Abstract
A series of redox mesopore molecular sieves Ti-, V-, Zr- and Mo-MCM-48 were prepared by grafting the respective metallocene onto the MCM-48 host. XRD, TEM, and BET analysis of the transition metal substituted MCM-48 indicated that high crystallinity and pore structure were maintained after grafting. Grafting of the transition metal species to MCM-48 structure was confirmed by IR and UV–vis spectroscopy. The metallocene grafted MCM-48 samples were active for liquid phase oxidation of the bulky 2,6-di-tert-butyl phenol (2,6-DTBP) with aqueous H 2O 2. For a given metallocene concentration in grafting solutions, Mo was the least grafted element to MCM-48 surface, but its catalytic activity was superior either to Ti- or Zr-grafted MCM-48. V-MCM-48 showed the highest catalytic activity. Chemical analysis of the mother liquor after reaction, however, showed substantial leaching for Mo and V. Ti and Zr also suffered mild leaching. Further silylation treatment to Ti- and V-MCM-48 could not prevent leaching. Activity for 2,6 DTBP oxidation deteriorated significantly upon silylation for Ti-MCM-48.
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