Natural sources of hydrocarbons. Natural gas: composition, use as a fuel

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hydrocarbons

Hydrocarbons are compounds consisting only of carbon and hydrogen atoms.

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

Cyclic (carbocyclic) compounds are called compounds that include one or more cycles 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 of molecules is open chains.

These chains can be formed by single bonds (CnH2n+2 alkanes), contain one double bond (CnH2n alkenes), two or more double bonds (dienes or polyenes), one triple bond (CnH2n-2 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. 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 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 consider them in more detail.

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 production (deposit), it can, in addition to alkanes, 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 dark (from brown to black) color with a characteristic odor, insoluble in water. Its density is less than that of water, therefore, getting into it, oil spreads over the surface, preventing the dissolution of oxygen and other air gases in water.

Obviously, getting into natural water bodies, oil causes the death of microorganisms and animals, leading to environmental disasters and even catastrophes. There are bacteria that can use the components of oil 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 safe and promising way to combat oil pollution in the process of its production, transportation and processing.

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 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, sulfur-containing compounds and subjected to the so-called fractional distillation, or rectification.

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

In the process of rectification, oil is divided into the following fractions:

Rectification gases - 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 of oil distillation - fuel oil - contains hydrocarbons with a number of carbon atoms from 18 to 50. By distillation under reduced pressure, solar oil (С18Н28-С25Н52), lubricating oils (С28Н58-С38Н78), vaseline and paraffin are obtained from fuel oil - fusible mixtures of solid hydrocarbons.

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

Associated petroleum gas

Oil fields contain, as a rule, large accumulations of the so-called associated petroleum gas, which is collected above the oil in the earth's crust and 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, which have from 1 to 6 carbon atoms in their molecules. Obviously, 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. Until a few decades ago, in most oil fields, associated petroleum gas was burned as a useless addition to oil.

At present, for example, in Surgut, Russia's richest oil pantry, the world's cheapest electricity is generated using associated petroleum gas as fuel.

Associated petroleum gas is richer in composition of various hydrocarbons than natural gas. Dividing them into fractions, they get:

Natural gasoline - a highly volatile mixture consisting mainly of lentane and hexane;

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

Dry gas - a mixture containing mainly methane and ethane.

Natural 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 a fuel for internal combustion engines in the Far North and as an additive to motor fuel, which makes it easier to start engines in winter conditions.

A propane-butane mixture in the form of liquefied gas is used as household fuel (gas cylinders familiar to you in the country) 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 a fuel.

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

It is much more efficient to use associated petroleum gas components as feedstock for chemical production. Hydrogen, acetylene, unsaturated and aromatic hydrocarbons and their derivatives are obtained from alkanes, which are part of 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 small 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 contains ethane, propane, butane and isobutane, as well as nitrogen and carbon dioxide.

Like associated petroleum gas, natural gas is used both as a fuel and as a raw material for the production of various 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. As a fuel, natural gas is used in power plants, in boiler systems for water heating of residential buildings and industrial buildings, in blast furnace and open-hearth production.

Striking a match and lighting the gas in the kitchen gas stove of a city house, you "start" chain reaction oxidation of alkanes that are part of natural gas.

Coal

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

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

In addition to organic, it also includes inorganic substances, such as, for example, water, ammonia, hydrogen sulfide and, of course, carbon itself - coal. One of the main ways of coal processing 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 includes hydrogen, methane, carbon monoxide and carbon dioxide, impurities of ammonia, nitrogen and other gases;
coal tar containing several hundred different organic substances, including benzene and its homologues, phenol and aromatic alcohols, naphthalene and various heterocyclic compounds;
supra-tar, or ammonia water, containing, as the name implies, dissolved ammonia, as well as phenol, hydrogen sulfide and other substances;
coke - solid residue of 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 cannot be overestimated.

Conclusion: thus, oil, associated petroleum and natural gases, coal are not only the most valuable sources of hydrocarbons, but also part of the unique pantry 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 matter comes from natural sources. In the process of synthesis of organic compounds, natural and associated gases, coal and brown coal, oil, oil shale, peat, products of animal and vegetable 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 the following compounds: hydrogen (in small quantities) - H2; carbon dioxide - CO2; helium - Not; nitrogen - N2; hydrogen sulfide - H2S.

