Densely embedded homogeneous FeOx nanoparticles in N-doped carbon frameworks: A 3D scaffold catalyst for high-temperature Fischer-Tropsch synthesis

Fe-based catalysts show great promise in advancing the application of high-temperature Fischer-Tropsch synthesis (HT-FTS) for producing value-added chemicals and liquid fuels; however, maintaining high catalytic activity and stability at elevated temperatures remains a significant challenge. Here, a novel approach was employed to prepare carbon sphere (CS)-supported Fe catalysts, where isolated Fe particles are efficiently embedded within a carbon matrix to enhance both catalytic activity and stability. The resulting 3D scaffold structure catalyst featuring ultrafine FeO x nanoparticles (NPs) dispersed within nitrogen-doped carbon frameworks was synthesized from Fe-chitosan/CS composites using a chelate-assisted impregnation method paired with unidirectional freeze treatment. The coordination between chitosan chains and Fe(Ⅲ) has yielded a homogeneous Fe-chitosan composite, with the embedded FeO x NPs within the nitrogen-doped carbon (NC) matrix serving as pivotal barriers against sintering, thus enhancing stability. The synergistic effect of adding K promoter and the resulting 3D scaffold structure in Fe-K@NC/CS catalyst has further fine-tuned catalytic activity, ensuring high stability in HT-FTS. The current strategy of fabricating N-doped 3D scaffold structures of hybrid carbonaceous material achieved unprecedented results, with the CO conversion reached 62.7 % and C 2 -C 4 = olefin selectivity of 29.0 % at 340 °C, 20 bar and space velocity of 48000 mL g cat –1 h −1 .