Ethylene is used in industry for production. L.I. popova, chemistry teacher (g
Answer: Ethylene is the most important representative of a number of unsaturated hydrocarbons with one double bond: the formula - 
The gas, almost odorless, is poorly soluble in water. It burns with a glowing flame in the air. Thanks to the presence
- bond ethylene easily enters into addition reactions:
(dibromoethane)
(ethyl alcohol) Due to the presence of a double bond, ethylene molecules can combine with each other, forming chains of great length (from many thousands of original molecules). This reaction is called a polymerization reaction:
Polyethylene is widely used in industry and in everyday life. It is very inactive, does not break, and is well processed. Examples: pipes, containers (barrels, boxes), insulation material, film for packaging, glass, toys and much more. Another simple unsaturated hydrocarbon is polypropylene:
During its polymerization, polypropylene is formed - a polymer. The polymer is similar in its overall properties and application to polyethylene. 
Polypropylene is more durable than polyethylene, so many parts for a variety of machines are made from it, as well as many precision parts, for example, for escalators. Approximately 40% of polypropylene is recycled into fibers.
Technical application of ethylene and the scale of its production
SAMARA 2013
Discipline test
List of sources used
1. Tax Code Russian Federation(part two) of August 5, 2000 N 117-FZ (as amended on 03.11.2010).
2. On approval of unified forms of primary accounting documentation for labor accounting and remuneration: Resolution of the State Statistics Committee of the Russian Federation of 05.01.2004 N 1.
3. Veshunova N.L., Fomina L.F. Self-study book on accounting and tax accounting - SPb .: Prospect, 2010. - 560 p.
4. Radchenko M.G. 1C: Enterprise 8.1. Practical developer's guide - SPb .: Peter, 2007. - 512 p.
5. 1C: Enterprise 8.1.Configuration and administration. - M .: Firm "1C", 2008. - 430 p.
"Theory of chemical processes of organic synthesis"
Option number 10
Is done by a student
3 courses, 2 groups ………………………… ..
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Supervisor
professor Nesterova T.N.
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Work is protected
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Grade________________
Assignment for test
"Theoretical analysis of the ethylene production process"
1. Review the literature on the technical application of ethylene and the scale of its production.
2. To review the literature on the methods of producing ethylene, methods of its separation from the contact gas and the prospects for the development of technologies.
3. Run complete theoretical analysis the selected ethylene production process:
§ Stoichiometry and material calculations.
§ Thermochemical analysis for individual transformation and for the process as a whole.
§ Qualitative and quantitative thermodynamic analysis for individual transformation and for the process as a whole.
§ Qualitative and quantitative kinetic analysis for individual transformation and for the process as a whole.
1. Literature review ………………………………………… .... 3
1.1. Technical application of ethylene and the scale of its production .. ………… ..................................... ...................... 3
2. Methods for producing ethylene, methods for isolating it from reaction mixtures and prospects for the development of technologies ………………………………………………………………………………………………………… 5
3. Full theoretical analysis of the process of producing ethylene Pyrolysis propane ... .............................................................................. 16
3.1. Stoichiometry and material calculations .. …………… ........... 16
3.2. Thermochemical analysis for individual transformation and for the process as a whole ……………………………………… 16
3.3. Complete thermodynamic analysis of ethylene production. ... 23
3.4. Complete kinetic analysis of the process… ... ……… .. ……… 32
References ………… ..... …………………………………………… 38
Ethylene(according to IUPAC: ethen) - organic chemical compound described by the formula C 2 H 4. It is the simplest alkene ( olefin). Ethylene is practically not found in nature; under normal conditions, it is a colorless combustible gas with a faint odor. Its boiling point is -103.8 ° C, and its freezing point is -169.5 ° C. In air, it burns with a slightly luminous flame. Partially soluble in water (25.6 ml in 100 ml of water at 0 ° C), ethanol (359 ml under the same conditions). It dissolves well in diethyl ether and hydrocarbons. Contains a double bond and therefore belongs to unsaturated or unsaturated hydrocarbons.
Ethylene plays an extremely important industrial role and is also a phytohormone.
