RU2267476C1 - Ethylbenzene production process - Google Patents

Abstract

FIELD: industrial organic synthesis.

SUBSTANCE: alkylation of benzene with ethylene is carried out by supplying dried benzene feed, aluminum chloride-based catalytic complex, ethylene, recycled catalytic complex, and return benzene to alkylation reactor; separating resulting reaction medium from catalytic complex; neutralizing reaction medium with alkali; and flushing with water alkali; followed by rectification separation of reaction medium. According to invention, reaction components are preliminarily mixed in turbulent mode and fed into alkylation reactor also under turbulent conditions.

EFFECT: increased degree of benzene conversion.

2 ex

Description

The invention relates to the field of petrochemistry, specifically to a process for producing ethylbenzene by alkylation of benzene with ethylene in the presence of a catalytic complex based on aluminum chloride.

A known method of producing ethylbenzene, including the alkylation of benzene with ethylene in the presence of aluminum chloride, the separation of the target product by distillation from unreacted benzene and hydrocarbon impurities, azeotropic drying of a mixture of starting benzene with unreacted benzene and hydrocarbon impurities with the release of dried benzene, recycled, fractionated to alkyl, hydrocarbon impurities and benzene, which is subjected to condensation to obtain hydrocarbon and water layers (AS USSR No. 8 25466, IPC С 07 С 2/58, 15/02, publ. 30.04.81).

The disadvantage of this method is the increased consumption of aluminum chloride and benzene.

A known method of producing ethylbenzene by alkylation of benzene with ethylene in the presence of a catalytic complex based on aluminum chloride (T.V. Bashkatov, Ya.L. Zhigalin. "Technology of synthetic rubbers", M., "Chemistry", 1980, pp. 108-112). The catalytic complex obtained from aluminum chloride, ethyl chloride, diethylbenzene and benzene is continuously fed to the lower part of the alkylation reactor, where dried fresh and return benzene is continuously fed, as well as ethylene, diethylbenzene saturated with benzene and a recycle catalytic complex. Liquid benzene alkylation products from the upper part of the reactor enter the sump, where they are separated into two layers. The lower layer — the catalytic complex — is returned to the reactor, the upper layer — the alkylate — is mixed with water to destroy the residues of the catalytic complex, neutralized with an aqueous alkali solution, and washed from alkali. Next, the alkylate is subjected to three-stage rectification with the release of unreacted benzene in the first column and its return to the alkylation reactor, with the isolation of the target product ethylbenzene in the second column and diethylbenzene returned to the reactor for dealkylation and polyalkylbenzenes sent to the warehouse.

The disadvantage of this method of producing ethylbenzene is not a sufficiently high conversion of the process - 90-95% for benzene and about 93% for ethylene.

A known method of producing ethylbenzene, including the alkylation of benzene with ethylene in the presence of a catalytic complex based on aluminum chloride and rectification of the reaction mixture (P.A. Kirpichnikov, V.V. Beresnev, L.M. Popova. "Album of technological schemes of the main industries of the synthetic rubber industry" . L., "Chemistry", 1986, pp. 94-97). A dried benzene charge, a fresh and recycle catalytic complex, a fraction of polyalkylbenzenes and ethyl chloride, ethylene are fed directly to the lower part of the reactor through the collector through the collector. From the alkylator, the reaction mass is sent to a settling tank for separation from the circulating catalytic complex and then to water washing, neutralization with an alkali solution and water washing from alkali. The washed reaction mass is fed to the separation by distillation to isolate unreacted benzene in the first column, ethylbenzene rectified in the second column and the fraction of polyalkylbenzenes in the third distillation column.

The disadvantage of this method is the poor mixing of the components supplied to the alkylation reactor, and, as a consequence, the low conversion of the process.

The objective of the invention is to increase the conversion of the process of producing ethylbenzene.

The problem is solved by developing a method for producing ethylbenzene, including the alkylation of benzene with ethylene by feeding a dried benzene charge, a catalytic complex based on aluminum chloride, ethylene, a recycle catalytic complex and return benzene to an alkylation reactor, separating the resulting reaction mass from the catalytic complex, neutralizing the reaction mass with alkali and washing with water from alkali, followed by separation of the reaction mixture by distillation, while before feeding into the reactor p alkylation, the dried benzene charge, catalytic complex, ethylene, recycle catalytic complex and return benzene are mixed in turbulent mode and fed to the alkylation reactor also under turbulent conditions.

The difference between the proposed method and the known ones is that before feeding the dried benzene charge, catalytic complex, ethylene, recycle catalytic complex and return benzene to the alkylation reactor, they are mixed under turbulent conditions and they are also fed into the alkylation reactor under turbulence conditions.

