Phenol cumene manufacturing

Sales demand for acetophenone is largely satisfied through distikative by-product recovery from residues produced in the Hock process for phenol (qv) manufacture. Acetophenone is produced in the Hock process by decomposition of cumene hydroperoxide. A more selective synthesis of acetophenone, by cleavage of cumene hydroperoxide over a cupric catalyst, has been patented (341). Acetophenone can also be produced by oxidizing the methylphenylcarbinol intermediate which is formed in styrene (qv) production processes using ethylbenzene oxidation, such as the ARCO and Halcon process and older technologies (342,343). 

Phenol is manufactured from the hydrocarbon, cumene. Cumene (isopropylbenzene) is oxidised in the presence of air to cumene hydroperoxide. It is converted to phenol and acetone by treating it with dilute acid. Acetone, a by-product of this reaction, is also obtained in large quantities by this method. 

Acetone is the ketone used in largest quantity and is produced as a by-product of the manufacture of phenol via cumene. Manufacture from iso-propanol is by the reaction ... 

Cumene manufacture consumed about 10 percent (2.2 billion lb) of the propylene used for chemicals in the United States in 1998. It is prepared in near stoichiometric yield from propylene and benzene with acidic catalysts (scheme below). Many catalysts have been used commercially, but most cumene is made using a solid phosphoric acid catalyst. Recently, there has been a major industry shift to zeolite-based catalyst. The new process has better catalyst productivity and also eliminates the environmental waste from spent phosphoric acid catalyst. It significantly improves the product yield and lowers the production cost. Cumene is used almost exclusively as feed to the cumene oxidation process, which has phenol and acetone as its coproducts. 

For many years, phenol was manufactured b the Dow process, in which chlorobenzene reacts with NaOH at high temperature and pressure (Section 16.9). Now, however, an alternative synthesis from isopropylbenzene (cumene) is used. Cumene reacts with air at high temperature by a radical mechanism to form cumene hydroperoxide, which is converted into phenol and acetone by treatment with acid. This is a particularly efficient process because two valuable chemicals are prepared at the same time. 

Phenol. The manufacture of phenol by the oxidation of benzene is described by Denton (21) and by Simons and McArthur (107). The literature on phenol by the oxidation of cumene is partly covered in the reports of Frank (33), Hawkins (43), and Kharasch (57), mentioned earlier. A brief description and flow sheet of the process is given in Chemical Engineering (16). The patents in this field are mainly held by The Distillers Co., Ltd., Hercules Powder Co., and Allied Chemical and Dye Corp. In this phenol process large amounts of acetone are obtained as a coproduct. It should also be noted that the process may be directed to the production of cumene hydroperoxide and a,a dimethylbenzyl alcohol. Krieble (61) and Kenyon and Boehmer (55) describe the preparation of phenol by the chlorination and sulfonation processes. 

Benzene was first isolated by Faraday in 1825 from the liquid condensed by compressing oil gas. It is the lightest fraction obtained from the distillation of the coal-tar hydrocarbons, but most benzene is now manufactured from suitable petroleum fractions by dehydrogenation (54%) and dealkylation processes. Its principal industrial use is as a starting point for other chemicals, particularly ethylbenzene, cumene, cyclohexane, styrene (45%), phenol (20%), and Nylon (17%) precursors. U.S. production 1979 2-6 B gals. 

Propylation of benzene with propylene, catalyzed by supported phosphoric acid (or related catalysts such as AlCl ), gives cumene [98-82-8] in another important industrial process. Cumene (qv), through the intermediacy of cumene hydroperoxide, is used in the manufacture of phenol (qv). Resorcinol similarly can be made from y -diisopropylbenzene (6). 

Hydroperoxidation of m- or />Diisopropylbenzene. This is an important industrial route to resorcinol and hydroquinone. The process in principle is identical to the cumene process for the manufacturing of phenol (qv). 

The cumene oxidation route is the lea ding commercial process of synthetic phenol production, accounting for more than 95% of phenol produced in the world. The remainder of synthetic phenol is produced by the toluene oxidation route via benzoic acid. Other processes including benzene via cyclohexane, benzene sulfonation, benzene chlorination, and benzene oxychl orin ation have also been used in the manufacture of phenol. A Hst of U.S. phenol production plants and their estimated capacities in 1994 are shown in Table 2, and worldwide plants and capacities are shown in Table 3. 

