Research on recycling and characterization analysis of the waste SCR catalyst

In the light of a high SO₂ oxidation ratio of the recycled waste SCR catalyst during conventional recycling denitrification, a novel recycling technique, including acid washing, acid leaching under reduction condition and active components loading, was proposed to control the SO₂ oxidation ratio of the recycled catalyst.The experiments were performed to determine the components, denitrification efficiency and SO₂ oxidation ratio of the catalysts obtained in different recycling runs, and the catalysts used were characterized.The results indicate that the denitrification efficiency and SO₂ oxidation ratio of the fresh catalyst, waste catalyst, conventional recycled catalyst and novel recycled catalyst are 99.0% and 0.43%, 77.0% and 0.46%, 94.2% and 0.80%, 99.3% and 0.48%, respectively.Through novel recycling method, both denitrification efficiency and SO₂ oxidation ratio of the recycled catalyst are well recovered.The characterization results suggest that the highly polymerized vanadium species on the surface of the waste catalyst could not be removed by using conventional recycling method, but the novel recycling method is effective for removing these vanadium species and replacing them with highly dispersed vanadium species, resulting in a reduction of SO₂ oxidation ratio of the recycled catalyst.