As a device with which it is possible to achieve turbulent mixing of flows and impart turbulent motion to them, for example, a volumeless mixer equipped with confuser-diffuser sections, Rashig rings loaded in the pipe, or any other known means made of chemically resistant can be used materials or with a protective chemically resistant coating.

According to the proposed method, ethylbenzene is prepared as follows.

The process of alkylation of benzene with ethylene is carried out in a column-type alkylation reactor at a temperature of 125-140 ° C and an upper pressure of 0.12-0.25 MPa. A dried benzene charge, a catalytic complex based on aluminum chloride, ethylene, a recycled catalyst complex and recycled benzene are continuously fed to the lower part of the alkylation reactor by means of a turbulizing device. All components are mixed in turbulent mode and enter the reactor under turbulent flow conditions. From the alkylation reactor, the reaction mass is fed to the sump for settling of the circulating catalytic complex. The settled recycle catalytic complex is discharged from the bottom of the sump and returned to the alkylation reactor. To maintain the activity of the catalytic complex, ethyl chloride is fed into the line of the recycled catalytic complex. Next, the reaction mass enters the mixer, where it is mixed with acidic water in a ratio of water: reaction mass of at least 1: 1. Sludge of the reaction mixture from water occurs in the sump, from where the top layer - the reaction mixture - enters the wash column for washing with water and then neutralized with a 2-10% alkali solution. The neutralized reaction mass enters the column for washing with water from alkali. Washing the reaction mixture from alkali can be done with water or steam condensate. The washed reaction mass is fed to the separation in the first distillation column, where the unreacted benzene is separated by distillation, which is fed to the drying line. The bottoms product of the first column enters the second distillation column. The distillate column is used to isolate the target product, ethylbenzene, and the bottom product is fed to the third distillation column, where the fractions of diethylbenzene and polyalkylbenzenes are isolated.

The implementation of the method is illustrated by the following examples.

Example 1

A dried benzene charge, an aluminum chloride-based catalytic complex, ethylene, a recycled catalyst complex and recycled benzene are continuously fed to the lower part of the alkylation reactor through a volumeless mixer equipped with diffuser-confuser sections. All components are mixed in turbulent mode and enter the reactor under turbulent flow conditions. The process of alkylation of benzene with ethylene is carried out in a column-type alkylation reactor at a temperature of 130 ° C and an upper pressure of 0.20 MPa. From the alkylation reactor, the reaction mass enters the sump to sediment the circulating catalytic complex. The settled recycle catalytic complex is discharged from the bottom of the sump and returned to the alkylation reactor. Next, the reaction mass enters the mixer, where it is mixed with acidic water in a ratio of water: reaction mass of at least 1: 1. Sludge of the reaction mixture from water occurs in the sump, from where the top layer - the reaction mixture - enters the wash column for washing with water and then neutralized with a 2-10% alkali solution. The volume ratio of alkali solution to the reaction mass is maintained equal to 1: 1. The neutralized reaction mass enters the column for washing with water from alkali. The washed reaction mass is fed to the separation in the first distillation column, where the unreacted benzene is separated by distillation, which is fed to the drying line. The bottoms product of the first column enters the second distillation column. The distillate of the column isolated the target product is ethylbenzene containing 99.8% wt. ethylbenzene, and the bottoms product is fed into the third distillation column, where fractions of diethylbenzene and polyalkylbenzenes are isolated as distillate. The conversion of the process for benzene is 97%, for ethylene - 95%.

Example 2

Ethylbenzene is obtained in the same manner as described in example 1, but the mixture of the dried benzene charge, catalytic complex, ethylene, recycle catalytic complex and return benzene is carried out in a pipe filled with Raschig rings before being fed to the alkylation reactor.

The conversion of the process for benzene is 98%, for ethylene - 95.5%.

As can be seen from the above examples, preliminary mixing of the dried benzene charge, catalytic complex, ethylene, recycle catalytic complex, and return benzene under turbulent conditions before feeding to the alkylation reactor and supplying all components for alkylation under turbulence conditions allow achieving high conversion rates for ethylbenzene production.

Claims (1)

A method of producing ethylbenzene, including the alkylation of benzene with ethylene by feeding a dried benzene charge, a catalytic complex based on aluminum chloride, ethylene, a recycle catalytic complex and recycled benzene to an alkylation reactor, separating the resulting reaction mass from the catalytic complex, neutralizing the reaction mass with alkali and washing with water from alkali followed by separation of the reaction mass by distillation, characterized in that before feeding into the alkylation reactor carry out Mechain dried benzene charge, catalytic complex of ethylene, the recycle of the catalytic complex and return the benzene in the turbulent regime and fed them to the alkylation reactor in turbulent conditions.