H/D exchange studies of methane activation mechanisms in heterogeneous catalysis

The development of technologies for the efficient conversion of methane and other light hydrocarbons is becoming vital to the chemical industry. The main technologies for methane conversion are based on solid and liquid catalysts such as metals, oxides and oxide-supported metals. Methane is a highly stable molecule, and the analysis of the catalytic activity of materials with respect to the C-H bond cleavage in methane is of paramount importance for the development of novel methane conversion catalysts. One of the most promising methods for studying methane activation over a catalyst is H/D isotope exchange between the gas and condensed phases. The method provides reliable in situ information on the cleavage of chemical bonds in molecules and allows researchers to elucidate the elementary steps of catalytic methane activation and the stable intermediates involved in the activation process. This paper focuses on the critical analysis of H/D isotope exchange studies of the methane activation mechanism over various metals, oxides, composites, and other catalysts, from the earlier studies to the recent advances in the field. The existing theoretical and experimental approaches to study the H/D exchange between methane and a catalyst are discussed in the paper. A critical analysis of the structure-composition-catalytic activity relationships of the catalysts with respect to methane activation is provided.