Combustion inhibition of hydrogen-doped methane by carbon dioxide: A ReaxFF MD simulation

The transportation of hydrogen-blended natural gas is currently regarded as the optimal method for large-scale hydrogen utilization. However, the characteristics of hydrogen, such as low density, high diffusivity, and low ignition energy, increase the risk of pipeline leakage and explosion. This work employs the ReaxFF molecular dynamics (ReaxFF MD) method to simulate the inhibition effect of CO₂ on the combustion of hydrogen-blended methane. The temperature was set at 2400–3200 K, with a temperature gradient of 400 K and a fixed density of 0.02 g/cm³ . The evolution of the temperature, potential energy, and total product quantity over time is analyzed, and the distribution of the main products is investigated. The simulation results are verified using the reaction pathways and activation energies. It is found that CH₄ conversion is dominated by OH radicals generated from the key reaction O₂ + H ⇄ O + OH. With the addition of CO₂, the competition between CO₂+ H ⇄ CO + OH and H + O₂ ⇄ O + OH for H radicals intensifies, leading to a significant reduction in H radicals, which slows the combustion rate of CH₄ and delays the combustion process. This work elucidates the atomic-level kinetic mechanisms underlying CO₂ inhibition on hydrogen-doped methane, providing theoretical foundations to enhance safety measures in the production, storage, transportation, and utilization of hydrogen-methane systems.