Vanadium pentoxide, manufacture

Oxidation. Benzene can be oxidized to a number of different products. Strong oxidizing agents such as permanganate or dichromate oxidize benzene to carbon dioxide and water under rigorous conditions. Benzene can be selectively oxidized in the vapor phase to maleic anhydride. The reaction occurs in the presence of air with a promoted vanadium pentoxide catalyst (11). Prior to 1986, this process provided most of the world s maleic anhydride [108-31 -6] C4H2O2. Currendy maleic anhydride is manufactured from the air oxidation of / -butane also employing a vanadium pentoxide catalyst. 

Orthophthalic acid is made by the oxidation of naphthalene (1) with H2SCL fuming heated, in the presence of mercuric sulfate —SO2 is also formed and recovered (2 ) with air in the presence of vanadium pentoxide at 450 to 520°C. Orthophthalic acid also is formed when benzene compounds containing carbon ortho-substituted groups are oxidized. Orthophthalic arid is used in the manufacture of indigo and other dyes,... 

The use of certain vanadium compounds as catalysts has been increasing. Vanadium oxy trichloride is a catalyst in making ediylene-propylene rubber. Ammonium metavanadate and vanadium pentoxide aie used as oxidation catalysts, particularly in the production of polyamides, such as nylon, in the manufacture of H>S04 by the contact process, in the production of phdialic and maleic anhydrides, and in numerous other oxidation reactions, such as alcohol to acetaldehyde, anthracene to anthraquinone, sugar to oxalic acid, and diphenylamine to carbazole. Vanadium compounds have been used for many years 111 die ceramics field for enamels and glazes. Colors are produced by various combinations of vanadium oxide and silica, zirconia, zinc, lead, tin, selenium, and cadmium. Vanadium intermediate compounds also are used in the making of aniline Mack used by the dye industry... 

The major industrial use of vanadium is in alloy steels and cast iron, to which it lends ductility and shock resistance. Conunercial production is mainly as the iron alloy ferrovanadium, a tough, high-speed steel containing around 4-5% V. In ferrovanadium manufacture, vanadium pentoxide is reduced in an airtight electric furnace by ferrosilicon. ... 

The solution to this problem was the discovery of certain catalysis (platinum, vanadium pentoxide), which speed up the reaction without affecting the equilibrium. The catalyzed reaction proceeds not in the gaseous mixture, but on the surface of the catalyst, as the gas molecules strike it. In practice sulfur dioxide, made by burning sulfur or pyrite, is mixed with air and passed over the catalyst at a temperature of 400° to 450° C. About 99% of the sulfur dioxide is converted into sulfur trioxide under these conditions. It is used mainly in the manufacture of sulfuric acid. 

In some cases a catalyst consists of minute particles of an active material dispersed over a less active substance called a support. The active material is frequently a pure metal or metal alloy. Such catalysts are called supported catalysts, as distinguished from unsupported catalysts, whose active ingredients are major amounts of other substances called promoters, which increase the activity. Examples of supported catalysts are the automobile-muffler catalysts mentioned above, the platinum-on-alumina catalyst used in petroleum reforming, and the vanadium pentoxide on silica used to oxidize sulfur dioxide in manufacturing sulfuric acid. On the other hand, the platinum gauze for ammonia oxidation, the promoted iron for ammonia synthesis, and the silica-alumina dehydrogenation catalyst used in butadiene manufacture typify unsupported catalysts. 

Some manufacturers think electric cars with vanadium pentoxide batteries are part of the world s transportation future. Drivers would bring these cars into a battery filling station. The worn-out battery would be pumped out and replaced in a matter of minutes. 

Vanadium carbide is manufactured by the carburization of pure vanadium pentoxide (mostly produced from ammonium vanadate) in vacuum at 1700°C. Vanadium carbide exhibits a high hardness, but its brittleness prevents its wide utilization in cemented carbides. In WC-Co alloys, it is added in quantities of < 1% by weight as a particle growth inhibitor. 

