Two-Stage Vacuum Pressure Swing Adsorption Using AgLiLSX Zeolite for Producing 99.5+% Oxygen from Air

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• 作者：Daniel Ferreira ; Marta Boaventura ; Patrick Bárcia ; Roger D. Whitley ; Adélio Mendes
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2016
• 出版时间：January 27, 2016
• 年：2016
• 卷：55
• 期：3
• 页码：722-736
• 全文大小：760K
• ISSN：1520-5045

文摘

Oxygen concentrations above 99.5% are required for several applications, mainly in the medical and aerospace fields. Two-stage pressure swing adsorption (PSA) processes, combining kinetic separation with equilibrium separation, have been developed for producing 99+% oxygen from air. Argon and nitrogen are kinetically removed from the air feed using a carbon molecular sieve adsorbent and the remaining nitrogen is removed using a N₂/O₂ selective zeolite. Despite that, two-stage processes are often unattractive, complex, and energy consuming, requiring two or more compressors/vacuum pumps. Moreover, most of the two-stage units described in literature are unable to reach the required oxygen purity of 99.5%. This work studies three energy-efficient two-stage vaccuum PSA (VPSA) processes, combining an equilibrium based PSA (EPSA) or a kinetic based PSA (KPSA) for the first stage, with a VPSA unit packed with the Ar/O₂ selective zeolite AgLiLSX for the second stage, aiming to produce 99.5+% oxygen; the use of zeolite AgLiLSX allows removing argon besides nitrogen. The best two-stage VPSA configuration allowed obtaining a 99.8% oxygen stream at 6% of recovery and a 99.5+% oxygen stream at 14+% of recovery.