Performance Evaluation of Ru-Pt Alloy Nanoparticles Catalyst for Hydroxylammonium nitrate (HAN) Based Propellant

Abstract

Hydroxylammonium nitrate (HAN) based propellants represent the next generation monopropellants for the rocket launch vehicles. Ruthenium is a promising catalytic material for HAN based propellant, with the merit of high activity and relatively low price. However, ruthenium catalyst is unstable and prone to aggregation and oxidation. Herein, we prepared a Ru-Pt alloy nanoparticles (NPs) catalyst via impregnation method. The addition of Pt effectively delayed the deactivation of Ru. In order to understand the active components of the catalyst, both fresh and aged catalyst samples were characterized. The active species is identified as Ru0 species, which gradually oxidized to Ru/RuOx. In the droplet test and thruster test, Ru-Pt alloy NPs catalyst exhibited higher activity and stability compared to the Ru NPs catalyst and successfully passed through the pulse and 100-seconds long steady-state thruster tests, with good pulse consistency and low steady-state roughness. This work provides a promising pathway to explore low-cost catalysts for HAN decomposition.