Kinetics and Mechanism of Oxidation of Hydrogen Sulfide by Concentrated Sulfuric Acid

Our previous studies have shown that two reactions are significant when H2S is contacted with concentrated sulfuric acid: At temperatures from 20 to 60 °C and acid concentrations from 88 to 100 wt %, the rate of the first reaction was measured in terms of the initial rate of pressure drop when H2S and concentrated sulfuric acid were brought together in a volume-constant batch reactor. It is indicated that the reaction is first order with respect to H2S. The global rate constant includes the effects of temperature and acid concentration. The effect of temperature was correlated using the Arrhenius equation. The activation energy and the natural logarithm of the preexponential factor are linearly related to the acid concentration. An illustration of molecular collision at the gas−liquid interface was shown to explain the reaction mechanism. This study also provides a kind of quantitative measurement for the oxidizing ability of concentrated sulfuric acid.