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

• Published in: Chemical engineering science 2019-04, Vol.198, p.43-51
• Main Authors: Epiepang, Franklin E., Yang, Xiong, Li, Jianbo, Wei, Yuwei, Liu, Yingshu, Yang, Ralph T.
• Format: Article
• Language: English
• Subjects: AgCa-LSX; Air separation; Li-LSX; LiSr-LSX; Mixed-cation zeolites
• ISSN: 0009-2509; 1873-4405
• DOI: 10.1016/j.ces.2018.12.048

•LSX containing minimum Li and Ag were prepared and evaluated for air separation.•ion exchange procedures were designed to miniemize Li+ on inaccessible sites.•The mixed-cation LSX were compared against pure Li-LSX for air separation by PSA.•The mixed cation zeolites show promising performance for replacing Li-LSX. 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.