Natural gas: composition, use as a fuel. Natural sources of hydrocarbons. Oil refining Natural sources of hard coal

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

Oil

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

Coal

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

Coal coking

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 by rectification method

The 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).

The main 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, alkylation reactions.

Products: mixture of low-boiling hydrocarbons (fuel, feedstock 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

Lesson Objectives:

Training:

• To develop the cognitive activity of students.
• To acquaint students with natural sources of hydrocarbons: oil, natural gas, coal, their composition and processing methods.
• To study the main deposits of these resources on a global scale and in Russia.
• Show their importance in the national economy.
• Consider environmental protection issues.

Educational:

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

Developing:

• Develop attention, observation, the ability to listen and draw conclusions.

Pedagogical methods and techniques:

• Perceptive approach.
• Gnostic approach.
• cybernetic approach.

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

During the classes

I. Organizational moment.

I introduce the purpose and objectives of this lesson.

II. Main part.

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

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

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

I demonstrate samples of fractions from the collection (demonstration is accompanied by an explanation).

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

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

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

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

Students compare thermal and catalytic cracking. (Slide number 16)

Thermal cracking.

The splitting of hydrocarbon molecules proceeds at a higher temperature (470-5500 C). The process proceeds slowly, hydrocarbons with an unbranched chain of carbon atoms are formed. In gasoline obtained as a result of thermal cracking, along with saturated hydrocarbons, there are many unsaturated hydrocarbons. Therefore, this gasoline has a greater knock resistance than straight-run gasoline. Thermal cracking gasoline contains many unsaturated hydrocarbons, which are easily oxidized and polymerized. Therefore, this gasoline is less stable during storage. When it burns, various parts of the engine can become clogged.

catalytic cracking.

The splitting of hydrocarbon molecules proceeds in the presence of catalysts and at a lower temperature (450-5000 C). The focus is on petrol. They try to get more and necessarily better quality. Catalytic cracking appeared precisely as a result of the long-term, stubborn struggle of oilmen to improve the quality of gasoline. Compared to thermal cracking, the process proceeds much faster; in this case, not only the splitting of hydrocarbon molecules occurs, but also their isomerization, i.e. hydrocarbons with a branched chain of carbon atoms are formed. Compared to thermally cracked gasoline, catalytic cracked gasoline has even greater knock resistance.

Coal. (I introduce students to the origin of coal, the main reserves, mining, physical properties, processed products).

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

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

Mining:(I use the MarGTU electronic textbook, where they talk about coal mining).

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

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

III. Generalization.

In the generalizing part of the lesson, using the Turning Point program, I made a test. The students were armed with remotes. When a question appears on the screen, by pressing the corresponding button, they choose the correct answer.

1. The main components of natural gas are:

• Ethane;
• Propane;
• Methane;
• Butane.

2. What oil distillation fraction contains from 4 to 9 carbon atoms in a molecule?

• Naphtha;
• gas oil;
• Petrol;
• Kerosene.

3. What is the meaning of heavy oil cracking?

• Getting methane;
• Obtaining gasoline fractions with high detonation resistance;
• Obtaining synthesis gas;
• Obtaining hydrogen.

4. Which process does not apply to oil refining?

• Coking;
• Fractional distillation;
• catalytic cracking;
• Thermal cracking.

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

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

6. From methane forming natural gas, get:

• synthesis gas;
• Ethylene;
• Acetylene;
• Butadiene.

7. What features distinguish catalytic cracked gasoline from straight-run gasoline?

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

The test result is immediately visible on the screen.

Homework:§ 10, exercise 1 - 8

Literature:

1. L.Yu.Alikberova "Entertaining chemistry" - M.: "AST-Press", 1999.
2. O.S.Gabrielyan, I.G.Ostroumov “Desk book of a chemistry teacher Grade 10” - M .: “Blik and K”, 2001.
3. O.S.Gabrielyan, F.N.Maskaev, S.Yu.Ponomarev, V.I.Terenin "Chemistry Grade 10".

