Isomer-Specific Influences on the Composition of Reaction Intermediates in Dimethyl Ether/Propene and Ethanol/Propene Flame

Journal Article · Wed May 28 00:00:00 EDT 2008 · Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory

DOI:https://doi.org/10.1021/jp8011188· OSTI ID:1060555

Wang, Juan ^[1]; Struckmeier, Ulf ^[2]; Yang, Bin ^[2]; Cool, Terrill A. ^[2]; Osswald, Patrick ^[2]; Kohse-Höinghaus, Katharina ^[2]; Kasper, Tina ^[2]; Hansen, Nils ^[2]; Westmoreland, Phillip R. ^[2]

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1. School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, Department of Chemistry, Bielefeld University, Universitätsstrasse 25, D-33615 Bielefeld, Germany, Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, and Department of Chemical Engineering, University of Massachusetts Amherst, Amherst, Massachusetts 01003; Combustion Research Facility, Sandia National Laboratories, Livermore, CA 94551
2. School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, Department of Chemistry, Bielefeld University, Universitätsstrasse 25, D-33615 Bielefeld, Germany, Combustion Research Facility, Sandia National Laboratories, Livermore, California 94551, and Department of Chemical Engineering, University of Massachusetts Amherst, Amherst, Massachusetts 01003

This work provides experimental evidence on how the molecular compositions of fuel-rich low-pressure premixed flames are influenced as the oxygenates dimethyl ether (DME) or ethanol are incrementally blended into the propene fuel. Ten different flames with a carbon-to-oxygen ratio of 0.5, ranging from 100% propene (φ = 1.5) to 100% oxygenated fuel (φ = 2.0), are analyzed with flame-sampling molecular-beam mass spectrometry employing electron- or photoionization. Absolute mole fraction profiles for flame species with masses ranging from m/z = 2(H₂) to m/z = 80 (C₆H₈) are analyzed with particular emphasis on the formation of harmful emissions. Fuel-specific destruction pathways, likely to be initiated by hydrogen abstraction, appear to lead to benzene from propene combustion and to formaldehyde and acetaldehyde through DME and ethanol combustion, respectively. While the concentration of acetaldehyde increases 10-fold as propene is substituted by ethanol, it decreases as propene is replaced with DME. In contrast, the formaldehyde concentration rises only slightly with ethanol replacement but increases markedly with addition of DME. Allyl and propargyl radicals, the dominant precursors for benzene formation, are likely to be produced directly from propene decomposition or via allene and propyne. Benzene formation through propargyl radicals formed via unsaturated C₂ intermediates in the decomposition of DME and ethanol is negligibly small. As a consequence, DME and ethanol addition lead to similar reductions of the benzene concentration.

• Research Organization: Cornell Univ., Ithaca, NY (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: FG02-01ER15180
• OSTI ID: 1060555
• Report Number(s): DOE-ER15180-17
• Journal Information: Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory, Journal Name: Journal of Physical Chemistry. A, Molecules, Spectroscopy, Kinetics, Environment, and General Theory Journal Issue: 39 Vol. 112; ISSN 1089-5639
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English

Related Subjects

10 SYNTHETIC FUELS
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
CHEMICAL KINETIC-MODEL
COMBUSTION CHEMISTRY
ELEMENTARY REACTIONS
ETHANOL OXIDATION
ETHYLENE-AIR FLAMES
FUEL-RICH PROPENE
HYDROCARBON GROWTH-PROCESSES
OXYGENATED HYDROCARBONS
PHOTOIONIZATION MASS-SPECTROMETRY
REACTION-MECHANISM