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NO.sub.x catalyst and method of suppressing sulfate formation in an exhaust purification system

Patent ·
OSTI ID:1175883
The activity and durability of a zeolite lean-bum NOx catalyst can be increased by loading metal cations on the outer surface of the zeolite. However, the metal loadings can also oxidize sulfur dioxide to cause sulfate formation in the exhaust. The present invention is a method of suppressing sulfate formation in an exhaust purification system including a NO.sub.x catalyst. The NO.sub.x catalyst includes a zeolite loaded with at least one metal. The metal is selected from among an alkali metal, an alkaline earth metal, a lanthanide metal, a noble metal, and a transition metal. In order to suppress sulfate formation, at least a portion of the loaded metal is complexed with at least one of sulfate, phosphate, and carbonate.
Research Organization:
Caterpillar Inc., Peoria, IL (United States)
Sponsoring Organization:
USDOE
DOE Contract Number:
FC05-97OR22579
Assignee:
Caterpillar Inc. (Peoria, IL)
Patent Number(s):
7,094,722
Application Number:
10/327,636
OSTI ID:
1175883
Country of Publication:
United States
Language:
English