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.