NATURAL SOURCES OF HYDROCARBONS

Hydrocarbons are all so different -
Liquid, solid, and gaseous.
Why are there so many of them in nature?
It's insatiable carbon.

Indeed, this element, like no other, is “insatiable”: it strives to form chains, straight and branched, then rings, then grids from a multitude of its atoms. Hence the many compounds of carbon and hydrogen atoms.

Hydrocarbons are both natural gas - methane, and another household combustible gas, which is filled with cylinders - propane C 3 H 8. Hydrocarbons are oil, gasoline, and kerosene. And also - an organic solvent C 6 H 6, paraffin, from which New Year's candles are made, petroleum jelly from a pharmacy, and even a plastic bag for food packaging ...

The most important natural sources of hydrocarbons are minerals - coal, oil, gas.

COAL

More known around the world 36 thousand coal basins and deposits, which together occupy 15% territories of the globe. Coal fields can stretch for thousands of kilometers. In total, the general geological reserves of coal on the globe are 5 trillion 500 billion tons, including explored deposits - 1 trillion 750 billion tons.

There are three main types of fossil coals. When burning brown coal, anthracite, the flame is invisible, the combustion is smokeless, and coal makes a loud crack when burning.

Anthraciteis the oldest fossil coal. Differs in the big density and gloss. Contains up to 95% carbon.

Coal- contains up to 99% carbon. Of all fossil coals, it is the most widely used.

Brown coal- contains up to 72% carbon. Has a brown color. As the youngest fossil coal, it often retains traces of the structure of the tree from which it was formed. Differs in high hygroscopicity and high ash content ( from 7% to 38%), therefore, it is used only as a local fuel and as a raw material for chemical processing. In particular, valuable types of liquid fuels are obtained by hydrogenation: gasoline and kerosene.

Carbon is the main constituent of coal 99% ), brown coal ( up to 72%). The origin of the name carbon, i.e., “bearing coal”. Similarly, the Latin name "carboneum" at the base contains the root carbo-coal.

Like oil, coal contains a large amount of organic matter. In addition to organic substances, it also includes inorganic substances, such as 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 1000 0 C, the following is formed:

coke oven gas- it consists of hydrogen, methane, carbon monoxide and carbon dioxide, impurities of ammonia, nitrogen and other gases.

Coal tar - contains several hundred different organic substances, including benzene and its homologues, phenol and aromatic alcohols, naphthalene and various heterocyclic compounds.

Top-tar or ammonia water - containing, as the name implies, dissolved ammonia, as well as phenol, hydrogen sulfide and other substances.

Coke– solid coking residue, practically 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. What is the geography of distribution of this mineral?

The main part of coal resources falls on the northern hemisphere - Asia, North America, Eurasia. What countries stand out in terms of reserves and coal production?

China, USA, India, Australia, Russia.

Countries are the main exporters of coal.

USA, Australia, Russia, South Africa.

main import centers.

Japan, Overseas Europe.

It is a very environmentally dirty fuel. Explosions and fires of methane occur during coal mining, and certain environmental problems arise.

Environmental pollution - this is any undesirable change in the state of this environment as a result of human activities. This also happens in mining. Imagine a situation in a coal mining area. Together with coal, a huge amount of waste rock rises to the surface, which, as unnecessary, is simply sent to dumps. Gradually formed waste heaps- huge, tens of meters high, cone-shaped mountains of waste rock, which distort the appearance of the natural landscape. And will all the coal raised to the surface be necessarily exported to the consumer? Of course not. After all, the process is not hermetic. A huge amount of coal dust settles on the surface of the earth. As a result, the composition of soils and groundwater changes, which will inevitably affect the flora and fauna of the region.

Coal contains radioactive carbon - C, but after the fuel is burned, the hazardous substance, along with smoke, enters the air, water, soil, and is baked into slag or ash, which is used to produce building materials. As a result, in residential buildings, walls and ceilings “glow” and pose a threat to human health.

