Well-dispersed Cu[sbnd]Fe doping nanoparticles with mixed valence in carbon aerogel as effective adsorbent for H2S removal at low temperature

Abstract

In order to overcome the deficiencies of low adsorption capacity and poor tolerance to high space velocities of commercial adsorbents for H2S removal, core-shell structured Cu-Fe/carbon aerogels (CA) with mixed valence of Cu and Fe were synthesized. The doping of Cu decreased the average size of Fe nanoparticles and enhanced the dispersion of nanoparticles. In addition, parts of oxides were reduced to Cu0 and Fe0 by carbon shell during carbonization process, resulting in the coexistence of mixed valence CuFe doped nanoparticles in CA. The existence of Cu0 and Fe0 nanoparticles is the key contributor for excellent tolerance to high space velocities, where the H2S could be easily adsorbed and dissociated to form reactive intermediate such as HS− and S2−. The well dispersed CuFe doping oxides are the active sites for H2S capture, benefiting for the high H2S adsorption capacity. The adsorbed water can be dissociated to hydroxyl groups over iron oxide, which is more conducive to the removal of H2S. The H2S (200 ppm H2S in CH4) adsorption capacity of optimized adsorbent was 221.1 mg∙g−1 at 100% relative humidity. This study provided a new insight into the synthesis of Cu-based and Fe-based adsorbents for the removal of H2S.