Popis: |
Phosphate species deposited on titanium silicalite (TS-1) can interfere with epoxidation by hydrogen peroxide. Phosphates grafted on TS-1 are identified by solid-state31P MAS NMR. Signals at −5.1, −10.8 and −20 ppm are attributed to monodentate, chelating or bridging phosphate ions and polyphosphates, respectively. Phosphate-modified TS-1 can anchor tungsten oxoperoxo species; with aqueous hydrogen peroxide, this novel class of supported catalysts can oxidize bulky molecules under mild conditions. |