The growing need for non-petroleum based fuel sources has led to an increase in research into Fischer-Tropsch synthesis (FTS), which can be used to convert biomass into fuels. We have developed several silica supported cobalt catalysts to investigate the role of pore size on phase and reactivity. Cobalt based catalysts produce high molecular weight hydrocarbons in FTS, and there has been increased research into the characterization of such catalysts. The catalysts have been previously characterized using several techniques including x-ray diffraction (XRD), nitrogen porosimetry, and transmission electron microscopy/selected area diffraction (Ghampson IT, et al. Effects of pore diameter on particle size, phase, and turnover frequency in mesoporous silica supported cobalt Fischer-Tropsch catalysts. Applied Catalysis A – General. 2010; 388(1-2)).

 

In this presentation we will discuss x-ray absorption near edge structure (XANES) and extended x-ray absorption fine structure (EXAFS) measurements of three different MCM-41 supported cobalt catalysts. These materials include incorporation of cobalt into the silica framework (Co-MCM-41), and cobalt impregnated catalysts, via wet impregnation, onto the pure (Co/MCM-41) and cobalt in the framework (Co/Co-MCM-41) supports. We analyzed the XANES and EXAFS at three different stages in the catalyst history: after calcination, after temperature programmed reduction, and after Fischer-Tropsch synthesis. Evidence suggests that the presence of cobalt in the framework affects the reducibility of the cobalt species. The data also suggests mixed phases of cobalt metal and cobalt monoxide in the reduced and post FTS samples. The as prepared samples show only the Co3O4 phase, while the post FT and post TPR show both CoO and Co metal. The good agreement between XAS and XRD measurements demonstrates the use of these techniques to quantitatively determine the cobalt phase composition.