31P NMR MAS Spin-lattice relaxation as a dispersion probe: an easy access to active-site concentration in silica-supported dodecamolybdophosphoric acid

Abstract

Solid-state ³¹P spin-lattice relaxation of silica-supported dodecamolybdophosphoric acid dramatically depends on the polyanion : SiO₂ ratio for concentrations above that required for the saturation of the adsorption sites on the silica surface; this dependence allows the density of the active sites at the silica surface to be determined.