Ammonia synthesis process, ammonia synthesis process

Ammonia synthesis refers to the direct synthesis of ammonia from nitrogen and hydrogen under high temperature and high pressure and in the presence of catalysts. Synonyms: ammonia.

The English name of the molecular formula NH3 is synthetic ammonia. Except for a small amount of ammonia from coke oven gas, the vast majority of the world's ammonia is synthetic ammonia.

Synthetic ammonia is mainly used as fertilizer, refrigerant and chemical raw material.

Production method The main raw materials for the production of synthetic ammonia are natural gas, naphtha, heavy oil and coal (or coke).

Ammonia from natural gas. Natural gas is first desulfurized, then through secondary conversion, and then through carbon monoxide shift, carbon dioxide removal and other processes to obtain nitrogen-hydrogen mixture, which still contains carbon monoxide and carbon dioxide about volume), after methanation removal, pure gas with a molar ratio of hydrogen to nitrogen is 3, which is compressed by a compressor and enters the ammonia synthesis circuit to obtain product ammonia. The process of producing ammonia from naphtha is similar to this process.

Ammonia production from heavy oil. Heavy oil includes residue oil obtained from various deep processing, and synthetic ammonia raw gas can be prepared by partial oxidation method, and the production process is simpler than that of natural gas vapor reforming, but an air separation device is required. The oxygen produced by the air separation unit is used for heavy oil and gasification, nitrogen is used as a raw material for ammonia synthesis, and liquid nitrogen is also used as a detergent for the removal of carbon monoxide, methane and argon.

Coal (coke) to ammonia. With the development of petrochemical industry and natural gas chemical industry, the method of producing ammonia from coal (coke) as raw material has been rarely used in the world.

Uses Ammonia is mainly used in the manufacture of nitrogen fertilizers and compound fertilizers, ammonia is used as industrial raw materials and ammoniad feed, and the amount is about 12% of the world's production. Nitric acid, various nitrogen-containing inorganic salts and organic intermediates, sulfonamides, polyurethanes, polyamide fibers and nitrile rubber all need to be directly used as raw materials. Liquid ammonia is often used as a refrigerant.

Storage and transportation Some of the ammonia in commercial ammonia is transported from the manufacturing plant to other places in liquid form. In addition, in order to ensure the balance between supply and demand between synthetic ammonia and ammonia processing plants in the manufacturing plant, and to prevent production shutdown due to short-term accidents, it is necessary to set up a liquid ammonia warehouse. According to the different capacity, there are three types of liquid ammonia storage: unfrozen, semi-frozen and fully frozen.

The transportation methods of liquid ammonia include sea transportation, barge transportation, pipeline transportation, tank truck transportation, and truck transportation.

Under the high pressure of 200MPa and the high temperature of 500 °C and the action of catalyst, N2+3H2====2NH3, after compression and condensation, the remaining material is sent back to the reactor for reaction

There are two main processes for the synthesis of ammonia.

1.Thermocatalytic ammonia synthesis.

Industrial ammonia synthesis is mainly controlled by the Haber-Bosch process. Ammonia is produced in a 3:1 ratio of hydrogen and nitrogen mixed in the presence of an iron-based catalyst in the temperature and pressure ranges of 723-873 K and 10-25 MPa, respectively.

The Haber-Bosch process has a conversion of about 15-25% to ammonia per run, and is ** by unreacted gases, resulting in a total conversion of 97%. The RU-based catalyst is the second generation catalyst, which can react at 300E450 and 4-15 MPa. Depending on the catalyst, the conditions are also different.

2.Electrochemical ammonia synthesis.

There are four categories based on the type of electrolyte used.

1) liquid electrolytes working at room temperature;

2) molten salt electrolytes operating at 573-773 K;

3) a composite electrolyte consisting of a solid electrolyte mixed with a low melting point salt operating at 573-973 K;

4) Solid electrolyte, operating from room temperature to a maximum of 1073 K.

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The first step is the preparation of the feed gas. To produce ammonia by synthetic method, it is first necessary to prepare feed gas containing hydrogen and nitrogen. It can be made by mixing hydrogen and nitrogen separately, or it can be produced at the same time.

The second step is the purification of the raw gas. The hydrogen and nitrogen raw gas produced contains impurities such as sulfur compounds, carbon monoxide, and carbon dioxide. These impurities can not only corrode equipment, but also poison ammonia synthesis catalysts.

Therefore, before the hydrogen and nitrogen raw gas is sent to the synthesis tower, it must be purified to remove various impurities and obtain a pure hydrogen and nitrogen mixture.

The third step is the compression of the feed gas and the synthesis of ammonia. The pure hydrogen-nitrogen mixture is compressed to high pressure and synthesized into ammonia at high temperatures and in the presence of a catalyst.

The raw materials for the production of synthetic ammonia are mainly coke, coal, natural gas, heavy oil, light oil and other fuels, as well as water vapor and air; The main process of producing synthetic ammonia is generally shown in the figure below.

Raw materials Preparation of raw gas Desulfurization Transformation of carbon monoxide Decarburization Removal of a small amount of carbon monoxide and carbon dioxide Synthesis of compressed ammonia Ammonia products.

The chemical equation for the reaction of industrial ammonia synthesis is: n +3h 2nh (catalyst, under high temperature and high pressure conditions).

The reaction process uses an iron catalyst (a catalyst mixed with iron as the main mixture), and the iron catalyst is most active at 500 °C, which is also the reason why the synthetic ammonia is selected at 500 °C.

Reaction characteristics of synthetic ammonia.

