Thermal behavior and decomposition mechanism of azobenzene by using kinetic calculation method and molecular dynamics simulation method

In the work, both elevated thermal and isothermal experiments of azobenzene were carried out by using SENSYS Evolution DSC. Kinetic parameters and decomposition mechanism were figured out by using Kinetic Calculation (KC) method and Molecular Dynamics Simulation (MDS) method. The results show that a first endothermic and following exothermic behavior appears distinctly in the thermal decomposition process of azobenzene; the apparent activation energy keeps approximately constant at the stage of 0.1 <_ alpha <_ 0.4, and then reduces gradually as the reaction goes on; the thermal decomposition behavior of azobenzene can be described by Sestak-Berggren mechanism on here; The step without adequate free radicals and the step with exponential growth of free radicals dominate respectively the stable decomposition process at initial stage and the self-accelerating decomposition process at autocatalytic stage; Based on Semenov model, the calculated SADT of azobenzene is 380.5 celcius, when packed in 25 kg standard package. (c) 2022 Institution of Chemical Engineers. Published by Elsevier Ltd. All rights reserved.

Automated summary

In this work, elevated thermal and isothermal experiments of azobenzene were conducted using SENSYS Evolution DSC. Kinetic parameters and decomposition mechanism were determined using Kinetic Calculation (KC) method and Molecular Dynamics Simulation (MDS) method. The results demonstrate that azobenzene exhibits a distinct first endothermic and subsequent exothermic behavior during thermal decomposition. The apparent activation energy remains relatively constant in the range of 0.1 <_ alpha <_ 0.4 and gradually decreases as the reaction proceeds. The thermal decomposition behavior of azobenzene can be described by the Sestak-Berggren mechanism. At the initial stage, the decomposition process is controlled by the lack of sufficient free radicals, while at the autocatalytic stage, it is governed by the exponential growth of free radicals. Based on the Semenov model, the self-accelerating decomposition temperature (SADT) of azobenzene is calculated to be 380.5 degrees Celsius when packed in a 25 kg standard package.