Transitional metal (Cu, Mn and Zn) containing Co-Fe tri-metallic catalysts [Co0.7Cu0.3Fe2.0, Co0.7Mn0.3Fe2.0, Co0.7Zn0.3Fe2.0, Co1.0Fe2.0] were prepared to be used in Fischer-Tropsch synthesis (FTS). The role of Cu, Mn and Zn on the rate of carburization of Co-Fe catalysts and how does it affects the stability of iron carbides during FT synthesis was studied. A novel oxalate co-precipitation and decomposition method was used to obtain the catalyst precursor in Cobalt Ferrite form (Co0.7M0.3Fe2O4, where M=Cu, Mn, Zn). The precursor (cobalt Ferrite) obtained was further pretreated in the CO flow at 270°C and 170 psig which forms iron carbides (χ-Fe5C2 and ε-Fe2.2C) in addition to a bimetallic Co-Fe. The precursors and the catalysts before and after the reaction are studied by means of X-ray diffraction (XRD), Mössbauer Spectroscopy, X-ray Absorption Spectroscopy (XAS), X-ray Photoelectron Spectroscopy (XPS) and High Resolution Transmission Electron Microscopy (HR-TEM) techniques. There is a slight decrease in the total iron carbides formed after the addition of Cu to cobalt ferrite under similar activation conditions. A significant decrease in the formation of iron carbide is observed with the addition of Mn to cobalt ferrite, likewise Zn severely limits the conversion of cobalt ferrite to iron carbide during CO activation. Both updoped and Cu-doped cobalt ferrite exhibit much higher CO converion in comparison with Mn and Zn doped catalysts under the similar reaction conditions. The addition of Cu promotes alcohol formation from syngas whereas Mn increased olefinic products selectivity of Co-Fe catalyst.

Fischer-Tropsch synthesis: Effect of Cu, Mn, and Zn addition on the activity and product selectivity of cobalt ferrite catalyst

251st National Meeting (2016)

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