Technology for the joint production of styrene and propylene oxide

The general technological scheme for the joint production of styrene and propylene oxide is shown in Fig. 3. In this technology, the oxidation of ethylbenzene is carried out in a plate column 1. In this case, both heated ethylbenzene and air are supplied to the bottom of the column. The column is equipped with coils located on plates. The heat is removed by the water supplied to these coils. If a catalyst is used to intensify the process, then the process must be carried out in a series of series-connected bubble reactors into which an ethylbenzene charge (a mixture of fresh and recycled ethylbenzene with a catalyst solution) is supplied countercurrently to the air. In this case, the oxidation products pass sequentially through reactors, each of which is supplied with air.

The vapor-gas mixture from the upper part of the reactor enters condenser 2, in which mainly entrained ethylbenzene, as well as impurities of benzoic and formic acids, are condensed. After separating the condensate from the cans, it is sent to scrubber 4 to neutralize acids with alkali. After neutralization, ethylbenzene is returned to reactor C 1. Ethylbenzene is also supplied there from column 10. Gases are removed from the system. The oxide from the bottom of column 1, containing about 10% hydroperoxide, is sent to distillation column 3 for concentration. Concentration of hydroperoxide is carried out under high vacuum. Despite the high energy costs, this process is best carried out in a double distillation unit. In this case, in the first column, part of the ethylbenzene is distilled off at a lower vacuum, and in the second column, at a deeper vacuum, the rest of the ethylbenzene with impurities is distilled off. The distillate of this column is returned to the first column, and in the cube a concentrated (up to 90%) hydroperoxide is obtained, which is sent for epoxidation. The oxidation is pre-cooled in heat exchanger 5 with the original ethylbenzene.

Rice. 4. Technological scheme for the joint production of styrene and propylene oxide; 1 - oxidation column; 2 - capacitor; 3.7-10.18 - distillation columns; 4 - alkaline scrubber; 5,12,14 - heat exchangers; 6 - epoxidation column; 11 - mixing evaporator; 13,15 - dehydration reactors; 16 - refrigerator; 17 - Florentine vessel; I - air; II - ethylbenzene; III -propylene; IV - alkali solution; V - gases; VI - catalyst solution; VII -propylene oxide; VIII - resins; IX - water layer; X - styrene; XI - for dehydrogenation; XII-pairs

In column 3, ethylbenzene with acid impurities is distilled off, so the upper product is also sent to scrubber 4. From the bottom of column 3, concentrated hydroperoxide enters epoxidation column 6. (Epoxidation can also be carried out in a cascade of reactors.) A catalyst solution is supplied to the lower part of the column - a mash solution from cube of column 9. Fresh catalyst is also fed there. Fresh and return (from column 7) propylene is also supplied to the lower part of the column. The reaction products, together with the catalyst solution, are removed from the top of the column and sent to distillation column 7 for distillation of propylene. Gases are removed from the top of the column and from the system for disposal or combustion. The bottom product of column 7 enters the distillation column 8 to isolate product propylene oxide as a distillate. The bottom liquid of column # enters column 9 to separate synthesis products from the catalyst solution.

The catalyst solution from the bottom of the column is returned to the epoxidation column 6, and the upper product enters the Yull distillation column for separating ethylbenzene from methylphenylcarbinol and acetophenone. A mixture of methylphenylcarbinol (MPC) and acetophenone is fed into evaporator 11, in which methylphenylcarbinol and acetophenone are evaporated and separated from the resins using superheated steam. The vapor mixture, superheated to 300 °C, enters reactor 13 for dehydration of methylphenylcarbinol. Partial dehydration takes place in this reactor. Since the dehydration reaction is endothermic, before the dehydration products enter another reactor (reactor 15), the dehydration products are overheated in heat exchanger 14.

The conversion of methylphenylcarbinol after two reactors reaches 90%. The dehydration products are cooled with water in the refrigerator 76 and enter the Florentine vessel 17, in which the organic layer is separated from the aqueous one. The upper hydrocarbon layer enters the distillation column 18 to separate styrene from acetophenone. Acetophenone is then hydrogenated in a separate plant into methylphenylcarbinol, which enters the dehydration department.

The selectivity of the process for propylene oxide is 95-97%, and the yield of styrene reaches 90% for ethylbenzene. In this case, from 1 ton of propylene oxide, 2.6-2.7 tons of styrene are obtained.

Thus, the technology considered represents a complex system, including many recycles of ethylbenzene, propylene and catalyst. These recycles lead, on the one hand, to an increase in energy costs, and on the other, they allow the process to be carried out in safe conditions (at a low concentration of hydroperoxide - 10-13%) and achieve complete conversion of the reagents: ethylbenzene and propylene.

