| Popis: |
The location and distribution of reduction promoters (Ir, Pt, Re, Ru) in reduced & passivated cobalt Fischer-Tropsch catalysts were investigated using an aberration-corrected Scanning Transmission Electron Microscope, SuperSTEM, located at Daresbury, UK. This instrument has better than 0.1 nm resolution. Atomic number contrast imaging is achieved using a high-angle annular dark-field detector (HAADF) and elemental spectroscopy with close to 0.1 nm spatial resolution with electron energy-loss spectroscopy (EELS). The results showed Re, Pt and Ir reduction promoters mainly as isolated atoms whereas Ru was present both as isolated atoms and regions of high concentration within Co particles and, occasionally, as separate particles. |
