Natural sources of hydrocarbons. Natural sources of hydrocarbons – Knowledge Hypermarket

Lesson objectives:

Educational:

Develop students' cognitive activity.
To familiarize students with natural sources of hydrocarbons: oil, natural gas, coal, their composition and processing methods.
To study the main deposits of these resources globally and in Russia.
Show their significance in the national economy.
Consider protection issues environment.

Educational:

Cultivating interest in studying the topic, instilling speech culture in chemistry lessons.

Educational:

Develop attention, observation, listening skills and drawing conclusions.

Pedagogical methods and techniques:

Perceptual approach.
Gnostic approach.
Cybernetic approach.

Equipment: Interactive whiteboard, multimedia, electronic textbooks MarSTU, Internet, collections “Oil and the main products of its processing”, “Coal and the most important products of its processing”.

Lesson progress

I. Organizational moment.

I introduce the purpose and objectives of this lesson.

II. Main part.

The most important natural sources of hydrocarbons are: oil, coal, natural and associated petroleum gases.

Oil – “black gold” (I introduce students to the origin of oil, main reserves, production, composition of oil, physical properties, petroleum products).

During the rectification process, oil is divided into the following fractions:

I am showing samples of fractions from the collection (demonstration accompanied by explanation).

Distillation gases– a mixture of low-molecular hydrocarbons, mainly propane and butane, with a boiling temperature of up to 40 ° C,
Gasoline fraction (gasoline)– HC composition C 5 H 12 to C 11 H 24 (boiling point 40-200°C, with a finer separation of this fraction one gets gas oil(petroleum ether, 40 - 70°C) and petrol(70 - 120°C),
Naphtha fraction– HC composition from C 8 H 18 to C 14 H 30 (boil temperature 150 - 250°C),
Kerosene fraction– HC composition from C 12 H 26 to C 18 H 38 (boil temperature 180 - 300°C),
Diesel fuel– HC composition from C 13 H 28 to C 19 H 36 (boil temperature 200 - 350°C)

Residue from oil refining – fuel oil– contains hydrocarbons with the number of carbon atoms from 18 to 50. Distillation under reduced pressure from fuel oil produces solar oil(C 18 H 28 – C 25 H 52), lubricating oils(C 28 H 58 – C 38 H 78), petrolatum And paraffin– low-melting mixtures of solid hydrocarbons. Solid residue from fuel oil distillation – tar and products of its processing - bitumen And asphalt used for making road surfaces.

The products obtained as a result of oil rectification are subjected to chemical processing. One of them is cracking.

Cracking is the thermal decomposition of petroleum products, which leads to the formation of hydrocarbons with fewer carbon atoms in the molecule. (I use the MarSTU electronic textbook, which talks about the types of cracking).

Students compare thermal and catalytic cracking. (Slide No. 16)

Thermal cracking.

The breakdown of hydrocarbon molecules occurs at a higher temperature (470-5500 C). The process proceeds slowly, hydrocarbons with an unbranched chain of carbon atoms are formed. Gasoline obtained as a result of thermal cracking, along with saturated hydrocarbons, contains many unsaturated hydrocarbons. Therefore, this gasoline has greater detonation resistance than straight distilled gasoline. Thermally cracked gasoline contains many unsaturated hydrocarbons, which easily oxidize and polymerize. Therefore, this gasoline is less stable during storage. When it burns, various parts of the engine can become clogged.

Catalytic cracking.

The splitting of hydrocarbon molecules occurs in the presence of catalysts and at a lower temperature (450-5000 C). The main focus is on gasoline. They are trying to get more of it and always of better quality. Catalytic cracking appeared precisely as a result of the long-term, persistent struggle of oil workers to improve the quality of gasoline. Compared to thermal cracking, the process proceeds much faster, and not only the splitting of hydrocarbon molecules occurs, but also their isomerization, i.e. hydrocarbons with a branched chain of carbon atoms are formed. Catalytic cracked gasoline is even more resistant to detonation than thermally cracked gasoline.

Coal. (I introduce students to the origins coal, main reserves, production, physical properties, processed products).

Origin: (I use the electronic textbook of MarSTU, where they talk about the origin of coal).

Main reserves: (slide number 18) On the map I show students the largest coal deposits in Russia in terms of production volume - these are the Tunguska, Kuznetsk, and Pechora basins.

Production:(I use the electronic textbook of MarSTU, where they talk about coal mining).

Coke gas– which includes H 2, CH 4, CO, CO 2, impurities of NH 3, N 2 and other gases,
Coal tar– contains several hundred different organic substances, including benzene and its homologues, phenol and aromatic alcohols, naphthalene and various heterocyclic compounds,
Nadsmolnaya, or ammonia water– contains dissolved ammonia, as well as phenol, hydrogen sulfide and other substances,
Coke– solid coking residue, almost pure carbon.

Natural and petroleum associated gases. (I introduce students to the main reserves, production, composition, processed products).

III. Generalization.

In the summary part of the lesson, I created a test using the Turning Point program. The students armed themselves with remote controls. When a question appears on the screen, by pressing the appropriate button, they select the correct answer.

1. Main components natural gas are:

Ethane;
Propane;
Methane;
Butane.

2. Which fraction of petroleum distillation contains from 4 to 9 carbon atoms per molecule?

Naphtha;
Gas oil;
Petrol;
Kerosene.

3. What is the purpose of cracking heavy petroleum products?

Methane production;
Obtaining gasoline fractions with high detonation resistance;
Synthesis gas production;
Hydrogen production.

4. Which process is not related to oil refining?

Coking;
Fractional distillation;
Catalytic cracking;
Thermal cracking.