Hence, this process needs to be optimized. The proposed technological scheme makes full use of the heat of reactions and flows. However, instead of refrigerator 16, it is better to use a waste heat boiler in which steam can be produced low pressure. To do this, it is necessary to supply water condensate to the waste heat boiler, from which steam will be produced. In addition, it is necessary to provide for a more complete use of waste gases and resin, an alkaline solution of salts from scrubber 4, as well as additional purification of the water layer of the Florentine vessel. The most significant improvement in the technological scheme can be the replacement of dehydration reactors with a column in which a combined reaction-distillation process can be organized. This process takes place on an ion exchange catalyst in the vapor-liquid version, i.e. at the boiling point of the mixtures passing through the column, and can be represented by a diagram (Fig. 5).

Rice. 5.

In this version of the process, conversion and selectivity can reach 100%, since the process occurs at low temperatures and short residence time of the synthesis products in the reactor. The advantage of this process option is also that styrene does not enter the column bottom, but is released in the form of a heteroazeotrope with water (boiling point below 100 °C), which eliminates its thermopolymerization .

Use: petrochemistry. Essence: alkylation of benzene with ethylene is carried out by feeding a dried benzene charge, a catalytic complex based on aluminum chloride, ethylene, a recirculating catalytic complex and return benzene into an alkylation reactor, separating the resulting reaction mass from the catalytic complex, neutralizing the reaction mass with alkali and washing the alkali with water, followed by separation of the reaction mass by rectification. In this case, before feeding into the alkylation reactor, the dried benzene charge, catalytic complex, ethylene, recirculating catalytic complex and return benzene are mixed in a turbulent mode and fed into the alkylation reactor also under turbulent conditions. Technical result: increasing the conversion of the ethylbenzene production process.

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

There is a known method for producing ethylbenzene, including alkylation of benzene with ethylene in the presence of aluminum chloride, separation of the target product by rectification from unreacted benzene and hydrocarbon impurities, azeotropic drying of a mixture of initial benzene with unreacted benzene and hydrocarbon impurities with the release of dried benzene, recycled for alkylation, and a fraction containing water , hydrocarbon impurities and benzene, which is subjected to condensation to produce hydrocarbon and aqueous layers (A.S. USSR No. 825466, IPC C 07 C 2/58, 15/02, publ. 04/30/81).

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

There is a known method for 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 derived from aluminum chloride, ethyl chloride, diethylbenzene and benzene is continuously fed to the bottom of the alkylation reactor, which continuously receives dried fresh and recycled benzene, as well as ethylene, diethylbenzene saturated with benzene, and recirculating catalyst complex. Liquid benzene alkylation products from the upper part of the reactor enter the settling tank, where they are separated into two layers. The bottom layer - the catalytic complex - is returned to the reactor, the top layer - the alkylate - is mixed with water to destroy the residues of the catalytic complex, for neutralization aqueous solution alkali and alkali cleaning. Next, the alkylate undergoes a three-stage rectification with the separation of unreacted benzene in the first column and its return to the alkylation reactor, with the release of the target product - ethylbenzene - in the second column and in the third column - diethylbenzene, returned to the reactor for dealkylation, and polyalkylbenzenes sent to the warehouse.

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

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

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

The objective of the invention is to increase the conversion of the process for 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 recirculating catalytic complex and return benzene into the 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 rectification, while before feeding it into the alkylation reactor, the dried benzene charge, catalytic complex, ethylene, recirculating catalytic complex and return benzene are mixed in a turbulent mode and fed into the alkylation reactor, also under turbulent conditions.

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

As a device with which you can achieve turbulent mixing of flows and give them turbulent movement, you can use, for example, a volumeless mixer equipped with confuser-diffuser sections, or Raschig rings loaded into a pipe, or any other known means made of chemically resistant materials or with a protective chemical-resistant coating.

According to the proposed method, ethylbenzene is obtained 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 a top pressure of 0.12-0.25 MPa. Dried benzene charge, a catalytic complex based on aluminum chloride, ethylene, a recirculating catalytic complex and return benzene are continuously fed into the lower part of the alkylation reactor through a turbulizing device. All components are mixed in a turbulent mode and enter the reactor under conditions of turbulent flow. From the alkylation reactor, the reaction mass is fed into a settling tank to settle the circulating catalytic complex. The settled recirculated catalytic complex is removed from the bottom of the settling tank and returned to the alkylation reactor. To maintain the activity of the catalytic complex, ethyl chloride is supplied to the recirculated catalytic complex line. Next, the reaction mass enters the mixer, where it is mixed with acidic water in a water:reaction mass ratio of at least 1:1. The reaction mass settles from the water in a settling tank, from where the top layer - the reaction mass - enters the washing column for washing with water and then for neutralization with a 2-10% alkali solution. The neutralized reaction mass enters the column to be washed from the alkali with water. Washing the reaction mass from alkali can be done with water or steam condensate. The washed reaction mass is fed into the first distillation column for separation, where unreacted benzene is separated out as a distillate and sent for drying. The bottom product of the first column enters the second distillation column. The target product, ethylbenzene, is isolated from the distillate of the column, and the bottom product is fed into the third distillation column, where fractions of diethylbenzene and polyalkylbenzenes are isolated as a distillate.

