Phenol cumene oxidation process

Gumylphenol. -Cumylphenol (PGP) or 4-(1-methyl-l-phenylethyl)phenol is produced by the alkylation of phenol with a-methylstyrene under acid catalysis. a-Methylstyrene is a by-product from the production of phenol via the cumene oxidation process. The principal by-products from the production of 4-cumylphenol result from the dimerization and intramolecular alkylation of a-methylstyrene to yield substituted indanes. 4-Cumylphenol [599-64-4] is purified by either fractional distillation or crystallization from a suitable solvent. Purification by crystallization results in the easy separation of the substituted indanes from the product and yields a soHd material which is packaged in plastic or paper bags (20 kg net weight). Purification of 4-cumylphenol by fractional distillation yields a product which is almost totally free of any dicumylphenol. The molten product resulting from purification by distillation can be flaked to yield a soHd form however, the soHd form of 4-cumylphenol sinters severely over time. PGP is best stored and transported as a molten material. 

More than 95% of the cumene produced is used as feedstock for the production of phenol (qv) and its coproduct acetone (qv). The cumene oxidation process for phenol synthesis has been growing in popularity since the 1960s and is prominent today. The first step of this process is the formation of cumene hydroperoxide [80-15-9]. The hydroperoxide is then selectively cleaved to phenol [108-95-2] and acetone [67-64-1/ in an acidic environment (21). 

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. 

Phenol is the starting material for numerous intermediates and finished products. About 90% of the worldwide production of phenol is by Hock process (cumene oxidation process) and the rest by toluene oxidation process. Both the commercial processes for phenol production are multi step processes and thereby inherently unclean [1]. Therefore, there is need for a cleaner production method for phenol, which is economically and environmentally viable. There is great interest amongst researchers to develop a new method for the synthesis of phenol in a one step process [2]. Activated carbon materials, which have large surface areas, have been used as adsorbents, catalysts and catalyst supports [3,4], Activated carbons also have favorable hydrophobicity/ hydrophilicity, which make them suitable for the benzene hydroxylation. Transition metals have been widely used as catalytically active materials for the oxidation/hydroxylation of various aromatic compounds. 

Fermentation and distillation techniques for acetone production were replaced starting in the 1950s with the cumene oxidation process (Figure 2.1). In this process, cumene is oxidized to cumene hydroperoxide, which is then decomposed using acid to acetone and phenol. This is the primary method used to produce phenol, and acetone is produced as a co-product in the process, with a yield of about 0.6 1 of acetone to phenol. 

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. 

ABB Lummus Global Phenol Cumene Cumene oxidation process with advanced cleavage technology for improved yield 2 1995... 

Lummus Technology Phenol Cumene Cumene oxidation process with ability to produce alphamethylstyrene and pharmaceutical-grade acetone byproducts 2 2008... 

Phenol and acetone are produced from benzene and propene by the cumene route, which can be divided into cumene process and cumene oxidation process [1]. Benzene and propene react to cumene in the cumene process. In the cumene oxidation process, cumene is oxidized to cumene hydroperoxide (CHP), which is converted into phenol and acetone in a successive reaction, the so-called cleavage. The oxidation of cumene to CHP is described in detail in the following sections. 

The cleavage of CHP into phenol and acetone was first reported by Hock and Lang [2]. Hence, the cumene oxidation process for the production of phenol and acetone is known as the Hock process. As claimed by Zakoshansky [3], the reaction route was supposedly discovered in parallel in the former USSR. 

Minor amounts of CHP are used as an initiator in polymerization processes. However, the dominant use of CHP is as an intermediate product in the cumene oxidation process. Based on the worldwide phenol production capacity (in 2013) of approximately 11.4x 10 t, the production capacity of CHP can be estimated to be 18.8xl0 t/a. 

