Natural sources of hydrocarbons: gas, oil, coke. Their use as fuel and in chemical synthesis
The most important natural sources of hydrocarbons are oil , natural gas And coal . They form rich deposits in various regions of the Earth.
Previously mined natural products used exclusively as fuel. Currently, methods for their processing have been developed and are widely used, making it possible to isolate valuable hydrocarbons, which are used both as high-quality fuel and as raw materials for various organic syntheses. Processes natural sources of raw materials petrochemical industry . Let's look at the main processing methods natural hydrocarbons.
The most valuable source of natural raw materials is oil . It is an oily liquid of dark brown or black color with a characteristic odor, practically insoluble in water. Oil density is 0.73–0.97 g/cm3. Oil is a complex mixture of various liquid hydrocarbons in which gaseous and solid hydrocarbons are dissolved, and the composition of oil from different fields may differ. Alkanes, cycloalkanes, aromatic hydrocarbons, as well as oxygen-, sulfur- and nitrogen-containing organic compounds may be present in oil in varying proportions.
Crude oil is practically not used, but is processed.
Distinguish primary oil refining (distillation ), i.e. dividing it into fractions with different boiling points, and recycling (cracking ), during which the structure of hydrocarbons is changed
dovs included in its composition.
Primary oil refining is based on the fact that the higher the boiling point of hydrocarbons, the higher their molar mass. Oil contains compounds with boiling points from 30 to 550°C. As a result of distillation, oil is divided into fractions that boil at different temperatures and containing mixtures of hydrocarbons with different molar masses. These fractions have a variety of uses (see Table 10.2).
Table 10.2. Products primary processing oil.
| Fraction | Boiling point, °C | Compound | Application |
| Liquefied gas | <30 | Hydrocarbons C 3 -C 4 | Gaseous fuels, raw materials for the chemical industry |
| Gasoline | 40-200 | Hydrocarbons C 5 – C 9 | Aviation and automobile fuel, solvent |
| Naphtha | 150-250 | Hydrocarbons C 9 – C 12 | Diesel fuel, solvent |
| Kerosene | 180-300 | Hydrocarbons C 9 -C 16 | Fuel for diesel engines, household fuel, lighting fuel |
| Gas oil | 250-360 | Hydrocarbons C 12 -C 35 | Diesel fuel, feedstock for catalytic cracking |
| Fuel oil | > 360 | Higher hydrocarbons, O-, N-, S-, Me-containing substances | Fuel for boiler plants and industrial furnaces, raw materials for further distillation |
Fuel oil accounts for about half the mass of oil. Therefore, it is also subjected to thermal processing. To prevent decomposition, fuel oil is distilled under reduced pressure. In this case, several fractions are obtained: liquid hydrocarbons, which are used as lubricating oils ; mixture of liquid and solid hydrocarbons – petrolatum , used in the preparation of ointments; mixture of solid hydrocarbons – paraffin , used for the production of shoe polish, candles, matches and pencils, as well as for impregnating wood; non-volatile residue - tar , used to produce road, construction and roofing bitumen.
Oil recycling includes chemical reactions, changing the composition and chemical structure of hydrocarbons. Its variety is
ty – thermal cracking, catalytic cracking, catalytic reforming.
Thermal cracking usually subject to fuel oil and other heavy fractions of oil. At a temperature of 450-550°C and a pressure of 2–7 MPa, hydrocarbon molecules are split by the free radical mechanism into fragments with a smaller number of carbon atoms, and saturated and unsaturated compounds are formed:
S 16 H 34 ¾® S 8 H 18 + S 8 H 16
C 8 H 18 ¾®C 4 H 10 +C 4 H 8
This method is used to obtain motor gasoline.
Catalytic cracking carried out in the presence of catalysts (usually aluminosilicates) at atmospheric pressure and temperature 550 - 600°C. At the same time, aviation gasoline is produced from kerosene and gas oil fractions of oil.
