The role of Na for efficient CO2 hydrogenation to higher hydrocarbons over Fe-based catalysts under externally forced dynamic conditions

Considering the on-going developments of approaches for CO2 capture, storage, and utilization, CO2 hydrogenation with renewable H2 can become sustainable technology to produce value-added chemicals/fuels in future feedstock scenarios. Herein, we investigate temporal behaviors of Fe-based catalysts in CO2 hydrogenation under externally forced dynamics of reactor operation from the respective of composition and performance. Different catalyst preparation methods were applied to modulate the surface concentration of Na promoter but keeping the bulk concentration constant. The crucial promoter role in reserving catalyst performance and (un)steady-state catalyst composition during dynamic reactor operation was investigated by means of sophisticated catalytic tests combined with in situ and ex situ catalyst characterizations. The surface Na/Fe ratio of spent catalysts was identified as the decisive descriptor for production of the desired products under dynamic CO2 hydrogenation conditions. The derived knowledge could be useful for redesigning catalysts and optimizing reaction processes when employing fluctuating energy supply.