CATALYST FOR CLEANING EXHAUST GAS FROM INTERNAL-COMBUSTION ENGINE, METHOD FOR MANUFACTURING THE CATALYST, AND EXHAUST GAS-CLEANING APPARATUS

摘要

PROBLEM TO BE SOLVED: To provide a catalyst for cleaning exhaust gas from an internal-combustion engine, which contains a noble metal as a catalytically active component and in which the usage of the noble metal is reduced.

SOLUTION: This catalyst for cleaning exhaust gas has a porous-carrier layer on the surface of a base material and the catalytically active component on the surface of a carrier. A noble metal particle is deposited only on the surface or its vicinity of the carrier layer where exhaust gas is circulated. A noble metal-suspended solution is prepared by a method for destroying an ion balance of a noble metal ion-containing solution, the carrier layer formed on the monolithic honeycomb base material is impregnated with the prepared noble metal-suspended solution and the noble metal particle-deposited base material is fired so that the noble metal particle can be deposited on the surface of the carrier layer while being distributed unevenly. The usage of the noble metal can be made lower in comparison with such a case that the noble metal is deposited on the whole surface of the carrier having pores.

COPYRIGHT: (C)2006,JPO&NCIPI