Decomposition of Monopropellant Blends of Hydroxylammonium Nitrate and Imidazole-Based Ionic Liquid Fuels

Potential dual-mode monopropellant/electrospray-capable mixtures of hydroxylammonium nitrate with ionic liquid fuels [Bmim][] and [Emim][] are synthesized and tested for catalytic decomposition in a microreactor setup. The setup is benchmarked using a 30% hydrogen peroxide solution decomposed via silver catalyst. Results show similar trends but with variance in the quantitative data obtained in the literature. This was found to be a direct result of the sample-holder geometry. Hydrazine decomposition was conducted on an unsupported iridium catalyst. The same trends in terms of pressure-rise rate during decomposition are obtained with unsupported catalyst but at 100 °C instead of room temperature for tests conducted on supported catalysts in the literature. For the [Bmim][]/hydroxylammonium nitrate propellant, rhenium catalyst preheated to 160 °C yielded a pressure-rise rate of , compared to for iridium catalyst and for no catalyst at the same temperature. [Emim][]/hydroxylammonium nitrate propellant shows slightly less activity at 160 °C preheat temperature, yielding a pressure-rise rate of 20, 4, and for injection onto rhenium, iridium, and the thermal plate, respectively. Final results indicate that desirable ignition performance may potentially be obtained by using a supported rhenium catalyst.