OIL

Oil has been known to mankind since ancient times. On the banks of the Euphrates, it was mined

6-7 thousand years BC uh . It was used to illuminate dwellings, to prepare mortars, as medicines and ointments, and for embalming. Oil in the ancient world was a formidable weapon: fiery rivers poured on the heads of those who stormed the fortress walls, burning arrows dipped in oil flew to the besieged cities. Oil was an integral part of the incendiary agent that went down in history under the name "Greek fire" In the Middle Ages, it was mainly used for street lighting.

More than 600 oil and gas basins have been explored, 450 are being developed , and the total number of oil fields reaches 50 thousand.

Distinguish between light and heavy oil. Light oil is extracted from the subsoil by pumps or by the fountain method. Mostly gasoline and kerosene are made from such oil. Heavy grades of oil are sometimes extracted even by the mine method (in the Komi Republic), and bitumen, fuel oil, and various oils are prepared from it.

Oil is the most versatile fuel, high-calorie. Its extraction is relatively simple and cheap, because when extracting oil, there is no need to lower people underground. Transporting oil through pipelines is not a big problem. The main disadvantage of this type of fuel is the low availability of resources (about 50 years ) . General geological reserves are equal to 500 billion tons, including explored 140 billion tons .

IN 2007 Russian scientists proved to the world community that the underwater ridges of Lomonosov and Mendeleev, which are located in the Arctic Ocean, are a shelf zone of the mainland, and therefore belong to the Russian Federation. The chemistry teacher will tell about the composition of oil, its properties.

Oil is a "bundle of energy". With only 1 ml of it, you can heat a whole bucket of water by one degree, and in order to boil a bucket samovar, you need less than half a glass of oil. In terms of energy concentration per unit volume, oil ranks first among natural substances. Even radioactive ores cannot compete with it in this regard, since the content of radioactive substances in them is so small that 1mg can be extracted. nuclear fuel must be processed tons of rocks.

Oil is not only the basis of the fuel and energy complex of any state.

Here, the famous words of D. I. Mendeleev are in place “burning oil is the same as heating a furnace banknotes". Each drop of oil contains more than 900 various chemical compounds, more than half of the chemical elements of the Periodic Table. This is truly a miracle of nature, the basis of the petrochemical industry. Approximately 90% of all oil produced is used as fuel. In spite of “ own 10%” , petrochemical synthesis provides many thousands of organic compounds that satisfy the urgent needs of modern society. No wonder people respectfully call oil “black gold”, “the blood of the Earth”.

Oil is an oily dark brown liquid with a reddish or greenish tint, sometimes black, red, blue or light and even transparent with a characteristic pungent odor. Sometimes oil is white or colorless, like water (for example, in the Surukhanskoye field in Azerbaijan, in some fields in Algeria).

The composition of oil is not the same. But all of them usually contain three types of hydrocarbons - alkanes (mainly normal structure), cycloalkanes and aromatic hydrocarbons. The ratio of these hydrocarbons in the oil of different fields is different: for example, Mangyshlak oil is rich in alkanes, and oil in the Baku region is rich in cycloalkanes.

The main oil reserves are in the northern hemisphere. Total 75 countries of the world produce oil, but 90% of its production falls on the share of only 10 countries. About ? world oil reserves are in developing countries. (The teacher calls and shows on the map).

Main producing countries:

Saudi Arabia, USA, Russia, Iran, Mexico.

At the same time more 4/5 oil consumption falls on the share of economically developed countries, which are the main importing countries:

Japan, Overseas Europe, USA.

Oil in its raw form is not used anywhere, but refined products are used.

