(440f) Development of FeCo Catalysts Supported on TiO2 Nanotube Arrays Grown on 3D-Printed Structures: Applications in Fischer-Tropsch Synthesis

Fischer-Tropsch Synthesis (FTS) is a prominent reaction for converting synthesis gas (syngas) into high-value liquid chemicals and fuels. Syngas is derived from the thermal conversion of coal, but it can also be obtained from biomass and natural gas. FTS yields olefins, paraffins, and oxygenated molecules (alcohols and carbonyls) via a series of surface polymerization reactions. However, its optimization remains challenging due to its complexity and dependence on process parameters, including temperature, pressure, residence time, and catalyst type. The support material in an FTS catalyst dictates CO conversion and C₅₊ selectivity, with TiO₂ remaining a popular option due to its abundance and desirable material properties. The development of state-of-the-art technologies in materials science further propels efforts to enhance TiO₂'s functionality as a support. Additive manufacturing (3D printing) has gained prominence in the manufacturing of metal components due to its versatility and reduction of energy consumption.

In this contribution, 3D-printed Ti-6Al-4V structures are used as catalytic support substrates for developing superficial TiO₂ nanotube arrays (TNAs). This architecture is hypothesized to be desirable because it facilitates molecular diffusion and minimizes the complexity of its porous structure. These nanostructures are optimized by annealing, with crystal structure, morphology, and elemental composition changes evaluated via FESEM, XRF, XRD, and EDXS. Bimetallic catalysts are then synthesized by impregnating the TNAs with iron (Fe)-cobalt (Co) nanoparticles, and their activity is tested for FTS at 250 °C. The results show that the optimal sequence for the synthesis of TNAs involves a two-step electrochemical anodization in ammonium fluoride (NH₄F), followed by low-temperature annealing at 450 °C. The resulting catalysts are active for FTS, displaying a rate of CO consumption of 2.43 x 10^-5 ± 8.99 x 10^-6 mol_CO/s·g_FeCoand a chain growth probability (α) of 0.273 ± 0.143.