Synergistic CoFeZn Trimetallic Catalysts Enabling Efficient Conversion of CO ₂ -Rich Syngas to Olefins with Negative Carbon Emission

Direct conversion of CO 2 -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 CO 2 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 CO 2 -rich syngas into olefins with negative carbon emission. The as-prepared CoFeZn catalyst, featuring (Co x Fe 1– x ) 5 C 2 as the active phase, achieves 49.5% olefin selectivity at 98.0% CO and 16.7% CO 2 conversions, with a high olefin space-time yield of 163.7 mg·g cat –1 ·h –1 and stability of 110 h. Compared with traditional Fe-based catalytic systems that generate substantial CO 2 byproducts, the Zn-(Co x Fe 1– x ) 5 C 2 catalyst not only significantly inhibits CO 2 formation but also converts CO 2 into target olefins. Characterization results suggest that Co is uniformly doped into Fe 5 C 2 to form (Co x Fe 1– x ) 5 C 2, while the addition of Zn enhances H 2 dissociation and reverse water gas shift activity. The synergistic effect of Co, Fe, and Zn promotes the adsorption and activation of CO/CO 2, where CO 2 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 CO 2, eliminating the need for CO 2 removal in syngas processing.