SK14332000A3 - Process for the preparation of phenol, acetone and methylethylketone - Google Patents

Abstract

A mixture containing cumene (I) and sec.-butylbenzene (II) with a sec.-butylbenzene content of up to 25 wt% is used in a process for the production of phenol, methyl ethyl ketone (MEK) and acetone by oxidation of this mixture with gas containing molecular oxygen, followed by Hock cleavage of the resulting hydroperoxides of (I) and (II).

Description

Technical field

The invention relates to a process for the production of phenol, acetone and methyl ethyl ketone by oxidation of a mixture comprising cumene and sec-butylbenzene and subsequent Hock cleavage of cumene hydroperoxide and sec-butylbenzene hydroperoxide.

BACKGROUND OF THE INVENTION

Phenol is an important chemical base material with a wide range of uses. In addition to being used as a solvent, it is used, inter alia, for the production of phenol-formaldehyde resins, 4,4'-dihydroxydiphenyl-2,2-propane (dian), ε-caprolactam, adipic acid, alkylphenols and plasticizers.

The production of phenol by Hock cleavage of a suitable hydroperoxide is known. In addition to phenol as the hydroxy compound, a carbonyl compound is still produced as an associated product, which, for economic reasons, also has to be brought to a suitable recovery.

EP-0 548 986 A1 discloses a process for producing phenol and methyl ethyl ketone (abbreviated as MEK) as an associated product by oxidation of sec-butylbenzene to sec-butylbenzene hydroperoxide and Hock cleavage of sec-butylbenzene hydroperoxide to phenol and MEK. In addition to acetone, MEK is one of the most technically important ketones used primarily as a solvent for lacquers and resins. In EP-0 548 986 A1 it is proposed that the process be carried out in accordance with the invention. The use of sec-butylbenzene as a starting material which is essentially free of either ethyl hydroperoxide, carboxylic acids and phenol, or substantially free of styrene compounds, or substantially free of methylbenzyl alcohol. In particular, by means of suitable embodiments of the process directed towards these batch materials, the additional separation of the unwanted by-products is achieved by special additional processing steps. Thereby unreacted sec-butylbenzene can be recycled to the oxidation step without adversely affecting the rate of oxidation.

AP-0 578 194 A2 also discloses a process for producing phenol and MEK from sec-butylbenzene. Described is a process which, in connection with the usual process steps by oxidation, concentration and cleavage, exhibits special processing steps, in particular washing of the MEK fraction separated by distillation, with alkali, thereby overall obtaining MEK of higher purity.

U.S. Pat. No. 4,532,360 discloses a direct, one-step process that can be used to produce phenol and MEK from sec-butylbenzene. The oxidation of the sec-butylbenzene is carried out in the presence of hydrogen bromide or hydrogen chloride as well as at least one additive selected from cerium oxide, triphenylborate, boron triphosphate and water, whereby the direct cleavage of the sec-butylbenzene hydroperoxide into phenol and MEK.

JP-62-114 922 of May 26, 1987 discloses a process for the simultaneous production of phenol, MEK and acetone by oxidation of sec-butylbenzene with a molecular oxygen-containing gas in the presence of cumene and cumene hydroperoxide. Addition of 5 to 60 wt. % of cumene hydroperoxide concentrate containing 65 to 85 wt. cumene hydroperoxide, for seconds, · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · % By weight of tylbenzene, or by addition of at least 50 wt.%, Preferably 30 to 70 wt. % cumene to sec-butylbenzene; refers to the content of sec-butylbenzene, an increased reaction rate is achieved in the oxidation of sec-butylbenzene. Furthermore, the dependence of the rate of oxidation of sec-butylbenzene on the isobutylbenzene content and the formation of acetophenone by-product are reduced. Thus, when cumene is added to sec-butylbenzene, oxidation is performed with a reduced amount of cumene.

However, phenol is currently produced mainly by Hock cleavage of cumene hydroperoxide, whereby acetone is formed as an associated product. Acetone also has a wide range of uses, for example as a solvent or for the preparation of, inter alia, 4,4'-dihydroxydiphenyl-2,2-propane and methyl methacrylate.

In this so-called cumene process for the production of phenol and acetone, the cumene is first oxidized, preferably by air or oxygen, to cumene hydroperoxide, which is usually after distillation by separating unreacted cumene to a cumene hydroperoxide content of 60 to 85% by weight. it then cleaves under acid catalysis, preferably with sulfuric acid, into phenol and acetone. A good overview of the cumene method is provided, for example, by Weissermel / Arpe, Industrielle Organische Chemie, 2nd edition, Verlag Chemie, 1978 or Ullmann's Encyclopedia of Undustrial Chemistry, Vol. A 19, p. 302 et al., VCH Verlagsgesellschaft, 1991. Recent further developments of the cumene process relate primarily to the field of cumene hydroperoxide cleavage and the processing of the cleavage product to reduce by-product formation and energy consumption, cf. for example EP-0 589 588 A1, EP-0 670 296 A1 or WO 97/06905.