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

Chemical composition
The main part of natural gas is methane (CH4) - up to 98%. The composition of natural gas may also include heavier hydrocarbons:
* ethane (C2H6),
* propane (C3H8),
* butane (C4H10)
- homologues of methane, 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.

In order to be able to detect a leak by smell, a small amount of mercaptans, which have a strong unpleasant odor, are added to the gas.

What are the advantages of natural gas over other fuels

1. simplified extraction (does not need artificial pumping)

2. ready for use without intermediate processing (distillation)

transportation in both gaseous and liquid state.

4. minimal emissions of harmful substances during combustion.

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

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

7. use in larger sectors of the economy than other fuels.

a sufficient amount in the bowels of Russia.

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

10. high combustion temperature for use in national economy flow charts, etc., etc.

Application in the chemical industry

It is used to produce plastics, alcohol, rubber, organic acids. Only with the use of natural gas it is possible to synthesize such chemical substances, which simply cannot be found in nature, for example, polyethylene.

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

Hydrogen cyanide, already 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 layers, which are quite widely used in industry and in everyday life.

It also produces acetate silk.

Natural gas is one of the best 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 is burned, much less harmful substances appear when compared with other types of fuel.

The most important oil products

From oil in the process of processing, 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, vaseline , ceresin), petroleum bitumen, carbon black (soot), petroleum acids and their derivatives.

Liquid fuels obtained by oil refining are divided into motor and boiler fuels.

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

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

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

Individual hydrocarbons obtained as a result of oil refining and oil gases, serve as raw materials for the production of polymers and products of organic synthesis.

Of these, the most important are the limiting ones - methane, ethane, propane, butane; unsaturated - ethylene, propylene; aromatic - benzene, toluene, xylenes. Also, oil refining products are saturated hydrocarbons with a large 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 you know?

Natural sources of hydrocarbons are fossil fuels.

Most organic matter comes from natural sources. In the process of synthesis of organic compounds, natural and associated gases, coal and brown coal, oil, oil shale, peat, products of animal and vegetable origin are used as raw materials.

12Next ⇒

Answers to paragraph 19

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

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

3. What advantages does natural gas have over other fuels? What is natural gas used for in the chemical industry?
Natural gas, compared to other sources of hydrocarbons, is the easiest to extract, transport and process.

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

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

5. What is the difference between associated petroleum gases and natural gas?
Associated gases are volatile hydrocarbons dissolved in oil.

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

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 for transmission, industrial, lubricant-cooling emulsions for machine tools, etc.

How is oil refining carried out?

10. What is oil cracking? Write an equation for the reactions of hydrocarbon splitting and during this process.

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

12. What is the difference between thermal cracking and catalytic cracking? Describe thermal and catalytic cracked gasolines.
In thermal cracking, it is necessary to heat the reactants to high temperatures, in catalytic cracking, the introduction of a catalyst reduces the activation energy of the reaction, which makes it possible to significantly reduce the reaction temperature.

How practically can cracked gasoline be distinguished from straight-run gasoline?
Cracked gasoline has a higher octane number than straight run gasoline, i.e. more resistant to detonation and recommended for use in internal combustion engines.

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

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

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

It is used for iron smelting, as a smokeless fuel, reducing agent iron ore, baking powder for charge materials.

17. What are the main products receive:
a) from coal tar; b) from tar water; c) from coke oven gas? Where are they applied? 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 is the difference between the methods of obtaining aromatic hydrocarbons from the coking products of coal and oil? Write the equations for the corresponding reactions.
They differ in production methods: primary oil refining is based on a difference in physical properties various fractions, and coking is based purely on the chemical properties of 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 the entire production, etc.

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

Task 1.

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

Task 2.

What volume of air (N.O.) 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 by burning 5 moles of octane (n.o.).

The main sources of hydrocarbons on our planet are natural gas, oil and coal. Millions of years of conservation in the bowels of the earth have withstood the most stable of hydrocarbons: saturated and aromatic.

