The effect of water vapour and sulfur on the methane combustion reaction on Pd13 clusters: Insights from a first principles study

Catalytic methane combustion represents a highly efficient and environmentally-friendly approach, which can significantly reduce methane emissions in coal mines. However, the presence of water vapor and sulfides in coal mine methane exhaust gas can lead to catalyst poisoning deactivation. This article employs density functional theory calculations based on the GGA-PBE method to investigate the effects of water vapor and sulfur on methane combustion on Pd-13 clusters. According to thermodynamic parameters, we have determined the optimal reaction pathway for CH4 decomposition as CH4* -> CH3* -> CH2* -> CH* -> CHO*, while the optimal reaction pathway for CO2 formation is CH* -> CHO* -> CO* -> CO2*. Additionally, water vapor generates additional OH* radicals, which lower the adsorption energy of CH4 on Pd-13 clusters and alter the reaction pathway for methane oxidation, inhibiting the catalytic oxidation of CH4. Sulfides occupy the active sites on the catalyst surface, leading to a decrease in the activity of methane oxidation. These findings deepen our understanding of the mechanisms by which palladium-based catalysts catalyze methane combustion. Based on these findings, we have also proposed strategies for water and sulfur resistance of the catalyst, providing guidance for the future development of water-resistant and sulfur-resistant CH4 catalytic combustion catalysts.