From Nanoparticles to Process: An Aberration-Corrected TEM Study of Fischer-Tropsch Catalysts at Various Steps of the Process

Abstract:

χThe nanostructure of Fischer-Tropsch (FT) Fe carbides are investigated using aberration-corrected high-resolution transmission electron microscopy (TEM). The plasma-generated Fe carbides are analyzed just after synthesis, following reduction via a H2 treatment step and once used as FT catalyst and deactivated. The as-produced nanoparticles (NPs) are seen to be abundantly covered with graphitic and amorphous carbon. Using the extended information limit from the spherical aberration-corrected TEM, the NPs could be indexed as a mixture of NPs in the θ-Fe3C and χ–Fe₅C₂ phases. The reduction treatment exposed the NPs by removing most of the carbonaceous spe_{Subscript text}cies while retaining the χ–Fe₅C₂. Fe-carbides NPs submitted to conditions typical to FT synthesis develop a Fe₃O4 shell which eventually consumes the NPs up to a point where 3-4 nm residual carbide is left at the center of the particle. _{Subscript text}Various mechanisms explaining the formation of such a microstructure are discussed.

• Periodical: Advanced Materials Research (Volume 324)
• Pages: 197-200
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.324.197
• Online since: August 2011
• Authors: Nadi Braidy, Carmen Andrei, Jasmin Blanchard, Nicolas Abatzoglou
• Keywords: Aberration-Corrected TEM, Catalysis, Catalyst, EELS, Fe Carbides, Fe Oxides, Fischer-Tropsch Synthesis (FTS), Hägg Carbides, HREM

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