The breakdown of hydrocarbons in the presence of aluminosilicates occurs according to the ionic mechanism and is accompanied by isomerization, i.e. the formation of a mixture of saturated and unsaturated hydrocarbons with a branched carbon skeleton, for example:
CH 3 CH 3 CH 3 CH 3 CH 3
cat., t||
C 16 H 34 ¾¾® CH 3 -C -C-CH 3 + CH 3 -C = C - CH-CH 3
Catalytic reforming carried out at a temperature of 470-540°C and a pressure of 1–5 MPa using platinum or platinum-rhenium catalysts deposited on an Al 2 O 3 base. Under these conditions, the transformation of paraffins and
cycloparaffins petroleum into aromatic hydrocarbons
cat., t, p
¾¾¾¾® + 3Н 2
cat., t, p
C 6 H 14 ¾¾¾¾® + 4H 2
Catalytic processes make it possible to obtain gasoline of improved quality due to its high content of branched and aromatic hydrocarbons. The quality of gasoline is characterized by its octane number. The more the mixture of fuel and air is compressed by the pistons, the greater the engine power. However, compression can only be carried out to a certain limit, above which detonation (explosion) occurs.
gas mixture, causing overheating and premature engine wear. Normal paraffins have the lowest resistance to detonation. With a decrease in chain length, an increase in its branching and the number of double
It increases in the number of connections; it is especially high in aromatic hydrocarbons
before giving birth. To assess the resistance to detonation of various types of gasoline, they are compared with similar indicators for the mixture isooctane And n-hep-tana with different ratios of components; The octane number is equal to the percentage of isooctane in this mixture. The higher it is, the higher the quality of gasoline. The octane number can also be increased by adding special anti-knock agents, for example, tetraethyl lead Pb(C 2 H 5) 4, however, such gasoline and its combustion products are toxic.
In addition to liquid fuel, catalytic processes produce lower gaseous hydrocarbons, which are then used as raw materials for organic synthesis.
Another important natural source of hydrocarbons, the importance of which is constantly increasing, is natural gas. It contains up to 98% vol. methane, 2–3% vol. its closest homologues, as well as impurities of hydrogen sulfide, nitrogen, carbon dioxide, noble gases and water. Gases released during oil production ( passing ), contain less methane, but more of its homologues.
Natural gas is used as fuel. In addition, individual saturated hydrocarbons are isolated from it by distillation, as well as synthesis gas , consisting mainly of CO and hydrogen; they are used as raw materials for various organic syntheses.
Mined in large quantities coal – heterogeneous solid material of black or gray-black color. It is a complex mixture of various high molecular weight compounds.
Coal is used as a solid fuel and is also subjected to coking – dry distillation without air access at 1000-1200°C. As a result of this process, the following are formed: coke , which is finely ground graphite and is used in metallurgy as a reducing agent; coal tar , which is distilled to produce aromatic hydrocarbons (benzene, toluene, xylene, phenol, etc.) and pitch used for the preparation of roofing felt; ammonia water And coke oven gas , containing about 60% hydrogen and 25% methane.
Thus, natural sources of hydrocarbons provide
the chemical industry with a variety of and relatively cheap raw materials for carrying out organic syntheses, which make it possible to obtain numerous organic compounds that are not found in nature, but are necessary for humans.
General scheme The use of natural raw materials for basic organic and petrochemical synthesis can be presented as follows.
Arenas Synthesis gas Acetylene AlkenesAlkanes
Basic organic and petrochemical synthesis
Test tasks.
1222. What is the difference between primary oil refining and recycling?
1223. What compounds determine high quality gasoline?
1224. Suggest a method that makes it possible to obtain ethyl alcohol from oil.
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 have accumulated solar heat and energy that 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
Hard coal is a complex mixture of high-molecular compounds, which include the following elements: C, H, N, O, S. Hard 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 allow the use of low-quality brown and hard coals at thermal power plants without polluting environment 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 found under the layer permafrost and at great depths of 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 leaves no 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, Volga-Ural basin, in the North Caucasus (Stavropol), in the Komi Republic, Astrakhan region, Barents Sea.
