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

natural springs hydrocarbons: natural gases.

Natural gases are natural mixtures of hydrocarbons of various structures and some gas impurities (hydrogen sulfide, hydrogen, carbon dioxide) that fill rocks rocks V 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.

Main structural component combustible natural gases are 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 - tissue higher plants through which water and dissolved nutrients flow from the rhizome of the system to the leaves, as well as other plant organs. It consists of cells with a stiff shell, which have a vascular conduction system. Depending on the type of wood, it contains different amount pectins 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 (Anabasin), insecticides (nicotine).

Natural source of hydrocarbons
Its main features
Oil

Multi-component mixture consisting mainly of hydrocarbons. Hydrocarbons are mainly represented by alkanes, cycloalkanes and arenes.
Associated petroleum gas

A mixture consisting almost exclusively of alkanes with a long carbon chain from 1 to 6 carbon atoms, is formed along with the extraction of oil, hence the origin of the name. There is such a tendency: the lower the molecular weight of the alkane, the more percentage in associated petroleum gas is higher.
Natural gas

A mixture consisting predominantly of low molecular weight alkanes. The main component of natural gas is methane. Its percentage, depending on the gas field, can be from 75 to 99%. In second place in terms of concentration by a wide margin is ethane, propane is even less contained, etc.

Fundamental difference natural gas from associated petroleum gas is that the proportion of propane and isomeric butanes in associated petroleum gas is much higher.
Coal

Multicomponent mixture of various compounds of carbon, hydrogen, oxygen, nitrogen and sulfur. Also, coal contains a significant amount of inorganic substances, whose share is significantly higher than in oil.

Oil refining

Oil is a multicomponent mixture of various substances, mainly hydrocarbons. These components differ from each other in boiling points. In this regard, if oil is heated, then the lightest-boiling components will first evaporate from it, then compounds with a higher boiling point, etc. Based on this phenomenon primary oil refining , consisting in distillation (rectification) oil. This process is called primary, since it is assumed that during its course chemical transformations of substances do not occur, and oil is only separated into fractions with different boiling points. Below is a schematic diagram of a distillation column with brief description the distillation process itself:

Before the rectification process, oil is prepared in a special way, namely, it is removed from impurity water with salts dissolved in it and from solid mechanical impurities. The oil prepared in this way enters the tubular furnace, where it is heated to a high temperature (320-350 o C). After being heated in a tube furnace, the high temperature oil enters the lower part distillation column, where the evaporation of individual fractions and the rise of their vapors up the distillation column. The higher the section of the distillation column is, the lower its temperature. Thus, the following fractions are taken at different heights:

1) distillation gases (taken from the very top of the column, and therefore their boiling point does not exceed 40 ° C);

2) gasoline fraction (boiling point from 35 to 200 o C);

3) naphtha fraction (boiling points from 150 to 250 o C);

4) kerosene fraction (boiling points from 190 to 300 o C);

5) diesel fraction (boiling point from 200 to 300 o C);

6) fuel oil (boiling point over 350 o C).

It should be noted that the average fractions isolated during the rectification of oil do not meet the standards for fuel quality. In addition, as a result of oil distillation, a considerable amount of fuel oil is formed - far from being the most demanded product. In this regard, after the primary processing of oil, the task is to increase the yield of more expensive, in particular, gasoline fractions, as well as to improve the quality of these fractions. These tasks are solved using various processes. oil refining , such as cracking Andreforming .

It should be noted that the number of processes used in recycling oil, much more, and we touch on only some of the main ones. Let's now understand what is the meaning of these processes.

Cracking (thermal or catalytic)

This process is designed to increase the yield of the gasoline fraction. For this purpose, heavy fractions, such as fuel oil, are subjected to strong heating, most often in the presence of a catalyst. As a result of this action, long-chain molecules that are part of the heavy fractions are torn and hydrocarbons with a lower molecular weight are formed. In fact, this leads to an additional yield of a more valuable gasoline fraction than the original fuel oil. The chemical essence of this process is reflected by the equation:

Reforming

This process performs the task of improving the quality of the gasoline fraction, in particular, increasing its knock resistance (octane number). It is this characteristic of gasolines that is indicated at gas stations (92nd, 95th, 98th gasoline, etc.).

As a result of the reforming process, the proportion of aromatic hydrocarbons in the gasoline fraction increases, which among other hydrocarbons has one of the highest octane numbers. Such an increase in the proportion of aromatic hydrocarbons is achieved mainly as a result of the dehydrocyclization reactions occurring during the reforming process. For example, when heated sufficiently n-hexane in the presence of a platinum catalyst, it turns into benzene, and n-heptane in a similar way - into toluene:

Coal processing

The main method of coal processing is coking . Coal coking called the process in which coal is heated without access to air. At the same time, as a result of such heating, four main products are isolated from coal:

1) coke

A solid substance that is almost pure carbon.

