Structure and photocatalytic activity studies of TiO2-supported over Ce-modified Al-MCM-41

Ce-Al-MCM-41, TiO2/Al-MCM-41 and TiO2/Ce-Al-MCM-41 materials with varying contents of Ce (by impregnation) and TiO2 loaded (by solid-state dispersion) on Al-MCM-41 support are prepared. The Ce modified and TiO2 loaded composite systems are characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UV-vis diffuse reflectance spectra (DRS) and X-ray photoelectron spectroscopy (XPS) techniques. The DRS and XPS of low Ce content (0.2-0.5 wt.%) modified Al-MCM-41 samples are showing more characteristic of Ce3+ species wherein cerium in interaction with Al-MCM-41 and that of high Ce (0.8, 3.0 wt.%) content modified samples are showing the characteristic of both Ce4+and Ce3+species. A series of Ce-modified Al-MCM-41 and TiO2 loaded composite catalysts are evaluated for photocatalytic degradation of phenol under UV irradiation. Low Ce content in Ce3+ state on Al-MCM-41 is showing good photoactivity in comparison with high Ce content samples and pure ceria. The composite TiO2/Ce-Al-MCM-41 is showing enhanced degradation activity due decreased rate of electron-hole recombination on TiO2 surface by the redox properties of cerium. The photocatalyst TiO2/Ce-Al-MCM-41 with an optimum of 10 wt.% TiO2 and 0.3 wt.% Ce is showing maximum phenol degradation activity. The possible mechanism of phenol degradation on the composite photocatalyst is proposed.