Vanadium oxide systems

Li2S204 being the SEI component at the Li anode and the solid discharge product at the carbon cathode. The Li—SOCI2 and Li—SO2 systems have excellent operational characteristics in a temperature range from —40 to 60 °C (SOCI2) or 80 °C (SO2). Typical applications are military, security, transponder, and car electronics. Primary lithium cells have also various medical uses. The lithium—silver—vanadium oxide system finds application in heart defibrillators. The lithium—iodine system with a lithium iodide solid electrolyte is the preferred pacemaker cell. 

Figure 1.3 Activation of propane on a single-site vanadium oxide system. The figure is redrawn from the results of ref. [63],...

Lukas, I., C. Strusievici, and C. Liteanu. 1967. Vanadate compounds. VIII. Formation of bronzes in the silver vanadate-vanadium oxide system. Z. Anorg. Alg. Chem. 349 92-100. 

Toste s vanadium oxidation system currently has more limited scope, although it seems to be orthogonal to the Pd(II) system. Whereas the Pd-sparteine system was unable to effectively resolve a-hydroxycarbonyl compounds, these alcohols were resolved with high selectivity using vanadium(V) (Table 2) [11]. Benzylic and allylic a-hydroxycarbonyls performed well in the reactions (entries 1-3,6). Alkyl hydroxy esters were oxidized more slowly, but with high selectivity (entry 5). Activated alcohols not a to a carbonyl led to poor selectivity or low reactivity. 

Catalyst fusion is essential to bring and keep the py-rosulfatc-vanadium oxide system into a homogeneous state which is the basis for operating the system at the eutectic in the ternary phase diagram. The reaction mechanism and the fact that the operation point of the... 

Understanding the surface chemistry for supported vanadium oxide systems modified with phosphorus oxide at hydrocarbons oxidation... 

The lithium/silver vanadium oxide system has been developed for use in biomedical applications, such as cardiac defibrillators, neurostimulators and drug delivery devices. Electrochemical reduction of silver vanadium oxide (SVO) is a complex process and occurs in multiple steps from 3.2 to 2.0 V. This system is capable of high power, high energy density and high specific energy as is required for cardiac defibrillators, its principle application. 

Patterson and coworkers [5-18] have reported detailed liuninescence studies of selected transition metal complex ions in a varietjr of different environments such as in single crystals, in host crystals and on surfaces. For example, for vanadium oxide on a Si02 substrate the vanadium oxide (d ) is present in low concentrations on the substrate and detailed information can be obtained from the luminescence spectra about the vanadium oxide system [5]. This is a case where charge transfer transitions are present. This d° system is the first example to be discussed in Sect. 3. 

The general configuration of one system that has reached an advanced stage of development (22) is shown in Figure 1. The negative electrode consists of thin lithium foil. The composite cathode is composed of vanadium oxide [12037-42-2] 6 13 with polymer electrolyte. Demonstration... 

Other sohd cathode systems that have been widely investigated include those containing lithium cobalt oxide [12190-79-3] LiCo02 (51), vanadium pentoxide [1314-62-17, 20, and higher vanadium oxides, eg, 0 3 (52,53). 

Thus vanadium oxide (IV) eould be of interest for sensor systems. 

Investigations carried out within the past few years have revealed that multicomponent metal oxide systems may interact at interfaces by having one component form a two-dimensional metal oxide overlayer on the second metal oxide component. For example, vanadium oxide can be dispersed on Ti02, Zr02, Si02, AI2O3, and... 

Attenlion should be drawn to ihe use of tin oxide systems as heterogeneous catalysts. The oldest and mosi extensively patented systems are the mixed lin-vanadium oxide catalysis for the oxidation of aromatic compounds such as benzene, toluene, xylenes and naphthalene in the. synthesis of organic acids and acid anhydride.s. More recenily mixed lin-aniimony oxides have been applied lo the selective oxidaiion and ammoxidaiion of propylene to acrolein, acrylic acid and acrylonilrile. 

Other catalyst systems such as iron V2O5-P2O5 over silica alumina are used for the oxidation. In the Monsanto process (Figure 6-4), n-butane and air are fed to a multitube fixed-bed reactor, which is cooled with molten salt. The catalyst used is a proprietary modified vanadium oxide. The exit gas stream is cooled, and crude maleic anhydride is absorbed then recovered from the solvent in the stripper. Maleic anhydride is further purified using a proprietary solvent purification system. ... 

There are several ways to produce acrylic acid. Currently, the main process is the direct oxidation of acrolein over a combination molybdenum-vanadium oxide catalyst system. In many acrolein processes, acrylic acid is made the main product by adding a second reactor that oxidizes acrolein to the acid. The reactor temperature is approximately 250°C ... 

This reaction was first demonstrated over V, Mo and W oxides [6]. At 823 K vanadium oxide provided phenol selectivity up to 71%, which was much higher than it had been ever achieved with O2. This result stimulated further efforts in searching for more efficient catalytic systems. As a result, in 1988 three groups of researchers [7-9] have independently discovered ZSM-5 zeolites to be the most efficient catalysts. They allowed the reaction to proceed at much lower temperature (573-623 K) with nearly a 100% selectivity. Later, more complex aromatic compounds were also hydroxylated in this way [2]. 

Similar to molybdenum oxide catalyst the capability to emit singlet oxygen is inherent to Si02 doped by Cr ions as well. Similar to the case of vanadium oxide catalysts in this system the photogeneration occurs due to the triplet-triplet electron excitation transfer from a charge transfer complex to adsorbed oxygen. 

We refrain here from giving an extensive overview of studies on the surface structure of vanadium oxide nanolayers, as this has already been done for up to year 2003 in our recent review [97]. Instead, we would like to focus on prototypical examples, selected from the V-oxide-Rh(l 1 1) phase diagram, which demonstrate the power of STM measurements, when combined with state-of-the-art DFT calculations, to resolve complex oxide nanostructures. Other examples will highlight the usefulness of combining STM and STS data on a local scale, as well as data from STM measurements, and sample area-averaging spectroscopic techniques, such as XPS and NEXAFS, to derive as complete a picture as possible of the investigated system. 

The production of sulphuric acid by the contact process, introduced in about 1875, was the first process of industrial significance to utilize heterogeneous catalysts. In this process, SO2 was oxidized on a platinum catalyst to S03, which was subsequently absorbed in aqueous sulphuric acid. Later, the platinum catalyst was superseded by a catalyst containing vanadium oxide and alkali-metal sulphates on a silica carrier, which was cheaper and less prone to poisoning. Further development of the vanadium catalysts over the last decades has led to highly optimized modem sulphuric acid catalysts, which are all based on the vanadium-alkali sulphate system. 

Although much of the V NMR has been performed on model systems or catalytic materials containing vanadium, 29 >30 compounds such as V2O5 or VOPO4 are used in both the catalysis and lithium battery fields, and many of the results can be used to help elucidate the structures of vanadium-containing cathode materials. V NMR spectra are sensitive to changes in the vanadium coordination number and distortions of the vanadium local environments from regular tetrahedra or octahedra. >33 5>V isotropic chemical shifts of between —400 and —800 ppm are seen for vanadium oxides, and unfortunately, unlike... 

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