5. Which of the following events is the most dangerous for aquatic ecosystems?

Violation of oil pipeline tightness;
Oil spill as a result of a tanker accident;
Violation of technology during deep oil production on land;
Transportation of coal by sea.

6. From methane, which forms natural gas, we obtain:

Synthesis gas;
Ethylene;
Acetylene;
Butadiene.

7. What features distinguish catalytic cracking gasoline from straight distilled gasoline?

Presence of alkenes;
Presence of alkynes;
The presence of hydrocarbons with a branched chain of carbon atoms;
High detonation resistance.

The test result is immediately visible on the screen.

Homework:§ 10, ex.1 – 8

Literature:

L.Yu. Alikberova “ Entertaining chemistry“. – M.: “AST-Press”, 1999.
O.S. Gabrielyan, I.G. Ostroumov “Handbook for chemistry teachers, grade 10.” – M.: “Blik and K,” 2001.
O.S. Gabrielyan, F.N. Maskaev, S.Yu. Ponomarev, V.I. Terenin “Chemistry 10th grade.” – M.: “Drofa”, 2003.

Message on the topic: " Natural springs hydrocarbons"

Prepared

Hydrocarbons

Hydrocarbons are compounds consisting only of carbon and hydrogen atoms.

Hydrocarbons are divided into cyclic (carbocyclic compounds) and acyclic.

Cyclic (carbocyclic) are compounds that contain one or more rings consisting only of carbon atoms (in contrast to heterocyclic compounds containing heteroatoms - nitrogen, sulfur, oxygen, etc.).

d.). Carbocyclic compounds, in turn, are divided into aromatic and non-aromatic (alicyclic) compounds.

Acyclic hydrocarbons include organic compounds whose carbon skeleton molecules are open chains.

These chains can be formed by single bonds (alkanes СnН2n+2), contain one double bond (alkenes СnН2n), two or more double bonds (dienes or polyenes), one triple bond (alkynes СnН2n-2).

As you know, carbon chains are part of most organic matter. Thus, the study of hydrocarbons acquires special meaning, since these compounds are the structural basis of other classes organic compounds.

In addition, hydrocarbons, especially alkanes, are the main natural sources of organic compounds and the basis of the most important industrial and laboratory syntheses.

Hydrocarbons are the most important raw materials for chemical industry. In turn, hydrocarbons are quite widespread in nature and can be isolated from various natural sources: oil, associated petroleum and natural gas, coal.

Let's take a closer look at them.

Oil is a natural complex mixture of hydrocarbons, mainly linear and branched alkanes, containing from 5 to 50 carbon atoms in molecules, with other organic substances.

Its composition significantly depends on the place of its extraction (deposit); in addition to alkanes, it may contain cycloalkanes and aromatic hydrocarbons.

The gaseous and solid components of oil are dissolved in its liquid components, which determines its physical state. Oil is an oily liquid of a dark (brown to black) color with a characteristic odor, insoluble in water. Its density is less than that of water, therefore, when oil gets into it, it spreads over the surface, preventing the dissolution of oxygen and other air gases in the water.

It is obvious that, when oil enters natural bodies of water, it causes the death of microorganisms and animals, leading to environmental disasters and even catastrophes. There are bacteria that can use oil components as food, converting it into harmless products of their vital activity. It is clear that the use of cultures of these bacteria is the most environmentally friendly and promising way to combat environmental pollution with oil during its production, transportation and refining.

In nature, oil and associated petroleum gas, which will be discussed below, fill the cavities of the earth's interior. Representing a mixture various substances, oil does not have a constant boiling point. It is clear that each of its components retains its individual characteristics in the mixture. physical properties, which makes it possible to separate oil into its components. To do this, it is purified from mechanical impurities and sulfur-containing compounds and subjected to so-called fractional distillation, or rectification.

Fractional distillation - physical method separating a mixture of components from different temperatures boiling.

During the rectification process, oil is divided into the following fractions:

Rectifying gases are a mixture of low molecular weight hydrocarbons, mainly propane and butane, with a boiling point of up to 40 ° C;

Gasoline fraction (gasoline) - hydrocarbons of composition from C5H12 to C11H24 (boiling point 40-200 ° C); with a finer separation of this fraction, gasoline (petroleum ether, 40-70 °C) and gasoline (70-120 °C) are obtained;

Naphtha fraction - hydrocarbons of composition from C8H18 to C14H30 (boiling point 150-250 °C);

Kerosene fraction - hydrocarbons of composition from C12H26 to C18H38 (boiling point 180-300 °C);

Diesel fuel - hydrocarbons of composition from C13H28 to C19H36 (boiling point 200-350 ° C).

The residue from oil distillation - fuel oil - contains hydrocarbons with the number of carbon atoms from 18 to 50. By distillation under reduced pressure, diesel oil (C18H28-C25H52), lubricating oils (C28H58-C38H78), petroleum jelly and paraffin are obtained from fuel oil - low-melting mixtures of solid hydrocarbons.

The solid residue from the distillation of fuel oil - tar and the products of its processing - bitumen and asphalt are used for the manufacture of road surfaces.

Associated petroleum gas

Oil fields contain, as a rule, large accumulations of so-called associated oil gas, which gathers over oil in earth's crust and partially dissolves in it under the pressure of overlying rocks.

Like oil, associated petroleum gas is a valuable natural source of hydrocarbons. It contains mainly alkanes, whose molecules contain from 1 to 6 carbon atoms. It is obvious that the composition of associated petroleum gas is much poorer than oil. However, despite this, it is also widely used both as a fuel and as a raw material for the chemical industry. Just a few decades ago, in most oil fields, associated petroleum gas was burned as a useless supplement to oil.

