Hydrodechlorination of Aroclor 1260 in aqueous two-phase mixture catalyzed by biogenerated bimetallic catalysts

The PCBs are known recalcitrant and toxic pollutants and significant values of contamination could be found in water. PCBs can be hydrodechlorinated using Pd-based catalysts and hydrogen, but the research to identify more efficient heterogeneous catalysts, able to work in an aqueous phase, less sensible to deactivation and easily removable at the end of the treatment, remains a considerable interesting goal. A strain of Klebsiella oxytoca, DSM 29614, known to produce a specific exopolysaccaride (EPS), was grown in different media with sodium citrate or with sodium citrate plus ferric citrate, as sole energy and carbon sources under anaerobic conditions. The cultures were amended with 50 mg of palladium as Pd(NO3)2 to generate Pd-EPS (Pd content 13%) or FePd-EPS (Pd content 8.4%; Fe 7.4%) species which were secreted from the cells, isolated by treatment with a cold ethanol solution (70%) and dried under vacuum as powders. The catalytic ability of these mono- and bi-metallic species was tested in the hydrodechlorination reaction of the Aroclor 1260 PCBs mixture under aqueous biphasic conditions. Here we demonstrate that the degree of PCBs hydrodechlorination is dependent by the nature of catalyst and of base used to neutralize HCl produced, the bimetallic species being more active and an organic base resulting more effective. Working with a substrate/catalyst 8/1 molar ratio, at 3 MPa H2 and 60°C in 20 h a significant removal of highly chl orinated PCBs was obtained under the best conditions. The result seems promising for remediation of groundwater contaminated with PCBs

La0.8Sr0.2Ga0.8Fe0.2O3-\u3b4-based SOFCs electrode: effect of the synthetic procedures on properties and reactivity

A Sr and Fe doped lanthanum perovskite is prepared by Pechini procedure and characterized by means of different techniques. The reactivity in alcohol oxidation is also considered for applications in the anode compartment of IT-SOFCs

From La2O3 to LaCoO3: XPS analysis

Nanostructured LaCoO3 powder was prepared by a new approach: cobalt oxide nanoparticles were deposited, by wet impregnation, on the La2O3surface. The La2O3 support was prepared byprecipitation from a basic solution of La(NO3)3\ub76H2O. The precipitate was dried at 353 K for 2 h and calcined at 923 K for 6h in air. Nanostructured LaCoO3 was obtained by wet impregnation of La2O3 with aqueous solutions of Co(NO3)2\ub76H2O:Co/La nomimal 1.0 nominal atomic ratio is obtained from the precursors weighed quantities. The obtained suspension was maintained under stirring for two days and then kept in rest for one day. Water was evaporated in air and the obtained solid was dried at 353 K for2h and at 923K for 6h in air.The thermal treatment in air promotes a solid state reaction between La-O and Co-O and then the formation of LaCoO3

Large-Scale MOCVD Deposition of Nanostructured TiO2 on Stainless Steel Woven: A Systematic Investigation of Photoactivity as a Function of Film Thickness

Heterogeneous photocatalysis is considered as one of the most appealing options for the treatment of organic pollutants in water. However, its definitive translation into industrial practice is still very limited because of both the complexity of large-scale production of catalysts and the problems involved in handling the powder-based photocatalysts in the industrial plants. Here, we demonstrate that the MOCVD approach can be successfully used to prepare large-scale supported catalysts with a good photocatalytic activity towards dye degradation. The photocatalyst consisted of nanostructured TiO2 thin film deposited on a stainless steel mesh substrate. The film thickness, the morphological features, and the crystallographic properties of the different portions of the sample were correlated to the position in the reactor chamber and the reaction conditions. The photocatalytic activity was evaluated according to the international standard test ISO 10678:2010 based on methylene blue degradation. The photocatalytic activity is essentially constant (PMB over 40 µmol·m−2·h−1) throughout the film, except for the portion of sample placed at the very end of the reactor chamber, where the TiO2 film is too thin to react properly. It was assessed that a minimum film thickness of 250–300 nm is necessary to reach the maximum photocatalytic performance

La0.6Sr0.4Co1-yFeyO3- \u3b4 Powders Studied by X-ray Photoelectron Spectroscopy

Perovskite-type oxides are known to be very good oxidation catalysts. The redox properties of the TM cation, the availability of weakly bonded oxygen at the Surface and the presence of lattice defects have been often claimed as responsible for their catalytic activity. Moreover, their performances can be improved if they are nanodimensioned. The present stud focuses on the development of new LaCoO3-based catalysts for alcohol (methanol, ethanol) steam reforming. Several La0.6Sr0.4Co1-yFeyO3 (y=0.2, 0.5, 0.8) were prepared by the citrte gel method and calcined at 1073K for 5h in air. Herein the influence of the cobalt/iron ration on the surface properties was investigated

Au/CeO<SUB>2</SUB> Supported Nanocatalysts: Interaction with Methanol

The effect of preparation procedure (Direct Anionic Exchange, DAE, Deposition-Precipitation, DP, and wet Impregnation, IMP) and Au/Ce atomic ratio (0.018 and 0.066) on Au/CeO(2) supported nanocatalysts was investigated with respect to reactivity. XPS data suggest the presence of traces of Ce(III). Usually, gold is present as Au(0) but in the DAE sample with high Au content, traces of oxidized species are observed. The Au/Ce XPS atomic ratio is lower than the expected value. Au deposition decreases surface interaction with atmospheric moisture and carbon dioxide. Methanol interacts molecularly and dissociatively with the samples; methoxy groups are observed to be mono-coordinated at Ce(IV) at room temperature and bi-coordinated to Ce(IV) and Ce(III) at increasing temperature. Oxidation products (formates, carbonates, carbon dioxide) form at temperatures higher than 373-423 K; activity and selectivity in methanol oxidation reaction are influenced by the metal content and the preparation procedure