Hydrothermal carbon spheres with partially graphitized surfaces were investigated as potential candidates for catalyst support materials for FTS and resulted in high oxygenate formation when Co catalysts are used.  High CO conversion can be achieved, but is strongly dependent on the Co particle size on the carbon support, which in turn was greatly influenced by the different preparation methods used.  The CVD method led to the highest CO conversion (26.5%) while a more traditional, evaporative method (IWI) had significantly less CO conversion (7.4 %).  However, detailed microscopic investigations of the fresh catalysts and those after FTS for both preparation methods reveal that the original Co-particle arrangement on the carbon surfaces undergoes a change during the FT synthesis.  The carbon support structure was also altered during FTS . We believe that the extent of the changing support structure of the carbon spheres is, at least in part, caused by a selective breakdown of non-graphitized domains since the carbons were treated at 1900 o C which is well below the graphitization temperature.  The selectivity to olefins as a function of carbon number shows a difference for the two carbon supported catalysts; the one prepared with the CVD method has somewhat lower olefin selectivity and produced slightly lower alcohols. There seems to be a continual increase of oxygenated materials with TOS.  Both hydrothermal carbon-supported catalysts had high oxygenate- selectivity (10. 2% and 11%) and also produced a significant amount of olefins.

Fischer-Tropsch synthesis: High oxygenate selectivity of hydrothermal carbon supported cobalt catalysts

248th National Meeting (2014)

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