| Abstract
| - Our earlier study showed that when H2S and concentrated sulfuric acid react, H2S is first oxidizedby molecular H2SO4 and then consecutively by SO2, a product of the first oxidation step. Therate of the first reaction was measured using initial rate analysis at temperatures and acidconcentrations under which conditions the second reaction may be neglected. In this study, thekinetics of the second reaction, i.e., the reaction between hydrogen sulfide and sulfur dioxide insulfuric acid solutions, was studied at 20−50 °C and 30−60 wt % of acid concentration, underwhich conditions the rate of the first reaction is negligible. The second reaction follows first-order kinetics with respect to the partial pressure of H2S in the gas phase and also to theconcentration of SO2 in the solution. Changes in acid concentration do not affect the rate constant.The activation energy and the preexponential factor of the reaction at all acid concentrationsstudied are 59.02 kJ mol-1 and 11 900 L s-1 m-2 Pa-1, respectively. Further experiments showthat the measured kinetic results also apply to the second reaction in sulfuric acid atconcentrations exceeding 60 wt %.
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