초록 ▼

A NOx storage component comprises caesium silicate (Cs2SiO3) and at least one platinum group metal. The invention also includes a NOx absorber catalyst comprising a NOx storage component according to the invention disposed on a substrate monolith; a method of treating exhaust gas containing NOx from

A NOx storage component comprises caesium silicate (Cs2SiO3) and at least one platinum group metal. The invention also includes a NOx absorber catalyst comprising a NOx storage component according to the invention disposed on a substrate monolith; a method of treating exhaust gas containing NOx from a lean burn internal combustion engine comprising the steps of contacting a NOx storage component comprising caesium silicate (Cs2SiO3) and at least one platinum group metal with lean exhaust gas containing NOx to adsorb NOx thereon; and periodically desorbing adsorbed NOx by contacting the NOx storage component with stoichiometric or rich exhaust gas; and a method of making a NOx storage component according to the invention comprising the steps of combining and reacting an aqueous salt of at least one platinum group metal, an aqueous caesium salt and a source of silica.

대표청구항 ▼

1. A NOx absorber catalyst comprising two or more layers disposed on a substrate monolith, wherein a first layer comprises a NOx storage component comprising caesium silicate (Cs2SiO3) and at least one platinum group metal; and a second layer comprises at least one alkaline earth metal. 2. The NOx a

1. A NOx absorber catalyst comprising two or more layers disposed on a substrate monolith, wherein a first layer comprises a NOx storage component comprising caesium silicate (Cs2SiO3) and at least one platinum group metal; and a second layer comprises at least one alkaline earth metal. 2. The NOx absorber catalyst of claim 1, wherein the first layer is disposed above the second layer. 3. The NOx absorber catalyst of claim 1, wherein platinum, palladium or both platinum and palladium are disposed in the second layer. 4. The NOx absorber catalyst of claim 1, wherein the first layer comprises the caesium silicate and the at least one platinum group metal supported on a refractory metal oxide support. 5. The NOx absorber catalyst of claim 4, wherein the refractory metal oxide support is selected from the group consisting of alumina, silica, titanic, zirconia, cerin, magnesia and mixtures, mixed oxides or composite oxides of any two or more thereof. 6. The NOx absorber catalyst of claim 4, wherein the refractory metal oxide support is doped with one or more of silica and rare earths. 7. The NOx absorber catalyst of claim 4, wherein the refractory metal oxide support also supports a rare earth oxide. 8. The NOx absorber catalyst of claim 7, wherein the rare earth oxide is cerin. 9. The NOx absorber catalyst of claim 1, wherein the at least one platinum group metal is selected from the group consisting of platinum, palladium, rhodium, and mixtures of two or more thereof. 10. The NOx absorber catalyst of claim 1, wherein the platinum group metal is rhodium. 11. The NOx absorber catalyst of claim 1, wherein the NOx storage component additionally comprises manganese. 12. The NOx absorber catalyst of claim 1, wherein the NOx storage component is produced by a method comprising the steps of combining and reacting an aqueous salt of at least one platinum group metal, an aqueous caesium salt and a source of silica. 13. An exhaust system for a lean-burn internal combustion engine comprising the NOx absorber catalyst of claim 1. 14. A motor vehicle comprising the exhaust system of claim 13. 15. A method of treating exhaust gas containing NOx from a lean burn internal combustion engine, which method comprising the steps of contacting a NOx absorber catalyst with lean exhaust gas containing NOx to adsorb NOx thereon; and periodically desorbing adsorbed NOx by contacting the NOx absorber catalyst with stoichiometric or rich exhaust gas, wherein the NOx absorber catalyst comprises two or more layers disposed on a substrate monolith, wherein a first layer comprises a NOx storage component comprising caesium silicate (Cs2SiO3) and at least one platinum group metal; and a second layer comprises at least one alkaline earth metal.