Use of a palladium/platinum/zeolite-based catalyst as passive nitrogen oxide adsorber for purifying exhaust gas
AssigneeUmicore AG & Co. KG
InventorsChristoph Hengst, Michael Lennartz, Frank-Walter Schuetze
Life of this patent
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Abstract
The invention relates to the use of a catalyst as a passive nitrogen oxide adsorber, which has a carrier substrate, a zeolite, palladium, and platinum, wherein the palladium is provided in a quantity of 0.01 to 10 wt. %, based on the sum of the weights of zeolite, platinum, and palladium and calculated as a palladium metal, and platinum in a quantity of 0.1 to 10 wt. %, based on the weight of the palladium and calculated as a platinum metal. The invention also relates to the use of said catalyst in connection with a SCR catalyst in an exhaust gas system.
Claims23
A catalyst comprising a carrier substrate of length L and a coating A comprising a zeolite, palladium and platinum, wherein palladium is present in amounts of 0.01 to 10 wt. %, based on the sum of the weights of zeolite, platinum and palladium, and is calculated as palladium metal, and platinum is present in amounts of 0.1 to 10 wt. %, based on the weight of palladium, and is calculated as platinum metal, as a passive nitrogen oxide adsorber that stores nitrogen oxides in a first temperature range and releases them again in a second temperature range, wherein the second temperature range is at higher temperatures than the first temperature range, and wherein the largest channels of the zeolite are formed by 6 tetrahedrally coordinated atoms and the zeolite belongs to structure types AFG, AST, DOH, FAR, FRA, GIU, LIO, LOS, MAR, MEP, MSO, MTN, NON, RUT, SGT, SOD, SVV, TOL or UOZ.
A catalyst comprising a carrier substrate of length L and a coating A comprising a zeolite, palladium and platinum, wherein palladium is present in amounts of 0.01 to 10 wt. %, based on the sum of the weights of zeolite, platinum and palladium, and is calculated as palladium metal, and platinum is present in amounts of 0.1 to 10 wt. %, based on the weight of palladium, and is calculated as platinum metal, as a passive nitrogen oxide adsorber that stores nitrogen oxides in a first temperature range and releases them again in a second temperature range, wherein the second temperature range is at higher temperatures than the first temperature range, and wherein the largest channels of the zeolite are formed by 9 tetrahedrally coordinated atoms and the zeolite belongs to structure types -CHI, LOV, NAB, NAT, RSN, STT or VSV.
A catalyst comprising a carrier substrate of length L and a coating A comprising a zeolite, palladium and platinum, wherein palladium is present in amounts of 0.01 to 10 wt. %, based on the sum of the weights of zeolite, platinum and palladium, and is calculated as palladium metal, and platinum is present in amounts of 0.1 to 10 wt. %, based on the weight of palladium, and is calculated as platinum metal, as a passive nitrogen oxide adsorber that stores nitrogen oxides in a first temperature range and releases them again in a second temperature range, wherein the second temperature range is at higher temperatures than the first temperature range, and wherein the largest channels of the zeolite are formed by 10 tetrahedrally coordinated atoms and the zeolite belongs to structure types FER, MEL, MFI, MTT, MWW or SZR, and wherein the coating A is free of a combination of LTL type zeolite with either platinum, palladium or platinum and palladium.
Dependencies are inferred from the claim text.