Currently, for example, in Surgut, the richest oil reserve in Russia, the cheapest electricity in the world is generated using associated petroleum gas as fuel.

Associated petroleum gas, compared to natural gas, is richer in composition in various hydrocarbons. Dividing them into fractions, we get:

Gas gasoline is a highly volatile mixture consisting mainly of lenthane and hexane;

A propane-butane mixture, consisting, as the name implies, of propane and butane and easily turning into a liquid state when the pressure increases;

Dry gas is a mixture containing mainly methane and ethane.

Gas gasoline, being a mixture of volatile components with a small molecular weight, evaporates well even at low temperatures. This allows the use of gas gasoline as fuel for engines internal combustion in the Far North and as an addition to motor fuel, making it easier to start engines in winter conditions.

The propane-butane mixture in the form of liquefied gas is used as household fuel (the familiar gas cylinders at the dacha) and for filling lighters.

The gradual transition of road transport to liquefied gas is one of the main ways to overcome the global fuel crisis and solve environmental problems.

Dry gas, close in composition to natural gas, is also widely used as fuel.

However, the use of associated petroleum gas and its components as fuel is far from the most promising way to use it.

It is much more efficient to use associated petroleum gas components as raw materials for chemical production. Hydrogen, acetylene, unsaturated and aromatic hydrocarbons and their derivatives are obtained from alkanes that make up associated petroleum gas.

Gaseous hydrocarbons can not only accompany oil in the earth's crust, but also form independent accumulations - natural gas deposits.

Natural gas

Natural gas is a mixture of gaseous saturated hydrocarbons with a low molecular weight. The main component of natural gas is methane, the share of which, depending on the field, ranges from 75 to 99% by volume.

In addition to methane, natural gas includes ethane, propane, butane and isobutane, as well as nitrogen and carbon dioxide.

Like associated petroleum, natural gas is used both as a fuel and as a raw material for the production of a variety of organic and inorganic substances.

You already know that from methane, the main component of natural gas, hydrogen, acetylene and methyl alcohol, formaldehyde and formic acid, many other organic substances. Natural gas is used as fuel in power plants, in boiler systems for water heating of residential and industrial buildings, in blast furnace and open-hearth industries.

By striking a match and lighting the gas in the kitchen gas stove of a city house, you “trigger” a chain reaction of oxidation of alkanes that make up natural gas.

Coal

In addition to oil, natural and associated petroleum gases, coal is a natural source of hydrocarbons.

0n forms thick layers in the bowels of the earth, its proven reserves significantly exceed oil reserves. Like oil, coal contains large number various organic substances.

In addition to organic, it also contains inorganic substances, such as water, ammonia, hydrogen sulfide and, of course, carbon itself - coal. One of the main methods of processing coal is coking - calcination without air access. As a result of coking, which is carried out at a temperature of about 1000 °C, the following are formed:

Coke oven gas, which contains hydrogen, methane, carbon dioxide and carbon dioxide, admixtures of ammonia, nitrogen and other gases;
coal tar containing several hundred times-personal organic substances, including benzene and its homologues, phenol and aromatic alcohols, naphthalene and various heterocyclic compounds;
suprasin, or ammonia water, containing, as the name implies, dissolved ammonia, as well as phenol, hydrogen sulfide and other substances;
coke is a solid residue from coking, almost pure carbon.

Coke is used in the production of iron and steel, ammonia is used in the production of nitrogen and combined fertilizers, and the importance of organic coking products can hardly be overestimated.

Conclusion: thus, oil, associated petroleum and natural gases, coal are not only the most valuable sources of hydrocarbons, but also part of a unique storehouse of irreplaceable natural resources, the careful and reasonable use of which - necessary condition progressive development of human society.

Natural sources of hydrocarbons are fossil fuels. Most organic substances are obtained from natural sources. In the process of synthesis of organic compounds, natural and accompanying gases, coal and brown coal, oil, oil shale, peat, and products of animal and plant origin are used as raw materials.

What is the composition of natural gas

The qualitative composition of natural gas consists of two groups of components: organic and inorganic.

Organic components include: methane - CH4; propane - C3H8; butane - C4H10; ethane - C2H4; heavier hydrocarbons with more than five carbon atoms. Inorganic components include following connections: hydrogen (in small quantities) - H2; carbon dioxide - CO2; helium - He; nitrogen - N2; hydrogen sulfide - H2S.

What exactly the composition of a particular mixture will be depends on the source, that is, the deposit. The same reasons explain the various physical and chemical properties natural gas.

Chemical composition
The main part of natural gas is methane (CH4) - up to 98%. Natural gas may also contain heavier hydrocarbons:
* ethane (C2H6),
* propane (C3H8),
* butane (C4H10)
- methane homologues, as well as other non-hydrocarbon substances:
* hydrogen (H2),
* hydrogen sulfide (H2S),
* carbon dioxide (CO2),
* nitrogen (N2),
* helium (He).

Natural gas is colorless and odorless.

To identify a leak by smell, a small amount of mercaptans, which have a strong unpleasant odor, is added to the gas.

What are the advantages of natural gas over other types of fuel?

1. simplified extraction (does not require artificial pumping)

2. ready for use without intermediate processing (distillation)

transportation in both gaseous and liquid states.

4. minimal emissions harmful substances upon combustion.

5. convenience of supplying fuel in an already gaseous state during its combustion (lower cost of equipment using this type fuel)

reserves are more extensive than other fuels (lower market value)

7. Use in large industries national economy than other types of fuel.

a sufficient amount in the depths of Russia.

9. Emissions of the fuel itself during accidents are less toxic to the environment.

10. high combustion temperature for use in technological schemes of the national economy, etc., etc.