Oil refining

A modern plant consists of an oil heating furnace and a distillation column where the oil is separated into factions - individual mixtures of hydrocarbons according to their boiling points: gasoline, naphtha, kerosene. The furnace has a long tube coiled into a coil. The furnace is heated by the combustion products of fuel oil or gas. Oil is continuously supplied to the coil: there it is heated to 320 - 350 0 C in the form of a mixture of liquid and vapor and enters the distillation column. The distillation column is a steel cylindrical apparatus with a height of about 40m. It has inside several dozen horizontal partitions with holes - the so-called plates. Oil vapors, entering the column, rise up and pass through the holes in the plates. As they gradually cool as they move upwards, they partially liquefy. Less volatile hydrocarbons are liquefied already on the first plates, forming a gas oil fraction; more volatile hydrocarbons are collected above and form a kerosene fraction; even higher - naphtha fraction. The most volatile hydrocarbons leave the column as vapors and, after condensation, form gasoline. Part of the gasoline is fed back to the column for "irrigation", which contributes to a better mode of operation. (Entry in a notebook). Gasoline - contains hydrocarbons C5 - C11, boiling in the range from 40 0 ​​C to 200 0 C; naphtha - contains hydrocarbons C8 - C14 with a boiling point of 120 0 C to 240 0 C; kerosene - contains hydrocarbons C12 - C18, boiling at a temperature of 180 0 C to 300 0 C; gas oil - contains hydrocarbons C13 - C15, distilled off at a temperature of 230 0 C to 360 0 C; lubricating oils - C16 - C28, boil at a temperature of 350 0 C and above.

After distillation of light products from oil, a viscous black liquid remains - fuel oil. It is a valuable mixture of hydrocarbons. Lubricating oils are obtained from fuel oil by additional distillation. The non-distilling part of fuel oil is called tar, which is used in construction and when paving roads. (Demonstration of a video fragment). The most valuable fraction of direct distillation of oil is gasoline. However, the yield of this fraction does not exceed 17-20% by weight of crude oil. The problem arises: how to meet the ever-increasing needs of society in automotive and aviation fuel? The solution was found at the end of the 19th century by a Russian engineer Vladimir Grigorievich Shukhov. IN 1891 year, he first carried out an industrial cracking kerosene fraction of oil, which made it possible to increase the yield of gasoline to 65-70% (calculated as crude oil). Only for the development of the process of thermal cracking of petroleum products, grateful mankind inscribed the name of this unique person in the history of civilization with golden letters.

The products obtained as a result of oil rectification are subjected to chemical processing, which includes a number of complex processes, one of them is the cracking of petroleum products (from the English "Cracking" - splitting). There are several types of cracking: thermal, catalytic, high pressure cracking, reduction. Thermal cracking consists in the splitting of hydrocarbon molecules with a long chain into shorter ones under the influence of high temperature (470-550 0 C). In the process of this splitting, along with alkanes, alkenes are formed:

Currently, catalytic cracking is the most common. It is carried out at a temperature of 450-500 0 C, but at a higher speed and allows you to get higher quality gasoline. Under the conditions of catalytic cracking, along with cleavage reactions, isomerization reactions take place, that is, the transformation of hydrocarbons of a normal structure into branched hydrocarbons.

Isomerization affects the quality of gasoline, since the presence of branched hydrocarbons greatly increases its octane number. Cracking is referred to the so-called secondary processes of oil refining. A number of other catalytic processes, such as reforming, are also classified as secondary. Reforming- this is the aromatization of gasolines by heating them in the presence of a catalyst, for example, platinum. Under these conditions, alkanes and cycloalkanes are converted into aromatic hydrocarbons, as a result of which the octane number of gasoline also increases significantly.

