The invention relates to faujasite-containing compositions in which the original hydrogen or monovalent forms are ion exchanged to their polyvalent form and then thermally activated to promote dehydration and dehydroxylation of the faujasite while maintaining substantially the same zeolite content. The resulting compositions containing faujasites substantially in their dehydrated/dehydroxylated state have been found to have surprisingly high selectivities and capacities for the separation of air into nitrogen and oxygen.