Mechanism and safety analysis of acetylene decomposition explosion: A combined ReaxFF MD with DFT study

Abstract

• The ReaxFF MD method reveals the reaction path of acetylene pyrolysis, and the kinetic model is obtained by DFT calculation. • Acetylene reacts with itself in the form of vinylidene to generate methylene cyclopropene and vinyl acetylene as initial adducts. • Free radical polymerization initiates the explosive decomposition of acetylene. • Obtain the critical temperature and pressure curve for the explosive decomposition of acetylene. The internal reaction mechanism of the explosive decomposition of acetylene was systematically studied by the combination of reactive force field molecular dynamics simulation and density functional theory calculations. ReaxFF MD simulations reproduced the main pyrolysis products of acetylene observed in the actual pyrolysis experiments. Kinetics study showed that the pyrolysis of acetylene was predominated by molecular addition reactions at low temperatures, while the free radical chain reactions occur at higher temperatures. Density functional theory (DFT) is employed to calculate the activation energy barrier and other thermodynamic parameters for the reaction route steps revealed by ReaxFF simulations. Furthermore, the critical temperature and pressure of acetylene decomposition explosion were obtained by numerical calculation. These results elucidate the complicated reaction process of acetylene explosion and provide scientific guidance for the effective prevention and management of explosive accidents and a theoretical foundation for explosion suppression technology development.