Three sources of raw materials are important for industry: oil, gas and coal.
Oil.
Oil is a dark, oily liquid, insoluble in water, which contains branched and unbranched alkanes, cycloalkanes. The composition depends on the deposit.
Oil is the main material for obtaining organic compounds by dry distillation (pyrolysis, carbonization). The main products are aromatic hydrocarbons and their derivatives. They receive mainly dyes, synthetic fats and oils.
With the growing importance of oil, the methods of chemical processing improved. Currently, about 90% of synthetic organic compounds are derived from petroleum and its derivatives.
Laboratory and industrial methods for obtaining oil.
There are a number of significant differences between laboratory and industrial methods of obtaining oil, namely:
- price (in the laboratory, small quantities of reagents are used, while in the industry large volumes are needed. Therefore, expensive and rare compounds can be used in the laboratory, and in industry it is necessary to bypass least cost. Or the use of harmful toxic substances in the laboratory is quite acceptable due to the presence fume hoods, then on an industrial scale it is extremely dangerous.);
- warmly. In industry, the supply of heat is very expensive for reactions carried out at moderately elevated and normal temperatures, when, as for the laboratory, such syntheses are easily feasible;
- the purity of the mixture. In the laboratory, they usually work with pure substances, while in industry, mainly with mixtures;
- circulation of matter. If in industry it is possible to separate mixtures by various chemical processes (distillation, filtration, continuous processes), then this is unprofitable for the laboratory. In industry, there is a cyclical process, when an unreacted substance can be re-introduced into the cycle of the processing process, and in the laboratory this is done with great difficulty.
Oil refining.
In industry, fractional distillation of "crude oil" is used, as a result of which the latter is divided into several fractions that have different boiling points:
Gasoline fraction consists of petroleum ether and extraction gasoline. The composition of the fraction varies from From 6 - From 9. The entire fraction is a significant oil product, because serves as fuel for internal combustion engines.
Kerosene (С 9 -С 16) used in heating appliances, and is also a fuel for aircraft and turbine engines.
Gas oil (diesel fuel) serves as fuel for diesel engines.
Lubricating oils (C 20 - C 50) used as lubricants.
Fuel oil (residue)- used as a fuel, it is distilled as a result of which a high-boiling hydrocarbon fraction is obtained.
Chemical transformations of hydrocarbons contained in oil.
Importance of fuel in modern world increases significantly. It is for this reason that they found the most best way obtaining gasoline from high-boiling fractions - cracking - heating of higher alkanes without air access, as a result of which decomposition into lower and higher hydrocarbons occurs:
If cracking proceeds without the use of a catalyst, then it is called thermal. If the catalyst is used SiO 2 or Al 2 O 3 , then this is catalytic cracking. The product of such processes is ethane and propene, which have become important raw materials for industry.
To improve the quality of gasoline, reforming and alkylation are carried out.
Reforming(isomerization) - a process in which unbranched alkanes, when heated with a catalyst, are converted into more branched ones with a higher octane number. For example,
Alkylation- a process in which a mixture of alkanes and alkenes is converted into branched compounds with a high octane number, using an acid as a catalyst:
Natural gas.
Natural gas is a combination of gases, the composition of which depends on the field. Basically, it is a mixture of methane, ethane and propane, but small amounts of nitrogen, higher alkanes, carbon, helium (rarely) can also be found.
Natural gas is an industrial fuel, the most important compound is synthesis gas(mixture of carbon monoxide and hydrogen):
It can be obtained by exposure to hot coke with water vapor, the compound that is obtained in this process is called water gas:
It is from carbon monoxide and hydrogen that methanol is obtained:
The reaction proceeds under pressure in the presence of catalysts.
Coal.
Coal serves as a raw material for the production of aromatic hydrocarbons. Schematically, the process can be represented as follows:
Similarly, you can get toluene.
Dry distillation at high temperatures produces a mixture of solid, liquid and gaseous products.
gas phase product is an coke oven gas, the main components of which are hydrogen and methane.
liquid product represents tar from which is extracted a large number of phenol, cresol, naphthalene, thiophene, anthracene.
solid product is an coke.
Thoughts about what awaits us in the future have haunted scientists before. Today, everyone is talking about this topic: from government leaders to schoolchildren. Global warming, melting age-old ice, demographic problems, human cloning, modern and future means of communication and transportation, people's dependence on energy carriers ... Still, one of the most popular topics today is the issue of alternative fuel.
