Catalyst for gasoline lean burn engines with improved NO oxidation activity

A method for producing an oxidation catalyst for the oxidation of NO and hydrocarbons, the method comprising the steps of:

• (i) providing a substrate;
• (ii) impregnating one or more particulate support materials with at least one Pt- and/or at least one Pd-source;
• (iii) adding one or more oxygen storage component (OSC) materials, one or more nitrogen oxide storage materials comprising one or more elements selected from the group of alkali and/or alkaline earth metals, and a solvent to the product obtained in step (ii) to obtain a slurry;
• (iv) milling the slurry obtained in step (iii);
• (v) providing the resulting slurry of step (iv) onto the substrate in one or more coating steps as a layer;
• (vi) optionally repeating steps (ii) to (v) one or more times;
• (vii) impregnating one or more particulate support materials with at least one Pt-source;
• (viii) adding one or more oxygen storage component (OSC) materials, one or more nitrogen oxide storage materials comprising one or more elements selected from the group of alkali and/or alkaline earth metals, and a solvent to the product obtained in step (vii) to obtain a slurry;
• (ix) milling the slurry obtained in step (viii);
• (x) providing the resulting slurry of step (ix) onto the coated substrate in one or more coating steps as a layer;
• wherein the total amount of alkali and alkaline earth metals comprised in the one or more nitrogen oxide storage materials contained in the catalyst ranges from 0.18 to 2.5 g/in3 calculated as the respective alkali metal oxides M2O and alkaline earth metal oxides MO,
• wherein Rh is contained in the catalyst in an amount of 1 g/ft3 or less.