Production of a-methylstyrene (AMS) from cumene by dehydrogenation was practiced commercially by Dow until 1977. It is now produced as a by-product in the production of phenol and acetone from cumene. Cumene is manufactured by alkylation of benzene with propylene. In the phenol—acetone process, cumene is oxidized in the Hquid phase thermally to cumene hydroperoxide. The hydroperoxide is spHt into phenol and acetone by a cleavage reaction catalyzed by sulfur dioxide. Up to 2% of the cumene is converted to a-methylstyrene. Phenol and acetone are large-volume chemicals and the supply of the by-product a-methylstyrene is weU in excess of its demand. Producers are forced to hydrogenate it back to cumene for recycle to the phenol—acetone plant. Estimated plant capacities of the U.S. producers of a-methylstyrene are Hsted in Table 13 (80). 

Benzoic Acid. Ben2oic acid is manufactured from toluene by oxidation in the liquid phase using air and a cobalt catalyst. Typical conditions are 308—790 kPa (30—100 psi) and 130—160°C. The cmde product is purified by distillation, crystallization, or both. Yields are generally >90 mol%, and product purity is generally >99%. Kalama Chemical Company, the largest producer, converts about half of its production to phenol, but most producers consider the most economic process for phenol to be peroxidation of cumene. Other uses of benzoic acid are for the manufacture of benzoyl chloride, of plasticizers such as butyl benzoate, and of sodium benzoate for use in preservatives. In Italy, Snia Viscosa uses benzoic acid as raw material for the production of caprolactam, and subsequendy nylon-6, by the sequence shown below. 

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. 

AH commercial processes for the manufacture of caprolactam ate based on either toluene or benzene, each of which occurs in refinery BTX-extract streams (see BTX processing). Alkylation of benzene with propylene yields cumene (qv), which is a source of phenol and acetone ca 10% of U.S. phenol is converted to caprolactam. Purified benzene can be hydrogenated over platinum catalyst to cyclohexane nearly aH of the latter is used in the manufacture of nylon-6 and nylon-6,6 chemical intermediates. A block diagram of the five main process routes to caprolactam from basic taw materials, eg, hydrogen (which is usuaHy prepared from natural gas) and sulfur, is given in Eigute 2. 

The acetone supply is strongly influenced by the production of phenol, and so the small difference between total demand and the acetone suppHed by the cumene oxidation process is made up from other sources. The largest use for acetone is in solvents although increasing amounts ate used to make bisphenol A [80-05-7] and methyl methacrylate [80-62-6]. a-Methylstyrene [98-83-9] is produced in controlled quantities from the cleavage of cumene hydroperoxide, or it can be made directly by the dehydrogenation of cumene. About 2% of the cumene produced in 1987 went to a-methylstyrene manufacture for use in poly (a-methylstyrene) and as an ingredient that imparts heat-resistant quaUties to polystyrene plastics. 

At one time the requirement for phenol (melting point 41°C), eould be met by distillation of eoal tar and subsequent treatment of the middle oil with eaustic soda to extraet the phenols. Such tar acid distillation products, sometimes containing up to 20% o-cresol, are still used in resin manufacture but the bulk of phenol available today is obtained synthetically from benzene or other chemicals by such processes as the sulphonation process, the Raschig process and the cumene process. Synthetic phenol is a purer product and thus has the advantage of giving rise to less variability in the condensation reactions. 

By far the preponderance of the 3400 kt of current worldwide phenolic resin production is in the form of phenol-formaldehyde (PF) reaction products. Phenol and formaldehyde are currently two of the most available monomers on earth. About 6000 kt of phenol and 10,000 kt of formaldehyde (100% basis) were produced in 1998 [55,56]. The organic raw materials for synthesis of phenol and formaldehyde are cumene (derived from benzene and propylene) and methanol, respectively. These materials are, in turn, obtained from petroleum and natural gas at relatively low cost ([57], pp. 10-26 [58], pp. 1-30). Cost is one of the most important advantages of phenolics in most applications. It is critical to the acceptance of phenolics for wood panel manufacture. With the exception of urea-formaldehyde resins, PF resins are the lowest cost thermosetting resins available. In addition to its synthesis from low cost monomers, phenolic resin costs are often further reduced by extension with fillers such as clays, chalk, rags, wood flours, nutshell flours, grain flours, starches, lignins, tannins, and various other low eost materials. Often these fillers and extenders improve the performance of the phenolic for a particular use while reducing cost. 

Delaney JL, Hughes TW. 1979. Source Assessment Manufacture of Acetone and Phenol from Cumene. Prepared by Monsanto Research Corp., Dayton, OH. EPA-600/2-79-019D. NTIS PB80-150592, 500. 

