HAN and ADN as liquid ionic monopropellants: Thermal and catalytic decomposition processes

Binary HAN and ADN aqueous solutions have been synthesized, then thermally and catalytically decomposed. Binary HAN mixtures were prepared with different concentrations: 95, 80 and 60 wt.%. Whereas ADN solution contains are: 75, 60 and 50 wt.%. The candidate catalysts were prepared by impregnation of alumina doped by lanthanum oxide with active phase precursors: iridium for HAN and copper oxide for ADN and characterized by transmission electron microscopy, X-ray diffraction and chemisorption. The decomposition processes were followed by thermal analysis and a constant batch reactor. This work shows the essential effect of monopropellant concentrations to determine the best green propellants for industrial applications as reaction control systems. Moreover, HAN and ADN solutions are more efficient for catalytic decomposition due to the absence of stabilizer to inhibit catalysts. The (10%)Ir/Al2O3–La2O3 + HAN95% and the (10%)CuO/Al2O3–La2O3 + ADN75% associations show lower decomposition temperatures, larger reaction rates and leads to higher amount of gas phase products, giving the most efficient systems.

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► Best results are obtained for the most concentrated HAN and ADN solutions.
► Good catalytic activity is demonstrated by low decomposition temperature.
► Fast reaction rate and large amount of products allow to choice the best catalyst.
► Best catalyst/monopropellant combinations: Ir-based/HAN95% and CuO-based/ADN75%.