A small pore size synthetic zeolite having a degree of crystallinity of at least 80% and comprising at least 0.01 wt % based on the weight of the zeolite of at least one catalytic metal selected from the group consisting of Ru, Rh, Pd, Ag, Os, Ir, Pt, Au, Mo, W, Re, Co, Ni, Zn, Cr, Mn, Ce, Ga and combinations thereof, wherein at least 80% of the catalytic metal is encapsulated in the zeolite, wherein if the zeolite is an aluminosilicate it has a SiO.sub.2:Al.sub.2O.sub.3 molar ratio of greater than 6:1.

The present disclosure generally provides catalysts, catalyst articles and catalyst systems including such catalyst articles. In particular, the catalyst composition includes a metal ion-exchanged molecular sieve ion-exchanged with at least one additional metal, which reduces the number of metal centers often present in metal promoted zeolite catalysts. Methods of making and using the catalyst composition are also provided, as well as emission treatment systems including a catalyst article coated with the catalyst composition. The catalyst article present in such emission treatment systems is useful to catalyze the reduction of nitrogen oxides in gas exhaust in the presence of a reductant while minimizing the amount of dinitrogen oxide emission.