Role of the activation process on catalytic properties of iron supported catalyst in Fischer-Tropsch synthesis

Abstract

Monometallic Fe and bimetallic Ru–Fe supported catalysts were prepared by impregnation method and tested in Fischer-Tropsch synthesis (F-T). Their physicochemical properties were characterized by BET, SEM-EDS, FTIR, XRD, H2-TPR, TPD-NH3 techniques. The catalytic activity tests showed that the activation process has a huge impact on the reactivity properties in the studied process. The most active system in F-T reaction was 40%Fe/Al2O3–Cr2O3 catalyst which exhibited CO conversion equal 89.9% and the selectivity towards liquid product of 66.6%. The liquid products obtained in F-T process on 40%Fe/Al2O3–Cr2O3 consisted mainly of linear (76.8%), branched (17.7%) and unsaturated (5.5%) hydrocarbons. The chain growth probability in F-T process was estimated using an Anderson-Schulz–Flory distribution of obtained liquid product for all tested catalysts. The calculated α value for the most active catalyst was 0.76. The activity results indicate that iron carbides formed during activation process affects on the catalytic activity and selectivity of the iron catalyst during F-T synthesis. The activity measurements showed that the activity of the iron supported catalysts depends strongly on the catalyst phase composition and their acidic properties. XRD results confirmed that the most active catalyst in the investigated process exhibited the highest concentration of iron carbides phases on its surface.