Catalyst compositions, articles, methods and systems
Described are catalyst compositions, catalytic articles, exhaust gas treatment systems and methods that utilize the catalytic articles. The catalyst composition comprises a washcoat including a zeolite, refractory metal oxide support particles, and a platinum group metal supported on the refractory metal oxide support particles. Greater than 90% of the refractory metal oxide particles supporting PGM have a particle size greater than 1 μm and a d 50 less than 40 microns.
1. A catalyst composition comprising a washcoat including a zeolite, refractory metal oxide support particles, and a platinum group metal supported on the refractory metal oxide support particles, wherein greater than 90% of the refractory metal oxide particles supporting PGM have a particle size greater than 1 μm and a d 50 less than 40 microns.
2. The catalyst composition of claim 1 , wherein greater than 95% of the refractory metal oxide particles supporting PGM have a particle size greater than 1 μm and a d 50 less than 40 microns.
3. The catalyst composition of claim 2 , where greater than 98% of the refractory metal oxide particles supporting PGM have a particle size greater than 1 μm and a d 50 less than 40 microns.
4. The catalyst composition of claim 1 , wherein the refractory metal oxide support particles are selected from alumina, silica-alumina, titania, titania-alumina, silicatitania, ceria, ceria-alumina, ceria-silica-alumina, manganese-alumina, and lanthanaalumina.
5. The catalyst composition of claim 4 , wherein the refractory metal oxide support particles are selected from alumina and silica-alumina.
6. The catalyst composition of claim 1 , wherein the CO light-off temperature of the catalyst composition after aging at 800° C. is at least 3° C. less than the light-off temperature of a catalyst composition comprising refractory metal oxide support particles and a platinum group metal supported on the refractory metal oxide support particles, wherein less than 90% of the refractory metal oxide support particles of the comparative catalyst composition have a particle size greater than 1 μm.
7. The catalyst composition of claim 6 , wherein the CO light-off temperature of the catalyst composition after aging at 800° C. is at least 5° C. less than the light-off temperature of a comparative catalyst composition comprising refractory metal oxide support particle and a platinum group metal supported on the refractory metal oxide support particles, wherein less than 90% of the refractory metal oxide support particles of the comparative catalyst composition have a particle size greater than 1 μm.
8. The catalyst composition of claim 7 , wherein the CO light-off temperature of the catalyst composition after aging at 800° C. is at least 7° C. less than the light-off temperature of a comparative catalyst composition comprising refractory metal oxide support particles and a platinum group metal supported on the refractory metal oxide support particles, wherein less than 90% of the refractory metal oxide support particles of the comparative catalyst composition have a particle size greater than 1 μm.
9. The catalyst composition of claim 1 , wherein the platinum group metal comprises platinum, palladium, or mixtures thereof.
10. The catalyst composition of claim 1 , wherein the zeolite is selected from the group consisting of faujasite, chabazite, clinoptilolite, mordenite, silicalite, zeolite X, zeolite Y, ultrastable zeolite Y, ZSM-5, ZSM-12, SSZ-13, SAPO-5, SAPO-37, offretite, Beta zeolite, and combinations thereof.
11. The catalyst composition of claim 10 , wherein the zeolite is Beta zeolite.
12. The catalyst composition of claim 10 , wherein the zeolite has a particle size distribution that is monomodal.
13. A catalytic article for the treatment of exhaust gas from an internal combustion engine containing hydrocarbons, carbon monoxide, and nitrogen oxides, the catalytic article comprising a carrier substrate having a length, an inlet end and outlet end, an oxidation catalyst material on the carrier, the oxidation catalyst material including an oxidation catalyst comprising a washcoat layer including the catalyst composition of claim 1 .
14. The catalytic article of claim 13 , wherein the catalytic article uses a single washcoat layer.
15. The catalytic article of claim 13 , wherein the internal combustion engine is a lean burn engine.
16. A method of treating exhaust gas from a lean burn engine containing hydrocarbons, carbon monoxide, and nitrogen oxides, the method comprising flowing the exhaust gas over the catalytic article of claim 13 .
17. A method of preparing a catalytic article including a zeolite, refractory metal oxide support particles, and a platinum group metal supported on the refractory metal oxide support particles, wherein greater than 90% of the refractory metal oxide particles supporting PGM have a particle size greater than 1 μm and a d 50 less than 40 microns, the method comprising impregnating refractory metal oxide support particles with a platinum group metal, spray drying the refractory metal oxide particles supporting PGM to increase the particle size, creating a slurry of the spray dried refractory metal oxide particles supporting PGM, adding the zeolite to the slurry to form a washcoat, and coating the washcoat on a substrate.