Chapter 1. GEOCHEMISTRY OF OIL AND FOSSIL EXPLORATION.. 3
§ 1. Origin of fossil fuels. 3
§ 2. Gas and oil rocks. 4
Chapter 2. NATURAL SOURCES... 5
Chapter 3. INDUSTRIAL PRODUCTION OF HYDROCARBONS... 8
Chapter 4. OIL PROCESSING... 9
§ 1. Fractional distillation.. 9
§ 2. Cracking. 12
§ 3. Reforming. 13
§ 4. Sulfur removal.. 14
Chapter 5. APPLICATIONS OF HYDROCARBONS... 14
§ 1. Alkanes.. 15
§ 2. Alkenes.. 16
§ 3. Alkynes.. 18
§ 4. Arenas.. 19
Chapter 6. State Analysis oil industry. 20
Chapter 7. Features and main trends in the oil industry. 27
List of used literature... 33
The first theories that considered the principles determining the occurrence of oil deposits were usually limited mainly to the question of where it accumulated. However, over the past 20 years it has become clear that to answer this question it is necessary to understand why, when and in what quantities oil was formed in a particular basin, as well as to understand and establish as a result of what processes it originated, migrated and accumulated. This information is absolutely necessary to improve the efficiency of oil exploration.
The formation of hydrocarbon fossils, according to modern views, occurred as a result of a complex sequence of geochemical processes (see Fig. 1) inside the original gas and oil rocks. In these processes, the components of various biological systems (substances of natural origin) were converted into hydrocarbons and, to a lesser extent, into polar compounds with different thermodynamic stability - as a result of the precipitation of substances of natural origin and their subsequent covering with sedimentary rocks, under the influence of elevated temperature and elevated pressure in the surface layers of the earth's crust. The primary migration of liquid and gaseous products from the initial gas-oil layer and their subsequent secondary migration (through bearing horizons, shifts, etc.) into porous oil-saturated rocks leads to the formation of deposits of hydrocarbon materials, the further migration of which is prevented by locking the deposits between non-porous layers of rocks .
In extracts of organic matter from sedimentary rocks of biogenic origin, compounds with the same chemical structure as those found in petroleum are found. Some of these compounds, which are considered “biological markers” (“chemical fossils”), are of particular importance for geochemistry. Such hydrocarbons have much in common with compounds found in biological systems (for example, lipids, pigments and metabolites) from which oil was formed. These compounds not only demonstrate the biogenic origin of natural hydrocarbons, but also make it possible to obtain very important information about gas and oil-bearing rocks, as well as about the nature of maturation and origin, migration and biodegradation that led to the formation of specific gas and oil deposits.
Figure 1 Geochemical processes leading to the formation of fossil hydrocarbons.
A gas-oil rock is considered to be a finely dispersed sedimentary rock that, when naturally deposited, has led or could lead to the formation and release of significant quantities of oil and (or) gas. The classification of such rocks is based on the content and type of organic matter, the state of its metamorphic evolution (chemical transformations occurring at temperatures of approximately 50-180 ° C), and the nature and quantity of hydrocarbons that can be obtained from it. Organic matter kerogen in sedimentary rocks of biogenic origin can be found in the most various forms, but it can be divided into four main types.
1) Liptinites– have a very high hydrogen content but low oxygen content; their composition is determined by the presence of aliphatic carbon chains. It is assumed that liptinites formed mainly from algae (usually subjected to bacterial decomposition). They have a high ability to convert into oil.
2) exits– have a high hydrogen content (however lower than that of liptinites), rich in aliphatic chains and saturated naphthenes (alicyclic hydrocarbons), as well as aromatic rings and oxygen-containing functional groups. This organic matter is formed from plant materials such as spores, pollen, cuticles and other structural parts of plants. Exinites have a good ability to transform into oil and gas condensate, and at higher stages of metamorphic evolution into gas.
