US Patent 7160839 Catalyst for purifying nitrogen oxides

A catalyst for purifying NOx is provided which efficiently decomposes and purify the NOx in an exhaust gas in an oxygen-excess atmosphere, excels in resistance to heat and in durability in a high temperature range under a high-temperature oxidizing atmosphere and in the presence of moisture and SOx, and manifests the catalytic activity over a wide range of temperature. It is a catalyst for purifying nitrogen oxides formed by coating (A) a catalytically active component comprising (A-a) iridium and (A-b) at least one element selected from the group consisting of the elements of Group IIIA and Group IVA in the Periodic Table of the Elements with (B) a refractory inorganic compound.