System and method for purifying exhaust gases

System of any of the above claims, characterized in that the exhaust gas discharge line of each cylinder of the engine is connected to a connecting channel (2) wherein said operational units are arranged.

System of any of the above claims, characterized in that the oxidation catalyst (3, 3′) contains platinum and/or palladium as catalytic metal(s).

System for purifying exhaust gases of diesel or gasoline engines containing on average an excess of oxygen, characterized in that this system includes NOx adsorption catalysts that are arranged in each exhaust gas discharge line of each cylinder or in each of the exhaust gas discharge lines of two cylinders.

System of any of the above claims, characterized in that the regeneration of the NOx adsorption catalyst sulfates, the reduction of nitrates and burning of particles is accomplished by periodically using a lean mixture and a rich mixture.

System of any of the above claims, characterized in that said NOx adsorption catalyst (5, 5′, 5″) contains as a catalytic metal platinum and/or rhodium and at least one of the following elements:

• Ba, Sr, La, Y, Ce, Zr, and possibly at least one of the following elements:
• Li, Na, K, Rb, Cs, Be, Mg, Ca.

Method for purifying exhaust gases of diesel or gasoline engines containing on average an excess of oxygen, characterized in that the exhaust gases to be purified are passed over an NOx adsorption catalyst allowing for the regeneration of sulfates with a lean-rich mixture, the ratio of the duration of the lean phase to that of the rich phase being more than 3, preferably more than 10.

Method for purifying exhaust gases of diesel or gasoline engines containing on average an excess of oxygen, characterized in that the exhaust gases to be purified are passed over an NOx adsorption catalyst wherein the regeneration of nitrates, sulfates and particles is achieved by periodically adjusting the mixing ratio of the engine from lean to a ratio closer to stoichiometric, the λ value being preferably below 1.2 and more preferably below 1.15.