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

Dried benzene mixture, a catalytic complex based on aluminum chloride, ethylene, a recirculating catalytic complex and return benzene are continuously fed into the lower part of the alkylation reactor through a volumeless mixer equipped with diffuser-confuser sections. All components are mixed in a turbulent mode and enter the reactor under conditions of turbulent flow. The process of alkylation of benzene with ethylene is carried out in a column-type alkylation reactor at a temperature of 130°C and a top pressure of 0.20 MPa. From the alkylation reactor, the reaction mass enters the settling tank to settle the circulating catalytic complex. The settled recirculated catalytic complex is removed from the bottom of the settling tank and returned to the alkylation reactor. Next, the reaction mass enters the mixer, where it is mixed with acidic water in a water:reaction mass ratio of at least 1:1. The reaction mass settles from the water in a settling tank, from where the top layer - the reaction mass - enters the washing column for washing with water and then for neutralization with a 2-10% alkali solution. The volume ratio of the alkali solution to the reaction mass is maintained at 1:1. The neutralized reaction mass enters the column to be washed from the alkali with water. The washed reaction mass is fed into the first distillation column for separation, where unreacted benzene is separated out as a distillate and sent for drying. The bottom product of the first column enters the second distillation column. The distillate of the column releases the target product - ethylbenzene, containing 99.8% wt. ethylbenzene, and the bottom product is fed into the third distillation column, where fractions of diethylbenzene and polyalkylbenzenes are separated as a distillate. The conversion of the process for benzene is 97%, for ethylene - 95%.

Ethylbenzene is produced in the same way as described in example 1, but the mixing of the dried benzene charge, catalytic complex, ethylene, recirculating catalytic complex and return benzene before feeding into the alkylation reactor is carried out in a pipe filled with Raschig rings.

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

As can be seen from the above examples, pre-mixing of the dried benzene charge, catalytic complex, ethylene, recirculating catalytic complex and return benzene under turbulent conditions before feeding into the alkylation reactor and feeding all components for alkylation under turbulent conditions makes it possible to achieve high performance conversion in the production of ethylbenzene.

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 recirculating catalytic complex and return benzene into an alkylation reactor, separating the resulting reaction mass from the catalytic complex, neutralizing the reaction mass with alkali and washing the alkali with water followed by separation of the reaction mass by rectification, characterized in that before feeding into the alkylation reactor, the dried benzene charge, catalytic complex, ethylene, recirculating catalytic complex and return benzene are mixed in a turbulent mode and fed into the alkylation reactor also under turbulent conditions.

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Ministry of General Education of the Russian Federation

KAZAN STATE TECHNOLOGICAL

UNIVERSITY

NIZHNEKAMSK CHEMICAL-TECHNOLOGICAL

INSTITUTE

Department of Chemical technologies

Group

Course project

Subject: Preparation of ethylbenzene by alkylation of benzene with ethylene

Student:

Supervisor (_________)

Student ka (_________)

Nizhnekamsk

INTRODUCTION

The topic of this course project is the production of ethylbenzene by the alkylation of benzene with ethylene.

The most common petrochemical synthesis process is the catalytic alkylation of benzene with olefins, which is determined by the high demand for alkyl aromatic hydrocarbons - raw materials in the production of synthetic rubbers, plastics, synthetic fibers, etc.

Alkylation is the process of introducing alkyl groups into mo- molecules of organic and some inorganic substances. These reactions are of great practical importance for the synthesis of alkyl aromatic compounds, iso-alkanes, amines, mercaptans and sulfides, etc.

The alkylation reaction of benzene with alkyl chlorides in the presence of anhydrous aluminum chloride was first carried out in 1877 by S. Friedel and J. Crafts. In 1878, Friedel's student Balson obtained ethylbenzene by alkylation of benzene with ethylene in the presence of ALCL3.

Since the discovery of the alkylation reaction, many various methods replacement of hydrogen atoms of benzene and other aromatic hydrocarbons with alkyl radicals. For this purpose, various alkylation agents and catalysts have been used 48,49.

