Effect of pre-treatment conditions on Fe-based catalyst for e-fuel production via modified Fischer-Tropsch synthesis

• Pre-treatment impacts Na-Fe 3 O 4 catalyst selectivity in CO 2 -to-liquids conversion. • Carburization at 400 °C promotes ε’-Fe 2.2 C formation, boosting C 5 + hydrocarbon yield. • Mössbauer and DHA with chemometrics clarify catalyst phases and product links. • Tailored pre-treatment guides optimal CO 2 conversion to sustainable liquid fuels. This work examines the influence of pre-treatment conditions on the Na/Fe 3 O 4 catalyst for CO 2 -modified Fischer-Tropsch synthesis (FTS) to optimize the conversion of CO 2 to liquid hydrocarbons. Using a synergy of Mössbauer spectroscopy, detailed hydrocarbon analysis (DHA) and chemometric analysis, the study identifies critical iron carbide phases formed under different pre-treatments and evaluates their influence on catalytic performance. Specific pre-treatments, notably carburization at 400 °C, were found to promote ε’- Fe 2.2 C formation, which enhanced C 5+ hydrocarbon selectivity, achieving yields between 14 % and 18 % and a balanced light-to-heavy oil ratio. In addition, the synergy of Mössbauer and DHA provided clear insights into phase composition and molecular distributions, enabling a more rigorous analysis of reaction pathways. These results underline the importance of tailored pre-treatment strategies for efficient CO 2 utilization, emphasizing the role of combined spectroscopic and chemometric approaches in advancing sustainable fuel synthesis. Overall, this work contributes to the understanding of catalyst behavior in CO 2 hydrogenation, highlighting the need for comprehensive liquid phase characterization to optimize catalytic processes for sustainable hydrocarbon production.