Production of Maleic Anhydride

Production of maleic anhydride by oxidation of / -butane represents one of butane s largest markets. Butane and LPG are also used as feedstocks for ethylene production by thermal cracking. A relatively new use for butane of growing importance is isomerization to isobutane, followed by dehydrogenation to isobutylene for use in MTBE synthesis. Smaller chemical uses include production of acetic acid and by-products. Methyl ethyl ketone (MEK) is the principal by-product, though small amounts of formic, propionic, and butyric acid are also produced. / -Butane is also used as a solvent in Hquid—Hquid extraction of heavy oils in a deasphalting process. 

Reduction. Heterogeneous catalytic reduction processes provide effective routes for the production of maleic anhydride derivatives such as succinic anhydride [108-30-5] (26), succinates, y-butyrolactone [96-48-0] (27), tetrahydrofuran [109-99-9] (29), and 1,4-butanediol [110-63-4] (28). The technology for production of 1,4-butanediol from maleic anhydride has been reviewed (92,93). 

Process Technology Evolution. Maleic anhydride was first commercially produced in the early 1930s by the vapor-phase oxidation of benzene [71-43-2]. The use of benzene as a feedstock for the production of maleic anhydride was dominant in the world market well into the 1980s. Several processes have been used for the production of maleic anhydride from benzene with the most common one from Scientific Design. Small amounts of maleic acid are produced as a by-product in production of phthaHc anhydride [85-44-9]. This can be converted to either maleic anhydride or fumaric acid. Benzene, although easily oxidized to maleic anhydride with high selectivity, is an inherently inefficient feedstock since two excess carbon atoms are present in the raw material. Various compounds have been evaluated as raw material substitutes for benzene in production of maleic anhydride. Fixed- and fluid-bed processes for production of maleic anhydride from the butenes present in mixed streams have been practiced commercially. None of these... 

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). 

Data for the production and sales of maleic anhydride and fumaric acid ia the United States between 1979 and 1992 are shown ia Table 5. Production of maleic anhydride during this time grew - 2% on average per year. Production of fumaric acid has declined during the same period as customers have switched to the less cosdy maleic anhydride when possible. All production of maleic anhydride in the United States in 1992 was from butane-based plants which used fixed-bed reactor technology as shown in Table 6. The number of fumaric acid producers has been reduced considerably since the early 1980s with only two producers left in the United States in 1992 as shown in Table 6. Pfizer shut down its fumaric acid plant at the end of 1993. However, Bartek of Canada will start up an expanded fumaric acid faciUty to supply the North American market for both their own and Huntsman s requirements. 

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 catalysts that allow the production of maleic anhydride from n-butane with high selectivity, like (V0)2P207, are characterized by a strong acidity, that, like a strong basicity, favors the decomposition of alkoxides to give the olefin and the diene. The catalysts that allow the production of maleic anhydride, either from n-butane or from butenes and butadiene, necessarily have particular sites that allow the insertion of oxygen atoms in the 1,4-position of butadiene. These sites are definitely absent on combustion catalysts. 

Acid Curing. Urea-formaldehyde resins and resol-phenol-formaldehyde resins can be acid-cured by wastes from the production of maleic anhydride [1902]. The waste from the production of maleic anhydride contains up to 50% maleic anhydride, in addition to phthalic anhydride, citraconic anhydride, benzoic acid, o-tolulic acid, and phthalide. The plugging solution is prepared by mixing a urea-formaldehyde resin with a phenol-formaldehyde resin, adding the waste from production of maleic anhydride, and mixing thoroughly. 

Development of the third class, i.e. unsaturated polyester resins, remained rather slow until the late 1930s, but after commercial production of maleic anhydride by catalytic oxidation of benzene began in 1933, maleic anhydride and fumaric acid rapidly became the most important sources of unsaturated groups in polyesters. The mechanism of drying of these resins on their own and with the addition of drying oils (i.e. unsaturated compounds such as linseed oil) was... 

As is often said, the simplest unsaturated polyester resin (UPR) is the condensation product of maleic anhydride and propylene glycol dissolved in styrene. 

V-P oxides are known to be efficient for the production of maleic anhydride (abbreviated as MA) from n-butane (1-3). A single-phase (VO2P2O7 has been inferred to be the active catalyst phase (4-6). In addition, the catalytic properties of (VO)2P207 varied depending on the microstructure of (VO)2P207 particles (7,8). Some claimed that the... 

