A life support system generates oxygen in low oxygen and/or hazardous environments such as mining, chemical/biological attacks, nuclear fallout, or space exploration. Based on proven technology, this O2/CO2 control system has the potential to significantly reduce the mass of the oxygen carried into the low oxygen and/or hazardous environment by continuously regenerating the oxygen used by the human subject(s).

The design incorporates three key components: (1) a carbon dioxide adsorbent bed to remove CO2 from human exhaled breath, (2) a catalytic carbon deposition layer (CCDL) to promote carbon deposition from CO2, and (3) a ceramic oxygen generator (COG) to separate and pump pure oxygen away from decomposed CO2. The CCDL employs high-surface-area transition metal/transition metal oxide catalysts to promote carbon separation and deposition from CO2. The carbon, deposited on the removable CCDL, can then be discarded or reused for another process. As the system approaches 100% efficiency, few additional oxygen sources (such as oxygen tanks) would be necessary, as most of the exhaled carbon dioxide would be converted to oxygen for continuous life support.

To decrease the requirement for heavy insulation, a novel ceria-bismuth oxide bilayer electrolyte is employed, which was previously developed for NASA’s Mars mission in situ resource utilization (ISRU). The bilayer electrolyte was shown to allow a reduction in operating temperature to ≈500 to 600 °C, which significantly reduces insulation mass and thermal energy input, thereby allowing for greater portability. Recent improvements in processing techniques, and further research, have enabled the fabrication of thin bilayers and new, higher-performance electrodes.

The efficacy of the advanced life support system depends much on the ability of the sorbent bed to remove CO2 from the exhaled breath. To that end, polyethyleneimine (PEI)-modified mesoporous molecular sieve MCM-41 has been used.

This work was done by Eric D. Wachsman, Keith L. Duncan, and Helena H. Weaver of the University of Florida for Johnson Space Center. For further information, contact the Johnson Technology Transfer Office at (281) 483-3809. MSC-24487-1

NASA Tech Briefs Magazine

This article first appeared in the February, 2015 issue of NASA Tech Briefs Magazine.

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