Experimental determination of ethyl methyl carbonate decomposition kinetics to enhance combustion model accuracy

Ethyl methyl carbonate (EMC, C 4 H 8 O 3 ), a solvent in lithium-ion batteries, poses fire risks due to thermal instability, but existing combustion models fail to accurately predict species concentrations and ignition delays. In this study, we conducted EMC pyrolysis experiment in a jet-stirred reactor (JSR) at 620−1010 K and 1.0 bar and quantitively measured the decomposition products by the synchrotron VUV photoionization mass spectrometry and gas chromatography. The pyrolysis at higher temperature of 981–1476 K were examined by employing shock tube (ST) and laser absorption diagnostics. We found EMC mainly decomposing through the retro-ene reaction pathway in JSR and we obtained the rate constants of EMC retro-ene reaction at 710–830 K derived from the mole fraction change of EMC assuming the first order reaction rate. At higher temperature of 981–1476 K in ST, the rate constants are obtained by the measured CO 2 time-histories. The overall best-fit Arrhenius expression of EMC decomposition is found to be: k ( T ) = 2.74×10 13 (s –1 )∙exp[-49.057(kcal∙mol -1 )/ RT ]. By incorporating the determined rate constant into the previous models, the updated kinetic models yield notably improved predictions of mole fraction of EMC and its reaction products, while maintaining good agreement with experimental data on global combustion properties of EMC.