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

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

Other substances are also present in oil: heteroatomic organic compounds (containing 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 large part of the atmosphere of Uranus and is responsible for its light turquoise color as seen through a telescope. The atmosphere of Titan, the largest satellite of Saturn, consists mainly of nitrogen, but also contains hydrocarbons methane, ethane, propane, ethine, propyne, butadiine and their derivatives; sometimes it rains methane, 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 effect of solar radiation.

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

Petroleum products are currently used in almost all industries.

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

From the fuel oil remaining after the distillation of oil during atmospheric pressure, under the action of vacuum, components of a large 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 the process 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 fuels and various solvents, and some are raw materials for the production of new organic compounds and materials for various industries.

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

Of course, sooner or later, nature will restore balance, but this can turn into serious problems for humans. Therefore, it is necessary new technologies in order to move away from the use of hydrocarbons as a fuel in the future.

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

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

By reserves natural gas the first place in the world belongs to our country. Natural gas contains low molecular weight hydrocarbons. It has the following approximate composition (by volume): 80-98% methane, 2-3% of its closest homologues - ethane, propane, butane and a small amount of impurities - hydrogen sulfide H 2 S, nitrogen N 2 , noble gases, carbon monoxide (IV ) CO 2 and water vapor H 2 O . The composition of the gas is specific to each field. There is the following pattern: the higher the relative molecular mass hydrocarbon, the less it is contained in natural gas.

Natural gas is widely used as a cheap fuel with high calorific value (combustion of 1m 3 releases up to 54,400 kJ). It is one of the best types of fuel for domestic and industrial needs. In addition, natural gas is a valuable raw material for the chemical industry: the production of acetylene, ethylene, hydrogen, soot, various plastics, acetic acid, dyes, medicines and other products.

Associated petroleum gases are in deposits together with oil: they are dissolved in it and are located above the oil, forming a gas “cap”. When extracting oil to the surface, gases are separated from it due to a sharp drop in pressure. Previously, associated gases were not used and were flared during oil production. Currently, they are captured and used as fuel and valuable chemical raw materials. Associated gases contain less methane than natural gas, but more ethane, propane, butane and higher hydrocarbons. In addition, they contain basically the same impurities as in natural gas: H 2 S, N 2, noble gases, H 2 O vapor, CO 2 . Individual hydrocarbons (ethane, propane, butane, etc.) are extracted from associated gases, their processing makes it possible to obtain unsaturated hydrocarbons by dehydrogenation - propylene, butylene, butadiene, from which rubbers and plastics are then synthesized. A mixture of propane and butane (liquefied gas) is used as a household fuel. Natural gasoline (a mixture of pentane and hexane) is used as an additive to gasoline for better ignition of the fuel when starting the engine. Oxidation of hydrocarbons produces organic acids, alcohols and other products.

Oil- oily flammable liquid of dark brown or almost black color with a characteristic odor. It is lighter than water (= 0.73–0.97 g / cm 3), practically insoluble in water. By composition, oil is a complex mixture of hydrocarbons of various molecular weights, so it does not have a specific boiling point.

Oil consists mainly of liquid hydrocarbons (solid and gaseous hydrocarbons are dissolved in them). Usually these are alkanes (mainly of a normal structure), cycloalkanes and arenes, the ratio of which in oils from various fields varies widely. Ural oil contains more arenes. In addition to hydrocarbons, oil contains oxygen, sulfur and nitrogenous organic compounds.

Crude oil is not normally used. To obtain technically valuable products from oil, it is subjected to processing.

Primary processing oil consists in its distillation. Distillation is carried out at refineries after the separation of associated gases. During the distillation of oil, light oil products are obtained:

gasoline ( t kip \u003d 40–200 ° С) contains hydrocarbons С 5 -С 11,

naphtha ( t kip \u003d 150–250 ° С) contains hydrocarbons С 8 -С 14,

kerosene ( t kip \u003d 180–300 ° С) contains hydrocarbons С 12 -С 18,

gas oil ( t kip > 275 °C),

and in the remainder - a viscous black liquid - fuel oil.

Oil is subjected to further processing. It is distilled under reduced pressure (to prevent decomposition) and lubricating oils are isolated: spindle, engine, cylinder, etc. Petroleum jelly and paraffin are isolated from fuel oil of some grades of oil. The residue of fuel oil after distillation - tar - after partial oxidation is used to produce asphalt. The main disadvantage of oil refining is the low yield of gasoline (no more than 20%).

