The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 26, 2005
Filed:
Jan. 14, 2000
Hidehiro Iizuka, Hitachinaka, JP;
Kojiro Okude, Hitachi, JP;
Masato Kaneeda, Hitachi, JP;
Kousei Nagayama, Tokai-mura, JP;
Hisao Yamashita, Hitachi, JP;
Osamu Kuroda, Hitachi, JP;
Yuichi Kitahara, Hitachinaka, JP;
Hidehiro Iizuka, Hitachinaka, JP;
Kojiro Okude, Hitachi, JP;
Masato Kaneeda, Hitachi, JP;
Kousei Nagayama, Tokai-mura, JP;
Hisao Yamashita, Hitachi, JP;
Osamu Kuroda, Hitachi, JP;
Yuichi Kitahara, Hitachinaka, JP;
Hitachi, Ltd., Tokyo, JP;
Abstract
In a method and apparatus for removing nitrogen oxides from the exhaust gas of a lean-burn automobile, a CO adsorbent component, which may, for example be made of Pd, Ru or Ir, is contained in an exhaust gas cleaning catalyst which captures NOx when the air-fuel ratio of exhaust gas is higher than theoretical air-fuel ratio, and reduces the captured NOx when the air-fuel ratio of exhaust gad is less than or equal to the theoretical air-fuel ratio. The catalyst, which includes Rh, Pt, and element selected from among the alkaline and alkaline earth metals (Na, Mg, K, Li, Cs, Sr and Ca), and a CO adsorbent material comprising Pd, Ir or Ru, has a CO desorption capacity that reaches at maximum level at a temperature within the range from 200 to 220° C. when its temperature is increased in a He gas flow at the rate of 5 to 10° C./min, after said catalyst is saturated at 100° C. Exhaust gas having an air-fuel ratio higher than theoretical air-fuel and exhaust gas having an air-fuel ratio less than or equal to the theoretical air-fuel ratio are alternately made to flow to the catalyst.