Benzene catalytic oxidation

In the dyestuff industry, anthraquinone still ranks high as an intermediate for the production of dyes and pigments having properties unattainable by any other class of dyes or pigments. Its cost is relatively high and will remain so because of the equipment and operations involved in its manufacture. As of May 1991, anthraquinone sold for 4.4/kg in ton quantities. In the United States and abroad, anthraquinone is manufactured by a few large chemical companies (62). At present, only two processes for its production come into consideration manufacture by the Friedel-Crafts reaction utilizing benzene, phthahc anhydride, and anhydrous aluminum chloride, and by the vapor-phase catalytic oxidation of anthracene the latter method is preferred. 

Benzene is alkylated with propylene to yield cumene (qv). Cumene is catalytically oxidized in the presence of air to cumene hydroperoxide, which is decomposed into phenol and acetone (qv). Phenol is used to manufacture caprolactam (nylon) and phenoHc resins such as bisphenol A. Approximately 22% of benzene produced in 1988 was used to manufacture cumene. 

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. 

In a mixture of / -hexane and benzene (29), the deep catalytic oxidation rates of benzene and / -hexane in the binary mixture are lower than when these compounds are singly present. The kinetics of the individual compounds can be adequately represented by the Mars-VanKrevelen mechanism. This model needs refinements to predict the kinetics for the mixture. 

Some catalysts exposed to air stripping off-gas were subject to deactivation. However, using a catalytic oxidizer at a U.S. Coast Guard faciUty (Traverse City, Mich.) for the destmction of benzene, toluene, and xylene stripped from the groundwater, the catalytic oxidization unit operated at 260 to 315°C, and was able to achieve 90% destmction efficiency (see Groundwatermonitoring). 

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). 

Fumaric acid is used in the plastics industry, in the food industry and as a source of malic add. Although demand has increased rapidly over the last 30 years its production from fermentation has been totally replaced by a chemical method. It is now produced far more cheaply by the catalytic oxidation of hydrocarbons, particularly benzene. With the continuing uncertainties concerning the availability and cost of petroleum, however, fermentation may yet be a viable alternative. 

One of the exciting results to come out of heterogeneous catalysis research since the early 1980s is the discovery and development of catalysts that employ hydrogen peroxide to selectively oxidize organic compounds at low temperatures in the liquid phase. These catalysts are based on titanium, and the important discovery was a way to isolate titanium in framework locations of the inner cavities of zeolites (molecular sieves). Thus, mild oxidations may be run in water or water-soluble solvents. Practicing organic chemists now have a way to catalytically oxidize benzene to phenols alkanes to alcohols and ketones primary alcohols to aldehydes, acids, esters, and acetals secondary alcohols to ketones primary amines to oximes secondary amines to hydroxyl-amines and tertiary amines to amine oxides. 

Ethylene is obtained by catalytic cracking of naphtha. It is one of the key petrochemical commodities worldwide used mostly in the production of polyethylene, ethyl benzene, ethylene oxide and others. The consumption of ethylene for the production of alcohols and other surfactant raw materials represents less than 10% of the total end uses of ethylene on a worldwide basis. 

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... 

Acetyl-3-methyl-4,5-dihydrothiophen-4-one Benzyl alcohol, Hydrogen bromide, Iron Benzyl bromide, Molecular sieve Benzyl chloride, Catalytic impurities Benzyl fluoride l,2-Bis(chloromethyl)benzene Ethylene oxide, Contaminants Furoyl chloride... 

M. Iwamoto, K. Matsukami, and S. Kagawa, Catalytic oxidation by oxide radical ions. 1. One-step hydroxylation of benzene to phenol over group 5 or 6 oxides supported on silica gel, J. Phys. Chem. 87,903 (1983). 

It is important to emphasize that the atomic oxygen anion-radical plays a role in catalytic oxidation occnrring on varions oxide surfaces. For instance, O reacts with methane at room temperatnre over varions metal oxides (Lee and Gralowsky 1992). On solid catalysis, Q- is more reactive toward alkanes and alkenes than other ionic oxygen species. Iwamoto and Lnnsford (1980) assumed that O is the active oxygen species oxidizing benzene to phenol on with 70% selectivity at... 

Silica-supported iron materials catalyze oxidation reactions [152]. Fe(II) silsesqui-oxanes have been reported [153, 154]. On the complex based on the bisilanol 2a and diphenyl phosphinomethane, dppm [154], possible structural similarities with iron-zeolites where identified after loss of the diphosphane ligand by addition of water. The Fe-POSS were tested in the catalytic oxidation of benzene with N2O with little success [154]. 

