Vanadium pentoxide molybdenum trioxide

Wenda, E. 1985. Phase diagram of vanadium pentoxide-molybdenum trioxide-silver oxide. I. Phase diagram of vanadium pentoxide-silver oxide system. J. Therm. Anal. 30 879-887. 

Another kind of anti hydroxylation is the reaction of alkenes with hydrogen peroxide in the presence of vanadium pentoxide, molybdenum trioxide, selenium dioxide, and especially tungsten trioxide (tungstic acid) [131, 144]. Cyclohexene is thus converted into DL-/rarts-l,2-cyclohex-anediol [131],... 

To obtain a high yield, it is important to use the right catalyst and the right material for containing the catalyst. With vanadium pentoxide in pyrex tubes, the yield is only 25 percent of the input furfural, but with a vanadium pentoxide/molybdenum trioxide/iron molybdate catalyst in nickel tubes, the yield is in the order of 75 percent. Interestingly, the best yields are obtained when the catalyst, prepared from appropriate ammonium salts, is cured with air at 300 °C in situ, and when it is then used directly at the reaction temperature of 270 °C without allowing it to cool down. 

By 1955, Montedison had published sales literature to describe their MAT 5 catalyst which was still based on supported vanadium pentoxide/molybdenum trioxide. The composition of MAT 5 is shown in Table 4.7. A life of between two and three years was claimed, depending on the poisons present in the benzene used, before the pass yield fell from 72% to about 65%. Decreased selectivity may also have depended on the amount of molybdenum lost at the higher operating temperature required to maintain conversion. 

Aluminium oxide, arsenic trioxide, bismuth trioxide, calcium oxide, chromic oxide, lanthanum oxide, lead dioxide, magnesium oxide, manganese dioxide, molybdenum trioxide, phosphorus pentoxide, stannic oxide, sulfur dioxide (explodes), tantalum pentoxide, tungsten trioxide, vanadium pentoxide. 

Lithium is used to reduce metallic oxides in metallurgical operations, and the reactions, after initiation at moderate temperatures, are violently exothermic and rapid. Chromium(III) oxide reacts at 185°C, reaching 965° similarly molybdenum trioxide (180 to 1400°), niobium pentoxide (320 to 490°), titanium dioxide (200-400 to 1400°), tungsten trioxide (200 to 1030°), vanadium pentoxide (394 to 768°) also iron(II) sulfide (260 to 945°), and manganese tclluridc (230 to 600°C)... 

Metal Oxides. Reduction of metal oxides such as chromium(III) oxide, molybdenum trioxide, niobium pentoxide, tungsten trioxide, and vanadium pentoxide is violently exothermic and rapid.9... 

Commercial Metal Oxide SCR Catalysts. In commercial metal oxide SCR catalysts, Ti02 (in the anatase form) is used as high surface area carrier to support the active components, that is, vanadium pentoxide and tungsten trioxide (or molybdenum trioxide). The choice of Ti02-anatase as the best support for SCR catalysts relies on two main reasons ... 

Up to about 1945 the typical naphthalene oxidation catalyst was fused vanadium pentoxide, sometimes combined with molybdenum trioxide, on an inert support. At that time US production of phthalic anhydride was probably less than 60,000 tonnes year and catalyst quality was not very important. 

The first commercial production unit was built by the National Aniline and Chemical Company, part of the Barrett Company, in 1933. However, most of the maleic anhydride used at that time was supphed from phthalic anhydride plants, which produced about 5-10% as a by-product. Demand for maleic anhydride was still low during the 1940s. At that time two typical catalysts were available. One contained 12% vanadium pentoxide/4% molybdenum trioxide supported on a-alumina, while the other contained 10% vanadium pentoxide moderated with less than 1% of lithimn sulfate/sodium sulfate, also supported on a-alumina. The alkali sulfate moderated catalyst was, however, sensitive to sulfur poisons in the benzene feed. 

Weiss and Downs described the use of vanadium pentoxide for the catalytic oxidation of toluene and naphthalene. Subsequently, Graver suggested a mixed oxide catalyst derived from uranium oxide and molybdenum trioxide in molar ratios ranging from 3-13 1. Copper oxide was also suggested as a possible promoter. When using the vanadium pentoxide catalyst, benzoic acid was the main product at temperatures below 400°C, with some benzaldehyde formed at higher temperatures. Selectivity was only about 50% at 5% conversion. 

---