Maleic anhydride, from benzene

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... 

Although benzene prices have escalated in recent years, a concurrent need for butenes for use in alkylates for motor fuel has also increased and butane prices have also escalated. As a result, a search for alternative feedstocks began and Amoco Chemical Co. commercialized a process in 1977 to produce maleic anhydride from butane. A plant in JoHet came on-stream in 1977 with a capacity of 27,000 t/yr (135,136). No new plants have been built in the United States based on butenes since the commercialization of butane to maleic anhydride technology. In Europe and particularly in Japan, however, where butane is in short supply and needs for butenes as alkylation feed are also much less, butenes may become the dominant feedstock (see Maleic anhydride). 

The activity and selectivity of 19 oxides at 400—450°C were investigated by Germain and Laugier [133], The activities are compared with those for the oxidation of toluene in Fig. 8, and show a linear relationship for the major part of the oxides, the toluene oxidation being approximately twice as fast as the benzene oxidation. The only selective catalysts, i.e. those that produce substantial amounts of benzoquinone and maleic anhydride from benzene, and benzaldehyde and benzoic acid from toluene are the oxides of V, Mo and W. Remarkably, these oxides clearly deviate from the average correlation in Fig. 8 and show a much higher tol-uene/benzene activity ratio (about 10/1). The order of activity, maximum yield of maleic aldehyde and initial selectivity with respect to benzoquinone is the same for these oxides V > Mo > W. 

Unsaturated 1,4-Dicarbonyl Reaction. Bandow et al. [144,145] observed the formation of maleic anhydride from benzene, toluene, and o-xylene possibly arising from the HO-initiated oxidation of the expected 1,4-dicarbonyl (CHO)CH=CH(CHO), i.e ... 

Scheme 6 Preparation of the benzene-maleic anhydride exo-ortho adduct. (From Ref. 39.)...

Both the excited singlet and the triplet state (which can be reached by sensitization or by direct irradiation in a heavy-atom solvent) of the complex first form one bond between benzene and maleic anhydride. From the excited singlet state, a zwitterion is formed that can be trapped by protonation. In the absence of protons, it collapses to the ortho adduct. The species formed from the triplet state... 

In the presence of a second dienophile, the ortho adduct can be trapped. Koltzenburg et al. [43] have added duroquinone to a benzene solution of maleic anhydride and obtained a 1 1 1 adduct formed from benzene, maleic anhydride, and duroquinone. 

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... 

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-... 

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 1. Infrared spectra (KBr) of (A) polyimide prepared by photolysis of benzene sobitions of ii,N -hexarnethylenebistnaleirnide (B) polyimi prepared from benzene-maleic anhydride photoadauct (2) and 1,6-hexanediamine and (C) the N,N -bis(n-...

As cited in Chapter 1, the first example of commercial process using an alkane as feedstock, in substitution of the older process starting from benzene, was the synthesis of maleic anhydride from n-butane. Figure 2.66 briefly recalls the reaction scheme on the model surface of the catalyst (vanadyl pyrophosphate) to evidence the... 

Maleic Anhydride. The preparation of maleic anhydride from C4 hydrocarbons is given by Bretton (10). The preparation of maleic anhydride from benzene is described in Faith, Keyes, and Clark (31). Maleic anhydride is an important by-product in the phthalic anhydride process. 

Polycarboxylic acid anhydrides by oxidation of aromatic compounds, e.g.—phthalic anhydride from naphthalene or o-xylene and also maleic anhydride from benzene... 

There have been notable shifts in raw materials for the manufacture of maleic anhydride and phenol. Made for many years by the oxidation of benzene, maleic anhydride now is made by a catalytic process from butane. The butane process was found to result in lower costs of operation as well as reduced environmental, safety, and health hazards. Another example is the manufacture of phenol, initially made from benzene or chlorobenzene. Subsequently, however, with large supplies of cumene from the catalytic reaction of benzene and propylene, production came to be dominated by cumene-derived phenol, which, requires a lower capital investment and offers reduced operating expenses as well as reduced environmental and safety problems. A novel... 

Economic data concerning the production of maleic anhydride from benzene, n-butane and olefinic C4 cuts are given in Table 13.4. 

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 (MA) is an important raw material in the production of alkyd and polyester resins. It was first obtained by Nikolas Louis Vauquelin in 1817, by heating maleic acid to over 140 °C. In 1905, Richard Kempf obtained maleic acid by the oxidation of benzoquinone. The first patents covering the production of maleic anhydride from benzene originate from John M. Weiss and Charles R. Downs in 1918. The oxidation of benzene remains a feasible route to maleic anhydride even today, although since around 1975, n-butane and n-butylene have increasingly replaced benzene as raw materials. n-Butane and n-butylene are available as co-products in steam cracking of naphtha and from natural gas condensates. 

Since in the oxidation of benzene to maleic anhydride, two carbon atoms are lost as CO2, attempts were made early on to produce maleic anhydride from C4 hydrocarbons. With the development of the petrochemical industry, large quantities of C4-cuts became available, from which butene and, by hydrogenation, butane, could be recovered. The use of benzene is in decline, particularly in the USA, since benzene is now produced there, among other routes, by dealkylation of toluene, whereas C4-components are readily available from cat-cracker and ethylene plants. 

