Oxygen production from lunar regolith: thermochemical equilibrium, pyrolysis kinetics, and electrochemical pump modeling

The production of oxygen from lunar regolith is essential for sustaining long-term human presence on the Moon. While thermal pyrolysis can effectively release oxygen from the regolith, the resulting gas stream contains impurities that must be removed to obtain high-purity oxygen. This study investigates the use of an electrochemical oxygen pump to concentrate and purify oxygen from the dilute pyrolysis product gas. A two-dimensional multiphysics model was developed in COMSOL to simulate the transport and electrochemical phenomena within the pump. The simulation results demonstrate effective oxygen capture even at low oxygen partial pressures and moderate current densities. At an inlet oxygen partial pressure of 0.04 Pa and an applied current density of 5000 A/m2, the model predicts a capture rate of 42% and a Faradaic efficiency exceeding 98%. Transient analysis reveals that while the capture rate is sensitive to fluctuations in oxygen partial pressure, the cell voltage remains stable under varying conditions. These findings provide valuable guidance for the design and operation of integrated oxygen production systems for future lunar missions.