3) Vitrshita– have a low hydrogen content, high oxygen content and consist primarily of aromatic structures with short aliphatic chains linked by oxygen-containing functional groups. They are formed from structured woody (lignocellulosic) materials and have limited ability to convert to oil, but good ability to convert to gas.
4) Inertinites are black, opaque clastic rocks (high carbon and low hydrogen) that were formed from highly modified woody precursors. They do not have the ability to turn into oil and gas.
The main factors by which a gas-oil rock is recognized are its kerogen content, the type of organic matter in the kerogen, and the stage of metamorphic evolution of this organic matter. Good gas-oil rocks are those that contain 2-4% organic matter of the type from which the corresponding hydrocarbons can be formed and released. Under favorable geochemical conditions, oil formation can occur from sedimentary rocks containing organic matter such as liptinite and exinite. The formation of gas deposits usually occurs in rocks rich in vitrinite or as a result of thermal cracking of the originally formed oil.
As a result of the subsequent burial of sediments of organic matter under top layers sedimentary rocks, this substance is exposed to increasingly high temperatures, which leads to the thermal decomposition of kerogen and the formation of oil and gas. The formation of oil in quantities of interest for the industrial development of the field occurs under certain conditions in time and temperature (depth of occurrence), and the formation time is longer, the lower the temperature (this is not difficult to understand if we assume that the reaction proceeds according to the first order equation and has an Arrhenius dependence on temperature). For example, the same amount of oil that was formed at a temperature of 100°C in approximately 20 million years should be formed at a temperature of 90°C in 40 million years, and at a temperature of 80°C in 80 million years. The rate of formation of hydrocarbons from kerogen approximately doubles for every 10°C increase in temperature. However chemical composition kerogen. can be extremely varied, and therefore the indicated relationship between the time of oil maturation and the temperature of this process can only be considered as a basis for approximate estimates.
Modern geochemical studies show that in continental shelf North Sea Every 100 m increase in depth is accompanied by an increase in temperature of approximately 3°C, meaning that the organic-rich sedimentary rocks formed liquid hydrocarbons at depths of 2500-4000 m over a period of 50-80 million years. Light oils and condensates apparently formed at a depth of 4000-5000 m, and methane (dry gas) at a depth of more than 5000 m.
Natural sources of hydrocarbons are fossil fuels - oil and gas, coal and peat. Crude oil and gas deposits arose 100-200 million years ago from microscopic marine plants and animals that became embedded in sediments formed on the seabed. In contrast, coal and peat began to form 340 million years ago from plants that grew on land.
Natural gas and crude oil are typically found along with water in oil-bearing strata located between layers of rock (Figure 2). The term "natural gas" also applies to gases that are formed in natural conditions as a result of coal decomposition. Natural gas and crude oil are developed on every continent except Antarctica. The world's largest producers of natural gas are Russia, Algeria, Iran and the 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 that can vary in color 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 the number of carbon atoms from five to 40. The industrial name of these cycloalkanes is nachtany. Crude oil also contains approximately 10% aromatic hydrocarbons, as well as small amounts of other compounds containing sulfur, oxygen and nitrogen.
Natural springs hydrocarbons Full name Starchevaya Arina Group B-105 2013
Natural sources Natural sources of hydrocarbons are fossil fuels - oil and gas, coal and peat. Crude oil and gas deposits arose 100-200 million years ago from microscopic marine plants and animals that became embedded in sedimentary rocks formed on the sea floor. In contrast, coal and peat began to form 340 million years ago from plants growing on land. .
Natural gas and crude oil are typically found along with water in oil-bearing strata located between layers of rock (Figure 2). The term “natural gas” also applies to gases that are formed in natural conditions as a result of the decomposition of coal. Natural gas and crude oil are developed on every continent except Antarctica. The world's largest producers of natural gas are Russia, Algeria, Iran and the United States. The largest producers of crude oil are Venezuela, Saudi Arabia, Kuwait and Iran. Natural gas consists mainly of methane. Crude oil is an oily liquid that can vary in color 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 the number of carbon atoms from five to 50. The industrial name of these cycloalkanes is nachtany. Crude oil also contains approximately 10% aromatic hydrocarbons, as well as small amounts of other compounds containing sulfur, oxygen and nitrogen.
