Exhaust Gas Purifier

Abstract

It is intend to provide at low cost an exhaust gas purifier capable of in an internal combustion engine or other combustion instrument mainly driven under excess air conditions, efficiently removing nitrogen oxides from exhaust gas. A nitrogen oxide adsorbent (4) is disposed in an exhaust passage, which the nitrogen oxide adsorbent (4) is composed of a lithium composite oxide of the general formula LiAxOy or LiAxPO4, containing as constituent elements lithium (Li) and at least one element (A) selected from the group consisting of manganese (Mn), nickel (Ni), cobalt (Co), vanadium (V), chromium (Cr), iron (Fe), titanium (Ti), scandium (Sc), and yttrium (Y). For example, the nitrogen oxide adsorbent (4) is composed of a lithium composite oxide, such as lithium manganate (LiMnO3), the lithium titanate (Li2TiO3) or lithium manganate phosphate (LiMnPO4).

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application is a divisional application of application Ser. No. 11 / 887,118, filed Sep. 25, 2007, which is a National Phase of International Application No. PCT / JP2006 / 304996, filed Mar. 13, 2006, which claims priority under 35 U.S.C. §119 to Japanese Patent Application No. JP 2005-093798, filed Mar. 29, 2005, and Japanese Patent Application No. JP 2005-093802, filed Mar. 29, 2005, the entire disclosures of which are herein expressly incorporated by reference.TECHNICAL FIELD[0002]The present invention relates to an apparatus for purifying exhaust gas of an internal combustion engine such as a diesel engine, a gas engine, a gasoline engine, and a gas turbine engine or a combustion device such as an incinerator and a boiler. More particularly, the present invention relates to an exhaust gas purifier suitably removes nitrogen oxide while being installed within an exhaust gas passage of the internal combustion engine or the like which is ...

AI Technical Summary

Benefits of technology

[0072]Thus, according to the invention, the lithium composite oxide containing the lithium (Li) utilizes as the positive electrode material for lithium-ion battery and the transition metal such as the manganese (Mn) is used as the nitrogen oxide adsorbent, so that the nitrogen oxide adsorbent having the good NOx absorbing power can be provided at low cost. Therefore, exhaust gas purifier having the large saturated NOx adsorbed amount can be provided at low cost. Particularly, the platinum-added lithium titanate is used as the lithium titanium composite oxide, or the sulfur oxide adsorbent is disposed on the exhaust gas upstream side of the nitrogen oxide adsorbent. Therefore, the poisoning of the nitrogen oxide adsorbent can be prevented.

[0073]The provision of the low-cost nitrogen oxide adsorbent made of the metal oxide containing no noble metal, particularly made of the transition metal oxide can decrease the apparatus cost while easily and efficiently detoxifying and discharging the nitrogen oxide.

Problems solved by technology

However, the apparatus itself is large and extremely expensive, and a maintenance cost of the reducing agent such as ammonia and urea is also increased.

Further, there is a high possibility that the unconsumed ammonia is discharged into atmosphere.

In the nitrogen oxide occluding type catalyst which is commercialized in the small gas engine and automobile gasoline engine, the purifier becomes expensive because the noble metal is always contained as the catalyst component, an operation range (such as temperature and SV value) where the reduction can completely be performed is restricted to a narrow range, and complicated lean and rich control (control of air and fuel supply amounts) is required on an engine side.

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