Process for the Removal of Harmful Substances from Exhaust Gases of Combustion Engines and Catalyst for Carrying Out Said Process

Use of catalytic components for a catalytic process for the removal of NOx from the exhaust gases of lean engines in the cyclic lean/rich operational mode, which comprises at least the following partial steps:

• (i) storing of NOx under lean exhaust gas conditions in at least one NOx-storing component,
• (ii) in situ conversion of the stored NOx to ammonia (NH3) under rich exhaust gas conditions,
• (iii) storing of the NH3 in at least one NH3-storing component under rich exhaust conditions,
• (iv) reaction of NH3 with NOx under lean exhaust gas conditions,
• wherein the partial steps of storing of NOx and reaction of NH3 run at least temporarily and/or partially simultaneously and/or parallelly, characterized in that the catalytic components which cause said partial steps (i) to (iv) are in a physical contact.

Use of catalytic components containing at least one of the materials from the group (1) and at least one acidic solid from the group (2):

• (1) Pt, Pd, Rh, Ir and Ru, each alone or in mixture, being present on a carrier material selected from:
• oxides, mixed oxides, phosphates and sulfates of Al, Si, Zr, Ti, Ce, the earth alkali metal elements and rare earth elements;
• heteropoly acids;
• zeolites;
• as well as mixtures thereof;
• (2) zeolites, heteropoly acids, sulfated zirconium oxides or zirconium phosphates;
• as well as mixtures thereof;
• for a catalytic process for the removal of NO from the exhaust gases of lean engines in the cyclic lean/rich operational mode, which comprises at least the following partial steps:
• (i) storing of NOx under lean exhaust gas conditions in at least one NOx-storing component,
• (ii) in situ conversion of the stored NO to ammonia (NH3) under rich exhaust gas conditions,
• (iii) storing of the NH3 in at least one NH3-storing component under rich exhaust conditions,
• (iv) reaction of NH3 with NOx under lean exhaust gas conditions,
• wherein the partial steps of “storing of NOx” and “reaction of NH3” run at least temporarily and/or partially simultaneously and/or parallelly, characterized in that the catalytic components which cause said partial steps (i) to (iv) are in a physical contact.