Evaluation of Ir/Al2O3, Ir–Ru/Al2O3 and Ru/Al2O3 catalyst performance in a 5 N satellite thruster

Ir/Al2O3, Ir–Ru/Al2O3 and Ru/Al2O3 catalysts with approximately 33% metallic content in mass were prepared in 20 impregnation steps. For the Ru catalyst, two impregnation methods were employed: incipient wetness (chlorinated precursor) and by excess volume (non-chlorinated precursor). For the remaining catalysts, only incipient wetness impregnation was used with chlorinated precursors. Catalyst textural properties were evaluated before and after catalytic tests: metallic grade, specific area, mesopore volume distribution, metallic dispersion, and metallic particle average diameter. Catalysts were tested for hydrazine (N2H4) decomposition reaction in a 5 N satellite thruster and their performances were compared to Shell 405 commercial catalyst. Results showed that catalysts containing Ir were similar in performance to Shell 405 commercial catalyst and that the catalyst containing only Ru should not be used in cold starts.

► Shell 405 reached higher temperatures with a shorter ignition delay time.
► Catalysts containing Ir were similar in performance to Shell 405.
► Catalysts containing only Ru produced much lower chamber temperatures.
► Catalyst containing only Ru should not be used in cold starts.
► Ir–Ru/C can substitute Shell 405 in missions involving 1 long duration hot firing.