There were no flowers at home, I wanted to buy everything, but I was sorry for the money, and yesterday they brought flowers to work for 150 rubles, so I bought them, chose 2, and my son chose the third (in the middle)! Dracaena (right) Ecology of the home Dracaena has an increased ability to humidify the air. In the room where it is present, the content of formaldehyde in the air decreases. It is also capable of absorbing and neutralizing benzene, toluene, ethylbenzene, xylene, and cyclohexanone. Energy of dracaena It is believed that dracaena is a symbol of power, prestige, and prosperity. It can cleanse the energy of the home, especially where they live...
ALL ABOUT TREATMENT WITH SODA (from classmates)
Tip 1: ALL ABOUT TREATMENT WITH SODA Areas of application 1. Prevention and treatment of cancer. 2. Treatment of alcoholism. 3. Stop smoking. 4. Treatment of all types of drug addiction and substance abuse. 5. Removal of lead, cadmium, mercury, thallium, barium, bismuth and other heavy metals from the body. 6. Removal of radioactive isotopes from the body, prevention of radioactive contamination of the body. 7. Leaching, dissolving all harmful deposits in the joints and spine; stones in the liver and kidneys, i.e. treatment of radiculitis, osteochondrosis, polyarthritis, gout, rheumatism, urolithiasis, cholelithiasis; dissolving stones in...
A) Halogenation. Electrophilic substitution reactions take place in the presence of catalysts - chlorides or bromides of aluminum or iron.
When halogenating benzene homologues, a mixture of isomers is usually obtained, because alkyl substituents are type I orientants. In general, the process is shown in the diagram:
b ) Nitration. Benzene and its homologues quite easily form nitro derivatives if not pure nitric acid is used, but the so-called nitrating mixture - concentrated HNO 3 and H 2 SO 4:
nitrobenzene
trinitrotoluene
V) Alkylation. As mentioned above, Friedel-Crafts alkylation is one of the main laboratory methods for obtaining benzene homologues:
Alkylation with alkenes is widely used in industry. The role of the catalyst in this case is played by the hydrogen ion H+. No other products except benzene homologues are formed. Alkylation with ethene (ethylene) produces ethylbenzene, and in the case of propene (propylene) produces isopropylbenzene (cumene)
2 . Catalytic hydrogenation benzene and its homologues occur at elevated pressure using catalysts (Ni, Pt). In this case, benzene is hydrogenated to cyclohexane, and, for example, methylbenzene (toluene) is hydrogenated to methylcyclohexane.
C 6 H 5 CH 3 + 3H 2 C 6 H 11 CH 3
3. Radical reactions occur during the interaction of arene vapors under harsh conditions (UV radiation or temperatures of the order of 500 o C). It should be noted that benzene and its homologues react differently.
In the case of benzene, it is realized radical accession
During radical chlorination of toluene, hydrogen atoms will be successively replaced according to the mechanism radical substitution.
4. Oxidation. Oxidation is more typical for benzene homologues. If the homologue had only one side chain, then the organic oxidation product would be benzoic acid. In this case, the length and structure of the chain do not matter. When homologues following toluene are oxidized with potassium permanganate in an acidic environment, in addition to benzoic acid, carbonic acid is formed.
Some properties of styrene.
As mentioned above, styrene does not belong to arenes, since it has a double bond, and the main type of chemical reactions for it will be addition, oxidation and polymerization reactions.
So styrene easily reacts with bromine water, discoloring it, which is a qualitative reaction to the double bond:
The hydrogenation of styrene on a nickel catalyst occurs according to the same scheme:
The oxidation of styrene is carried out with a cold aqueous solution of potassium permanganate, the oxidation product will be an aromatic dihydric alcohol:
When oxidized with a hot solution of potassium permanganate in the presence of sulfuric acid, benzoic acid and carbon dioxide will be formed.
An important reaction of great practical importance is the polymerization reaction of styrene:
The vinyl group is a type I orientant, so further catalytic substitution (for example, with haloalkanes) will go to the ortho and para positions.
7.3.Examples of problem solving
Example 21. The ozone density of a gas mixture consisting of benzene and hydrogen vapor is 0.2. After passing through a contact apparatus for the synthesis of cyclohexane, the value of this relative density was 0.25. Determine the volume fraction of cyclohexane vapor in the final mixture and the practical yield of cyclohexane.
Solution:
1) Find the molar mass of the original mixture:
M cm = D(O 3)∙M (O 3) = 0.2∙ 48 = 9.6 g/mol.