Oil distillation products have various uses.

Petrol used in large quantities as aviation and automotive fuel. It usually consists of hydrocarbons containing an average of 5 to 9 C atoms in molecules. Naphtha It is used as a fuel for tractors, as well as a solvent in the paint and varnish industry. Large quantities are processed into gasoline. Kerosene It is used as a fuel for tractors, jet planes and rockets, as well as for domestic needs. solar oil - gas oil- used as a motor fuel, and lubricating oils- for lubricating mechanisms. Petrolatum used in medicine. It consists of a mixture of liquid and solid hydrocarbons. Paraffin used to obtain higher carboxylic acids, to impregnate wood in the production of matches and pencils, for the manufacture of candles, shoe polish, etc. It consists of a mixture of solid hydrocarbons. fuel oil in addition to processing into lubricating oils and gasoline, it is used as boiler liquid fuel.

At secondary processing methods oil is a change in the structure of the hydrocarbons that make up its composition. Among these methods great importance has cracking of oil hydrocarbons, carried out in order to increase the yield of gasoline (up to 65-70%).

Cracking- the process of splitting hydrocarbons contained in oil, as a result of which hydrocarbons with a smaller number of C atoms in the molecule are formed. There are two main types of cracking: thermal and catalytic.

Thermal cracking is carried out by heating the feedstock (fuel oil, etc.) at a temperature of 470–550 °C and a pressure of 2–6 MPa. In this case, hydrocarbon molecules with a large number of C atoms are split into molecules with a smaller number of atoms of both saturated and unsaturated hydrocarbons. For example:

(radical mechanism),

In this way, mainly automobile gasoline is obtained. Its output from oil reaches 70%. Thermal cracking was discovered by Russian engineer V.G. Shukhov in 1891.

catalytic cracking is carried out in the presence of catalysts (usually aluminosilicates) at 450–500 °C and atmospheric pressure. In this way, aviation gasoline is obtained with a yield of up to 80%. This type of cracking is mainly subjected to kerosene and gas oil fractions of oil. In catalytic cracking, along with cleavage reactions, isomerization reactions occur. As a result of the latter, saturated hydrocarbons with a branched carbon skeleton of molecules are formed, which improves the quality of gasoline:

Catalytic cracked gasoline is of higher quality. The process of obtaining it proceeds much faster, with less consumption of thermal energy. In addition, relatively many branched-chain hydrocarbons (isocompounds) are formed during catalytic cracking, which are of great value for organic synthesis.

At t= 700 °C and above, pyrolysis occurs.

Pyrolysis- decomposition of organic substances without air access at high temperature. During oil pyrolysis, the main reaction products are unsaturated gaseous hydrocarbons (ethylene, acetylene) and aromatic hydrocarbons - benzene, toluene, etc. Since oil pyrolysis is one of the most important ways to obtain aromatic hydrocarbons, this process is often called oil aromatization.

Aromatization– transformation of alkanes and cycloalkanes into arenes. When heavy fractions of petroleum products are heated in the presence of a catalyst (Pt or Mo), hydrocarbons containing 6–8 C atoms per molecule are converted into aromatic hydrocarbons. These processes occur during reforming (upgrading of gasoline).

Reforming- this is the aromatization of gasolines, carried out as a result of heating them in the presence of a catalyst, for example, Pt. Under these conditions, alkanes and cycloalkanes are converted into aromatic hydrocarbons, as a result of which the octane number of gasoline also increases significantly. Aromatization is used to obtain individual aromatic hydrocarbons (benzene, toluene) from gasoline fractions of oil.

In recent years, petroleum hydrocarbons have been widely used as a source of chemical raw materials. Different ways from them are obtained substances necessary for the production of plastics, synthetic textile fibers, synthetic rubber, alcohols, acids, synthetic detergents, explosives, pesticides, synthetic fats, etc.

Coal just like natural gas and oil, it is a source of energy and a valuable chemical raw material.

The main method of coal processing is coking(dry distillation). During coking (heating up to 1000 °С - 1200 °С without air access), various products are obtained: coke, coal tar, tar water and coke oven gas (scheme).

