Search results for "Support"
showing 10 items of 2310 documents
Honeycomb supported Co3O4/CeO2 catalysts for CO/CH4 emissions abatement: effect of low Pd-Pt content on the catalytic activity
2007
Abstract A structured Co3O4–CeO2 composite oxide, containing 30% by weight of Co3O4, has been prepared over a cordieritic honeycomb support. The bimetallic, Pd–Pt catalyst has been obtained by impregnation of the supported Co3O4–CeO2 with Pd and Pt precursors in order to obtain a total metal loading of 50 g/ft3. CO, CH4 combined oxidation tests were performed over the catalyzed monoliths in realistic conditions, namely GHSV = 100,000 h−1 and reaction feed close to emission from bi-fuel vehicles. The Pd–Pt un-promoted Co3O4–CeO2 is promising for cold-start application, showing massive CO conversion below 100 °C, in lean condition. A strong enhancement of the CH4 oxidation activity, between 4…
Effect of framework type on survival probability of implant-supported temporary crowns : an in vitro study
2020
Made available in DSpace on 2020-12-12T01:29:18Z (GMT). No. of bitstreams: 0 Previous issue date: 2020-01-01 Background: This in vitro study evaluated the effect of framework type on the survival probability of temporary implant-supported crowns and on the implant platform structure after dynamic fatigue. Material and Methods: Thirty (30) external hexagon implants (3.75 x 10 mm) were embedded in acrylic resin following the ISO-14801. Standardized temporary crowns (n=10, N=30) were manufactured in acrylic resin and divided according to the framework type: Total plastic, Plastic with CoCr base and Titanium. The crowns were installed onto the implants (20N. cm) and fatigued (100N, 2 Hz) to det…
Total oxidation of VOCs on mesoporous iron oxide catalysts: Soft chemistry route versus hard template method
2016
9 figures, 3 tables.-- Supplemantary information available
Evidence of hexagonal WO3 structure stabilization on mica substrate
2009
International audience; WO3 nanorods are grown by a simple vapor deposition method on a mica substrate and characterized by Selected Area Electron Diffraction and Energy Dispersive X-rays Spectroscopy. Experimental results show the clear evidence of an unexpected WO3 hexagonal structure as well as an epitaxial growth on the mica substrate. Besides, potassium is evidenced inside the nanorods. It is thus deduced that a metastable WO3 hexagonal phase is stabilized by epitaxy through a tungsten bronze interlayer having same hexagonal structure.
A photoemission study of molybdenum hexacarbonyl adsorption and decomposition on TiO2(110) surface.
2007
International audience; The adsorption and decomposition of molybdenum hexacarbonyl on (110) TiO2 surfaces were studied using both core levels and valence band photoemission spectroscopies. It was found that after an adsorption at 140 K, when going back to room temperature, only a small part of molybdenum compounds, previously present at low temperature, remained on the TiO2 surface. This indicates that the desorption temperature on such a surface is lower than the decomposition one. The use of photon irradiation to decompose the hexacarbonyl molecule was also studied. It was shown that during such a decomposition molecular fragments were chemisorbed on the surface allowing a higher amount …
On-surface synthesis on a bulk insulator surface
2018
On-surface synthesis has rapidly emerged as a most promising approach to prepare functional molecular structures directly on a support surface. Compared to solution synthesis, performing chemical reactions on a surface offers several exciting new options: due to the absence of a solvent, reactions can be envisioned that are otherwise not feasible due to the insolubility of the reaction product. Perhaps even more important, the confinement to a two-dimensional surface might enable reaction pathways that are not accessible otherwise. Consequently, on-surface synthesis has attracted great attention in the last decade, with an impressive number of classical reactions transferred to a surface as…
Manufacturing and testing of a metal supported Ni-YSZ/YSZ/La2NiO4 IT-SOFC synthesized by physical surface deposition processes
2017
International audience; The manufacture of the last generation metal supported IT-SOFC complete cell by dry surface deposition pro-cesses is really challenging. Atmospheric Plasma Spraying (APS) and Reactive Magnetron Sputtering (RMS) processes are respectively adapted to deposit Ni-YSZ anode and YSZ electrolyte layers. RMS is also used to coat a thin and dense La2NiO4 (LNO) cathode layer. In this work, we have realized a complete cell on metallic support (ITM) produced by PLANSEE SE. The innovative LNO cathode layer was compared with screen-printed LNO layers, with and without RMS bonding layer. Electrochemical and Voltammetry tests were performed on these samples. It reveals lower perform…
Nanoparticles of AlTiZr mixed oxides as support of hydrodesulfurizaton catalysts: Synthesis and characterisation
2012
Abstract TiAlZr mixed oxides, synthesized using sol–gel method, were characterized and used as supports of hydrodesulfurization catalysts (12 wt% Mo) prepared by impregnation either with molybdenum heteropolyacid H3PMo12O40 or its cobalt salt Co1.5PMo12O40. Structure, morphology and textural properties of oxides and catalysts were characterized using X-ray powder diffraction (XRD), Raman spectroscopy, Nitrogen adsorption porosimetry, TEM-EDS, temperature-programmed desorption (TPD) and temperature-programmed reduction (TPR) techniques. Activity of the catalytic systems was tested in thiophene hydrodesulfurization (HDS). No formation of a new oxide phase was revealed in the synthesized mixed…
Ni-Based Catalysts for Low Temperature Methane Steam Reforming: Recent Results on Ni-Au and Comparison with Other Bi-Metallic Systems
2013
Steam reforming of light hydrocarbons provides a promising method for hydrogen production. Ni-based catalysts are so far the best and the most commonly used catalysts for steam reforming because of their acceptably high activity and significantly lower cost in comparison with alternative precious metal-based catalysts. However, nickel catalysts are susceptible to deactivation from the deposition of carbon, even when operating at steam-to-carbon ratios predicted to be thermodynamically outside of the carbon-forming regime. Reactivity and deactivation by carbon formation can be tuned by modifying Ni surfaces with a second metal, such as Au through alloy formation. In the present review, we su…
Preparation of Catalysts and Photocatalysts Used for Similar Processes
2019
Abstract This chapter reports the main techniques used to synthesize powders and films of heterogeneous catalysts and photocatalysts, often used for similar processes. Traditional preparation processes of bulky (photo)catalysts including precipitation, sol–gel technique, hydrothermal or solvothermal method, solid-state reactions, and flame syntheses were briefly described. The sonochemical method and microwave irradiation technique were also considered. The syntheses of supported catalysts by different techniques, including deposition–precipitation, impregnation, and wet coating technologies were also described. Moreover, a survey is reported of methods to deposit thin films of catalysts on…