Potassium-driven pathway modulation in CO₂ hydrogenation: Tuning ethanol and liquid fuels synthesis over FeCuAl catalysts

This study explored the influence of potassium (K) loading on CO₂ hydrogenation, with an emphasis on modulating products selectivities towards C₅₊ hydrocarbons and ethanol. A series of K(x)/FeCuAl catalysts were synthesized using a co-precipitation method, enabling precise control over K loading. The results demonstrated that K plays a critical role in modifying the catalytic pathway, enhancing C₅₊ hydrocarbon selectivity while concurrent regulating ethanol production. Specifically, moderate K loading (1.6 wt%) yielded the highest ethanol space-time yield (STY) of 603 g_AcHkg_cat⁻¹h⁻¹, whereas increased K loading (3.5 wt%) favored C₅₊ hydrocarbon production, achieving a maximum STY of 632 g_fuelkg_cat⁻¹h⁻¹. Comprehensive characterization using XPS, Mössbauer spectra and in-situ DRIFT spectra revealed that K loading altering the chemical environment on the catalyst surface, thereby influencing the CO₂ hydrogenation pathway by balancing carbon chain growth and C-C coupling between oxygenated compounds. This study highlights the potential of K loading manipulation to precisely control product distribution in CO₂ hydrogenation, providing a viable pathway for optimizing catalyst performance for targeted chemical synthesis.