2) The molar mass of the final mixture is 0.25 ∙ 48 = 12 g/mol.
3) Find the molar ratio of the components in the original mixture
М cm = φ∙М(benzo.) + М(hydrogen) ∙(1-φ), where φ is the molar (volume) fraction of benzene
9.6 = 78φ + 2(1 –φ); 7.6 = 76φ; φ =0.1.
This means that the volume fraction of hydrogen is 0.9.
Therefore, hydrogen is in excess; we calculate using benzene.
4) Let the amount of the initial mixture be 1 mol.
Then n(C 6 H 6) = 0.1 mol, n(H 2) = 0.9 mol,
and the mass of the initial mixture is m cm = 1∙9.6 = 9.6 g.
Let us denote the amount of reacted benzene –z(mol) and
Let's draw up a quantitative balance of this reaction.
C 6 H 6 + 3 H 2 = C 6 H 12
Was 0.1 0.9 0
Reacted z 3 z z
Let's write this data for convenience in the form of a table:
5) Find the total amount of substances in the final reaction mixture:
n(con) = 0.1 – z + 0.9 – 3z + z = 1 - 3 z.
Since the total mass of substances in the contact apparatus has not changed,
then n(con) = m cm / M (final) = 9.6/12 = 0.8 mol.
6) Then 1 – 3z = 0.8; 3 z = 0.2; z= 0.067.
In this case, the volume fraction of cyclohexane is 0.067/0.8 = 0.084.
7) The theoretical amount of cyclohexane is 0.1 mol; the amount of cyclohexane formed is 0.067 mol. Practical solution
η =0.067/0.1= 0.67 (67.0%).
Answer: φ(cyclohexane) = 0.084. η =0.067/0.1= 0.67 (67.0%).
Example 22. To neutralize a mixture of aromatic acids obtained by oxidation of a mixture of ethylbenzene and its isomers, a volume of sodium hydroxide solution is required that is five times smaller than the minimum volume of the same solution required to absorb all the carbon dioxide obtained by burning the same portion of a mixture of isomers. Determine the mass fraction of ethylbenzene in the initial mixture.
Solution:
1) Ethylbenzene - C 6 H 5 C 2 H 5. M = 106 g/mol; its isomers are dimethylbenzenes, which have the same molecular formula C 6 H 4 (CH 3) 2 and the same molar mass as ethylbenzene.
Let the amount of ethylbenzene be x(mol), and the amount of the mixture of dimethylbenzenes be y(mol).
2) Let’s write the reaction equations for the oxidation of ethylbenzene and its isomers:
5C 6 H 5 C 2 H 5 + 12KMnO 4 + 18H 2 SO 4 5C 6 H 5 COOH + 5CO 2 +
5C 6 H 4 (CH 3) 2 + 12KMnO 4 + 18H 2 SO 4 5C 6 H 4 (COOH) 2 +
12MnSO 4 + 6K 2 SO 4 + 28H 2 O
Obviously, the amounts of benzoic acid and the mixture of phthalic acids are also x and y, respectively.
3) Equations for the neutralization of the resulting organic acids:
C 6 H 5 COOH + NaOH = C 6 H 5 COONa + H 2 O
C 6 H 4 (COOH) 2 + 2NaOH = C 6 H 4 (COONa) 2 + 2 H 2 O
From these equations it follows that the total amount of alkali used for
neutralization of a mixture of acids n(total) = x + 2 y
4) Let us consider the equations for the combustion of hydrocarbons, taking into account that they are all
have the molecular formula C 8 H 10.
C 6 H 5 C 2 H 5 + 10.5 O 2 8 CO 2 + 5H 2 O
C 6 H 4 (CH 3) 2 + 10.5 O 2 8 CO 2 + 5H 2 O
5) From these equations it follows that the total amount of carbon dioxide after combustion of the initial mixture of arenes is n(CO 2) = 8x + 8y
6) Since a minimum amount of alkali is required, neutralization proceeds with the formation of an acid salt:
NaOH + CO 2 = NaHCO 3
Thus, the amount of alkali to neutralize CO 2 is also equal to
8x + 8y. In this case, 8x + 8y = 5(x + 2y); y =1.5x. x =2/3y 7) Calculation of the mass fraction of ethylbenzene
ω(ethylbenzene) = m(ethylbenzene)/m(total) = 106x/(106x +106y) =
1/ (1 +1,5) = 0,4 .
Answer: ω (ethylbenzene) = 0.4 = 40%.
