Palladium-promoted cobalt catalysts supported on silica prepared by impregnation and reverse micelle for Fischer-Tropsch synthesis

The objectives of this work were to compare physicochemical properties of silica-supported cobalt catalysts (with 10 wt% Co) prepared by impregnation (10Co-IP) and precipitation using a reverse micelle technique (10Co-RM) and to investigate influence of palladium as a promoter (0.2 wt% and 1.0 wt%) on properties of 10Co-IP and 10Co-RM. The catalysts were characterized by XRD, H-2-TPR, DR-UV-vis, XANES, EXAFS and the reactivity during Fischer-Tropsch synthesis (FITS) was tested at 230 degrees C, 5 bar with H-2/CO = 2. The particle size of Co3O4 in 10Co-IP was larger than that of 10Co-RM which could contribute to lower selectivity to methane and C-2-C-4 paraffin products. The addition of 0.2 wt% Pd to 10Co-IP and 10Co-RM enhanced the cobalt reducibility, FITS activity and paraffin selectivity. On the other hand, the addition of 1.0 wt% Pd resulted in increased methane formation and lower CO conversion. The most suitable catalyst from this work was 0.2Pd-10Co-IP that gave high CO conversion (34.8%) and high mole fraction of paraffins (0.38) in the gasoline range (C-5-C-9). (C) 2013 Elsevier B.V. All rights reserved.