(106d) An Investigation Into the Role Played by the Initial Iron Oxide Phase In Determining Catalyst Performance

Iron-based Fisher-Tropsch (FeFT) catalysts have a number of characteristics that make them attractive in the Biomass to Liquids (BTL) arena.  Feedstock logistics dictate that BTL plants will be smaller than GTL and CTL plants. Furthermore, syngas obtained from biomass gasification typically have a H₂/CO ratio of 1 – 1.5.  Co-based FT catalysts require a H₂/CO ≥ 2 to prevent deactivation due to coke formation, thus requiring a separate WGS plant.  This may add cost and diminish the overall thermodynamic efficiency of the process.¹  Low Temperature FeFT (LT FeFT) catalysts are prepared by precipitation from a copper-containing iron nitrate solution, prepared by dissolving metallic copper and iron with concentrated nitric acid. The resulting precipitate is washed and promoters are added.  We have recently found that the mode of preparation exerts a significant influence on catalyst activity.²  In this paper, the relationship between observed synthesis results and different iron phases observed in fresh and spent catalyst, as determined by Mössbauer spectroscopy and XRD, is examined.

(1)           Bartholomew, C. H.; Hecker, W. C. Short Course on Fischer-Tropsch Catalysis: Fundamentals and Practice,  Brigham Young University, 2009.

(2)           Pretorius, P. J. Preparing low temperature iron Fischer-Tropsch catalysts: Strategies that work and those that do not., In 240^th ACS National Meeting Boston, MA, 2010.