Application in the chemical industry

It is used to produce plastics, alcohol, rubber, and organic acids. Only with the use of natural gas can one synthesize chemicals that simply cannot be found in nature, for example, polyethylene.

methane is used as a raw material for the production of acetylene, ammonia, methanol and hydrogen cyanide. At the same time, natural gas is the main raw material base for the production of ammonia. Almost three quarters of all ammonia is used to produce nitrogen fertilizers.

Hydrogen cyanide, obtained from ammonia, together with acetylene serves as the initial raw material for the production of various synthetic fibers. Acetylene can be used to produce various sheet metals, which are widely used in industry and everyday life.

It is also used to produce acetate silk.

Natural gas is one of the best views fuels that are used for industrial and domestic needs. Its value as a fuel also lies in the fact that this mineral fuel is quite environmentally friendly. When it burns, much less harmful substances appear when compared with other types of fuel.

The most important petroleum products

During the refining process, petroleum is used to produce fuel (liquid and gaseous), lubricating oils and greases, solvents, individual hydrocarbons - ethylene, propylene, methane, acetylene, benzene, toluene, xylo, etc., solid and semi-solid mixtures of hydrocarbons (paraffin, petroleum jelly , ceresin), petroleum bitumen, carbon black (soot), petroleum acids and their derivatives.

Liquid fuel obtained from oil refining is divided into motor fuel and boiler fuel.

Gaseous fuels include hydrocarbon liquefied fuel gases used for municipal services. These are mixtures of propane and butane in different ratios.

Lubricating oils designed to provide liquid lubrication in various machines and mechanisms are divided depending on the application into industrial, turbine, compressor, transmission, insulating, and motor oils.

Greases are petroleum oils thickened with soaps, solid hydrocarbons and other thickeners.

Individual hydrocarbons obtained from the processing of oil and petroleum gases serve as raw materials for the production of polymers and organic synthesis products.

Of these, the most important are the limiting ones - methane, ethane, propane, butane; unsaturated – ethylene, propylene; aromatic - benzene, toluene, xylenes. Also products of petroleum refining are saturated hydrocarbons with a high molecular weight (C16 and higher) - paraffins, ceresins, used in the perfume industry and as thickeners for greases.

Petroleum bitumen, obtained from heavy oil residues by oxidation, is used for road construction, for the production of roofing materials, for the preparation of asphalt varnishes and printing inks, etc.

One of the main products of oil refining is motor fuel, which includes aviation and motor gasoline.

What are the main natural sources of hydrocarbons that you know?

Natural sources of hydrocarbons are fossil fuels.

Most organic substances are obtained from natural sources. In the process of synthesis of organic compounds, natural and accompanying gases, coal and brown coal, oil, oil shale, peat, and products of animal and plant origin are used as raw materials.

12Next ⇒

Answers to paragraph 19

1. What are the main natural sources of hydrocarbons that you know?
Oil, natural gas, shale, coal.

What is the composition of natural gas? Point to geographical map the most important deposits: a) natural gas; b) oil; c) coal.

3. What advantages does natural gas have over other types of fuel? For what purposes is natural gas used in the chemical industry?
Natural gas, compared to other sources of hydrocarbons, is the easiest to produce, transport and process.

In the chemical industry, natural gas is used as a source of low molecular weight hydrocarbons.

4. Write the reaction equations for the production of: a) acetylene from methane; b) chloroprene rubber from acetylene; c) carbon tetrachloride from methane.

5. How do associated petroleum gases differ from natural gas?
Associated gases are volatile hydrocarbons dissolved in oil.

Their isolation occurs by distillation. Unlike natural gas, it can be isolated at any stage of oil field development.

6. Describe the main products obtained from associated petroleum gases.
Main products: methane, ethane, propane, n-butane, pentane, isobutane, isopentane, n-hexane, n-heptane, hexane and heptane isomers.

Name the most important petroleum products, indicate their composition and areas of their application.

8. What lubricating oils are used in production?
Motor oils, transmission, industrial, lubricating and cooling emulsions for metal-cutting machines, etc.

How is oil distilled?

10. What is petroleum cracking? Write an equation for the reactions of hydrocarbon splitting And in this process.

Why is it possible to obtain no more than 20% of gasoline during direct distillation of oil?
Because the content of gasoline fraction in oil is limited.

12. How does thermal cracking differ from catalytic cracking? Give characteristics of thermal and catalytic cracking gasolines.
During thermal cracking, it is necessary to heat the reactants to high temperatures, with catalytic - the introduction of a catalyst reduces the activation energy of the reaction, which makes it possible to significantly reduce the reaction temperature.

How can you practically distinguish cracked gasoline from straight distilled gasoline?
Cracking gasoline has a higher octane number compared to straight distilled gasoline, i.e. is more detonation resistant and is recommended for use in internal combustion engines.

14. What is oil aromatization? Write reaction equations that explain this process.

What are the main products obtained from coking coal?
Naphthalene, anthracene, phenanthrene, phenols and coal oils.

16. How is coke obtained and where is it used?
Coke is a solid porous product gray, obtained by coconut coal at temperatures of 950-1100 without access to oxygen.

It is used for smelting cast iron, as a smokeless fuel, a reducing agent iron ore, disintegrant for batch materials.

17. What are the main products obtained:
a) from coal tar; b) from tar water; c) from coke oven gas? Where are they used? What organic substances can be obtained from coke oven gas?
a) benzene, toluene, naphthalene – chemical industry
b) ammonia, phenols, organic acids – chemical industry
c) hydrogen, methane, ethylene - fuel.