Most of the benzene used in chemical applications ends up in the manufacturing processes for styrene (covered in Chapter 8), cumene (covered in Chapter 7), and cyclohexane (covered in Chapter 4), Polymers and all sorts of plastics are produced from styrene. Cumene is the precursor to phenol, which ultimately ends up in resins and adhesives, mostly for gluing plywood together. The production of styrene and phenol account for. about 70% of the benzene produced. Cyclohexane, used to make Nylon 6 and Nylon 66, is the next biggest application of benzene. 

Ketones.have the characteristic -C- signature group imbedded in them. Acetone, CH3COCH3, comes from two different routes. It is a by-product in the cumene to phenol/acetone process. It is the on-purpose product of the catalytic dehydrogenation of isopropyl alcohol. Acetone is popular as a solvent and as a chemical intermediate for the manufacture of MIBK, methyl methacrylate, and Bisphenol A. 

The important derivatives of benzene are shown in Table 8.8. Ethylbenzene is made from ethylene and benzene and then dehydrogenated to styrene, which is polymerized for various plastics applications. Cumene is manufactured from propylene and benzene and then made into phenol and acetone. Cyclohexane, a starting material for some nylon, is made by hydrogenation of benzene. Nitration of benzene followed by reduction gives... 

As we learned in Chapter 8, the official production of propylene is usually about half that of ethylene, only because a large part of the propylene is used by petroleum refineries internally to alkylate gasolines. This captive use is not reported. Of the propylene used for chemical manufacture, nearly 40% is polymerized to polypropylene, to be discussed in a later chapter. Of the remaining amount of propylene, seven chemicals from the top 50 are manufactured. These are listed in Table 10.1. Their industrial manufacturing methods are summarized in Fig. 10.1. Note that four of these chemicals, cumene, phenol, acetone, and bisphenol A, are also derived from a second basic organic chemical, benzene. 

Cumene is an important intermediate in the manufacture of phenol and acetone. The feed materials are benzene and propylene. This is a Friedel-Crafts alkylation reaction catalyzed by solid phosphoric acid at 175-225 °C and 400-600 psi. The yield is 97% based on benzene and 92% on propylene. Excess benzene stops the reaction at the monoalkylated stage and prevents the polymerization of propylene. The benzene propylene ratio is 8-10 1. 

Presently there are two processes that make acetone in large quantities. The feedstock for these is either isopropyl alcohol or cumene. In the last few years there has been a steady trend away from isopropyl alcohol and toward cumene, but isopropyl alcohol should continue as a precursor since manufacture of acetone from only cumene would require a balancing of the market with the co-product phenol from this process. 

Bisphenol A is manufactured by a reaction between phenol and acetone, the two products from the cumene hydroperoxide rearrangement. The temperature of the reaction is maintained at 50 °C for about 8-12 hr. A sluny... 

There are nine chemicals in the top 50 that are manufactured from benzene. These are listed in Table 11.1. Two of these, ethylbenzene and styrene, have already been discussed in Chapter 9, Sections 5 and 6, since they are also derivatives of ethylene. Three others—cumene, acetone, and bisphenol A— were covered in Chapter 10, Sections 3-5, when propylene derivatives were studied. Although the three carbons of acetone do not formally come from benzene, its primary manufacturing method is from cumene, which is made by reaction of benzene and propylene. These compounds need not be discussed further at this point. That leaves phenol, cyclohexane, adipic acid, and nitrobenzene. Figure 11.1 summarizes the synthesis of important chemicals made from benzene. Caprolactam is the monomer for nylon 6 and is included because of it importance. 

The major manufacturing process for making phenol was discussed in Chapter 10, Section 4, since it is the co-product with acetone from the acid-catalyzed rearrangement of cumene hydroperoxide. The student should review this process. It accounts for 95% of the total phenol production and has dominated phenol chemistry since the early 1950s. But a few other syntheses deserve some mention. 

The related manufacture of cumene (isopropylbenzene) through the alkylation of benzene with propylene is a further industrially important process, since cumene is used in the synthesis of phenol and acetone. Alkylation with propylene occurs more readily (at lower temperature) with catalysts (but also with hydrogen fluoride and acidic resins) similar to those used with ethylene, as well as with weaker acids, such as supported phosphoric acid (see further discussion in Section 5.5.3). 

Chlorobenzene. Chlorobenzene is an important solvent and intermediate in the production of chemicals and dyes. Its use in phenol manufacture, however, was superseded by the introduction of the cumene process. 

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. 

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