Measurements of H2O2 in low temperature dimethyl ether oxidation

Huijun Guo, Wenting Sun, Francis M. Haas, Tanvir Farouk, Frederick L. Dryer, Yiguang Ju

Research output: Contribution to journalArticle

54 Scopus citations

Abstract

H2O2 is one of the most important species in dimethyl ether (DME) oxidation, acting not only as a marker for low temperature kinetic activity but also responsible for the "hot ignition" transition. This study reports, for the first time, direct measurements of H2O 2 and CH3OCHO, among other intermediate species concentrations in helium-diluted DME oxidation in an atmospheric pressure flow reactor from 490 to 750 K, using molecular beam electron-ionization mass spectrometry (MBMS). H2O2 measurements were directly calibrated, while a number of other species were quantified by both MBMS and micro gas chromatography to achieve cross-validation of the measurements. Experimental results were compared to two different DME kinetic models with an updated rate coefficient for the H + DME reaction, under both zero-dimensional and two-dimensional physical model assumptions. The results confirm that low and intermediate temperature DME oxidation produces significant amounts of H 2O2. Peroxide, as well as O2, DME, CO, and CH3OCHO profiles are reasonably well predicted, though profile predictions for H2/CO2 and CH2O are poor above and below ∼625 K, respectively. The effect of the collisional efficiencies for the H+O2+M=HO2 + M reaction on DME oxidation was investigated by replacing 20% He with 20% CO2. Observed changes in measured H2O2 concentrations agree well with model predictions. The new experimental characterizations of important intermediate species including H2O2, CH2O and CH 3OCHO, and a path flux analysis of the oxidation pathways of DME support that kinetic parameters for decomposition reactions of HOCH 2OCO and HCOOH directly to CO2 may be responsible for model under-prediction of CO2. The H abstraction reactions for DME and/or CH2O and the unimolecular decomposition of HOCH2O merit further scrutiny towards improving the prediction of H2 formation.

Original languageEnglish (US)
Pages (from-to)573-581
Number of pages9
JournalProceedings of the Combustion Institute
Volume34
Issue number1
DOIs
StatePublished - 2013

All Science Journal Classification (ASJC) codes

  • Chemical Engineering(all)
  • Mechanical Engineering
  • Physical and Theoretical Chemistry

Keywords

  • Dimethyl ether
  • Flow reactor
  • Hydrogen peroxide
  • Low temperature chemistry
  • Molecular Beam Mass Spectrometry

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