Carbon-13 NMR spectra of carbon-13 monoxide adsorbed on silica-supported palladium particles: particle size dependence of the surface diffusion rate and the carbon-13 Knight shift

摘要: The {sup 13}C NMR spectra of 13}CO adsorbed on a 56% dispersion silica-supported Pd catalyst are found to be quite different from those reported for 19% catalyst. mobility the is greatly reduced these small particles, which interpreted as consequence increase in relative number low-coordination, electron-deficient sites such edges and corners concomitant tendency CO bind there linear fashion. This supported by observation that this has very little Knight shift due decrease local electron density at Fermi level sites, while bridging terraces still substantially shifted. Comparison FTIR shows extinction coefficient approximately half CO. These results correlate well with previous work dependence magnetic susceptibility particles IR catalysts.