Catalytic ignition of ionic liquids for propellant applications

Department of Chemistry and Center for Green Manufacturing, The University of Alabama, Tuscaloosa, AL 35487, USA.
Chemical Communications (Impact Factor: 6.83). 10/2010; 46(47):8965-7. DOI: 10.1039/c0cc02162h
Source: PubMed


In this proof of concept study, the ionic liquids, 2-hydroxyethylhydrazinium nitrate and 2-hydroxyethylhydrazinium dinitrate, ignited on contact with preheated Shell 405 (iridium supported on alumina) catalyst and energetically decomposed with no additional ignition source, suggesting a possible route to hydrazine replacements.

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    • "The use of 2-hydroxyethylhydrazinium nitrate (HEHN) was proposed recently as hydrazine substitute (Shamshina et al., 2010). HEHN is more stable than HAN and displays a glass transition temperature of -57 °C. "

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    ABSTRACT: 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. 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 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 1-butyl-3- methyl-imidazolium dicyanamide and WFNA begin to react to produce the above pre-ignition species for the proposed chemical kinetics model to describe the ignition behavior of the system.
    Full-text · Article · Mar 2011 · Combustion and Flame
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    ABSTRACT: We present studies of molecular dynamics and interactions in azolium azolate energetic ionic liquids (ILs) by utilizing a variety of physical methods. We observe peculiar rheological behavior for these ILs, which deviates from the one expected for molecular glass-formers. Major peculiarities include high elasticity in the low-frequency zone, peculiar van Gurp plots, and failure of time temperature superposition. We attribute these peculiarities to specific interactions in the nitrogen-rich planar rings of azolate ILs. X-ray scattering measurements reveal a “nanometer” ordered organization in azolium azolates. High values of Kamlet–Taft polarity parameters indicate high probability and strength of hydrogen bond interactions in azolate ILs. This conclusion is also supported by ab initio calculations. Our next effort is to break/enhance existing interactions in nitrogen-rich ILs by adding a “H-acceptor”. This will allow better understanding of the nature of interactions in azolium azolates and eventually their control.
    No preview · Article · Sep 2011 · Journal of Physical Chemistry Letters
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