Oil refining. Natural sources of hydrocarbons

It should be noted that hydrocarbons are widespread in nature. Most organic substances are obtained from natural sources. In the process of synthesis organic compounds natural and associated gases, hard and brown coal, oil, peat, animal products and plant origin.

Natural springs hydrocarbons: natural gases.

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

Main structural component combustible natural gases are СН₄ (methane - 98%), С₂Н₆ (ethane - 4.5%), propane (С₃Н₈ - 1.7%), butane (С₄Н₁₀ - 0.8%), pentane (С₅Н₁₂ - 0.6% ). Related petroleum gas It 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 valuable fuel and raw materials for the organic synthesis industry. Gas is supplied to gas processing plants, where it can be processed (oil, low-temperature adsorption, condensation and rectification). It is divided into individual components, each of which is used for specific purposes. For example, from methane synthesis gas, which is the basic raw material for the production of other hydrocarbons, acetylene, methanol, methanal, chloroform.

Natural sources of hydrocarbons: oil.

Oil is a complex mixture that consists primarily 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 using petrochemical synthesis methods, more than 3000 different products are obtained, incl. ethylene, benzene, propylene, dichloroethane, vinyl chloride, styrene, ethanol, isopropanol, butylenes, various plastics, chemical fibers, dyes, detergents, medicines, explosives, etc.

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

Natural sources of hydrocarbons: xylem or wood.

Xylem - tissue higher plants, along 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 quantities pectin substances and mineral compounds (mainly calcium salts), lipids and essential oils. Wood is used as fuel and can be synthesized from methyl alcohol, acetate acid, cellulose, and other substances. Some types of wood are used to produce dyes (sandalwood, logwood), tannins (oak), resins and balsams (cedar, pine, spruce), and alkaloids (plants of the nightshade, poppy, ranunculaceae, and umbellaceae families). Some alkaloids are used as medicines(chitin, caffeine), herbicides (anabasine), insecticides (nicotine).

– consists (mainly) of methane and (in smaller quantities) its closest homologues - ethane, propane, butane, pentane, hexane, etc.; observed in associated petroleum gas, i.e. natural gas found in nature above oil or dissolved in it under pressure.

Oil

is an oily flammable liquid consisting of alkanes, cycloalkanes, arenes (predominant), as well as oxygen-, nitrogen- and sulfur-containing compounds.

Coal

– solid fuel mineral of organic origin. It contains little graphite and many complex cyclic compounds, including the elements C, H, O, N and S. Anthracite (almost anhydrous), coal (-4% moisture) and brown coal (50-60% moisture) are found. Using the coking method, coal is converted into hydrocarbons (gaseous, liquid and solid) and coke (fairly pure graphite).

Coking of coal

Heating coal without air access to 900-1050 ° C leads to its thermal decomposition with the formation of volatile products (coal tar, ammonia water and coke oven gas) and a solid residue - coke.

Main products: coke - 96-98% carbon; coke oven gas -60% hydrogen, 25% methane, 7% carbon monoxide (II), etc.

By-products: coal tar (benzene, toluene), ammonia (from coke oven gas), etc.

Oil refining using rectification method

Pre-purified oil is subjected to atmospheric (or vacuum) distillation into fractions with certain boiling point ranges in continuous distillation columns.

Main products: light and heavy gasoline, kerosene, gas oil, lubricating oils, fuel oil, tar.

Oil refining by catalytic cracking

Raw materials: high-boiling oil fractions (kerosene, gas oil, etc.)

Auxiliary materials: catalysts (modified aluminosilicates).

Basic chemical process: at a temperature of 500-600 °C and a pressure of 5·10 5 Pa, hydrocarbon molecules are split into smaller molecules, catalytic cracking is accompanied by aromatization, isomerization, and alkylation reactions.

Products: mixture of low-boiling hydrocarbons (fuels, raw materials for petrochemicals).

C 16. H 34 → C 8 H 18 + C 8 H 16
C 8 H 18 → C 4 H 10 + C 4 H 8
C 4 H 10 → C 2 H 6 + C 2 H 4

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 humanity is obtained from fossil natural organic compounds. You will learn about natural resources (natural gas, oil, coal), what happens to oil after its extraction.

