TiO_2 Nanoparticles in Mesoporous TUD-1: Synthesis,Characterization and Photocatalytic Performance in Propane Oxidation

摘要

A series of TiO_2-TUD-l samples was synthesized with a variable Ti loading in the range Si/Ti = 100,20,2.5,and 1.6,by using a one-pot surfactant-free procedure.The materials obtained were characterized by elemental analysis;X-ray diffraction (XRD);N_2 sorp-tion measurements;high-resolution TEM (HR-TEM);~(29)Si NMR,UV-visible and Raman spectroscopy.As a function of increasing metal loading either isolated Ti atoms,or (above a Ti loading of -2.5 wt-%) combinations of isolated Ti atoms and anatase (TiO_2) nanoparticles were obtained;both were incorporated in the highly porous siliceous matrix.The photocatalytic performance of these materials was tested by studying the propane oxidation process following irradiation at lambda = 365 nm,selectively activating the anatase nanoparticles.In comparison to commercial anatase powder,TiO_2 nanoparticles in TUD-1 showed high photochemical selectivity towards acetone,the sample with a Si/Ti ratio of 1.6 being the most selective.Size and confinement effects are consistent with the difference in performance of the TUD-1 materials and TiO_2,limiting the number of electron transfers available for each propane molecule.