Example 23. A mixture of toluene and styrene was burned in excess air. When the combustion products were passed through excess limewater, 220 g of sediment was formed. Find the mass fractions of components in the original mixture if it is known that it can add
2.24 l HBr (n.s.).
Solution:
1) Only styrene reacts with hydrogen bromide in a 1:1 ratio.
C8H8 + HBr = C8H9Br
2) Amount of hydrogen bromide substance
n(HBr) = n(C8H8) = 2.24/22.4 = 0.1 mol.
3) Let us write the equation for the combustion reaction of styrene:
C 8 H 8 + 10 O 2 8 CO 2 + 4H 2 O
According to the reaction equation, the combustion of 0.1 mol of styrene produces 0.8 mol of carbon dioxide.
4) Carbon dioxide reacts with excess calcium hydroxide also in
molar ratio 1:1 with the formation of calcium carbonate precipitate:
Ca(OH) 2 + CO 2 = CaCO 3
5) The total amount of calcium carbonate is
n(CaCO 3) = m(CaCO 3)/ M(CaCO 3) = 220/100 = 2.2 mol.
This means that during the combustion of hydrocarbons, 2.2 mol of CO 2 was also formed, from
of which 0.8 mol is produced by styrene upon combustion.
Then the share of toluene is 2.2 - 0.8 = 1.4 mol CO 2.
6) Toluene combustion equation:
C 7 H 8 + 9 O 2 7CO 2 + 4H 2 O
The amount of toluene is 7 times less than the amount of carbon dioxide:
n(toluene) = 1.4/7 = 0.2 mol.
7) Mass of styrene m(wash) = n(wash)∙M(wash) = 0.1∙104 =10.4(g);
mass of toluene m(tol) = n(tol)∙M(tol) =0.2∙92 = 18.4(g).
8) The total mass of the mixture of hydrocarbons is 10.4 + 18.4 = 28.8 (g).
mass fraction of styrene: ω = 10.4/ 28.8 = 0.361;
mass fraction of toluene ω=0.639.
Answer: ω(styrene) = 0.361 = 36.1%; ω(toluene)=0.639=63.9%.
7.4. Problems and exercises for independent solution
189 . Draw graphic formulas of all arene isomers with the general formula C 9 H 12. Name these compounds.
190 . Obtain a) meta-nitrotoluene from methane, b) styrene from ethane, c) benzyl alcohol from n-heptane, using any inorganic substances and catalysts
191. Identify the following compounds: a) benzene, styrene, toluene; b) hexene, cyclohexane, toluene; c) ethylbenzene, styrene, phenol.
192. Carry out the chain of transformations:
coke HCl Cact CH 3 Cl Cl 2.
a) CaCO 3 A B C D E
1000 o 500 o FeCl 3 UV
NaOH C 2 H 4 Br 2 KOH KMnO 4
b) sodium benzoate A B C D E
rafting H + UV alcohol H 2 O
t KMnO 4 C 2 H 5 Cl Cl 2 KOH
c) n-heptane A B C D E
Cr 2 O 3 H + AlCl 3 UV H 2 O
193 . Hydrocarbon C 9 H 12 reacted with bromine when heated. As a result, a compound with the composition C 9 H 5 Br 7 was obtained. Write the structural formulas of all hydrocarbons that could give this result. Justify your answer.
194. Draw the structural formula of the closest homologue of styrene, which has cis- and trans-isomers. Indicate the types of hybridization of carbon atoms in this compound.
195. In which of the following substances do all carbon atoms have sp 2 hybridization: toluene, 1,3 butadiene, cyclohexane, ethylbenzene, styrene, benzene?
196. Get ethylbenzene from ethanol without using other organic reagents. Any inorganic substances and catalysts can be used.
197. Give the sequence of reactions by which isophthalic acid (1,3 benzenedicarboxylic acid) can be obtained from cumene.
198. a) How many isomers does arene have, the molecule of which contains 58 protons? Draw and name these isomers.
b) Does arene, whose molecule contains 50 electrons, have isomers? Justify your answer
199. During the cyclotrimerization of acetylene at 500 o C, a gas mixture with an air density of 2.24 was formed. Calculate the practical yield of benzene.
200. As a result of cyclotrimerization of acetylene at 500 o C and a pressure of 1013 kPa, after cooling, 177.27 ml of liquid with a density of 0.88 g/ml was obtained. Determine the volume of acetylene consumed under synthesis conditions if the practical yield was 60%.
201 . During catalytic dehydrocyclization, 80 g of n-heptane was released
67.2 liters of hydrogen (n.s.). Calculate the practical yield of the resulting product.
