Desulfurization of air at high and low H 2S concentrations

Abstract

Several commercially available coconut-based activated carbons were tested as adsorbents of hydrogen sulfide (H 2S) at high and low H 2S concentrations. These carbons were compared to an experimental coconut-based carbon modified by impregnation with strongly basic compounds and an oxidant. The breakthrough curves for H 2S at 3000 ppm and 10 ppm were measured at room temperature. The effects of humidity and water content on H 2S removal were investigated. The carbon samples were characterized before and after H 2S adsorption using XRF, sorption of nitrogen, thermal analysis in combination with mass spectrometry (TGA–MS) and thermal desorption–gas chromatography–mass spectrometry (TD–GC–MS), along with pH measurements. These methods were used to track the activated carbon surface chemical changes upon H 2S adsorption/reactive adsorption. The amount of H 2S adsorbed on all activated carbons was found to be dependent on the amount of surface basic groups. TGA–MS and TD–GC–MS analysis revealed H 2S is adsorbed via reactive adsorption mechanisms. Metal sulfates, elemental sulfur, carbon sulfide, oxides of sulfur and dihydrogen disulfide are the products of surface reactions.