Vanadium phosphorous oxide catalyst

The Geminox process oxidizes n-butane in air over a vanadium-phosphorous oxide catalyst in a fluid-bed reactor to maleic anhydride, which is then quenched to maleic acid by absorbing it into water. This highly acidic stream is then pumped to two high-pressure fixed-bed hydrogenation reactors containing carbon-supported catalysts to convert maleic acid to BDO. The major product of reaction, a mixture of 1,4-butanediol, tetrahydrofuran (THF), and y-butyrolactone, is then separated by fractional distillation. The yield of... 

Catalysts which can selectively activate the normally un-reactive paraffins have been developed in recent years. The production of maleic anhydride from butane over vanadium-phosphorous-oxide catalysts has received much attention (Eqn. 5), and is beginning to replace the more wasteful production of maleic anhydride from benzene (Eqn. 6) which is still the major feedstock. Maleic anhydride production from butene or butadiene is also possible (Eqn. 7), but cannot compete with the cheaper butane feed. Maleic anhydride is mainly used in the manufacture of unsaturated polyester resins, fumaric acid manufacture, insecticides, and fungicides (Figure 5). ... 

A new process for the partial oxidation of n-butane to maleic anhydride was developed by DuPont. The important feature of this process is the use of a circulating fluidized bed-reactor. Solids flux in the rizer-reactor is high and the superficial gas velocities are also high, which encounters short residence times usually in seconds. The developed catalyst for this process is based on vanadium phosphorous oxides... 

In the process based on n-butane feedstock, vanadium phosphorous oxides (V-P-O) catalysts are mainly used.1010-1012 Processes for the oxidation of low-cost C4 fraction from naphtha cracker consisting mainly of butenes have also been developed.1013,1014 In contrast with benzene oxidation where two carbon atoms are lost in the form of ethylene no carbon is lost in the oxidation of C4 hydrocarbons ... 

In addition to the requirements with respect to size, shape, and mechanical stability, the nature of the active phase also has to be adopted when the same catalyst is applied in different reactor concepts mainly due to differing process conditions. Vanadium phosphorous oxide composed of the vanadyl pyrophosphate phase (VO)2P207 is an excellent catalyst for selective oxidation of H-butane to maleic anhydride [44-47]. This type of catalyst has been operated in, for example, fixed-bed reactors and fluidized-bed-riser reactors [48]. In the different reactor types, different feedstock is applied, the feed being more rich in //-butane (i.e. more reducible) in the riser-reactor technology, which requires different catalyst characteristics [49]. 

Carreon MA, Guliants W. Chapter 6 selective oxidation of n-butane over vanadium-phosphorous oxide. Nanostructured Catalysts Selective Oxidations The Royal Society of Chemistry 2011. p. 141-168. 

PoH G., Resta I., Ruggeii O. and Trifiro F. (1981). The ehemistry of catalysts based on vanadium-phosphorous oxides Note II. The role of the method of preparation, AppL Catal., 1 pp. 393-404. 

Very different catalytic materials have been tested in the selective oxidation of propane, which includes vanadium phosphorous oxide (VPO) catalysts, industrially applied for w-butane oxidation to maleic anhydride. The other catalysts systems include Keggin structure heteropolyoxometalUc compounds (HPCs) and multicomponent mixed oxides (MMOs). These materials have different structure and properties, but have something in common they contain reducible metal 0x0 species. 

Usually, catalysis research for a new reaction starts with investigating systems effective for similar reactions. Therefore, the most obvious choice is the vanadium phosphorous oxide (VPO) catalyst, which is successfully implemented in the industry for -butane oxidation. The reported maleic anhydride selectivity varies from 45 to 65% with -butane conversion of 65% [20,21], VPO is also well known to catalyze selectively O- and N-insertion reaction on aliphatics, methyl aromatics, and methyl heteroaromatics [22,23],... 

The catalyst used in the production of maleic anhydride from butane is vanadium—phosphoms—oxide (VPO). Several routes may be used to prepare the catalyst (123), but the route favored by industry involves the reaction of vanadium(V) oxide [1314-62-1] and phosphoric acid [7664-38-2] to form vanadyl hydrogen phosphate, VOHPO O.5H2O. This material is then heated to eliminate water from the stmcture and irreversibly form vanadyl pyrophosphate, (V(123,124). Vanadyl pyrophosphate is befleved to be the catalyticaHy active phase required for the conversion of butane to maleic anhydride (125,126). 

Under microwave irradiation and applying MCM-41-immobilized nano-iron oxide higher activity is observed [148]. In this case also, primary aliphatic alcohols could be oxidized. The TON for the selective oxidation of 1-octanol to 1-octanal reached to 46 with 99% selectivity. Hou and coworkers reported in 2006 an iron coordination polymer [Fe(fcz)2Cl2]-2CH30H with fez = l-(2,4-difluorophenyl)-l,l-bis[(l//-l,2,4-triazol-l-yl)methyl]ethanol which catalyzed the oxidation of benzyl alcohol to benzaldehyde with hydrogen peroxide as oxidant in 87% yield and up to 100% selectivity [149]. An alternative approach is based on the use of heteropoly acids, whereby the incorporation of vanadium and iron into a molybdo-phosphoric acid catalyst led to high yields for the oxidation of various alcohols (up to 94%) with molecular oxygen [150]. 

