Mixed Co–Zn–Al oxides as absorbents for low-temperature gas desulfurisation

Abstract

High-surface-area zinc–cobalt–aluminium oxides have been prepared from coprecipitated hydroxycarbonate precursors. The oxides were tested for their H₂S uptake in a microreactor at 303 K. The precursors all adopted a hydrotalcite-type structure, whilst the oxides were also all single-phase materials. Their structures were either based on that of ZnO or Co₃O₄, which suggested the presence of solid solutions with all the ions dissolved into one phase. A comparison of the H₂S uptake of these materials with that of the Co–Zn oxides suggested that the presence of aluminium ions in the oxide gave rise to an increase in their surface areas, but that the modified compounds did not absorb significantly more H₂S. Indeed, the more Co-rich cobalt–zinc–aluminium oxides absorbed less H₂S than Co–Zn oxides prepared in a similar way.