An experimental and theoretical kinetic modeling study of the thermal decomposition of methyl-2-methyl butanoate behind shock waves

In order to investigate the combustion chemistry of a branched ester namely Methyl-2-methylbutanoate (M2MB), thermal decomposition of M2MB diluted in Argon was carried out behind reflected shock waves in the temperature range 959-1392 K using a single pulse shock tube (SPST). The post shock mixtures were analyzed quantitatively as well as qualitatively using gas chromatography (GC) and gas chromatography coupled with mass spectrometry (GC-MS). Methane (CH4), Ethane (C2H6), Ethylene (C2H4), Methanol (CH3OH), Propene (C3H6) and Methyl acrylate (C4H6O2) were the major products observed during thermal decomposition. The various oxygenated compounds were found as minor products. The first order rate constant observed for the decomposition of M2MB is k(expt)(959-1392 K) = (2.13 +/- 0.457) x 10(9) exp [(19200 +/- 561)/T] s(-1) The temperature dependent kinetics of the C-C and C-O homolytic bond cleavages as well as of the H-migration for the unimolecular decomposition reactions were calculated using RRKM/ME over the temperature range of 959-1392 K. A reaction scheme involving 42 species and 61 elementary reactions, was proposed to simulate the reactant and product concentration over the studied temperature range. A comparison study of decomposition kinetics of branched chain ester and long chain ester is discussed in this work. The concentration profiles for reactant and all the products observed from simulations and experimental results were observed to be in very good agreement. (c) 2023 The Combustion Institute. Published by Elsevier Inc. All rights reserved.

Automated summary

Thermal decomposition of Methyl-2-methylbutanoate (M2MB) was investigated in a single pulse shock tube (SPST) using reflected shock waves in the temperature range of 959-1392 K. Gas chromatography (GC) and gas chromatography coupled with mass spectrometry (GC-MS) were used to analyze the post shock mixtures quantitatively and qualitatively. The major products observed during the thermal decomposition included Methane, Ethane, Ethylene, Methanol, Propene, and Methyl acrylate. Minor products of oxygenated compounds were also found. The kinetics of the decomposition reactions were calculated using RRKM/ME and a reaction scheme involving 42 species and 61 elementary reactions was proposed.