Vanadium oxides, physicochemical

Table 2. Some physicochemical properties of vanadium oxides.

The above techniques have a wide array of applications, including those that are both analytical and physicochemical (such as bonding) in nature. Typical examples of research include the surface chemistry of ferrite minerals (38) and the valence states of copper in a wide array of copper (39) minerals. Other areas of bonding that have been studied include the oxidation state of vanadium (40) in vanadium-bearing aegirities (also using x-ray photoelectron spectroscopy) and the. surface features of titanium perovskites (41). ... 

It is now considered, by most groups working in this area, that vanadyl pyrophosphate (VO)2P207 is the central phase of the Vanadium Phosphate system for butane oxidation to maleic anhydride (7 ). However the local structure of the catalytic sites is still a subject of discussion since, up to now, it has not been possible to study the characteristics of the catalyst under reaction conditions. Correlations have been attempted between catalytic performances obtained at variable temperature (380-430 C) in steady state conditions and physicochemical characterization obtained at room temperature after the catalytic test, sometimes after some deactivation of the catalyst. As a consequence, this has led to some confusion as to the nature of the active phase and of the effective sites. (VO)2P207, V (IV) is mainly detected by X-Ray Diffraction. 

Baldovino-Medrano VG, Farin B, Gaigneaux EM. Establishing the role of graphite as a shaping agent of vanadium-aluminum mixed (hydr)oxides and their physicochemical properties and catalytic functionalities. ACS Catalysis. 2012 2(3) 322-336. 

Another case where the test reaction has been used to correlate catalytic behavior and physicochemical properties, is the interesting vanadium-containing system studied by Trikalitis and Pomonis (1995). They studied the transformation of isopropanol over Lai -xS VOb. This solid contains vanadium in at least two oxidation states, Vm and VIv. The systematic variation of the Sr content modifies the acid-base balance on the surface... 

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