Fuel of the future - an alternative to natural resources
Natural fuels are currently our main source of energy. Hydrocarbons are burned to break molecular bonds and release their energy. High level consumption of fossil fuels leads to significant pollution natural environment when they are burned.
We live in the 21st century, this is the time of new technologies, and many scientists believe that the time has come to create an alternative fuel of the future that can replace traditional fuel and eliminate our dependence on it. Over the past 150 years, the use of hydrocarbons has increased the amount of carbon dioxide in the atmosphere by 25%. The burning of hydrocarbons also leads to other types of pollution, such as smog, acid rain and air pollution. This type of pollution not only harms environment, animal and human health, but also leads to wars, as fossil fuels are non-renewable resources and will eventually run out. On the this moment it is important to find new solutions and establish alternative fuel sources for the future.
While some scientists are solving the issue of increasing the oil recovery factor of productive formations, while others are looking for ways to obtain gaseous fuel from oil shale, others have come to the conclusion that the need for fuel can be met by the usual old-fashioned method. It's about about "solid oil products", natural fuel - firewood. The idea "as old as the world" was picked up by specialists from Stanford University in the USA, and scientists from the University of Georgia joined them. Of course, here we need special fast-growing varieties of trees such as alder or plane trees, which produce up to 40 tons of wood per 1 hectare per year.
Plane tree - Platanus - a mighty tree with a dense spreading crown and a thick trunk - the ancestor of an extensive family of plane trees. There are about 10 species in the plane tree genus. The height of the plane tree reaches 60m, and the circumference of the trunk - up to 18m! The trunk of a plane tree is of an even cylindrical shape, the bark is greenish - gray color, exfoliating. The leaves of the plane tree are palmately lobed, with elongated petioles.
After cutting down plane trees, foliage remains on the ground that can be used for natural fertilizer. Sycamore wood is crushed in crushers and fed into the furnace of power plants. A 125 km2 plane tree plantation area can provide energy to a city with a population of 80,000 people. In the cut areas, in 2-4 years, new plane trees suitable for fuel will grow from the shoots again. Scientists have calculated that if 3% of the territory of Russia and Ukraine is allocated for "energy plantations of plane trees" for growing natural fuel, then the countries could fully satisfy their fuel needs at the expense of firewood.
The main advantage of using "farmed fossil fuels", as opposed to "fossil fuels" (coal, natural gas and oil), is that during the growth process, the sycamore energy forest absorbs carbon dioxide, which is later released when it burns. This means that when plane trees are burned, the same amount of CO2 is released into the atmosphere, which was absorbed by the plane tree during its growth. When burning fossil fuels, we increase the CO2 content in the atmosphere, and this main reason global warming.
The new fuel holds promise as a valuable renewable energy source and will be more important in the future. Already today, for example, Europe's largest power plant on a plane tree is located in Simmering (Austria). Its capacity is 66 MW, with an annual consumption of 190 thousand tons of plane tree grown here within a radius of 100 km. And in Germany, the capacity of energy forests reaches 20 million cubic meters of wood per year.
New fuels
American supporters of the "woodenization" of domestic heating are echoed by their colleagues from Europe. In Belgium, for example, in 1988, the Saar newspaper published an article where it called firewood the natural fuel of the future, as an alternative to the use of petroleum products. For the same purposes, it is proposed to use waste paper. It's already on sale in stores. hand press for the manufacture of briquettes from waste paper, not inferior in their calorific value to brown coal.
You can also buy special economical stoves that work on the principle of a gas generator, the design of which prevents heat from escaping through chimney. Firewood and briquettes of waste paper burn in this furnace very slowly: a bundle - in 8 hours. At the same time, firewood burns completely, there is no release of ash and soot into the atmosphere. Heating the premises with such stoves is very profitable, because a kilogram of firewood with a comparable calorific value costs 10 times less than a liter of liquid fuel, for the storage of which special fuel containers are also required.
Fast-growing brown algae attracted the attention of another group of American scientists. Marine plantations are proposed to be processed into gaseous methane with the help of bacteria. It is also possible to obtain oil-like substances by heating. According to calculations, a natural farm in the ocean with an area of plantations of 40 thousand hectares will be able to supply energy to a city with a population of 50 thousand people in the future. Scientists from France suggest using unicellular algae as an alternative fuel. It turns out that these microscopic organisms release hydrocarbons in the course of their life. By growing algae in special containers and supplying them with carbon dioxide and mineral salts, it is possible to regularly “harvest hydrocarbons” and obtain natural fuel.
