Catalyst for enhanced high temperature conversion and reduced n2o make

A process for preparing a catalyst for the treatment of an exhaust gas of a diesel engine, comprising

• (i) preparing an aqueous mixture comprising water, a zeolitic material comprising Fe and having a framework structure type selected from the group consisting of CHA, AEI, RTH, LEV, DDR, KFI, ERI, AFX, a mixture of two or more thereof and a mixed type of two or more thereof, wherein the framework structure of the zeolitic material comprises Si, Al and O, the aqueous mixture further comprising a source of Cu and a first non-zeolitic oxidic material selected from the group consisting of alumina, silica, titania, zirconia, ceria, lanthana, praseodymium oxide, manganese oxide, a mixed oxide comprising one or more of Al, Si, Ti, Zr, La, Mn, Pr, and Ce, and a mixture of two or more thereof,
• wherein the aqueous mixture exhibits a weight ratio of Fe comprised in the zeolitic material, calculated as Fe2O3, relative to Cu comprised in the copper source, calculated as CuO, Fe2O3:CuO, of less than 0.1:1;
• (ii) disposing the aqueous mixture obtained in (i) on the surface of the internal walls of a substrate comprising 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, over at least 55% of the substrate axial length;
• (iii) subjecting the substrate obtained in (ii) to a heat treatment in a gas atmosphere;
• obtaining the catalyst.