Silica-alumina zeolite adsorbents for oxygen generation via pressure swing adsorption: Mechanisms and challenge.

[Display omitted] • Development of oxygen generation from air over zeolite by PSA was reviewed in this work. • Mechanisms of O 2 separation from N 2 over zeolite by adsorption were discussed. • Requirements for zeolite adsorbents to improve the O 2 purity were analyzed. • Effect of impurities in air on the nitrogen–oxygen separation was concluded. The adsorptive generation of oxygen from air has become increasingly important in the chemical and medical industries due to the growing demand for O 2 with high purity. Among the commonly used three methods of cryogenic distillation, pressure swing adsorption (PSA) and membrane separation for N 2 /O 2 separation, PSA has received much attention due to the advantages of small volume, low management cost, and short start-up time, etc. Zeolites, with their unique pore structure, highly polarized pore environment, and abundant ion exchange sites, are widely employed as an efficient adsorbent in N 2 /O 2 separation. Hence, in this work, a review about the application of zeolites in O 2 generation via PSA was performed. In detail, the common PSA techniques applied for O 2 generation were summarized and compared from both the characteristics and application scenarios firstly. Then, the main mechanisms of O 2 separated from N 2 in air over zeolite by adsorption were summarized from three aspects of the steric effect, kinetic effect and equilibrium effect. Based on above, the requirements for silica-alumina zeolite adsorbents to improve the O 2 purity clarified from skeleton topology, extra-framework cations as well as physical & chemical properties. Moreover, the operation conditions and impurities having a significant effect on the product O 2 quality were discussed. Finally, both the challenges and prospects of air separation and O 2 generation are proposed based on existing research results. [ABSTRACT FROM AUTHOR]