Natural "gas stations" found in the tropics South America, in the Philippines. Some types of vines and tropical trees contain natural fuel - "diesel oil", which does not even need to be distilled. Alternative fuel from vines burns perfectly in car engines, giving less toxic exhaust than gasoline. Suitable for the production of top-lives and Palm oil, from which it is relatively easy to obtain "solar oil".
But for now, it's all in the realm of science fiction. A more realistic project is to obtain synthetic fuel from charcoal. A fairly simple method was developed by US scientists. Coal is crushed, treated with a solvent, and hydrogen is added to the resulting mixture. From a ton of coal, almost 650 liters of synthetic fuel are obtained, from which synthetic gasoline can be produced.
US scientists are seriously engaged in underground gasification of coal seams. By pyrolysis, 40% methane gas, 45% coke and 3% liquid fuel are obtained from it. Specialists have developed a completely unexpected way to get the fuel of the future ... from garbage. Magnetic and non-magnetic metals are preliminarily extracted from human waste, which are then sent for remelting. New technology recycling of glass waste makes it possible to obtain glass from fragments that is cheaper and more High Quality than the original raw material. Waste residues are processed into coke, methane gas and liquid fuels. "Junk" oil products were tested at pilot plants - they burn beautifully. From a ton of garbage in this way they "extract" from 6 to 20 dollars. In 1976 - 1977 San Diego has opened a waste recycling plant.
However, they are successfully working on a similar problem in the UK. Here, a waste processing unit has been developed and is currently operating, in which, under the influence of high temperatures during the combustion of oxygen blown in, garbage (plastic packaging and bottles, food waste, scraps of newspapers, rags, etc.) is used to produce synthetic oil products and methane gas with hydrogen . Liquid synthetic fuels and gas are supposed to be stored in tanks and used partly to run a diesel engine, and partly to melt broken glass, from which building blocks can be obtained. In the future, it is planned to process waste in old blast furnaces. This will give high productivity, saving time and money for the construction of new waste incineration plants. As experiments have shown, the remaining slag will also go into action - it is suitable for replacing gravel when performing concrete work.
And here are two more ways to get synthetic gasoline. French engineer A. Roethlisberger obtained an alternative gasoline from dry corn stalks. The author argues that the new fuel of the future with an octane rating of 98 can be obtained from straw, sawdust, vegetable tops and other waste containing cellulose fibers. Under pressure from government agencies, the inventor classified the technology for the synthesis of new fuel, but it is known that the quality of new gasoline largely depends on complex stabilizing additives introduced into alcohols and isopropyl ethers obtained from cellulose. The new alternative fuel does not detonate, burns without smoke and odors. It can be mixed in any proportion with regular gasoline. At the same time, in the future, design changes in the engines are not required. France intends to eventually increase the production of new gasoline to 20 million tons per year.
Another inventor of artificial gasoline lives in Switzerland. starting material serves wood chips, corn husks, plastic bags. But the trouble is, the "gasoline of the future" smells like moonshine. The inventor has to pay 8% tax as for manufacturing alcoholic beverages. Nevertheless, 1 liter of artificial "gasoline of the future" costs 2 times cheaper than the real one, and the car works properly, like new.
The developments of the inventors are not limited to artificial gasoline, they are offered original methods production of hydrocarbon gas for domestic purposes. One of which was developed in Germany. as a new source alternative energy the future is a garbage dump in the suburban town of Schwerborn. When filling the landfill, a network of gas wells and pipelines was laid under it. It turns out that 1 kg of garbage gives up to 200 liters of gas, of which 100 liters is methane. So far, 40 m3 of gas is "extracted" from the landfill per hour.
New fuel heats industrial premises. It is planned to build a heating plant using alternative fuel to heat the village. According to calculations, the cost of obtaining alternative fuel will pay off in 3.5 years.
The second way is even more unexpected. The proposal was made by the authorities of the city of Ottapalam in the state of Kerala (India). The recipe for the new fuel is as follows: The well is filled with cow dung and hermetically sealed. The gas produced during fermentation is conveyed through connected pipes to the gas stoves in houses. Such a biogas plant fully satisfies the family's need for bioenergy for home use. Today, 53 models of biogas systems have been developed and applied in India. About 3.5 million families use them effectively. The country's government actively supports the spread of biogas plants. Already, this saves about 1.2 billion rupees a year.
