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In the Sabatier reactor, oxygen is recovered (as water) by hydrogenation of carbon dioxide. One half of the reacted hydrogen is contained within the product water, the other half is used to form methane (CH4). Hydrogen resupply requirements for the oxygen recovery process can be minimized by reclamation of hydrogen from the methane waste. To this end, we have developed effective methods for the recovery of hydrogen from CH4 using a microwave plasma reactor. By selectively promoting the oligomerization reaction which forms hydrogen and acetylene, up to 75% of the waste hydrogen can be recovered in a manner which minimizes the carbon fouling and carbon build-up problems which drastically reduce the long-term viability of traditional methane pyrolysis methods using fixed bed and fluidized bed reactors.

Gradient magnetically assisted fluidized bed (G-MAFB) methods are under development for the decomposition of solid waste materials in microgravity and hypogravity environments. The G-MAFB has been demonstrated in both laboratory and microgravity flight experiments. In this paper we summarize the results of gasification reactions conducted under a variety of conditions, including: combustion, pyrolysis (thermal decomposition), and steam reforming with and without oxygen addition. Wheat straw, representing a typical inedible plant biomass fraction, was chosen for this study because it is significantly more difficult to gasify than many other typical forms of solid waste such as food scraps, feces, and paper. In these experiments, major gasification products were quantified, including: ash, char, tar, carbon monoxide, carbon dioxide, methane, oxygen, and hydrogen.

In the Sabatier reactor, oxygen is recovered (as water) by hydrogenation of carbon dioxide. Half of the reacted hydrogen is contained within the product water, the other half forms methane (CH4). To close the hydrogen loop, we are investigating methods for the efficient recovery of hydrogen from CH4. This paper describes microwave plasma-based methods for the thermal decomposition (cracking) of methane to produce hydrogen, elemental carbon, and related carbonaceous substances. Two primary reactor configurations have been employed in this work: 1) a quartz tube vertically oriented within a section of rectangular waveguide, and 2) waveguide transmission through a quartz window into a cylindrical vacuum chamber based multimode cavity. Hydrogen recoveries of up to 98% have been obtained. Three primary mechanisms of methane decomposition have been identified: methane pyrolysis, methane oligomerization, and methane aromatization.