Design and use of a batch reactor for catalytic decomposition of different monopropellants

Abstract

The use of pure hydrazine as monopropellant for small thrusters suffers some disadvantage due to the toxicity of this molecule associated with its rather high vapor pressure at room temperature. With the aim to replace hydrazine by less toxic but just as efficient propellant, we have developed a constant volume computerized batch reactor which permit to study different monopropellants and their associated catalysts. This reactor can be used as a screening reactor and its main advantages are: easy use, fast change of catalyst or propellant, very limited consumption of propellant or catalyst, simultaneous recording of reactor pressure, catalyst and gas phase temperatures. The catalyst can be preheated and the working pressure is between vacuum and 2 bars. The main parameters that can be obtained are the efficiency and the rate of the catalytic decomposition as well as the ignition delay and the onset temperature. Three propellants have been checked: pure hydrazine, hydrogen peroxide and a HAN-TEAN-water mixture; they display similar rates and ignition delays but the HAN-based propellant needs higher initial temperature and leads to the parallel formation of solid products. For a specific propellant, this reactor permits to classify different catalytic beds before further investigations.