An NO.sub.x storage member including at least one member selected from the
group consisting of alkali metals, alkaline-earth metals and rare-earth
elements, and at least one noble metal selected from the group consisting
of Pt, Pd and Rh are loaded on a support including a porous oxide
including TiO.sub.2 at least and ZrO.sub.2 on which Rh is loaded in
advance.
H.sub.2, which is generated by Rh/ZrO.sub.2, inhibits the sulfur poisoning,
and the support, which includes TiO.sub.2 at least, secures the initial
NO.sub.x purifying capability, thereby further inhibiting the sulfur
poisoning. Accordingly, it is possible to inhibit the NO.sub.x storage
member from the sulfur poisoning, and to maintain a high NO.sub.x
conversion even after a durability test.
