(351b) An Fe/Cu/K/SiO2 Fischer-Tropsch Catalyst Prepared by Solvent-Deficient Co-Precipitation

A novel catalyst preparation method in which reactants are not dissolved in solvent prior to reaction has been developed for Fe/Cu/K/SiO2 Fischer-Tropsch catalysts. The solvent-deficient method is simpler, faster, requires fewer preparation steps, and uses less water than more standard co-precipitation methods. This promising preparation method produces uniform crystallite sizes between 2 and 4 nanometers or 15 and 30 nanometers, depending on the drying step. XRD analysis shows that the precipitated precursor is consistent with 2-line ferrihydrite. BET surface area analysis gives calcined surface areas between 200 and 300 m2/g and reduced/passivated surface areas between 90 and 120 m2/g. Pore volumes are between 0.19 and 0.29 mL/g and 0.14 and 0.15 mL/g for calcined and reduced catalysts, respectively. H2 uptake measurements on reduced catalysts are 151 to 160 micromol/g. Activity at 260°C, 20 atm, and a H2:CO ratio of 1 was very high with a turnover frequency of 0.028 1/s. For comparison, catalysts of the same composition were prepared using the more common co-precipitation method. Surface areas, pore volumes, H2 uptakes, and activities were very similar for catalysts made using the solvent-deficient and standard co-precipitation methods. Comparisons to published studies (Bukur et. al. and Wu et. al. [1-3]) show that the solvent deficient method produces similar reduced surface areas, H2 uptakes, and promising selectivities and activities, though activity studies were done at different conditions. Further work will be done to determine the stability and activity of the solvent-deficient catalysts at published conditions for a more direct comparison. The solvent-deficient method produces active and selective catalysts comparable to other published iron Fischer-Tropsch catalysts at a fraction of the time, setup, and water necessary for standard co-precipitation preparations.

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