Preparation of aromatic hydrocarbons. Natural springs. Natural sources of hydrocarbons: general characteristics and use Natural sources of hydrocarbons and their practical use
Hydrocarbons are of great economic importance, since they serve as the most important type of raw material for the production of almost all products of the modern organic synthesis industry and are widely used for energy purposes. They seem to accumulate solar heat and energy, which are 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 |
| homogeneous composition | homogeneous composition | mixture of substances | mixture of substances |
| a dark-colored rock with a high content of flammable substances resulting from the burial of accumulations of various plants in sedimentary strata | accumulation of half-rotted plant matter accumulated at the bottom of swamps and overgrown lakes | natural flammable oily liquid, consisting 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 when burning 1 kg of fuel | |||
| 7 000 - 9 000 | 500 - 2 000 | 10000 - 15000 | ? |
Coal.
Coal has always been a promising raw material for producing energy and many chemical products.
The first major consumer of coal since the 19th century was transport, then coal began to be used for the production of electricity, metallurgical coke, the production of various products through chemical processing, carbon-graphite structural materials, plastics, rock wax, synthetic, liquid and gaseous high-calorie fuels, high-nitrous acids for the production fertilizers
Coal is a complex mixture of high-molecular compounds, which include the following elements: C, H, N, O, S. Coal, like oil, contains a large number of various organic substances, as well as inorganic substances, such as water, ammonia, hydrogen sulfide and of course carbon itself - coal.
Coal processing occurs in three main directions: coking, hydrogenation and incomplete combustion. One of the main methods of processing coal 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 complex chemical transformations, resulting in the formation of coke and volatile products:
1. coke oven gas (hydrogen, methane, carbon monoxide and carbon dioxide, admixtures 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. tar, or ammonia, water (dissolved ammonia, as well as phenol, hydrogen sulfide and other substances);
4. coke (solid coking residue, almost pure carbon).
The cooled coke is sent to metallurgical plants.
When volatile products (coke oven gas) are cooled, coal tar and ammonia water condense.
By passing non-condensed products (ammonia, benzene, hydrogen, methane, CO 2, nitrogen, ethylene, etc.) through a solution of sulfuric acid, ammonium sulfate is released, which is used as a mineral fertilizer. Benzene is absorbed into the solvent and distilled from the solution. After this, the coke oven gas is used as 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 the production of a number of organic substances. If you remove products boiling at 350°C from the resin, what remains is a solid mass - pitch. It is used to make 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. This produces a mixture of liquid hydrocarbons, which can be used as motor fuel. Production of liquid fuel from coal. Liquid synthetic fuel is high-octane gasoline, diesel and boiler fuel. To obtain liquid fuel from coal, it is necessary to increase its hydrogen content through hydrogenation. Hydrogenation is carried out using multiple circulation, which allows you to convert the entire organic mass of coal into liquid and gases. The advantage of this method is the possibility of hydrogenating low-grade brown coal.
Coal gasification will make it possible to use low-quality brown and hard coal in thermal power plants without polluting the environment with sulfur compounds. This is the only method for producing concentrated carbon monoxide (carbon monoxide) CO. Incomplete combustion of coal produces carbon (II) monoxide. Using a catalyst (nickel, cobalt) at normal or increased pressure, gasoline containing saturated and unsaturated hydrocarbons can be obtained from hydrogen and CO:
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 binding material in the manufacture of roofing and waterproofing coatings (roofing felt, roofing felt, etc.).
In nature, hard coal is found in the following regions: Moscow Region, South Yakutsk Basin, Kuzbass, Donbass, Pechora Basin, Tunguska Basin, 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 petroleum compounds - mercaptans. It is they that give the gas a specific unpleasant odor, and when burned, lead to the formation of toxic sulfur dioxide SO 2 .
Typically, the higher the molecular weight of a hydrocarbon, the less of it is found in natural gas. The composition of natural gas from different fields is not the same. Its average composition in percentage by volume is as follows:
| CH 4 | C 2 H 6 | C 3 H 8 | C 4 H 10 | N 2 and other gases |
| 75-98 | 0,5 - 4 | 0,2 – 1,5 | 0,1 – 1 | 1-12 |
Methane is formed during anaerobic (without access to air) fermentation of plant and animal residues, therefore it is formed in bottom sediments and is called “swamp” gas.
Deposits of methane in hydrated crystalline form, the so-called methane hydrate discovered under a layer of permafrost and at great depths in the oceans. At low temperatures (−800ºC) and high pressures, methane molecules are located in the voids of the crystal lattice of water ice. In the ice voids of one cubic meter of methane hydrate, 164 cubic meters of gas are “canned.”
Chunks of methane hydrate look like dirty ice, but in air they burn with a yellow-blue flame. It is estimated that the planet stores between 10,000 and 15,000 gigatons of carbon in the form of methane hydrate (“giga” equals 1 billion). Such volumes are many times greater than all currently known natural gas reserves.
Natural gas is a 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 with the use of gas as an alternative fuel.
As a fuel, natural gas has great advantages over solid and liquid fuels. Its heat of combustion is much higher, when burned it does not leave ash, and the combustion products are much cleaner environmentally. Therefore, about 90% of the total volume of extracted natural gas is burned as fuel in thermal power plants and boiler houses, in thermal processes in industrial enterprises and in everyday life. About 10% of natural gas is used as a valuable raw material for the chemical industry: for the production of hydrogen, acetylene, soot, various plastics, and medicines. Methane, ethane, propane and butane are separated 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 Northern and Western Siberia, the Volga-Ural basin, the North Caucasus (Stavropol), the Komi Republic, the Astrakhan region, and the Barents Sea.
