the catalytic reduction of SO2 to elemental sulfur using a stoichiometric amount of H-2 or CO, sulfided Co/Al2O3 or Co! TiO2 catalysts had bifunctional properties; cobalt sulfide generates H2S(with H-2 as reductant) or COS (with CO as reductant) as reaction intermediate and then production of sulfur can be achieved by the reaction between the reaction intermediate (HPS or COS) and SO2 over Al2O3 or TiO2.