Study of individual reactions of the sour compression process for the purification of oxyfuel-derived CO2

Following the feasibility study of sour compression process as a novel purification method of producing NOx-free, SO2-free oxyfuel-derived CO2 using actual fluegas, in this paper, we present the study of the individual reactions taking place in the process in a controlled environment. We have previously showed that an increase of NO/NO2 concentration in the inlet stream is beneficial for SO2 removal as NO2 promotes SO2 oxidation and the further removal as liquid acid. In this study we show that the reaction SO2 + NO2 → SO3 + NO does not take place significantly in the absence of liquid water at a range of conditions relevant to the sour compression process. When liquid water is present, SO2 is oxidised by NO2 regenerating NO with the rate of conversion of SO2 being dependent on the acid concentration in the liquid. The formation of small liquid droplets where very low levels of pH (≪0) can be reached is shown to be of great importance to the SO2 + NO2 conversion process.