Ethylene is a very important raw material for the production of a number of synthetic products, especially ethyl alcohol, ethylene oxide (ethylene oxide), ethylene glycol (antifreeze), etc. It is partially used in autogenous welding instead of acetylene.
In 1957, Italy produced 100 thousand tons of ethylene. Ethylene production in Germany before the Second World War was based on food raw materials and coal processing products. In 1943, Germany produced about 90 thousand tons of ethylene. In 1957, the Federal Republic of Germany produced 100 thousand tons of ethylene. At the same time, there was a tendency to switch to oil raw materials. Ethylene production in England, which in 1957 amounted to about 250 thousand tons, is based on the processing of crude oil. In 1957, France received 32 thousand tons of ethylene; the feedstock is coke oven gases and heavy oil products. In 1957, Japan produced about 40 thousand tons of ethylene from crude oil.
The total world production of ethylene in 2005 was 107 million tons and continues to grow by 4-6% per year. The source of industrial production of ethylene is the pyrolysis of various hydrocarbon raw materials, for example, ethane, propane, butane, contained in the associated gases of oil production; from liquid hydrocarbons - low-octane fractions of direct distillation of oil. And also the total world production of ethylene in 2008 amounted to 113 million tons and continues to grow by 2-3% per year.
Table 1. The largest Russian companies - producers of ethylene and propylene.
In the industry of heavy organic synthesis, the following processes of chemical processing of ethylene are most widespread: polymerization, oxidation, oxosynthesis, chlorination, nitration, hydration, telomerization and alkylation.
Ethylene was first obtained by the German chemist Johann Becher in 1680 by the action of vitriol oil on wine alcohol. At first, it was identified with "combustible air", i.e. with hydrogen. Later, in 1795, the Dutch chemists Deiman, Pots-van-Trustwick, Bond and Lauerenburg obtained ethylene in a similar way and described it under the name "oily gas", since they discovered the ability of ethylene to add chlorine to form an oily liquid - ethylene chloride ("Dutch oil chemists ").
In industry, various processes are used to produce ethylene: pyrolysis of light and heavy paraffinic and naphthenic hydrocarbons, hydrogenation of acetylene, and dehydration of ethyl alcohol. In addition, ethylene is obtained as a by-product during thermal processing of solid fuels, thermal and catalytic cracking of oil, etc.
2.1 Pyrolysis of saturated hydrocarbons
The main industrial method for producing ethylene is high-temperature thermal cleavage (pyrolysis) of saturated hydrocarbons.
Depending on the method of heat supply, the following processes are distinguished: a) pyrolysis in tube furnaces; b) homogeneous pyrolysis; c) autothermal pyrolysis; d) with the use of a solid coolant.
C 2 H 6 ↔C 2 H 4 + H 2 (III.1)
C 3 H 8 ↔C 2 H 4 + CH 4 (III.2b)
C 4 H 10 ↔2C 2 H 4 + H 2 (III.3b)
C 4 H 10 ↔C 2 H 4 + C 2 H 6 (III.3d)
Schematic diagrams and modes of various pyrolysis processes are shown in the table.
2.2 Catalytic hydrogenation of acetylene to ethylene
A process for the production of ethylene by hydrogenation of acetylene has been developed in the industry.
С 2 H 2 + H 2 ↔C 2 H 4 + Qп
The optimum process temperature is 180-320 °, depending on the activity of the catalyst.
The schematic diagram of the installation is shown in Fig. one
Acetylene obtained from calcium carbide (purity 98-99%) is compressed in compressor 1 to 1.5-2 atm, cooled in refrigerator 2 and purified by a solid adsorbent (alumogel) in adsorber 3 from oil vapors, since the latter is poisonous for catalyst. The hydrogen obtained from the gas separation unit (purity 96-98%) is compressed in compressor 4, cooled in refrigerator 5, dried and purified from oil vapors in adsorber 6. Preheating of hydrogen and acetylene is carried out due to the heat of reactions either in reactor 7, or in remote heat exchangers. The optimum temperature in the reactor is maintained automatically by continuous supply of cooling water to the tubular heat exchanger of the reactor.
The hydrogenation process is carried out with significant excess of hydrogen. The hydrogenation of acetylene is almost complete. Palladium supported on silica gel is used as a catalyst. The palladium content in the catalyst does not exceed
0.01 wt% The duration of continuous operation of the catalyst is about one year.
