Oxidation of Hydrogen Sulfide in Shock Waves. I. Absorption Studies of OH and SO2 in H2S–O2–Ar Mixtures

The oxidation of hydrogen sulfide in shock waves has been studied over the temperature range 1350°—2450°K by following the characteristic absorption of OH and SO₂. Two different regions are apparent: below 1560°K the OH and SO₂ appear together, after an induction period, while above 1700°K the SO₂ appears before the OH. The oxidation at low temperatures is interpreted in terms of a branching‐chain mechanism involving the reactions: $$\begin{array}{c}\mathrm{SH}+{\mathrm{O}}_2\to \mathrm{SO}+\mathrm{OH},\\ \mathrm{OH}+{\mathrm{H}}_2\mathrm{S}\to {\mathrm{H}}_2\mathrm{O}+\mathrm{SH},\\ \mathrm{SO}+{\mathrm{O}}_2\to {\mathrm{SO}}_2+\mathrm{O},\\ \mathrm{O}+{\mathrm{H}}_2\mathrm{S}\to \mathrm{OH}+\mathrm{SH.}\end{array}$$ At higher temperatures, participation of the reaction $$\mathrm{O}+{\mathrm{H}}_2\mathrm{S}\to \mathrm{SO}+{\mathrm{H}}_2$$ provides an additional route for the formation of SO₂ and hence leads to a reduced induction time for its appearance.