Catalyst development for microchannel reactors for martian in situ propellant production

Catalytic microchannel reactors were designed for in situ propellant production for Mars exploration. In the reactor system, the Sabatier and the reverse water–gas-shift (RWGS) reactions were carried out for methane and oxygen production using carbon dioxide and hydrogen as feed stock. The focus of the present study was on developing catalysts for these two reactions, aiming at intensifying reactor operation. Demonstrated in this study were the catalyst development pathways and integration methodologies for microchannel reactor system. Initially, near intrinsic kinetic performance was obtained with powder form catalyst. Catalytic performance of the powder form material was therefore used to guide development of structured catalysts which were fabricated on FeCrAlY substrates. In this study, the effects of the noble metals and the properties of their supports on the conversion of CO2 were evaluated. It was found that 3% Ru/TiO2 (R/A = 60:40) and 6%Ru/CeO2-ZrO2 were very active Sabatier and RWGS catalysts allowing to achieve near equilibrium conversion at high throughputs. In the stability testing under repeated start-up and shut-down cycles, both the Sabatier and the RWGS catalysts were stable, retaining initial activities for sustained period of time.