperger-Kassel theory was used to calculate the rate coefficients and, hence, product selectivities for pressure-dependent reactions. The most important difference between the benzene oxidation mechanism for supercritical water conditions and those for combustion conditions is reactions in supercritical water involving C 6 H 5 OO predicted to be formed by C 6 H 5 reacting with O 2 . Through the adjustment of the rate coefficients of two thermal decomposition pathways of C 6 H 5 OO, whose values are unknown, the model accurately predicts the measured benzene and phenol concentration profiles at 813 K, 246 bar, stoichiometric oxygen, and 3-7 s residence time and reproduces the finding that the carbon dioxide concentration exceeds that of carbon monoxide at all reaction conditions and levels of benzene conversion. Comparison of the model predictions to benzene SCWO data measured at several different conditions reveals that the model qualitatively explains the trends of the data and gives good quantitative agreement without further adjustment of rate coefficients.

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“…More recently, Holgate has reformulated Helling's carbon monoxide and hydrogen mechanism and demonstrated success in predicting experimental data (Holgate and Tester, 1994a;Holgate and Tester, 1994b). This work has been recently incorporated into a new mechanism for methane and methanol oxidation developed by Pitz and collaborators (Alkam, et al , 1995).…”

Section: Kinetics Modelsmentioning

confidence: 99%

“…Pitz made minor changes when assembling these sub-mechanisms (Alkam, et al, 1995). In his kinetics study, Holgate chose a low value of heat of formation for HO2 (within the range of published values) in order to best match his experimental data (Holgate, 1993).…”

Section: Methane Modelmentioning

confidence: 99%

Methane and methanol oxidation in supercritical water: Chemical kinetics and hydrothermal flame studies

Steeper¹

1996

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Methanol and hydrogen oxidation kinetics in water at supercritical states

Cited by 61 publications

References 12 publications

Kinetics of Supercritical Water Oxidation

Kinetics of Supercritical Water Oxidation

Analysis of an elementary reaction mechanism for benzene oxidation in supercritical water

Methane and methanol oxidation in supercritical water: Chemical kinetics and hydrothermal flame studies

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