2) Coal tar

Contains a large number of various predominantly aromatic compounds such as benzene homologues, phenols, aromatic alcohols, naphthalene, naphthalene homologues, etc.;

3) Ammonia water

Despite its name, this fraction, in addition to ammonia and water, also contains phenol, hydrogen sulfide and some other compounds.

4) coke oven gas

The main components of coke oven gas are hydrogen, methane, carbon dioxide, nitrogen, ethylene, etc.

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), about 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 impurities of nitrogen, 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 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. 4.

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: a basic level of/ 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?

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 weight of 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). This is one of the best views 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 it is 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 motor fuel, A 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 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 cracking gasoline has more high 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 last years petroleum hydrocarbons are 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.

The main natural sources of hydrocarbons are oil, gas, coal. Most of the substances of organic chemistry are isolated from them. More about this class of organic substances are discussed below.

Composition of minerals

Hydrocarbons are the most extensive class of organic substances. These include acyclic (linear) and cyclic classes of compounds. Allocate saturated (limit) and unsaturated (unsaturated) hydrocarbons.

The saturated hydrocarbons include compounds with single bonds:

  • alkanes- line connections;
  • cycloalkanes- cyclic substances.

Unsaturated hydrocarbons include substances with multiple bonds:

  • alkenes- contain one double bond;
  • alkynes- contain one triple bond;
  • alkadienes- includes two double bonds.

Separately, a class of arenes or aromatic hydrocarbons containing a benzene ring is distinguished.

Rice. 1. Classification of hydrocarbons.

Gaseous and liquid hydrocarbons are isolated from minerals. The table describes the natural sources of hydrocarbons in more detail.

Source

Kinds

Alkanes, cycloalkanes, arenes, oxygen, nitrogen, sulfur compounds
  • natural - a mixture of gases found in nature;
  • associated - a gaseous mixture dissolved in oil or located above it

Methane with impurities (not more than 5%): propane, butane, carbon dioxide, nitrogen, hydrogen sulfide, water vapor. Natural gas contains more methane than associated gas
  • anthracite - includes 95% carbon;
  • stone - contains 99% carbon;
  • brown - 72% carbon

Carbon, hydrogen, sulfur, nitrogen, oxygen, hydrocarbons

More than 600 billion m 3 of gas, 500 million tons of oil, and 300 million tons of coal are produced annually in Russia.

Recycling

Minerals are used in a processed form. Hard coal is calcined without access to oxygen (coking process) in order to isolate several fractions:

  • coke oven gas- a mixture of methane, carbon oxides (II) and (IV), ammonia, nitrogen;
  • coal tar- a mixture of benzene, its homologues, phenol, arenes, heterocyclic compounds;
  • ammonia water- a mixture of ammonia, phenol, hydrogen sulfide;
  • coke- final product coking, containing pure carbon.

Rice. 2. Coking.

One of the leading branches of the world industry is oil refining. Oil extracted from the bowels of the earth is called crude. It is being processed. First, mechanical purification from impurities is carried out, then the purified oil is distilled to obtain various fractions. The table describes the main oil fractions.

Fraction

Compound

What do they get

Gaseous alkanes from methane to butane

Petrol

Alkanes from pentane (C 5 H 12) to undecane (C 11 H 24)

Gasoline, ethers

Naphtha

Alkanes from octane (C 8 H 18) to tetradecane (C 14 H 30)

Naphtha (heavy gasoline)

Kerosene

Diesel

Alkanes from tridecane (C 13 H 28) to nonadecane (C 19 H 36)

Alkanes from pentadecane (C 15 H 32) to pentacontane (C 50 H 102)

Lubricating oils, petroleum jelly, bitumen, paraffin, tar

Rice. 3. Oil distillation.

Hydrocarbons are used to produce plastics, fibers, medicines. Methane and propane are used as domestic fuels. Coke is used in the production of iron and steel. Nitric acid, ammonia, fertilizers are produced from ammonia water. Tar is used in construction.

What have we learned?

From the topic of the lesson, we learned from which natural sources hydrocarbons are isolated. Oil, coal, natural and associated gases are used as raw materials for organic compounds. Minerals are purified and divided into fractions, from which substances suitable for production or direct use are obtained. Liquid fuels and oils are produced from oil. Gases contain methane, propane, butane used as domestic fuel. From coal, liquid and solid raw materials are isolated for the production of alloys, fertilizers, and medicines.

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