ZrO2 supported Fe-based catalysts for direct synthesis of light olefins via CO2 hydrogenation

Abstract

The catalytic hydrogenation of carbon dioxide (CO2) to light olefins provides a sustainable route for producing key chemical intermediates and reducing dependence on fossil-based feedstocks. In this study, FeK, FeCoK, and FeCuK catalysts supported on ZrO2 were synthesized by a simple wet impregnation method and evaluated for CO2 hydrogenation. The goal of the study was to understand how secondary metal promoters (Co or Cu) influence the structural and electronic properties of K-promoted Fe/ZrO2 catalysts and how these modifications affect CO2 conversion and product selectivity. Among the catalysts tested, FeCoK/ZrO2 showed the highest performance, achieving around 40% CO2 conversion and 30% light-olefin selectivity, compared with 40% conversion and 22% selectivity for FeCuK/ZrO2 under identical conditions (400 degrees C, 3 MPa, H-2/CO2 = 3). The FeCuK catalyst exhibited higher CO yield, suggesting enhanced reverse water-gas shift (RWGS) activity, while Co promotion facilitated the formation and stabilization of iron carbides, improving chain growth and olefin selectivity. These findings demonstrate that the addition of Co or Cu effectively tunes the competition among RWGS, methanation, and hydrocarbon chain-growth pathways. Furthermore, the simple impregnation method yielded catalytic behavior comparable to more complex synthesis approaches, highlighting its potential scalability for CO2-to-olefin conversion.