2.3 Dehydration of ethyl alcohol
To obtain relatively small amounts of ethylene (up to 3000-5000 t / year), a method for dehydration of ethyl alcohol can be used. About 15,000 tons of ethylene were obtained by this method in the USA in 1955.
The ethanol dehydration reaction can be expressed by the equation:
Activated alumina and aluminosilicon compounds are used as a catalyst. The process is carried out at 300-400 °.
The technological scheme of the dehydration unit is given earlier.
Ethyl alcohol from tank 1 by pump 2 through heat exchanger 3 is supplied to reactor 4. The required heat is supplied through the reactor wall by dowtherm or flue gases. The reaction products, consisting of ethylene, diethyl ether, ethanol and water, pass through heat exchanger 3 and condenser 5, in which water, ethanol and diethyl ether are condensed.
In column 6, the mixture is divided into gas and liquid phases; the gas phase, consisting mainly of ethylene, is directed to the consumer through the drying and cleaning systems with solid sorbents. The liquid is fed into a column 7 with a reflux condenser 8, in which it is separated into an upper product (a mixture of ethanol and diethyl ether) and a lower product (water). The upper product is fed into the reactor 4, and the lower product is fed by the pump 9 to the absorber 6. In this case, an almost complete conversion of ethanol into ethylene is achieved.
The process of producing ethylene by dehydration of ethanol under pressure has been experimentally investigated. Ethanol was fed into the pilot plant with a pump under a pressure of 33 atm through a reactor filled with activated alumina. High blood pressure due to the need to increase the temperature to 425 °. The ethylene yield reached 95% with a purity of the obtained product of 99%.
2.4 Production of ethylene from refinery gases
Gases from thermal and catalytic cracking of oils contain 2 - 2.5% ethylene. The amount of ethylene resulting from thermal cracking does not exceed 0.15% wt. for processed raw materials and catalytic cracking - 0.45%. Therefore, the gas separation plant of ethylene production usually operates on a feed that is a mixture of cracking gas and pyrolysis gases of some components of the same cracking gas (ethane, propane, propylene, and sometimes butane). The scheme for obtaining ethylene from such gases is shown below in the block diagram, b. Refinery gases pass through a purification system and are sent to compression and preliminary drying. Before compression, pyrolysis gases containing up to 30-35 vol.% Are attached to this stream. Ethylene. After compression, preliminary separation of heavy hydrocarbons and deep drying, the mixture is sent to gas separation. The target product of gas separation is ethylene, sometimes propylene and butane-butylene mixtures, and saturated hydrocarbons - ethane propane - are returned to the pyrolysis unit.
One of the main raw materials sources for ethylene production are natural gases.
A block diagram of the process for producing ethylene from natural gases is shown in diagram-A:
The people of the British Isles are known to be addicted people. Having put half of the world under their control at one time, they did not forget about the simple joys of life. About apples, for example. In the mid-late 19th century and early 20th, apple breeding reached its peak, but for the connoisseur, breeding and varieties are not the only variety. Being a connoisseur means not only crunching your favorite variety and knowing a couple of others, but also observing the development of the taste and texture of an apple in the process of its ripening and storage for each variety. We often don’t think that a fruit is a living organism with complex biochemistry and with its own hormones. Even the fruit has already been plucked from the plant. One of the simplest hormones in structure, one of the most important and therefore the most studied, is the plant maturation hormone ethylene (C 2 H 4). Ethylene is the main contributor to all fruit distribution. You pick bananas while they are still firm and easy to transport, but green, astringent and inedible raw, send them ten thousand kilometers anywhere in the world. Then either wait until, under the influence of a naturally secreted maturation hormone, they ripen, become soft and aromatic, or if you need to sell them right now, you create an artificial ethylene atmosphere.
Ethylene, in fact, is a plant hormone with a broad effect, it regulates plant growth, foliage fall, flower opening. But it is interesting for us precisely as a fruit ripening hormone.
