Compositionally complex catalytic oxide beds free of noble metals for H2O2 fuelled monopropellant thrusters

The primary aim of this study was to go beyond commercially available inert pellets doped with rare and expensive precious metals and tailor green, sustainable and cheap new candidates for the HO decomposition in monopropellant hybrid thrusters. Attention was dedicated to the fastest decomposition response that represents a fundamental requirement for short-time manoeuvres. A set of compositionally complex (CC) oxides, free of noble metals but catalytically active, has been developed. Four different CC formulations were developed and tested: the fastest responsive candidate toward HO decomposition was thus selected, and a batch of solid pellets manufactured. Then, its performance was studied and compared using a commercial Pd/AlO catalyst used as benchmark: comparatively excellent results in terms of both minimal lag time and decomposition efficiency were achieved. Finally, the principal propulsive parameters of the designed configuration, evaluated as gas generator for monopropellant thruster, showed a promising potential as an engine.