Tuning Zn/Fe ratio to control CO₂ hydrogenation pathways toward DME and light olefins

The hydrogenation of CO₂ to value-added chemicals offers a viable pathway for carbon utilization, yet controlling the product distribution remains a major challenge. Herein, we demonstrate that the Zn/Fe ratio in ternary Cu–Zn–Fe catalysts serves as a key descriptor for steering reaction pathways between oxygenate and hydrocarbon formation. By systematically tuning the Zn/Fe ratio, distinct catalytic behaviors are achieved through modulation of metal dispersion and interfacial interactions. Among the investigated catalysts, CZ(1)F(3) exhibits the highest CO₂ conversion (34.1%) and a coupled product distribution with significant selectivity toward dimethyl ether (DME, 18.2%) and light olefins (C₂–C₄⁼ ≈ 31.4%). The simultaneous formation of DME and olefins suggests the possibility of a sequential reaction pathway in which methanol/DME-derived intermediates may contribute to olefin formation. Methane formation is observed across all catalysts, indicating the presence of competing methanation pathways under the investigated conditions. The superior performance of CZ(1)F(3) is attributed to optimized Cu–Zn–Fe interfacial interactions, which balance CO₂ activation and C–C coupling reactions. The enhanced performance of CZ(1)F(3) is further supported by H₂-TPR and CO₂-TPD analyses, which reveal improved low-temperature reducibility and an optimal distribution of moderate basic sites, facilitating efficient H₂ activation and CO₂ adsorption–desorption dynamics. These findings establish Zn/Fe ratio engineering as an effective strategy for directing CO₂ hydrogenation pathways toward high-value products, particularly light olefins.