Fruit is the only food that nature intended as food. This is the plant's way of spreading its seeds over a wide area. But only on condition that the fruit is eaten by the distributors at the moment when the seeds are ready to germinate. And the plant regulates this with the help of ripening. The biochemistry of this process is complex, but it is evident. Color change due to the breakdown of chlorophyll to colored pigments of anthocyanins and carotenoids, breakdown of tasteless polysaccharides to sweet sugars, accumulation of aromatic compounds, breakdown of cell wall pectins with observed softening of the fruit.
In a wide group of plants, these processes can occur in the fruit even after it has been plucked from the plant and the supply of nutrients has ceased. These fruits have already accumulated enough starting substances to start ripening. And this maturation is caused by the hormone ethylene. In the scientific literature, such fruits are called climacteric, these are apples, bananas, tomatoes, etc.
For another group of fruits, ripening is possible only on a branch when accessing nutrients plants. This group includes pineapples, citrus fruits. After removal, they no longer ripen.
Ethylene is an invisible gas with a very faint smell of its own, so at home the ripening processes look a little mystical - you put a banana on the shelf and wait a week for it to ripen, put it in a sealed bag and you need to wait less. This is because ethylene works on the principle of positive feedback - it is released by the fruit itself and acts as a hormone on the same fruit, bananas emit a lot of ethylene, in this they are almost champions. In case of damage, lack of water and other stresses, the release of ethylene increases. They say that this fact was known back in Ancient egypt when several fruits were cut into the branches to ripen the figs.
In terms of chemical structure, ethylene is the simplest alkene and one of the most common chemical substances generally produced in the world, competing with sulfuric acid. Of course, not for the ripening of the fruit. For example, as a polyethylene monomer.
DEFINITION
Ethylene (ethene)- the first representative of a number of alkenes - unsaturated hydrocarbons with one double bond.
Formula - C 2 H 4 (CH 2 = CH 2). Molecular weight (mass of one mol) - 28 g / mol.
The hydrocarbon radical derived from ethylene is called vinyl (-CH = CH 2). The carbon atoms in the ethylene molecule are in sp 2 -hybridization.
Ethylene chemical properties
Ethylene is characterized by reactions proceeding by the mechanism of electrophilic, addition, radical substitution, oxidation, reduction, and polymerization reactions.
Halogenation(electrophilic addition) - the interaction of ethylene with halogens, for example, with bromine, in which bromine water is discolored:
CH 2 = CH 2 + Br 2 = Br-CH 2 -CH 2 Br.
Ethylene halogenation is also possible upon heating (300C), in this case, the double bond does not break - the reaction proceeds according to the radical substitution mechanism:
CH 2 = CH 2 + Cl 2 → CH 2 = CH-Cl + HCl.
Hydrohalogenation- interaction of ethylene with hydrogen halides (HCl, HBr) with the formation of halogenated alkanes:
CH 2 = CH 2 + HCl → CH 3 -CH 2 -Cl.
Hydration- the interaction of ethylene with water in the presence of mineral acids (sulfuric, phosphoric) with the formation of a saturated monohydric alcohol - ethanol:
CH 2 = CH 2 + H 2 O → CH 3 -CH 2 -OH.
Among the reactions of electrophilic addition, the addition hypochlorous acid(1), reactions hydroxy- and alkoxymercuration(2, 3) (obtaining organomercury compounds) and hydroborating (4):
CH 2 = CH 2 + HClO → CH 2 (OH) -CH 2 -Cl (1);
CH 2 = CH 2 + (CH 3 COO) 2 Hg + H 2 O → CH 2 (OH) -CH 2 -Hg-OCOCH 3 + CH 3 COOH (2);
CH 2 = CH 2 + (CH 3 COO) 2 Hg + R-OH → R-CH 2 (OCH 3) -CH 2 -Hg-OCOCH 3 + CH 3 COOH (3);
CH 2 = CH 2 + BH 3 → CH 3 -CH 2 -BH 2 (4).
Nucleophilic addition reactions are characteristic of ethylene derivatives containing electron-withdrawing substituents. Among the reactions of nucleophilic addition, a special place is occupied by the addition reactions of hydrocyanic acid, ammonia, ethanol. For instance,
2 ON-CH = CH 2 + HCN → 2 ON-CH 2 -CH 2 -CN.
During oxidation reactions ethylene, the formation of various products is possible, and the composition is determined by the conditions of the oxidation. So, during the oxidation of ethylene in mild conditions(oxidizing agent - potassium permanganate), the π-bond breaks and the formation of a dihydric alcohol - ethylene glycol:
3CH 2 = CH 2 + 2KMnO 4 + 4H 2 O = 3CH 2 (OH) -CH 2 (OH) + 2MnO 2 + 2KOH.
