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Fischer-Tropsch synthesis is a catalytic process to produce hydrocarbons from a syngas, which could come from biomass. It is therefore an alternative process to help reduce the share of oil in the energy mix and IFPEN is seeking to optimize its performance, in particular by improving the catalysts used.

One of the main challenges to overcome is to relate the performance (activity, selectivity) of these catalysts, containing cobalt nanoparticles, to the properties of the metal phase. To achieve this, a good multiscale description of these catalysts is essential.

To this end, a methodology has been developed to obtain an original description of cobalt nanoparticles1. It employs two cutting-edge techniques:

  • electron tomography, which provides 3D visualization of cobalt aggregates (figure) on a nanometric scale, emphasizes, in particular, their different structures depending on the catalyst’s state (oxidized or reduced);
      
  • anomalous small angle X-ray scattering (ASAXS), performed on the SWING beamline of the synchrotron SOLEIL, which enables to characterize the distribution of cobalt, via the size distribution of the particles and aggregates. The results obtained have confirmed the observations made by electron tomography, i.e. a better dispersion of cobalt after the reduction step.

 

Reconstruction 3D d’un agrégat de cobalt (réduit) obtenu par tomographie électronique.
3D vizualisation of a (reduced) cobalt aggregate obtained by electron tomography.

 

This methodology allows to characterize catalysts at different scales and in all the states encountered during their lifecycle (oxidized, activated, spent).

The results obtained will help provide a better understanding of:

  • the influence of preparation conditions on the properties of the active phase, 
     
  • and the relationship between these morphological properties and catalytic performance.

 


(1)  S. Humbert, A.-S. Gay, A.-L. Taleb, V. Lefebvre, C. Dalverny, G. Desjouis, A. Berliet, T. Bizien. Research pending publication.

 


Scientific contacts: severine.humbert@ifpen.fr - anne-sophie.gay@ifpen.fr

>> ISSUE 28 OF SCIENCE@IFPEN