Evaluation of hydroxylammonium nitrate (HAN) decomposition using bifunctional catalyst for thruster application

Abstract

Monopropellant thruster technology is at the cusp of revival with new age ionic liquids which are safe, less toxic and high performing emerging as substitutes for traditionally used hydrazine. One such promising candidate is Hydroxylammonium nitrate (HAN). Current study explores an iridium metal impregnated bifunctional variant of an earlier developed doped cerium oxide catalyst for HAN decomposition. The performance of bifunctional catalyst was compared against unsupported cerium oxide catalyst and conventional iridium over gamma alumina catalyst. Thermal analysis was the primary test used for performance evaluation and was subsequently followed up in a batch reactor to evaluate the durability of the catalyst to extreme high temperature exposure. Characterization of catalyst before and after decomposition reaction was comprehensively conducted using surface area analysis, SEM/EDS, XRD and XPS. Results did suggest promotional effect of iridium over doped ceria support as demonstrated through increased pressure build-up and rate of pressure-rise.