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, H2-TPR, DR-UV–vis, XANES, EXAFS and the reactivity during Fischer–Tropsch synthesis (FTS) was tested at 230 °C, 5 bar with H2/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 C2–C4 paraffin products. The addition of 0.2 wt% Pd to 10Co-IP and 10Co-RM enhanced the cobalt reducibility, FTS 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 (C5–C9).
Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (284 K)Download as PowerPoint slideHighlight•Co/SiO2 from impregnation had larger particle size than from reverse micelle.•Catalysts were well characterized and tested for Fischer–Tropsch synthesis (FTS).•Catalysts from impregnation show better FTS performance than from reverse micelle.•Pd promoter lowers Co reduction temperature and acts as adsorption hydrogen sites.•0.2Pd-10Co-IP gave highest CO conversion and paraffins fraction in gasoline range.
Journal: Applied Catalysis A: General - Volumes 464–465, 15 August 2013, Pages 269–280