At severe oxidation ethylene with a boiling solution of potassium permanganate in an acidic medium, a complete rupture of the bond (σ-bond) occurs with the formation of formic acid and carbon dioxide:
Oxidation ethylene oxygen at 200C in the presence of CuCl 2 and PdCl 2 leads to the formation of acetaldehyde:
CH 2 = CH 2 + 1 / 2O 2 = CH 3 -CH = O.
At rebuilding ethylene, ethane, a representative of the alkane class, is formed. The reduction reaction (hydrogenation reaction) of ethylene proceeds by a radical mechanism. The condition for the reaction is the presence of catalysts (Ni, Pd, Pt), as well as heating the reaction mixture:
CH 2 = CH 2 + H 2 = CH 3 -CH 3.
Ethylene enters into polymerization reaction... Polymerization is the process of formation of a high-molecular compound - a polymer - by connecting with each other using the main valences of the molecules of the initial low-molecular substance - a monomer. Ethylene polymerization occurs under the action of acids (cationic mechanism) or radicals (radical mechanism):
n CH 2 = CH 2 = - (- CH 2 -CH 2 -) n -.
Ethylene physical properties
Ethylene is a colorless gas with a faint odor, slightly soluble in water, soluble in alcohol, well soluble in diethyl ether. When mixed with air, forms an explosive mixture
Getting ethylene
The main methods for producing ethylene:
- dehydrohalogenation of halogenated alkanes under the action of alcoholic solutions of alkalis
CH 3 -CH 2 -Br + KOH → CH 2 = CH 2 + KBr + H 2 O;
- dehalogenation of dihalogenated alkane derivatives under the action of active metals
Cl-CH 2 -CH 2 -Cl + Zn → ZnCl 2 + CH 2 = CH 2;
- dehydration of ethylene by heating it with sulfuric acid (t> 150 C) or passing its vapor over the catalyst
CH 3 -CH 2 -OH → CH 2 = CH 2 + H 2 O;
- dehydrogenation of ethane upon heating (500C) in the presence of a catalyst (Ni, Pt, Pd)
CH 3 -CH 3 → CH 2 = CH 2 + H 2.
Ethylene application
Ethylene is one of the most important compounds produced on a huge industrial scale. It is used as a raw material for the production of a whole range of various organic compounds (ethanol, ethylene glycol, acetic acid, etc.). Ethylene is used as a raw material for the production of polymers (polyethylene, etc.). It is used as a substance that accelerates the growth and ripening of vegetables and fruits.
Examples of problem solving
EXAMPLE 1
| Exercise | Perform a series of transformations ethane → ethene (ethylene) → ethanol → ethene → chloroethane → butane. |
| Solution | To obtain ethene (ethylene) from ethane, it is necessary to use the ethane dehydrogenation reaction, which occurs in the presence of a catalyst (Ni, Pd, Pt) and upon heating: C 2 H 6 → C 2 H 4 + H 2. Obtaining ethanol from ethene is carried out according to the hydration reaction, flowing water in the presence of mineral acids (sulfuric, phosphoric): C 2 H 4 + H 2 O = C 2 H 5 OH. To obtain ethene from ethanol, a dehydration reaction is used: Chloroethane is obtained from ethene by the hydrohalogenation reaction: C 2 H 4 + HCl → C 2 H 5 Cl. To obtain butane from chloroethane, the Wurtz reaction is used: 2C 2 H 5 Cl + 2Na → C 4 H 10 + 2NaCl. |
EXAMPLE 2
| Exercise | Calculate how many liters and grams of ethylene can be obtained from 160 ml of ethanol, the density of which is 0.8 g / ml. |
