Low-Temperature Light-off MnOx -Na2 WO4 -Based Catalysts: A Step Forward to OCM Process Industrialization.

Oxidative coupling of methane (OCM) catalyzed by MnOx -Na2 WO4 -based catalysts has great industrial potential to convert CH4 directly to C2-3 products, but the high light-off temperature is a big challenge to OCM commercialization. The reaction mechanism studies disclosed that O2 /CH4 -activation relevant "Mn2+ ↔Mn3+ " redox cycle is tightly linked with the catalyst light-off. One concept is thus put forward that the OCM light-off temperature could be lowered once a "Mn2+ ↔Mn3+ " redox cycle was established to be triggered at low temperature over MnOx -Na2 WO4 -based catalysts. The relevant studies in recent years are reviewed, showing that the establishment of low-temperature light-off "Mn2+ ↔Mn3+ " redox cycle over the MnOx -Na2 WO4 -based catalysts indeed works effectively toward a low-temperature light-off OCM process. Moreover, three perspectives for the OCM industrialization are discussed based on this concept, including monolithic catalyst, fluidized-bed method and chemical-looping process.