Catalysis Letters, Vol.25, No.3-4, 225-240, 1994
On the Physicochemical and Catalytic Properties of H5Pv2Mo10O40 Supported on Silica
Properties of H5PV2Mo10O40 (HPVMo) heteropolyacid supported on high area silica (375 m2 g-1) were investigated. At low loadings interaction with surface OH groups leads to hydrolysis of Keggin anions into "triads" of edge-sharing octahedra strongly bound to the surface. Characteristic acidity is lost and methanol is oxidized to formaldehyde. At high loading unperturbed Keggin anions are present at the surface. Properties resemble those of unsupported acid. Thermally decomposed Keggin anions become reconstructed under exposure to water vapor. Dimethylether is mainly formed from methanol.
Keywords:H3+N(PVNMO12-NO40).XH2O(N = 0;ELECTRON-SPIN RESONANCE;12-MOLYBDOPHOSPHORIC ACID;HETEROPOLY ACIDS;LASER RAMAN;H3+NPVNMO12-NO40 HETEROPOLYACIDS;THERMAL-DECOMPOSITION;12-HETEROPOLY ACIDS;MOLYBDENUM TRIOXIDE;OXIDATION