In the cumene oxidation process, in a first reaction cumene is oxidized to CHP. In a second reaction, CHP is cleaved to phenol and acetone by using a strong mineral acid as catalyst. The reaction heat is 117kJ/mol for the oxidation and 252 kJ/mol for the cleavage. The oxidation is carried out at pressures ranging from atmospheric to approximately 7 bar and temperatures between 80 and 120 C. The cleavage is performed around atmospheric pressure and temperatures in the range between 40 and 80 °C. 

In the beginning of the cumene oxidation process, oxidation was carried out as a three-phase reaction [25—27], the so-called wet oxidation. In addition to cumene and air, an aqueous sodium carbonate solution was continuously added to the reactors to extract and neutralize organic acids that are formed during oxidation. Phenolchemie, now INEOS Phenol, was the first to operate reactors without adding any caustic soda or sodium carbonate [28], which is called dry oxidation. Such a process is easier to handle and even leads to higher yields. 

In the recent past, the focus of new developments was on alternative phenol processes that overcome the disadvantage of the coupled product acetone in the cumene oxidation process. These processes are based on the oxidation of benzene with nitrous oxide or hydrogen peroxide [7]. The main research on the cumene oxidation process is process intensification by improving the oxidation reaction and improved process and reactor design. 

The oxidation reaction is a radical chain reaction, which can be influenced by radical scavengers, such as phenol. As phenol is produced from GHP, the risk of phenol recycling within the cumene oxidation process is always present. To reduce the... 

Probably the most intensively studied derivative of styrene with regard to its polymerization behavior is a-methylstyrene. It is produced commercially by the dehydrogenation of isopropyl-benzene (cumene) and also as a by-product in the production of phenol and acetone by the cumene oxidation process. The polymerization characteristics of ot-methylstyrene are considerably dilferent from those of styrene. Whereas radical polymerization of the pure monomer proceeds very slowly and is therefore not a practical technique [196], both ionic and coordination-type polymerization can be used to prepare poly(a-methylstyrene) (PMS). 

Isopropyl alcohol (IPA) has been called the first petrochemical. Both historically and today, it is prepared by sulfuric acid-mediated indirect hydration of propylene (see equations below and Fig. 22.28). Originally it was the source of most of the acetone used in the world. Now, this route must compete with acetone derived from the cumene oxidation process, in which cumene is converted to equimolar amounts of phenol and acetone. Between 1959 and 1978 the amount of acetone derived from IPA dehydrogenation declined from 80 percent to 34 percent, and the amount of IPA used for this purpose declined from 47 percent in 1978 to 12 percent in 1990. 

Cumene Hydroperoxide Process for Phenol and Acetone. Ben2ene is alkylated to cumene, which is oxidized to cumene hydroperoxide, which ia turn is cleaved to phenol and acetone. 

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. 

A typical phenol plant based on the cumene hydroperoxide process can be divided into two principal areas. In the reaction area, cumene, formed by alkylation of benzene and propylene, is oxidized to form cumene hydroperoxide (CHP). The cumene hydroperoxide is concentrated and cleaved to produce phenol and acetone. By-products of the oxidation reaction are acetophenone and dimethyl benzyl alcohol (DMBA). DMBA is dehydrated in the cleavage reaction to produce alpha-methylstyrene (AMS). 

The most widely used process for the production of phenol is the cumene process developed and Hcensed in the United States by AHiedSignal (formerly AHied Chemical Corp.). Benzene is alkylated with propylene to produce cumene (isopropylbenzene), which is oxidized by air over a catalyst to produce cumene hydroperoxide (CHP). With acid catalysis, CHP undergoes controUed decomposition to produce phenol and acetone a-methylstyrene and acetophenone are the by-products (12) (see Cumene Phenol). Other commercial processes for making phenol include the Raschig process, using chlorobenzene as the starting material, and the toluene process, via a benzoic acid intermediate. In the United States, 35-40% of the phenol produced is used for phenoHc resins. 