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... 

Alkylation. Friedel-Crafts alkylation (qv) of benzene with ethylene or propylene to produce ethylbenzene [100-41 -4], CgH10, or isopropylbenzene [98-82-8], C9H12 (cumene) is readily accomplished in the liquid or vapor phase with various catalysts such as BF3 (22), aluminum chloride, or supported polyphosphoric acid. The oldest method of alkylation employs the liquid-phase reaction of benzene with anhydrous aluminum chloride and ethylene (23). Ethylbenzene is produced commercially almost entirely for styrene manufacture. Cumene [98-82-8] is catalytically oxidized to cumene hydroperoxide, which is used to manufacture phenol and acetone. Benzene is also alkylated with C1Q—C20 linear alkenes to produce linear alkyl aromatics. Sulfonation of these compounds produces linear alkane sulfonates (LAS) which are used as biodegradable deteigents. 

Schiff base-cobalt-nitro complexes are too mild as oxidants to react as such with alkenes. However, the addition of Lewis acids (e.g. BF3 Et20, LiPF6) to these complexes activates the nitro ligand and produces a variety of both stoichiometric and catalytic oxidations. Stoichiometric transformations involve the oxidation of sulfides to sulfoxides and 1,3-cyclohexadiene to benzene.467 Alcohols such as benzyl alcohol and cycloheptanol are catalytically transformed into the corresponding carbonyl compounds.467,474... 

Reactions (7.14)-(7.16) represent the main mechanistic steps not only of the stoichiometric, but also of the steady state catalytic oxidation of benzene to phenol. The involvement of a-oxygen in the catalytic oxidation is most convincingly evidenced by a linear dependence of the reaction rate on the concentration of a-sites [134,135]. 

More recently, sulfide oxidations with [hydroxy(tosyloxy)iodo]benzene (4, HTIB) have been reported [15]. Such reactions proceed readily in di-chloromethane at room temperature and stop at the sulfoxide stage (Scheme 2). HTIB can also be generated in situ from iodosylbenzene (5) and 10 mol% p-toluenesulfonic acid for catalytic oxidations of sulfides to sulfoxides [16]. Oxidations of unsymmetrical sulfides with the chiral (+)-10-camphorsulfonyloxy analog of HTIB afford the corresponding sulfoxides (82-92%) with low enan-tioselectivities (2.7-13.7% ee) [15]. 

The reactivity of the hydrocarbons increases in the order ortho < meta < para in the liquid-phase catalytic oxidation of methyl derivatives of biphenyl into acids by air. The mechanism of the oxidation of hydroxymethylbiphenyls and hydroxymethyl-benzenes involves the formation of an unstable cation radical, which is then stabilized by emitting a proton, giving hydroxybenzyl radical.243... 

Vassileva, M., A. Andreev, and S. Dancheva. 1991. Complete catalytic oxidation of benzene over supported vanadium oxides modified by silver. Appl. Catal. 69 221-234. 

Bielanski and Najbar63 observed on both fresh and reductively activated V205 and V205/Mo03 catalysts that the presence of (V=0) bonds is not essential for the selective oxidation of benzene to maleic anhydride. In a kinetic study of the catalytic oxidation of benzo (a) pyrene Young and... 

Jin L, Abraham MA. Low temperature catalytic oxidation of 1,4-dichloro-benzene. Ind Eng Chem Res 1991 30 89-95 Aki S, Abraham MA. Catalytic supercritical water oxidation of Pyridine comparison of catalysts. Ind Eng Chem Res 1999 38 358-367. 

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... 

The catalytic oxidation of benzene to maleic anhydride in a fluid bed reactor has been investigated by Kizer, Chavarie, Laguerie and Cassimatis (9). Their reactor had an inner diameter of 18 cm. Shallow beds of catalyst with bed heights less then 10 cm were used with reaction temperatures between 420 and 460 °C. The catalyst was silica supported VjOj. 

For split generation we make use of heuristics, as given in Table 3.1. The removal of troublesome impurities is suggested in the first place, here H2S, benzene and chloro-ethane. Then the split is placed in an appropriate selector, in this case of type purification . Table 3.3 indicates that six separation methods could be applied to perform this task chemical absorption, molecular-sieve adsorption, physical adsorption, catalytic oxidation, catalytic hydrogenation and chemical treatment. 

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