Thermal behavior and decomposition kinetics of nitro-1,2,4-triazol-3-one by gas manometric technique

Isothermal decomposition kinetics play an important role in the stability assessment, risk assessment, and reaction mechanism inference of energetic materials. Herein, the thermal decomposition of nitro-1,2,4-triazol-3-one (NTO) was investigated using a self-development isothermal decomposition gas manometric device at both high and low temperature ranges. The kinetic parameters were calculated by model-free method and model-fitting method. The results show that the activation energies determined by these two methods are in good agreement. At 473-493 K, the entire decomposition process of NTO showed two distinct stages. The activation energy (E-a) and pre-exponential factor (lnA) in the first stage are 260.1 +/- 11.5 kJ mol(-1) and 52.5 +/- 2.9 s(-1), respectively, while they are 166.0 +/- 24.5 kJ mol(-1) and 28.4 +/- 6.1 s(-1) in the second stage. At 383-423 K, the initial decomposition process of NTO was investigated. During this process, E-a is 99.8 +/- 3.2 kJ mol(-1) and lnA is 11.5 +/- 1.0 s(-1). According to the kinetic results, a mechanism was speculated to be the transition of a rate-limiting step from nucleation and nuclei growth to the gas diffusion. Moreover, the E-a-lnA sets were found to lie on the kinetic compensation regression line, which indicates that the kinetic data in this work are reliable. All the results will further support and complement the kinetic database of NTO.

Automated summary

Isothermal decomposition kinetics play a crucial role in assessing the stability, risk, and reaction mechanism of energetic materials. In this study, the thermal decomposition of nitro-1,2,4-triazol-3-one (NTO) was investigated using a self-developed isothermal decomposition gas manometric device. The activation energies and pre-exponential factors were calculated, and the results indicate a two-stage decomposition process for NTO. The study also suggests a mechanism involving a transition from nucleation and nuclei growth to gas diffusion. The kinetic data obtained from this study are reliable and contribute to the kinetic database of NTO.