MgAl2O4 nanoparticles: A new low-density additive for accelerating thermal decomposition of ammonium perchlorate

Developing low-density additives with high activities is significantly important for thermal decomposition of ammonium perchlorate and the relative technical applications. In this paper, nanoparticles of magnesium aluminate (MgAl2O4) with a low density of 3.02-3.17 g cm(-3) were synthesized by a self-generated template path, in which citric acid was introduced to ensure homogeneous distribution of metal cations at atomic level and serve as the carbon source of the self-generated carbon template. Carbon template was generated by pyrolysis and carbonization of citrate after calcinations at 800 degrees C in N-2, and then removed with annealing in air at high temperatures, resulting in porous MgAl2O4 with a specific surface area as high as 291 m(2) g(-1). Depending on the annealing temperatures, the primary sizes of MgAl2O4 nanoparticles that built up the porous structures were adjusted from 6.2 to 24.7 nm. The structural characteristics of MgAl2O4 nanoparticles were systematically studied by X-ray diffraction, transmission electron microscopy, Braun-Emmet-Teller analysis, and the catalytic role were evaluated by thermal decomposition of ammonium perchlorate. All samples were indicated to be X-ray-pure MgAl2O4, among which MgAl2O4 nanoparticles with a largest surface area of 291 m(2) g(-1) and pore volume of 0.24 cm(3) g(-1) was proved to have an optimum catalytic activity: exothermic peaks of AP thermal decomposition shifted towards the lower temperatures by 78.3 degrees C for high-temperature decomposition process. The relative kinetic process was also investigated.