Air separation sorbents: Mixed-cation zeolites with minimum lithium and silver

Mixed-cation LiSr-LSX, AgCa-LSX and AgSr-LSX containing minimum lithium and silver were prepared by exchanging small fractions of Li⁺ into Sr-LSX and Ag⁺ into Sr-LSX and Ca-LSX. To avoid diffusion of the Li⁺ into the inaccessible sites, the LiSr-LSX sample was exposed to a specifically derived dehydration condition. Similarly, the mixed-silver cation samples were treated to the selected condition post-ion-exchange to allow the Ag⁺ to migrate into SII*. Strong evidences were provided that significant fractions of the exchanged Li⁺ and Ag⁺ remained in SIII and SII* respectively after comparisons of the N₂/O₂ adsorption isotherms and isosteric heats of adsorption of the mixed-cation and single-cation samples. Furthermore, the mixed-cation LiSr-LSX, AgCa-LSX and AgSr-LSX samples were compared against the single-cation Li-LSX sample based on their O₂ productivity performance via a PSA simulation model.