Experimental and numerical analysis of the oxidative decomposition of H2S

Recent environmental and economic considerations have made the focus of attention new treatment processes of the residual (tail) gas of Claus plants, based on the oxidative decomposition of H2S to Sulphur and Hydrogen, In this work, the thermal, oxidative decomposition of H2S in an homogeneous phase has been studied by developing a comprehensive chemical kinetic model for the oxidation of H2S in a low oxygen atmosphere, by varying the O2/H2S ratio (0.2–0.35), residence time (150–300 ms), and process temperatures (900–1100 °C). The kinetic model has been developed by combining existing models for the oxidation of H2S, with no tuning of the parameters or kinetic constants and validated in relation to the experimental data. The results show a very good agreement with the experimental values at higher temperatures (1100 °C). At 900 °C, the H2S conversion is well predicted by the model, whereas the H2 yield and SO2 selectivity are consistently higher than the experimental values. A sensitivity analysis for the complex kinetic system has highlighted the importance of the reaction (O2 + S ↔ O + SO) at lower temperatures.