Hydrogen reduction of ilmenite: Towards an in situ resource utilization demonstration on the surface of the Moon

Abstract

Water is one of the most vital resources required for future space exploration. By obtaining water from lunar regolith, humans are one step closer to being independent of Earth's resources enabling longer term exploration missions. Hydrogen reduction of ilmenite(FeTiO3) is often proposed as a technique for producing water on the Moon. ProSPA, a miniature analytical laboratory, will perform reduction of lunar soils as an In-Situ Resource Utilization (ISRU) demonstration on the lunar surface. The technique used by ProSPA will be useful for prospecting payloads with limited mass and power resources. This work considers the development and optimization of an ilmenite reduction procedure for use with the ProSPA instrument. It is shown that the reaction can be performed in a static (non-flowing) system, by utilizing a cold finger to collect the water produced from the reaction. Among the investigated parameters an initial H2:FeTiO3 ratio of 1, in this case equating to a hydrogen pressure of 418 mbar, proved to be best for providing maximum yields over 4 h when operating at 1000 °C. Results indicate that a maximum yield of 3.40 ± 0.17 wt % O2 can be obtained at 1000 °C (with a maximum possible yield of 10.5 wt % O2). When operating at higher temperatures of 1100 °C the ilmenite grains undergo a subsolidus reaction resulting in the formation of ferropseudobrookite and higher yields of 4.42 ± 0.18 wt % O2 can be obtained.