Steelmaking Wastes as Catalysts for the Circular Conversion of CO2 to Syngas

Reutilizing steel industry waste is increasingly important for reducing its adverse environmental impact and associated disposal costs. Conventional utilization methods offer low added value and are often constrained by the waste’s physical and chemical properties. In contrast, catalytic applications can overcome these limitations. This study investigates the catalytic performance of electric arc furnace slag (EAFS), electric arc furnace dust (EAFD), and ladle furnace slag (LFS) in the reverse water–gas shift (RWGS) reaction, which converts CO2 into CO, a valuable feedstock or reducing agent. Using a CO2/H2 gas mixture at a 1:3 ratio, the catalysts were evaluated for their activity, long-term stability over a 24 h isothermal reaction at 750 °C, and tolerance to sulfur following exposure to 150 ppm of H2S. All materials demonstrated 100% CO selectivity and excellent thermal stability. Notably, EAFD showed only a reversible decrease in activity upon H2S exposure, significantly outperforming the 3%Pd/Ce/Al2O3 reference catalyst, which exhibited an irreversible loss. In situ X-ray diffraction (XRD) revealed a correlation between FeO/Fe transformations and the activity of EAFD and EAFS, while LFS showed CaCO3 formation and decomposition as the dominant process. These findings highlight the potential of steelmaking wastes as efficient sulfur-resistant catalysts for large-scale CO2 utilization via the RWGS reaction.