Insights into pyrolysis and oxidation of 1,3-dioxane: Experimental and kinetic modeling study

1,3-Dioxane (DIOX) is a significant synthetic biofuel that contributes to achieving carbon peak and carbon neutrality goals. However, there is a relative scarcity of research on the pyrolysis and oxidation reaction kinetics of 1,3-dioxane. To gain deeper insights into the kinetic mechanisms of 1,3-dioxane pyrolysis and oxidation, the experimental and simulated analyses of 1,3-dioxane were carried out at intermediate temperatures in this work. The concentration curves of small molecule products and major intermediates were measured using GC and GC-MS. A new detailed kinetic mechanism was developed based on typical reaction classes and rate coefficients, and validated with the experimental data. In comparison to previous models, the new mechanism incorporates carbene reactions, which are significant for the initial decomposition pathways of 1,3-dioxane. The reaction network was further refined with the detection of key intermediates C₃H₅OCHO (CH₃CH=CH-O-CH=O) and C₂H₃CHO (CH₂=CH-CH=O) in this work. Model analysis shows that the fuel radical dehydrogenation to olefin plays a more dominant role at $\text{ϕ =\hspace{0.17em}}2.0$ than $\text{ϕ =\hspace{0.17em}}0.5$, while the isomerization reaction of RȮ₂ to Q̇OOH is much weaker under fuel-rich condition. The reaction network analysis suggests that 4,5-dihydro-1,3-dioxin (DIOXENE) is the core precursor for C₃H₅OCHO and C₂H₃CHO, which are also precursors for some small molecule products. Furthermore, the kinetic model was validated against ignition delay times, and the simulated results demonstrate that the model accurately reflects the actual combustion characteristics of the fuel above 750 K. In general, the new detailed model in this work shows good prediction ability for the concentration trends of major products and combustion properties.