Insight into the synergistic effect of copper and sodium over metal organic framework-derived Fe-based catalyst for CO2 hydrogenation to aromatics

One-step hydrogenation of carbon dioxide (CO2) to aromatics is a promising strategy for relieving the stress of fossil fuels. Here, a copper and sodium co-modified Fe-based catalyst (3-NFC-5) was synthesized through the pyrolysis of Cu-doped MIL-101(Fe) and Na impregnation. After combining with HZSM-5, 42.11% CO2 conversion and 50.68% total aromatics selectivity was achieved. Through multiple characterization and DFT calculations, the synergistic promotion of Na and Cu on light olefins intermediate production was revealed. Na was crucial for COOH* formation as the intermediate for reverse water gas shift reaction (RWGS), whose concentration could be further enhanced after Cu modification. Controlled C-C coupling towards C2-C4 hydrocarbons was realized by the enhanced CO non-dissociative activation and the increased content of χ-Fe5C2 after Cu doping, which was responsible for the inhibited surface CHx* concentration and selective production of light olefins, respectively.