Activation of Methane by Clean and Chemically Modified Single Crystal OxideSurfaces. Annual Report, October 1992-September 1993

摘要

The coupling of methane to ethane over model MgO catalysts as well as certainmetal surfaces prepared under well-controlled, ultrahigh vacuum conditions has been studied using a combination of surface science techniques and reaction kinetic measurements. The utilization of electron energy loss spectroscopy has allowed the characterization of a variety of defects in the catalysts and the identification of the active sites which are responsible for the methane coupling reaction. For oxide surfaces, a quantitative correlation between the density of specific defects and the ethane formation rate indicates that (Li(1+)O(1-)) centers are not likely directly involved in the methane activation steps as previously proposed. For metal surfaces, i.e. ruthenium, surface science and kinetic studies have shown the nature of the carbonaceous residue responsible for product formation as well as the specific intermediates involved in the transition from reactants to product.