Topic
Vanadate
About: Vanadate is a research topic. Over the lifetime, 4497 publications have been published within this topic receiving 120109 citations. The topic is also known as: vanadate.
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TL;DR: Kakuta et al. as discussed by the authors showed that the vanadate molecule adopts a trigonal bipyramidal geometry with its equatorial oxygens coordinated to these three residues.
128 citations
TL;DR: In this paper, Raman and infrared spectroscopies were used to examine the surface structure of vanadia and the hydroxyl groups of titania along with the sulfate species on the catalyst surface.
Abstract: V2O5 supported on sulfated TiO2 catalyst was investigated by using Raman and infrared spectroscopies to examine the surface structure of vanadia and the hydroxyl groups of titania along with the sulfate species on the catalyst surface. The surface structure of vanadia plays a critical role, particularly for the reduction of NO by NH3. The polymeric vanadate species on the catalyst surface is the active reaction site for this reaction system. The surface sulfate species enhanced the formation of the polymeric vanadate by reducing the available surface area of the catalyst. The formation of the polymeric vanadate species on the catalyst surface also depends on the number of hydroxyl groups on the support. Both the sulfate and the vanadate species strongly interacted with the hydroxyl groups on titania. The fewer the number of the hydroxyl sites on the catalyst surface became by increasing the calcination temperatures, the more the polymeric vanadate species formed. A model was proposed to elucidate the progressive alteration of the surface structure of vanadia by the amounts of V2O5 loadings and the sulfate species on the catalyst surface.
128 citations
TL;DR: It is proposed that an opportunity exists for vanadate to become a more commonly utilized component of the macromolecular crystallographer's toolbox for visualization of transition state analogs.
128 citations
TL;DR: Chitosan is very efficient at removing vanadium from dilute solutions: sorption capacity can reach 400−450 mg V g-1 under optimum experimental conditions, which correspond to pH 3 as discussed by the authors.
Abstract: Chitosan is very efficient at removing vanadium from dilute solutions: sorption capacity can reach 400−450 mg V g-1 under optimum experimental conditions, which correspond to pH 3. In acidic solutions, the chitosan's amine groups are protonated, and vanadate anions can be exchanged with counterions bound to −NH3+ sites. A correlation is observed between the speciation diagram and the sorption isotherms, and it appears that decavanadate species are more favorable to sorption than other anionic vanadate species. Selecting experimental conditions under which decavanadate ions are the predominant form of vanadium results in enhanced sorption capacities and improved sorption kinetics. The results obtained in the study of vanadate desorption confirm the high affinity of chitosan for these polyoxoanions.
128 citations
TL;DR: In this paper, the electronic structure of four ternary-metal oxides containing isolated vanadate ions is studied by high-pressure optical-absorption measurements up to 20 GPa.
Abstract: The electronic structure of four ternary-metal oxides containing isolated vanadate ions is studied. Zircon-type YVO4, YbVO4, LuVO4, and NdVO4 are investigated by high-pressure optical-absorption measurements up to 20 GPa. First-principles calculations based on density-functional theory were also performed to analyze the electronic band structure as a function of pressure. The electronic structure near the Fermi level originates largely from molecular orbitals of the vanadate ion, but cation substitution influence these electronic states. The studied ortovanadates, with the exception of NdVO4, undergo a zircon-scheelite structural phase transition that causes a collapse of the band-gap energy. The pressure coefficient dEg/dP show positive values for the zircon phase and negative values for the scheelite phase. NdVO4 undergoes a zircon-monazite-scheelite structural sequence with two associated band-gap collapses.
127 citations