Supported transition-metal oxide catalysts for reduction of sulfur dioxide with hydrogen to elemental sulfur

This work is for the purpose to find a high performance catalyst for the catalytic reduction of SO, with H, as a reducing agent. NiO/gamma-Al2O3 catalyst was found to be the most active catalyst among the seven gamma-Al2O3 -supported metal-oxide catalysts tested. With NiO as the active species, of the supports tested, gamma-Al2O3 was the most suitable one and the optimal Ni content was 16 wt%. Using this NiO/gamma-Al2O3 catalyst, we found that the optimal feed ratio of H-2/SO2 is 2:1 and the catalyst presulfided with H-2 + H2S exhibits a higher performance than that pretreated with H-2 or He. XRD patterns reveal that the nickel oxide experienced a transformation to Ni3S2 and NiS, and then to NiS2, the most active nickel sulfide, during the reaction process. The reason for the highest catalyst activity of 16 wt% Ni was attributed to the largest amount of NiS2. Water vapor in the feed gas reactant caused inhibition of catalyst activity, whereas H,S promoted the reduction of SO2. These phenomena were rationalized with the aid of Claus reaction. (C) 2004 Elsevier Ltd. All rights reserved.