Kinetics of the chlorine-photosensitized oxidation of hydrogen at 1 atmosphere pressure, 306 K

Abstract

The chlorine-photosensitized oxidation of hydrogen has been studied at 1 atmosphere total pressure and 306 K in a stopped-flow system. Hydrogen peroxide is the main oxidation product and its formation kinetics at high hydrogen concentrations are consistent with the following simple reaction scheme involving Cl, H and HO₂: Cl₂+hv→Cl + Cl, Cl + H₂→HCl + H, H + O₂+ M→HO₂+ M, HO₂+ HO₂→H₂O₂+ O₂. At lower hydrogen concentrations, a marked inhibition in the H₂O₂ production and Cl₂ decay rates was observed, due to the reactions (5b) and (6), Cl + ClOO→Cl₂+ O₂, Cl + HO₂→HCl + O₂. (6) Computer analysis of the experimental data gave k_5b=(2^–1₊₂)× 10^–11 and k₆=(2.5 ± 1)× 10^–11 cm³ molecule^–1 s^–1 at 306 K, 1 atmosphere pressure.