202. The hydrocarbon discolors bromine water and, when exposed to an acidified solution of KMnO 4, forms benzoic acid with the release of carbon dioxide. When treated with an excess of ammonia solution of silver oxide, the release of a white precipitate is observed. At room temperature, the original hydrocarbon is liquid, and the mass fraction of hydrogen in it is 6.9%. Identify hydrocarbon.
203. A mixture of benzene and cyclohexene with a benzene molar fraction of 80% decolorizes 200 g of a 16% solution of bromine in carbon tetrachloride. What mass of water is formed when the same mass of mixture is burned in oxygen?
204. The nitration reaction of benzene with an excess of the nitrating mixture yielded 24.6 g of nitrobenzene. What volume of benzene (density 0.88 g/ml) reacted?
205 . When one of the arenes weighing 31.8 g was nitrated, only one nitro derivative weighing 45.3 g was formed. Determine the formula of the arene and the nitration product.
206 . A mixture of benzene and cyclohexane weighing 5 g reacted with bromine (in the dark and without heating) in the presence of iron (III) bromide. The volume of hydrogen bromide released was 1.12 liters (no.). Determine the composition of the mixture in mass fractions.
207. Calculate the mass of bromobenzene that will be obtained by reacting 62.4 g of benzene with 51.61 ml of bromine with a density of 3.1 g/ml in the presence of iron(III) bromide, if the yield is 90% of theoretical.
208 . By catalytic bromination of 50 ml of toluene (density 0.867 g/ml) with a yield of 75%, a mixture of two monobromo derivatives and a gas was obtained, which was passed through 70 g of a 40% solution of butene-1 in benzene. Find the mass fractions of substances in the resulting solution.
209. As a result of bromination of 46 g of toluene in the light, a mixture of mono- and dibromo derivatives was obtained. The volume of gas released was 17.92 l (n.s.) What is the volume of 10% sodium carbonate solution
(density 1.1 g/ml) reacted with the evolved gas if the molar concentrations of the acid salt and hydrogen bromide in the resulting solution are equal.
210. The gas released during the production of bromobenzene from 44.34 ml of benzene (density 0.88 g/ml) reacted with 8.96 liters of isobutylene. The yield of bromobenzene was 80% of theoretical, and the reaction with isobutylene was carried out with 100% yield. What compounds were formed in this case? Calculate their masses.
211. What volume of a 10% sodium hydroxide solution with a density of 1.1 g/ml will be required to neutralize the gas released during the preparation of bromobenzene from 31.2 g of benzene?
212 . When 5.2 g of a certain hydrocarbon is burned in excess oxygen, 8.96 liters of carbon dioxide (n.c.) are formed. Determine the true formula of the substance if the relative density of its vapor with respect to helium is 26.
213 . A mixture of styrene and ethylcyclohexane capable of reacting with 4.48 liters of hydrogen chloride (n.o.) was burned. This produced 134.4 g of a mixture of water and carbon dioxide. Find the volume of oxygen required to burn the same portion of the mixture.
214 . The mass of the mixture of toluene and styrene is 29.23 times greater than the mass of hydrogen required for complete catalytic hydrogenation of the initial mixture. Find the quantitative ratio of the components of the mixture.
215 . A mixture of benzene, toluene and ethylbenzene weighing 13.45 g was oxidized with potassium permanganate in an acidic medium. In this case, 12.2 g of benzoic acid and 1.12 l (n.s.) of carbon dioxide were formed. Find the mass fractions of hydrocarbons in the initial mixture.
216. When burning 23.7 g of a mixture of benzene and ethylbenzene, the volume of oxygen consumed was 1.2917 times greater than the total volume of carbon dioxide. Determine the mass fractions of substances in the initial mixture, as well as the mass of the precipitate that forms when combustion products are passed through an excess solution of lime water.
217. When 26.5 g of 1,4-dimethylbenzene was oxidized with a hot neutral solution of potassium permanganate, 66.55 g of precipitate precipitated. Determine what part of the original substance is oxidized.
218. Ethylbenzene, weighing 42.4 g, was treated first with an excess of an acidified solution of potassium permanganate, and then with an even greater excess of KOH solution. Then the water was evaporated, and the dry residue was calcined. After condensation of the vapor, 26.59 ml of colorless liquid with a density of 0.88 g/ml was obtained. Determine the practical yield of the product.
