Shape Forming of Alumina-Silica of High Thermal Stability for Space Propulsion Applications

Abstract

The replacement of toxic hydrazine used for catalytic propulsion by less toxic propellants such as ionic liquids is of hot interest. The challenge for this replacement is the formulation, development and shape forming of new catalysts. Efficient catalysts for the decomposition of aqueous 79 wt.-% HAN solutions (hydroxylammonium nitrate NH3OH+NO3 -) contain 10 wt.-% Pt active phase deposited on a support. Laboratory-made powder catalysts contain platinum supported on Si-doped alumina and display a good activity at low temperature. But, for industrial applications in propulsion thrusters, the pressure drop due to a powder is too high and consequently shape formed supports and catalysts must be prepared and investigated. Two catalyst types have been prepared (i) from shaped supports obtained at the laboratory level using the “oil-drop” method and (ii) from supports formed through an industrial procedure. Both shape formed samples display comparable properties as the powder support, such as high thermal stability linked to the presence q and d aluminas and similar BET surface area. Catalysts based on these supports show efficient catalytic activities.