Maleic Anhydride. Gas-phase catalytic oxidation of benzene or n-butane is the principal process for the industrial production of maleic anhydride.973 996-999 Until the 1970s commercial production was based predominantly on benzene. Because of its more favorable economics, a switch to butane as an alternative feedstock has taken place since then.966,999-1002 At present almost all new facilities use n-butane as the starting material. Smaller quantities of maleic anhydride may be recovered as a byproduct of phthalic anhydride manufacture (about 5-6%).1003,1004... 

The low cost of light alkanes and the fact that they are generally environmentally acceptable because of their low chemical reactivity have provided incentives to use them as feedstock for chemical production. A notable example of the successful use of alkane is the production of maleic anhydride by the selective oxidation of butane instead of benzene (7). However, except for this example, no other successful processes have been reported in recent years. A potential area for alkane utilization is the conversion to unsaturated hydrocarbons. Since the current chemical industry depends heavily on the use of unsaturated hydrocarbons as starting material, if alkanes can be dehydrogenated with high yields, they could become alternate feedstock. 

The gas phase oxidation of benzene with air is an important process for the production of maleic anhydride, which is the major partial oxidation product, besides products of complete oxidation. By-products are benzo-quinone, in particular at low conversion, and fumaric acid which is formed at the high conversion levels used in industrial installations [28]. Only traces of phenol and other by-products are formed. The important catalysts are based on V2Os and a maximum yield of 60—80% maleic anhydride is obtained at 350—500° C. 

A new stereoselective synthesis of 1,2,3-trisubstituted cyclopentanes based on the Wag-ner-Meerwein rearrangement of a 7-oxabicyclo[2.2.1]heptyl 2-cation starts with the Diels-Alder product of maleic anhydride and a furan (78TL2165, 79TL1691). The cycloadduct was hydrogenated and subjected to methanolysis. The half acid ester (47) was then electrolyzed at 0 °C to generate a cationic intermediate via the abnormal Kolbe reaction (Hofer-Moest reaction). Work-up under the usual conditions provided the 2-oxabicyclo[2.2.1]heptane (48) in 83% yield. Treatment of this compound in turn with perchloric acid effected hydrolysis of the ketal with formation of the trisubstituted cyclopentane (49) in nearly quantitative yield (Scheme 11). Cyclopentanes available from this route constitute useful... 

Series reactions also occur in oxidation processes where the required product may oxidize further. An example is the production of maleic anhydride from the oxidation of benzene. In this case, the maleic anhydride can be oxidized further to carbon dioxide and water. Another example of a series reaction occurs in the biochemical reaction in which Pseudomonas ovalis is used to convert glucose to gluconic acid via gluconolactone in batch culture. This first order reaction is represented by... 

Maleic anhydride is widely used in polyester resins, agricultural chemicals and lube additives. The growth rate of its production is currently 7-9 percent per year world-wide. In the U.S. the expected consumption by 1983 is 223,000 tons per year ( 5). Conventionally, the production of maleic anhydride via heterogeneous catalytic oxidation of benzene is performed in fixed bed reactors. Rapid increase in benzene prizes and tight benzene-emission control standards caused intense investigations in alternative feedstocks like n-butenes (6), butane ( 5) and the C,-fraction of naphtha crackers (7). As for these alternative feedstocks... 

Figure 1. Various feedstocks used for the production of maleic anhydride. Right, feedstock and left, product.

The C,-fraction of naphtha crackers is used as a feedstock in the Mitsubishi fluid bed process for the production of maleic anhydride. This process was commercialized in 1970. Many data related to this process including the catalyst screening, laboratory experiments, pilot plant design, reactor behaviour and the development of higher selectivity catalysts may be found in the patent literature (12-17).The patents thus give a nearly complete picture of the scale-up process. The data have been used in the present investigation to test the fluid bed reactor model. 

A higher atom and mass efficiency is desirable when comparing alternative reaction choices. A clear example of this is the production of maleic anhydride (MA) starting from either benzene or n-butane.72 Benzene or w-butane is partially oxidized in the vapor phase in the presence of air and a solid catalyst at high temperature and pressure. 

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. 

Type of Reaction and Application. An increased emphasis on gas-solid reactions has been evident for about a decade. Three of the papers in this symposium treat gas-solid reactions, two (13,18) dealing with coal combustion and the other (11) with catalyst regeneration. Of the four papers which consider solid-catalysed gas-phase reactions, one (15) deals with a specific application (production of maleic anhydride), and one (12) treats an unspecified consecutive reaction of the type A B C the other two (14,16) are concerned with unspecified first order irreversible reactions. The final paper (17) considers a relatively recent application, fluidized bed aerosol filtration. Principles of fluid bed reactor modeling are directly applicable to such a case Aerosol particles disappear by adsorption on the collector (fluidized) particles much as a gaseous component disappears by reaction in the case of a solid-catalysed reaction. 

