Active perovskite-type catalysts stable to high temperature aging for gasoline exhaust gas applications
Compositions, articles, and methods related to a three-way-catalyst composition comprising a perovskite-type compound of formula (I): La z B 1-q B′ q O 3±δ or formula (II):[BO x ] y :[La z BO 3±δ ] 1-y and a non-redox active component; wherein B or B′ is Fe, Mn, Co, Ni, Cu, Ti, or Zr; q is in a range from about 0 to about 0.5; x is from about 1 to about 2.5; y is from about 1 to about 30 wt %; z is about 0.6 to about 1.1; δ is in a range from about 0 to about 0.6.
1. A three-way catalyst composition comprising a perovskite-type compound of formula (I): La z B 1-q B′ q O 3±δ or formula (II): [BO x ] y :[La z BO 3±δ ] 1-y and a non-redox active component; wherein
B or B′ is Fe, Mn, Co, Ni, Cu, Ti, or Zr;
q is in a range from 0 to 0.5;
δ is in a range from 0 to 0.6;
x is from 1 to 2.5;
y is from 1 to 30 wt %;
z is 0.6 to 1.1; and
wherein the perovskite-type compound has high surface area of at least 40 m 2 /g.
2. The three-way catalyst composition of claim 1 , wherein the perovskite-type compound is the compound of formula (I): La z BO 3±δ .
3. The three-way catalyst composition of claim 2 , wherein B is Fe.
4. The three-way catalyst composition of claim 2 , wherein B is Mn.
5. The three-way catalyst composition of claim 1 , wherein the perovskite-type compound is the compound of formula (II): [BO x ] y :[La z BO 3±δ ] 1-y .
6. The three-way catalyst composition of claim 5 , wherein B is Mn.
7. The three-way catalyst composition of claim 1 , wherein the non-redox active component comprises an oxide.
8. The three-way catalyst composition of claim 1 , wherein the non-redox active component comprises alumina.
9. The three-way catalyst composition of claim 1 , wherein the non-redox active component comprises ZrO 2 .
10. The three-way catalyst composition of claim 9 , wherein the ZrO 2 is doped.
11. The three-way catalyst composition of claim 1 , wherein the catalyst is substantially free of platinum group metals.
12. The three-way catalyst composition of claim 1 , wherein the catalyst is free of platinum group metals.
13. The three-way catalyst composition of claim 1 , wherein the perovskite-type compound is present in an amount of 5 wt % to 75 wt % of the catalyst composition.
14. The three-way catalyst composition of claim 1 , wherein the non-redox active component is present in an amount of 25 wt % to 95 wt % of the catalyst composition.
15. The three-way catalyst composition of claim 1 , wherein the perovskite-type compound and the non-redox active component are present in a weight ratio of 0.5:1 to 3:1.
16. A catalyst article for treating exhaust gas, comprising:
a. a substrate; and
b. the three-way-catalyst composition of claim 1 .
17. A method of treating an exhaust gas from an internal combustion engine, comprising contacting the exhaust gas with a catalyst article comprising a substrate and the three-way-catalyst composition of claim 1 .
18. The method of claim 17 , wherein the three-way-catalyst composition provides:
(1) a fresh NO conversion at 500-600° C., and
(2) an aged NO conversion at 500-600° C. after aging the catalyst at a temperature of at least 700° C. for 20 hours in the presence of steam,
wherein a delta between the fresh NO conversion and the aged NO conversion is a decrease of less than 20%.
19. The method of claim 17 , wherein the three-way-catalyst composition provides:
(1) a fresh HC or CO conversion at 500° C., and
(2) an aged HC or CO conversion at 500° C. after aging the catalyst at a temperature of at least 700° C. for 20 hours in the presence of steam,
wherein a delta between the fresh HC or CO conversion and the aged HC or CO conversion is a decrease of less than 50%.