Overview of Direct Methane Conversion to Chemicals with C–O and C–C Bonds

Abstract

An overview of the conversion of methane to various chemicals, i.e., methanol, aromatic hydrocarbons, and olefins, via heterogeneous, homogeneous, and biological catalysts is provided, along with the social considerations and global circumstances surrounding methane conversion. The scope is mainly restricted to the ``direct conversion of methane'' to produce chemicals with C--O and C--C bonds, meaning that processes involving synthesis gas as an intermediate are not considered. To provide an understanding of the way in which the heterogeneous, homogeneous, and biological catalysts and their reaction environments control the formation of reaction intermediates from methane and contribute to the formation of C--O or C--C bonds to produce methanol, methanol derivatives, or hydrocarbons via the direct conversion of methane; various examples of direct methane conversion are discussed in terms of their mechanistic and functional aspects. Although no industrial processes for the direct conversion of methane to chemicals have been implemented, the development of such processes is essential from both economic development and energy security points of view. For scientists and engineers, the development of a next-generation process for direct methane conversion represents a ``grand challenge'' in chemistry, independent of trends in the larger world, such as the discovery of shale gas and the drive to reduce carbon dioxide emissions.