High-Yield Production of Light Olefins from CO ₂ Hydrogenation over Co-Promoted Na–FeMn Catalysts

Efficiently converting CO 2 into high-yield light olefins via the CO 2 -modified Fischer–Tropsch synthesis (CO 2 –FTS) over iron-based catalysts remains a key challenge. Here, we report cobalt-promoted hydrogenation of CO 2 to light olefins over Na–FeMn catalysts. Incorporation of cobalt enhances the CO 2 conversion (59.6%) by accelerating CO formation via the reverse water–gas shift (RWGS) reaction, thereby increasing the availability of CO for subsequent FTS. Although cobalt increases the overall hydrogenation activity, the Na–FeMn framework maintains olefin formation pathways, leading to an improved light olefin yield of 22.33% with a selectivity of 39.6%. In situ X-ray diffraction (in situ XRD) and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) reveal the dynamic phase evolution of the catalyst and the transformation of surface intermediates under reaction conditions. The results indicate that cobalt primarily acts as a kinetic promoter that facilitates CO generation and intermediate turnover. This study clarifies the promotional role of cobalt in iron-based catalysts and provides insights into optimizing CO 2 hydrogenation toward light olefins.