Keggin-type polyacid clusters on apatite: characteristic catalytic activities in solvent-free oxidation
摘要:
We found that Keggin-type phosphometalates are effective catalysts for solvent-free oxidation With urea-H2O2 by dispersing on fluorapatite solid phase. In the solid phase system the phosphomolybdate (NH4)(3)PMo12O40 was more effective than the phosphotungstate (NH4)(3)PW12O40, whereas the latter was much superior to the former in the liquid-phase reaction with aqueous H2O2. In situ formation of novel peroxo-type species from (NH4)(3)PMo12O40/FAp and urea-H2O2 which may lead to the high catalytic activity in the solid phase system, was observed by P-31 solid-state NMR. (C) 2002 Published by Elsevier Science Ltd.