Mechanisms for direct methane conversion to oxygenates at low temperature

• Catalysts for C 1 and C 2+ oxygenates synthesis from CH 4 are encapsulates. • The activities and reaction mechanisms of different catalysts are compared. • Potential catalysts and technologies to synthesize C 2+ oxygenates are discussed. • Future research directions in C 2+ oxygenates synthesis are discussed. Methane’s abundant and diverse reserves make it a promising feedstock for clean fuels and chemicals. To replace the current energy and capital intensive syngas-based indirect process, it is important to develop economically viable and environmentally responsible technology for converting CH 4 into value-added products, such as oxygenates. Direct catalytic conversion of CH 4 into oxygenates under mild conditions is a significant challenge within catalysis due to CH 4 being relatively inert and over-oxidation resulting in low selectivity. The development of high-efficiency and low-temperature C–H bond activation catalyst is the key to translation of the catalytic CH 4 conversion into an industrial implication. This review encapsulates typical catalysts for C 1 and C 2+ oxygenates synthesis from CH 4 , and compares their activities as well as corresponding homogeneous and heterogeneous reaction mechanisms. Also, the potential heterogeneous catalysts and new technologies to synthesize C 2+ oxygenates from CH 4 and CO x ( x = 1,2) are highlighted. Moreover, future research directions in C 2+ oxygenates synthesis, composite catalyst development, reaction mechanism analysis, and new reactor designs are discussed.