Patent ID: 6852666

Claim:
A composition for purifying the exhaust gases of an internal combustion engine that is able to carry out the combustion of a fuel with lean air/fuel ratios, comprising means which absorb NOR present in the exhaust gases, in the presence of excess oxygen, and which release the absorbed NO x when the oxygen concentration of the exhaust gases decreases, wherein the means absorbing the NO x are adapted to be deposited on a substrate and comprise a combination of: a first composition comprising a support, the support for the first composition being based on an oxide chosen from cerium oxide, zirconium oxide or mixtures thereof, and an active phase, the active phase being based on manganese and on at least one other element A selected from alkali metals and alkaline-earth metals, the manganese and the element A being chemically bonded to each other, a second composition comprising a support based on alumina or alumina stabilized by silicon, zirconium, barium or a rare earth, or silica and an active phase based on manganese and on at least one other element B selected from the alkali metals, alkaline-earth metals and rare earths, this second composition having, or being capable of having, a specific surface area of at least 80 m 2 /g after calcination for 8 hours at 800° C., and in that, furthermore, a reduction and/or three-way-catalyst function is incorporated into the means absorbing the NO x .