1) Reversible reaction;

2) The positive reaction is an exothermic reaction;

3) A positive reaction is a reaction in which the volume of a gas decreases.

The chemical equation for industrial ammonia synthesis: n (g) + 3h (g) = 2n h (g) (reversible reaction).

The vast majority of industrial ammonia production is produced by the synthesis of nitrogen and hydrogen under high pressure, high temperature and the presence of catalysts. Nitrogen is mainly found in air; Hydrogen is mainly used in syngas containing hydrogen and carbon monoxide (pure hydrogen is also used in the electrolysis of water).

The mixture of nitrogen and hydrogen is the raw gas for ammonia synthesis. The feed gas from the fuel chemical industry contains sulfur compounds and carbon oxides, which are toxic substances to the catalyst for ammonia synthesis and are purified before ammonia synthesis.

High temperature and high pressure. n (g) + 3h (g) = 2n h (g) (reversible reaction). rhθ=。

Ammonia industry.

N2 + 3H2 = high temperature, high pressure, catalyst = 2NH3 (reversible reaction) If you agree with my answer, please click the [Accept as satisfactory answer] button in time The mobile phone questioner can comment on [Satisfied] in the upper right corner of the client.

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N2 + 3H2 = High Temperature, High Pressure, Catalyst = 2NH3 (Reversible Reaction).

SCP-049 answers for you.

Ammonia synthesis is an important chemical that is widely used in the manufacture of fertilizers and other chemicals. This article will introduce the process flow diagram of ammonia synthesis and its process.

First of all, the production of synthetic ammonia requires the use of large amounts of natural gas and air. In this process, natural gas and air are mixed together and then changed through a series of oxygen and ant-stateization and reduction reactions. The purpose of these reactions is to combine nitrogen oxide with hydrogen to form ammonia and to expel some of the unreacted nitrogen from the system.

At this point, we have a gas containing a high concentration of ammonia.

Next, the gas must be dehydrated to remove the moisture from it. This can be done by passing the gas through one adsorbent. As the gas flows through the adsorbent, the moisture is absorbed by the material on it, allowing the moisture in the gas to be removed.

Finally, the gas used to synthesize ammonia needs to be compressed into a liquid, which can be done by a device called a throttle valve. The role of the throttle valve is to introduce the gas into a contractile and then pressurize it. The pressurized gas becomes a liquid that can be used in storage and transportation.

In conclusion, the process of ammonia synthesis involves many steps. However, it is only by understanding these steps that we can successfully manufacture high-quality fertilizers and other chemicals.

1) Feed gas preparation: First, raw materials such as coal and natural gas are made into crude feed gas containing hydrogen and nitrogen. For solid raw coal and coke, syngas is usually produced by gasification; Syngas can be obtained by non-catalytic partial oxidation of residual oil; For gaseous hydrocarbons and naphtha, syngas is produced by two-stage steam reforming method in industry.

2) Purification: Purify crude raw gas to remove impurities other than hydrogen and nitrogen, mainly including transformation process, desulfurization and decarburization process and gas refining process.

3) Finally, the pure hydrogen and nitrogen mixture is compressed to high pressure, and ammonia is synthesized under the action of a catalyst. Ammonia synthesis is the process of providing liquid ammonia products and is a core part of the entire ammonia production process. The ammonia synthesis reaction is carried out under the conditions of higher pressure and the presence of catalyst, because the ammonia content in the gas after the reaction is not high, and only 100 filial piety is generally returned, so the process of unreacted hydrogen and nitrogen circulation is adopted.

The chemical equation for industrial ammonia synthesis is the Haber-Bosch process: N2(G)+3H2(G) 2NH3(G).

In this equation, N2 represents nitrogen, H2 represents hydrogen, and NH3 represents ammonia. According to the equation, 1mol of nitrogen and 3mol of hydrogen react to produce 2mol of ammonia. This equation describes the synthesis reaction of nitrogen and hydrogen to produce ammonia.

The reaction is carried out at high temperatures (about 400-500°C) and high pressures (about 150-250 atmospheres) and usually requires the use of catalysts such as iron or iron-molybdenum to accelerate the reaction rate.

Industrial ammonia synthesis is an important chemical process used in the production of fertilizers and other chemicals. The discovery and application of this process has played an important role in solving the problem of nitrogen fertilizer in the agricultural field.

Conditions for industrial ammonia synthesis

1. Temperature: The industrial synthetic ammonia reaction needs to be carried out under high temperature conditions, usually between 400-500 °C. Higher temperatures can increase the reaction rate, but also increase energy consumption and the formation of reaction by-products.

2. Pressure: The reaction of industrial synthetic ammonia needs to be carried out under high pressure conditions, usually between 150-250 atmospheres. High pressure can increase the chance of nitrogen and hydrogen slag contact and promote the reaction.

3. Catalyst: The industrial ammonia synthesis reaction requires the use of catalysts to accelerate the reaction rate. Commonly used catalysts include iron (Fe) or iron-molybdenum (Fe-Mo) catalysts. These catalysts can reduce the activation energy of the reaction and increase the reactivity of nitrogen and hydrogen.

4. Gas ratio: The gas ratio of reactants is also an important condition affecting the reaction of industrial ammonia synthesis. In general, the molar ratio of the reactants is n2:h2=1:3.

5. Reactor design: In order to realize the industrial ammonia synthesis reaction under high temperature and high pressure conditions, it is necessary to design and use appropriate reactors. Common reactor designs include tubular reactors, fixed-bed reactors, or fluidized bed reactors.