Effect of niobium promoter on iron-based catalyst for Fischer-Tropsch reaction

Niobium-promoted Fe/CNTs catalysts were prepared using a wet impregnation method. Samples were characterized by nitrogen adsorption, H₂-TPR, TPD, XRD and TEM. The Fischer-Tropsch Synthesis (FTS) was carried out in a fixed-bed microreactor at 220 ℃, 1 atm and H₂/CO=2 for 5 h. Addition of niobium into Fe/CNTs increased the dispersion, decreased the average size of iron oxide nanoparticles and the catalyst reducibility. Niobium-promoted Fe catalyst resulted in appreciable increase in the selectivity of C₅₊ hydrocarbons and suppressed methane formation. These effects were more pronounced for the 0.04%Nb/Fe/CNTs catalyst, compared to those observed from other niobium compositions. The 0.04%Nb/Fe/CNTs catalyst enhanced the C₅₊ hydrocarbons selectivity by a factor of 67.5% and reduced the methane selectivity by a factor of 59.2%.