Methane Activation On Typical Metal Oxide Clusters

The activation and conversion of methane into more valuable chemicals have attracted much attention in energy,chemical engineering and environment,in which the selection of catalysts plays a key role.As a new frontier in heterogeneous catalysis,oxide is a commonly used catalyst or carrier,single-atom catalysis with noble metals has great advantages in improving the activity and selectivity of the catalytic reactions.In this paper,the micro-mechanism of the reaction is studied by using the cluster model,we will investigate the reaction mechanisms of methane activation catalyzed on nanosized niobium oxide cluster cations systematically by means of density functional theory and mass-spectrometry based experiments and compared with that on vanadium oxides.Adsorption of a single gold or silver atom on vanadium oxide clusters and reaction with methane.As well as preliminary study of related clusters and methane activation reaction.The reactivity of?Nb2O5?N⁺ clusters decreases as the N increases,and it is higher than that of?V₂O₅?N⁺ for N ? 4.The difference of the reactivity with respect to the cluster size and metal type?Nb vs V?was attributed to thermodynamics,kinetics,the electron capture ability,and the distribution of the unpaired spin density.Nanosized Nb oxide clusters show higher Hydrogen atom abstraction reactivity than V oxides,indicating that niobia may serve as promising catalysts for practical methane conversion.The bonding properties between a single atom and its support have a close relationship with the stability and reactivity of single-atom catalysts.The single noble metal atom Au or Ag tends to be adsorbed on the periphery of the V oxide clusters.When methane is adsorbed on Au V₃O_y^+/-/0 clusters,Au on AuV₃O_y^+/-/0 clusters is easier to activate methane than oxygen atoms.For open-shell cation clusters and neutral clusters,methane is activated by Au atoms?adsorbed on O sites?,and Au is easier to get electrons.For anionic clusters,methane tends to adsorb on O.The proposed research will be helpful in explaining the experimentally observed phenomena of the catalytic reactions,determining the composition and structure of the catalytic active centers,revealing the microscopic mechanism of catalytic reaction,and obtaining the main factors that determine the reactivity and selectivity.It will thus provide valuable theoretical guidance for the rational design of highly efficient and relatively inexpensive catalysts for methane activation and conversion.