Ammonia production in industry. Getting ammonia in the lab
A number of factors influence the process of producing the optimal amount of a chemical, as well as achieving its maximum quality. The production of ammonia depends on the pressure, temperature, the presence of a catalyst, the substances used and the method of extraction of the material obtained. These parameters must be properly balanced to achieve the greatest profit from the production process.
At room temperature and normal air humidity, ammonia is in a gaseous state and has a very repulsive odor. It is endowed with poisonous and irritating mucous membranes effects on the body. The production and properties of ammonia depend on the participation of water in the process, since this substance is very soluble in the normal characteristics of the environment.
Ammonia is a compound of hydrogen and nitrogen. Its chemical formula is NH3.
This chemical substance acts as an active reducing agent, as a result of which free nitrogen is released. Ammonia exhibits characteristics of bases and alkalis.
Reaction of a substance with water
When NH is dissolved3ammonia water is produced in water. Maximum at normal temperature can be dissolved in 1 volume of water element 700 volumes of ammonia. This substance is known as ammonia and is widely used in the fertilizer industry, in process plants.
Obtained by dissolving in water NH3by its qualities partially ionized.
Ammonia is used in one of the methods of laboratory receipt of this element.
Receipt of substances in the laboratory
The first method of producing ammonia is to bring ammonia to a boil, after which the resulting steam is dried and the desired chemical compound is collected. The production of ammonia in the laboratory is also possible by heating slaked lime and solid ammonium chloride.
The reaction of obtaining ammonia has the following form:
2NH4Cl + Ca (OH)2→ CaCl2+ 2NH3+ 2H2O
In the course of this reaction a white precipitate appears. This is salt CaCl2, and still formed water and the desired ammonia.To drain the desired substance it is passed through a mixture of lime in combination with sodium.
Getting ammonia in the laboratory does not provide the most optimal technology of its production in the required quantities. For many years people have been looking for ways to extract matter on an industrial scale.
The origins of the establishment of production technologies
During 1775-1780, experiments on the binding of free nitrogen molecules from the atmosphere were carried out. Swedish chemist K. Schelet found a reaction that looked like
Na2CO3+ 4C + N2= 2NaCN + 3CO
On this basis, in 1895, N. Caro and A. Frank developed a method for binding free nitrogen molecules:
Cac2+ N2= CaCN2+ C
This option required a lot of energy and was economically unprofitable, so over time it was abandoned.
Another rather expensive method was the process of interaction of nitrogen and oxygen molecules discovered by the British chemists D. Priestley and G. Cavendish:
N2+ O2= 2NO
Ammonia demand growth
In 1870, this chemical was considered an undesirable product of the gas industry and was practically useless. However, 30 years later it became very popular in the coke industry.
At first, the increased need for ammonia was replenished by isolating it from coal.But with an increase in the consumption of a substance 10 times, practical work was carried out to find ways to extract it. Ammonia production began to be introduced using atmospheric nitrogen reserves.
The need for nitrogen-based substances was observed in almost all known sectors of the economy.
Finding ways to meet industrial demand
A long way passed humanity to the implementation of the equation of production of substances:
N2+ 3H2= 2NH3
The production of ammonia in industry was first realized in 1913 by catalytic synthesis from hydrogen and nitrogen. The method was discovered by F. Haber in 1908.
Open technology has solved the long-standing problem of many scientists from different countries. Up to this point, it was not possible to bind nitrogen in the form of NH3. This chemical process is called cyanamide reaction. With an increase in the temperature of lime and carbon, the substance CaC was obtained.2(calcium carbide). By heating the nitrogen and achieving calcium cyanamide CaCN2, from which the release of ammonia took place by hydrolysis.
Introduction of ammonia technology
Getting NH3globally, industrial consumption began with the purchase of a patent for technology F.Haber representative of the Baden soda plant A. Mittash. In early 1911, ammonia synthesis on a small plant became regular. K. Bosch created a large contact apparatus, based on the developments of F. Haber. It was the original equipment that provided the ammonia extraction process through synthesis on an industrial scale. K. Bosch took over the entire manual on this issue.
