Effect of Fe on Co-Based SiO2Al2O3 Mixed Support Catalyst for Fischer–Tropsch Synthesis in 3D-Printed SS Microchannel Microreactor

This research explores the effect of a composite support of SiO₂ and Al₂O₃ with Fe and Co incorporated as catalysts for Fischer-Tropsch synthesis (FTS) using a 3D-printed stainless steel (SS) microchannel microreactor. Two mesoporous catalysts, FeCo/SiO₂Al₂O₃ and Co/SiO₂Al₂O₃, were synthesized via a one-pot (OP) method and extensively characterized using N₂ physisorption, XRD, SEM, TEM, H₂-TPR, TGA-DSC, FTIR, and XPS. H₂-TPR results revealed that the synthesis method significantly affected the reducibility of metal oxides, thereby influencing the formation of active FTS sites. SEM-EDS and TEM further revealed a well-defined hexagonal matrix with a porous surface morphology and uniform metal ion distribution. FTS reactions, carried out in the 200-350 °C temperature range at 20 bar with a H₂/CO molar ratio of 2:1, exhibited the highest activity for FeCo/SiO₂Al₂O₃, with up to 80% CO conversion. Long-term stability was evaluated by monitoring the catalyst performance for 30 h on stream at 320 °C under identical reaction conditions. The catalyst was initially active for the methanation reaction for up to 15 h, after which the selectivity for CH₄ declined. Correspondingly, the C₄⁺ selectivity increased after 15 h of time-on-stream, indicating a shift in the product distribution toward longer-chain hydrocarbons. This trend suggests that the catalyst undergoes gradual activation or restructuring under reaction conditions, which enhances chain growth over time. The increase in C₄⁺ products may be attributed to the stabilization of the active sites and suppression of methane or light hydrocarbon formation.