Important commercial reactions that are carried out in multistage adiabatic reactors include 1) the oxidation of SO2 to SO3 over a vanadium pentoxide catalyst, which is the key step in sulfuric acid manufacture, and 2) the silver-catalyzed oxidation of methanol to... 

Sulfur Dioxide to Sulfur Trioxide Process. The manufacture of sulfuric acid involves the oxidation of elemental sulfur to SO2, followed by the catalytic oxidation of SO2 to SO3 over vanadium pentoxide. The next step involves the absorption of SO3 with water to form H2SO4. The SO2 oxidation reaction to... 

The import of vanadium by the United States can be split into three different products vanadium-containing materials such as ores, slags, and residues from which the vanadium must still be recovered ferrovanadium and manufactured vanadium compounds (principally vanadium pentoxide). Due to shortages of domestic ore and petroleum residues, imports of the former increased substantially from 1983 to 1987, rising from 58 to 2,264 tons. On the other hand, imports of ferrovanadium have declined from 1,461 tons in 1984 to 422 tons in 1987. Imports of vanadium pentoxide were approximately 400 tons in both 1984 and 1987, despite falling to as low as 63 tons in 1985. In 1986, the top four exporters of vanadium to the United States were Austria, Canada, the Federal Republic of Germany, and the Republic of South Africa (Hilliard 1987). 

Considerable interest has centered around the F.I.A.T. and B.I.O.S. reports of the catalysts used in Germany for phthaJic anhydride manu-facture. The life of the vanadium pentoxide catalyst used for the manufacture of phthalic anhydride at the Ludwigshafen works was over ten years. The Germans were reported to have obtained yields of 1 lb of phthalic anhydride per pound of naphthalene equal to oyer 86 per cent with product purities in the range 97-98 per cent. These German results compare with previously reported results in this country of 80 per cent sdelds and catalyst life of less than one year. 

Vanadium has an abundance in the earth s crust of about 0.2% (Clark, 1975). It is quite eveniy distributed in minerais. A few commerciai deposits contain more than 3% vanadium pentoxide, but normai concentrations are 0.1 - 1% (NAS. 1974). The main sources of vanadium are vanadium suiphide (patronite), carnotite and titanomagnetite ores. Many crude oiis contain considerabie amounts (even about 0.1%) of vanadium, notably those from Venezuela. The ash obtained from burning vanadium-containing oils may have many tens of per cent vanadium. Vanadium can be extracted from fuel ashes. A considerable amount of vanadium production is based on the extraction of converter slag in the steel industry, which can contain 2-10% (Michels, 1973) or even 25% (NAS 1974) vanadium pentoxide. Vanadium is usually manufactured by converting the vanadium minerals to a water- soluble form (Levanto, 1969). 

Maleic anhydride, C4H2O, is manufactured by the oxidation of benzene with excess air over vanadium pentoxide catalyst (Westerlink and Westerterp, 1988). The following reactions occur ... 

The development of the less expensive and less easily contaminated vanadium pentoxide (V2O5) catalyst by BASF in Germany in 1915, combined with increasing demand for concentrated sulfuric acid by the chemical industry, has led to the gradual replacement of the lead-chamber process by the Contact Process. In 1930, sulfuric acid produced by the Contact Process accounted for only 25% of sulfuric acid production, while today nearly all sulfuric acid is manufactured in this way. 

The sulfuric acid industry got a head start in the 1940s due to the invention of vanadium pentoxide as catalyst to convert sulfur dioxide to sulfur trioxide, popularly known as the contact process. This enabled large sulfuric acid plants of high capacity to be built to produce phosphoric acid for the manufacture of phosphatic fertilizers. 

Two important commercial diacids are adipic acid (hexanedioic acid) and phthalic acid (l -benzenedicarboxylic acid). Adipic add is used in the manufacture of nylon 66, and phthalic add is used to make polyesters. The industrial synthesis of adipic acid uses benzene as the starting materiaL Benzene is hydrogenated to cyclohexane, whose oxidation (using a cobalt/acetic add catalyst) gives adipic acid. Phthalic acid is produced by the direct oxidation of naphthalene or xylene using a vanadium pentoxide catalyst. 

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