Synergistic CoFeZn Trimetallic Catalysts Enabling Efficient Conversion of CO2-Rich Syngas to Olefins with Negative Carbon Emission

Direct conversion of CO2-containing syngas into value-added olefins provides an effective route for the utilization of carbon-based resources. However, it remains a grand challenge to simultaneously achieve the coconversion of CO and CO2 due to the distinct activation behaviors of their C–O bonds. Herein, a K- and Zn-doped CoFe alloy carbide catalyst was prepared for the efficient conversion of CO2-rich syngas into olefins with negative carbon emission. The as-prepared CoFeZn catalyst, featuring (CoxFe1–x)5C2 as the active phase, achieves 49.5% olefin selectivity at 98.0% CO and 16.7% CO2 conversions, with a high olefin space-time yield of 163.7 mg·gcat–1·h–1 and stability of 110 h. Compared with traditional Fe-based catalytic systems that generate substantial CO2 byproducts, the Zn-(CoxFe1–x)5C2 catalyst not only significantly inhibits CO2 formation but also converts CO2 into target olefins. Characterization results suggest that Co is uniformly doped into Fe5C2 to form (CoxFe1–x)5C2, while the addition of Zn enhances H2 dissociation and reverse water gas shift activity. The synergistic effect of Co, Fe, and Zn promotes the adsorption and activation of CO/CO2, where CO2 is converted to CO via the RWGS reaction, followed by the Fischer–Tropsch synthesis route to produce olefins. This work provides a promising strategy for designing efficient catalysts to coconvert CO and CO2, eliminating the need for CO2 removal in syngas processing.