Aldo Talon

Liquid phase acetophenone hydrogenation on Ru/Cr/B catalysts supported on silica

The liquid phase hydrogenation of acetophenone was studied over a series of silica supported bimetallic catalysts with various Ru/Cr atomic ratios. The catalysts were prepared by reduction of the metal salts with NaBH4 aqueous solutions and were characterised by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) (ESCA). The hydrogenation reaction was carried out in batch at a hydrogen pressure of 9 bar. The selectivity towards reduction of the carbonyl function increases with the increasing amount of Cr ions added.

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. The samples were characterized by elemental analysis, N(2) physisorption, XRPD, TEM and (27)Al-MAS NMR techniques. The catalytic activity of the two samples in the preferential oxidation of CO in excess of H(2) (CO-PROX) was comparatively evaluated in the 35-110 degrees C temperature range. The Au-THPS/AlCe20 sample, prepared immobilizing a sol obtained reducing an aqueous solution of gold tetrachloroaurate salt with bis[tetrakis(hydroxymethyl)phosphonium sulfate], resulted very active and selective at low temperatures and its catalytic activity was correlated with the structural characteristics of the metal particles and of the ordered mesoporous 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. Samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N2 adsorption-desorption at −196 °C, and X-ray photoelectron spectroscopy (XPS), so as to study their structural, optical, and chemical properties. All the prepared catalysts were found to be active in the test reaction. The bimetallic AuCu-based catalysts attained very high MB degradation values, in particular AuCu/SBA-15 titania-silica sample reached 100% of dye oxidation after the monitored reaction period (120 min).

Gold-Ceria SBA-15 supported catalyst for CO preferential oxidation: Surface and reactivity studies

In this article, the preparation and application of gold and cerium catalysts supported on zirconium-doped mesoporous silica SBA-15 was studied. These materials have been prepared by two different methods and characterized to investigate their textural properties, dispersion of the active phases and oxidation states. Both materials exhibit a marked catalytic activity. The size of the gold nanoparticles is directly related to the CO conversion rate and to the selectivity towards CO2 exhibiting a strong temperature dependence. An X-ray photoelectron spectroscopic study of the composition and chemical state of the nanoparticles indicates the presence of Au in a metallic state. Transmission electron microscopic micrographs indicate that the best catalyst shows a higher dispersion of Au in spite of its lower gold surface content.

Synthesis, characterization and catalytic activity of aluminum pillared synthetic Ti-, Fe- or Zn-substituted smectites

ABSTRACT Synthetic smectites framework substituted with Ti, Fe, and Zn were synthetized in hydrothermal conditions. The materials were characterized by XRD, nitrogen adsorption, MAS-NMR. FT-IR spectroscopy of adsorbed pyridine and analysis of product distribution in the 1-butene isomerization was used to evaluate the surface acidity. Chemical properties were correlated to the nature and presumed lattice location of the framework substituents.

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, 13C and 29Si 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. In both catalysts, the metal alloy nanoparticles displayed an average size of 4 nm as demonstrated by TEM measurements. AuCu/Ti-SBA turned out to be photoactive and selective in the photo-CO-PROX reaction showing the highest activity, with conversion and selectivity towards CO2 of 80%, due both to the presence of titania incorporated in SBA-15 and to the synergistic effect of Cu when alloyed with Au.

A novel triphenylamine-based dye sensitizer supported on titania nanoparticles and the effect of titania fabrication on its optical properties

A new synthesised triphenylamine-based dye having a branched structure with one OH-ending branch able to interact with the surface hydroxyl moieties of mesoporous TiO2 is reported. Optical properties of the dye-titania hybrid material are presented and the higher efficiency of the dye on pure anatase TiO2 compared to the commercial Degussa P25, which contains a rutile phase component, is confirmed. The optical and chemical properties of the dye make it a promising candidate as a metal-free dye for DSSCs or as a host for a variety of transition or main group metal ions for different applications.