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.
The use of alternative oxidants for the oxidative dehydrogenation of propane (ODHP) is a promising strategy to suppress the facile overoxidation to COx that occurs with O2. Gaseous disulfur (S2)...
The catalytic oxidative dehydrogenation of propane (ODHP) is a challenging reaction due to facile competing overoxidation to COx. The gaseous disulfur molecule, S2, is isoelectronic with O2 and has been shown to act as an alternative, “soft oxidant” for the analogous process (SODHP) over bulk metal sulfide catalysts. However, these bulk catalysts suffer from low surface areas and ill‐defined active sites – issues that might be addressed with a supported catalyst. Here we investigate supported V/Al2O3 materials for SODHP. We show that these catalysts are highly selective for propylene, far surpassing the yields of the prior bulk systems. Isolated sulfided vanadium species are found to be more active and selective than crystalline vanadium sulfide. Additionally, we compare the S2 and O2 oxidants over sulfided and calcined V/Al2O3 materials, respectively, and find that the propylene selectivity is enhanced using S2 as the oxidant. These results suggest that sulfur is a promising soft oxidant that can be used to achieve high propylene selectivities over supported metal sulfides.
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