Topic: Saturated 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 fuel reserves. There are large reserves of oil and natural gas in Western Siberia and the Urals. Coal is mined in the Kuznetsk, South Yakutsk basins and other regions.

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

In addition to methane, natural gas from various fields contains nitrogen, carbon dioxide, helium, hydrogen sulfide, as well as 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 access to air. Methane is constantly being formed as a result of the activity of microorganisms.

Methane discovered on planets solar system and their companions.

Pure methane has no odor. However, the gas used in everyday life has a characteristic bad smell. This is what special additives smell like - mercaptans. The smell of mercaptans allows you to detect a domestic gas leak in time. Mixtures of methane with air are explosive in a wide range of ratios - from 5 to 15% gas by volume. Therefore, if you smell gas in a room, you should not only light a fire, but also not use electrical switches. The slightest spark can cause an explosion.

Rice. 1. Oil from different fields

Oil- a thick liquid similar to oil. Its color ranges 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 classified as limiting, i.e. alkanes. Rice. 2.

Oil also contains organic compounds containing sulfur, oxygen, nitrogen. Oil contains water and inorganic impurities.

Gases that are released during its production are dissolved in oil - oil associated gases . These are methane, ethane, propane, butanes with admixtures 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 matter in oil shale.

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

Rice. 3. Construction of a coke oven

Natural gas and oil are the most important sources of raw materials for chemical industry. Oil as it is extracted, or “crude oil,” is difficult to use even as 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. Petroleum products

The fraction that distills from approximately 50 to 180 0 C is called gasoline.

Kerosene boils at temperatures of 180-300 0 C.

A thick black residue containing no volatile substances is called fuel oil.

There are also a number of intermediate fractions that boil 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 to produce lubricating oils and paraffin. Solid residue from fuel oil distillation - asphalt. It is used for the production of road surfaces.

Processing of associated petroleum gases is a separate industry and produces 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 humanity is obtained from fossil natural organic compounds. You learned about natural resources (natural gas, oil, coal), what happens to oil after its extraction.

Bibliography

1. Rudzitis G.E. Chemistry. Basics general chemistry. 10th grade: textbook for general education institutions: a basic level of/ G. E. Rudzitis, F.G. Feldman. - 14th edition. - M.: Education, 2012.

2. Chemistry. Grade 10. Profile level: academic. for general education institutions/ V.V. Eremin, N.E. Kuzmenko, V.V. Lunin et al. - M.: Bustard, 2008. - 463 p.

3. Chemistry. Grade 11. Profile level: academic. for general education institutions/ V.V. Eremin, N.E. Kuzmenko, V.V. Lunin et al. - M.: Bustard, 2010. - 462 p.

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

Homework

1. No. 3, 6 (p. 74) Rudzitis G.E., Feldman F.G. Chemistry: Organic chemistry. 10th grade: textbook for general education institutions: basic level / G. E. Rudzitis, F.G. Feldman. - 14th edition. - M.: Education, 2012.

2. How does associated petroleum gas differ from natural gas?

3. How is oil distilled?

Remember: distillation (distillation) is a method of separating a mixture of volatile liquids by gradual evaporation followed by condensation.

Oil. Oil distillation

Many of the organic substances you deal with in Everyday life,—plastics, paints, detergents, medicines, varnishes, solvents—are synthesized from hydrocarbons. There are three main sources of hydrocarbons in nature - oil, natural gas and coal.

Oil is one of the most important mineral resources. It is impossible to imagine our life without oil and its products. It is not for nothing that oil-rich countries play an important role in the global economy.

Oil is a dark, oily liquid found in the earth's crust (Fig. 29.1). It is a homogeneous mixture of several hundred substances - mainly saturated hydrocarbons with the number of carbon atoms in a molecule from 1 to 40.

