Catalysis Letters, Vol.41, No.3-4, 153-157, 1996
O-17 MAS NMR-Study of 12-Molybdophosphoric Acid
O-17 MAS NMR spectra for O-17 enriched solid heteropoly acid H3PMo12O40 are reported. The oxygen exchange between solid (H3PMo12O40)-O-17 and (H2O)-O-16 vapor at 200-250 degrees is shown to be accompanied by fast mixing of terminal Mo=O and bridging Mo-O-Mo oxygens in the Keggin unit. The oxygen exchange in (H3PMo12O40)-O-17 is much faster than in (H3PW12O40)-O-17 in solution as well as in the gas phase.
Keywords:SOLID-STATE NMR;PROTON SITES;HETEROPOLYACID H3PW12O40;P-31;CATALYSIS;OXIDATION;SILICA;KEGGIN;SIO2;H-1