Study of the effect of cobalt content in obtaining olefins and paraffins using the Fischer-Tropsch reaction

This work presents the synthesis, characterization and testing of catalysts for the Fischer-Tropsch reaction. Molecular sieve MCM-41 was prepared under hydrothermal treatment at 150 °C for 2 days, using the following molar composition of reagents: 1 SiO2:0.27 CTABr:0.19 TMAOH:40 H2O. Obtaining the mesoporous molecular sieve, Si-MCM-41, was confirmed by X-ray diffraction. The deposition of cobalt on MCM-41 support was carried out by wet impregnation, using an aqueous solution of cobalt nitrate. The images obtained from TEM clearly showed a good dispersion of the cobalt on the support (MCM-41). The textural characteristics of the samples were investigated by isothermal gas adsorption/desorption. Using the BJH method, it was possible to obtain the values of the average pore diameter on adsorption and desorption. The obtained catalysts containing different cobalt concentrations were evaluated for the Fischer-Tropsch reaction. Increasing the temperature increases the selectivity to olefins with the 15 wt.% Co/MCM-41 catalyst, as well as increases the selectivity to methane with the 5 wt.% Co/MCM-41 catalyst.

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► Molecular sieve MCM-41 was prepared under hydrothermal treatment.
► Cobalt was deposited on MCM-41 support by wet impregnation.
► The catalysts were evaluated for the Fischer-Tropsch reaction.
► The cobalt content and temperature influence the selectivity.
► The catalyst 15 wt.% Co/MCM-41 presents the highest selectivity to paraffin.