On the competition between hydrogen abstraction versus C-O bond fission in initiating dimethyl ether combustion

Journal Article · Thu Jul 01 04:00:00 EDT 1999 · Combustion and Flame

DOI:https://doi.org/10.1016/S0010-2180(99)00009-7· OSTI ID:355729

Francisco, J ^[1]

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1. Purdue Univ., West Lafayette, IN (United States). Dept. of Chemistry

There has been a growing interest in the potential use of dimethyl ether (DME) as a diesel fuel in compression ignition engines. There are two initiation steps involved in the combustion of DME, one involving C-O bond fission and the other involving hydrogen abstraction by molecular oxygen. The kinetics and thermodynamics of C-O bond fission were explored computationally in a previous paper. The present paper addresses the competing process--hydrogen abstraction by molecular oxygen. Ab initio molecular orbital calculations are used to study the structures and energetics of the reactants, products, and the transition state for the CH{sub 3}OCH{sub 3} + O{sub 2} reaction. The calculations predict a barrier for hydrogen abstraction from CH{sub 3}OCH{sub 3} by O{sub 2} of 47.4 kcal/mol. This is lower than the barrier height for C-O bond fission previously calculated to be 81.1 kcal/mol. The results support values used in current models for the combustion of DME. Moreover, an examination of rates for C-O bond fission versus hydrogen abstraction by O{sub 2} suggests that the bimolecular process is the dominant pathway.

• OSTI ID: 355729
• Journal Information: Combustion and Flame, Journal Name: Combustion and Flame Journal Issue: 1-2 Vol. 118; ISSN CBFMAO; ISSN 0010-2180
• Country of Publication: United States
• Language: English

Related Subjects

10 SYNTHETIC FUELS
33 ADVANCED PROPULSION SYSTEMS
CHEMICAL BONDS
CLEAVAGE
COMBUSTION KINETICS
DIESEL ENGINES
ETHERS
FUEL SUBSTITUTION
HYDROGEN TRANSFER
THERMODYNAMICS