The catalytic hydrogenation of CO 2 to light olefins remains limited by poor olefin selectivity and excessive methane formation. Here, we investigate the effect of dual alkali promotion on tuning the redox and electronic properties of Fe–Zn catalysts under mild reaction conditions. A series of Fe–Zn catalysts with controlled sodium to potassium ratios were prepared, and structural characterization confirmed that the ZnFe 2 O 4 spinel phase was preserved across all samples. Notably, X-ray photoelectron spectroscopy indicates that co-promotion with sodium and potassium modifies the surface Fe 3 ⁺/Fe 2 ⁺ ratio beyond the trend observed in single-alkali systems, suggesting a cooperative electronic modulation. This cooperative effect is associated with enhanced CO 2 conversion pathways and suppressed deep hydrogenation. As a result, the balanced Na–K/Fe–Zn catalyst achieved the highest C 2 –C 4 olefin selectivity (33.36%) while maintaining low methane formation (12.25%), among the investigated catalysts. A preliminary tandem coupling with HZSM-5 further illustrates the potential for downstream upgrading of in situ olefins into aromatics. Overall, these results highlight the potential of combined sodium and potassium promotion as an effective approach for enhancing light olefin production from CO 2 over Fe–Zn catalysts.
Istadi et al. (Mon,) studied this question.