So3 reduction catalyst for purifying an exhaust gas, preparation process thereof, and exhaust gas purifying method using the catalyst

Abstract

To provide an SO3 reduction catalyst for purifying an exhaust gas capable of efficiently reducing the amount of SO3 that is present in a combustion exhaust gas and is a starting substance of S-containing substances such as acid ammonium sulfate causing deterioration of performance of the catalyst or corrosion of apparatuses disposed downstream of the catalyst, or capable of controlling the generation of SO3 in the catalyst itself; a preparation process of the catalyst; and an exhaust gas purifying method using the catalyst. In the catalyst for purifying a combustion exhaust gas containing nitrogen oxides, 50 wt. % or greater of the amount of Ru and/or Ir to be supported is adjusted to fall within a depth of 150 μm from the surface layer of a substrate; and the catalyst is prepared by immersing the substrate in a metal colloid solution of Ru and/or Ir to be supported or an aqueous solution containing at least one compound selected from compounds of Ru and/or Ir to be supported.

Dependencies are inferred from the claim text.