Investigation of Di-tert-butyl peroxide combustion: time-resolved speciation, laminar flame speed, and model evaluation

Di‑tert‑butyl peroxide (DTBP), a cetane improver, consists of two tert‑butoxy groups bonded by a weak peroxide bond. A thorough understanding of the combustion mechanisms of DTBP is essential for its effective use as a fuel additive. This study systematically investigates the pyrolysis and oxidation characteristics of DTBP through a combination of experimental measurements and kinetic modeling. Laser absorption spectroscopy was employed to achieve time-resolved quantification of key species, including CO, CO₂, OH, and H₂O, during DTBP pyrolysis and oxidation under conditions spanning 1265 - 2000 K and 1.1 - 1.6 bar. The laminar flame speed of DTBP was measured for the first time over a range of equivalence ratios (0.65 - 1.4), initial pressures (0.5 - 2 bar), and a fixed initial temperature of 373 ± 3 K. These experimental results provide essential constraints for optimizing and validating the DTBP kinetic model. The proposed model significantly improved the accuracy of predictions for ignition delay times and laminar flame speeds. Furthermore, the model demonstrated excellent performance in capturing the second-stage ignition delay, overcoming the limitations of previous models. However, the current model still exhibits noticeable deviations in predictions below 1300 K, particularly in the formation dynamics of key species such as CO. To improve the model's accuracy under these conditions, further high-fidelity quantum chemical calculations are needed to refine the rate constants of additional unimolecular decomposition and hydrogen abstraction pathways of DTBP. Overall, by incorporating the latest sub-mechanism of acetone oxidation and updated rate constants for DTBP decomposition reactions, this study provides valuable experimental data and kinetic insights to advance combustion kinetic models for oxygenated fuels and support the development of high-efficiency combustion technologies.