Modeling the Intensified Fischer–Tropsch Synthesis for Localized Production of Liquid Fuels in Multiphase Packed-Bed Microreactors

Intensifying Fischer–Tropsch (FT) synthesis with microreactors is a key strategy for new applications by enabling smaller, more efficient plants that can operate in new windows, such as localized production of liquid fuels and chemicals in offshore environments or from decentralized syngas sources such as biomass or waste. This approach was analyzed in multiphase packed-bed microreactors (PBMRs), ideal for FT synthesis offering higher volumetric productivity via a 3D Eulerian framework to simulate the complex two-phase flow coupled with species transport equations in bulk gas/liquid phases and continuity equations for internal diffusion and chemical reactions within the catalyst particles. The results showed that the intensification of FT synthesis in multiphase PBMRs with high surface-to-volume ratios provides a superior alternative to conventional trickle-bed reactors, offering enhanced mass transfer, superior wetting, and higher CO/H2 conversion. Moreover, FT synthesis in PBMRs enables operation at lower pressures and higher efficiencies than in traditional reactors because the smaller catalysts improve mass transfer, reducing diffusional resistance (higher effectiveness factors). Co/MnO catalyst outperforms Co/MgO in intensified PBMRs due to synergistic electronic and structural promotion of manganese, which facilitates better CO/H2 interaction, increased CO dissociation, and enhanced chain growth, leading to higher conversions and efficient hydrocarbon production. Operating with larger particles and lower gas velocities in micropacked beds reduces pressure drop by lowering the flow resistance. Additionally, lower gas and liquid flow rates in FT synthesis ensure efficient direct gas–solid contact for efficient mass transfer, which is essential for efficient product formation. By controlling these rates, pressure-drop issues across the catalyst bed are mitigated without sacrificing performance, contributing to process intensification in multiphasic microreactors.