Iron Oxide Nanoparticles as Fischer-Tropsch Synthesis Catalysts in Fixed Bed Reactors

Iron oxide nanoparticles (α-Fe2O3, 20-50 nm) have been evaluated as catalysts in Fischer-Tropsch Synthesis in a fixed bed reactor. XRD, BET and SEM analyses were performed on fresh nanopowders and nanocatalyst to investigate the preparation method effect on catalyst activity. Activity and selectivity of this catalyst were determined at a constant pressure of 20 bar. To optimize the operating conditions of FTS, Taguchi experimental design method has been implemented. The effect of three pertinent factors has been considered: temperature, inlet H2/CO molar ratio and syngas space velocity. Experiments were carried out under a wide range of conditions including reaction temperature of 260-300 °C, inlet H2/CO molar ratio of 0.67-2.00 and space velocity of 3-15 NL gFe-1h-1. The rate of formation of heavier hydrocarbons (C5+) as a function of CO consumption has been chosen as the response of the system. The results from statistical design showed that the optimum conditions were: reaction temperature: 260 °C, inlet H2/CO molar ratio: 0.67, syngas space velocity: 3 NL g Fe-1h-1. Under these conditions, the rate of formation of C5+ versus CO consumption was 35.5948 g/g cat. mol CO consumed. Growth probability of hydrocarbons (α) was taken as a basis for comparing the performance of several iron nanocatalysts (NANOCAT, 3nm and BASF, 20-80nm) and industrial UCI catalyst applied in the slurry phase FT process with the present iron nanocatalyst. Results indicated that iron oxide nanoparticle applied in a fixed bed reactor exhibits a higher activity in hydrocarbon chain growth in comparison with those applied in a slurry phase FT process.