Remember all the main ways to get aromatic hydrocarbons. What are the differences between the methods for producing aromatic hydrocarbons from the products of coking coal and oil? Write the equations for the corresponding reactions.
They differ in the methods of production: primary oil refining is based on the difference in the physical properties of various fractions, and coking is based purely on chemical properties coal.

Explain how, in the process of solving energy problems in the country, the ways of processing and using natural hydrocarbon resources will be improved.
Search for new energy sources, optimization of oil production and refining processes, development of new catalysts to reduce the cost of entire production, etc.

20. What are the prospects for receiving liquid fuel from coal?
In the future, producing liquid fuel from coal is possible, provided that the costs of its production are reduced.

Task 1.

It is known that the gas contains volume fractions 0.9 methane, 0.05 ethane, 0.03 propane, 0.02 nitrogen. What volume of air will be required to burn 1 m3 of this gas under normal conditions?

Task 2.

What volume of air (no.s.) is needed to burn 1 kg of heptane?

Task 3. Calculate what volume (in l) and what mass (in kg) of carbon monoxide (IV) will be obtained upon combustion of 5 mol of octane (no.).

The main sources of hydrocarbons on our planet are natural gas, oil And coal. The most stable of hydrocarbons, saturated and aromatic, have survived millions of years of preservation in the bowels of the earth.

Natural gas consists mainly of methane with admixtures of other gaseous alkanes, nitrogen, carbon dioxide and some other gases; coal contains mainly polycyclic aromatic hydrocarbons.

Oil, unlike natural gas and coal, contains a whole range of components:

Other substances are also present in oil: heteroatomic organic compounds (contain sulfur, nitrogen, oxygen and other elements), water with salts dissolved in it, solid particles of other rocks and other impurities.

Interesting to know! Hydrocarbons are also found in space, including on other planets.

For example, methane makes up a significant part of Uranus's atmosphere and is responsible for its light turquoise color observed through a telescope. Atmosphere of Titan largest satellite Saturn, consists mainly of nitrogen, but also contains hydrocarbons methane, ethane, propane, ethyne, propyne, butadiine and their derivatives; sometimes methane rains there, and hydrocarbon rivers flow into hydrocarbon lakes on the surface of Titan.

The presence of unsaturated hydrocarbons, along with saturated and molecular hydrogen, is due to the effects of solar radiation.

Mendeleev owns the phrase: “Burning oil is the same as heating a furnace with banknotes.” Thanks to the emergence and development of oil refining technologies, in the 20th century it turned from a common fuel into the most valuable source of raw materials for the chemical industry.

Petroleum products are currently used in almost all industries.

Primary oil refining is preparation, that is, purification of oil from inorganic impurities and petroleum gas dissolved in it, and distillation, that is, physical division into factions depending on the boiling point:

From the fuel oil remaining after oil distillation at atmospheric pressure, under the influence of vacuum, components of high molecular weight are isolated, suitable for processing into mineral oils, motor fuels and other products, and the remainder - tar- used for the production of bitumen.

In progress recycling oil, individual fractions are subjected to chemical transformations.

These are cracking, reforming, isomerization and many other processes that make it possible to obtain unsaturated and aromatic hydrocarbons, branched alkanes and other valuable petroleum products. Some of them are spent on the production of high-quality fuel and various solvents, and some are raw materials for the production of new organic compounds and materials for a wide variety of industries.

But it should be remembered that hydrocarbon reserves in nature are replenished much more slowly than humanity consumes them, and the process of refining and burning petroleum products itself introduces strong deviations into the chemical balance of nature.

Of course, sooner or later nature will restore balance, but this can result in serious problems for humans. Therefore it is necessary new technologies to eliminate the use of hydrocarbons as fuel in the future.

To solve such global problems it is necessary development of fundamental science and a deep understanding of the world around us.

Compounds consisting only of carbon and hydrogen atoms.

Hydrocarbons are divided into cyclic (carbocyclic compounds) and acyclic.

Cyclic (carbocyclic) are compounds that contain one or more cycles consisting only of carbon atoms (in contrast to heterocyclic compounds containing heteroatoms - nitrogen, sulfur, oxygen, etc.). Carbocyclic compounds, in turn, are divided into aromatic and non-aromatic (alicyclic) compounds.

Acyclic hydrocarbons include organic compounds whose carbon skeleton molecules are open chains.

These chains can be formed by single bonds (alkanes), contain one double bond (alkenes), two or more double bonds (dienes or polyenes), or one triple bond (alkynes).

As you know, carbon chains are part of most organic matter. Thus, the study of hydrocarbons is of particular importance, since these compounds are the structural basis of other classes of organic compounds.

In addition, hydrocarbons, especially alkanes, are the main natural sources of organic compounds and the basis of the most important industrial and laboratory syntheses (Scheme 1).

You already know that hydrocarbons are the most important type of raw material for the chemical industry. In turn, hydrocarbons are quite widespread in nature and can be isolated from various natural sources: oil, associated petroleum and natural gas, coal. Let's take a closer look at them.

Oil- a natural complex mixture of hydrocarbons, mainly alkanes of linear and branched structure, containing from 5 to 50 carbon atoms in molecules, with other organic substances. Its composition significantly depends on the place of its extraction (deposit); in addition to alkanes, it may contain cycloalkanes and aromatic hydrocarbons.

Gaseous and solid components of oil are dissolved in its liquid components, which determines its state of aggregation. Oil is an oily liquid of a dark (brown to black) color with a characteristic odor, insoluble in water. Its density is less than that of water, therefore, when oil gets into it, it spreads over the surface, preventing the dissolution of oxygen and other air gases in the water. It is obvious that, when oil enters natural bodies of water, it causes the death of microorganisms and animals, leading to environmental disasters and even catastrophes. There are bacteria that can use oil components as food, converting it into harmless products of their vital activity. It is clear that the use of cultures of these bacteria is the most environmentally friendly and promising way to combat environmental pollution with oil during its production, transportation and refining.

