(544bd) Carbon Sphere Supported Cobalt Catalysts for Fischer Tropsch Synthesis
This work examines the metal-support interactions of cobalt supported carbon spheres catalysts. These carbon spheres were produced by two methods (i) the chemical vapour deposition method using acetylene as the carbon source (CVD) and (ii) the hydrothermal decomposition of sucrose (HDS). The carbon spheres produced have different surface properties and were used as supports for 5 % cobalt FT catalysts. It was found that the CSs produced were thermally stable to 560 oC and are purely carbonaceous materials (C > 95%). The porosity and surface area of the HDS carbon spheres was controllable by heat treatment while the CVD carbon spheres are non-porous. The effect of functionalising agents (KMnO4 and HNO3) on the surface properties of carbon spheres was also investigated. Functional groups (-OH, -COOH, etc) introduced on CSs were characterised by FTIR spectroscopy, alkalimetry and TGA. These functionalised CSs were also investigated as supports for 5 % cobalt catalysts. The presence of manganese species from KMnO4 embedded in the CS support materialwas found to inhibit cobalt catalysed hydrogenation reactions. Furthermore it was found that manganese oxide species are closely associated with FT active Co0 sites and increased C5+ and olefin product selectivity.