Selective catalytic reduction catalyst and a process for preparing a selective catalytic reduction catalyst

A process for preparing a catalyst for a selective catalytic reduction of nitrogen oxide comprising a coating comprising iron and a zeolitic material comprising copper, the process comprising:

• (i) preparing a first aqueous mixture comprising water and a zeolitic material comprising copper;
• (ii) disposing the first aqueous mixture obtained according to (i) to a substrate, wherein the substrate comprises an inlet end, an outlet end, a substrate axial length extending from the inlet end to the outlet end and a plurality of passages defined by internal walls of the substrate extending therethrough, and over x % of the substrate axial length from the inlet end to the outlet end of the substrate, wherein x ranges from 80 to 100;
• calcining the substrate having the first aqueous mixture disposed thereon, obtaining a substrate comprising a coating comprising a zeolitic material comprising copper;
• (iii) preparing a second aqueous mixture comprising only water and an iron salt;
• (iv) disposing only the second aqueous mixture obtained according to (iii) on the substrate obtained according to (ii) over y % of the substrate axial length from the inlet end to the outlet end of the substrate, wherein y ranges from 10 to x, obtaining a substrate comprising, in a first zone, the coating comprising a zeolitic material comprising copper and over y of the substrate axial length the iron salt;
• and, if x>y, in a second zone extending from y % to x of the substrate axial length from the inlet end to the outlet end, the coating comprising the zeolitic material comprising copper, wherein the iron salt is one or more of iron (III) nitrate, iron (II) acetate, ammonium iron (III) citrate, iron (II) sulfate, and iron (II) oxalate, wherein (iv) is performed by dipping the substrate obtained according to (ii) into the second aqueous mixture prepared in (iii);
• and
• (v) calcining the substrate obtained according to (iv).