In nature, oil and associated petroleum gas, which will be discussed below, fill the cavities of the earth's interior. Being a mixture of various substances, oil does not have a constant boiling point. It is clear that each of its components retains its individual physical properties in the mixture, which makes it possible to separate the oil into its components. To do this, it is purified from mechanical impurities and sulfur-containing compounds and subjected to so-called fractional distillation, or rectification.

Fractional distillation is a physical method of separating a mixture of components with different boiling points.

Distillation is carried out in special installations - distillation columns, in which cycles of condensation and evaporation of liquid substances contained in oil are repeated (Fig. 9).

The vapors formed when a mixture of substances boils are enriched with a lower-boiling (i.e., lower-temperature) component. These vapors are collected, condensed (cooled to below boiling point) and brought back to a boil. In this case, vapors are formed that are even more enriched with a low-boiling substance. By repeating these cycles many times, it is possible to achieve almost complete separation of the substances contained in the mixture.

The distillation column receives oil heated in a tube furnace to a temperature of 320-350 °C. The distillation column has horizontal partitions with holes - the so-called trays, on which condensation of oil fractions occurs. Low-boiling fractions accumulate on the higher ones, and high-boiling ones - on the lower ones.

During the rectification process, oil is divided into the following fractions:

Rectifying gases are a mixture of low molecular weight hydrocarbons, mainly propane and butane, with a boiling point of up to 40 ° C;

Gasoline fraction (gasoline) - hydrocarbons of composition from C 5 H 12 to C 11 H 24 (boiling point 40-200 ° C); with a finer separation of this fraction, gasoline (petroleum ether, 40-70 °C) and gasoline (70-120 °C) are obtained;

Naphtha fraction - hydrocarbons of composition from C8H18 to C14H30 (boiling point 150-250 °C);

Kerosene fraction - hydrocarbons of composition from C12H26 to C18H38 (boiling point 180-300 °C);

Diesel fuel - hydrocarbons of composition from C13H28 to C19H36 (boiling point 200-350 ° C).

The remainder of oil distillation is fuel oil- contains hydrocarbons with the number of carbon atoms from 18 to 50. By distillation under reduced pressure from fuel oil, diesel oil (C18H28-C25H52), lubricating oils (C28H58-C38H78), petroleum jelly and paraffin are obtained - low-melting mixtures of solid hydrocarbons. The solid residue from the distillation of fuel oil - tar and the products of its processing - bitumen and asphalt are used for the manufacture of road surfaces.

The products obtained as a result of oil rectification are subjected to chemical processing, which includes a number of complex processes. One of them is cracking of petroleum products. You already know that fuel oil is separated into components under reduced pressure. This is explained by the fact that at atmospheric pressure its components begin to decompose before reaching the boiling point. This is precisely the basis of cracking.

Cracking - thermal decomposition of petroleum products, leading to the formation of hydrocarbons with a smaller number of carbon atoms in the molecule.

There are several types of cracking: thermal, catalytic cracking, high-pressure cracking, and reduction cracking.

Thermal cracking involves the splitting of hydrocarbon molecules with a long carbon chain into shorter ones under the influence of high temperature (470-550 ° C). During this cleavage, alkenes are formed along with alkanes.

IN general view this reaction can be written as follows:

C n H 2n+2 -> C n-k H 2(n-k)+2 + C k H 2k
alkane alkane alkene
with long chain

The resulting hydrocarbons can be cracked again to form alkanes and alkenes with an even shorter chain of carbon atoms in the molecule:

Conventional thermal cracking produces a lot of low molecular weight gaseous hydrocarbons, which can be used as raw materials for the production of alcohols. carboxylic acids, high molecular weight compounds (for example, polyethylene).

Catalytic cracking occurs in the presence of catalysts, which use natural aluminosilicates of the composition rAl2O3" m8Iu2-

Cracking with the use of catalysts leads to the formation of hydrocarbons having a branched or closed chain of carbon atoms in the molecule. The content of hydrocarbons of this structure in motor fuel significantly increases its quality, primarily the resistance to detonation - the octane number of gasoline.

Cracking of petroleum products occurs at high temperatures, so carbon deposits (soot) often form, contaminating the surface of the catalyst, which sharply reduces its activity.

Cleaning the surface of the catalyst from carbon deposits - its regeneration - is the main condition for the practical implementation of catalytic cracking. The simplest and cheapest way to regenerate a catalyst is to roast it, during which carbon deposits are oxidized with atmospheric oxygen. Gaseous oxidation products (mainly carbon dioxide and sulfur dioxide) are removed from the surface of the catalyst.

Catalytic cracking is a heterogeneous process in which solid (catalyst) and gaseous (hydrocarbon vapor) substances participate. It is obvious that catalyst regeneration - the interaction of solid soot with atmospheric oxygen - is also a heterogeneous process.

Heterogeneous reactions(gas - solid) flow faster as the surface area of the solid increases. Therefore, the catalyst is crushed, and its regeneration and cracking of hydrocarbons is carried out in a “fluidized bed”, familiar to you from the production of sulfuric acid.

The cracking feedstock, such as gas oil, enters a conical reactor. The lower part of the reactor has a smaller diameter, so the flow rate of raw material vapor is very high. Moving with high speed gas captures catalyst particles and carries them away into top part reactor, where due to an increase in its diameter the flow rate decreases. Under the influence of gravity, catalyst particles fall into the lower, narrower part of the reactor, from where they are carried upward again. Thus, each grain of catalyst is in constant movement and is washed from all sides by a gaseous reagent.

