초록 ▼

A catalyst able to overcome defects of an absorption reduction-type NOx purifying catalyst, such as poor NOx purifying capability at low temperatures and low SOx desorbing property, is provided.The catalyst is an absorption reduction-type NOx purifying catalyst where NOx absorbent particles and supp

A catalyst able to overcome defects of an absorption reduction-type NOx purifying catalyst, such as poor NOx purifying capability at low temperatures and low SOx desorbing property, is provided.The catalyst is an absorption reduction-type NOx purifying catalyst where NOx absorbent particles and support particles having supported thereon a catalyst component are mixed. Preferably, acidic support particles are added to the support particle, the NOx absorbent particles are a metal oxide having a base point, and the metal oxide is rare earth-added zirconia. In conventional catalysts, the NOx absorbent such as alkali metal having strong basicity exposes the catalyst component present together on the same support to the basic condition to decrease the catalytic performance. However, in the present invention, the NOx absorbent and the support are separate particles, whereby the catalyst component can exert its original catalytic performance and, as a result, the NOx purifying capability at low temperatures and the SOx desorbing property are improved.

대표청구항 ▼

1. An absorption reduction-type NOx purifying catalyst comprising a NOx absorbent particle, a support particle having supported thereon a catalyst component comprising a noble metal, and an acidic support particle, wherein the catalyst component comprising a noble metal is not supported on the NOx a

1. An absorption reduction-type NOx purifying catalyst comprising a NOx absorbent particle, a support particle having supported thereon a catalyst component comprising a noble metal, and an acidic support particle, wherein the catalyst component comprising a noble metal is not supported on the NOx absorbent particle.2. The absorption reduction-type NOx purifying catalyst as claimed in claim 1, wherein said NOx absorbent particles are a metal oxide having a base point for donating an electron.3. The absorption reduction-type NOx purifying catalyst as claimed in claim 2, wherein said metal oxide is rare earth-added zirconia or alkaline earth-added zirconia.4. The absorption reduction-type NOx purifying catalyst as claimed in claim 1, wherein said NOx absorbent particle is rare earth-added zirconia of formula (1) below:MxZr1-xO(2-x/2)??(1) wherein M is rare earth metal; and x is from 0.01 to 0.70; or alkaline earth-added zirconia of formula (2) below:NxZr1-xO(2-x)??(2) wherein N is alkaline earth metal; and x is from 0.01 to 0.50. 5. The absorption reduction-type NOx purifying catalyst as claimed in claim 4, wherein the support particle comprises alumina, silica, titania, zirconia or ceria.6. The absorption reduction-type NOx purifying catalyst as claimed in claim 5, wherein the support particle comprises γ-alumina.7. The absorption reduction-type NOx purifying catalyst as claimed in claim 1, wherein the acidic support particle comprises WO3/ZrO2, alumina-silica or zeolite.