Authors:Maria Kurzawa, Anna Blłońska-Tabero, and Izabella Rychłowska-Himmel
Phase equilibria in subsolidus area in the ZnO-V2O5-Fe2O3 system have been investigated over the whole concentration range of the oxides. The components of this system form two compounds:
Zn2FeV3O11 and Zn3Fe4(VO4)6. A solidus area projection onto the component concentration triangle plane of the ZnO-V2O5-Fe2O3 system has been constructed using DTA and XRD methods. 11 subsidiary subsystems can be distinguished in this system. Melting
temperatures of mixtures of solid phases coexisting at equilibrium in each of subsidiary subsystems were determined.
the catalytic properties of such compounds are related to the presence of isolated VO 4 tetrahedrons in them [ 6 , 7 ]. This finding has prompted us to undertake a comprehensive study of CoO–In 2 O 3 –V2O5 system.
Two versions of the CoO–V
In this work it has been established which compounds finally are formed in air in the two-component CuO-V2O5 and CuO-α-Sb2O4 systems. Unknown thermal properties of CuV2O6, Cu2V2O7 and Cu11V6O26 have been established. Reactivity of the oxides and phase relations in the ternary V2O5-CuO-α-Sb2O4 system in air have been studied by using XRD and DTA methods. The results have showed the reaction of V2O5, CuO with α-Sb2O4 does not produce any compound where all the three oxides would be involved. It has been established that the α-Sb2O4 reacts and forms binary phases independently with CuO or V2O5. On the base of these results the investigated system was divided into subsidiary subsystem in which CuSb2O6 remains at equilibrium in the solid state with other phases formed in corresponding binary systems.
Authors:M. Niyaz Ahamad, Rahul Vaish, and K. B. R. Varma
glass transition and crystallization kinetics of 2TeO 2 –V2O5 glasses.
2TeO 2 –V2O5 (TVO) glasses were fabricated via the conventional melt-quenching technique. For this, stoichiometric ratio of TeO 2 (99
doped V2O5 /SiO 2 catalysts for the ODP reaction. The effects of different impregnation sequences of F–V2O5 /SiO 2 catalysts were investigated. The characterizations of X-ray photoelectron spectroscopy (XPS), N 2 adsorption–desorption, Scanning
] investigated the amination of toluene to toluidines with hydroxylamine sulfate in the presence of Na 4 PW 11 O 39 Fe(H 2 O), V2O5 /SiO 2 and V2O5 /TiO 2 catalysts, the yield of toluidines was only around 26% at optimal conditions. Yu et al. [ 22
It is known that the components of the ternary systems MO–V2O5 –Fe 2 O 3 as well as the compounds existing in their lateral systems catalyze a lot of chemical reactions [ 1 – 3 ]. Therefore, it can be expected
Authors:S. Khalameida, J. Skubiszewska-Zięba, V. Zazhigalov, R. Leboda, and K. Wieczorek-Ciurowa
Mechanochemical treatment (MChT) in various media (water, air, ethanol) of the V2O5/ammonium dimolybdate composition at the ratio V:Mo = 0.7:0.3 has been carried out. Physicochemical transformations in this
system have been studied by means of X-ray powder diffraction (XRD) and thermal analysis as well as FTIR spectroscopy. Ammonium
dimolybdate undergoes hydration with formation of 4-aqueous ammonium paramolybdate during the MChT in water. Changes of phase
and chemical composition at activation are determined first of all by nature of medium in which milling was carried out. Maximal
interaction of components occurs during modification of the studied system in water.
Temperature-programmed reductions (TPR) with H2 of both pure V2O5 and coprecipitated V2O5−TiO2 systems with different titanium concentrations was performed. The original and the reduced samples following each TPR step
were characterized by X-ray diffraction, Fourier transform infrared analysis and scanning electron microscopy.
Within the temperature range in which TPR analysis was carried out (100–600°C) the V2O5 phase was reduced in two or three steps, while no variation in the TiO2 phase (anatase or rutile) was observed.
In the first reduction step only superficial reduction of the oxides was detected. In the following steps, the H2 reacted with oxygen atoms of the V=O and V−O−V bonds. This led to important changes in the structure and morphology of the
The experimental evidence allowed the conclusion that titanium stabilizes certain phases of vanadium oxides in which vanadium
appears as V(+4) or as a mixture of V(+4) and V(+5). Moreover, when moderate and high titanium concentrations were used, the
reduction temperature of the bulk V2O5 decreased markedly.