To process this mixture, both physical and chemical methods are used. First, oil is separated into simple mixtures - fractions - by distillation (distillation or rectification), based on the fact that various substances in the composition of oil boil at different temperatures(Table 12). Distillation occurs in a distillation column under significant heating (Fig. 29.2). Factions with the most high temperatures boiling, decomposing at high temperature, distilled under reduced pressure.

Table 12. Oil distillation fractions

	Number of carbon atoms in molecules	Boiling point, °C	Application
		Over 200 o C
			Automotive fuel
			Fuel, raw materials for synthesis
			Aviation gasoline
			Diesel fuel
Heavy gas oil (fuel oil)			Fuel for thermal power plants
		Decomposes when heated, distilled under reduced pressure	Production of asphalt, bitumen, paraffin, lubricants, fuel for boiler houses

Ukraine is quite rich in oil reserves. The main fields are concentrated in three oil and gas regions: eastern (Sumy, Poltava, Chernihiv and Kharkov regions), western (Lviv and Ivano-Frankivsk regions) and southern (Black Sea region, shelves of the Azov and Black Seas). Oil reserves in Ukraine are estimated at about 2 billion tons, but a significant part of them is concentrated at great depths (5-7 km). Annual oil production in Ukraine is about 2 million tons with a demand of 16 million tons, so, unfortunately, Ukraine is still forced to import significant volumes of oil.

Chemical refining of petroleum products

Some petroleum distillation products can be used immediately, without further processing, such as gasoline and kerosene, but they make up only 20-30% of oil. In addition, after distillation, gasoline is of low quality (with a low octane number, i.e., when compressed in the engine, it explodes rather than burns). An engine running on such fuel makes a characteristic knocking noise and quickly fails. To improve the quality of gasoline and increase its yield, oil is subjected to chemical processing.

One of the most important ways chemical refining of oil - cracking (from the English to crack - to split, break, since during cracking the carbon chains are broken) (Fig. 29.3). When heated to 500 °C without air access in the presence of special catalysts, long alkane molecules are split into smaller ones. When cracking saturated hydrocarbons, a mixture of light saturated and unsaturated hydrocarbons is formed, for example:

Thanks to this process, the yield of gasoline and kerosene increases. This type of gasoline is sometimes called cracked gasoline.

One of the characteristics that determines the quality of gasoline is the octane number, which indicates the possibility of detonation (explosion) of the fuel-air mixture in the engine. The higher the octane number, the lower the likelihood of detonation, and therefore the higher the quality of gasoline. Heptane is unsuitable as motor fuel, it is more likely to detonate, while isooctane (2,2,4-trimethylpentane) has the opposite properties - it almost does not detonate in the engine. These two substances became the basis for the scale for determining the quality of gasoline - the octane number scale. On this scale, heptane received a value of 0, and isooctane - 100. According to this scale, gasoline with an octane rating of 95 has the same knocking properties as a mixture of 95% isooctane and 5% heptane.

Oil refining occurs at special enterprises - oil refineries. There they carry out both rectification of crude oil and chemical processing of the resulting petroleum products. There are six oil refineries in Ukraine: in Odessa, Kremenchug, Kherson, Lisichansk, Nadvornyansk and Drohobych. The total capacity of all Ukrainian oil refining enterprises exceeds 52 million tons per year.

Natural gas

The second most important source of hydrocarbons is natural gas, the main component of which is methane (93-99%). Natural gas is used primarily as an efficient fuel. When it burns, neither ash nor poisonous substances are formed. carbon monoxide, therefore natural gas is considered an environmentally friendly fuel.

Large quantities of natural gas are used by the chemical industry. Processing of natural gas is reduced mainly to the production of unsaturated hydrocarbons and synthesis gas. Ethylene and acetylene are formed by the elimination of hydrogen from lower alkanes:

Synthesis gas - a mixture of carbon(II) oxide and hydrogen - is produced by heating methane with water steam:

From this mixture, using different catalysts, oxygen-containing compounds are synthesized - methyl alcohol, acetic acid, etc.

