Efficient thermal decomposition of ammonium perchlorate based on hollow spherical MnCo2O4.5 under carbon defect and morphology modulation

Abstract

In this study, a one-step preparation of carbon-rich MnCo₂O_4.5 precursors are achieved by adding glucose in a hydrothermal environment. Subsequently, MnCo₂O_4.5 catalytic materials with different carbon defect contents are obtained by controlling the calcination temperature, which enables the simultaneous release of great heat during the thermal decomposition of catalytic AP. This specially designed MnCo₂O_4.5 catalytic material has a hollow structure and exhibits good dispersion and a large specific surface area. The high-temperature decomposition temperature (T_HTD) of ammonium perchlorate (AP) is reduced from 473.48 ℃ to 301.32 ℃ after adding 2 wt% catalytic materials. The catalytic materials resulte in a threefold increase in the decomposition heat release of AP (from 888.26 J·g⁻¹ to 2616.98 J·g⁻¹). It also reduced the activation energy (E_a) by half, from 296.8 kJ·mol⁻¹ to 146.2 kJ·mol⁻¹, greatly facilitating the reaction. Consequently, the reaction rate (k) is doubled, from 0.44 s⁻¹ to 0.97 s⁻¹. The bimetallic synergistic effect of MnCo₂O_4.5 itself, combined with the carbon material, significantly improved its performance in catalysing the thermal decomposition of AP. In addition, the combustion of carbon materials not only provides additional heat for AP pyrolysis but also further enhances the combustion of the Hydroxy Terminated Polybutadiene Composite Solid Propellant (HTPB-CSP) system. The introduction of this catalytic material reduces the CSP ignition delay time by 13 ms, allowing for a faster and more intense combustion process.