Chemical kinetics interpretation of hypergolicity of dicyanamide ionic liquid-based systems

Ionic liquids are candidates for replacing hydrazine and hydrazine derivatives systems. A detailed chemical kinetics model has been built to examine the gas-phase chemistry between isocyanic acid (HNCO), white fuming nitric acid (WFNA), N2O, CO2, and water, especially at low temperatures (ambient to 423 K). This kinetics model is able to explain the gas-phase ignition observed during hypergolic ignition of the ionic liquid 1-butyl-3-methyl-imidazolium dicyanamide (BMIM-dca) with WFNA. Sensitivity analyses have been performed to examine the reaction pathways for ignition. Ignition is predicted to occur via an exothermic reaction between isocyanic acid (HNCO) and nitric acid (HONO2), and subsequent HONO2 thermal decomposition that has NO2 and OH radicals as the primary chain carriers. A detailed understanding of the initiation processes in the liquid phase is needed, as the BMIM-dca and WFNA begin to react to produce the above preignition species for the proposed chemical kinetics model to describe the ignition behavior of the system. (C) 2011 The Combustion Institute. Published by Elsevier Inc. All rights reserved.