Vanadium compounds physical properties

Some properties of selected vanadium compounds are Hsted in Table 1. Detailed solubiUty data are available (3), as are physical constants of other vanadium compounds (4). Included are the lattice energy of several metavanadates and the magnetic susceptibiUty of vanadium bromides, chlorides, fluorides, oxides, and sulfides (5). 

Table 1. Physical Properties of Some Industrial and Other Selected Vanadium Compounds ...

Vanadium-Sodium Compounds Most Corrosive. Physical property data for vanadates, phase diagrams, laboratory experiments, and numerous field investigations have shown that the sodium vanadates are the lowest melting compounds and are the most corrosive to metals and refractories. These compounds are thought to form by either the vapor phase reaction of NaCI and V2O5 or by the combination of fine droplets of these materials upon the cooler parts of combustion equipment. 

Residua and heavy oils contain impurities other than sulfur, nitrogen, and oxygen, and the most troublesome of these impurities are the organometallic compounds of nickel and vanadium. The metal content of a residuum or heavy oil can vary from several parts per million (ppm) to more than 1000 parts per million (Table 6-15), and there does seem to be more than a chance relationship between the metals content of a feedstock and its physical properties (Reynolds, 1997 Speight, 1999). In the hydrodesulfurization of the heavier feedstocks the metals (nickel plus vanadium) are an important factor since large amounts (over 150 ppm) will cause rapid deterioration of the catalyst. The free metals, or the sulfides, deposit on the surface of the catalyst and within the pores of the catalyst, thereby... 

Several CT complexes of metal bis(arene) compounds containing, among others, the familiar organic acceptor TCNQ have been reported [71]. None of these materials has been shown to display physical properties superior to those of the metallocene systems. One very important exception is related to the reaction of bis(benzene) vanadium (which is isoelectronic with [MnCpf ]) with TCNE, which affords a material with unprecedented properties [72]. The amorphous material obtained displays bulk ferromagnetism at room temperature and its even exceeds the decomposition temperature of the sample of about 350 K. The compound is no longer an arene complex as it has an empirical composition corresponding to V(TCNE)2 1/2(CH2C12). 

The physical and chemical properties of various vanadium compounds are shown in Table 3-2. 

The use of inorganic compounds containing vanadium or germanium as a part of chemical ingredients in plating baths enhances the quahty of deposited copper. Most fuU-build electroless baths used today contain either V2O5 or G2O5 to improve the physical properties of deposited copper. 

DuPont s Sclair process was extremely important technology which was introduced in the 1960s, as it offered commercial ethylene copolymers at densities as low as 0.916 g/cc with improved physical properties over comparable polyethylene resins produced with the high-pressure process. In addition, DuPont scientists also developed improved catalysts for the Sclair process based on vanadium compounds that produced homogeneous branching distribution of the short-chain branches introduced along the polymer backbone by incorporation of a comonomer such as 1-butene into the polymer structure. 

Besides the use of vanadium-based catalysts, a wide variety of other catalyst compositions were reported. A recent review focussed on FeSbO based catalysts promoted by appropriate additives as suitable for the ammoxidation of alkyl-substituted aromatics and hetero aromatic compounds. A unique preparation method of a fluid-bed catalyst is presented using nitric acid oxidation of antimony trioxide catalyzed with iron ions. The catalysts thus prepared have superior catalytic and physical properties. [78]. In addition, some unique compositions were reported by different research groups. For instance, new ammoxidation catalysts based on rhenium carbonyl cluster complexes containing antimony and bismuth ligands were reported by Adam et al. [79]. Single-site multifunctional catalysts based on [Cu RUj C ] nanocluster anchored to inner walls of mesoporous silica were also used in the ammoxidation of 3P [80]. 

TABLE 3-2. Physical and Chemical Properties of Vanadium and Compounds ... 

Physical and Chemical Properties. The physical and chemical properties of vanadium and its compounds are reasonably well documented (see Tables 3-1 and 3-2). Further information, such as partition coefficients, would be helpful in understanding the transport and transformation of vanadium in the environment. 

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