Investigation of nano-CuO/mesoporous SiO₂ materials as hot gas desulphurization sorbents

Gases from gasification processes contain H₂S which is highly harmful for almost all catalyst materials and metal constructions such as in IGCC plants. Metal oxides and/or their admixtures are widely used for the removal of H₂S from gases at high temperatures. These sorbents, however, suffer from several problems which adversely affect their performances. In this study, a new method was explored to prepare sorbents from nano-size (sub-micron) CuO supported on SiO₂ materials. Three sorbents with 38.5 wt.%, 41.5 wt.% and 49.6 wt.% Cu contents were prepared and characterized. Results indicated that, the produced materials are mesoporous composite type materials of nano-size CuO and amorphous SiO₂. The H₂S adsorption characteristics of the prepared sorbents were studied in a laboratory scale fixed-bed reactor through sulfidation-regeneration cycles in the temperature range of 788-838 K at atmospheric pressure. The average sulfur uptake capacities of the sorbents, based on the breakthrough point H₂S concentration of 20 ppm, were determined to be in the range of 2.38-2.91 g S/100 g sorbent after 3 cycles. Although the process at high temperatures appeared to disturb the structure of the sorbents to some extent, the drop in their sulfur adsorption capacities remained limited.