219. A mixture of styrene and dimethylcyclohexane, capable of decolorizing 320 g of 5% bromine water, was burned in air. This produced 67.2 g of a mixture of water and carbon dioxide. Calculate the volume of air spent on combustion if the volume fraction of oxygen is 20%.
220. In one of the arenas, the mass fraction of neutrons is 54.717%. Identify arenes, draw and name its isomers.
221. Determine the true formula of a hydrocarbon if the mass of one molecule is 17.276. 10 -23 g, and the mass fraction of hydrogen is 7.69%.
222. The relative density of hydrocarbon vapor with respect to neon is 6. It is known that the hydrocarbon does not react with bromine water, but is oxidized with an acidified solution of potassium permanganate to terephthalic (1,4-benzenedicarboxylic) acid, and the number of carbon atoms is 75% of the number of hydrogen atoms. Identify hydrocarbon.
223. What mass of toluene will be required to obtain 113.5 g of trinitrotoluene if the product yield is 82% of theoretical?
224. What volume of benzene (density 0.88 g/ml) can be obtained from 33.6 liters of acetylene?
225. To obtain isopropylbenzene, we took 70.0 ml of 2-bromopropane with a density of 1.314 g/ml and 39 g of benzene. The volume of the resulting isopropylbenzene turned out to be 55.5 ml (density 0.862 g/ml). Calculate the yield of isopropylbenzene.
Chapter 8. ALCOHOLS
Alcohols are hydroxy derivatives of hydrocarbons in which the –OH group is not directly bonded to the carbon atoms of the aromatic ring.
Monohydric and polyhydric alcohols are distinguished by the number of hydroxyl groups.
(diatomic, triatomic and with a large number of hydroxyl groups). Based on the nature of the hydrocarbon radical, alcohols are classified into saturated, unsaturated, cyclic, and aromatic. Alcohols in which the hydroxyl group is located at the primary carbon atom are called primary, those at the secondary carbon atom are called secondary, and those at the tertiary carbon atom are called tertiary.
For example: 
butanol-1 butanol-2 2-methyl-propanol-2
(primary) (secondary) (tertiary)
allyl alcohol ethylene glycol glycerin
(unsaturated alcohol) (dihydric alcohol) (trihydric alcohol)
cyclopentanol benzyl alcohol
(cyclic alcohol) (aromatic alcohol)
8.1. Preparation of alcohols
1. Hydration of alkenes in an acidic environment:
R 1 −CH=CH−R 2 + H 2 O(H +) R 1 −CH 2 −CH(OH) −R 2
For example:
CH 2 =CH 2 + H 2 O(H +) CH 3 – CH 2 (OH)
2. Hydrolysis of alkyl halides in an acidic or alkaline environment:
CH 3 −CH 2 −CH 2 −Br +NaOH(H 2 O) CH 3 −CH 2 −CH 2 −OH +NaBr
3. Hydrolysis of esters:
a) in an acidic environment
CH 3 COOC 2 H 5 + H 2 O(H +) = CH 3 COOH + C 2 H 5 OH
b) alkaline hydrolysis (saponification)
CH 3 COOC 2 H 5 + NaOH(H 2 O) CH 3 COONa + C 2 H 5 OH
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 different methods have been developed to replace the 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. |
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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, hazardous to the 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). Gives an azeotropic mixture with water with a boiling point of 69.25 ° C, 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. |
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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 aqueous 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 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 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.
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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 the corrosive effects 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 a 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 to the upper part of the apparatus and from here flows into the settling tank. 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.
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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;
Formation of large amounts of wastewater and industrial waste under 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 various types of schemes.
GOST 2.721 – 74 Symbols and graphical symbols in diagrams.
GOST 21.108 – 78 Symbolic and graphical representation in drawings.
GOST 7.1 – 84 Rules for preparing a list of references.
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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 Nauka / Interperiodika, -2002. – 696 p.: ill.
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Introduction…………………………………………………………………………………3
2. Technological part……………………………………………………….
2.1. Theoretical basis of the adopted production method………….5
2.2. Characteristics of raw materials and 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
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Benzene is an organic chemical compound. Belongs to the class of simplest aromatic hydrocarbons. It is produced from coal tar; when processed, it produces a colorless liquid that has a peculiar sweetish odor.
Chemical formula – (C6H6,PhH)
Benzene is highly soluble in alcohol and chloroform. Excellent dissolves fats, resins, waxes, sulfur, bitumen, rubber, linoleum. When ignited, it smokes heavily and the flame is bright.
Toxic and carcinogenic. It has narcotic, hepatotoxic and hemotoxic effects.
