Thermal decomposition mechanism of some hydrocarbons by ReaxFF-based molecular dynamics and density functional theory study

•The pyrolysis mechanisms of hydrocarbons are investigated using ReaxFF molecular dynamics and DFT methods.•The initiation reactions and chain reactions of pyrolysis are detailed analyzed.•The effects of pressure, temperature and molecular structure are considered in the thermal decomposition of hydrocarbons.•The kinetic analysis of n-pentane, isopentane, neopentane and cyclopentane pyrolysis has been carried out.