| Solution | Ethylene can be obtained from ethanol by a dehydration reaction, the condition of which is the presence of mineral acids (sulfuric, phosphoric). Let us write the equation for the reaction of obtaining ethylene from ethanol: C 2 H 5 OH → (t, H2SO4) → C 2 H 4 + H 2 O. Let's find the mass of ethanol: m (C 2 H 5 OH) = V (C 2 H 5 OH) × ρ (C 2 H 5 OH); m (C 2 H 5 OH) = 160 × 0.8 = 128 g. Molar mass (molecular weight of one mol) of ethanol, calculated using the table chemical elements DI. Mendeleev - 46 g / mol. Let's find the amount of ethanol substance: v (C 2 H 5 OH) = m (C 2 H 5 OH) / M (C 2 H 5 OH); v (C 2 H 5 OH) = 128/46 = 2.78 mol. According to the reaction equation v (C 2 H 5 OH): v (C 2 H 4) = 1: 1, therefore, v (C 2 H 4) = v (C 2 H 5 OH) = 2.78 mol. The molar mass (molecular weight of one mol) of ethylene, calculated using the table of chemical elements of D.I. Mendeleev - 28 g / mol. Let's find the mass and volume of ethylene: m (C 2 H 4) = v (C 2 H 4) × M (C 2 H 4); V (C 2 H 4) = v (C 2 H 4) × V m; m (C 2 H 4) = 2.78 x 28 = 77.84 g; V (C 2 H 4) = 2.78 × 22.4 = 62.272 liters. |
| Answer | The mass of ethylene is 77.84 g, the volume of ethylene is 62.272 liters. |
Ethylene(other name - ethen) - a chemical compound described by the formula C 2 H 4. Ethylene is practically not found in nature. It is a colorless, low odor, combustible gas. Partially soluble in water(25.6 ml in 100 ml of water at 0 ° C), ethanol (359 ml under the same conditions). It dissolves well in diethyl ether and hydrocarbons.
Ethylene is the simplest alkene(olefin). Contains a double bond and therefore belongs to unsaturated compounds. Plays an extremely important role in the industry, and is also a phytohormone.
Raw materials for polyethylene and not only
Ethylene is the world's most produced organic compound; total world ethylene production in 2005 was 107 million tonnes and continues to grow by 4–6% per year. The source of industrial production of ethylene is the pyrolysis of various hydrocarbon raw materials, for example, ethane, propane, butane, contained in the associated gases of oil production; from liquid hydrocarbons - low-octane fractions of direct distillation of oil. The ethylene yield is about 30%. At the same time, propylene and a number of liquid products (including aromatic hydrocarbons) are formed.
When ethylene is chlorinated, 1,2-dichloroethane is obtained, hydration leads to ethyl alcohol, interaction with HCl leads to ethyl chloride. Ethylene oxidation with atmospheric oxygen in the presence of a catalyst produces ethylene oxide. In liquid-phase catalytic oxidation with oxygen, acetaldehyde is obtained, under the same conditions in the presence of acetic acid - vinyl acetate. Ethylene is an alkylating agent, for example, under Friedel-Crafts reaction conditions, it is capable of alkylating benzene and other aromatic compounds. Ethylene is capable of polymerizing in the presence of catalysts both independently and acting as a comonomer, forming a wide range of polymers with different properties.
Application
Ethylene is one of the basic products of industrial chemistry and is at the base of a number of synthesis chains. The main use of ethylene is as a monomer in the production of polyethylene(the largest polymer in the world production). Depending on the polymerization conditions, low-pressure polyethylene and high-pressure polyethylene are obtained.
Also, polyethylene is used for production of a range of copolymers, including propylene, styrene, vinyl acetate and others. Ethylene is a raw material for the production of ethylene oxide; as an alkylating agent in the production of ethylbenzene, diethylbenzene, triethylbenzene.
Ethylene is used as a starting material for production of acetaldehyde and synthetic ethyl alcohol... It is also used for the synthesis of ethyl acetate, styrene, vinyl acetate, vinyl chloride; in the production of 1,2-dichloroethane, ethyl chloride.
Ethylene is used for acceleration of fruit ripening- for example, tomatoes, melons, oranges, tangerines, lemons, bananas; defoliation of plants, reduction of pre-harvest abscission of fruits, to reduce the strength of attachment of fruits to mother plants, which facilitates mechanized harvesting.
Ethylene has high concentrations on humans and animals narcotic effect.