Use in everyday life and at work
Benzene is used in the chemical, rubber, printing and pharmaceutical industries.
Used for the production of synthetic rubbers, fibers, rubber, plastics. Paints, varnishes, mastics, and solvents are made from it. It is part of motor gasoline and is an important raw material for the manufacture of various medicines.
Other products are synthesized from benzene: ethylbenzene, diethylbenzene, isopropylbenzene, nitrobenzene and aniline.
More recently, benzene was added to motor fuel, but due to stricter environmental regulations, this additive was banned. New standards allow its content in motor fuel to be up to one percent, due to its high toxicity.
Toxicologists find benzene in foods such as eggs, canned meat, fish, nuts, vegetables, and fruits. Up to 250 mcg of benzene can enter the human body with food per day.
How does poisoning occur?
Benzene poisoning occurs through the respiratory system, less commonly through ingestion and contact with intact skin. The toxicity of benzene is very high; with prolonged interaction, chronic intoxication can develop.
Acute poisonings are rare; they can be associated with accidents at work resulting from violations of safety regulations. Thus, when cleaning benzene tanks, workers may suffer lightning death.
Once in the body, benzene can cause irritation of the nervous system and profound changes in the bone marrow and blood. Short-term exposure of benzene vapors to the body does not cause changes in the nervous system.
If acute poisoning occurs, benzene and its homologues are found in the brain, liver, adrenal glands and blood. In case of chronic poisoning, it enters the bone marrow and adipose tissue. It is excreted unchanged by the lungs.
Symptoms of acute benzene poisoning:
- headache;
- drug effect syndrome;
- dizziness;
- noise in ears,
- convulsions;
- drop in blood pressure;
- low pulse;
- irritability;
- fast fatiguability;
- general weakness;
- poor sleep;
- depression;
- nausea and vomiting.
With mild or erased forms of intoxication, changes in the blood picture are barely noticeable.
If benzene poisoning is of moderate severity, in addition to the above symptoms, bleeding from the nose and gums appears. In women, the menstrual period shortens and there is heavy bleeding. Usually such phenomena are accompanied by anemia. The liver is slightly enlarged and painful.
In severe intoxication, there are frequent complaints of poor appetite, belching, and pain in the right hypochondrium. The mucous membranes and skin become very pale, and sometimes spontaneous hemorrhages occur. The liver becomes greatly enlarged and becomes painful. Acidity and digestive ability decrease.
From the cardiovascular system, myocardial ischemia, tachycardia, and vascular hypotension may begin.
The nervous system reacts differently during severe intoxication. Sometimes there are manifestations of hyperactivity, in other cases lethargy appears, and the reflexes of the lower extremities decrease
Without timely treatment, aleukemic myelosis and, less commonly, lymphatic leukemia gradually develop.
When examining bone marrow punctate, the presence of atrophic processes in the bone marrow is detected. In some cases, its complete devastation is observed.
In case of chronic poisoning, which most often develops in industrial conditions, changes appear in the composition of the blood.
If your hands often come into contact with benzene, the skin becomes dry, cracks, blisters, itching, and swelling appear on it.
First aid and treatment
The main principle of treatment and prevention of benzene poisoning is the immediate cessation of contact with it at the first symptoms of poisoning. With chronic benzene intoxication, complete recovery can occur if contact with benzene is stopped in a timely manner. If this is not done, severe intoxication will occur and, despite various methods of therapy, treatment will be ineffective.
When inhaling benzene vapors, doctors note the following clinical picture:
excitation occurs, similar to alcohol, and subsequently the patient loses consciousness and falls into a coma. The face turns pale, convulsions and characteristic muscle twitching begin. The mucous membranes are red, the pupils are dilated. The breathing rhythm is disturbed, blood pressure is reduced, and the pulse is increased. Bleeding may occur from the nose and gums.
In this case, sodium hyposulfite, sulfur and glucose preparations are used, which help speed up the process of neutralizing benzene and its oxidation products.
In case of acute intoxication, it is necessary to provide an influx of fresh air. The victim is given artificial respiration. In case of vomiting, glucose is administered intravenously; if blood circulation is impaired, caffeine injections are given.
Bloodletting, intravenous glucose infusions, and cardiac medications are performed. If the patient is too excited, bromide drugs are used.
In severe cases with pronounced anemia, drugs that stimulate erythropoiesis, vitamin B12, folic acid, iron supplements are used together with ascorbic or hydrochloric acid. They do fractional blood transfusions.
