Cumene-phenol process

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... 

Sunoco/UOP LLC, A Honeywell Co. Phenol Cumene Process produces high-quality phenol and acetone by liquid-phase peroxidation of cumene 14 NA... 

Most of the world s acetone is now obtained as a coproduct of phenol by the cumene process, which is used by 21 of 31 producing companies in North America, Western Europe, and Japan. Cumene is oxidi2ed to the hydroperoxide and cleaved to acetone and phenol. The yield of acetone is beheved to average about 94%, and about 0.60—0.62 unit weight of acetone is obtained per unit of phenol (13). 

Synthetic phenol capacity in the United States was reported to be ca 1.6 x 10 t/yr in 1989 (206), almost completely based on the cumene process (see Cumene Phenol). Some synthetic phenol [108-95-2] is made from toluene by a process developed by The Dow Chemical Company (2,299—301). Toluene [108-88-3] is oxidized to benzoic acid in a conventional LPO process. Liquid-phase oxidative decarboxylation with a copper-containing catalyst gives phenol in high yield (2,299—304). The phenoHc hydroxyl group is located ortho to the position previously occupied by the carboxyl group of benzoic acid (2,299,301,305). This provides a means to produce meta-substituted phenols otherwise difficult to make (2,306). VPOs for the oxidative decarboxylation of benzoic acid have also been reported (2,307—309). Although the mechanism appears to be similar to the LPO scheme (309), the VPO reaction is reported not to work for toluic acids (310). 

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). 

Cumene Process. There are several Hcensed processes to produce phenol which are based on cumene (qv) (1,8—11). AH of these processes consist of two fundamental chemical reactions cumene is oxidized with air to form cumene hydroperoxide, and cumene hydroperoxide is cleaved to yield phenol and acetone. In this process, approximately 0.46 kg of acetone and 0.75 kg of phenol are produced per kg of cumene feedstock. 

The recovery area of the plant employs fractionation to recover and purify the phenol and acetone products. Also in this section the alpha-methylstyrene is recovered and may be hydrogenated back to cumene or recovered as AMS product. The hydrogenated AMS is recycled as feedstock to the reaction area. The overall yield for the cumene process is 96 mol %. Figure 1 is a simplified process diagram. 

Table 4 shows the worldwide and U.S. production figures and prices for phenol since the mid-1980s. Because the cumene process accounts for more than 95% of the world s phenol supply, the economics of phenol production are closely tied to this production method. In the cumene process 615 kg of acetone are coproduced with each ton of phenol produced. Thus, the economics of phenol production are influenced by acetone (qv). 

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. 

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). 

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. 

Cumene processes are currently the major source for phenol and coproduct acetone. Chapter 8 notes other routes for producing acetone. 

The most common precursor to phenolic resins is phenol. More than 95% of phenol is produced via the cumene process developed by Hock and Lang (Fig. 7.1). Cumene is obtained from the reaction of propylene and benzene through acid-catalyzed alkylation. Oxidation of cumene in air gives rise to cumene hydroperoxide, which decomposes rapidly at elevated temperatures under acidic conditions to form phenol and acetone. A small amount of phenol is also derived from coal. 

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. 

Phenol is the major source of Bakelite and phenol resins, which are utihzed in many commodities worldwide phenol is also used as reagent for syntheses of dyes, medicines and so on. The industrial demand for phenol has increased every year and its production now exceeds 7.2 megaton year 94% of the worldwide production of phenol is processed in the cumene process. The cumene process involves the reaction of benzene with propene on acid catalysts like MCM-22, followed by auto-oxidation of the obtained cumene to form explosive cumene hydroperoxide and, finally, decomposition of the cumene hydroperoxide to phenol and acetone in sulfuric acid (Scheme 10.3) [73],... 

The three-step cumene process, including the liquid-phase reactions and using sulfuric acid, is energy-consuming, environmentally unfavorable and disadvantageous for practical operation the process also produces as an unnecessary byproduct acetone, stoichiometrically. Furthermore, the intermediate, cumene hydroperoxide, is explosive and cannot be concentrated in the final step, resulting in a low one-path phenol yield, ( 5%, based on the amount of benzene initially used). Thus, direct phenol synthesis from benzene in one-step reaction with high... 

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. 

In conclusion no catalysts with good performances (>5% conversion and >50% selectivity, simultaneously) have been discovered to date. New selective catalysts for direct phenol synthesis from benzene with 02 are essential for the novel industrial process replacing the cumene process - there are many problems to be resolved. 

Phenol is an important chemical intermediate of industrial interest, used as substrate for the production of antioxidants, polymers and agrochemicals. Actually, more than of 90% of the world production is realized by the three-step cumene process that leads to the formation of acetone as by-product. 