The alkylation rate of aromatic hydrocarbons is several hundred times higher than that of paraffins, so the alkyl group is almost always directed not to the side chain, but to the core.

For the alkylation of aromatic hydrocarbons with olefins, numerous catalysts of the nature of strong acids are used, in particular sulfuric acid(85-95%), phosphoric and pyrophosphoric acids, anhydrous hydrogen fluoride, synthetic and natural

aluminosilicates, ion exchangers, heteropolyacids. Acids in liquid form exhibit catalytic activity in alkylation reactions at low temperatures (5-100°C); acids on solid carriers, for example phosphoric acid on kieselguhr, act at 200-300°C; aluminosilicates are active at 300-400 and 500°C and pressure 20-40 kgf/cm² (1.96-3.92 MN/m²).

The relevance of this topic is that styrene is subsequently obtained from ethylbenzene by dehydrogenation of ethylbenzene.

1. THEORETICAL PART

2.1 Theoretical basis of the adopted production method.

Alkylation of benzene with ethylene. Industrial processes for the alkylation of benzene with ethylene vary depending on the catalyst used. A number of catalysts have been tested on a pilot scale.

In 1943, Copers carried out the alkylation of benzene with ethylene on an aluminosilicate catalyst in the liquid phase at 310°C and 63 kgf/cm² (6.17 MN/m²) with a molar ratio of ethylene: benzene 1:4.

The process of alkylation of benzene with ethylene on aluminum chloride at atmospheric or slightly elevated pressure and a temperature of 80-100°C has become widespread.

Alkylation on a solid phosphoric acid catalyst competes with this method, but only isopropylbenzene can be obtained on this catalyst. Alkylation of benzene with ethylene is practically not carried out on it.

A large group of alkylation catalysts consists of aprotic acids (Lewis acids) - halides of certain metals. They usually exhibit catalytic activity in the presence of promoters, with which they form products that are strong protic acids. Catalysts of this type can be aluminum chloride, aluminum bromide, ferric chloride, zinc chloride, titanium trichloride and titanium tetrachloride. Only aluminum chloride has industrial use.

The following general ideas are held about the mechanism of alkylation reactions of benzene and its homologues with olefins.

Alkylation in the presence of aluminum chloride is interpreted mechanistically

mu acid catalysis. In this case, the system must contain

create a promoter, the role of which is played by hydrogen chloride. The latter can

formed in the presence of water:

CH3 CH=CH2 + H – CL ∙ ALCL3 ↔ CH3 – CH – CH3 ∙ CL ∙ ALCL3

Further addition to the aromatic ring occurs via a mechanism similar to that discussed above:

HCL(CH3)2 ∙CL∙ALCL3 +CH3 –CH–CH3 ∙CL∙ALCL3 →HCH(CH3)2 + CH(CH3)2 + CL ∙ ALCL3 + HCL + ALCL3

In the presence of aluminum chloride, dealkylation occurs easily, which indicates the reversibility of the alkylation reaction. Dealkylation reactions are used to convert polyalkylbenzenes into monoalkyl-

Thermodynamics of the alkylation reaction. Based on physico-chemical

constants of hydrocarbons and their thermodynamic functions - enthalpy ΔН and

entropy ΔS, you can find the equilibrium constants and calculate the equilibrium

yields of alkyl derivatives during alkylation of benzene with olefins, depending on

depending on temperature and pressure.

The equilibrium yield of ethylbenzene increases with increasing molar

excess benzene and with increasing pressure at a given temperature.

C6 H6 + C2 H4 ↔ C6 H5 C2 H5

When benzene is alkylated with ethylene at temperatures below 250-300°C

Almost complete conversion of benzene to ethylbenzene is achieved. At 450

-500°C to increase the depth of transformation requires an increase in pressure to 10-20 kgf/cm² (0.98-1.96 MN/m²).

The alkylation reaction of benzene with ethylene is a sequential, reversible first-order reaction. As the process deepens, along with monoalkylbenzene, polyalkylbenzenes are also formed

C6 H6 + Cn H2n ↔ C6 H5 Cn H2n+1

C6 H5 Cn H2n+1 + Cn H2n ↔ C6 H4 (Cn H2n+1)2 which are unwanted by-products. Therefore, the composition of the alkylate reaction mixture is more often determined by kinetic factors than by thermodynamic equilibrium.

Thus, dealkylation is thermodynamically possible with great depth at 50-100°C. Indeed, in the presence of aluminum chloride it proceeds well, since with this catalyst the alkylation process is reversible. However, at the same temperatures in the presence of acids, dealkylation does not occur at all. M.A. Dalin experimentally studied the composition of the products of benzene alkylation with ethylene in the presence of aluminum chloride.

