engleski

Study of Thermal Decomposition Kinetics of Low-temperature reaction of Ammonium perchlorate by Isothermal Thermogravimetry

The results of numerous investigations of ammonium perchlorate decomposition process show that there is considerable discrepancy in the values of the activation energy obtained. This discrepancy may arise from several reasons: the use of different kinetic equations in treating kinetic data, different experimental methods applied and different testing conditions used. Another reason might be the fact that this decomposition is unusually complex. Probably one of the most striking characteristics of decomposition is that at low temperatures ammonium perchlorate decomposes only to the extent of about 30%, living a residue which is chemically identical with the original salt, whereas above 300 oC it decomposes completely. The kinetics of the thermal decomposition of ammonium perchlorate at temperatures between 215 and 260 oC is studied in this work by measuring the sample mass loss as a function of time, applying the isothermal thermogravimetry method. From the maximum decomposition rate-temperature dependence, two different decomposition stages, corresponding to two different structural phases of ammonium perchlorate, are identified. For the first region (215-235 oC), corresponding to the orthorhombic phase, the mean value of the activation energy of 146.3 kJ mol-1, and the pre-exponential factor of 3.43 1014 min-1 are obtained, whereas for the second region (240-260 oC), corresponding to the cubic phase, the mean value of the activation energy of 153.3 kJ mol-1, and the pre-exponential factor of 4.11 1014 min-1 are obtained.

ammonium perchlorate; kinetics; decomposition

nije evidentirano