Solar energy is the technology of the future
At the beginning of the article, we mentioned various new energy technologies. Photovoltaic systems (or solar panels) are another “future technology” that is already in use today.
Now many people use solar panels as a main or backup source of electricity for residential buildings and office buildings. If you have recently been at sea, you may have noticed that navigation buoys also use energy solar panels. They have long been “adopted” by the military: during Operation Desert Storm, field radios were equipped with lightweight ECD solar panels.
In the future, the use of solar panels will only grow. Recently, ECD, in collaboration with Texaco, proposed a technology to use solar energy to power oil production equipment in a 200-hectare oil field in Bakersfield, California. Previously, to extract three barrels of oil, one was burned in a steam generator. The use of solar energy will not only lead to a reduction in the consumption of irreplaceable resources, but will also reduce harmful emissions and noise.
Fossil fuels are oil, coal, oil shale, natural gas and its hydrates, peat and other combustible minerals and substances from the caustobiolith group, used mainly as fuel, mined underground or open way. Fossil fuels are formed from the fossilized remains of dead plants during decomposition under anaerobic conditions under the influence of heat and pressure in earth's crust over millions of years. Coal and peat are fuels that are formed as the remains of animals and plants accumulate and decompose. Fossil fuels are non-renewable natural resource, as accumulated over millions of years. According to the Energy Information Administration, in 2007 the primary sources of energy used were: oil - 36.0%, coal - 27.4%, natural gas - 23.0%, in total, the share of fossil fuels accounted for 86.4% of all sources (fossil and non-fossil) of consumed primary energy in the world. It should be noted that the composition of non-fossil energy sources includes: hydroelectric power plants - 6.3%, nuclear - 8.5%, and others (geothermal, solar, tidal, wind energy, wood and waste combustion) in the amount of 0.9%.
Oil (Greek ναφθα, or through Turkish neft, from Persian oil; goes back to Akkad. Napatum - flash, ignite) - natural oily flammable liquid, consisting of a complex mixture of hydrocarbons and some other organic compounds. The color of the oil is red-brown, sometimes almost black, although sometimes there is also a weakly colored yellow-green and even colorless oil; has a specific smell, common in sedimentary rocks of the Earth. Oil has been known to mankind since ancient times. However, today oil is one of the most important minerals for mankind.
Coal is a type of fossil fuel formed from parts of ancient plants underground without oxygen. The international name for carbon comes from lat. carbō ("coal"). Coal was the first fossil fuel used by man. He allowed to do industrial revolution, which, in turn, contributed to the development of the coal industry, providing it with more modern technology. Coal, like oil and gas, is organic matter that has been slowly decomposed by biological and geological processes. The basis of coal formation is plant residues. Depending on the degree of conversion and the specific amount of carbon in coal, four types of it are distinguished:
brown coals (lignites); coals; anthracites; graphites.
AT Western countries there is a slightly different classification - lignites, sub-bituminous coals, bituminous coals, anthracites and graphites, respectively.
Oil shale is a mineral from the group of solid caustobiolites, which, during dry distillation, gives a significant amount of resin (similar in composition to oil). Shales were mainly formed 450 million years ago at the bottom of the sea from plant and animal remains. Oil shale consists of predominant mineral (calcite, dolomite, hydromica, montmorillonite, kaolinite, feldspars, quartz, pyrite and others) and organic parts (kerogen), the latter is 10-30% of the mass of the rock and only in shales of the highest quality reaches 50-70%. The organic part is a bio- and geochemically transformed substance of the simplest algae, which retained its cellular structure (thallomoalginite) or lost it (colloalginite); in the form of an impurity in the organic part there are altered residues higher plants(vitrinitis, fusenite, lipoidinitis).
Natural gas is a mixture of gases formed in the bowels of the earth during the anaerobic decomposition of organic matter. Refers to minerals. Natural gas in reservoir conditions (conditions of occurrence in the earth's interior) is in a gaseous state - in the form of separate accumulations (gas deposits) or in the form of a gas cap of oil and gas fields, or in a dissolved state in oil or water. Under standard conditions (101.325 kPa and 20 °C), natural gas is only in the gaseous state. Also, natural gas can be in a crystalline state in the form of natural gas hydrates.
Gas hydrates (also natural gas hydrates or clathrates) are crystalline compounds formed under certain thermobaric conditions from water and gas. The name "clathrates" (from Latin clathratus - "to put in a cage") was given by Powell in 1948. Gas hydrates are non-stoichiometric compounds, that is, compounds of variable composition.
