Mechanism of H₂-O₂ reaction in supercritical water

H₂-O₂ reaction in supercritical water has been widely studied due to its promising application in industry. The global rate of this reaction was found independent of O₂ with equivalence ratio ranging from 0.042 to 4.1 in the literature. Aim of current study is to examine intermediates interaction responsible for properties of the O₂ independence and others. The study involves experiment re-examining the oxygen independence phenomenon and simulation centering on reduced mechanisms derived by quasi-steady-state approximation. The experiment with equivalence ratio ranging from 3.5 to 7.2 produces similar temperature increases, signifying a global reaction rate independent of oxygen. The phenomenon of oxygen independence was then inspected by a three-step reduced mechanism and is attributed to a special role of H + O₂ + M → HO₂ + M. This particular reaction dominating H and O₂ consumption with a fast rate is responsible for the concurrence of independences of its reaction coefficient, H, and O₂ to global reaction rate. Another property that HO₂ quantity indicates reactive intensity was investigated by a two-step reduced mechanism and is credited to a small activation energy of reaction HO₂ + HO₂ → H₂O₂ + O₂ and a thermal system.