Sorbent Structural Testing for Advanced Exploration Systems

Long term space missions require carbon dioxide removal systems that can function with minimal downtime required for maintenance, low power consumption and maximum efficiency for CO2 removal. A major component of such a robust system are the sorbents used for the CO2 and desiccant beds. Sorbents must not only have adequate CO2 and H2O removal properties, but they must have the mechanical strength to prevent structural breakdown due to pressure and temperature changes during operation and regeneration, as well as resistance to breakdown due to moisture in the system from cabin air. As part of the studies used to select future CO2 sorbent materials, mechanical tests are performed on various zeolite and silica gel sorbents to determine mechanical performance while dry and at various humidified states. Tests include single pellet crush, bulk crush and attrition tests. In previous years, we have established a protocol for testing sorbents under dry and humid conditions, and tested the sorbents used on the International Space Station carbon dioxide removal assembly.  This paper reports on the testing of a series of commercial sorbents that are candidates for use on future exploration missions.