New results of H_2S oxidation at high pressures. Experiments and kinetic modeling

摘要

The present study deals with the oxidation of H2S at high pressures. In some local scenarios, combustion is seen as an alternative possibility for the use of sour gas mixtures containing H2S. Therefore, further research is needed in terms of H2S oxidation characteristics and kinetics, which might be useful for existing processes like the Claus process. Experiments have been performed in the present work in a flow reactor under diluted conditions at different manometric pressures (0.6, 10, 20 and 40 bar). The influence of oxygen concentration (lambda = 1 and lambda = 6), temperature (450-1100 K) and gas residence time (371/T(K)-9280/T(K), in seconds) have been studied. At a given pressure, increasing oxygen concentration shifts the onset of H2S conversion to lower temperatures and makes the H2S consumption more abrupt. Gas residence time has an important influence on the H2S oxidation behavior under the experimental conditions studied. A recent kinetic model by the authors has been updated with two new reactions, obtaining a good prediction of H2S oxidation over a wide variety of experimental conditions, both from this work and the literature. The formation of H2O2 species, favored at high pressures, is responsible for the importance of the two new reactions here proposed, improving the model predictions at high pressures. At atmospheric pressure, the reaction pathways obtained using the current mechanism, remain essentially unaltered in comparison with previous studies.