Ecology and oilfield

For petrochemical production, the problem of the environment is especially relevant. Oil production is associated with energy costs and environmental pollution. A dangerous source of pollution of the oceans is offshore oil production, and the oceans are also polluted during the transportation of oil. Each of us has seen on TV the consequences of oil tanker accidents. Black, oil-covered shores, black surf, choking dolphins, Birds whose wings are covered in viscous oil, people in protective suits collecting oil with shovels and buckets. I would like to cite the data of a serious environmental disaster that occurred in the Kerch Strait in November 2007. 2,000 tons of oil products and about 7,000 tons of sulfur got into the water. The Tuzla Spit, which is located at the junction of the Black and Azov Seas, and the Chushka Spit suffered the most because of the disaster. After the accident, fuel oil settled to the bottom, which killed a small shell-heart-shaped, the main food of the inhabitants of the sea. It will take 10 years to restore the ecosystem. More than 15 thousand birds died. A liter of oil, having fallen into the water, spreads over its surface in spots of 100 sq.m. The oil film, although very thin, forms an insurmountable barrier to the path of oxygen from the atmosphere to the water column. As a result, the oxygen regime and the ocean are disturbed. "suffocate". Plankton, which is the backbone of the ocean food chain, is dying. Currently, about 20% of the area of ​​the World Ocean is covered with oil spills, and the area affected by oil pollution is growing. In addition to the fact that the World Ocean is covered with an oil film, we can also observe it on land. For example, in the oil fields of Western Siberia, more oil is spilled per year than a tanker can hold - up to 20 million tons. About half of this oil ends up on the ground as a result of accidents, the rest is “planned” fountains and leaks during well startups, exploratory drilling, and pipeline repairs. The largest area of ​​oil-contaminated land, according to the Committee for the Environment of the Yamalo-Nenets Autonomous Okrug, falls on the Purovsky District.

NATURAL AND ASSOCIATED PETROLEUM GAS

Natural gas contains hydrocarbons with a low molecular weight, the main components are methane. Its content in the gas of various fields ranges from 80% to 97%. In addition to methane - ethane, propane, butane. Inorganic: nitrogen - 2%; CO2; H2O; H2S, noble gases. When natural gas is burned, a lot of heat is released.

In terms of its properties, natural gas as a fuel surpasses even oil, it is more caloric. This is the youngest branch of the fuel industry. Gas is even easier to extract and transport. It is the most economical of all fuels. True, there are also disadvantages: the complex intercontinental transportation of gas. Tankers - methane manure, transporting gas in a liquefied state, are extremely complex and expensive structures.

It is used as: effective fuel, raw material in the chemical industry, in the production of acetylene, ethylene, hydrogen, soot, plastics, acetic acid, dyes, medicines, etc. production. Petroleum gas contains less methane, but more propane, butane and other higher hydrocarbons. Where is the gas produced?

More than 70 countries of the world have commercial gas reserves. Moreover, as in the case of oil, developing countries have very large reserves. But gas production is carried out mainly by developed countries. They have opportunities to use it or a way to sell gas to other countries that are on the same continent with them. International gas trade is less active than oil trade. About 15% of the world's produced gas enters the international market. Almost 2/3 of world gas production is provided by Russia and the USA. Undoubtedly, the leading gas production region not only in our country, but also in the world is the Yamalo-Nenets Autonomous Okrug, where this industry has been developing for 30 years. Our city Novy Urengoy is rightfully recognized as the gas capital. The largest deposits include Urengoyskoye, Yamburgskoye, Medvezhye, Zapolyarnoye. The Urengoy field is included in the Guinness Book of Records. The reserves and production of the deposit are unique. Explored reserves exceed 10 trillion. m 3 , 6 trln. m 3. In 2008 JSC "Gazprom" plans to produce 598 billion m 3 of "blue gold" at the Urengoy field.

Gas and ecology

The imperfection of the technology of oil and gas production, their transportation causes the constant burning of the volume of gas in the heat units of compressor stations and in flares. Compressor stations account for about 30% of these emissions. About 450,000 tons of natural and associated gas are burned annually at flare installations, while more than 60,000 tons of pollutants enter the atmosphere.

