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Incineration is a promising method for converting biomass and human waste into CO2 and H2O during extended planetary exploration. During incineration, small amounts NOX and SO2 are produced and must be removed. TDA has developed a NOX control process that is safe and effective and does not require addition of NH3, which is commonly used in selective catalytic reduction of NOx. In our process, NO is catalytically oxidized to NO2 which is then removed by wet scrubbing with a weak base to form an innocuous water solution of nitrates and nitrites. We plan to integrate our catalytic NO oxidation process into a complete gas cleaning system that will remove NOX, SO2, particulate material, CO and unburned organic compounds.

The control of trace contaminants on the International Space Station (ISS) is carried out by a combination of activated carbon absorption and catalytic oxidation. The carbon bed absorbs most hydrocarbons, chloro and chlorofluorocarbons (CHCs and CFCs) while the catalytic oxidizer removes compounds such as methane, ethylene, ethane, and carbon monoxide that cannot be absorbed by the charcoal bed. Unfortunately, the Space Station catalyst of 0.5% palladium on alumina does not effectively oxidize CHCs and CFCs, and in fact is powerfully poisoned by them (Wright et al. 1996). Thus, even though the charcoal bed has little affinity for CFCs and CHCs, it must be sized to completely remove these compounds in order to protect the crew and prevent poisoning of the catalytic oxidizer. TDA Research Inc. (TDA), under contract to NASA-JSC, has designed, built, and tested an all-catalytic trace contaminant control system (TCCS) to be used in Phase III of the Early Human Testing Program.