The composition of the reaction mixture is determined by the ratio of benzene and ethylene and does not depend on how the alkylate is obtained: direct alkylation or dealkylation of polyalkylbenzene. However, this conclusion is valid only when aluminum chloride is used as a catalyst.

The alkylation process is carried out in an alkylator - a reaction column enameled or lined with graphite tiles for protection against corrosion. Three sections of the column have jackets for cooling, but the main amount of heat is removed by evaporation of some benzene. Alkylation is carried out in the presence of a liquid catalyst complex consisting of aluminum chloride (10-12%), benzene (50-60%) and polyalkylbenzenes (25-30%). To form hydrogen chloride, which is the promoter of the reaction, 2% water from

masses of aluminum chloride, as well as dichloroethane or ethyl chloride, the splitting of which produces hydrogen chloride.

To isolate ethylbenzene from the alkylate, benzene is distilled off at atmospheric pressure (traces of water are removed simultaneously with benzene). A wide fraction, a mixture of ethylbenzene and polyalkylbenzenes, is distilled from the bottom liquid at reduced pressure (200 mm Hg, 0.026 MN/m²). In the next column at a residual pressure of 50 mm Hg. (0.0065 MN/m²) polyalkylbenzenes are separated from the resins. The wide fraction is dispersed in a vacuum column at a residual pressure of 420-450 mm Hg. (0.054-0.058 MN/m²). Commercial ethylbenzene is distilled within the range of 135.5-136.2°C.

To produce ethylbenzene, ethane is used - the ethylene fraction of pyrolysis containing 60-70% ethylene.

Benzene for alkylation should contain no more than 0.003-0.006% water, while commercial benzene contains 0.06-0.08% water. Benzene dehydration is carried out by azeotropic distillation. The sulfur content in benzene should not exceed 0.1%. Increased sulfur content causes an increase in the consumption of aluminum chloride and deteriorates the quality of the finished product.

1.2. Characteristics of raw materials and the resulting product.

Name of raw materials, materials, reagents, catalysts. semi-finished products, manufactured products.	State number military or industry standard technical standard enterprises.	Quality indicators required for verification.	Norm (according to OST, stan- Dartu undertook	Purpose, application area.
1.ETHYLBENZENE	colorless transparent liquid. Main indicators of the properties of ethylbenzene: Molecular weight=106.17 Density, g/cm³ = 0.86705 Temperature, °C Boiling point = 176.1 Melting=-25.4 Flashing=20 Self-ignition = 431. Heat, kJ/mol Melting=9.95 Evaporation=33.85 Heat capacity, J/mol ∙ K=106.4 Heat of combustion, kcal/mol=1089.4 Solubility in water, g/100ml=0.014	In industry, it is used mainly as a raw material for the synthesis of styrene, as an additive to motor fuel, and as a diluent and solvent. C6 H5 C2 H5 Most of the ethylbenzene is obtained by alkylation of benzene with ethylene and a much smaller amount is isolated by ultra-high distillation from straight-run gasoline reforming products. Main indicators of the properties of ethylbenzene: Ethylbenzene irritates the skin, has convulsive action. The maximum permissible concentration in atmospheric air is 0.02 mg/m³, in water bodies household use – 0.01 mg/l. CPV 0.9-3.9% by volume. Volume of world production is about 17 million tons per year (1987). Production volume in Russia 0.8 million tons per year (1990).

H2 C=CH2. Colorless gas with a faint odor. Ethylene dissolves in water 0.256 cm³/cm³ (at 0 °C), dissolves in alcohols and ethers. Ethylene has the properties of phytohormones - it slows down growth, accelerates cell aging, ripening and fruit fall. It is explosive, CPV 3-34% (by volume), MPC in atmospheric air 3 mg/m³, in the air of the working area 100 mg/m³. World production 50 million tons per year (1988).

Contains in large quantities (20%) in oil refining gases; is part of coke oven gas. One of the main products of the petrochemical industry: used for the synthesis of vinyl chloride, ethylene oxide, ethyl alcohol, polyethylene, etc. Ethylene is obtained by processing oil and natural gas. Issue The flaxed ethylene fraction contains 90-95% ethylene with an admixture of propylene, methane, ethane. It is used as a raw material in the production of polyethylene, ethylene oxide, ethyl alcohol, ethanolamine, polyvinyl chloride, and in surgery for anesthesia.

