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

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 °C, 3 MPa, H₂/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.