Oxidation of organic compounds by dioxygen is a phenomenon of exceptional importance in nature, technology, and life. The liquid-phase oxidation of hydrocarbons forms the basis of several efficient technological synthetic processes such as the production of phenol via cumene oxidation, cyclohexanone from cyclohexane, styrene oxide from ethylbenzene, etc. The intensive development of oxidative petrochemical processes was observed in 1950-1970. Free radicals participate in the oxidation of organic compounds. Oxidation occurs very often as a chain reaction. Hydroperoxides are formed as intermediates and accelerate oxidation. The chemistry of the liquid-phase oxidation of organic compounds is closely interwoven with free radical chemistry, chemistry of peroxides, kinetics of chain reactions, and polymer chemistry. 

The effect of jumping of the maximal hydroperoxide concentration after the introduction of hydrogen peroxide is caused by the following processes. The cumyl hydroperoxide formed during the cumene oxidation is hydrolyzed slowly to produce phenol. The concentration of phenol increases in time and phenol retards the oxidation. The concentration of hydroperoxide achieves its maximum when the rate of cumene oxidation inhibited by phenol becomes equal to the rate of hydroperoxide decomposition. The lower the rate of oxidation the higher the phenol concentration. Hydrogen peroxide efficiently oxidizes phenol, which was shown in special experiments [8]. Therefore, the introduction of hydrogen peroxide accelerates cumene oxidation and increases the yield of hydroperoxide. 

Cumox [Cumene oxidation] A process for making acetone and phenol by oxidizing cumene, based on the Hock process. This version was further developed and licensed by UOR Three plants were operating in 1986. UOP now licenses the Allied-UOP Phenol process, which combines the best features of Cumox and a related process developed by the Allied Chemical Corporation. 

Hock Also known as the Hock Lang process, and the cumene peroxidation process. A process for converting isopropyl benzene (cumene) to a mixture of phenol and acetone m-di-isopropyl benzene likewise yields resorcinol, and p-di-isopropyl benzene yields hydro-quinone. The basis of the process is the liquid-phase air oxidation of cumene to cumene hydroperoxide ... 

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. 

A substantial amount of a-methylstyrene is produced during the cumene oxidation step in the production of phenol and acetone. Slurry processes applying Raney nickel and a fixed-bed operation with palladium developed by Engelhard326,341 are used to hydrogenate and recycle a-methylstyrene to produce more phenol and acetone. 

The thermal decompn of Cumene Hydroperoxide has been studied by several authors (cited in Refs 6 8). Realization of the potential industrial importance of this compd and its acid-catalyzed conversion to phenol acetone, caused the appearance of many papers many patents involving the efficiency of both the oxidation process and the decompn stage (Ref 3)... 

As examples of oxidation processes, two processes are available for the manufacture of phenol, and both involve oxidation. The major process involves oxidation of cumene to cumene hydroperoxide, followed by decomposition to phenol and acetone. A small amount of phenol is also made by the oxidation of toluene to benzoic acid, followed by decomposition of the benzoic acid to phenol. 

Before 1970, there were five different processes used to make phenol in the United States the sulfonation route, chlorobenzene hydrolysis, the Raschig process, cumene oxidation, and the benzoic acid route. By 1978, the first three processes had essentially disappeared, and 98 percent of the remaining plant capacity was based on cumene oxidation. The oxidation process is shown in Fig. 10.33. 

Fig. 10.33. Manufacture of phenol and acetone by oxidation of cumene. (Hydrocarbon Processing, p. 117, 2001, March. Copyright 2001 by Gulf Publishing Co.)...

Production of monochlorobenzenes peaked in the 1960s with production volume at about 600 million lb. It was down to 152 million lb in 1998. The most significant cause for the decline is the replacement of monochlorobenzene by cumene as the preferred raw material for phenol manufacture. Other reasons include the elimination of the herbicide DDT, the change of diphenyl oxide process from chlorobenzene to phenol and a significant drop in solvent use. The production volume for ODCB and PDCB were 50 and 91 million lb, respectively, in 1998. 

UOP/Sunoco Phenol Cumene Process characteristics low-pressure oxidation for 1.31 tons of cumene/ton of phenol high-purity phenol (polycarbonate BPA grade) 11 1996... 

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