Fe-based catalyst for thermo-catalytic CO2 hydrogenation into ethanol: The essential role of water management and Fe-based carbide/oxide ratio

CO 2 hydrogenation to ethanol represents a pivotal pathway for valuable utilization of greenhouse gas CO 2 , yet conventional catalysts are still limited by active-phase instability and undesirable byproduct selectivity. Herein, we propose a dual-components catalyst system synergized by hydrophobic carbon-encapsulated Fe-based catalyst (NaFe@C) and K modified CuZnAl component (KCZA), which achieves ultra-high ethanol selectivity of 35% under optimized conditions (5 MPa and 320 °C). KCZA initiates the CO 2 activation via reverse water-gas shift reaction and supplies oxygen-containing intermediates (mainly CH x O*, x = 0, 1, or 2). NaFe@C component is mainly responsible for the C–O activation for CH x * formation and C–C coupling between CH x * and CH x O*, as well as the following hydrogenation step for ethanol synthesis. Notably, the hydrophobic carbon shell in NaFe@C plays a critical role in tailoring the oxidation behaviors of Fe-based active sites and optimizing the phase ratio of Fe 3 O 4 / χ -Fe 5 C 2 via water management. Multiple characterization and theoretical simulation results clarify that the unique electronic property of Fe-based active sites endowed by the optimized phase ratio is beneficial to boost the ethanol synthesis performance by balancing the coverage of key intermediates and lowering the energy barrier of essential steps. This work is promising to provide guidance for the rational design of advanced catalysts for targeted transformation of CO 2 or syngas into ethanol and beyond.