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The cumene production process still results in equal proportions in the recovery of phenol and acetone. With respect to weight, 0.62 tons of acetone is produced per tonne of phenol. An essential purpose of the use of both products is the synthesis of 4,4'-dihydroxydiphenyl-2,2-propane, whereby according to the reaction equation starting from 2 moles of phenol and 1 mole of acetone, 1 mole of 4,4'-dihydroxydiphenyl-2,2-propane is obtained. 4,4'-Dihydroxydiphenyl 2,2-propane serves as a starting material for the production of polycarbonates and epoxy resins and is therefore produced in large quantities. However, for the synthesis of 4,4 ' -dihydroxydiphenyl-2,2-propane, only half of acetone is needed relative to the mole, relative to the mole. While there are other uses for acetone, for example as a solvent or for the production of, for example, methyl methacrylate, overall market growth is predicted for phenol and acetone so that a little more phenol than acetone will be required, based on moles. However, the cumene process used mainly for the production of phenol and acetone could not respond to this different market requirement on the basis of its reaction scheme.

Accordingly, it is an object of the present invention to provide a phenol production process which, although acetone is also produced but does not necessarily produce an equimolar amount of phenol and acetone as a cumene process, but allows a flexible adaptation of production likely to slightly higher phenol demand than acetone relative to moles.

SUMMARY OF THE INVENTION

According to the invention, this object is achieved by a process for the production of phenol, acetone and methyl ethyl ketone by oxidizing a mixture comprising cumene and sec-butylbenzene with a molecular oxygen-containing gas followed by Hock cleavage of cumene hydroperoxide and sec-butylbenzene hydroperoxide. -butylbenzene contains up to 25 wt. sec-butyl benzene.

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Preferably, this mixture consists only of cumene and sec-butylbenzene.

Surprisingly, it has been found that by means of the process steps known from the cumene process, mixtures containing simultaneously cumene and small amounts of up to 25% by weight can also be processed. sec-butylbenzene and together can be converted to phenol, acetone and cyclohexanone. As a result, the mole ratio of phenol, acetone and MEK can be controlled in a targeted manner by adjusting the composition of the starting material mixture in the product mixture and, as a rule, avoiding a commercially unusable excess of one of the two carbonyl compounds formed. The method according to the invention thus offers a substantial advantage of the possibility of adapting the production to the outlets for valuable phenol, acetone and MEK products, in particular the predicted overcapacity of acetone can be avoided.

Because the conversion of the mixture containing cumene and up to 25 wt. sec-butylbenzene, in view of the mixture according to the invention, can be carried out under the conditions known from the traditional cumene process, the process according to the invention is furthermore feasible quickly and easily in existing plants operating according to the cumene process. Preference is given to using plant parts from the past in oxidation and fission applications; adaptations are necessary only when starting materials are fed and in particular when the stream of fission products is processed into individual valuable products. The existing phenol and acetone operating equipment according to the traditional cumene process can therefore be easily expanded to be suitable for carrying out the process of the invention and operating according to the invention according to the market situation or only for the production of phenol and acetone.

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Thus, a mixture which contains up to 25% by weight, preferably up to 20% by weight, particularly preferably 10 to 20% by weight, of sec-butylbenzene, in addition to cumene according to the invention, serves as the starting material for oxidation. This mixture may already be pre-stored in a storage tank or formed by mixing from separate sources only before entering the oxidation reactors. Also, streams of cumene or sec-butylbenzene containing substances can be fed into the oxidation reactors and mixed there.

Preferably, the mixture of the starting materials according to the invention for oxidation is directly produced by alkylation of benzene with the appropriate mixture of propene and 1-butene / 2-butene in the presence of a commercially available alkylation catalyst, for example AlCl 3, H 3 PO 4 / S1O2 or zeolites. The gaseous mixture containing propene, 1-butene and 2-butene can be taken directly from the cracker, whereby the additional separation of the gaseous mixture into propene and 1-butene / 2-butene, for example for separate production of cumene and sec-butylbenzene, can be omitted.

Preference is given to bubbling reactors known from the cumene process. The oxidation is then carried out in a manner similar to that of the cumene process, preferably without catalyst, at temperatures of from 100 to 140 ° C and an absolute pressure of from 1 to 2 MPa in the presence of preferably oxygen or oxygen-containing gas in the form of molecular oxygen. peroxide content in the oxidation product stream up to 40 wt. The remainder mainly contains unreacted cumene and sec-butylbenzene because a very pure mixture of cumene and sec-butylbenzene is used. Furthermore, it is contained in small amounts of several by-products formed in the oxidation. These include, in particular, dimethylphenylmethanol, 2-phenylbutanol, acetophenone and propiophenone.