Vitamin P in combination with ascorbic acid is very effective. To prevent the development of necrotic phenomena, penicillin and glucose are administered intravenously.
For toxic hepatitis resulting from chronic benzene poisoning, lipocaine, methionine, and choline are administered.
If benzene is taken orally, the clinical picture is as follows: the patient feels an unbearable burning sensation in the mouth and behind the sternum, severe abdominal pain, accompanied by vomiting, excitement, followed by depression. Loss of consciousness, convulsions, and muscle twitching may occur. Breathing becomes rapid at first, but soon slows down. The patient's mouth smells of bitter almonds. The temperature drops sharply. The liver is enlarged, toxic hepatopathy is detected.
At very high concentrations of benzene ingested, the face turns blue and the mucous membranes acquire a cherry-red color. The person loses consciousness almost instantly, and death occurs within a few minutes. If death does not occur after severe poisoning, health is greatly undermined, and often after a long illness, death still occurs.
If poison gets inside, the stomach is washed through a tube, vaseline oil, sodium sulfate are injected inside, and sodium thiosulfate solution, cordiamine and glucose solution and ascorbic acid are injected into the vein. A caffeine solution is injected subcutaneously.
A solution of thiamine, pyridoxine hydrochloride and cyanocobalamin is injected intramuscularly. Antibiotics are prescribed to prevent infection. If there is bleeding, Vicasol is injected into the muscle.
If the poisoning is mild, rest and warmth are required.
Prevention
In production facilities where benzene is used, periodic medical examinations are required for all workers who come into contact with benzene. The examination involves a therapist, a neurologist and a gynecologist - according to indications.
It is not allowed to take on jobs that may involve contact with benzene:
- people with organic diseases of the central nervous system;
- for all diseases of the blood system and secondary anemia;
- patients with epilepsy;
- with severe neurotic conditions;
- for all types of hemorrhagic diathesis;
- for kidney and liver diseases.
It is prohibited to allow pregnant and lactating women and minors to work with benzene.
OBTAINING ETHYLBENZENE
Ethylbenzene for the production of styrene is obtained by alkylation of benzene with ethylene according to the reaction:
Along with the main reaction, a number of side reactions occur, in which more deeply alkylated benzene derivatives are formed: diethylbenzene C6H6(C2H5)2, triethylbenzene C6H6(C2H5)3, tetraethylbenzene C6H6(C2H5)4. The catalyst for the alkylation reaction is a complex compound obtained from aluminum chloride, ethyl chloride, benzene and alkylbenzenes:
The alkylation reaction proceeds according to the following scheme.
Addition of ethylene to the catalytic complex:
Exchange reaction between the catalytic complex and benzene to form ethylbenzene:
Aluminum chloride can form ternary complexes not only with one, but also with two, three, etc. ethyl radicals which, in an exchange reaction with benzene, give polyalkylbenzenes. Therefore, in addition to ethylbenzene, the reaction mixture contains diethylbenzene and other polyalkylbenzenes.
Complexes can enter into exchange reactions not only with benzene, but also with reaction products, for example with diethylbenzene, then the transalkylation process occurs according to the following scheme:
Since the transalkylation reaction occurs simultaneously with alkylation, a fraction of polyalkylbenzenes isolated from the reaction mass during rectification is also fed into the alkylator along with benzene. As a result of all these reactions, a completely definite equilibrium composition of the reaction products is established, depending only on the ratio of alkyl radicals and benzene nuclei in the reaction mixture.
Benzene is supplied in an amount corresponding to the molar ratio benzene:ethylene = (2.8-3.3):1. The reaction mass formed during the alkylation process contains on average: 45-55% unreacted benzene, 26-35% ethylbenzene, 4-10% polyalkylbenzenes.
The technological process for producing ethylbenzene consists of two main stages: alkylation of benzene with ethylene and rectification of the reaction mass.
Alkylation of benzene with ethylene
The process of alkylation of benzene with ethylene is carried out in alkylator 1 (Fig. 37) in an ethyl chloride environment at a temperature of 125--135°C 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.
Rice. 37.
1 - alkylator, 2,3 - condensers, 4 - heat exchanger, 5, 10, 17, 22 - settling tanks; 8, 9, 13, 15, 18, 21, 24 - pumps, 7, 12, 14, 20, 23 - tanks; 8, 16 -- mixers, 11, 19 -- washing columns.
