Cumene acetone from

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). 

Chemicals Based on Benzene, Toluene, and Xylenes 271 Phenol and Acetone from Cumene... 

Figure 10-6. The Mitsui Petrochemical Industries process for producing phenol and acetone from cumene (1) autooxidatlon reactor, (2) vacuum tower, (3) cleavage reactor, (4) neutralizer, (5-11 ) purification train.

Autoxidation. Self-catalyzed oxidation in the presence of air. Autoxidation can be initiated by heat, light, or a catalyst. The commercial production of phenol and acetone from cumene is autoxidation. Other examples include the degradation of polymers exposed to sunlight for long periods of time gum formation in lubricating oils and gasoline and the spoilage of fats. 

Liquid phase oxidation of hydrocarbons by molecular oxygen forms the basis for a wide variety of petrochemical processes,3 "16 including the manufacture of phenol and acetone from cumene, adipic acid from cyclohexane, terephthalic acid from p-xylene, acetaldehyde and vinyl acetate from ethylene, propylene oxide from propylene, and many others. The majority of these processes employ catalysis by transition metal complexes to attain maximum selectivity and efficiency. 

Application Improved technology to produce highest quality phenol and acetone from cumene. Refined alpha methyl styrene (AMS) production is optional. High yield is achieved at low operating and capital costs without tar cracking. 

Application A high-yield process to produce high-purity phenol and acetone from cumene with optional byproduct recovery of alpha methylstyrene (AMS) and acetophenone (AP). 

FIGURE 7.23 The production of phenol and acetone from cumene Is a two-step process that involves insertion of O2 to make a peroxide, followed by acid-catalyzed migration of the —OH group to form the products. 

Molecular oxygen can also oxidize a variety of organic compounds, including hydrocarbons, aldehydes, amines, ethers and ketones. These autooxidation reactions can be used to make a variety of small molecules and a number of industrial processes rely on the controlled oxidation of organics using molecular oxygen (often with a metal catalyst). Examples include the formation of phenol and acetone from cumene (isopropylbenzene) and cyclohexanone from cyclohexane. Phenol is a popular starting material for a number... 

Distillation bottom tars from the production of phenol/acetone from cumene (T)... 

Hock process A process used to produce phenol and acetone from cumene (isopropyl benzene). The process first involves using air in the oxidation of cumene liquid to form cumene hydroperoxide ... 

It was realized during World War 11 that alkylated benzene molecules coirld be used to increase the octane level of aviation gasoline. The Petroleum Administration for War had asked for a high-octane synthetic aromatic component in 1941 and propyl benzene, also known as cumene, and butyl benzene were produced in the United States and the United Kingdom, respectively. In 1944, the Hock and Lang process," which produced phenol and acetone from cumene was introduced, and this industrial process became the basis of the major source of phenol throughout the world ... 

From cumene Almost all the phenol produced in the United States is prepared by this method Oxi dation of cumene takes place at the benzylic posi tion to give a hydroperoxide On treatment with dilute sulfuric acid this hydroperoxide is converted to phenol and acetone... 

Dehydrogenation of isopropyl alcohol accounts for most of the acetone production not obtained from cumene. The vapor is passed over a brass, copper, or other catalyst at 400—500°C, and a yield of about 95% is achieved (1.09 unit weight of alcohol per unit of acetone) (13). 

Almost 95% of the acetone produced in the United States in 1987 and 1988 was made from cumene and 4% from isopropyl alcohol (13). 

The yield of acetone from the cumene/phenol process is beUeved to average 94%. By-products include significant amounts of a-methylstyrene [98-83-9] and acetophenone [98-86-2] as well as small amounts of hydroxyacetone [116-09-6] and mesityl oxide [141-79-7]. By-product yields vary with the producer. The a-methylstyrene may be hydrogenated to cumene for recycle or recovered for monomer use. Yields of phenol and acetone decline by 3.5—5.5% when the a-methylstyrene is not recycled (21). 

The economics of acetone production and its consequent market position are unusual. Traditional laws of supply and demand cannot be appHed because supply depends on the production of phenol and demand is controUed by the uses of acetone. Therefore, coproduct acetone from the cumene to phenol process will continue to dominate market supply. DeHberate production of acetone from isopropyl alcohol accommodates demand in excess of that suppHed by the phenol process. More than 75% of world and 90% of U.S. production comes from the cumene to phenol process. 

The cumene is oxidized to cymene hydroperoxide, which decomposes to cresols and acetone. The process is similar to phenol (qv) production from cumene. 

After an initial distillation to split the coproducts phenol and acetone, each is purified in separate distillation and treating trains. An acetone finishing column distills product acetone from an acetone/water/oil mixture. The oil, which is mostly unreacted cumene, is sent to cumene recovery. Acidic impurities, such as acetic acid and phenol, are neutralized hy caustic injection. Figure 10-7 is a simplified flow diagram of an acetone finishing column, and Table 10-1 shows the feed composition to the acetone finishing column. 

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. 

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. 

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. 

There is a compelling reason to integrate PMMA and phenol-formaldehyde because the monomers phenol and acetone are both made from cumene oxidation (previous chapter). Therefore, one makes one mole of phenol for every mole of acetone, and a producer would have to sell one of these monomers if he did not have an integrated process to produce both polymers or some other products. 

Major markets as solvents and intermediates have made the ketones important commercial products lor many years. Acetone and mcthylethyl ketone have had the most impact on the chemical industry Acetone Is used s an intermediate In methyl isobutyl ketone, methyl methacrylate, diucelonc alcohol. ketone. hisphenol-A. phiwnc. and mesityl oxide Acetone is largely produced by dehydration of isopropyl alcohol In the production of phenol from cumene, acetone is produced as a by-product This mute to acetone has tended to control its price. 

Acetone. Acetone in commerce is derived mostly from cumene oxidation. This is a two-step process involving oxidation of cumene to... 

Cumene capacity topped 9.5 million metric tons in 1998 and is projected to reach 10.4 million metric tons by the end of 2003 (19). Like ethylbenzene, cumene is used almost exclusively as a chemical intermediate. Its primary use is in the coproduction of phenol and acetone through cumene peroxidation. Phenolic resins and bisphenol A are the main end uses for phenol. Bisphenol A, which is produced from phenol and acetone, has been the main driver behind increased phenol demand. Its end use applications are in polycarbonate and epoxy resins. The growth rate of cumene is closely related to that of phenol and is expected to be approximately 5.1% per year worldwide over the next five years. Process technologies for both chemicals have been moving away from conventional aluminum chloride and phosphoric acid catalyzed Friedel-Crafts alkylation of benzene, toward zeolite-based processes. 

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