Pressure effects on thermal decomposition reactions: a thermo-kinetic investigation

Abstract

The rate of chemical reactions is largely governed by three parameters namely, temperature, extent of the reaction/reaction model and pressure. Usually, the pressure is assumed to be constant and experiments are carried out at 0.101 MPa (1 atm) pressure. Ammonium perchlorate (AP) is an extensively used solid propellant oxidizer and its decomposition kinetics have been attracting significant research interest for quite some time. In the present study, the influence of pressure on the decomposition reaction and kinetics of AP is investigated. As well, we have synthesized CuO nanorods, characterized with (scanning electron microscopy) SEM, (high-resolution transmission electron microscope) HRTEM, (selected area diffraction) SAED and (powder X-ray diffraction) PXRD and added to AP as a catalyst and then the influence of pressure on the catalyzed decompositions are investigated. The decomposition behavior and kinetics were studied at three different pressures, 0.2, 0.6 and 1.2 MPa. The thermogravimetric analyzer and a high pressure differential scanning calorimeter were used for the studies. The studies reveal two different behaviors of catalyzed and non-catalyzed decomposition of AP under different pressure conditions. Promotion of secondary gas phase reactions by nitrogen and surface reactions on the nanocatalyst, promoting the oxidation reactions presumably lead to different decomposition behaviors of AP under different pressure conditions.