Shale natural gas (English shale gas) - natural gas extracted from oil shale and consisting mainly of methane.
Peat (German Torf) - a combustible mineral; formed by the accumulation of plant remains that have undergone incomplete decomposition in swamp conditions. Contains 50-60% carbon. Heat of combustion (maximum) - 24 MJ/kg. It is used in complex as fuel, fertilizer, thermal insulation material etc. The swamp is characterized by the deposition of incompletely decomposed organic matter on the soil surface, which later turns into peat. The layer of peat in swamps is at least 30 cm (if less, then these are wetlands).
Fossil fuels contain a high percentage of carbon and include fossil coal, oil and natural gas. In turn, oil, gas, and fossil coal were formed from the sediments of once living organisms under the influence of high temperature, pressure and anaerobic decomposition of dead organisms buried under a layer of sedimentary rocks. The age of organisms, depending on the type of fossil fuel, is usually millions of years, and sometimes exceeds 650 million years. More than 80% of the oil and gas currently in use was formed in strata that formed during the Mesozoic and Tertiary period between 180 and 30 million years ago from marine microorganisms that accumulated as sediment on the seafloor.
The main constituents of oil, as well as gas, formed at a time when organic residues were not yet completely oxidized, and carbon, hydrocarbons and similar components were present in small quantities. Sedimentary rocks covered the remains of these substances. The temperature and pressure increased, and the liquid hydrocarbon accumulated in the voids of the rocks.
Regarding the origin of oil and natural gas, there is an alternative hypothesis that attempts to explain the formation of some anomalous oil deposits.
Oil production - a sub-sector of the oil industry, a branch of the economy engaged in the extraction of a natural mineral - oil. Excavations on the banks of the Euphrates established the existence of an oil field for 6,000-4,000 years BC. It was used as a fuel, and oil bitumen - in the construction and road business. Oil was also known in ancient Egypt, where it was used to embalm the dead. Despite the fact that, starting from the 18th century, separate attempts were made to purify oil, nevertheless, until the second half of XIX century was used mainly in in kind. However, oil attracted close attention only after it was proved in Russia by the factory practice of the Dubinin brothers (since 1823), and in America by the chemist B. Silliman (1855), that kerosene, an illuminating oil similar to photogen, can be isolated from it. which was widely used at that time and was produced from certain types of coal and shale. This was facilitated by the developed in the middle of the XIX century new way oil production using boreholes instead of wells (mines). The first (exploratory) oil well was drilled in an industrial way on the Absheron Peninsula in 1847, the first production well was drilled on the river. Kudako in the Kuban in 1864. In the United States, the first well was drilled in 1859. When developing oil fields, fresh water(to maintain pressure in the reservoir), including mixed with associated petroleum gas (Water-gas impact) or various chemicals to increase oil recovery and combat water cut in production wells. Due to the fact that oil reserves on land are depleted, further improvement in the technology of the extractive sub-sector of the oil industry has made it possible to start developing oil fields on the continental shelf using oil platforms.
To extract coal from great depths mines have been used by mankind for a long time. The deepest mines in the territory Russian Federation coal is mined from a depth of just over 1,200 meters. Along with coal, coal-bearing deposits contain many types of georesources that have consumer significance. These include host rocks as raw materials for the construction industry, groundwater, coal-bed methane, rare and trace elements, including precious metals and their connections. The use of jets as a destruction tool in the executive bodies of shearers and roadheaders is of particular interest. At the same time, there is a constant growth in the development of equipment and technology for the destruction of coal, rocks high-speed jets of continuous, pulsating and pulsed action.
Coal gasification - modern gas generators have a capacity for the transformation of solid fuels from 60,000 m³/h to 80,000 m³/h. Gasification technology is developing in the direction of increasing productivity (up to 200,000 m³ / h) and increasing efficiency (up to 90%) by increasing the temperature and pressure of this technological process(up to +2,000 °C and 10 MPa, respectively). Experiments were carried out on underground gasification of coal, the extraction of which, for various reasons, is economically unprofitable.
- 165.93 Kbnatural springs hydrocarbons
Oil, gas and coal
11.11.2011
MOU PSSH No. 1
Otinova Valentina Andreevna 10(4) class
1. Oil
a) Physical properties:
fractional distillation
b) Chemical properties:
cracking, thermal, catalytic cracking
c) Getting
d) Application
2. Gas
a) Receipt
b) Application
3. Coal
a) Hard coal, coking
b) Application
Conclusion
Oil
Physical properties
Oil is an oily flammable liquid with a specific
smell, usually brown with a greenish or other tinge,
sometimes almost black, very rarely colorless.
