초록

New three-way catalysts for vehicles contain, as an oxygen storage component, mixed oxide MnZr. These components are less expensive than state-of-the-art ceria/zirconia, and generally offer improved capacity even after exposure to high temperatures.

대표청구항 ▼

1. A vehicle comprising a substantially stoichiometrically operated engine comprising an exhaust system wherein said exhaust system comprises a three-way catalyst comprising an oxygen storage component comprising a manganese/zirconium mixed oxide obtained by co-precipitation, sol/gel or gel precipit

1. A vehicle comprising a substantially stoichiometrically operated engine comprising an exhaust system wherein said exhaust system comprises a three-way catalyst comprising an oxygen storage component comprising a manganese/zirconium mixed oxide obtained by co-precipitation, sol/gel or gel precipitation, wherein the molar ratio of said mixed oxide is in the range of 50:50 to 70:30 manganese:zirconium and said mixed oxide has a surface area below 10 m2/g. 2. A catalyst according to claim 1, wherein said mixed oxide contains manganese in an oxidation state higher than 2. 3. A catalyst according to claim 1 or 2, wherein said oxygen storage component further comprises at least one dopant in a total amount of 5 to 30 mol % based on ZrO2content. 4. A catalyst according to claim 3, wherein said dopant is selected from a group consisting of ceria, and the oxides of neodymium, praseodymium, lanthanum, yttrium, niobium, titanium and vanadium. 5. A catalyst according to claim 3, wherein said at least one dopant consists of ceria. 6. A catalyst according to claim 1 or 2, further comprising a catalytically-active metal selected from at least one of platinum and palladium. 7. A catalyst according to claim 6, wherein said catalytically-active metal further comprises rhodium. 8. A vehicle according to claim 1, wherein said mixed oxide is in the form of an intimate physical mixture of manganese oxide and zirconium oxide. 9. A vehicle comprising a substantially stoichiometrically operated engine comprising an exhaust system wherein said exhaust system comprises a three-way catalyst comprising an oxygen storage component consisting essentially of a manganese/zirconium mixed oxide obtained by co-precipitation, sol/gel or gel precipitation, wherein the molar ratio of said mixed oxide is in the range of 50:50 to 70:30 manganese:zirconium and said mixed oxide has a surface area below 10 m2/g. 10. A vehicle according to claim 9, wherein said mixed oxide is in the form of an intimate physical mixture of manganese oxide and zirconium oxide. 11. The vehicle according to claim 1 or 9, wherein the surface area of said mixed oxide is below 5 m2/g. 12. An exhaust system comprising a three-way catalyst comprising an oxygen storage component consisting essentially of a manganese/zirconium mixed oxide obtained by co-precipitation, sol/gel or gel precipitation, wherein the molar ratio of said mixed oxide is in the range of 50:50 to 70:30 manganese:zirconium and said mixed oxide has a surface area below 10 m2/g. 13. An exhaust system according to claim 12, wherein said mixed oxide is in the form of an intimate physical mixture of manganese oxide and zirconium oxide. 14. The exhaust system according to claim 12, wherein the surface area of said mixed oxide is below 5 m2/g. 15. A substantially stoichiometrically operated engine comprising an exhaust system comprising a three-way catalyst comprising an oxygen storage component consisting essentially of a manganese/zirconium mixed oxide obtained by co-precipitation, sol/gel or gel precipitation, wherein the molar ratio of said mixed oxide is in the range of 50:50 to 70:30 manganese:zirconium and said mixed oxide has a surface area below 10 m2/g. 16. An engine according to claim 15, wherein said mixed oxide is in the form of an intimate physical mixture of manganese oxide and zirconium oxide. 17. The engine according to claim 15, wherein the surface area of said mixed oxide is below 5 m2/g.