[Chemical Knowledge]：phthalic acid properties, uses, upstream and downstream raw materials, storage methods, phthalic acid toxic?

Phthalic acid properties

Phthalic acid (Phthalic Acid), chemical formula C8H6O4, is an important organic acid. Its appearance is white crystalline powder, hygroscopic and acidic. Phthalic acid has a melting point of around 208°C and a boiling point of 284°C. It is slightly soluble in water, but soluble in ethanol, ether and other organic solvents. In industry, phthalic acid is mainly produced by oxidation of o-xylene (o-Xylene). Phthalic acid is easily decomposed into phthalic anhydride (Phthalic Anhydride) at high temperature.

Phthalic Acid Uses

Phthalic acid is widely used in many industries, the main use is for the production of phthalate plasticizers. Plasticizers are important additives in the plastics industry, which can increase the flexibility and durability of plastics. In addition to being an intermediate for plasticizers, phthalic acid is also used in the manufacture of chemical products such as dyes, pigments, pharmaceuticals and pesticides. Its derivatives also have important applications in the production of polyester resins and unsaturated polyester resins. Phthalic acid is also used as a standard reagent in some analytical chemistry.

Phthalic acid upstream raw materials

The main upstream feedstock for phthalic acid is o-xylene (o-Xylene). Ortho-xylene is an important petrochemical product obtained through fractionation and reforming processes in petroleum refining. In industrial production, o-xylene is first oxidized to phthalic anhydride and then hydrolyzed to phthalic acid. The production process also requires the use of oxygen and catalysts, such as vanadium oxide catalysts, to improve the efficiency and yield of the reaction.

Phthalic acid downstream products

The downstream products of phthalic acid are mainly phthalate plasticizers, such as dibutyl phthalate (DBP) and dioctyl phthalate (DOP). These plasticizers are widely used in plastic products such as PVC and polyethylene to increase their flexibility and durability. Derivatives of phthalic acid are also used in the manufacture of unsaturated polyester resins, alkyd resins, dyes and pigments, etc. In the field of medicine, phthalic acid is also an intermediate in the synthesis of certain drugs, such as antibiotics and analgesics.

Phthalic acid storage method

Because phthalic acid is hygroscopic and acidic, it requires special attention during storage. Phthalic acid should be stored in a dry, cool place, avoid contact with moisture, to prevent its caking and hydrolysis. The storage container should be well sealed and use anti-corrosion materials to prevent it from reacting with moisture and other chemicals in the air. For safety reasons, the storage area should have good ventilation conditions and be away from fire and high temperature environment. Personnel handling phthalates should wear protective equipment to avoid inhalation of dust or contact with skin.

Phthalic acid production process

The production of phthalic acid usually uses o-xylene oxidation method. The process flow of this method includes: mixing o-xylene with air, generating phthalic anhydride through high-temperature oxidation reaction, and then obtaining phthalic acid through hydrolysis reaction. In actual production, in order to improve the reaction efficiency and product quality, vanadium oxide is usually used as a catalyst, and the reaction temperature and pressure are controlled. In the production process, by-products such as water and carbon dioxide need to be separated and purified to ensure the purity of the product and the safety of the environment.

Phthalic Acid Environmental Impact

Phthalic acid may have a certain impact on the environment in the process of production and use. In particular, their derivatives, phthalate plasticizers, have been found to pose potential environmental and health risks. These plasticizers may be released into the environment during use, contaminate water and soil, and cause harm to ecosystems. In order to reduce the environmental impact, the industry is gradually using environmentally friendly plasticizers, such as cyclohexanedicarboxylic acid ester (DINCH) to replace phthalates. In the production process, the treatment and management of waste water and waste gas should be strengthened to ensure the discharge standard.

Phthalic Acid Market Prospects

With the continuous development of the global plastics industry and chemical industry, the market demand for phthalic acid and its derivatives will continue to grow. Driven by environmental regulations and market demand for green products, traditional phthalate plasticizers are gradually being replaced by environmentally friendly plasticizers. In the future, the market prospect of phthalic acid will depend on its application innovation in new materials, new processes and environmental protection. Manufacturers need to continuously improve technology, improve product quality, and reduce production costs to respond to market competition and policy changes.

Conclusion

As an important organic acid, phthalic acid is widely used in chemical industry. By understanding its nature, use, upstream and downstream raw materials and storage methods, we can better understand its role and impact in industrial production. With the enhancement of environmental awareness and technological progress, the production and application of phthalic acid and its derivatives will face new challenges and opportunities. Production enterprises need to actively respond to promote green development and ensure the sustainable development of the industry.