Exploring the Oxidative Decompositions of Methyl Esters: Methyl Butanoate and Methyl Pentanoate as Model Compounds for Biodiesel

Published

October 7, 2008

Author(s)

Carrigan J. Hayes, Donald R. Burgess Jr.

Abstract

Methyl esters are commonly used as surrogates for complex biofuel chemistry; this utility necessitates development of combustion mechanisms for these species. A pathway accounting for early CO2 production in the combustion of methyl esters, using methyl butanoate as a model biofuel, has recently been proposed in the literature. We quantified this pathway using composite (G3B3) calculations and identified areas for potential side reactions, in both methyl butanoate and metyl pentanoate. Alternative isomerizations were also examined and suggest that side reactions may play an increasingly larger role in the chemistry of long-chain methyl esters, compared to methyl butanoate. As their complexities increase, combustion mechanisms rely to ever greater extents on the inclusion of parameters derived from composite and density functional theory (DFT) calculations. A methodological survey was undertaken. G3MP2B3 calculations matched quantitatively and qualitatively well with the benchmark G3B3 data, while density functional theory (DFT) approaches failed to achieve the accuracy or precision desirable for inclusion of parameters derived via this method in combustion mechanisms. Energies generated via G3MP2B3 calculations were used to explore kinetic parameters for reactions implicated in CO2 combustion and competing pathways; these parameters were compared to extant mechanistic data.

Citation

Proceedings of the Combustion Institute

Volume

32

Pub Type

Journals

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DOI Link

Keywords

peroxy radical, combustion, composite, DFT, methyl esters, biodiesel, mechanism

Citation

Hayes, C. and Burgess, D. (2008), Exploring the Oxidative Decompositions of Methyl Esters: Methyl Butanoate and Methyl Pentanoate as Model Compounds for Biodiesel, Proceedings of the Combustion Institute, [online], https://doi.org/10.1016/j.proci.2008.05.075 (Accessed April 25, 2024)