Experimental study of fuel decomposition and hydrocarbon growth processes for practical fuel components in nonpremixed flames: MTBE and related alkyl ethers

Abstract

AbstractFuel decomposition and hydrocarbon growth processes of methyl tert‐butyl ether (MTBE) and related alkyl ethers have been studied experimentally in soot‐producing nonpremixed flames. Temperature, C1–C12 hydrocarbons, and major species were measured in coflowing methane/air flames whose fuel was separately doped with 5000 ppm of MTBE, n‐butyl methyl ether (NBME), sec‐butyl methyl ether (SBME), ethyl tert‐butyl ether (ETBE), and tert‐amyl methyl ether (TAME; =1,1‐dimethylpropyl methyl ether). The consumption rates of the dopants, several simple kinetic calculations, and the dependence of the observed products on fuel composition indicate that the dominant decomposition process was unimolecular dissociation, not H‐atom abstraction. The dominant dissociations were four‐center elimination of alcohols for the doubly branched ethers (MTBE, ETBE, and TAME) and CO fission for the linear ether (NBME), while four‐center elimination and CO fission were comparably important for the singly branched ether (SBME). These dissociations produced alkenes which further reacted to produce alkadienes/alkynes, alkenynes, acetylenic compounds, and aromatics. The dependence of the maximum benzene mole fractions on fuel composition was consistent with benzene formation through reactions of highly‐unsaturated C3 and/or C4 hydrocarbons (C3H3, n‐C4H3, C4H4, n‐C4H5, etc.). © 2004 Wiley Periodicals, Inc. Int J Chem Kinet 36: 345–358, 2004