Jornal de termodinâmica e catálise
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Catalyst and Catalysis for Fischer-Tropsch Synthesis: A Comparative Analysis of Iron and Cobalt Catalysts on SBA-15

Mala A Sainna and Abba MK

The influence of Cobalt and iron loading, cobalt and iron precursor, and the effect of promoters(Mg and Mn) on the physico-chemical properties as well as the catalytic properties and structural appearance of mesopourous Co/ SBA-15, Fe/SBA-15 and bimetallic Fe, Co/SBA-15 catalysts for Fischer-Tropsch (FTS) reaction is investigated. The various prepared catalysts were characterized by X-ray diffraction (XRD), scanning electron micropscope (SEM), Energy dispersion X-ray diffraction (EDX) and Temperature programmed reduction (TPR). For the Co/SBA-15 and Fe/SBA-15 prepared and promoted with Magnesium and manganese (Mg, Mn), the dispersion of the metal loaded (Fe, Co) increases significantly when compared to the un-promoted Co/SBA-15 and Fe/SBA-15, and the dispersion of metal loaded (Co, Fe) was found to be higher with Mg than Mn promoter. The bimetallic catalyst was also found to have a higher dispersion of the metals than a single metal loaded catalyst (Co/SBA-15, Fe/SBA-15). Promoting the catalyst with Mn increases dispersion but it was said to decrease reducibility leading to a catalyst that is less reactive than the un-promoted one [1-3]. The mesopourous catalyst prepared did not show any crystal growth in their meso-channels which propose the dispersion of the active metals on the mesopore and the formation of tiny crystals (nanocrystal) undetectable by the X-ray diffractogram. The absence of an intense peak of the crystals (Co3O4, Fe3O4) at an expected angle might be due to the existence of ions of cobalt and iron which might be existing as a nanocluster or due to the disintegration of the mesopores structures.