Insight into pyrolysis mechanism of p-aminophenol crystal based on thermogravimetric analysis and ReaxFF molecular dynamics

Abstract

Antioxidant additives is used for aviation fuel to inhibit oxidative deposition during long-term storage. As a highly reactive additive with difunctional groups, the high-temperature cracking reaction mechanism of p-aminophenol is worthy of clarification. This work studies the pyrolysis kinetics of p-aminophenol based on thermogravimetric analysis and reveals the detail of phase and chemical transfer at the atomic level by heating simulations of ReaxFF MD. Furtherly, following multiple temperature points by isothermal simulation magnifies and observes the crystal cracking reaction mechanism. It reveals the pyrolysis kinetic mechanism that the consumption of p-aminophenol forms a gradually shrinking core with a process from disordered collision to ordered decomposition in endothermic reaction. The high temperature of the phase transition process was triggered by weaken the interaction of structural rings, and increases the collision frequency caused by the of volatile compounds. The dehydrogenation of the difunctional groups NH₂ and OH was the most important initial cracking pathway for p-aminophenol. Thereby hydrogen radicals initiate a chain reaction of functional group dissociation. Increasing temperature performs the selectivity for the cracking, which is a key factor in the substitution of amino dehydrogenation by amino dissociation during the cracking process. It also effects the formation pathway of polycyclic aromatic hydrocarbons. In this work, the high-temperature cracking mechanism of antioxidant additives component p-aminophenol is explored through experimental and simulation methods, which provides a theoretical support for the safe aviation fuel.