Surface-generated gas-phase radicals, which are the subject of this study, may function as important intermediates in several important partial and complete oxidation reactions. Two examples are the role of CH3 radicals in the oxidative coupling of CH4 and the role of OH radicals in the catalytic combustion of CH4. Although the gas phase chemistry of simple hydrocarbon radicals is reasonably well understood, very little is known about the reactions that occur between these radicals and metal oxide surfaces. Moreover, the formation of hydroxyl radicals over oxides is a largely unexplored area of catalysis. Recent work in the laboratory has been devoted to the reactions of methyl radicals with reactive metal oxides, and the production of hydroxyl radicals under rate limiting conditions. This paper describes reactions of CH3 radicals with metal oxides; catalytic conversion of CH3 radicals to CH3OH and HCHO; identification of surface-generated benzyl radicals; and formation of OH radicals under rate limiting conditions.

The conversion of light hydrocarbons with solid catalysts is an important class of reactions in the chemical and energy industries. Our knowledge on the exceedingly complex reaction kinetics of these catalytic reactions, especially the inter-influence between the reactions on catalyst and those in the gas phase, lags behind the requirement of technology development to improve efficiency and reduce emissions.