Simultaneous removal of H 2S and COS using activated carbons and their supported catalysts

Abstract

Adsorption and catalytic decomposition of H 2S and COS were investigated over active carbons using a flow reactor with fixed bed in the temperature range from 300 to 450 °C. Active carbons removed very effectively COS at a relatively high temperature of 400 °C, some portion being decomposed to CO over active carbons. Although H 2S was also removed by active carbons at 400 °C, the removal capacity of H 2S was much smaller than that of COS and H 2S was hardly decomposed over active carbons. The impregnation of Fe on the active carbon enhanced very much the removal of both COS and H 2S; however, their decomposition behaviors were much different. It is found that the decomposition of H 2S was enhanced by Fe-supported activated carbon derived from a brown coal, while no decomposition of COS took place over the same Fe-supported active carbon. These results indicate that H 2S may be dominantly removed through the reaction with metal to produce metal sulfide, while COS may be preferably adsorbed as COS itself in the pore of active carbon and then may react with carbon surface to be decomposed to CO. Such contrast adsorption and decomposition behaviors of COS and H 2S are discussed based on their chemical reactivity over active carbon-supported catalyst.