Selection of Ionic Liquids and Characterization of Hypergolicy with Hydrogen Peroxide

Abstract

A theoretical screening and experimental characterization of the hypergolicy of different ionic liquids in combination with highly concentrated hydrogen peroxide was conducted. The aim of the investigation was to find a possible alternative hypergolic bipropellant, which substitutes the commonly used hypergolic propellant combinations of hydrazines and dinitrogen tetraoxide. Highly concentrated hydrogen peroxide was chosen as green oxidizer, ionic liquids were chosen as alternative fuels. Ionic liquids offer very low vapor pressures compared to common fuels and this allows simplified handling procedures. The theoretical screening focused on commercially available ionic liquids. Criteria for the selection of ionic liquids included density, melting point, viscosity and theoretical performance calculations. By means of these results 1-butyl-3-methylimidazolium acetate (BMIM Ac) was chosen for further investigation. Pure BMIM Ac was tested with the so-called drop test method and did not show a hypergolic behavior with hydrogen peroxide. Hence catalytic transition metals like acetate salts were dissolved in the ionic liquid. With different concentrations of copper (II) acetate hypergolic ignition was archived. The ignition delay time is in the order of several 100 milliseconds.