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 k5b=(2–1+2)× 10–11 and k6=(2.5 ± 1)× 10–11 cm3 molecule–1 s–1 at 306 K, 1 atmosphere pressure.