Oil, gas, coal are valuable raw materials for the chemical industry. In the near future, they will find a replacement in the fuel and energy complex of our country. Currently, scientists are looking for ways to use solar and wind energy, nuclear fuel in order to completely replace oil. Hydrogen is the most promising fuel of the future. Reducing the use of oil in thermal power engineering is the way not only to its more rational use, but also to the preservation of this raw material for future generations. Hydrocarbon raw materials should be used only in the processing industry to obtain a variety of products. Unfortunately, the situation is not changing yet, and up to 94% of the produced oil is used as fuel. D. I. Mendeleev wisely said: “Burning oil is the same as heating the furnace with banknotes.”

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

Oil. Oil refining

Many of the organic substances you deal with in everyday life—plastics, paints, detergents, drugs, 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 minerals. 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 (Figure 29.1). It is a homogeneous mixture of several hundred substances - mostly saturated hydrocarbons with the number of carbon atoms in the molecule from 1 to 40.

Both physical and chemical methods are used to process this mixture. 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 takes place in a distillation column with significant heating (Fig. 29.2). The fractions with the highest boiling points, which decompose at high temperatures, are 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 boilers

Ukraine is quite rich in oil reserves. The main deposits are concentrated in three oil and gas regions: eastern (Sumy, Poltava, Chernihiv and Kharkiv 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). The annual oil production in Ukraine is about 2 million tons, while the demand is 16 million tons, so, unfortunately, Ukraine is still forced to import significant volumes of oil.

Chemical processing of petroleum products

Some products of oil distillation can be used immediately without further processing - these are gasoline and kerosene, but they make up only 20-30% of oil. In addition, after distillation, gasoline is of poor quality (with a low octane number, that is, when compressed in the engine, it explodes and does not burn out). An engine running on such fuel makes a characteristic knock and quickly fails. To improve the quality of gasoline and increase its yield, oil is subjected to chemical processing.

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

This process increases the yield of gasoline and kerosene. Such gasoline is sometimes referred to as cracked gasoline.

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

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

Natural gas

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

A large amount of natural gas is 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 obtained by heating methane with steam:

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

When passed over a cobalt catalyst, 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.

Hard coal is also used as a fuel, however, there are big environmental problems. Firstly, coal contains non-combustible impurities, which turn into slags during the combustion of fuel; secondly, coal contains small amounts of Sulfur and Nitrogen compounds, the combustion of which produces oxides that pollute the atmosphere. In terms of coal reserves, Ukraine occupies one of the first places in the world. On the territory equal to 0.4% of the world, about 5% of the world's reserves of energy raw materials are concentrated in Ukraine, 95% of which are hard 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 hard 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 use, these natural resources must be processed to isolate individual substances or mixtures.

test questions

334. Name the main natural sources of hydrocarbons.

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

336. Into what fractions is oil separated during distillation? Describe their application. What is the most valuable product of oil refining for modern society?

337. What is the difference between the most important oil products in terms of chemical composition?

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

339. What main products are extracted by coking coal?

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

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

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

Tasks for mastering the material

343. During the cracking of 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 the fundamental difference between oil cracking and rectification?

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

346. Analyze fig. 29.2 and describe how oil is distilled.

347. Make equations for the reactions of obtaining 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(II) oxide and hydrogen.

349. When gasoline is completely burned, 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(II) oxide and nitrogen(N) oxide. Explain what chemical reactions they were formed as a result of.

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 upon ignition? When calculating, assume that the air contains 20% oxygen (by volume).

352. Gasoline sold in warm climates contains higher molecular weight hydrocarbons than gasoline sold in cold climates. Suggest why 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 banknotes.” How do you understand this statement? Suggest ways of rational use of natural sources of hydrocarbons.

354*. In additional sources, find information about materials and substances that are raw materials for oil, natural gas or coal. Can they be made without using natural sources of hydrocarbons? Can humanity refuse to use these materials? Justify the answer.

355*. Using the knowledge gained in geography lessons in grades 8 and 9, describe the current and prospective basins and areas of coal, oil, natural gas production in Ukraine. Whether the location of the enterprises for the processing of these sources of hydrocarbons is coordinated with their deposits.

This is textbook material.