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US 9,517,434 B2Granted
Catalyst system for exhaust gas purification utilizing base metals, and controlling method therefor
AssigneeToyota Jidosha Kabushika Kaisha
InventorTakeshi Nobukawa
Life of this patent
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Abstract
A catalyst system for exhaust gas purification which comprises a first-stage base metal catalyst located upstream and a second-stage base metal catalyst located downstream, wherein the first-stage base metal catalyst comprises at least one oxide support selected from the group consisting of alumina, ceria, zirconia, yttria, and titania and Cu metal and/or a Cu oxide supported thereon, and in cases where the amount of NOx in the exhaust gas has become or exceeded an NOx criterion, the state of the exhaust gas is switched from slightly rich to rich.
Claims12
A catalyst system for exhaust gas purification comprising:
- an electronic control unit (ECU);
- a first-stage metal catalyst located at an upstream end;
- and a second-stage base metal catalyst located at a downstream end, wherein the first-stage metal catalyst has Cu metal and/or Cu oxide supported on one or more oxide supports selected from the group consisting of alumina, ceria, zirconia, yttria and titania, wherein the crystallite diameter for ceria-zirconia of the oxide supports is 4 nm-12 nm, and wherein when the volume of NOx in the exhaust gas has become equal to or exceeds an NOx criteria, the ECU switches the state of the exhaust gas from slightly enriched of 14.45≦A/F1≦−14.59 to enriched of A/F2≦14.40.
Dependencies are inferred from the claim text.