| abstract |
(a) a zeolite material having an average crystal size of at least about 0.5 탆 and a CHA framework structure containing silicon and aluminum and a silica to alumina mole ratio (SAR) of about 10 to about 25; And (b) an optional framework promoter metal (M) disposed in the zeolite material as free metal and / or exchanged metal, wherein the optional framework promoter metal is copper, iron and mixtures thereof, (M) aluminum atomic ratio (M: Al) of from about 0.10 to about 0.24, based on the structural aluminum, and optionally (c) at least about 1 wt% of cerium to the zeolite material, based on the total weight of the zeolite Wherein the cerium is present in a form selected from exchanged cerium ions, monomer ceria, oligomer ceria and combinations thereof, provided that the oligomer ceria has a particle size of less than 5 탆. |