摘要:
An emission control system is provided. The emission control system includes an oxidation catalyst having a precious metal loading of less than 100 grams (g)/cubic foot (ft3) and a selective catalytic reduction (SCR) component positioned downstream of the oxidation catalyst operated between 150° C. and 300° C. during engine operation to reduce the formation of N2O in the selective-catalytic reduction component.
摘要:
A hydrocarbon and NOx catalyst trap includes a three-way catalyst, and a zeolite layer adjacent to the three-way catalyst and including alumina and silica arranged to form a repeating skeletal frame that defines cavities including active metal active sites for hydrocarbon and NOx trapping such that individual atoms of the active metal are bound to the frame within the cavities via oxygen atoms.
摘要:
A hydrocarbon and NOx catalyst trap includes a three-way catalyst, and a zeolite layer adjacent to the three-way catalyst and including alumina and silica arranged to form a repeating skeletal frame that defines cavities including active metal active sites for hydrocarbon and NOx trapping such that individual atoms of the active metal are bound to the frame within the cavities via oxygen atoms.
摘要:
Methods and systems are provided for reducing engine cold-start emissions. An exhaust system having a passive NOx adsorber (PNA) may store NOx during an engine cold-start until conditions are optimal for release of the stored NOx to a downstream SCR catalyst. Based on PNA conditions, including a NOx load and a PNA bed temperature, adjustments to EGR rate and/or injection timing may be made to achieve a catalytically favorable ratio of NOx species upstream of the SCR catalyst, after the SCR catalyst has reached its light-off temperature.
摘要:
A selective catalytic reduction (SCR) catalyst includes a support layer. A copper-loaded chabazite (Cu/CHA) layer is supported on the support layer. A copper-loaded beta zeolite (Cu/beta) is supported on the Cu/CHA layer. The Cu/beta may be hydrothermally pre-aged prior to use of the SCR catalyst in a vehicle. The pre-aged Cu/beta is essentially free of phosphorous (P), calcium (Ca), zinc (Zn), sodium (Na), potassium (K), magnesium (Mg), iron (Fe), CaSO4, Ca19Zn2(PO4)14, CaZn2(PO4)2, ash, and/or soot.
摘要:
Methods and systems are provided for reducing engine cold-start emissions. An exhaust system having a passive NOx adsorber (PNA) may store NOx during an engine cold-start until conditions are optimal for release of the stored NOx to a downstream SCR catalyst. Based on PNA conditions, including a NOx load and a PNA bed temperature, adjustments to EGR rate and/or injection timing may be made to achieve a catalytically favorable ratio of NOx species upstream of the SCR catalyst, after the SCR catalyst has reached its light-off temperature.