Zero-PGM Catalyst with Oxygen Storage Capacity for TWC Systems
ZPGM-ZRE catalyst system substantially free from platinum group (PGM) and rare earth (RE) metals for TWC application is disclosed. Disclosed ZPGM-ZRE catalyst system may include pure alumina as washcoat and a Cu—Mn stoichiometric spinel with Nb 2 O 5 —ZrO 2 support oxide, as ZPGM-ZRE catalyst in overcoat. Disclosed ZPGM-ZRE catalyst systems are found to have high thermal stability, catalyst activity, and high oxygen storage capacity compared to commercial PGM catalyst system that includes Ce-based oxygen storage material (OSM).
1 . A catalyst system, comprising:
a substrate;
a washcoat;
an overcoat comprising at least one oxygen storage material is substantially free of platinum group metals and rare earth metals; and
wherein the at least one oxygen storage material comprises Cu—Mn spinel having a niobium-zirconia support oxide; and
wherein the washcoat comprises Al 2 O 3 .
2 . The catalyst system of claim 1 , wherein the Cu—Mn spinel comprises CuMn 2 O 4 .
3 . The catalyst system of claim 1 , wherein the niobium-zirconia support oxide comprises Nb 2 O 5 —ZrO 2 .
4 . The catalyst system of claim 1 , wherein the at least one oxygen storage material is calcined at about 600° C.
5 . The catalyst system of claim 1 , wherein the calcination is for about 5 hours.
6 . The catalyst system of claim 1 , wherein the niobium-zirconia support oxide comprises about 15% to about 30% by weight of Nb 2 O 5 .
7 . The catalyst system of claim 1 , wherein the niobium-zirconia support oxide comprises about 25% by weight of Nb 2 O 5 .
8 . The catalyst system of claim 1 , wherein the niobium-zirconia support oxide comprises about 70% to about 85% by weight of ZrO 2 .
9 . The catalyst system of claim 1 , wherein the niobium-zirconia support oxide comprises about 75% by weight of ZrO 2 .
10 . The catalyst system of claim 1 , wherein the at least one oxygen storage material is deposited on the substrate at about 120 g/L.
11 . The catalyst system of claim 1 , wherein the Cu—Mn spinel comprises about 10 g/L to about 15 g/L of Cu.
12 . The catalyst system of claim 2 , wherein the Cu—Mn structure comprises about 20 g/L to about 25 g/L of Mn.
13 . The catalyst system of claim 1 , wherein the niobium-zirconia support oxide is deposited on the substrate at about 80 g/L to about 90 g/L.
14 . The catalyst system of claim 1 , wherein the at least one oxygen storage material is at least partially aged.
15 . The catalyst system of claim 1 , wherein the at least one oxygen storage material is applied to the substrate by co-precipitation.
16 . The catalyst system of claim 1 , wherein the at least one oxygen storage material stores O 2 at a concentration of about 8,000 ppm.
17 . The catalyst system of claim 1 , wherein the at least one oxygen storage material stores CO at a concentration of about 8,000 ppm.
18 . The catalyst system of claim 1 , wherein the R value is about 1.05.
19 . The catalyst system of claim 18 , wherein the conversion of NO is about 88%.
20 . The catalyst system of claim 1 , wherein the R value is about 1.1.
21 . The catalyst system of claim 20 , wherein the conversion of NO is about 100%.
22 . The catalyst system of claim 1 , wherein the R value is about 1.158.
23 . The catalyst system of claim 1 , wherein the R value is about 1.04.
21 . The catalyst system of claim 23 , wherein the conversion of NO and HC is about 65%.