Maleic anhydride, oxidation 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... 

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 ... 

Waugh et al.131 discussed the selective oxidation of benzene to maleic anhydride on the basis of a detailed study of maleic anhydride and benzene adsorption on a V-Mo oxide catalyst supported on a-Al203. Hydroquinone is found to be an intermediate in this reaction and p-benzoquinone, formed from the hydroquinone, is the main intermediate in the non-selective pathway. The maleic anhydride is observed to be immobile adsorbed and the surface oxidation reaction has a relatively low activation energy. From this the authors conclude that it is not lattice oxygen but weakly bound molecular 02 which is responsible for the selective oxidation and a detailed mechanism, in which use is made of orbital symmetry arguments, is presented. 

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,... 

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

In studying the kinetics of benzene oxidation to maleic anhydride and in order to eliminate diffusion hindrance, Ioffe and Lyubarskii (151) used the flow-circulating method. The rate of this reaction was found to be proportional to benzene concentration to the power of 0.78, and that of high conversion to the power of 0.71. The rate of maleic anhydride oxidation followed a first order equation. Kinetic equations were derived from experimental results ... 

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. 

Oxidation of SO2 for sulfuric acid production Selective catalytic reduction of NO using ammonia [8] Oxidation of benzene to maleic anhydride Oxidation of o-xylene to phthalic anhydride [9] Dehydrogenation of light alkanes to alkenes [10] Ethylene polymerization [11]... 

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... 

Volatile aromatics are starting materials for numerous commercial synthesis processes. In contrast to the other compounds, benzene is relatively stable [43]. Above 650 °C, diphenyl is formed thermally [43]. It is relatively resistant to oxygen. At 400 °-500 °C and 2-3 bar pressure, with a residence time of 0.1 s, it can be oxidized with large quantities of excess air on catalysts (V2O5 on AI2O3) to maleic anhydride [43]. Benzene can be relatively easily hydrogenated to cyclohexane [43]. 

Commercially, maleic anhydride is prepared more cheaply by the catalytic vapour phase oxidation (in the presence of vanadium pentoxide at about 400°) of benzene with atmospheric oxygen ... 

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. 

Benzene-Based Catalyst Technology. The catalyst used for the conversion of ben2ene to maleic anhydride consists of supported vanadium oxide [11099-11-9]. The support is an inert oxide such as kieselguhr, alumina [1344-28-17, or sUica, and is of low surface area (142). Supports with higher surface area adversely affect conversion of benzene to maleic anhydride. The conversion of benzene to maleic anhydride is a less complex oxidation than the conversion of butane, so higher catalyst selectivities are obtained. The vanadium oxide on the surface of the support is often modified with molybdenum oxides. There is approximately 70% vanadium oxide and 30% molybdenum oxide [11098-99-0] in the active phase for these fixed-bed catalysts (143). The molybdenum oxide is thought to form either a soUd solution or compound oxide with the vanadium oxide and result in a more active catalyst (142). 

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. 

Most maleic anhydride production in the United States is based on benzene as feedstock, even though substantial Hterature exists on the use of butenes (132—134). However, the rapidly increasing demand and price for benzene (as high as 620 /t in 1986 versus 310 /t for ethylene) have made benzene (qv) less attractive and butenes a better feedstock. Not only are theoretical yields better, 1.75 kg/kg of butenes compared to 1.26 kg/kg of ben2ene, but less oxygen is required and the oxidation produces less heat, which is critical in reactor design. 

Maleic anhydride is made by oxidation of benzene with air above 350°C (662°F) with V-Mo catalyst in a mnltitiibiilar reactor with 2-cm tubes. The heat-transfer medium is a eutectic of molten salt at 375°C (707°F). Even with small tubes, the heat transfer is so hmited that a peak temperature 100°C (212°F) above the shell side is developed and moves along the tubes. 

Similar approaches are applicable in the chemical industry. For example, maleic anhydride is manufactured by partial oxidation of benzene in a fixed catalyst bed tubular reactor. There is a potential for extremely high temperatures due to thermal runaway if feed ratios are not maintained within safe limits. Catalyst geometry, heat capacity, and partial catalyst deactivation have been used to create a self-regulatory mechanism to prevent excessive temperature (Raghaven, 1992). 

Oxidation of n-hutane to maleic anhydride is becoming a major source for this important chemical. Maleic anhydride could also be produced by the catalytic oxidation of n-butenes (Chapter 9) and benzene (Chapter 10). The principal use of maleic anhydride is in the synthesis of unsaturated polyester resins. These resins are used to fabricate glass-fiber reinforced materials. Other uses include fumaric acid, alkyd resins, and pesticides. Maleic acid esters are important plasticizers and lubricants. Maleic anhydride could also be a precursor for 1,4-butanediol (Chapter 9). 

Other routes to maleic anhydride are the oxidation of n-hutane, a major source for this compound (Chapter 6), and the oxidation of benzene (Chapter 10). 

Benzene oxidation is the oldest method to produce maleic anhydride. The reaction occurs at approximately 380°C and atmospheric pressure. A mixture of V2O5/MO3 is the usual catalyst. Benzene conversion reaches 90%, hut selectivity to maleic anhydride is only 50-60% the other 40-50% is completely oxidized to C02 °... 

The equilibrium between oxepin and benzene oxide created interest in performing Diels-Alder reactions trapping one or both isomeric structures.1 The reaction of maleic anhydride or maleic imide with oxepin and substituted derivatives gives products 1 derived from the addition of the dienophile to the benzene oxide structure.2-l4-126 14 9 156 158 228 231-259... 

For many years the catalytic air oxidation of benzene was the main source of maleic anhydride. Obviously, two carbons from each ring are wasted as carbon dioxide in this process. Although some is still made that way, most modem maleic anhydride plants are based on butane oxidation. Because butane is forecast to be plentiful and low-cost, new routes to four-carbon chemicals from maleic anhydride are under active development. 

Adamska-Rutkowska, D., 1992, An Identification of the Model of the Process for Oxidation of Benzene to Maleic Anhydride , Ph.D. Thesis, Warsaw University of Technology, Warsaw. 

Vaidyanathan and Doraiswamy (1968) studied the kinetics of the gas-phase partial oxidation of benzene (CgHg, B) to maleic anhydride (C4H2O3, M) with m in an integral PFR containing... 

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... 

For many years maleic anhydride (MA) was made from benzene by oxidation and loss of two moles of CO2. Even as late as 1978 83% of maleic... 

Maleic anhydride (2,5-furandione) is obtained as a by-product in the production of phthalic anhydride and by the vapor phase oxidation of butylene or crotonaldehyde. It is also obtained by the dehydration of maleic acid and by the oxidation of benzene. Maleic anhydride is used for the production of unsaturated polyester resin. This reactant, like most reactants, is fairly toxic and should be treated as such. 

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