Development of a Test for Evaluation of the Hydrothermal Stability of Sorbents used in Closed-Loop CO2 Removal Systems



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45th International Conference on Environmental Systems


The International Space Station Carbon Dioxide Removal Assembly uses zeolite 5A molecular sieve material packed into beds for the capture of cabin CO2. The beds are cyclically heated to drive off the CO2 and restore the removal capacity. Over time, the sorbent material has been found to break down resulting in dust that restricts flow through the beds. Humidity adsorbed in the 5A zeolite when it is heated is a suspected cause of this sorbent degradation. To evaluate the impact of adsorbed water during thermal cycling, the Hydrothermal Stability Test was developed. The test configuration provides comparative side-by-side flow restriction data for two sorbent materials at specifically controlled humidity levels. While the initial focus of the testing is on 5A zeolite materials currently used on the ISS, the system will also be used to evaluate future candidate materials. This paper describes the approach, the test system, current results, and future testing.


Bellevue, Washington
James C. Knox, NASA Marshall Space Flight Center, USA
Hernando Gauto, NASA Marshall Space Flight Center, USA
Lee A. Miller, Jacobs ESSA Group, USA
The 45th International Conference on Environmental Systems was held in Bellevue, Washington, USA on 12 July 2015 through 16 July 2015.