The main property of oil, which brought them world fame as exceptional
energy carriers is their ability to release significant
quantity of heat. Oil and its derivatives have the highest
types of fuel calorific value. The heat of combustion of oil - 41 MJ / kg, gasoline
– 42 MJ/kg. An important indicator for oil is the boiling point,
which depends on the structure of the hydrocarbons that make up the oil and
ranges from 50 to 550°C.
Oil, like any liquid, boils at a certain temperature and
goes into the gaseous state. The various components of the oil are converted into
gaseous state at different temperature. So the boiling point
methane -161.5°С, ethane -88°С, butane 0.5°С, pentane 36.1°С. Light oil
they boil at 50–100°C, heavy ones at temperatures above 100°C.
Oil can be divided into its components, for this it is purified from mechanical impurities or subjected to the so-called fractional distillation.
Fractional distillation - a physical method for separating a mixture of components with different boiling points.
Distillation is carried out in special installations - distillation columns, in which the cycle of condensation and evaporation of liquid substances contained in oil is repeated.
Scheme of an industrial installation for continuous distillation of oil
The distillation column receives oil heated in a tubular furnace to a temperature of 320-350 °C. The distillation column has horizontal partitions with holes - the so-called plates, on which the oil fraction condenses.
In the process of rectification, oil is divided into the following fractions:
- Fractionation gases- a mixture of low molecular weight hydrocarbons (propane, butane)
- Gasoline fraction(gasoline) hydrocarbons from C 5 H 12 – C 11 H 24
- Naphtha fraction - hydrocarbons from C 8 H 18 – C 14 H 30
- Kerosene fraction– hydrocarbons from C 12 H 26 – C 18 H 38
- Diesel fuel– hydrocarbons from C 13 H 28 – C 19 H 36
Residue of oil distillation - fuel oil - contains hydrocarbons with a number of carbon atoms from 18 to 50. Distillation under reduced pressure from fuel oil produces solar oil (C 18 H 28 - C 25 H 52), lubricating oils (C 28 H 58 - C 38 H 78), petroleum jelly 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.
Chemical properties
Oils consist mainly of carbon - 79.5 - 87.5% and hydrogen -
11.0 - 14.5% by weight of oil. In addition to them, oils contain three more
elements are sulfur, oxygen and nitrogen. Their total number is usually 0.5
- eight %. In insignificant concentrations in oils there are elements:
vanadium, nickel, iron, aluminum, copper, magnesium, barium, strontium, manganese,
chromium, cobalt, molybdenum, boron, arsenic, potassium, etc. Their total content is not
exceeds 0.02 - 0.03% of the mass of oil. These elements form
organic and inorganic compounds that make up oil.
Oxygen and nitrogen are found in oils only in a bound state. Sulfur can
occur in the free state or be part of hydrogen sulfide.
As a result, the resulting oil rectification products are subjected to chemical processing, which includes a number of complex processes. One of them - cracking oil products.
Cracking - thermal decomposition of petroleum products, leading to the formation of hydrocarbons with a smaller number of carbon atoms in the molecule.
There are several types of cracking: thermal cracking, catalytic cracking, high pressure cracking, reduction cracking.
Thermal cracking
– splitting of hydrocarbon molecules with a long carbon chain into shorter ones under the influence of high temperature (470-550°C). Alkanes decompose due to the breaking of C–C bonds (stronger C–H bonds are retained at this temperature) and alkanes and alkenes with a smaller number of carbon atoms are formed.
For example:
C 6 H 14 C 2 H 6 + C 4 H 8
AT general view This process can be expressed as:
C n H 2n+2 C n-k H 2(n-k)+2 + C k H 2k
During conventional thermal cracking, many low molecular weight gaseous hydrocarbons are formed, which are used as raw materials for the production of alcohols, carboxylic acids, high molecular weight compounds (polyethylene).
catalytic cracking occurs in the presence of catalysts, which are used as natural aluminosilicates of the composition n Al 2 O 3 * m SiO 2 at 500°C. The implementation of cracking using catalysts leads to the formation of hydrocarbons having a branched or closed chain of carbon atoms in the molecule.
