Methane is formed as a product of air revitalisation onboard spacecraft (Sabatier reactor) and also within the MicroEcological Life Support System Alternative (MELiSSA). By its nature, the methane molecule represents a mass in carbon and hydrogen. As these two elements are core elements of organic chemistry, they deserve to be seriously studied for the closure of life support system cycles. Unfortunately, today methane is known to be an end-product of the said recycling processes. Many investigations have considered using methane for electricity production or propulsion, but these processes are so far of poor efficiency and require a high level of purity. It is therefore important to also review and study new processes for an efficient stoichiometric transformation of methane to useful products, and to demonstrate its feasibility at a conceptual level. This is the objective of this activity.

A feasibility testing of the methane pyrolysis technology based on carbon catalyst was performed. Its goals were to demonstrate the feasibility of the process in a reactor scaled to a 6 person crew (reaction volume of 2 l) and assess the efficiency, energy consumption, process kinetics, optimal reaction conditions and sooting / wear of the equipment. A test reactor was built to conduct the feasibility tests.

The product carbon is forming inside the reaction zone and is removed by drilling small holes with the help of a rotating assembly containing motors and drillbits. A Venturi tube is placed in the middle of the top section to create a low pressure zone by movement of gas through a narrow part of the tube. By running gas (methane) at higher speeds periodically through the tube, one can remove the powdered carbon product from the reactor without the need for complicated moving parts. The carbon collects in the bowl-shaped chamber below (by means of drillbit rotation and vertical movement, independent on gravity) and is periodically removed by creating underpressure in the Venturi tube. The total weight of the concept reactor is 23,7 kg excluding the insulation and electronics, and volume is about 17,4 liters.

The following points have been identified to require further work:

• Improve the control over the methane pyrolysis process by adjusting temperature, pressure, reaction time, carbon catalyst type etc. to improve the conversion and products quality
• Find a good strategy for carbon catalyst regeneration
• Assess formation and handling of impurities and by-products
• Develop a system to separate hydrogen from unreacted methane
• Assess the collection and usage of the carbon produced in the pyrolysis unit