Photocatalyzed preferential oxidation of CO under simulated sunlight using Au-transition metal oxide-sepiolite catalysts.

In the present study a series of Au-transition metal oxides supported on a clay mineral such as sepiolite were tested in the preferential oxidation of CO in an excess of H under simulated solar light irradiation and in the absence of light, at 30 °C and atmospheric pressure. Transition metal oxides (ZnO, FeO, NiO, MnO, and CoO) were dispersed over the sepiolite surface where, subsequently, Au nanoparticles with an average particle size between 2 and 3 nm were successfully deposited-precipitated. The obtained photocatalysts were characterized by XRD, XRF, DRUV-Vis, N adsorption-desorption and HRTEM in order to evaluate the optical, structural and chemical properties of the prepared samples.

CO Preferential Photo-Oxidation in Excess of Hydrogen in Dark and Simulated Solar Light Irradiation over AuCu-Based Catalysts on SBA-15 Mesoporous Silica-Titania.

In this work, SBA-15 silica and silica-titania have been used as supports for photocatalysts based on AuCu alloy (Au:Cu = 1) to be used in the preferential oxidation of CO (CO-PROX) in excess of hydrogen at room temperature and atmospheric pressure both in the dark and under simulated solar light irradiation. To study their textural, structural, chemical and optical properties, the samples were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), adsorption-desorption of N₂ at -196 °C, C and Si solid state nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS) and diffuse reflectance ultraviolet-visible (DRUV-vis) spectroscopy. Titanium was present mainly in the form of titania aggregates, but also as small particles interacting with the SBA support.

Au and AuCu Nanoparticles Supported on SBA-15 Ordered Mesoporous Titania-Silica as Catalysts for Methylene Blue Photodegradation.

The photocatalytic degradation of methylene blue (MB) dye has been performed under UV irradiation in aqueous suspension, employing photocatalysts based on Au (1.5 wt %) and AuCu (Au/Cu = 1, 2.0 wt %), and supported on SBA-15-ordered mesoporous silica, with and without titania (Si/Ti = 3), in order to evaluate the versatility of this mesoporous support in this type of reaction of great impact from the environmental point of view.

Stepwise dansyl grafting on the kaolinite interlayer surface.

Here we describe the step-wise grafting of the fluorophore dansyl chloride on the interlayer aluminol groups of kaolinite. The modified clay was characterized by powder RD, TGA, FT-IR and (27)Al, (19)Si, (13)C MAS-NMR, which confirmed the achievement of the clay functionalization. The photophysical properties of the resulting nanohybrid material were evaluated by photoluminescence excitation and emission measurements.

Gold stabilized aqueous sols immobilized on mesoporous CeO2-Al2O3 as catalysts for the preferential oxidation of carbon monoxide.

Nanostructured Au/Al(2)O(3)-CeO(2) catalysts with a low content of precious metal (0.9% wt.) were prepared immobilizing two different stabilized Au sols on a high surface area Al(2)O(3)-CeO(2) mixed oxide with a uniform pore size distribution, synthesized by a one-pot methodology.

Photoexcited triplets of dyes in zeolitic nanostructured channels. A time resolved EPR study.

Two dyes (4-nitrostilbene, NST and 4-N,N-dimethylamino-4'-nitrostilbene, DANS) included in zeolites with nanometric channels and different Si : Al ratios have been photoexcited and their triplet state studied by time resolved EPR (TR-EPR). This is the first time that a TR-EPR spectrum of photoexcited triplet states of dyes in zeolites has been observed. The zeolites used were ZSM-5 and mordenite, with either protons or lithium as charge compensating ions, and the aluminium-free porosil.