How Acrylonitrile is Made

How Acrylonitrile is Made: A Comprehensive Analysis from Raw Material to Production Process

Acrylonitrile (Acrylonitrile, referred to as AN) is an important organic chemical raw material, which is widely used in the production of synthetic fibers, rubber, plastics and chemicals. As a basic chemical raw material, the production process of acrylonitrile involves multiple chemical reactions and process steps, and is usually produced by extracting and transforming from petrochemical raw materials. Acrylonitrile is how to manufacture? This paper will analyze this problem in detail from the aspects of raw materials, production process and environmental impact.

1. acrylonitrile production raw materials

The main raw materials of acrylonitrile are propylene, ammonia and oxygen. Acrylonitrile production is usually accomplished by a gas phase reaction process in which propylene provides the carbon source, ammonia as the nitrogen source, and oxygen participates in the oxidation reaction. The choice of these raw materials directly affects the quality and yield of the final product, so reasonable raw material selection and preparation is essential.

1. Propylene: propylene is through the oil or natural gas refining process of light olefins, it is acrylonitrile synthesis reaction of the key raw materials.
2. Ammonia: ammonia is generally obtained by natural gas ammonia synthesis method, in the reaction process as a nitrogen source to participate in the synthesis reaction.
3. Oxygen: Oxygen in the reaction provides an oxidizing environment, which helps to improve reaction selectivity and reaction efficiency.

2. acrylonitrile synthesis process

The core of how acrylonitrile is manufactured lies in its synthesis process. At present, the production of acrylonitrile mainly adopts "propylene ammoxidation method" (AA oxidation method for short). In this process, propylene, ammonia and oxygen are reacted in gas phase under certain conditions, and acrylonitrile is finally synthesized. The specific process is as follows:

1. Gas phase reaction in the reactor: After propylene, ammonia and oxygen enter the reactor, the oxidation reaction takes place at a high temperature (about 350°C to 400°C) and a certain pressure. During the reaction, oxygen participates in the oxidation of propylene, and ammonia as a nitrogen source reacts with the oxide to produce acrylonitrile.

2. The role of the catalyst: The reaction usually requires the participation of a catalyst, and the commonly used catalysts are molybdenum-based or tungsten-based catalysts. The catalyst can not only increase the reaction rate, but also improve the selectivity of the product and reduce the formation of by-products.

3. Product separation and purification: The mixed gas obtained after the reaction contains acrylonitrile, ammonia, propylene and some by-products. Acrylonitrile is separated and purified by processes such as cooling, absorption and fractionation. Finally, the purity can reach more than 99%, which meets the requirements of industrial applications.

3. acrylonitrile by-product and its treatment

In the production process of acrylonitrile, due to the complex reaction conditions, some by-products are often generated. These by-products may have an impact on the environment and equipment, so they need to be controlled through a series of treatment measures.

1. Nitrogen oxides (NOx): Since oxygen and ammonia are involved in the reaction, part of the ammonia may be oxidized at high temperatures to form nitrogen oxides. These gases are harmful to the environment and are usually treated by techniques such as selective catalytic reduction (SCR).

2. Separation of by-products: In addition to nitrogen oxides, undesired olefins or ketones may also be formed in the reaction. These by-products are separated from acrylonitrile using techniques such as condensation and adsorption to improve the purity of the final product.

3. Environmental protection measures: modern acrylonitrile production plants are usually equipped with waste gas treatment systems, such as gas absorption towers, catalytic oxidation units, etc., to ensure that the production process will not cause serious pollution to the environment.

4. acrylonitrile applications

As an important chemical raw material, acrylonitrile has a wide range of applications. Its main uses include:

1. Synthetic fiber production: Acrylonitrile is a key raw material for the manufacture of Acrylic fiber and other synthetic fibers. These fibers are widely used in clothing, carpets and household goods.

2. Synthetic rubber: Acrylonitrile is also used in the production of synthetic rubber, especially in synthetic nitrile rubber. Acrylonitrile provides the rubber with oil resistance and high temperature resistance.

3. Plastics and chemicals production: Acrylonitrile is an important basic raw material for the manufacture of acrylic acid, cyano chemicals and other plastics.

Conclusion

Through the analysis of how acrylonitrile is manufactured, we can see that the production process of acrylonitrile involves many key links, including raw material preparation, synthesis reaction, product separation and purification, and environmental protection. With the continuous development of technology, the production process of acrylonitrile is constantly optimized to improve production efficiency, reduce energy consumption and reduce environmental pollution. Understanding the manufacturing process of acrylonitrile not only helps the industry to master the production technology, but also helps to improve the overall understanding of this important chemical raw material.