Scheme

Coke is used as a reducing agent in the production of iron in metallurgical plants.

Coal tar serves as a source of aromatic hydrocarbons. It is subjected to rectification distillation and benzene, toluene, xylene, naphthalene, as well as phenols, nitrogen-containing compounds, etc. are obtained.

Ammonia, ammonium sulfate, phenol, etc. are obtained from tar water.

Coke oven gas is used to heat coke ovens (combustion of 1 m 3 releases about 18,000 kJ), but it is mainly subjected to chemical processing. So, hydrogen is extracted from it for the synthesis of ammonia, which is then used to produce nitrogen fertilizers, as well as methane, benzene, toluene, ammonium sulfate, and ethylene.

Hydrocarbons are of great economic importance, since they serve as the most important type of raw material for obtaining almost all products of the modern industry of organic synthesis and are widely used for energy purposes. They seem to accumulate solar heat and the energy that is released when burned. Peat, coal, oil shale, oil, natural and associated petroleum gases contain carbon, the combination of which with oxygen during combustion is accompanied by the release of heat.

coal	peat	oil	natural gas
solid	solid	liquid	gas
without smell	without smell	Strong smell	without smell
uniform composition	uniform composition	mixture of substances	mixture of substances
a dark-colored rock with a high content of combustible matter resulting from the burial of accumulations of various plants in the sedimentary strata	accumulation of semi-decomposed plant mass accumulated at the bottom of swamps and overgrown lakes	natural combustible oily liquid, consists of a mixture of liquid and gaseous hydrocarbons	a mixture of gases formed in the bowels of the Earth during the anaerobic decomposition of organic substances, the gas belongs to the group of sedimentary rocks
Calorific value - the number of calories released by burning 1 kg of fuel
7 000 - 9 000	500 - 2 000	10000 - 15000	?

Coal.

Coal has always been a promising raw material for energy and many chemical products.

Since the 19th century, the first major consumer of coal has been transport, then coal began to be used for the production of electricity, metallurgical coke, the production of various products during chemical processing, carbon-graphite structural materials, plastics, mountain wax, synthetic, liquid and gaseous high-calorie fuels, high-nitrogen acids for the production of fertilizers.

Coal is a complex mixture of macromolecular compounds, which include the following elements: C, H, N, O, S. Coal, like oil, contains a large amount of various organic substances, as well as inorganic substances, such as, for example, water, ammonia, hydrogen sulfide and of course carbon itself - coal.

Processing of hard coal goes in three main directions: coking, hydrogenation and incomplete combustion. One of the main ways of coal processing is coking– calcination without air access in coke ovens at a temperature of 1000–1200°C. At this temperature, without access to oxygen, coal undergoes the most complex chemical transformations, as a result of which coke and volatile products are formed:

1. coke gas (hydrogen, methane, carbon monoxide and carbon dioxide, impurities of ammonia, nitrogen and other gases);

2. coal tar (several hundred different organic substances, including benzene and its homologues, phenol and aromatic alcohols, naphthalene and various heterocyclic compounds);

3. supra-tar, or ammonia, water (dissolved ammonia, as well as phenol, hydrogen sulfide and other substances);

4. coke (solid residue of coking, practically pure carbon).

The cooled coke is sent to metallurgical plants.

When the volatile products (coke oven gas) are cooled, coal tar and ammonia water condense.

Passing uncondensed products (ammonia, benzene, hydrogen, methane, CO 2 , nitrogen, ethylene, etc.) through a solution of sulfuric acid, ammonium sulfate is isolated, which is used as a mineral fertilizer. Benzene is taken up in the solvent and distilled off from the solution. After that, coke gas is used as a fuel or as a chemical raw material. Coal tar is obtained in small quantities (3%). But, given the scale of production, coal tar is considered as a raw material for obtaining a number of organic substances. If products boiling up to 350 ° C are driven away from the resin, then a solid mass remains - pitch. It is used for the manufacture of varnishes.

