Zirconia and sulfate in NOx traps to improved trapping and sulfur tolerance

The invention is a nitrogen oxide trap comprising a porous support loaded with 6-15 wt. % strontium oxide and thereon, a mixture of: 0.5-5 wt. % precious metal catalyst selected from platinum, palladium, rhodium or mixtures thereof loaded, 3.5-15 wt. % zirconium and 15-30 wt. % sulfate, where prefer...

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Bibliographische Detailangaben
Hauptverfasser:	DOBSON, DOUGLAS A, WATKINS, WILLIAM LEWIS HENDERSON, HUBBARD, CAROLYN PARKS
Format:	Patent
Sprache:	eng
Schlagworte:	CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOIDCHEMISTRY CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TOTRANSPORTATION GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS PERFORMING OPERATIONS PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL SEPARATION TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINSTCLIMATE CHANGE THEIR RELEVANT APPARATUS TRANSPORTING
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Beschreibung
Zusammenfassung:	The invention is a nitrogen oxide trap comprising a porous support loaded with 6-15 wt. % strontium oxide and thereon, a mixture of: 0.5-5 wt. % precious metal catalyst selected from platinum, palladium, rhodium or mixtures thereof loaded, 3.5-15 wt. % zirconium and 15-30 wt. % sulfate, where preferably the ratio of zirconium to sulfate ranges from about 1:1 to 1:7; each wt. % being individually based on the weight of the support. The trap may be used in an internal combustion engine exhaust gas catalyst system. During lean-burn operation of the engine the trap sorbs nitrogen oxides (NOx) and releases the nitrogen oxides during decreased oxygen concentration in the exhaust gas, the desorbed NOx being converted to N2 and O2.