Study on the activation mechanism of O-enhanced methane adsorbed on Pd-Cu catalyst

Compared with traditional combustion, methane catalytic combustion has the advantages of low combustion temperature, clean and high efficiency, and it has good application prospects in natural gas vehicles, solid oxide fuel cell and other fields. In order to reveal the mechanism of dehydrogenation of methane on Pd-Cu clusters with different doping ratios, the density functional theory (DFT) is used to calculate the direct dehydrogenation and O-assisted dehydrogenation of CH₄* in different clusters. The calculation results show that the doping of Pd atoms increases the adsorption capacity of Cu(111) surface, and in the process of direct dehydrogenation, the doping of Pd not only reduces the energy barrier from 2.56 to 2.43 eV, but also changes the rate determining step from CH*+*→C* + H* to CH₄*+*→CH₃* + H*. Pre-adsorbed O can significantly reduce the energy barrier of methane dehydrogenation, and the rate determining steps are CH₄* + O*→CH₃* + OH*. The highest energy barrier of O-assisted dehydrogenation of CH₄* is Cu(111)(1.56 eV)>Pd₆Cu(111)(1.44 eV)>Pd₂Cu(111)(1.38 eV) on three clusters, which indicates that the addition of Pd has improved the performance of direct dehydrogenation and O-assisted dehydrogenation.