Effect of activation atmosphere in the Fischer–Tropsch Synthesis using a “quasi-model” catalyst of γ-Fe2O3 nanoparticles supported on SBA-15

• Fe/SBA-15 was activated in H2 or syngas and used as Fischer–Tropsch catalyst.
• H2 activation leads to higher CO conversion and higher hydrocarbons production.
• H2 activation leads lower methane selectivity.
• Pre-synthesized γ-Fe2O3 nanoparticles were used to obtain a “tailored” catalyst.

The effect of different activation atmospheres (CO:H2 or pure H2) on activity and selectivity of iron nanoparticles supported on SBA-15 in Fischer–Tropsch Synthesis, has been studied. To achieve this aim a new preparation method, using monodisperse pre-synthesized γ-Fe2O3 nanoparticles of 3 nm size, supported on SBA-15, was used. These catalysts have structural properties between real and model catalysts. Therefore, they were named “quasi-model” catalysts. Nanoparticles and catalysts were characterized with several techniques: XRD, N2 adsorption at 77 K, magnetic measurements, electron transmission microscopy, Mössbauer spectroscopy between 298 and 13 K in air and controlled atmosphere and thermal gravimetric analysis. Catalytic tests showed clearly that activation with pure H2 leads to a catalyst more active and less selective to methane than that activated with CO:H2. To explain these results, different reduction steps were proposed. These different sequences would produce a diverse number of active sites.

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