In the cumene process (Fig. 1), cumene is oxidized to form cumene hydroperoxide that is then concentrated and cleaved to produce phenol and acetone. By-products of the oxidation reaction are acetophenone and dimethyl benzyl alcohol, which is dehydrated in the cleavage reaction to produce alpha-methylstyrene. 

Inserting oxygen into the C-H bond of an alkane initially leads to hydroperoxides. When this reaction is performed with atmospheric oxygen it is also called autooxidation. It usually leads to a multitude of products, because of further spontaneous reactions, so this reaction is of limited synthetic use. An exception is oxidation of isobutane with oxygen, which leads to 70 % yield of tert-butyl hydroperoxide at a conversion of 80% (Table 1, entry 7). Hydrogen bromide is used, among other compounds, as an initiator [15]. tert-Butyl hydroperoxide is used as an oxidant in propylene oxide production by the Halcon process. In the formation of phenol by the cumene process cumene is oxidized into the corresponding hydroperoxide in a similar way. 

Although cyclohexane oxidation dominates the market, because of cheaper raw materials, the hydrogenation of phenol remains competitive, offering better selectivity with fewer environmental and safety problems. In addition, this process allows efficient valorization of phenol-rich wastes from coal industries. Recently built plants make use of this technology, as reported by the engineering group Aker-Kvaerner (www.kvaerner.com, 2004). The availability of low-price phenol is the most important element for profitability. Besides the well-known cumene process, a promising route is the selective oxidation of benzene with N20 on iron-modified ZSM-5 catalyst [12]. In this way, the price of phenol may become independent of the market of acetone. 

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

The world production of phenol, of ca. 8.4 Mt/a, is mostly dependent on the cumene process. The yields and selectivities of the process are almost quantitative. However, the per-pass yield is relatively low (< 8.5%) and ca. 0.6 tonne of acetone is co-produced per 1 tonne of phenol. The hydrogenation-dehydration of acetone and its recycle has been considered but is not practised commercially. 

TS-1 is a good catalyst for the hydroxylation of benzene when it is used in a highly polar medium, such as sulfolane. This promotes the fast desorption of the product thus hindering its further oxidation (Annex 2). The selectivity of 94% to phenol (plus 6% hydroquinone and catechol), obtained at 9% benzene conversion, is comparable to the per-pass yield of the cumene process. 

Most important is the cumene process with an 80-85% share worldwide cumene (isopropylbenzene obtained from alkylation of benzene with propylene) is oxidized to the corresponding hydroperoxide which is decomposed to a mixture of phenol and acetone. In Japan the second most important process for acetone production is the direct oxidation of propylene with a 12% share. 

The pretreatment of TS-1 with a solution of ammonium fluoride and hydrogen peroxide further increased the conversion (ca 9%) and selectivity. The recovery of catechol and hydroquinone, by their hydrogenahon back to phenol, was also considered [55]. It is worth noting that, at a threshold yield value of ca 9%, the hydroxylation of benzene could become compehhve with the cumene process, considering that the overall per pass yield in the latter does not exceed 8-9%. 

Dihydroxybenzene may be prepared from 2-hydroxybenzaldehyde by the Dakin reaction, which involves oxidation in alkaline solution by hydrogen peroxide (Scheme 4.15). The reaction involves a 1,2-shift to an electron-deficient oxygen and is similar to the cumene process used to synthesize phenol (Section 4.2). 

In a new process for making phenol, cumene (isopropylbenzene) is oxidized with air to form cumene hydroperoxide, which is then changed to phenol and acetone. The cumene is made by the direct alkylation of gaseous benzene, using a phosphoric acid-kieselguhr catalyst and operating conditions of 500 K. 

Derivation (1) By fractional distillation of crude cresol (2) from benzene by the cumene process (see phenol). 

Improved yields under less drastic conditions and the decreased waste stream problems of the cumene process to phenol have led to the phasing out of these older processes. 

Among these processes, only the Hock process and the toluene oxidation are important industrially. The other processes were discarded for economic reasons. In the Hock process acetone is formed as a by-product. This has not, however, hindered the expansion of this process, because there is a market for acetone. New plants predominantly use the cumene process. More than 95% of the 4,691,000 my (m = metric tonnes) consumed is produced by the cumene peroxidation process. Phenol s consumption growth rate of 3% is primarily based on its use in engineering plastics such as polycarbonates, polyetherimide and poly(phenylene oxide), and epoxy resins for the electronic industry. The Mitsui Company is, for instance, the world s second largest producer of phenol. Japan s production... 

Determination of phenol by C NMR spectroscopy has the advantage that each determination affords three independent results that can be averaged, allowing rejection of results with too large RSD. The method was applied to the determination of phenol in tars of the cumene process, and were correlated with those of H NMR, UVV spectroscopy and titration with bromine. RSD for single results was 0.8% . ... 

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