Platinum/Barium Hexaaluminate Catalyst to Small-Scale Hydroxylamine Nitrate Thrusters Application

Abstract

M OSTmonopropellant systems use hydrazine as the propellant. Hydrazine is, however, a very strong carcinogen and also flammable [1]. Considering current environmental concerns, studies have been conducted to discover an alternative propellant. Among potential green propellants, the blend of hydroxylamine nitrate (HAN) propellants and fuel has the advantages of higher specific impulse and higher density than hydrazine, and it is also environmentally friendly [2–5]. It is important to maintain a relatively large specific surface area of a catalyst support at high temperatures. This is because HAN-based propellants have very high adiabatic decomposition temperatures [2]. However, gamma alumina-based catalysts have been reported to suffer from sintering and deactivation at high temperatures, such as the decomposition temperatures of HAN-based propellants [6]. A barium hexaaluminate (BHA) catalyst support exhibits excellent thermal stability in high-temperature application, such as methane combustion [7]. The performance of BHA, which has better thermal stability than the conventional gamma alumina support, when using platinum as the active material was tested on a small-scale HAN thruster. The performance was compared with that of alpha alumina, which was used as a control.