(643g) Novel Cobalt Catalyst Supported On Titania-Decorated Silicon Carbide for Fischer-Tropsch Synthesis

The interactions between cobalt nanoparticles and a TiO₂-decorated silicon carbide (β-SiC) support were explored by a combination of energy-filtered transmission electron microscopy (EFTEM), ⁵⁹Co zero-field nuclear magnetic resonance (⁵⁹Co NMR), and other conventional characterization techniques. From 2D elemental maps deduced by 2D EFTEM and ⁵⁹Co NMR analyses it was observed that nanoscale introduction of TiO₂ into the β-SiC matrix significantly enhanced the formation of small and medium-sized cobalt particles active for Fischer-Tropsch synthesis. The results obtained revealed that adequate interactions between cobalt nanoparticles and TiO₂ led to the formation of smaller cobalt particles (<15 nm), which possess a large fraction of surface atoms and, thus, significantly contribute to the enhancement of conversion and reaction rate. The cobalt time yield of the catalyst after modification increased to 7.5 × 10⁻⁵ mol_CO g_Co s⁻¹ at 230 °C, whereas the C₅₊ selectivity was maintained a high level (>90%). In addition, the distribution of meso- and macro-pores in the SiC-based support facilitated intimate contact between reactants and active sites and accelerated the evacuation of the products of reaction. A stable FTS specific rate of 0.56 g C⁵⁺ g_catalyst⁻¹ h⁻¹ together with a high C₅₊ selectivity of 91% were obtained with a 30 wt % cobalt loading.