Thermal kinetics and decomposition mechanism of 1-amino-1,2,3-triazolium nitrate

Abstract

The thermal decomposition kinetics of 1-amino-1,2,3-triazolium nitrate(ATZ-NO₃) was investigated by non-isothermal TG-DTG at various heating rates(2, 5, 10, 15 and 20 °C/min). The results show that the thermal decomposition of ATZ-NO₃ consist of two stages corresponding to the losing of nitrate anion, substituent group and the splitting of triazole ring respectively. The kinetic triplets of the two stages were described by a three-step method. First, the differential Kissinger and intergral Ozawa methods were used to calculate the apparent activation energies(E) and pre-exponential factors(A) of the two decomposition stages. Second, two calculation methods(intergral Šatava-Šesták and differential Achar methods) were used to obtain several probable decomposition mechanism functions. Third, three judgment methods(average, double-extrapolation and Popescu methods) were used to confirm the most probable decomposition mechanism functions. Both reaction models of the two stages were random-into-nucleation and random-growth mechanisms with n=3/2 for the first stage and n=1/3, m=3 for the second stage. The kinetic equations for the two decomposition stages of ATZ-NO₃ may be expressed as $\frac{{da}} {{dt}} = 10^{13.60} \times e^{ - \frac{{128970}} {{RT}}} (1 - a)\left[ { - \ln (1 - a)} \right]^{ - \frac{1} {2}}$ and $\frac{{da}} {{dt}} = 10^{11.41} \times e^{ - \frac{{117370}} {{RT}}} (1 - a)\left[ { - \ln (1 - a)} \right]^{\frac{2} {3}}$. The thermodynamic parameters including Gibbs free energy of activation(ΔG ^≠), entropy of activation(ΔS ^≠) and enthalpy of activation(ΔH ^≠), for the thermal decomposition reaction were also derived.