When passed over a cobalt catalyst, the synthesis gas is converted into a mixture of alkanes, which is synthetic gasoline:

Coal

Another source of hydrocarbons is coal. In the chemical industry it is processed by coking - heating to 1000 ° C without air access (Fig. 29.5, p. 170). In this case, coke and coal tar are formed, the mass of which is only a few percent of the mass of coal. Coke is used as a reducing agent in metallurgy (for example, to obtain iron from its oxides).

Coal tar contains several hundred organic compounds, mainly aromatic hydrocarbons, which are obtained from it by distillation.

Coal is also used as a fuel, but this creates large ecological problems. Firstly, coal contains non-flammable impurities, which turn into slag during fuel combustion; secondly, coal contains small quantities compounds of Sulfur and Nitrogen, the combustion of which produces oxides that pollute the atmosphere. Ukraine ranks one of the first in the world in terms of coal reserves. On a territory equal to 0.4% of the world, Ukraine contains about 5% of the world's reserves of energy raw materials, 95% of which is coal (about 54 billion tons). In 2015, coal production amounted to 40 million tons, which is almost half as much as in 2011. Today there are 300 coal mines in Ukraine, and 40% of them produce coking coal (which can be processed into coke). Production is concentrated mainly in the Donetsk, Lugansk, Dnepropetrovsk and Volyn regions.

Linguistic task

In Greek, pyro means "fire" and lysis means "decomposition." Why do you think the terms “cracking” and “pyrolysis” are often used interchangeably?

Key idea

The main sources of hydrocarbons for industry are oil, coal and natural gas. For more effective application these natural resources must be processed to isolate individual substances or mixtures.

Control questions

334. Name the main natural sources of hydrocarbons.

335. What is the physical method of separating oil into fractions based on?

336. What fractions is oil divided into during distillation? Describe their use. Which petroleum product is the most valuable for modern society?

337. How do the most important petroleum products differ in chemical composition?

338. Using information from this and previous paragraphs, describe the use of natural gas in the chemical industry.

339. What are the main products produced by coking coal?

340. Why is coal heated during processing without air access?

341. Why is natural gas better than coal as a fuel?

342. What substances and materials are produced by processing coal and natural gas?

Assignments for mastering the material

343. In the process of cracking the hydrocarbon C 20 H 42, two products are formed with the same number of Carbon atoms in the molecules. Write an equation for the reaction.

344. What is it? fundamental difference cracking oil from rectification?

345. Why do you think that during direct distillation of oil it is not possible to process more than 20% of it into gasoline?

346. Analyze fig. 29.2 and describe how petroleum distillation occurs.

347. Write down equations for the reactions of producing ethylene and acetylene from natural gas components.

348. One of the components of gasoline is the hydrocarbon C 8 H 18. Write an equation for the reaction of its production from carbon(I) oxide and hydrogen.

349. When gasoline burns completely, carbon dioxide and water are formed in the engine. Write an equation for the combustion reaction of gasoline, assuming that it consists of hydrocarbons of the composition C 8 H 18.

350. Car exhaust gases contain toxic substances: carbon(N) oxide and nitrogen(^) oxide. Explain why chemical reactions they were formed.

351. How many times will the volume of the fuel-air mixture, consisting of 40 ml of octane vapor and 3 liters of air, increase when ignited? When making calculations, assume that the air contains 20% oxygen (by volume).

352. Gasoline sold in countries with warm climate, consists of hydrocarbons with a higher molecular weight than gasoline, which is sold in countries with cold climates. Guess why oil refiners do this.

353*. Oil contains so many valuable organic substances that D.I. Mendeleev said: “Burning oil in a furnace is almost the same as burning with banknotes.” How do you understand this statement? Suggest ways rational use natural sources of hydrocarbons.

354*. In additional sources, find information about materials and substances whose raw materials are oil, natural gas or coal. Can they be made without using natural sources of hydrocarbons? Is it possible for humanity to stop using these materials? Justify your answer.

355*. Using the knowledge gained in geography lessons in grades 8 and 9, describe the current and promising basins and areas of coal, oil, and natural gas production in Ukraine. Are the locations of processing plants for these hydrocarbon sources coordinated with their deposits?

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