C6 H6. Colorless liquid with a peculiar mild odor home Forms explosive mixtures with air, mixes well with ethers, gasoline and other organic solvents. Solubility in water 1.79 g/l (at 25 °C). Toxic, dangerous for environment, flammable. Benzene is an aromatic hydrocarbon. Main indicators of benzene properties: Molecular weight=78.12 Density, g/cm³=0.879 Temperature, °C: Boiling point=80.1 Melting=5.4 Flashes=-11 Self-ignition=562 Heat, kJ/mol: Melting=9.95 Evaporation=33.85 Heat capacity, J/mol ∙ K=81.6 Benzene is miscible in all respects with non-polar solvents: hydrocarbons, turpentine, ethers, dissolves fats, rubber, resins (tar). It produces an azeotropic mixture with water with a boiling point of 69.25 °C, and forms double and triple azeotropic mixtures with many compounds.

Found in some oils, motor fuels, gasolines. Widely used in industry, it is a raw material for the production of medicines, various plastics, synthetic rubber, and dyes. Benzene is a component of crude oil, but on an industrial scale it is mostly synthesized from its other components. It is also used for the production of ethylbenzene, phenol, nitrobenzene, chlorobenzene, as a solvent. Depending on the production technology, different grades of benzene are obtained. Petroleum benzene is obtained in the process of catalytic reforming of gasoline fractions, catalytic hydrodealkylation of toluene and xylene, as well as during the pyrolysis of petroleum feedstock.

2.3. Description of the technological scheme.

Appendix A presents a flow diagram for the production of ethylbenzene. The process of alkylation of benzene with ethylene is carried out in an alkylator pos. R-1 in an ethyl chloride environment at a temperature of 125-135C and a pressure of 0.26-0.4 MPa. The following are fed into the alkylator: dried benzene charge, catalytic complex, polyalkylbenzene fraction, ethylene, recirculating catalytic complex, return benzene.

The alkylation reaction releases heat, the excess amount of which is removed by the recirculating catalytic complex and evaporating benzene. Benzene from the upper part of the alkylator mixed with exhaust gas is sent to the condenser pos. T-1, water cooled. Non-condensed gases from the condenser pos. T-1 are sent to the capacitor pos. T-2, cooled with chilled water t=0°C. Vents after the condenser pos. T-2 is supplied for further recovery of benzene vapors. Benzene condensate from condensers pos. T-1 and T-2 flow by gravity into the bottom of the alkylator pos. R-1. From the alkylator pos. P-1 reaction mass through heat exchanger pos. T-3, where it is cooled with water to 40-60 °C, is sent to the settling tank pos. E-1 for separation from the circulating catalytic complex. The settled catalytic complex from the bottom of the settling tank pos. E-1 is taken up by pump pos. N-1 and returns to the alkylator pos. R-1. To maintain catalyst activity, ethyl chloride is supplied to the recirculating complex line. In the event of a decrease in catalyst activity, the spent catalytic complex is removed for decomposition. Reaction mass from the settling tank pos. E-1 is collected in container pos. E-2, from where, due to the pressure in the alkylation system, it enters the mixer pos. E-3 for mixing with acidic water circulating in the decomposition system:

settling tank pos. E-4-pump, pos. N-2-mixer, pos. E-3. The ratio of circulating water supplied to the mixer and the reaction mass is l/2: 1. In Yes, the decomposition system is supplied from a collection of items. E-5 pump pos. N-3. The reaction mass is settled from water in a settling tank, pos. E-4; lower water layer with pump pos. N-2 is sent to the mixer; and the top layer - the reaction mass - flows by gravity into the washing column pos. K-1 for secondary flushing with water supplied by pump pos. N-4 from the washing column pos. K-2. From the washing column pos. K-1 reaction mass flows by gravity into the collection pos. E-6, from where the pump pos. N-5 is pumped out for neutralization into the mixer pos. E-7.

The lower water layer from the washing column pos. K-1 is drained by gravity into the container pos. E-5 and pump pos. N-3 is fed into the mixer pos. E-3. Neutralization of the reaction mass in the mixer pos. E-7 is carried out with a 2-10% solution of sodium hydroxide. The ratio of the reaction mass and the circulating sodium hydroxide solution is 1:1. The separation of the reaction mass from the alkali solution occurs in the settling tank, pos. E-8, from where the reaction mass flows by gravity into the column pos. K-2 for cleaning from alkali with water condensate. The bottom layer - chemically contaminated water - is drained from the column into a container pos. E-9 and pump pos. N-4 is pumped out for washing the reaction mass into the column pos. K-1. The reaction mass from the top of the column flows by gravity into the settling tank pos. E-10, then collected in an intermediate container, pos. E-11 and is pumped out by pump pos. N-7 to the warehouse.

