In the process of recovery and regeneration of cabin atmosphere to supply oxygen to facilitate extended-duration manned missions, including expeditions to Mars or a return to the Moon, one of the byproducts of this reaction is waste methane, which is vented into space. This innovation reclaims hydrogen from the methane using a low-power, non-thermal plasma discharge process based on distributed hollow-cathode and filamentary discharges. This hollow-cathode, non-thermal plasma (HCNTP) is characterized by electrons and heavy particles being in thermodynamic non-equilibrium with electrons heated to 10,000 K and above, while ions and neutral species remain at near ambient temperature. By using pulsed voltage waveforms for generating the plasma discharge, a majority of electric energy goes into heating electrons.

These energetic electrons, along with the resulting radicals and metastable species, produce a chemically reactive gas phase that, when coupled to suitable catalyst materials, is capable of producing a significant amount of molecular hydrogen from a methane/carbon dioxide waste stream. The projected equivalent system mass (ESM) of this system is significantly lower than that of conventional approaches, such as microwave-based systems operating with thermal plasma. The lower ESM of the non-thermal process provides NASA’s life support systems with an alternative approach to closing the mass and energy recycling loops for extended duration manned missions.

The hydrogen recovery system is based on a low-temperature, low-power (20% hydrogen (based on mole %) with minimal soot formation from 25 to 50 mL/min of gas. This enables the reduction of filtration requirements. Alternatively, operating parameters and catalysts can be chosen so as to produce liquid, fuel-grade hydrocarbon products for recovery. Hence, the production and recovery of hydrogen or fuel-grade hydrocarbons from the methane waste stream can reduce hydrogen resupply requirements and can improve the overall efficiency of the Sabatier process.

This work was done by Ordway Boriack and Paul Spence of Lynntech, Inc. for Marshall Space Flight Center. For more information, contact Ronald C. Darty, Licensing Executive in the MSFC Technology Transfer Office, at This email address is being protected from spambots. You need JavaScript enabled to view it.. Refer to MFS-32957-1.


NASA Tech Briefs Magazine

This article first appeared in the October, 2014 issue of NASA Tech Briefs Magazine.

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