Facile fabrication of carbon nanotubes-encapsulated cobalt (nickel) salt nanocomposites and their highly efficient catalysis in the thermal degradation of ammonium perchlorate and hexogen

For reducing particle aggregation and improving catalytic activities of metal salts in composite solid propellants, ten cobalt and nickel compounds were encapsulated into the channels of oxidized carbon nanotubes (CNTs) by ultrasonication, which was proven by TEM, SEM, XRD, Raman, XPS, etc. The catalytic performances of the nanocomposites for ammonium perchlorate (AP) and hexogen (RDX) thermal degradation were evaluated by the DSC technique and the results revealed that the composites exhibit significant effects on the thermal decomposition of AP and RDX. Among them, 5 wt. % Co(NO3)2@CNTs(D1) as the catalyst increased the released heat of AP from 746.53 J/g to 2489.26 J/g, higher in catalytic efficiency than CoO@CNTs(D1) (1791.29 J/g), and advanced the peak temperature of AP at the high-temperature decomposition stage from 406.6°C to 312.4°C; while 1 wt. % Ni(NO3)2@CNTs(D1) as an additive enhanced the pyrolytic heat of RDX approximately three times and was more active than that of NiO@CNTs(D1). Kinetic studies showed that the activation energies of AP and RDX were sharply decreased with Co(NO3)2@CNTs(D1) and Ni(NO3)2@CNTs(D1) as additives. In addition, the thermal decomposition mechanism of RDX was studied by TG-FTIR-MS and it was found that the as-prepared nanocomposites promoted the cleavage of the C-N bonds of RDX and the generation of N2O gas.