Hydrogenation of coal is carried out at a temperature of 400–600°C under a hydrogen pressure of up to 25 MPa in the presence of a catalyst. In this case, a mixture of liquid hydrocarbons is formed, which can be used as a motor fuel. Obtaining liquid fuel from coal. Liquid synthetic fuels are high-octane gasoline, diesel and boiler fuels. To obtain liquid fuel from coal, it is necessary to increase its hydrogen content by hydrogenation. Hydrogenation is carried out using multiple circulation, which allows you to turn into a liquid and gases the entire organic mass of coal. The advantage of this method is the possibility of hydrogenation of low-grade brown coal.

Coal gasification will make it possible to use low-quality brown and black coals at thermal power plants without polluting environment sulfur compounds. This is the only method for obtaining concentrated carbon monoxide (carbon monoxide) CO. Incomplete combustion of coal produces carbon monoxide (II). On a catalyst (nickel, cobalt) at normal or elevated pressure, hydrogen and CO can be used to produce gasoline containing saturated and unsaturated hydrocarbons:

nCO + (2n+1)H 2 → C n H 2n+2 + nH 2 O;

nCO + 2nH 2 → C n H 2n + nH 2 O.

If dry distillation of coal is carried out at 500–550°C, then tar is obtained, which, along with bitumen, is used in the construction industry as a binder in the manufacture of roofing, waterproofing coatings (roofing material, roofing felt, etc.).

In nature, coal is found in the following regions: the Moscow region, the South Yakutsk basin, the Kuzbass, the Donbass, the Pechora basin, the Tunguska basin, the Lena basin.

Natural gas.

Natural gas is a mixture of gases, the main component of which is methane CH 4 (from 75 to 98% depending on the field), the rest is ethane, propane, butane and a small amount of impurities - nitrogen, carbon monoxide (IV), hydrogen sulfide and vapors water, and, almost always, hydrogen sulfide and organic compounds of oil - mercaptans. It is they who give the gas a specific unpleasant odor, and when burned, they lead to the formation of toxic sulfur dioxide SO 2.

Generally, the higher the molecular weight of the hydrocarbon, the less of it is contained in natural gas. The composition of natural gas from different fields is not the same. Its average composition as a percentage by volume is as follows:

Methane is formed during anaerobic (without air access) fermentation of plant and animal residues, therefore it is formed in bottom sediments and is called "marsh" gas.

Methane deposits in hydrated crystalline form, the so-called methane hydrate, found under a layer of permafrost and at great depths of the oceans. At low temperatures (−800ºC) and high pressures methane molecules are located in voids crystal lattice water ice. In the ice voids of one cubic meter of methane hydrate, 164 cubic meters of gas are "mothballed".

Pieces of methane hydrate look like dirty ice, but in air they burn with a yellow-blue flame. An estimated 10,000 to 15,000 gigatonnes of carbon are stored on the planet in the form of methane hydrate (a giga is 1 billion). Such volumes are many times greater than all currently known reserves of natural gas.

Natural gas is renewable natural resource, as it is synthesized in nature continuously. It is also called "biogas". Therefore, many environmental scientists today associate the prospects for the prosperous existence of mankind precisely with the use of gas as an alternative fuel.

As a fuel, natural gas has great advantages over solid and liquid fuels. Its calorific value is much higher, when burned, it does not leave ash, the combustion products are much more environmentally friendly. Therefore, about 90% of the total volume of produced natural gas is burned as fuel at thermal power plants and boiler houses, in thermal processes at industrial enterprises and in everyday life. About 10% of natural gas is used as a valuable raw material for the chemical industry: to produce hydrogen, acetylene, soot, various plastics, and medicines. Methane, ethane, propane and butane are isolated from natural gas. Products that can be obtained from methane are of great industrial importance. Methane is used for the synthesis of many organic substances - synthesis gas and further synthesis of alcohols based on it; solvents (carbon tetrachloride, methylene chloride, etc.); formaldehyde; acetylene and soot.

Natural gas forms independent deposits. The main deposits of natural combustible gases are located in the Northern and Western Siberia, the Volga-Ural basin, in the North Caucasus (Stavropol), in the Komi Republic, Astrakhan region, Barents Sea.

During the lesson, you will be able to study the topic “Natural sources of hydrocarbons. Oil refining". More than 90% of all energy currently consumed by mankind is extracted from fossil natural organic compounds. You will learn about natural resources (natural gas, oil, coal), what happens to oil after it is extracted.

