Low temperature hydrolysis of carbonyl sulfide using Zn-Al hydrotalcite-derived catalysts

A series of Zn-Al hydrotalcite-like compounds (HTLCs) were synthesized by co-precipitation method. The mixed oxides derived from HTLCs were tested for the catalytic hydrolysis of carbonyl sulfide (COS) at relatively low temperatures of 50 degrees C. These catalysts were characterized by X-ray diffraction (XRD) and Thermogravimetry/Derivative Thermogravimetry Analysis (TG-DTA) and the results can help us to understand the effect of preparation conditions. The results showed that the Zn-Al hydrotalcite-like compounds were efficient precursor in preparing active and stable catalysts for hydrolysis of COS. The catalyst performance was strongly related to the synthesis pH and calcination temperature. The optimum condition was pH of 10, and calcination temperature of 400 degrees C. Although water was indispensable for hydrolysis of COS, the excess water would hinder the adsorption of COS. In general, COS was hydrolyzed to H2S, which is depending on the chemistry of the derived oxides. The end-products of hydrolysis were simple substance S and sulfate. The presence of oxygen will accelerate the formation of the final product. (C) 2013 Elsevier B.V. All rights reserved.