Experimental and kinetic modeling study of ethyl acetate pyrolysis and oxidation in a shock tube

Ethyl acetate (EA) is not only a promising biofuel that offers new pathways for sustainable energy applications, but also widely used as an organic solvent in explosives. Given its flammability and potential explosion hazards, understanding its combustion characteristics is crucial. This study systematically investigated EA combustion using a shock tube combined with a laser absorption diagnostic system. Ignition delay times (IDTs) were measured at 1160–1446 K, atmospheric pressure, and equivalence ratios (Φ) from 0.25–2.0. The results indicate that fuel-lean conditions yield nearly identical IDTs due to sufficient oxygen promoting rapid oxidation, whereas stoichiometric and fuel-rich mixtures show reduced reactivity. The diagnostic system simultaneously tracked CO and CH₄ time histories during EA pyrolysis at 1446–1815 K for 0.6% and 1.0% concentrations, showing the temperature-dependent temporal evolution of these key products. A detailed kinetic model was constructed based on previous studies by updating the reaction rate constants for five key reactions involving CH₃COOH, CH₂CO, and C₂H₄. The current model was validated against the extensive experimental data from this work and the literature. Rate of production and sensitivity analyses identified that EA rapidly decomposes via six-membered elimination to CH₃COOH and C₂H₄, and subsequent CH₃COOH decomposition significantly influences the temporal profiles of key products. At fixed dilution, as Φ increases and the availability of O₂ becomes scarcer, H consumption shifts toward the pathway of C₂H₄ + H <=> C₂H₃ + H₂, further suppressing the chain-branching reaction of O₂ + H <=> OH+O and lengthening the IDT. This investigation provides a foundation for optimizing kinetic models of more complex ester fuels and offers a basis for improved safety assessment. Novelty and significance statement: This study provides comprehensive ignition delay time (IDT) data for ethyl acetate (EA) oxidation over a wide range of equivalence ratios, together with simultaneous high-resolution laser diagnostics of CO and CH₄ during EA pyrolysis. Notably, this study provides the first direct online detection of CH₄ under pyrolytic conditions, combined with CO measurements, which serves as a critical benchmark for evaluating the CH₃COOH sub-mechanisms and improving the accuracy of EA kinetic models. A detailed kinetic model for EA combustion was developed by updating five key reaction rate constants based on published literature and was extensively validated against IDTs, major species profiles, and laminar flame speeds. Overall, this study advances the understanding of EA combustion chemistry and establishes a robust framework for modeling oxygenated esters, providing a foundation for developing pathway inhibitors and for post-accident analysis of explosion mechanisms, thereby supporting safety evaluation and risk assessment.