Topic: Limit hydrocarbons

Lesson: Natural Sources of Hydrocarbons

About 90% of the energy consumed by modern civilization is generated by burning natural fossil fuels - natural gas, oil and coal.

Russia is a country rich in natural fossil fuels. There are large reserves of oil and natural gas in Western Siberia and the Urals. Hard coal is mined in the Kuznetsk, South Yakutsk basins and other regions.

Natural gas consists on average of 95% by volume of methane.

In addition to methane, natural gas from various fields contains nitrogen, carbon dioxide, helium, hydrogen sulfide, and other light alkanes - ethane, propane and butanes.

Natural gas is extracted from underground deposits, where it is under high pressure. Methane and other hydrocarbons are formed from organic substances of plant and animal origin during their decomposition without air access. Methane is produced constantly and currently as a result of the activity of microorganisms.

Methane found on planets solar system and their companions.

Pure methane is odorless. However, the gas used in everyday life has a characteristic unpleasant odor. This is the smell of special additives - mercaptans. The smell of mercaptans allows you to detect a leak of domestic gas in time. Mixtures of methane with air are explosive in a wide range of ratios - from 5 to 15% of gas by volume. Therefore, if you smell gas in the room, you can not only light a fire, but also use electrical switches. The smallest spark can cause an explosion.

Rice. 1. Oil from different fields

Oil- a thick liquid like oil. Its color is from light yellow to brown and black.

Rice. 2. Oil fields

Oil from different fields varies greatly in composition. Rice. 1. The main part of oil is hydrocarbons containing 5 or more carbon atoms. Basically, these hydrocarbons are saturated, i.e. alkanes. Rice. 2.

The composition of oil also includes organic compounds containing sulfur, oxygen, nitrogen. Oil contains water and inorganic impurities.

Gases are dissolved in oil, which are released during its extraction - associated petroleum gases. These are methane, ethane, propane, butanes with nitrogen impurities, carbon dioxide and hydrogen sulfide.

Coal, like oil, is a complex mixture. The share of carbon in it accounts for 80-90%. The rest is hydrogen, oxygen, sulfur, nitrogen and some other elements. In brown coal the proportion of carbon and organic matter is lower than in stone. Even less organic oil shale.

In industry, coal is heated to 900-1100 0 C without air. This process is called coking. The result is coke with a high carbon content, coke gas and coal tar, necessary for metallurgy. A lot of organic substances are released from the gas and tar. Rice. 3.

Rice. 3. The device of the coke oven

Natural gas and oil are the most important sources of raw materials for the chemical industry. Oil as it is produced, or "crude oil", is difficult to use even as a fuel. Therefore, crude oil is divided into fractions (from the English "fraction" - "part"), using differences in the boiling points of its constituent substances.

Oil separation method based on different temperatures boiling of its constituent hydrocarbons is called distillation or distillation. Rice. four.

Rice. 4. Products of oil refining

The fraction that is distilled from about 50 to 180 0 C is called gasoline.

Kerosene boils at temperatures of 180-300 0 C.

A thick black residue that does not contain volatile substances is called fuel oil.

There are also a number of intermediate fractions boiling in narrower ranges - petroleum ethers(40-70 0 C and 70-100 0 C), white spirit (149-204 ° C), and gas oil (200-500 0 C). They are used as solvents. Fuel oil can be distilled under reduced pressure, in this way lubricating oils and paraffin are obtained from it. Solid residue from the distillation of fuel oil - asphalt. It is used for the production of road surfaces.

Processing of associated petroleum gases is a separate industry and makes it possible to obtain a number of valuable products.

Summing up the lesson

During the lesson, you studied the topic “Natural sources of hydrocarbons. Oil refining". More than 90% of all energy currently consumed by mankind is extracted from fossil natural organic compounds. You learned about natural resources (natural gas, oil, coal), about what happens to oil after it is extracted.

Bibliography

1. Rudzitis G.E. Chemistry. Fundamentals of General Chemistry. Grade 10: textbook for educational institutions: basic level / G. E. Rudzitis, F.G. Feldman. - 14th edition. - M.: Education, 2012.

