(554e) Two-Stage PSA System for CO2 Removal during Closed-Loop Human Space Exploration Missions

The development of a novel two-stage PSA system is underway that can be used for enriching and recovering CO₂ from a spacecraft cabin that is suitable for use in a Sabatier reactor. This two-stage pressure swing adsorption (PSA) process utilizes Stage 1 to concentrate metabolic CO₂ from about 2667 ppm (0.2667 vol%) to about 600,000 ppm (60 vol%) and Stage 2 to further enrich the CO₂ product from Stage 1 up to > 97 vol% CO₂, while recovering at least 95% of it, which corresponds to removing 4.0 kg/day of CO₂. Each stage of this PSA system utilizes a combination of equalization, cocurrent depressurization and heavy reflux cycle steps to facilitate heavy component enrichment and recovery. The first generation of this two-stage PSA process utilizes beaded commercial adsorbent, i.e., 13X zeolite, in both stages. Implications from these results potentially reach far beyond the needs of NASA and begin to hint at the extreme concentration of CO₂ from ambient air at relatively high recovery or the extreme concentration of any dilute species from a light gas stream using a simple PSA cycle. This presentation will discuss the most recent modeling and/or experimental results.