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As in the traditional cumene process, the oxidation product stream can be fed directly or through a collector as an intermediate tank to a thickening unit, preferably by distillation under vacuum by separating unreacted cumene and / or sec-butylbenzene to preferably 40-65% by weight of cumene hydroperoxide. and / or a content of sec-butylbenzene hydroperoxide to preferably 5 to 15 wt. in the stream of substances. The separated cumene and / or sec-butylbenzene is preferably returned to the oxidation, if necessary after further processing.

The stream of concentration substances is now fed to the cleavage, which according to the invention is preferably carried out under acid catalysis, in particular with sulfuric acid, in a homogeneous phase. Cumene hydroperoxide and sec-butylbenzene hydroperoxide are essentially converted here to phenol, acetone and MEK. Suitable cleavage reactors and suitable reaction conditions are known, for example, from EP-0 589 588 A1 or WO 97/06905. Advantageously, the cleavage product, as in the method of these patent documents, may be subjected to additional tempering to reduce the content of undesirable byproducts which increase yield. Thereafter, preferential distillation treatment of the mixture of cleavage products is carried out in a manner similar to the cumene method well known to the skilled person to isolate valuable phenol, acetone and MEK products.

The process of the invention is not limited to the main process steps outlined herein; on the contrary, all variants of the process known from the cumene process, supplementation or re-shifting can also be transferred to the process according to the invention, in particular when they are aimed at reducing by-product formation and optimizing energy consumption. In the knowledge of the method according to the invention, 9 < tb > < tb >

9 9 9 9 9 9999 9 9 9 reveal a variety of technological and instrumental embodiments to the skilled person on the background of the cumene process.

With the process according to the invention, yields of cleavage of phenol, acetone and MEK above 90% can be achieved. The composition of the mixture of starting materials used for the oxidation is adjusted in view of its content of sec-butylbenzene, preferably so that there are always sufficient sales outlets for the valuable acetone and MEK products which are produced as phenol-associated products. In this way, overcapacity losses are avoided and high efficiency is achieved.

The process according to the invention is illustrated in more detail by the following example without being limited to this example.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

A mixture consisting of 80 wt. % cumene and 20 wt. The sec-butylbenzene is oxidized by oxygen in a thermostat bubbler reactor at 132 ° C. After an oxidation time of 2.5 hours, the oxidation product according to gas chromatographic analysis (GC analysis) contains 21.5 wt. % of cumene hydroperoxide and 2.9 wt. sec-butylbenzene hydroperoxide. This mixture was then concentrated under high vacuum, the resulting concentrate containing 59.3 wt. % of cumene hydroperoxide and 8.1 wt. sec-butylbenzene hydroperoxide. The hydrocarbon mixture produced as a distillate contains less than 1% peroxide calculated as cumene hydroperoxide. The concentrate is then cleaved at 50 ° C in a single-phase cleavage in the presence of 2,000 ppm of acid.

sulfur dioxide dissolved in acetone or in a cleavage test product consisting of acetone, MEK, phenol and hydrocarbons.

The cleavage yield is evaluated. GC analysis for acetone above 95%, for MEK 92.3% and for phenol above 99%.

Claims (12)

PATENT CLAIMS A process for the production of phenol, acetone and methyl ethyl ketone by oxidizing a mixture comprising cumene and sec-butylbenzene with a molecular oxygen-containing gas followed by Hock cleavage of cumene hydroperoxide and sec-butylbenzene hydroperoxide, characterized in that the mixture comprising cumene and sec-butylbenzene contains up to 25 wt. sec-butyl benzene. The process according to claim 1, wherein the mixture comprises up to 20 wt. sec-butyl benzene. The process according to claim 2, wherein the mixture comprises 10 to 20 wt. sec-butylbenzene. Method according to at least one of the preceding claims, characterized in that the mixture consists of high purity cumene and high purity sec-butylbenzene. Process according to at least one of the preceding claims, characterized in that the mixture is produced by alkylating benzene with a gas mixture comprising propene, 1-butene and 2-butene. Method according to at least one of the preceding claims, characterized in that the oxidation is carried out with air or oxygen-containing gas in the form of molecular oxygen. 99 9999 • 999 999 e 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9 9999 99 9900 99 Process according to at least one of the preceding claims, characterized in that the oxidation is carried out at temperatures of 100 ° C to 140 ° C. Process according to at least one of the preceding claims, characterized in that the oxidation product is concentrated by distillation of the cumene or sec-butylbenzene, or both, prior to cleavage. A process according to claim 8, characterized in that the separated cumene or sec-butylbenzene or both are recycled to the oxidation. Method according to at least one of the preceding claims, characterized in that the cleavage mixture is homogeneous. Process according to at least one of the preceding claims, characterized in that the cleavage is acid catalysed. Process according to claim 11, characterized in that sulfuric acid is used as the acid.