Cracking of petroleum products proceeds at high temperatures, so carbon deposits (soot) are often formed, polluting the surface of the catalyst, which sharply reduces its activity. Cleaning from carbon deposits - its regeneration - is the main condition for the practical implementation of catalytic cracking. Most easy way regeneration of the catalyst is its roasting, during which the carbon deposits are oxidized by atmospheric oxygen.
Catalytic cracking is a heterogeneous process involving solid (catalyst) and gaseous (hydrocarbon vapor) substances. Heterogeneous reactions (gas - solid) proceed faster with increasing surface area solid. Therefore, the catalyst is crushed, and its regeneration and cracking of hydrocarbons are carried out in a "fluidized bed", familiar to you from the production of sulfuric acid.
The cracking feedstock, such as gas oil, enters the reactor(scheme). The lower part of the reactor has a smaller diameter, so the feed vapor flow rate is very high. The gas moving at high speed captures the catalyst particles and carries them to the upper part of the reactor, where, due to the increase in its diameter, the flow rate decreases. Under the action of gravity, the catalyst particles fall into the lower, narrower part of the reactor, from where they are again carried upwards. Thus, each grain of the catalyst is in constant motion and is washed from all sides by a gaseous reagent.
Scheme of a catalytic cracking unit in a fluidized bed
Some catalyst grains enter the outer, wider part of the reactor and, encountering gas flow resistance, sink into lower part, where they are picked up by the gas flow and carried away to the regenerator. The use of cracking catalysts makes it possible to slightly increase the reaction rate, reduce its temperature, and improve the quality of cracked products.
The obtained hydrocarbons of the gasoline fraction mainly have a linear structure, which leads to a low knock resistance received gasoline.
Receipt
The oil field contains large accumulations of associated petroleum gas, which collects above the oil in the earth's crust and partially dissolves in it under the pressure of overlying rocks. Associated petroleum gas, like oil, is a valuable natural source of hydrocarbons. The composition of associated petroleum gas is much poorer than that of oil. Associated petroleum gas is richer in composition of various hydrocarbons than natural gas. Dividing them into fractions, they get:
- Gasoline(pentane and hexane);
- propane - butane mixture(propane and butane);
- dry gas(methane and ethane).
Application
Natural gasoline is used as a fuel for internal combustion engines and also as an additive to motor fuel to facilitate starting engines in winter conditions. Propane - butane mixture is used as household fuel and for filling lighters. Dry gas is widely used as a fuel. Petroleum gas is used as a raw material for chemical production. Hydrogen, acetylene, unsaturated and aromatic hydrocarbons and their derivatives are obtained from alkanes in the associated petroleum gas. Gaseous hydrocarbons can form independent accumulations - a natural gas deposit.
Natural gas
Natural gas - a mixture of gaseous saturated hydrocarbons with a small molecular weight. The main component of the gas is methane, the share of which, depending on the field, ranges from 75 to 99% by volume. Natural gas also includes ethane, propane, butane, isobutane, nitrogen and carbon dioxide.
Receipt
Natural gas deposits are found in porous rocks formed as a result of tectonic shifts. The layers covering these rocks do not allow gas to pass through. The composition of natural gas differs significantly from one field to another. Therefore, before use, natural gas must be treated to remove unwanted components such as sulphate, water, etc. Processing is usually carried out at the place of extraction. At the same time, the removal of sulfur compounds is particularly difficult, since when they are burned, toxic sulfur dioxide (SO 2) is released.
Application
Natural gas is used as a fuel and as a raw material for the production of a variety of organic and inorganic substances. Hydrogen, acetylene and methyl alcohol, formaldehyde and formic acid are obtained from methane. Natural gas is used as a fuel in power plants, in boiler systems for water heating of residential buildings and industrial buildings, in blast furnace and open-hearth production. The value of natural gas as a fuel also lies in the fact that it is an environmentally friendly mineral fuel. When it is burned, much less harmful substances are produced compared to other types of fuel. Therefore, natural gas is one of the main sources of energy in human activities.
In the chemical industry, natural gas is used as a raw material for the production of various organic substances, such as plastics, rubber, alcohol, and organic acids. It was the use of natural gas that helped synthesize many chemicals that do not exist in nature, such as polyethylene.
Coal
Coal - sedimentary rock, which is a product of deep decomposition of plant remains (tree ferns, horsetails and club mosses, as well as the first gymnosperms). Coal consists of organic and inorganic substances, such as water, ammonia, hydrogen sulfide and carbon - coal.
