Abstract: The present invention provides a thermally stable catalyst for treating automobile exhaust by-products is provided. The catalyst of the invention comprises a first section that includes a precious metal present in a first concentration and a second section that includes a precious metal present in a second concentration. The catalyst of the invention is characterized by a unique precious metal concentration profile in which the first concentration of the precious metal is lower than the second concentration of the precious metal. When placed with an automobile exhaust system, the second section is positioned downstream of the first section. The present invention also provides a lean NOx trap utilizing the unique precious metal concentration profile. The NOx trap is found to possess improved NOx conversion performance relative to a NOx trap with the same total amount of precious metal deposited uniformly over the volume of the trap.

Abstract: A lean NOx trap composition. The lean NOx trap composition utilizes ruthenium in place of higher cost metals such as platinum. The lean NOx trap composition provides high NOx storage efficiency and high NOx conversion efficiency when incorporated in a lean NOx trap. A method of removing harmful gases using the lean NOx trap composition is also described.

Abstract: A lean NOx trap composition. The lean NOx trap composition utilizes ruthenium in place of higher cost metals such as platinum. The lean NOx trap composition provides high NOx storage efficiency and high NOx conversion efficiency when incorporated in a lean NOx trap. A method of removing harmful gases using the lean NOx trap composition is also described.

Abstract: The present invention provides a catalyst for use in a NOx trap that has reduced NOx release during rich purges, increased NO conversion efficiency under stoichiometric conditions, and improved sulfur tolerance. The catalyst of this embodiment includes a precious metal, an oxygen storage component in contact with the precious metal, and a NOx storage material. The oxygen storage component in contact with the precious metal is present in an amount that provides sufficient oxygen storage capacity to reduce the NOx release from the NOx trap during rich purges to less than 20% of the NOx that is stored in the NOx trap across the operating temperature window of the NOx trap, increase the NOx conversion efficiency under stoichiometric conditions to a value greater than 70%, and increase the sulfur tolerance of the NOx trap.

Abstract: The present invention provides a method of removing harmful gases from an automobile exhaust. The method of the invention comprises contacting a thermally stable NOx trap composition with a first exhaust gas mixture at a temperature of at least 200° C. The first exhaust gas mixture includes exhaust gases from an internal combustion engine operating in a fuel-lean condition. After, NOx has been absorbed onto the NOx absorber material, the NOx trap composition is then contacted with a second exhaust gas composition. In this step, the second exhaust gas mixture includes exhaust gases from an internal combustion engine operating in a fuel-rich condition. The present invention also provides the NOx trap composition used in the method. The NOx trap of the invention includes a precious metal, a NOx absorber material, an oxide that inhibits the decrease in NOx storing ability of the NOx trap composition, and a support material.