Saving energy costs involved participation in the synthesis of certain catalysts.
A group of scientists working on finding the right ingredients suggested the following: an iron catalyst in which potassium and aluminum oxides were added and which is still considered one of the best for producing ammonia in industry.
09/09/1913 the first plant in the world using catalytic synthesis technology began its work. Production capacities were gradually increased, and by the end of 1917 7 thousand tons of ammonia were produced per month. In the first year of operation of the plant, this figure was only 300 tons per month.
Subsequently, in all other countries, they also began to apply the technology of synthesis using catalysts, which in essence was not very different from the Haber-Bosch technique.The use of high pressure and circulation processes occurred in any process.
The introduction of synthesis in Russia
Synthesis with the use of catalysts providing ammonia was also used in Russia. The reaction has the following form:
N2+ 3H2↔ 2 NH3↑ + 45.9 kJ
In Russia, the very first ammonia synthesis plant began its work in 1928 in Chernorechensk, and then production was built in many other cities.
Practical work on getting ammonia is constantly gaining momentum. In the period from 1960 to 1970, the synthesis increased almost 7 times.
In the country, mixed catalytic substances are used to successfully obtain, collect and recognize ammonia. The study of their composition is carried out by a group of scientists led by S. S. Lachinov. This group has found the most effective materials for the technology of the synthesis.
Also, studies of the kinetics of the process are constantly conducted. MI Temkin and his collaborators conducted scientific research in this area. In 1938, this scientist, together with his colleague V. M. Pyzhev, made an important discovery, perfecting the production of ammonia. The synthesis kinetics equation compiled by these chemists is now applied throughout the world.
Modern synthesis process
The process of producing ammonia using a catalyst used in today's production is reversible. Therefore, the issue of the optimal level of the impact of indicators on the achievement of maximum output is very topical.
The process takes place at a high temperature: 400-500 ˚С. A catalyst is used to provide the required rate of reaction. Modern getting NH3involves the use of high pressure - about 100-300 atm.
Together with the use of the circulation system, a sufficiently large mass of the original materials converted into ammonia can be obtained.
The system of operation of any ammonia plant is quite complex and contains several stages. The technology of obtaining the desired substance is carried out in 6 stages. In the course of the synthesis, ammonia is obtained, collected and recognized.
The initial stage is to extract sulfur from natural gas using a desulfurizer. This manipulation is required due to the fact that sulfur is a catalytic poison and kills the nickel catalyst even at the stage of hydrogen extraction.
At the second stage, methane conversion takes place, which proceeds with the use of high temperature and pressure using a nickel catalyst.
At the third stage, a partial burnout of hydrogen in the oxygen of the air occurs. The result is a mixture of water vapor, carbon monoxide, and nitrogen.
At the fourth stage, a shear reaction occurs, which takes place under different catalysts and two different temperature conditions. Originally applied Fe3O4, and the process proceeds at a temperature of 400 ˚C. In the second stage, a more efficient copper catalyst is involved, which allows production at low temperatures.
The next fifth stage involves the elimination of unnecessary carbon monoxide (VI) from the gas mixture by applying the technology of absorption with an alkali solution.
At the final stage, carbon monoxide (II) is removed by using the reaction of conversion of hydrogen to methane through a nickel catalyst and a higher temperature.
The gas mixture obtained as a result of all manipulations contains 75% hydrogen and 25% nitrogen. It is compressed under great pressure, and then cooled.
It is these manipulations that the ammonia release formula describes:
N2+ 3H2↔ 2 NH3↑ + 45.9 kJ
Although this process does not look very difficult, however, all the above actions for its implementation indicate the difficulty of obtaining ammonia on an industrial scale.
The quality of the final product is influenced by the absence of impurities in the raw material.
Having gone a long way from a small laboratory experience to large-scale production, ammonia production today is a popular and indispensable branch of the chemical industry. This process is constantly being improved, ensuring the quality, efficiency and the necessary amount of product for each cell of the national economy.