Influence of titania content on the mesostructure of titania–silica composites and their photocatalytic activity

Fabrication of spent FCC catalyst composites by loaded V2O5 and TiO2 and their comparative photocatalytic activities

The spent fluid catalytic cracking catalyst (FCC) has been loaded with different content of V₂O₅ and TiO₂ through a modified-impregnation method. X-ray Diffraction (XRD), ultraviolet-visible spectrophotometry (UV-Vis), Scanning Electron Microscope (SEM), and Fourier Transform Infrared spectroscopy (FT-IR) are used to characterize the structure and morphology of these samples. Their photocatalytic activity was evaluated by degradation of methylene blue (MB) solution under 300 W Xenon lamp irradiation. The interplanar spacing of the zeolite Y (111) plane is affected by the amount of the loaded V₂O₅ on spent FCC catalyst. The (111) plane of spent FCC catalyst loaded with V₂O₅ and TiO₂ sample is 1.404 nm, which is higher than that of the zeolite Y (1.395 nm). The amount of adsorption of MB and the photocatalytic activity for the degradation increased with increasing the interplanar spacing of the (111) plane of sample. We fabricated of spent FCC catalyst composites by loaded V₂O₅ and TiO₂, which effectively solved the spent FCC catalyst disposal problem. The efficiency of the developed sample provides a potentially economical way of degrading MB.

Diamines as interparticle linkers for silica–titania supported PdCu bimetallic nanoparticles in Chan–Lam and Suzuki cross-coupling reactions

The remarkable synergetic effect between Pd and Cu, and basic nitrogen sites on the support effectively stabilize the nanoparticles and enhance the catalytic activity.

Investigation of the influence of vanadium, iron and nickel dopants on the morphology, and crystal structure and photocatalytic properties of titanium dioxide based nanopowders

Photoactive V, Fe and Ni doped TiO2 (M-TiO2) nanopowders were synthesized by a modified two-step sol-gel process in the absence of additives. Titanium oxychloride, which is a rarely-used TiO2 precursor was used to yield M-TiO2 photocatalysts with preferential photochemical performance in the presence of natural solar irradiation. The obtained samples were calcined at different calcination temperatures ranging from 450 to 800°C to evaluate the influence of the sintering on the physicochemical properties. The properties of the obtained samples were examined by XRF, XRD, Raman spectroscopy, UV-visible DRS, XPS, nitrogen gas physisorption studies, SEM-EDAX and HRTEM analyses. Structural characterization of the samples revealed the incorporation of these transition metal element into TiO2. It was also depicted that the morphology, crystal structure, optical and photochemical properties of the obtained samples were largely dependent on the calcination temperature and the type of dopant used during the preparation process. The photochemical performance of the samples was investigated in the photodegradation of methylene blue in the presence of natural sunlight. The experimental results indicated that the VT600 sample possessed the highest activity due to its superior properties. This study provides a systematic preparation and selection of the precursor, dopant and calcination temperature that are suitable for the formation of TiO2-based heterogeneous photocatalysts with appealing morphology, crystal structure, optical and photochemical properties for myriad of applications.

Photocatalytic decomposition of cortisone acetate in aqueous solution

The photocatalytic decomposition of cortisone 21-acetate (CA), a model compound for the commonly used steroid, cortisone, was studied. CA was photocatalytically decomposed in a slurry reactor with the initial rates between 0.11 and 0.46 mg L(-1)min(-1) at 10 mg L(-1) concentration, using the following heterogeneous photocatalysts in decreasing order of their catalytic activity: ZnO>Evonik TiO2 P25>Hombikat TiO2>WO3. Due to the lack of ZnO stability in aqueous solutions, TiO2 P25 was chosen for further experiments. The decomposition reaction was found to be pseudo-first order and the rate constant decreased as a function of increasing initial CA concentration. Changing the initial pH of the CA solution did not affect the reaction rate significantly. The decomposition reaction in the presence of the oxidizing sacrificial agent sodium persulfate showed an observed decomposition rate constant of 0.004 min(-1), lower than that obtained for TiO2 P25 (0.040 min(-1)). The highest photocatalytic degradation rate constant was obtained combining both TiO2 P25 and S2O8(2-) (0.071 min(-1)) showing a synergistic effect. No reactive intermediates were detected using LC-MS showing fast photocatalytic decomposition kinetics of CA.

A sol–gel route to synthesize SiO2/TiO2 well-ordered nanocrystalline mesoporous photocatalysts through ionic liquid control

SiO₂/TiO₂ composite photocatalysts were prepared through a sol–gel method, using an ionic liquid (IL), 1-butyl-3-methylimidazole bromide ([Bmim]Br), as a structure controlling agent.