Natural gas is used both as a fuel and as a raw material for the production of a variety of organic and inorganic substances. You already know that hydrogen, acetylene and methyl alcohol, formaldehyde and formic acid, and many other organic substances are obtained from methane, the main component of natural gas. Natural gas is used as fuel in power plants, in boiler systems for water heating of residential and industrial buildings, in blast furnace and open-hearth industries. By striking a match and lighting the gas in the kitchen gas stove of a city house, you “trigger” a chain reaction of oxidation of alkanes that make up natural gas. In addition to oil, natural and associated petroleum gases, coal is a natural source of hydrocarbons. 0n forms thick layers in the bowels of the earth, its proven reserves significantly exceed oil reserves. Like oil, coal contains a large amount of various organic substances. In addition to organic substances, it also contains inorganic substances, such as water, ammonia, hydrogen sulfide and, of course, carbon itself - coal. One of the main methods of processing coal is coking - calcination without air access. As a result of coking, which is carried out at a temperature of about 1000 ° C, the following are formed: coke oven gas, which includes hydrogen, methane, carbon dioxide and carbon dioxide, impurities of ammonia, nitrogen and other gases; coal tar containing several hundred times-personal organic substances, including benzene and its homologues, phenol and aromatic alcohols, naphthalene and various heterocyclic compounds; tar, or ammonia water, containing, as the name implies, dissolved ammonia, as well as phenol, hydrogen sulfide and other substances; coke is a solid residue from coking, almost pure carbon. Coke is used in the production of iron and steel, ammonia is used in the production of nitrogen and combined fertilizers, and the importance of organic coking products can hardly be overestimated. Thus, associated petroleum and natural gases, coal are not only the most valuable sources of hydrocarbons, but also part of a unique storehouse of irreplaceable natural resources, the careful and reasonable use of which is a necessary condition for the progressive development of human society.
Crude oil is a complex mixture of hydrocarbons and other compounds. In this form it is rarely used. It is first processed into other products that have practical applications. Therefore, crude oil is transported by tankers or pipelines to refineries. Petroleum refining involves a number of physical and chemical processes: fractional distillation, cracking, reforming and desulfurization.
Crude oil is divided into many components, subjecting it to simple, fractional and vacuum distillation. The nature of these processes, as well as the number and composition of the resulting oil fractions, depend on the composition of the crude oil and on the requirements for its various fractions. First of all, gas impurities dissolved in it are removed from crude oil by subjecting it to simple distillation. The oil is then subjected to primary distillation, as a result of which it is separated into gas, light and medium fractions and fuel oil. Further fractional distillation of light and medium fractions, as well as vacuum distillation of fuel oil leads to the formation large number factions. In table 4 shows the boiling point ranges and composition of various oil fractions, and Fig. Figure 5 shows a diagram of the design of a primary distillation (distillation) column for oil distillation. Let us now move on to a description of the properties of individual oil fractions.
Oil fields contain, as a rule, large accumulations of so-called associated petroleum gas, which collects above the oil in earth's crust and partially dissolves in it under the pressure of overlying rocks. Like oil, associated petroleum gas is a valuable natural source of hydrocarbons. It contains mainly alkanes, whose molecules contain from 1 to 6 carbon atoms. It is obvious that the composition of associated petroleum gas is much poorer than oil. However, despite this, it is also widely used both as a fuel and as a raw material for the chemical industry. Just a few decades ago, in most oil fields, associated petroleum gas was burned as a useless supplement to oil. Currently, for example, in Surgut, the richest oil reserve in Russia, the cheapest electricity in the world is generated using associated petroleum gas as fuel.
Thank you for your attention.
– 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