Technological scheme for the alkylation of benzene with ethylene on aluminum chloride, also suitable for the alkylation of benzene with propylene.

The alkylation process is carried out in an alkylator - a reaction column enameled or lined with graphite tiles for corrosion protection. Three sections of the column have jackets for cooling, but the main amount of heat is removed by evaporation of some benzene. Alkylation is carried out in the presence of a liquid catalyst complex consisting of aluminum chloride (10–12%), benzene (50–60%) and

polyalkylbenzenes (25 – 30%). To form hydrogen chloride, which is the promoter of the reaction, 2% water by weight of aluminum chloride is added to the catalytic complex, as well as dichloroethane or ethyl chloride, the cleavage of which produces hydrogen chloride.

1.5. Description of devices and operating principle of the main apparatus.

Alkylation is carried out in a column reactor without mechanical stirring at a pressure close to atmospheric (Appendix B). The reactor consists of four frames, enameled or lined with ceramic or graphite tiles. For better contact there is a nozzle inside the reactor. The height of the reactor is 12 m, the diameter is 1.4 m. Each drawer is equipped with a jacket for heat removal during normal operation of the reactor (it is also used for heating when starting the reactor). The reactor is filled to the top with a mixture of benzene and catalyst. Dried benzene, catalytic complex and ethylene gas are continuously fed into the lower part of the reactor. The liquid products of the alkylation reaction are continuously withdrawn at a height of approximately 8 m from the base of the reactor, and a vapor-gas mixture consisting of unreacted gases and benzene vapor is removed from the top of the reactor. The temperature in the lower part of the reactor is 100°C, in the upper part it is 90 - 95°C. The catalyst complex is prepared in an apparatus from which a catalyst suspension is continuously fed into the alkylation reactor.

The alkylator for producing ethylbenzene in the liquid phase is a steel column lined inside with an acid-resistant lining pos. 4 or coated with acid-resistant enamel to protect the walls from corrosive action of hydrochloric acid. The device has four drawer positions. 1, connected by flanges pos. 2. Three drawers are equipped with shirts pos. 3 for cooling with water (to remove heat during the alkylation reaction). During operation, the reactor is filled with reaction liquid, the column height of which is 10 m . Above the liquid level, two coils are sometimes placed in which water circulates for additional cooling.

The operation of the alkylator is continuous: benzene, ethylene and the catalytic complex are constantly supplied to its lower part; the mixture of reactants and catalyst rises into top part apparatus and from here flows into the sump. The vapors coming from the top of the alkylator (consisting primarily of benzene) condense and return to the alkylator as a liquid.

In one pass, ethylene reacts almost completely, and benzene only 50-55%; therefore, the yield of ethylbenzene in one pass is about 50% of the theoretical; the rest of the ethylene is lost to the formation of di- and polyethylbenzene.

The pressure in the alkylator during operation is 0.5 at(excessive), temperature 95-100°C.

Alkylation of benzene with ethylene can also be carried out in the gas phase over a solid catalyst, but this method is still little used in industry.

The yield of ethylbenzene is 90–95% based on benzene and 93% based on ethylene. Consumption per 1 ton of ethylbenzene is: ethylene 0.297 tons,

benzene 0.770 t, aluminum chloride 12 - 15 kg.

2. CONCLUSIONS ON THE PROJECT.

The cheapest ethylbenzene is obtained by isolating it from the xylene fraction of reforming or pyrolysis products, where it is contained in an amount of 10-15%. But the main method for producing ethylbenzene remains the method of catalytic alkylation of benzene.

Despite the presence of large-scale production of alkylbenzenes, there are a number of unsolved problems that reduce the efficiency and technical and economic indicators of alkylation processes. The following disadvantages can be noted:

Lack of stable, highly active catalysts for the alkylation of benzene with olefins; catalysts that are widely used - aluminum chloride, sulfuric acid, etc. cause corrosion of equipment and are not regenerated;

The occurrence of secondary reactions that reduce the selectivity of the production of alkylbenzenes, which requires additional costs for the purification of the resulting products;

Education large quantity wastewater and industrial waste using existing alkylation technological schemes;

Insufficient unit production capacity.

Thus, due to the high value of ethylbenzene, there is currently a very high demand for it, while its cost is relatively low. The raw material base for the production of ethylbenzene is also wide: benzene and ethylene are obtained in large quantities by cracking and pyrolysis of petroleum fractions.

3. STANDARDIZATION

The following GOSTs were used in the course project:

GOST 2.105 – 95 General requirements for text documents.

GOST 7.32 – 81 General requirements and rules for preparing coursework and dissertations.

