Significance of micropores for removal of hydrogen sulfide from oxygen-free gas streams by activated carbon

Abstract

Abstract Activated carbon materials are widely used adsorbents for removal of hydrogen sulfide (H2S) during purification of gas streams. Five commercially available wood-, coal-, and coconut shell-based activated carbons, prepared by phosphoric acid activation and steam activation, were chosen as adsorbents. The removal of H2S by these materials was studied by plotting breakthrough curves to determine the effect of pore structure on H2S adsorption from an oxygen-free gas stream. Conventional catalyst-loaded activated carbons were not as effective under these conditions compared with H2S removal from an oxygen-containing stream. The results showed that adsorption of H2S by activated carbon under oxygen-free conditions was dependent on the microporous structure, particularly micropores with size of 1 nm. The H2S breakthrough capacity of CS-3 was 0.026 g/cm3 under oxygen-free conditions. Compared with conventional KOH- and CuO-loaded activated carbons, the steam activated materials with highly developed micropore structures were better adsorbents for H2S removal because of their high adsorption capacities and reduced fire risk. Moreover, it was found that pre-adsorption or co-adsorption of carbon tetrachloride led to poisoning of the activated carbon for H2S adsorption.