Insight into Acetic Acid Synthesis from the Reaction of CH4and CO2

The reaction of CH4 and CO2 to produce acetic acid is an atom-efficient way for using carbon resources and for mitigating CO2 emissions. This article provides a critical assessment of the progress in this catalytic reaction from the perspective of identifying and constructing the active sites. We elucidate how Cu- and Zn-based catalysts with different structures are used for the activation of CH4 and CO2. The differences in the metal oxidation state may affect the adsorption of CH4 and CO2 and consequently change the activation barriers for the dissociation of the C–H bond of CH4 and the C–C coupling reaction. We discuss how the active sites and transition states can be modified by the location of metal sites, the framework environment, and the promotion effect of different acid sites. We also compare different technologies, including catalyst pretreatment, preactivation with CO2, tandem reaction, and plasma-driven catalysis for the CH4 and CO2 conversion. We conclude by identifying opportunities for improving the efficiency of heterogeneous catalysts for this important reaction.