Figure 4. X-Ray diffraction patterns for phosphorous-vanadium oxide catalysts prepared by aerosol technique at 600 C, 8 seconds residence time, and 0.8 M V in feed a. Catalyst analyzed by XRD immediately after synthesis, b. catalyst calcined at 450°C in nitrogen for 3 hrs immediately after synthesis, c. Catalyst allowed to stand for 14 days in an air tight container at ambient temperature without calcining.

In this process HCN is produced when methanol reacts with ammonia and oxygen in the presence of an oxide catalyst that contains iron, antimony, phosphorous and vanadium. The reaction occurs in the vapor phase in a fluidized bed reactor with an oxygen-to-methanol molar ratio in the gas phase that is less than 1.6. The process and the catalyst are described in patents that were issued to Nitto Chemical (now Mitsubishi Rayon) during the late 1990 s (European Patent 864,532 Japanese patents 10-167,721, 10-251,012, 11-043,323 US Patent 5,976,482). 

In the synthesizer (fig. 1), the water sample is reacted with calcium carbide in a steel chamber under vacuum conditions to produce acetylene. Any water vapor associated with the evolved acetylene is eliminated by trapping in an iso-propyl alcohol and dry ice bath. Further purification in the acetylene is accomplished by a phosphorous pentoxide-ascarite column. The acetylene is collected as a solid in a liquid nitrogen cooled trap and sublimed directly onto a vanadium oxide catalyst supported by an alumina substrate where polymerization to pure benzene is accomplished. The pure benzene is isolated from the catalyst column by heating at 90 degrees Celsius under vacuum and trapping the pure benzene as a solid in a dry-ice... 

The processes from -butane have been used industrially since the 1970s and the key factor for the success of this technology has been the development of the right catalyst (a vanadium-phosphorous mixed oxide), that is still the only option available in the industry. 

Albonetti, S., Cavani, F., Ligi, S., and Mazzoni G. Vanadium/Phosphorous mixed oxide precursor and catalyst and their preparation, (2002) EP1183101B1 (assigned to Lonza). 

Titanium dioxide catalysts were first described in the 1940s and 1950s, when mixed oxide catalysts were being investigated and used in a number of oxidation reactions. Mixtures of vanadium pentoxide with titanium dioxide gave better operation and longer life as phthalic anhydride demand increased. An early catalyst that did not sinter and clearly increased the stability of vanadium pentoxide was described in a patent as Ti0(V03)2. At about the same time vanadium pentoxide/phosphorous pentoxide mixtures were also being developed for use in maleic anhydride processes. 

The mixed vanadium pentoxide/phosphorous pentoxide (with niobium, copper, lithium promoters) catalyst used by Petrotex was, at the time, a further step change in the catalyst types used for hydrocarbon oxidatiom It also eventually contributed to a better understanding of the catalyst structures used in oxidation reactions. The catalyst must have evolved from the accumulated experience obtained with a variety of mixed oxide catalysts and had a composition similar to that shown in Table 4.8. Distillers patented a molybdenum triox-ide/phosphorous pentoxide catalyst, and the Atlantic Refining Company took out a patent for a vanadium pentoxide/phosphorous pentoxide catalyst specifically for butene-2 oxidation. The vanadiitm pentoxide catalyst gave higher yields. 

Early catalysts for acrolein synthesis were based on cuprous oxide and other heavy metal oxides deposited on inert siHca or alumina supports (39). Later, catalysts more selective for the oxidation of propylene to acrolein and acrolein to acryHc acid were prepared from bismuth, cobalt, kon, nickel, tin salts, and molybdic, molybdic phosphoric, and molybdic siHcic acids. Preferred second-stage catalysts generally are complex oxides containing molybdenum and vanadium. Other components, such as tungsten, copper, tellurium, and arsenic oxides, have been incorporated to increase low temperature activity and productivity (39,45,46). 

The production of maleic anhydride from n-butenes is a catalyzed reaction occurring at approximately 400-440°C and 2-4 atmospheres. A special catalyst, constituted of an oxide mixture of molybdenum, vanadium, and phosphorous, may be used. Approximately 45% yield of maleic anhydride could be obtained from this route ... 

The solids analysis described above can be taken to yet another level by correlating the color measurement to chemical properties. An excellent model system is vanadium pyrophosphate (VPO), which is a well-known catalyst for butane oxidation to maleic anhydride. During the synthesis of the catalyst precursor, solid V2O5 particles are dispersed in a mixture of benzyl alcohol and i-butanol. In this slurry phase, the vanadium is partly reduced. Addition of phosphoric acid leads to a further reduction and the formation of the VPO structure. With a diffuse reflectance (DR) UV-vis probe by Fiberguide Ind., the surface of the suspended solid particles could be monitored during this slurry reaction. Four points can be noted from Figure 4.4 ... 

Chloric acid, in conjunction with catalysts (particularly vanadium pentaoxide), is used for the oxidation of aldonic acids or lactones to the 2-glyculosonic acids. Thus, D-glucono-1,4-lactone (9) and potassium D-galactonate in methanol, in the presence of phosphoric acid and vanadium pentaoxide, are oxidized by chloric acid to methyl D-arabino-2-hexulosonate (10) and methyl D-/yxo-2-hexulosonate, respectively.38 At moderate temperatures in the absence of a catalyst, aldoses, ketoses, and sucrose are inert to the action of chlorates over a several weeks time period 39 bromates in alkaline solution also exert no oxidative action (Scheme 5). 

O Mahony et al. (2004) XPS Vanadium oxides, phosphoric acid Phase formation redox behavior + + n.a. Catalyst synthesis, role of reducing solvent for VPP... 

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