I - benzene, II - ethylene; III - ethyl chloride, IV - catalyst complex; V - polyalkylbenzenes; VI - spent catalytic complex; VII - stripping and absorption of benzene, VIII - excess water; IX -- acidic blow-offs, X -- spent alkaline solution; XI -- condensate; XII - chemically contaminated water, XIII - reaction mass, XIV - polyalkylbenzenes; XV - neutral fragrances.
The alkylation reaction releases heat, the excess amount of which is removed by the recirculating catalytic complex by evaporating benzene. Benzene from the upper part of the alkylator mixed with exhaust gas is sent to condenser 2, cooled by water. Non-condensed gases from condenser 2 are directed to condenser 3, cooled by chilled water. The strippings after condenser 3 are supplied for further recovery of benzene vapors. The benzene condensate from condensers 2 and 3 is drained by gravity down the alkylator 1. From the alkylator 1, the reaction mass through the heat exchanger 4, where it is cooled with water to 40-60 ° C, is sent to the settling tank 5 for separation from the circulating catalytic complex. The settled catalytic complex from the bottom of the settling tank 5 is taken by pump 6 and returned to the alkylator 1. To maintain the activity of the catalyst, ethyl chloride is supplied to the line of the recirculating complex. In the event of a decrease in catalyst activity, the spent catalytic complex is removed for decomposition. The reaction mass from the settling tank 5 is collected in a container 7, from where, due to the pressure in the alkylation system, it enters the mixer 8 for mixing with acidic water circulating in the decomposition system: settling tank 10 - pump 9 - mixer 8. The ratio of circulating water supplied to the mixer , and the reaction mass is (l-2):1. Water is supplied to the decomposition system from collector 12 by pump 13. The reaction mass is separated from water in settling tank 10; The lower aqueous layer is sent by pump 9 to the mixer, and the upper layer - the reaction mass - flows by gravity into the washing column and for secondary washing with water supplied by pump 21 from the washing column 19. From the washing column 11, the reaction mass flows by gravity into the collection 14, from where pump 15 is pumped out for neutralization into mixer 16. ethylbenzene reaction catalyst production purification
The lower aqueous layer from the washing column 11 is drained by gravity into container 12 and pumped 13 into mixer 8. Neutralization of the reaction mass in mixer 16 is carried out with a 2-10% solution of sodium hydroxide. The ratio of the reaction mass and circulating sodium hydroxide solution is 1:1. The separation of the reaction mass from the alkali solution occurs in settling tank 17, from where the reaction mass flows by gravity into column 19 to be washed from the alkali with aqueous condensate. The bottom layer - chemically contaminated water - is drained from the column into container 20 and pumped out by pump 21 to wash the reaction mass into column 11. The reaction mass from the upper part of the column flows by gravity into the settling tank 22, then is collected into an intermediate container 23 and pumped to the warehouse.
Isolation and purification of ethylbenzene
The reaction mass obtained from the alkylation of benzene with ethylene is heated in heat exchanger 1 (Fig. 38) due to the heat of polyalkylbenzenes, in heat exchanger 2 due to the heat of steam condensate, in heat exchanger 3 due to heat exchange with rectified ethylbenzene and in heat exchanger 4 due to the heat of steam condensate and fed into column 5 to separate unreacted benzene. Benzene vapor from the top of the column is condensed in an air condenser 7 and a condenser 8 cooled by chilled water. Non-condensed gases after condenser 8 are sent to collect benzene. The condensate - return benzene - is collected in container 9, from where part of it is supplied to the column in the form of reflux, the rest is pumped through refrigerator 11 to the warehouse.
The bottom liquid of column 5 is supplied by pump 12 to column 13 to obtain rectified ethylbenzene. The column is heated with steam through an external boiler 14. Rectified ethylbenzene vapor from the top of column 13 enters the condenser-evaporator 15, where it is condensed due to the evaporation of steam condensate. Non-condensed ethylbenzene vapors are fed into condenser 16. The resulting condensates are collected in container 17, from where pump 18 returns part of them to the column in the form of reflux, and the rest is sent through heat exchanger 3 to the warehouse.
The bottom liquid of column 13, containing polyalkylbenzenes and resins, is supplied by pump 19 to column 20 to separate polyalkylbenzenes from the resin. Polyalkylbenzene vapors from the top of column 20 are supplied for condensation. The condensate flows into container 24, from where part of it is supplied to the column in the form of reflux, the rest is pumped through heat exchanger 1 to the warehouse. Polyalkylbenzene resin from the bottom of column 20 is supplied by pump 25 to a warehouse or to a copolymer production plant.
Operating mode of the columns of the ethylbenzene separation unit