Natural sources of hydrocarbons are fossil fuels - oil and
gas, coal and peat. Crude oil and gas deposits arose 100-200 million years ago
back from the microscopic marine plants and animals that turned out to be
included in sedimentary rocks formed on the seabed, Unlike
This coal and peat began to form 340 million years ago from plants,
growing on land.
Natural gas and crude oil are commonly found with water in
oil-bearing layers located between rock layers (Fig. 2). Term
“natural gas” also applies to gases that are formed in natural
conditions resulting from coal decomposition. Natural gas and crude oil
are being developed on all continents, with the exception of Antarctica. The largest
Natural gas producers in the world are Russia, Algeria, Iran and
United States. The largest producers of crude oil are
Venezuela, Saudi Arabia, Kuwait and Iran.
Natural gas consists mainly of methane (Table 1).
Crude oil is an oily liquid whose color may
be very diverse - from dark brown or green to almost
colorless. It contains a large number of alkanes. Among them there are
straight alkanes, branched alkanes and cycloalkanes with number of atoms
carbon from five to 40. The industrial name of these cycloalkanes is nachta. IN
crude oil also contains approximately 10% aromatic
hydrocarbons, as well as small amounts of other compounds containing
sulfur, oxygen and nitrogen.
Table 1 Composition of natural gas
Coal is the oldest source of energy with which we are familiar
humanity. It is a mineral (Fig. 3), which was formed from
plant matter in the process of metamorphism. Metamorphic
are called rocks whose composition has undergone changes in conditions
high pressures as well as high temperatures. The product of the first stage in
the process of coal formation is peat, which is
decomposed organic matter. Coal is formed from peat after
it is covered with sedimentary rocks. These sedimentary rocks are called
overloaded. Overloaded sediment reduces the moisture content of the peat.
Three criteria are used in the classification of coals: purity (determined
relative carbon content in percent); type (defined
composition of the original plant matter); grade (depending on
degree of metamorphism).
Table 2 Carbon content of some fuels and their calorific value
ability
The lowest grade types of fossil coals are brown coal and
lignite (Table 2). They are closest to peat and are characterized relatively
characterized by lower moisture content and is widely used in
industry. The driest and hardest type of coal is anthracite. His
used for heating homes and cooking.
Recently, thanks to technological advances, it has become increasingly
economical gasification of coal. Coal gasification products include
carbon monoxide, carbon dioxide, hydrogen, methane and nitrogen. They are used in
as a gaseous fuel or as a raw material for the production of various
chemical products and fertilizers.
Coal, as outlined below, is an important source of raw material for the production of
aromatic compounds. Coal represents
is a complex mixture of chemicals that include carbon,
hydrogen and oxygen, as well as small amounts of nitrogen, sulfur and other impurities
elements. In addition, the composition of coal, depending on its type, includes
different amounts of moisture and different minerals.
Hydrocarbons occur naturally not only in fossil fuels, but also in
in some materials of biological origin. Natural rubber
is an example of a natural hydrocarbon polymer. rubber molecule
consists of thousands of structural units representing methyl buta-1,3-diene
(isoprene);
Natural rubber. Approximately 90% natural rubber, which
currently mined all over the world, obtained from Brazilian
rubber tree Hevea brasiliensis, cultivated mainly in
equatorial countries of Asia. The sap of this tree, which is latex
(colloidal aqueous solution of polymer), collected from cuts made with a knife on
bark Latex contains approximately 30% rubber. His tiny pieces
suspended in water. The juice is poured into aluminum containers, where acid is added,
causing the rubber to coagulate.
Many other natural compounds also contain isoprene structures.
fragments. For example, limonene contains two isoprene units. Limonene
is the main component of oils extracted from citrus peels,
such as lemons and oranges. This connection belongs to the class of connections
called terpenes. Terpenes contain 10 carbon atoms (C) in their molecules
10-compounds) and include two isoprene fragments connected to each other
each other sequentially (“head to tail”). Compounds with four isoprene
fragments (C 20 compounds) are called diterpenes, and with six
isoprene fragments - triterpenes (C 30 compounds). Squalene,
which is found in shark liver oil is a triterpene.
Tetraterpenes (C 40 compounds) contain eight isoprene
fragments. Tetraterpenes are found in pigments of vegetable and animal fats
origin. Their color is due to the presence of a long conjugate system
double bonds. For example, β-carotene is responsible for the characteristic orange color
carrot coloring.
Oil and coal processing technology
At the end of the 19th century. Under the influence of progress in the field of thermal power engineering, transport, engineering, military and a number of other industries, demand has increased immeasurably and an urgent need has arisen for new types of fuel and chemical products.
At this time, the oil refining industry was born and rapidly progressed. A huge impetus to the development of the oil refining industry was given by the invention and rapid spread of the internal combustion engine running on petroleum products. The technology for processing coal, which not only serves as one of the main types of fuel, but, what is especially noteworthy, became a necessary raw material for the chemical industry during the period under review, also developed intensively. A major role in this matter belonged to coke chemistry. Coke plants, which previously supplied coke to the iron and steel industry, turned into coke-chemical enterprises, which also produced a number of valuable chemical products: coke oven gas, crude benzene, coal tar and ammonia.
Based on the products of oil and coal processing, the production of synthetic organic substances and materials began to develop. They are widely used as raw materials and semi-finished products in various branches of the chemical industry.
Ticket#10
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 has been discovered on the planets of the solar system and their satellites.
Pure methane has no odor. However, the gas used in everyday life has a characteristic unpleasant odor. 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 - associated petroleum 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, necessary for metallurgy, coke oven gas and coal tar. 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 the 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.
The method of separating oil based on the different boiling points 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. Fundamentals of general chemistry. 10th grade: textbook for general education institutions: basic level / 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?
– 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-refined 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
