[Chemical Knowledge]：The nature, use, upstream and downstream raw materials, storage methods, flash point of isomeric xylene? What is the ignition point?

Isomeric Xylene Properties

Isomeric xylene (Isomeric Xylene) is a class of aromatic hydrocarbons, including o-xylene (o-Xylene), m-xylene (m-Xylene) and p-xylene (p-Xylene) three isomers. Their chemical formula is C8H10, and their molecular structure contains a benzene ring and two methyl substituents. Due to the existence of benzene ring, isomeric xylene has high chemical stability and aromaticity. The physical properties of each isomer are slightly different: o-xylene has a boiling point of 144°C, m-xylene has a boiling point of 139°C, and p-xylene has a boiling point of 138°C. They have a density of about 0.86g/cm³ and are insoluble in water, but are miscible with most organic solvents.

Isomeric xylene use

Isomeric xylene is widely used in chemical, pharmaceutical, dye and resin industries. Para-xylene (p-Xylene) is an important raw material for the production of terephthalic acid (PTA), which is further used in the production of polyethylene terephthalate (PET), a common polyester fiber and plastic bottles. m-xylene (m-Xylene) is used in the preparation of isophthalic acid (isophthalic acid), which is mainly used in the production of high-performance coatings and unsaturated polyester resins. Ortho-xylene (o-Xylene) is mainly used in the production of phthalic anhydride (phthalic anhydride), used in the manufacture of plastic plasticizers, coatings, dyes and synthetic resins.

Upstream raw materials

The production of isomeric xylenes is mainly dependent on the oil and coal industries. In the process of petroleum refining, the aromatic fraction produced by reforming reaction is an important source of isoxylene. Aromatic reforming processes convert long-chain hydrocarbons into aromatic hydrocarbons through hydrocracking and catalytic reforming. The coking process in the coal industry also produces small amounts of isomeric xylenes. With the progress of petrochemical technology, the development of catalytic reforming and selective cracking technology, the efficiency and purity of the production of isomeric xylenes are continuously improved.

Downstream Products

The downstream products of isomeric xylenes are very extensive. Terephthalic acid (PTA) is one of the most important downstream products. It is an important raw material for the manufacture of PET, which is widely used in fibers, plastic bottles and packaging materials. Phthalic anhydride (PA) is mainly used in the production of plasticizers, coatings and dyes. Isophthalic acid (IA) is used in the manufacture of high performance coatings and resins. Isomeric xylene itself is also an important solvent, widely used in coatings, inks, pesticides and pharmaceuticals and other industries.

storage method

Isomeric xylenes are volatile and flammable, so their storage must comply with strict safety regulations. Generally, isomeric xylenes are stored in specially designed steel storage tanks. These tanks should have good sealing and corrosion resistance, and be equipped with pressure relief devices and fire protection systems. The storage environment should be kept well ventilated, away from fire and high temperature areas. In order to prevent volatilization loss and air pollution, a recovery device is usually installed on the top of the storage tank to capture and recover volatile gases. The storage area shall be equipped with emergency sprinkler system and fire extinguishing equipment to deal with sudden accidents.

Environmental and safety considerations

Environmental and safety issues are of great importance in the production, storage and use of isomeric xylenes. The volatility and toxicity of isomeric xylenes are potentially harmful to the environment and human health. Therefore, the factory must be equipped with waste gas treatment equipment in the production process to reduce the emission of volatile organic compounds (VOCs). Wastewater treatment facilities should also ensure that wastewater discharge standards, to avoid water pollution. For operators, necessary personal protective equipment, such as protective gloves, masks and goggles, should be provided, and regular safety training should be conducted. Regular equipment maintenance and safety inspection is the key to prevent accidents.

Economic and market outlook

With the development of the global economy, especially the acceleration of industrialization in developing countries, the demand for isomeric xylene is increasing. The widespread use of PET plastics and polyester fibers has driven the demand for terephthalic acid, which in turn has driven the demand for p-xylene. In recent years, the increasingly stringent environmental regulations have prompted enterprises to continuously improve the production process and improve the production efficiency and environmental protection level of heterogeneous xylene. In the future, with the progress of technology and the change of market demand, the market of isomeric xylene will continue to grow steadily.

Conclusion

Isomeric xylene, as an important chemical raw material, has a wide range of applications and good market prospects. Its production depends on the upstream raw materials of the oil and coal industries, and the main downstream products include terephthalic acid, phthalic anhydride and isophthalic acid. The storage and use of isomeric xylenes requires strict compliance with safety and environmental regulations to prevent accidents and pollution. With the advancement of technology and the growth of market demand, the heterogeneous xylene industry will usher in more development opportunities and provide important support for related industries.