A series of supported V2O5/Al2O3 catalysts were synthesized by incipient wetness impregnation with vanadium isopropoxide in isopropanol solutions and subsequent calcination. The vanadium surface density was varied from 0.3 to 11.4 V atoms/nm2 spanning the sub-monolayer and above-monolayer regions. The resulting supported vanadium oxide catalysts were physically characterized with in situ Raman ...

The influence of various preparation methods on the performance of V-Nb-0 catalysts has been investigated. It was found that the activity and selectivity of a vanadium site depend on the nature of the neighbouring atoms. Vanadium neighbours provide activity, while niobium neighbours provide selectivity. Careful preparation of these catalysts ensures a homogeneous distribution and good mixing of...

During asymmetric cyanohydrin synthesis catalysed by vanadium(V)oxo(salen) complexes, the catalysts are reduced to vanadium(IV)oxo(salen) as determined by EPR spectroscopy; the reducing agent is cyanide which is oxidised to cyanogen via a non-radical mechanism.

The possibility of application of 4-nitrocatechol (4-NC) - tetrazolium salt - organic solventsystems for liquid-liquid extraction-spectrophotometric vanadium (IV and V) speciation wasstudied. Six commercially available tetrazolium salts (2,3,5-triphenyltetrazolium chloride (TTC),3-(2-naphtyl)-2,5-diphenyltetrazolium chloride (Tetrazolium Violet, TV); 3-(4,5-dimethyl-2-thiazol)-2,5-diphenyltetra...

Bis(peroxo)vanadium(V) complexes are widely investigated as anticancer agents. They exert their antitumor and cyctotoxic effects through inhibition of tyrosine phosphatases and DNA cleavage, respectively. The latter process remains poorly understood. The mechanism of DNA cleavage by NH(4)[(phen)V(O)(eta(2)-O(2))(2)] (phen = 1,10-phenanthroline) was investigated. Kinetic studies on DNA cleavage ...

The phase composition of vanadium and vanadium-antimony-containing samples γ-Al2O3 the degree oxidation in them were examined by XRD EPR methods, respectively. data spectroscopy show formation highly dispersed vanadium-oxygen vanadiumantimony-oxygen structures on surface support. It is shown that spectra studied are due to "isolated" ions with an state +4 nonstoichiometric vanadium-antimony-oxy...

Vanadium-niobium oxide catalysts containing variable amounts of vanadium and prepared by coprecipitation were investigated using 51V solid-state NMR. It was found that, in samples containing less than about 8 mol % V2O5, vanadium occurs in three different oxygen environments: in isolated tetrahedra, in comer-sharing tetrahedra (pyrovanadate), and in distorted octahedra. The number of octahedral...