Maleic anhydride production, vanadium

Maleic anhydride production. The oxidation of benzene to maleic anhydride over a vanadium pentoxide electrode has been studied by Pizzini et... 

The first industrial plant using n-butane to manufacture maleic anhydride was started up by Monsanto in 1984. At the time, 20 per cent of the maleic anhydride production capacity of this company switched from benzene to butane. Since then, three other manufacturers in the United States (Amoco, Ashland and Denka Chemical), and two in Western Europe (Bayer and Huh) have followed a similar procedure, so that ail maleic anhydride produced today in the United States is based on butane feedstock and nearly 50 per cent of worldwide installed capacity operates by this method. The n-butane is oxidized in the vapor phase, in a multi-tube reactor, on a fixed bed of catalyst based on phosphorus, vanadium and iron, deposited on a silica/alumina support... 

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). ... 

Maleic anhydride production. The oxidation of benzene to maleic anhydride over a vanadium pentoxide electrode has been studied by Pizzini et ai 90,91 Unfortunately, the quantities of benzene and maleic anhydride were not determined experimentally. Breckner et al. have studied the partial oxidation of butene to produce maleic anhydride over a vanadium phosphate catalyst. Reaction rate and oxygen activity were monitored in order to correlate catalyst selectivity with oxygen activity. The selectivity of the catalyst was found to increase as the oxygen activity of the catalyst decreased. Both the catalyst reactivity and oxygen activity were found to be dependent upon prior treatments. 

Maleic anhydride and the two diacid isomers were first prepared in the 1830s (1) but commercial manufacture did not begin until a century later. In 1933 the National Aniline and Chemical Co., Inc., installed a process for maleic anhydride based on benzene oxidation using a vanadium oxide catalyst (2). Maleic acid was available commercially ia 1928 and fumaric acid production began in 1932 by acid-catalyzed isomerization of maleic acid. 

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). 

Butane-Based Fixed-Bed Process Technology. Maleic anhydride is produced by reaction of butane with oxygen using the vanadium phosphoms oxide heterogeneous catalyst discussed earlier. The butane oxidation reaction to produce maleic anhydride is very exothermic. The main reaction by-products are carbon monoxide and carbon dioxide. Stoichiometries and heats of reaction for the three principal reactions are as follows ... 

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. 

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 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 oxidation of butane (or butylene or mixtures thereof) to maleic anhydride is a successful example of the replacement of a feedstock (in this case benzene) by a more economical one (Table 1, entry 5). Process conditions are similar to the conventional process starting from aromatics or butylene. Catalysts are based on vanadium and phosphorus oxides [11]. The reaction can be performed in multitubular fixed bed or in fluidized bed reactors. To achieve high selectivity the conversion is limited to <20 % in the fixed bed reactor and the concentration of C4 is limited to values below the explosion limit of approx. 2 mol% in the feed of fixed bed reactors. The fluidized-bed reactor can be operated above the explosion limits but the selectivity is lower than for a fixed bed process. The synthesis of maleic anhydride is also an example of the intensive process development that has occurred in recent decades. In the 1990s DuPont developed and introduced a so called cataloreactant concept on a technical scale. In this process hydrocarbons are oxidized by a catalyst in a high oxidation state and the catalyst is reduced in this first reaction step. In a second reaction step the catalyst is reoxidized separately. DuPont s circulating reactor-regenerator principle thus limits total oxidation of feed and products by the absence of gas phase oxygen in the reaction step of hydrocarbon oxidation [12]. 

The manufacture of phthalic anhydride (world installed capacity ca. 4.4 Mt/a) has several points of similarity to that of maleic anhydride in that there are two alternative feedstocks and a large amount of heat is released. The first process, introduced by BASF at the end of 19 century, was based on the liquid phase oxidation of naphthalene catalyzed by mercury salts. It was later replaced by the cleaner gas phase process, carried out over vanadium and molybdenum oxides. Naphthalene was supplied by coal tar distillation and was used exclusively until the end of 1950s when u-xylene, of petrochemical origin, became an abundantly available feedstock (Equation 36). A few production units however can use either feedstock, taking advantage of price fluctuations in coke plants (naphthalene) and in refineries (u-xylene). 

Vanadium phosphates have been established as selective hydrocarbon oxidation catalysts for more than 40 years. Their primary use commercially has been in the production of maleic anhydride (MA) from n-butane. During this period, improvements in the yield of MA have been sought. Strategies to achieve these improvements have included the addition of secondary metal ions to the catalyst, optimization of the catalyst precursor formation, and intensification of the selective oxidation process through improved reactor technology. The mechanism of the reaction continues to be an active subject of research, and the role of the bulk catalyst structure and an amorphous surface layer are considered here with respect to the various V-P-O phases present. The active site of the catalyst is considered to consist of V and V couples, and their respective incidence and roles are examined in detail here. The complex and extensive nature of the oxidation, which for butane oxidation to MA is a 14-electron transfer process, is of broad importance, particularly in view of the applications of vanadium phosphate catalysts to other processes. A perspective on the future use of vanadium phosphate catalysts is included in this review. 

