Search results for "Vanadyl acetylacetonate"
showing 5 items of 5 documents
Templated growth of smart coatings: Hybrid chemical vapour deposition of vanadyl acetylacetonate with tetraoctyl ammonium bromide
2009
Hybrid aerosol assisted and atmospheric pressure chemical vapour deposition methodology has been utilised to produce thin films of vanadium dioxide from vanadyl acetylacetonate. Tetraoctyl ammonium bromide (TOAB) was used in the aerosol precursor solution. The films were analysed by X-ray diffraction, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy. Their optical and thermochromic behaviour was also determined. It was found that the use of TOAB had a templating effect that led to a halving in the particle size and that this consequently led to a significant decrease in the thermochromic transition temperature of the films to 34 8C.
Templated growth of smart nanocomposite thin films: Hybrid aerosol assisted and atmospheric pressure chemical vapour deposition of vanadyl acetylacet…
2009
Hybrid aerosol assisted and atmospheric pressure chemical vapour deposition methodology has been utilised to produce nanocomposite thin films of gold nanoparticles and vanadium dioxide from vanadyl acetylacetonate and auric acid. The addition of tetraoctyl ammonium bromide (TOAB) to the precursor Solution gave control of the size and distribution of gold nanoparticles in the vanadium oxide matrix. These reactions led to vanadium dioxide films with reduced crystallite sizes and enhanced thermochromic properties. The films were analysed by X-ray diffraction, scanning electron microscopy and X-ray photoelectron spectroscopy. Their optical and thermochromic behaviour was also determined, This h…
Preparation, characterization and catalytic properties of vanadium oxides supported on calcined Mg/Al-hydrotalcite
1995
Abstract Vanadium oxide supported on calcined hydrotalcite has been investigated for the oxidehydrogenation of n-butane in the 500–550°C temperature interval. Hydrotalcite (Mg/Al atomic ratio of 2.77), consisting of a single phase only, has been employed as a support precursor. The vanadium catalysts (0–50, referred as wt.-% V 2 O 5 ) were prepared by impregnation of calcined hydrotalcite (450°C) with ammonium metavanadate (in an aqueous solution) or vanadyl acetylacetonate (in a methanolic solution), and then calcined at 600°C for 4 h. During the impregnation step, the support is transformed into hydrotalcite if aqueous solutions are used. However, it is not modified if methanolic solution…
Oxidative dehydrogenation of n-butane on MgO-supported vanadium oxide catalysts
1998
Abstract Vanadium–magnesium oxide (VMgO) catalysts have been prepared, characterized and tested in the ODH of n-butane. The catalysts were prepared by two variations of the wet-impregnation method using aqueous ammonium metavanadate or organically-based methanolic vanadyl acetylacetonate solutions. The catalyst surface area depends on the vanadium content and the preparation method. Catalyst characterization (i.e. XRD, 51V NMR, FTIR, LRS) results indicate the presence of poor crystalline Mg-orthovanadate (Mg3V2O8), while the presence of other Mg-vanadates is not clear. Oxygen isotopic-exchange experiments on VMgO catalysts indicate an R2 process: [ 18 O 2 +2 16 O 2− (s) → ( 18 O 18 O 16 O 1…
Low-temperature metastabilization of tetragonal V+4-containing ZrO2 solid solutions
2001
Abstract The formation and characterization of tetragonal vanadium–zirconia solid solutions with different vanadium contents have been investigated. Vanadium–zirconia precursors were prepared by gelling mixtures of zirconium n-propoxide and vanadyl acetylacetonate, and studied over the range of temperature up to the tetragonal–monoclinic phase transformation. The formation of the tetragonal phase has been investigated by X-ray powder diffraction (XRD). It was found that it took place after annealing around 450°C for all specimens independently of the vanadium loading. In contrast, the temperature for the subsequent tetragonal to monoclinic transformation was dependent on the nominal vanadiu…