Highly Efficient Conversion of CO2 to C2–C4 Olefins on Co- and Zn-Copromoted Na-Modified Fe2O3 Catalysts with Suppressed In Situ Oxidation of Fe5C2

Abstract The hydrogenation of CO2 to higher hydrocarbons (C2+-hydrocarbons), especially to C2–C4 olefins, represents an effective strategy for the high-value utilization of this renewable raw material. Although Fe-based catalysts are typically used for this reaction and demonstrate promising industrial performance, they are prone to deactivation due to H2O-mediated oxidation of the catalytically active Fe5C2 phase under reaction conditions. In this regard, we introduce two transition-metal promoters, Co and Zn, to enhance the on-stream stability of Na-modified Fe-based catalysts. The developed Na–Fe3Co1Zn1 catalyst achieved a space-time yield of the formation of C2–C4 olefins of 27.6 mmol·gcat–1·h–1 at 47.1% CO2 conversion at 340 °C and 20 bar using an industrially relevant feed. This productivity is about 2 times higher than that of the undoped Na–Fe catalyst and remains stable over 120 h on stream, placing it among the most effective state-of-the-art catalysts reported to date. This catalyst also achieves a higher yield of C2+ hydrocarbons compared to most previously developed catalysts, while the yields of CO and CH4, which are side products, are markedly lower.