Na Promoter Synergistic Tuning Co-Fe Alloy-Carbide Dual Sites: Directing Syngas Conversion to C2+ Alcohols
Direct conversion of syngas to higher alcohols (C2+ alcohols) is critical for coal-based resource utilization and energy security. Here, a series of Na-modified CoFe/Al2O3 catalysts were synthesized via incipient wetness impregnation and evaluated for syngas-to-alcohol reactions. Multiple characterizations (XRD, N2 adsorption-desorption, H2-TPR, XPS, DRIFTS, in situ Raman, Mössbauer spectroscopy) elucidated synergistic effects of Na and Fe promoters. Na facilitated formation of Co-Fe alloy sites during reaction, while Fe modified electronic state of Co and promoted transformation of lattice oxygen to adsorbed oxygen, increasing surface oxygen vacancies. Synergistic interaction between alloy and carbide sites enhanced CO insertion into olefin intermediates, improving C2+ alcohol selectivity. Under 260 °C and 2 MPa, Co1Fe1Na1 catalyst (n(Co):n(Fe):n(Na)=1:1:1) achieved total alcohol selectivity of 45%, with C2+ alcohols comprising 94.1% of total alcohols. This study provides insights into rational design of Co-based catalysts for efficient syngas conversion to C2+ alcohols.