GOST 2.109 – 73 Basic requirements of the drawing.

GOST 2.104 – 68 Basic inscriptions on drawings.

GOST 2.108 – 68 Specifications.

GOST 2.701 – 84 Schemes, types, types, general requirements.

GOST 2.702 – 75 Rules for the implementation of schemes various types.

GOST 2.721 – 74 Symbols and graphical symbols in diagrams.

GOST 21.108 – 78 Conditional and graphic image on the drawings.

GOST 7.1 – 84 Rules for preparing a list of references.

4. LIST OF REFERENCES USED.

1. Traven V.F. Organic chemistry: in 2 volumes: textbook for universities / V.F. Traven. – M.: NCC Akademkniga, 2005. – 727 p.: ill. – Bibliography: p. 704 – 708.

2. Epshtein D.A. General chemical technology: textbook for vocational schools / D.A. Epstein. – M.: Chemistry, - 1979. – 312 p.: ill.

3. Litvin O.B. Fundamentals of rubber synthesis technology. / ABOUT. Litvin. – M.: Chemistry, 1972. – 528 p.: ill.

4. Akhmetov N.S. General and inorganic chemistry: textbook for universities - 4th ed., revised. / N.S. Akhmetov. – M.: Higher School, ed. Center Academy, 2001. – 743 pp.: ill.

5. Yukelson I.I. Technology of basic organic synthesis. / I.I. Yukelson. – M.: Chemistry, -1968. – 820 pp.: ill.

6. Paushkin Ya.M., Adelson S.V., Vishnyakova T.P. Petrochemical synthesis technology: part 1: Hydrocarbon raw materials and their oxidation products. / Ya.M. Paushkin, S.V. Adelson, T.P. Vishnyakova. – M.: Chemistry, -1973. – 448 p.: ill.

7. Lebedev N.N. Chemistry and technology of basic organic and petrochemical synthesis: textbook for universities - 4th ed., revised. and additional / N.N. Lebedev. – M.: Chemistry, -1988. – 592 p.: ill.

8. Plate N.A., Slivinsky E.V. Fundamentals of chemistry and technology of monomers: textbook. / N.A. Plate, E.V. Slivinsky. – M.: MAIK Science / Interperiodics, -2002. – 696 p.: ill.

Introduction…………………………………………………………………………………3

2. Technological part……………………………………………………….

2.1. Theoretical basis of the adopted production method………….5

2.2. Characteristics of raw materials and the resulting product…………………..9

2.3. Description of the technological scheme…………………………………12

2.4. Material calculation of production……………………………….15

2.5. Description of the device and operating principle of the main device….20

3. Conclusions on the project……………………………………………………….22

4. Standardization………………………………………………………......24

5. List of references………………………………………………………25

6. Specification………………………………………………………………………………26

7. Appendix A………………………………………………………27

8. Appendix B………………………………………………………………………………28

Colorless volatile liquid with a specific odor, lighter than water, vapor heavier than air; poorly soluble in water, well in alcohol and other organic compounds. Technical grades of benzene contain xylene and other high-boiling fractions as impurities. Benzene is a dangerous poison. In production, poisoning is possible when emergency situations, in case of violation of the rules, as well as when working in enclosed spaces (production of rubber, varnishes, etc.).

Poisoning. In high concentrations, benzene causes short-term stimulation; then general weakness sets in, increased breathing and heart rate, decreased blood pressure. In low concentrations with prolonged exposure, benzene causes changes in nervous system, blood and , amazes . The most typical changes in the blood are a decrease in the number of leukocytes, neutropenia, a decrease in the number and decrease in the content. In the future, aplastic may develop. Sometimes there is increased sensitivity to benzene in women, especially. Frequent exposure of benzene to the skin causes dryness, redness, and cracking. Benzene is excreted from the body in exhaled air and urine in unchanged form and in the form of oxidation products.

First aid and treatment. At acute poisoning with benzene, the victim is taken out to a fresh place. If breathing stops - until spontaneous breathing is restored, oxygen or carbogen, lobelia. contraindicated. For vomiting - 40% solution intravenously, for circulatory problems - caffeine. If benzene enters the vegetable oil in order to reduce the absorption of benzene and wash the stomach (caution required - dangerous). For mild poisoning - rest. When excited - medications. For anemia - transfusion red blood cell mass, for leukopenia - , .

To prevent infection, it is administered.

Prevention. If production technology allows, replacing benzene with less toxic ones, sealing the equipment optimally. Preventing pregnant and lactating women and teenagers under 18 years from working with benzene. Periodic medical examinations of workers are carried out every six months with mandatory general analysis blood. Individual prevention - use (filter or hose with air supply).