Simulation of a Fluidized Bed Reactor for the Production of Maleic Anhydride... 

The production of maleic anhydride by the catalytic oxidation of benzene is an established industrial process. While hydrocarbons are often suggested as a feedstock, it has been pointed out recently by De Maio (1) that they are an alternative but not necessarily a substitute. The benzene oxidation is done commercially in fixed bed reactors and, because of its exothermicity, is difficult to control in any optimal sense. The process is thus a natural candidate for a fluidized-bed reactor. The reaction has been studied in both fixed bed (2, 3) and fluidized bed (4-7) reactors. These studies, with the exception of that of Kizer et al (7) do not give sufficient information for simulation purposes. The availability of the reaction data of Kizer et al and the kinetic studies of Quach et al ( ) using a similar catalyst suggested the possibility of simulating the process. 

Maleic anhydride is used as a chemical intermediate in the synthesis of fumaric and tartaric acids, certain agricultural chemicals, resins in numerous products, dye intermediates and pharmaceuticals [2]. It is primarily used as a co-monomer for unsaturated polyester resins, which are used in the production of bonding agents for plywood manufacture and when mixed with glass fibres for reinforced plastics. Annual production of maleic anhydride is estimated to be over one million tormes [3]. 

The structure has been determined by XRD and consists of edge-sharing VO5 units linked by pyrophosphate tetrahedra (Figure 12.2). This is viewed as the active surface for most of the proposed mechanisms. Here we will discuss several of the mechanisms thought to account for the production of maleic anhydride, which have been debated in the literature. 

Bergman and Frisch [7] disclosed in 1966 that selective oxidation of n-butane was catalyzed by the VPO catalysts, and since 1974 n-butane has been increasingly used instead of benzene as the raw material for maleic anhydride production due to lower price, high availability in many regions and low environmental impact [8]. At present more than 70 % of maleic anhydride is produced from n-butane [6]. However, productivity from n-butane is lower than in the case of benzene due to lower selectivities to maleic anhydride at higher conversions and somewhat lower feed concentrations (< 2 mol. %) used to avoid flammability of a process stream. Under typical industrial conditions (2 mol. % n-butane in air, 673-723K, and space velocities of 1100-2600 h ) the selectivities [9] for fixed-bed production of maleic anhydride from n-butane are 67-75 mol. % at 70-85 % n-butane conversion [10]. Another unique feature of the VPO catalysts is that no support is used in partial oxidation of n-butane.Many studies of n-butane oxidation on the VPO catalysts indicated that crystalline vanadyl(IV) pyrophos-... 

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 ... 

The success of FCC encouraged applications of the fluidized catalyst reactor to other catalytic reactions. Successful applications can be found in fluid catalytic reforming, production of alkyl chloride by oxychlorina-tion, production of phthalic anhydride, acrylonitrile synthesis by ammox-idation, and production of maleic anhydride. 

Another example is the production of maleic anhydride by Mitubishi Chemical Industries, Ltd. in 1970, which is oxidaticm of BB-fraction. Synthesis of maleic anhydride from butylene is a typical consecutive reaction, and it was considered difficult to get high yield by the use of fluid beds. However, it is highly exothermic and application of fluid beds is preferable. 

Supported vanadla used to promote the selective oxidation of hydrocarbons. Is another example. Vanadia with or without promoters, may be supported on silica (naphthalene oxidation [38]), on tltanla o-xylene oxidation [39]) or on a-alumlna (benzene oxidation [ AO]). It was believed that supports should have open porosity (and associated lower surface area) in order to minimise over oxidation to carbon oxides. However, it was shown that reasonably high activities and selectivitles could be obtained over vanadla supported on high surface area material and it was suggested that low selectivity was, in fact, primarily associated with high acidity on the support [AI]. In agreement with this, vanadla supported on 7-alumina shoved zero selectivity for the production of maleic anhydride from benzene If this Is the case, then a high surface area support with minimal acidity would be desired,... 

Figure 5.4. Comparison of energy use among alternatives for the production of maleic anhydride from n-butane. (Source BRIDGES, 2001.)...

Use Polymer and alkylate gasoline polybutenes butadiene intermediate for C4 and C5 aldehydes, alcohols, and other derivatives production of maleic anhydride by catalytic oxidation. 

Derivation Esterification of Diels-Alder condensation product of maleic anhydride and cyclopenta-diene. 

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