Nitrous oxide removal catalysts for exhaust systems
A nitrous oxide (N 2 O) removal catalyst composite is provided, comprising a N 2 O removal catalytic material on a substrate, the catalytic material comprising a rhodium (Rh) component supported on a ceria-based support, wherein the catalyst composite has a H 2 -consumption peak of about 100° C. or less as measured by hydrogen temperature-programmed reduction (H 2 -TPR). Methods of making and using the same are also provided.
1. A method of making a nitrous oxide (N 2 O) removal catalyst composite, the method comprising:
depositing a rhodium precursor onto a fresh ceria-based support having a pore volume of at least about 0.20 cm 3 /g and forming a washcoat therefrom;
coating a substrate comprising a flow-through monolith or a wall-flow filter with the washcoat to form a coated substrate; and
calcining the coated substrate in air at a temperature between about 600° C. and about 800° C. for at least 10 hours.
2. The method of claim 1 , wherein the calcining step is carried out under conditions of 750° C. for 20 hours with 10 weight % water in air.
3. The method of claim 1 , further comprising:
calcining the fresh ceria-based support at about 600° C. to about 800° C. before the depositing step.
4. The method of claim 1 , wherein the temperature is 750° C.
5. The method of claim 1 , wherein the calcining step is carried out for about 10 to about 30 hours.
6. The method of claim 1 , wherein the calcining step is carried out for about 20 hours.