Catalyst with improved hydrothermal stability
A catalyst for the treatment of exhaust gas emissions is disclosed. The catalyst can comprise ceria-alumina particles having a ceria phase present in a weight percent of the composite in the range of about 20% to about 80% on an oxide basis, an alkaline earth metal component supported on the ceria-alumina particles, wherein the CeO 2 is present in the form of crystallites that are hydrothermally stable and have an average crystallite size less than 160 Å after aging at 950° C. for 5 hours in 2% O 2 and 10% steam in N 2 .
1. An emission treatment system comprising:
a catalyst including a catalyst composition comprising ceria-alumina particles having a ceria phase present in a weight percent of the particles in the range of about 20% to about 80% on an oxide basis, an alkaline earth metal component supported on the ceria-alumina particles, wherein the CeO 2 is present in the form of crystallites that are hydrothermally stable and have an average crystallite size of less than 160 Å after aging at 950° C. for 5 hours in 2% O 2 and 10% steam in N 2 ; a lean burn engine located upstream from the catalyst composition; and a second, different catalyst.
2. The emission treatment system of claim 1 , further comprising a particulate filter.
3. The emission treatment system of claim 1 , wherein the second, different catalyst is selected from a three-way catalyst (TWC), a gasoline particulate filter (GPF), a selective catalytic reduction (SCR) catalyst, a lean NO x trap (LNT), an ammonia oxidation (AMOX) catalyst, a SCR on a filter (SCRoF), and combinations thereof.
4. The emission treatment system of claim 1 , wherein the alkaline earth metal component comprises a barium component.
5. The emission treatment system of claim 4 , wherein the barium component is selected from the group consisting of barium oxide and barium carbonate.
6. The emission treatment system of claim 4 , further comprising at least one platinum group metal selected from the group consisting of platinum, palladium, rhodium, iridium, and mixtures thereof, supported on the ceria-alumina particles.
7. The emission treatment system of claim 6 , wherein the platinum group metal is selected from platinum, palladium, rhodium, and mixtures thereof.
8. The emission treatment system of claim 6 , wherein the platinum group metal consists essentially of platinum and palladium.
9. The emission treatment system of claim 6 , wherein the platinum group metal consists essentially of platinum.
10. The emission treatment system of claim 4 , wherein the barium component is present in an amount in of about 0.5% to 50% by weight on an oxide basis.
11. The emission treatment system of claim 10 , wherein the barium component is present in an amount of about 5% to 30% by weight on an oxide basis.
12. The emission treatment system of claim 1 , wherein the ceria-alumina particles are a composite of ceria and alumina.
13. The emission treatment system of claim 12 , wherein the composite of ceria and alumina contains ceria in an amount of about 30% to 80% by weight on an oxide basis.
14. The emission treatment catalyst of claim 12 , wherein the composite of ceria and alumina contains ceria in an amount of about 50% to 80% by weight on an oxide basis.