Abstract: An automobile exhaust system includes a catalytic converter and a modified NOx trap wit improved sulfur tolerance. Sulfur oxide has a deleterious effect on the performance of nitrogen oxide traps. In the modified NOx trap, a sulfur oxide trap is integrated with a nitrogen oxide trap by coating the catalyst contained within a nitrogen oxide trap with a mixed oxide layer of calcium oxide and magnesium oxide. The NOx trap is regenerated by heating at elevated temperature for a short time period.

Abstract: An automobile exhaust system includes a catalytic converter, a NOx trap, and a sulfur oxide trap. The sulfur oxide trap improves the efficiency of the NOx trap. Sulfur oxide has a deleterious effect on the performance of nitrogen oxide traps. The sulfur oxide trap comprises a monolithic substrate which is over-coated with an aluminum oxide layer and a mixed oxide layer of calcium oxide and magnesium oxide. In a variation, a sulfur oxide trap is integrated with a nitrogen oxide trap by coating the catalyst contained within a nitrogen oxide trap with a mixed oxide layer of calcium oxide and magnesium oxide. In each embodiment, the sulfur oxide trap can be regenerated by heating at elevated temperature for a short time period.

Abstract: The present invention disclose a sulfur oxide trap that may be used to improve efficiency of a nitrogen oxide trap. Sulfur oxide has a deleterious effect on the performance of nitrogen oxide traps. The sulfur oxide trap of the present invention, comprises a monolithic substrate which is over-coated with an aluminum oxide layer and a mixed oxide layer of calcium oxide and magnesium oxide. In another embodiment of the invention, the sulfur oxide trap is integrated with a nitrogen oxide trap by coating the catalyst contained within a nitrogen oxide trap with a mixed oxide layer of calcium oxide and magnesium oxide. In each embodiment of the invention, the sulfur oxide trap can be regenerated by heating at elevated temperature for a short time period.

Abstract: An integrated lean NOx trap. The integrated lean NOx trap includes a lean NOx trap containing a composite metal oxide mixture consisting essentially of about 80-100 wt % stoichiometric spinel MgAl2O4 and between about 0-20 wt % of CeO2 or CeO2—ZrO2. A method for removing NOx and SOx impurities from exhaust gases using the integrated lean NOx trap is also described.

Abstract: The present invention provides a composition and method for storing and reducing NOx for lean burn internal combustion engines. The present invention uses composite metal oxides, in spinel structure, in conjunction with a typical LNT formulation to form an integrated LNT. The composite metal oxides in spinel structure act primarily as a SOx trapping element and also a secondarily NOx trapping element within the integrated LNT. In this integrated LNT, the sulfur is trapped and released in a way that does not allow the sulfur to go to the primary NOx trapping element, i.e. the alkali or alkali earth metal oxides, to poison the integrated LNT; thereby, leaving more reactive sites for the NOx trapping and conversion.

Abstract: The invention is a method of treating exhaust gases generated by an internal combustion engine using a NOx trap in the exhaust flow system. The method comprises locating a nitrogen oxide trap in the exhaust gas passage and cycling the air/fuel ratio of the exhaust gases entering the trap between lean and rich, such that the trap absorbs nitrogen oxides during the lean cycle and desorbs the nitrogen oxides when the concentration of the oxygen in the exhaust flow is lowered as during a rich cycle. The trap comprises: (a) a porous support material comprising mostly &ggr;-alumina; (b) a sulfur-suppressing metal selected from the group consisting of cesium, zinc and a combination of cesium and zinc; (c) a precious metal; and (d) a NOx sorption metal such as barium, the metals being deposited in the support material, the amount of the metals being individually dependent on the weight of the support material.