Catalytic effect of Fe2O3, Mn2O3, and TiO2 nanoparticles on thermal decomposition of potassium nitrate

The kinetic and activation energies of thermal decomposition of KNO3 as an oxidizer in pyrotechnic compositions were studied in the presence of Fe2O3, Mn2O3, and TiO2 nanoparticles as catalysts, using thermogravimetric analysis under argon atmosphere at different heating rates (10, 15, and 20 K min(-1)). The prepared nanoparticles were characterized by XRD patterns, SEM images, and BET surface area analysis. For verification of data, the activation energies for thermal decomposition of KNO3 were calculated using non-isothermal isoconversional methods of KAS, OFW, and Friedman for different conversion fraction (alpha) values in the range 0.1-0.9. The activation energies were 201.6-208.2, 170.0-177.9, 173.9-181.6, and 213.0-223.8 kJ mol(-1), respectively, in the absence and presence of 5 mol% of Fe2O3, Mn2O3, and TiO2. The results indicated that while Fe2O3 and Mn2O3 nanoparticles have catalytic effects, TiO2 nanoparticles show inhibitory effect on the thermal decomposition of KNO3.