2. Chemistry. Grade 10. Profile level: studies. for general education institutions / V.V. Eremin, N.E. Kuzmenko, V.V. Lunin and others - M.: Drofa, 2008. - 463 p.

3. Chemistry. Grade 11. Profile level: textbook. for general education institutions / V.V. Eremin, N.E. Kuzmenko, V.V. Lunin and others - M.: Drofa, 2010. - 462 p.

4. Khomchenko G.P., Khomchenko I.G. Collection of problems in chemistry for those entering the universities. - 4th ed. - M .: RIA " New wave": Publisher Umerenkov, 2012. - 278 p.

Homework

1. Nos. 3, 6 (p. 74) Rudzitis G.E., Feldman F.G. Chemistry: Organic Chemistry. Grade 10: textbook for educational institutions: basic level / G. E. Rudzitis, F.G. Feldman. - 14th edition. - M.: Education, 2012.

2. What is the difference between associated petroleum gas and natural gas?

3. How is oil refining carried out?

It should be noted that hydrocarbons are widely distributed in nature. Most organic matter comes from natural sources. In the process of synthesis of organic compounds, natural and associated gases, coal and brown coal, oil, peat, products of animal and vegetable origin are used as raw materials.

Natural sources of hydrocarbons: natural gases.

Natural gases are natural mixtures of hydrocarbons of various structures and some gas impurities (hydrogen sulfide, hydrogen, carbon dioxide) that fill the rocks in the earth's crust. These compounds are formed as a result of hydrolysis of organic substances at great depths in the Earth's thickness. They are found in the free state in the form of huge accumulations - gas, gas condensate and oil and gas fields.

The main structural component of combustible natural gases is CH₄ (methane - 98%), С₂Н₆ (ethane - 4.5%), propane (С₃Н₈ - 1.7%), butane (С₄Н₁₀ - 0.8%), pentane (С₅Н₁₂ - 0 .6%). Associated petroleum gas is part of the oil in a dissolved state and is released from it due to a decrease in pressure when the oil rises to the surface. In gas and oil fields, one ton of oil contains from 30 to 300 sq. m of gas. Natural sources of hydrocarbons are a valuable fuel and raw material for the organic synthesis industry. Gas is supplied to gas processing enterprises, where it can be processed (oil, low-temperature adsorption, condensation and rectification). It is divided into separate components, each of which is used for specific purposes. For example, from methane synthesis gas, which are the basic raw materials for the production of other hydrocarbons, acetylene, methanol, methanal, chloroform.

Natural sources of hydrocarbons: oil.

Oil is a complex mixture that consists mainly of naphthenic, paraffinic and aromatic hydrocarbons. The composition of oil includes asphalt-resinous substances, mono- and disulfides, mercaptans, thiophene, thiophane, hydrogen sulfide, piperidine, pyridine and its homologues, as well as other substances. Based on the products, more than 3,000 different products are obtained using petrochemical synthesis methods, incl. ethylene, benzene, propylene, dichloroethane, vinyl chloride, styrene, ethanol, isopropanol, butylenes, various plastics, chemical fibers, dyes, detergents, drugs, explosives, etc.

Peat is a sedimentary rock of plant origin. This substance is used as a fuel (mainly for thermal power plants), chemical raw materials (for the synthesis of many organic substances), antiseptic bedding on farms, especially in poultry farms, and a component of fertilizers for gardening and field crops.

Natural sources of hydrocarbons: xylem or wood.

Xylem is a tissue of higher plants through which water and dissolved nutrients come from the rhizome of the system to the leaves, as well as other organs of the plant. It consists of cells with a stiff shell, which have a vascular conduction system. Depending on the type of wood, it contains different amounts of pectin and mineral compounds (mainly calcium salts), lipids and essential oils. Wood is used as a fuel; methyl alcohol, acetic acid, cellulose, and other substances can be synthesized from it. From some types of wood, dyes are obtained (sandalwood, logwood), tannins (oak), resins and balsams (cedar, pine, spruce), alkaloids (plants of the nightshade, poppy, ranunculus, umbrella families). Some alkaloids are used as medicines (chitin, caffeine), herbicides (anabasine), insecticides (nicotine).