Regenerative copper–alumina H2S sorbent for hot gas cleaning through chemical swing adsorption

This article focuses on desulfurization, of hot syngas from gasification of solid fossil fuels, in the temperature range of 300–500 °C via copper-based adsorbents. The slip of H2S above the developed adsorbent materials for hot cleaning of syngas has been studied together with the regeneration mechanism, using thermodynamic analysis, thermogravimetry, and packed-bed reactor experiments, in order to establish an efficient approach to regenerate the adsorbent. Supported copper on gamma alumina used as H2S adsorbent in this study shows H2S slips lower than 5 ppm in the temperature range of 350–550 °C. The copper-based sorbent shows around 2 wt % sulfur sorption capacity in the temperature range of study. The kinetic evaluation confirms that the sorption kinetics for this sorbent yield sufficient performance for real process operation even at such low temperatures. Aiming at isothermal operation, the chemical swing process is identified as an efficient way to regenerate the adsorbent. In this regeneration process, the sulfide phase is stabilized to sulfate in air followed by a fast regeneration stage in the presence of a small stream of hydrogen.