Some catalyst grains enter the outer, wider part of the reactor and, not encountering resistance to the gas flow, fall to the lower part, where they are picked up by the gas flow and carried into the regenerator. There, in the “fluidized bed” mode, the catalyst is fired and returned to the reactor.

Thus, the catalyst circulates between the reactor and the regenerator, and gaseous products of cracking and roasting are removed from them.

The use of cracking catalysts makes it possible to slightly increase the reaction rate, reduce its temperature, and improve the quality of cracking products.

The resulting hydrocarbons of the gasoline fraction mainly have a linear structure, which leads to low detonation resistance of the resulting gasoline.

We will consider the concept of “knock resistance” later, for now we will only note that hydrocarbons with molecules of a branched structure have significantly greater detonation resistance. It is possible to increase the proportion of isomeric branched hydrocarbons in the mixture formed during cracking by adding isomerization catalysts to the system.

Oil fields contain, as a rule, large accumulations of so-called associated petroleum gas, which collects above the oil in the earth's crust and is partially dissolved in it under the pressure of the overlying rocks. Like oil, associated petroleum gas is a valuable natural source of hydrocarbons. It contains mainly alkanes, whose molecules contain from 1 to 6 carbon atoms. It is obvious that the composition of associated petroleum gas is much poorer than oil. However, despite this, it is also widely used both as a fuel and as a raw material for the chemical industry. Just a few decades ago, in most oil fields, associated petroleum gas was burned as a useless supplement to oil. Currently, for example, in Surgut, the richest oil reserve in Russia, the cheapest electricity in the world is generated using associated petroleum gas as fuel.

As already noted, associated petroleum gas, compared to natural gas, is richer in composition in various hydrocarbons. Dividing them into fractions, we get:

Gas gasoline is a highly volatile mixture consisting mainly of lenthane and hexane;

A propane-butane mixture, consisting, as the name implies, of propane and butane and easily turning into a liquid state when the pressure increases;

Dry gas is a mixture containing mainly methane and ethane.

Gasoline, being a mixture of volatile components with a small molecular weight, evaporates well even at low temperatures. This makes it possible to use gas gasoline as fuel for internal combustion engines in the Far North and as an additive to motor fuel, making it easier to start engines in winter conditions.

The propane-butane mixture in the form of liquefied gas is used as household fuel (the familiar gas cylinders at the dacha) and for filling lighters. The gradual transition of road transport to liquefied gas is one of the main ways to overcome the global fuel crisis and solve environmental problems.

Dry gas, close in composition to natural gas, is also widely used as fuel.

However, the use of associated petroleum gas and its components as fuel is far from the most promising way to use it.

It is much more efficient to use the components of associated petroleum gas as raw materials for chemical production. From the alkanes that make up associated petroleum gas, hydrogen, acetylene, unsaturated and aromatic hydrocarbons and their derivatives are obtained.

Gaseous hydrocarbons can not only accompany oil in the earth's crust, but also form independent accumulations - natural gas deposits.

Natural gas - a mixture of gaseous saturated hydrocarbons with a low molecular weight. The main component of natural gas is methane, the share of which, depending on the field, ranges from 75 to 99% by volume. In addition to methane, natural gas includes ethane, propane, butane and isobutane, as well as nitrogen and carbon dioxide.

Like associated petroleum, natural gas is used both as a fuel and as a raw material for the production of a variety of organic and inorganic substances. You already know that hydrogen, acetylene and methyl alcohol, formaldehyde and formic acid, and many other organic substances are obtained from methane, the main component of natural gas. Natural gas is used as fuel in power plants, in boiler systems for water heating of residential and industrial buildings, in blast furnace and open-hearth industries. By striking a match and lighting the gas in the kitchen gas stove of a city house, you “trigger” a chain reaction of oxidation of alkanes that make up natural gas. In addition to oil, natural and associated petroleum gases, coal is a natural source of hydrocarbons. 0n forms thick layers in the bowels of the earth, its proven reserves significantly exceed oil reserves. Like oil, coal contains a large amount of various organic substances. In addition to organic substances, it also contains inorganic substances, such as water, ammonia, hydrogen sulfide and, of course, carbon itself - coal. One of the main methods of processing coal is coking - calcination without air access. As a result of coking, which is carried out at a temperature of about 1000 °C, the following are formed:

Thus, associated petroleum and natural gases, coal are not only the most valuable sources of hydrocarbons, but also part of a unique storehouse of irreplaceable natural resources, the careful and reasonable use of which is a necessary condition for the progressive development of human society.

1. List the main natural sources of hydrocarbons. What organic substances are included in each of them? What do their compositions have in common?

2. Describe the physical properties of oil. Why doesn't it have a constant boiling point?

3. Summarizing media reports, describe the environmental disasters caused by oil leaks and how to overcome their consequences.

4. What is rectification? What is this process based on? Name the fractions obtained as a result of oil rectification. How are they different from each other?

5. What is cracking? Give equations for three reactions corresponding to the cracking of petroleum products.

6. What types of cracking do you know? What do these processes have in common? How are they different from each other? What is fundamental difference different types of cracking products?

7. Why does associated petroleum gas have this name? What are its main components and their uses?

8. How does natural gas differ from associated petroleum gas? What do their compositions have in common? Give the combustion reaction equations for all components of associated petroleum gas known to you.

9. Give reaction equations that can be used to obtain benzene from natural gas. Specify the conditions for these reactions.

