Synthesis, characterization, and catalytic properties of Ti, V, and Zr-HMSprepared by metallocene grafting

Ti, V, and Zr-HMS molecular sieves were prepared by grafting the respective metallocene onto the pure silica HMS. XRD, N-2-physisorption, TEM, UV-Vis spectroscopy and elemental analysis were performed to characterize the samp les prepared. The XRD patterns of the metal-grafted samples exhibited well- defined (100) reflections, and the intensity remained almost constant as wi th pure silica HMS. Surface area, hysteresis loop in N-2 adsorption isother ms and N-2 volume adsorbed decreased after metal grafting. The order of cat alytic activity for 2,6-di-tert-butylphenol (2,6-DTBP) oxidation using H2O2 was V-HMS (91.5 % conversion) much greater than Ti-HMS(20.3 %) > Zr-HMS(8. 4 %). Metal leaching was detected for all the grafted samples in the reacti on media; V-HMS(22 wt.%) much greater than Zr-HMS(3 wt.%) > Ti-HMS(2 wt.%). For V-HMS and Zr-HMS, further reaction after catalyst filtration indicated significant contribution to the reaction by the dissolved species.