Alternative Oxidants for the Catalytic Oxidative Coupling of Methane

The catalytic oxidative coupling of methane (OCM) to C2 hydrocarbons with oxygen (O2-OCM) has garnered renewed worldwide interest in the past decade due to the emergence of enormous new shale gas resources. However, the C2 selectivity of typical OCM processes is significantly challenged by overoxidation to COx products. Other gaseous reagents such as N2O, CO2, and S2 have been investigated to a far lesser extent as alternative, milder oxidants to replace O2. Although several authoritative review articles have summarized OCM research progress in depth, recent oxidative coupling developments using alternative oxidants (X-OCM) have not been overviewed in detail. In this perspective, we review and analyze OCM research results reporting the implementation of N2O, CO2, S2, and other non-O2 oxidants, highlighting the unique chemistries of these systems and their advantages/challenges compared to O2-OCM. Current outlook and potential areas for future study are also discussed.