10. What is coking? What are its products and their composition? Give equations of reactions characteristic of the products of coking coal known to you.

11. Explain why burning oil, coal and associated petroleum gas is far from the most rational way to use them.

Natural sources of hydrocarbons are fossil fuels - oil and

gas, coal and peat. Crude oil and gas deposits arose 100-200 million years ago

back from microscopic marine plants and animals that turned out to be

included in sedimentary rocks formed on the seabed, Unlike

This coal and peat began to form 340 million years ago from plants,

growing on land.

Natural gas and crude oil are commonly found with water in

oil-bearing layers located between rock layers (Fig. 2). Term

“natural gas” also applies to gases that are formed in natural

conditions resulting from coal decomposition. Natural gas and crude oil

are being developed on all continents, with the exception of Antarctica. The largest

Natural gas producers in the world are Russia, Algeria, Iran and

United States. The largest producers crude oil are

Venezuela, Saudi Arabia, Kuwait and Iran.

Natural gas consists mainly of methane (Table 1).

Crude oil is an oily liquid whose color may vary

be very diverse - from dark brown or green to almost

colorless. It contains large number alkanes. Among them there are

straight alkanes, branched alkanes and cycloalkanes with number of atoms

carbon from five to 40. The industrial name of these cycloalkanes is nachta. IN

crude oil also contains approximately 10% aromatic

hydrocarbons, as well as small amounts of other compounds containing

sulfur, oxygen and nitrogen.

Table 1 Composition of natural gas

Coal is the oldest source energy with which you are familiar

humanity. It is a mineral (Fig. 3), which was formed from

plant matter in the process of metamorphism. Metamorphic

are called rocks, the composition of which has undergone changes under conditions

high pressures, as well as high temperatures. The product of the first stage in

the process of coal formation is peat, which is

decomposed organic matter. Coal is formed from peat after

it is covered with sedimentary rocks. These sedimentary rocks are called

overloaded. Overloaded sediment reduces the moisture content of the peat.

Three criteria are used in the classification of coals: purity (determined

relative carbon content in percent); type (defined

composition of the original plant matter); grade (depending on

degree of metamorphism).

Table 2 Carbon content of some fuels and their calorific value

ability

The lowest grade types of fossil coals are brown coal and

lignite (Table 2). They are closest to peat and are characterized relatively

characterized by lower moisture content and is widely used in

industry. The driest and hardest type of coal is anthracite. His

used for heating homes and cooking.

Recently, thanks to technological advances, it has become increasingly

economical gasification of coal. Coal gasification products include

carbon monoxide, carbon dioxide, hydrogen, methane and nitrogen. They are used in

as a gaseous fuel or as a raw material for the production of various

chemical products and fertilizers.

Coal, as described below, serves important source raw materials for obtaining

aromatic compounds. Coal represents

is a complex mixture of chemicals that include carbon,

hydrogen and oxygen, as well as small amounts of nitrogen, sulfur and other impurities

elements. In addition, the composition of coal, depending on its type, includes

different amounts of moisture and different minerals.

Hydrocarbons occur naturally not only in fossil fuels, but also in

in some materials biological origin. Natural rubber

is an example of a natural hydrocarbon polymer. rubber molecule

consists of thousands of structural units representing methyl buta-1,3-diene

(isoprene);

Natural rubber. Approximately 90% natural rubber, which

currently mined all over the world, obtained from Brazilian

rubber tree Hevea brasiliensis, cultivated mainly in

equatorial countries of Asia. The sap of this tree, which is latex

(colloidal aqueous solution of polymer), collected from cuts made with a knife on

bark Latex contains approximately 30% rubber. His tiny pieces

suspended in water. The juice is poured into aluminum containers, where acid is added,

causing the rubber to coagulate.

Many other natural compounds also contain isoprene structures.

fragments. For example, limonene contains two isoprene units. Limonene

is the main one integral part oils extracted from citrus peels,

such as lemons and oranges. This connection belongs to connection class,

called terpenes. Terpenes contain 10 carbon atoms (C) in their molecules

10-compounds) and include two isoprene fragments connected to each other

each other sequentially (“head to tail”). Compounds with four isoprene

fragments (C 20 compounds) are called diterpenes, and with six

isoprene fragments - triterpenes (C 30 compounds). Squalene,

which is found in shark liver oil is a triterpene.

Tetraterpenes (C 40 compounds) contain eight isoprene

fragments. Tetraterpenes are found in pigments of vegetable and animal fats

origin. Their color is due to the presence of a long conjugate system

double bonds. For example, β-carotene is responsible for the characteristic orange color

carrot coloring.

Oil and coal processing technology

At the end of the 19th century. Under the influence of progress in the field of heat and power engineering, transport, engineering, military and a number of other industries, demand has increased immeasurably and an urgent need has arisen for new types of fuel and chemical products.

At this time, the oil refining industry was born and rapidly progressed. A huge impetus to the development of the oil refining industry was given by the invention and rapid spread of the internal combustion engine running on petroleum products. The technology for processing coal, which not only serves as one of the main types of fuel, but, what is especially noteworthy, became a necessary raw material for the chemical industry during the period under review, also developed intensively. A major role in this matter belonged to coke chemistry. Coke plants, which previously supplied coke to the iron and steel industry, turned into coke-chemical enterprises, which also produced a number of valuable chemical products: coke oven gas, crude benzene, coal tar and ammonia.

Based on the products of oil and coal processing, the production of synthetic organic substances and materials began to develop. They are widely used as raw materials and semi-finished products in various branches of the chemical industry.

Ticket#10

Natural sources of hydrocarbons. Natural sources of hydrocarbons – Knowledge Hypermarket

Answers to paragraph 19

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