Syntheses have been reported of barrelene (505) and of Nenitzescu s hydrocarbon (503) on a reasonable scale and without some of the difficulties that attend the previously published routes." " The preparation of (503) is of central importance, it being obtained by the oxidative bisdecarboxylation of the cyclo-octatetraene-maleic anhydride Diels-Alder adduct (502) with dicarbonylbis(triphenylphosphine)-nickel in diglyme at reflux. Cycloaddition of (503) to 2,5-dimethyI-3,5-diphenyl-cyclopentadienone in hot benzene afforded (504) and its endo-isomer. Photolysis of (504) yielded (505) in 24% yield from cyclo-octatetraene. The thermally labile benzene-maleic anhydride [4 + 2] cycloadduct (506) was obtained in similar fashion from (502). A review of the mechanisms of pyrolysis of (503) and a number of isomers and benzo-fused (CH) derivatives (collectively termed Nenitzescu s hydrocarbons) has appeared." ... 

A reaction related to cleavage is aromatic ring degradation. Phthalic anhydride used to be prepared from naphthalene, and maleic anhydride from benzene, with air and V2O5 catalyst, losing 2 carbon atoms as CO2. More modern processes use o-xylene and butadiene (or -butane) respectively. However, the analogous formation of quinolinic (pyridine-2,3-dicarboxylic) acid from quinoline is still practised. Hypochlorite [94], hypochlorite or chlorite/Ru catalyst [95], or simply alkaline H2O2 [96] can be used. 

Table 14J2. Different supports for maleic anhydride from benzene catalyst.

The V-Mo-O oxides are well-known industrial catalysts for the synthesis of acrylic acid from acrolein and maleic anhydride from benzene more recently, V-P-0 systems are being utilized for maleic anhydride production from -butane. The V20s/Ti02 combination was employed for phthalic acid production from o-xylene. V-Fe-O catalyzes oxidation of polycyclic aromatic hydrocarbons to dicarboxylic acids and quinones. Methyl formate is produced by the oxidation of methanol over V-Ti-0 catalysts [58]. For many of these processes, it has been experimentally proved that the catalytic reaction follows a Mars-van Krevelen mechanism. The surface coverage with active oxygen 0 in the steady state of the redox reaction following Mars-van Krevelen mechanism is given by... 

B.5 Production of Maleic Anhydride from Benzene. Unit 600 B.6 Ethylene Oxide Production. Unit 700... 

The reactor effluent, Stream 7—containing small amounts of unreacted benzene, maleic anhydride, quinone, and combustion products—is cooled in E-603 and then sent to an absorber column, T-601, which has both a reboiler and condenser. In T-601, the vapor feed is contacted with recycled heavy organic solvent (dibutyl phthalate). Stream 9. This solvent absorbs the maleic anhydride, quinone, and small amounts of water. Any water in the solvent leaving the bottom of the absorber, T-601, reacts with the maleic anhydride to form maleic acid, which must be removed and purified from the maleic anhydride. The bottoms product from the absorber is sent to a separation tower, T-602, where the dibutyl phthalate is recovered as the bottoms product. Stream 14, and recycled back to the absorber. A small amount of fresh solvent. Stream 10, is added to account for losses. The overhead product from T-602, Stream 13, is sent to the maleic acid column, T-603, where 95 mol% maleic acid is removed as the bottoms product. 

Ma.leic Anhydride. The largest chemical use for / -butane is as feedstock for maleic anhydride. A dilute air—butane mixture is passed over a vanadium—phosphoms catalyst 400—500°C to produce maleic anhydride [108-31-6] in good yield. Formerly benzene was used as feedstock, but in the last few years nearly all maleic anhydride in the United States, and an increasing proportion worldwide, is made from butane. 

Capacities of maleic anhydride faciUties worldwide are presented in Table 7. The switch of feedstock from benzene to butane was completed in the United States in 1985, being driven by the lower unit cost and lower usage of butane in addition to the environmental pressures on the use of benzene. Worldwide, the switch to butane is continuing with 58% of the total world maleic anhydride capacity based on butane feedstock in 1992. This capacity percentage for butane has increased from only 6% in 1978. In 1992, 38% of the total world maleic anhydride capacity was based on benzene feedstock and 4% was derived from other sources, primarily phthaUc anhydride by-product streams. 

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. 

Prior to 1975, benzene was catalytically oxidized to produce maleic anhydride, an intermediate in synthesis of polyester resins, lubricant additives, and agricultural chemicals. By 1986 all commercial maleic anhydride was derived from oxidation of / -butane. It is expected that / -butane will remain the feedstock of choice for both economic and environmental reasons. 

Biphenyl [92-52-4] M 154.2, m 70-71 , b 255 , d 0.992. Crystd from EtOH, MeOH, aq MeOH, pet ether (b 40-60 ) or glacial acetic acid. Freed from polar impurities by passage through an alumina column in benzene, followed by evapn. A in CCI4 has been purified by vac distn and by zone refining. Treatment with maleic anhydride removed anthracene-like impurities. Recrystd from EtOH followed by repeated vacuum sublimation and passage through a zone refiner. [Taliani and Breed Phys Chem 88 2351 1984.]... 

Maleic anhydride [108-31-6] M 98.1, m 54 , b 94-96 /20mm, 199 /760mm. Crystd from benzene, CHCI3, CH2Cl2or CCI4. Sublimed under reduced pressure. [Skell et al. J Am Chem Soc 108 6300 7956.]... 

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