Coking - a method of processing coal, calcination without air access. At a temperature of about 1000 ° C, as a result of coking, the following are formed:
Short description
Oil is an oily flammable liquid with a specific
smell, usually brown with a greenish or other tinge,
sometimes almost black, very rarely colorless.
Natural and associated petroleum gases.
Natural gas is a mixture of gases, the main component of which is methane, the rest is ethane, propane, butane, and a small amount of impurities - nitrogen, carbon monoxide (IV), hydrogen sulfide and water vapor. 90% of it is used as fuel, the remaining 10% is used as a raw material for the chemical industry: the production of hydrogen, ethylene, acetylene, soot, various plastics, medicines, etc.
Associated petroleum gas is also natural gas, but it occurs together with oil - it is located above the oil or dissolved in it under pressure. Associated gas contains 30-50% methane, the rest is its homologues: ethane, propane, butane and other hydrocarbons. In addition, it contains the same impurities as in natural gas.
Three fractions of associated gas:
Gas gasoline; it is added to gasoline to improve engine starting;
Propane-butane mixture; used as household fuel;
dry gas; used to produce acylene, hydrogen, ethylene and other substances, from which, in turn, rubbers, plastics, alcohols, organic acids, etc. are produced.
Oil.
Oil is an oily liquid from yellow or light brown to black in color with a characteristic odor. It is lighter than water and practically insoluble in it. Oil is a mixture of about 150 hydrocarbons mixed with other substances, so it does not have a specific boiling point.
90% of the produced oil is used as raw material for production various kinds fuels and lubricants. At the same time, oil is a valuable raw material for the chemical industry.
Oil extracted from the bowels of the earth, I call crude. Crude oil is not used, it is processed. Crude oil is purified from gases, water and mechanical impurities, and then subjected to fractional distillation.
Distillation is the process of separating mixtures into individual components, or fractions, based on differences in their boiling points.
During the distillation of oil, several fractions of petroleum products are isolated:
The gas fraction (tboil = 40°C) contains normal and branched alkanes CH4 - C4H10;
Gasoline fraction (tboil = 40 - 200°C) contains hydrocarbons C 5 H 12 - C 11 H 24; during re-distillation, light oil products are released from the mixture, boiling in lower temperature ranges: petroleum ether, aviation and motor gasoline;
Naphtha fraction (heavy gasoline, boiling point = 150 - 250 ° C), contains hydrocarbons of the composition C 8 H 18 - C 14 H 30, used as fuel for tractors, diesel locomotives, trucks;
The kerosene fraction (tboil = 180 - 300°C) includes hydrocarbons of the composition C 12 H 26 - C 18 H 38; it is used as fuel for jet planes, rockets;
Gas oil (tboil = 270 - 350°C) is used as diesel fuel and is cracked on a large scale.
After distillation of the fractions, a dark viscous liquid remains - fuel oil. Solar oils, petroleum jelly, paraffin are isolated from fuel oil. The residue from the distillation of fuel oil is tar, it is used in the production of materials for road construction.
Oil recycling is based on chemical processes:
Cracking is the splitting of large hydrocarbon molecules into smaller ones. Distinguish between thermal and catalytic cracking, which is more common at present.
Reforming (aromatization) is the conversion of alkanes and cycloalkanes into aromatic compounds. This process is carried out by heating gasoline at high blood pressure in the presence of a catalyst. Reforming is used to obtain aromatic hydrocarbons from gasoline fractions.
Pyrolysis of petroleum products is carried out by heating petroleum products to a temperature of 650 - 800°C, the main reaction products are unsaturated gaseous and aromatic hydrocarbons.
Oil is a raw material for the production of not only fuel, but also many organic substances.
Coal.
Coal is also a source of energy and a valuable chemical raw material. The composition of coal is mainly organic matter, as well as water, minerals, which form ash when burned.
One of the types of processing of hard coal is coking - this is the process of heating coal to a temperature of 1000 ° C without air access. Coking of coal is carried out in coke ovens. Coke consists of almost pure carbon. It is used as a reducing agent in the blast-furnace production of pig iron at metallurgical plants.
Volatile substances during condensation coal tar (contains many different organic substances, most of which are aromatic), ammonia water (contains ammonia, ammonium salts) and coke oven gas (contains ammonia, benzene, hydrogen, methane, carbon monoxide (II), ethylene , nitrogen and other substances).