Catalytic process for reducing nitrogen oxides to nitrogen

Claim 1

A process for reducing nitrogen oxides to nitrogen, which comprises adding ammonia, as substantially the sole reducing agent, to a gaseous mixture containing nitrogen oxides and molecular oxygen, and contacting the resulting gaseous mixture containing nitrogen oxides, molecular oxygen and ammonia, as substantially the sole reducing agent, at a temperature of 150° to 550° C. and at a space velocity of 1,000 to 100,000/hour with a catalyst composition consisting essentially of an intimate mixture of the following components in the following atomic ratios: (A) one atom of titanium (Ti) as component A, (B) 0.01 to 1 atom of at least one metal selected from the following groups B-1 and B-2 wherein group B-1 consists of iron (Fe) and vanadium (V) and group B-2 consists of molybdenum (Mo), tungsten (W), nickel (Ni), cobalt (Co), copper (Cu), chromium (Cr), and uranium (U), with the proviso that when vanadium (V) is selected from group B-1, at least one of molybdenum (Mo) and tungsten (W) from group B-2 is also present in the catalyst composition, and optionally (C) tin (Sn) as component C, and (D) at least one metal as component D selected from the group consisting of silver (Ag), beryllium (Be), magnesium (Mg), zinc (Zn), boron (B), aluminum (Al), yttrium (Y), rare earth elements, silicon (Si), niobium (Nb), antimony (Sb), bismuth (Bi), and manganese (n), wherein when said catalyst composition includes optional component C, it is present in an atomic ratio of component A to component C of 1:003 - 0.2 and said optional component D being present at an atomic ratio of component A to component D of 1:0 - 0.15, said elements of component A, B-2, C and D being contained in said catalyst in the form of oxides, and the iron and vanadium of component B-1 being contained in said catalyst in the form of oxides and/or sulfates.