Maleic anhydride (MA) is an important intermediate in the production of chemicals such as unsaturated polyester resins, lube oil additives, maleic copolymers and others [124]. Currently, MA is predominantly produced by the oxidation of butane, and all industrial catalysts for this reachon are based on vanadium phos-... 

Under extreme conditions, the benzene ring can be oxidized to other products. Maleic anhydride is prepared industrially by passing a mixture of benzene and air over a vanadium pentoxide catalyst t 420 "C,... 

The abundance and low cost of light alkanes have generated in recent years considerable interest in their oxidative catalytic conversion to olefins, oxygenates and nitriles in the petroleum and petrochemical industries [1-4]. Rough estimates place the annual worth of products that have undergone a catalytic oxidation step at 20-40 billion worldwide [4]. Among these, the 14-electron selective oxidation of -butane to maleic anhydride (2,5-furandione) on vanadium-phosphorus-oxide (VPO) catalysts is one of the most fascinating and unique catalytic processes [4,5] ... 

P6 14b The production of maleic anhydride by the air oxidation of benzene was recently studied using a vanadium pentoxide catalyst [Chem. Eng. Set.. 43, 1051 (1988)]. The reactions that occur are ... 

We conclude therefore, that the Nb-Ti-V-P-oxide catalyst investigated is relatively active for the oxidation of paraffins, since it has a V/P ratio of only 1/12 as compared to a 1/1 ratio for (VO)2P207. Of course, we had hoped that the V in the NASICON structure would be sufficiently site isolated to yield products less oxidized than maleic anhydride from n-butane. However, unfortunately that does not appear to be the case. One explanation for this might be that there are still too many adjacent V atoms, i.e., (V-0-V) moieties, where n > 0. Nonetheless, the NASICON structure provides for some desired V site isolation, however, apparently not complete and hence not sufficient to achieve our desired catalytic goal. Another observed fact is, that the Nb-Ti-V-P-oxide under investigation shows an amorphous overlayer via TEM which is enriched in vanadium. The (V/P)s ,face > (V/P)pa icie- One can reason that at the temperature of 900 °C required to obtain the NASICON structure, the more... 

Vanadium-phosphorus oxides are known as the effective catalysts for the production of maleic anhydride by oxidation of n—butane [1—3]. Especially a crystalline (V0)2P20 is claimed to be the active and selective phase [4,5], though some research groups insist that VOPO4 plays an important role [6]. 

One of the most industrially important reactions using vanadium pentoxide(V205) catalyst is the partial oxidation of 1-butene to maleic anhydride [1]. Partial oxidation reactions are inherently unselective and often make by-products of little or no value. Oxygen-rich feeds result in low product selectivities and high hydrocarbon conversions [2]. Because partial oxidation and total oxidation always proceed competitively, the selectivity of maleic anhydride from 1-butene is low. Though fixed bed reactors or fludized bed reactors have been used for partial oxidation for the past 30 years, the selectivity of maleic anhydride has not been obtained higher than 69% [3]. Some attempts have been reported on a new type of reactor to overcome the above limit. This is a membrane reactor which offers some advantages. A membrane reactor plays a... 

Vanadium phosphates (VPO) of different structure are suitable precursors of veiy active and selective catalysts for the oxidation of C4-hydrocarbons to maleic anhydride [e.g. 4] as well as for the above mentioned reaction [5,6]. Normally, VOHPO4 Va H2O is transformed into (V0)2P207 applied as the n-butane oxidation catalyst. Otherwise, if VOHPO4 V2 H2O is heated in the presence of ammonia, air and water vapour a-(NH4)2(V0)3(P207)2 as XRD-detectable phase is formed [7], which is isostructural to a-K2(V0)3(P207)2. Caused by the stoichiometry of the transformation reaction (V/P = 1 V/P = 0.75) (Eq. 2) and the determination of the vanadium oxidation state of the transformation product ( 4.11 [7]) a second, mixed-valent (V 7v ) vanadium-rich phase must be formed. 

Patent claims have been made for the formation of benzene and maleic anhydride with benzoquinone as a by-product by the oxidation of naphthalene.2 For the formation of benzene an example is given in which a mixture of air and naphthalene vapor are passed over a vanadium oxide catalyst at 400° C., the reaction products cooled to 380° C. and then passed over a catalyst containing the oxides of cadmium and aluminum. For the formation of maleic anhydride a mixture of air and naphthalene vapor... 

The first process which employed n-butenes to manufacture maleic anhydride was the Petrotex process in the United States in the early 1950s. At present, however, only Japan still uses this feed for about 35 per cent of its production, amounting to about 5 per cent of worldwide installed capacity. The process is carried out. with the steam-cracked naphtha C4 cut, rid of butadiene and isobutene, and containing approximately 90 per cent weight of i-butene and as and trans 2-butenes and 10 per cent butanes. The catalyst is a mixture of molybdenum, vanadium and phosphorus oxides. 

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