A kinetic study of the preferential oxidation of CO in H2 rich streams (CO-PrOx) over a cerium-copper oxide (CeCu) and a gold catalyst supported on cerium-iron oxide (Au/CeFe) is presented. The gold catalyst is very active but the CeCu oxide is more selective. A kinetic model describing the CO-PrOx system with CO2 and H2O in…
Different metallic supports (aluminum foams of 40ppi, honeycomb monolith and micromonolith of 350 and 1180cpsi, respectively) have been loaded with a 20%Co-0.5%Re/γ-Al2O3 catalyst by the washcoating method. Layers of different thicknesses have been deposited onto the metallic supports. The catalytic coatings were characterized measuring their textural properties, adhesion and morphology. These structured catalysts have been…
Nanocrystalline anatase (TiO2) thin films prepared by a physical vapour deposition method were nitrided by annealing in flowing NH3 at temperatures ranging between 650 °C and 700 °C. It was established that there was a narrow window of temperatures which allowed both incorporation of interstitial nitrogen into the films with retention of the anatase phase…
The objective of the present work is the comparative study of the behaviour of the Nb- and Ti-based additives in the MgH2 single hydride and the MgH2 + 2LiBH4 reactive hydride composite. The selected additives have been previously demonstrated to significantly improve the sorption reaction kinetics in the corresponding materials. X-Ray Diffraction (XRD), X-Ray Absorption…
A series of titanium oxide catalysts modified with yttrium has been prepared by sol-gel method and their structural properties have been studied. The incorporation of yttrium in the titania lattice favors the formation of oxygen vacancies while at low Y loadings the anatase structure is preserved. The catalytic activity of these solids for CO oxidation…
Crystalline monolayers of three aldehydes with an odd number of carbon atoms in the alkyl chain (C7, C9 and C11) at low coverages are observed by a combination of X-ray and neutron diffraction. Analysis of the diffraction data is discussed and possible monolayer crystal structures are proposed; although unique structures could not be ascertained for…
The outer surfaces of epidermal cell walls are impregnated with an extracellular matrix called the cuticle. This composite matrix provides several functions at the interface level that enable plants to thrive in different habitats and withstand adverse environmental conditions. The lipid polymer cutin, which is the main constituent of the plant cuticle, has some unique…
Monodisperse YF3:Tm3+/Yb3+ nanocrystals have been synthesized to explore the visible up-converting properties under near infrared (975 nm) excitation. It has been found that the nanoparticles exhibit intense red up-converted emissions, in addition to the characteristic UV and blue Tm3+-bands. It is demonstrated that, by carefully selecting Tm3+ and Yb3+ contents, the relative intensity of the…
Phase transition of anatase nanoparticles into the phases TiO2-II and rutile under grinding was studied. The addition of ammonium carbamate to the reaction mixture inhibits the phase conversion and the cold welding of particles. The UV-visible absorption spectrum showed narrowing the band gap width after grinding with an ammonium carbamate additive resulting in shift of…
The plastic flow of TiCxN1-x-CoTi cermets has been investigated by uniaxial compression tests carried out in argon atmosphere at temperatures between 1100 and 1200°C. Two different cermets, with 5wt.% W or WC content as sintering additives, have been explored to assess the influence of the sintering additives on creep. The microstructural observations of deformed samples…