Perovskite catalyst system for lean burn engines
AssigneeFord Global Technologies, LLC
InventorsHaren Gandhi, Jun Li, Ronald Hurley
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Abstract
A catalyst system for use with an internal combustion engine to provide emissions reductions under lean and stoichiometric operating conditions. The catalyst system comprises a first catalyst comprised of a newly developed Perovskite-based formulation having an ABO3 crystal structure designed to bring the precious metal and NOx trapping elements close together. The first catalyst acts primarily to maximize the reduction of emissions under lean operating conditions. The catalyst system also comprises a second catalyst comprised of precious metals which acts primarily to maximize the reduction of emissions under stoichiometric conditions.
Claims20
A method of reducing emissions from an exhaust gas stream comprising:
- providing a first catalyst for optimizing the storage of NOx emissions under lean air/fuel ratios, comprising a Perovskite-type ABO3 crystal structure wherein
- the A cation sites are occupied by lanthanide ions and the B cation sites are occupied by cobalt ions, wherein from about 1 to up to 70% of the lanthanide A cation sites are substituted with a NOx trapping metal selected from the group consisting of barium, magnesium and potassium, wherein from about 1 to up to 60% of the cobalt B cation sites are substituted with a metal selected from the group consisting of platinum, rhodium, iron, copper and manganese;
- and
- providing a second catalyst for optimizing the reduction of hydrocarbon, NOx and CO emissions under stoichiometric air/fuel ratios comprising a catalyst mixture PM-Rh wherein PM is a catalyst material selected from the group consisting of platinum, palladium and combinations thereof wherein the first and second catalysts are closely coupled, the first catalyst being placed in a forward position and the second catalyst being placed in a downstream position in the exhaust stream.
A method of reducing emissions from an exhaust gas stream comprising:
- providing a first catalyst for optimizing the storage of NOx emissions under lean air/fuel ratios, comprising a Perovskite-type ABO3 crystal structure wherein the A cation sites are occupied by lanthanide ions and the B cation sites are occupied by cobalt ions, wherein from about 1 to up to 70% of the lanthanide A cation sites are substituted with a NOx trapping metal selected from the group consisting of barium, magnesium, and potassium, wherein from about 1 to up to 60% of the cobalt B cation sites are substituted with a metal selected from the group consisting of platinum, rhodium, iron, copper and manganese;
- providing a second catalyst for optimizing the reduction of hydrocarbon, NOx and CO emissions under stoichiometric air/fuel ratios, comprising a catalyst mixture PM-Rh where PM is a catalyst material selected from the group consisting of platinum, palladium and combinations thereof;
- and
- placing an exhaust gas sensor between the first and second catalysts.
A method of reducing emissions from an exhaust gas stream comprising:
- providing a first catalyst for optimizing the storage of NOx emissions under lean air/fuel ratios, comprising a Perovskite-type ABO3 crystal structure wherein
- the A cation sites are occupied by lanthanide ions and the B cation sites are occupied by cobalt ions, wherein from about 1 to up to 70% of the lanthanide A cation sites are substituted with a NOx trapping metal selected from the group consisting of barium, magnesium and potassium, wherein from about 1 to up to 60% of the cobalt B cation sites are substituted with a metal selected from the group consisting of platinum, rhodium, iron, copper and manganese;
- providing a second catalyst for optimizing the reduction of hydrocarbon, NOx and CO emissions under stoichiometric air/fuel ratios comprising a catalyst mixture PM-Rh wherein PM is a catalyst material selected from the group consisting of platinum, palladium and combinations thereof wherein the first and second catalysts are closely coupled, the first catalyst being placed in a forward position and the second catalyst being placed in a downstream position in the exhaust stream;
- and
- placing an exhaust gas sensor between the first and second catalysts.
Dependencies are inferred from the claim text.