Biosyngas conversion by Fischer-Tropsch synthesis : experimental results and multi-scale simulation of a PBR with high Fe loaded supported catalysts

Bio-syngas, i.e. the syngas mixture produced from biomass, is mainly characterized from a H2/CO molar ratio in the range 1.0-1.5, different from those of traditional syngas equal to 2. By feeding directly this mixture in a catalytic reactor for Fischer-Tropsch synthesis, iron based catalysts are more suitable with respect to the cobalt-based one. These catalysts are used industrially in their massive form. The possibility to use supported Fe-based catalysts are recently deeply considered in order to improve the surface area and the mechanical stability of the samples. In particular high Fe loaded supported catalysts are required to achieve satisfactory performance. Iron-based catalysts supported on silica for CO hydrogenation with 30%wt of metal have been prepared, characterized by BET, SEM, TEM, TPR, XRD and tested at different temperature and H2/CO ratio in a FT laboratory plant using a Packed Bed Reactor. On the basis of the collected data, a multi-scale simulation of the FT synthesis reactor has been developed considering that on the catalyst surface the reaction both of FT and Water Gas Shift are simultaneously activated. The experimental results demonstrated that by increasing the inlet H2/CO ratio, the CO conversion can be increased while preserving the products selectivity and confirm that FT are suitable also for low H2/CO ratio; furthermore the model elaborated agree with the experimental data obtained.