[Chemical Knowledge]：Properties, uses, upstream and downstream raw materials, storage methods, properties and hazards of vinyl chloride

Vinyl chloride properties

Vinyl chloride (chemical formula C2H3Cl), also known as vinyl chloride or vinyl chloride, is a colorless gas with a slightly sweet odor. Its molecular structure contains a vinyl group and a chlorine atom, giving it unique chemical properties. Vinyl chloride is a gas at normal temperature and pressure, but can be liquefied by pressurization or cooling. It has a boiling point of -13.4°C, is denser than air, and is easy to liquefy and transport. Vinyl chloride is flammable and its vapors can form explosive mixtures with air, which can cause fires and explosions under certain conditions, so extreme care should be taken in handling and storage.

Vinyl chloride use

The main use of vinyl chloride is as a monomer for the production of polyvinyl chloride (PVC). PVC is one of the most widely used plastics in the world, widely used in construction, packaging, electrical insulation and other fields. In addition to making PVC, vinyl chloride is also used to make some copolymers and coatings. For example, vinyl chloride is copolymerized with vinyl acetate to produce ethylene-vinyl acetate copolymer (EVA), which is used to make films, adhesives and foams. Vinyl chloride is also used to produce some chemical intermediates, such as vinyl chloride and acetic acid reaction to produce vinyl chloride acetate, used in organic synthesis.

Vinyl chloride upstream and downstream raw materials

The production of vinyl chloride mainly uses ethylene and chlorine as raw materials. Ethylene is an important petrochemical base material, usually obtained from petroleum or natural gas cracking. Chlorine is produced by electrolysis of sodium chloride solution (brine), which also produces hydrogen and sodium hydroxide. Ethylene reacts with chlorine to produce 1,2-dichloroethane (EDC), which is then cracked at high temperatures to produce vinyl chloride and hydrogen chloride. Hydrogen chloride can be recycled and reacted with sodium hydroxide to generate hydrochloric acid, thus realizing the recycling of resources.

Vinyl chloride production process

The industrial production of vinyl chloride mainly uses a two-step method: first, 1,2-dichloroethane (EDC) is generated by the reaction of ethylene and chlorine, and then EDC is cracked into vinyl chloride and hydrogen chloride in a high-temperature cracking furnace. The specific process is as follows: ethylene and chlorine react in the presence of a catalyst (such as ferric chloride or aluminum chloride) to generate EDC, which is an exothermic reaction, and the reaction temperature needs to be controlled to avoid side reactions. After separation and purification, the generated EDC is sent to a cracking furnace and cracked into vinyl chloride and hydrogen chloride at a high temperature (about 500-600 ° C.). Vinyl chloride is cooled and compressed to obtain a liquid product, while hydrogen chloride can be recovered through an absorption tower for other processes.

Vinyl chloride storage method

Since vinyl chloride is a flammable, explosive, and toxic gas, its storage and transportation require special attention. Vinyl chloride is usually stored in liquid form in special high-pressure containers. These containers need to have good sealing and pressure resistance to prevent leakage and explosion. Facilities for storing vinyl chloride should be located away from fire and heat sources, and equipped with necessary ventilation and fire prevention facilities. Vinyl chloride storage tanks and transport containers should be regularly overhauled to ensure that they are in good working condition to avoid accidents caused by equipment aging or damage.

Vinyl chloride safety and environmental protection

Vinyl chloride is toxic, long-term exposure can cause chronic poisoning, and even lead to cancer. Therefore, in the process of production, storage and use, safety operation procedures should be strictly observed, and necessary protective equipment, such as gas masks and protective clothing, should be equipped. The factory should install an effective ventilation system and leak detection device to detect and deal with leaks in time. Vinyl chloride waste gas treatment usually uses combustion method or adsorption method to reduce environmental pollution. The waste liquid and waste residue produced in the production process should also be properly treated to prevent them from entering the water body and soil and causing secondary pollution.

Market Demand and Prospects

With the development of the global economy and the advancement of urbanization, the demand for PVC continues to grow, which in turn drives the demand for vinyl chloride. Especially in developing countries, the expansion of infrastructure construction and real estate market has strong demand for PVC pipes, profiles and other products, thus promoting the development of vinyl chloride industry. On the other hand, with the enhancement of environmental awareness and the improvement of relevant laws and regulations, vinyl chloride production enterprises are also facing the pressure of reducing energy consumption and pollution. Therefore, the future development direction of the vinyl chloride industry will focus on technological improvement, improving production efficiency and environmental protection.

Technological innovation and challenges

The innovation of vinyl chloride production technology mainly focuses on reaction efficiency, energy consumption and environmental protection. For example, the development of new catalysts can improve the reaction rate and selectivity of EDC synthesis, thereby reducing the generation of by-products and reducing energy consumption. Improving the design and operating conditions of the cracking furnace can improve the cracking efficiency and reduce the energy consumption per unit product. The treatment technology of waste gas and wastewater is also an important research direction in the production of vinyl chloride, and the development of efficient and low-cost treatment processes to reduce environmental pollution is an important challenge for the vinyl chloride industry.

Conclusion

As an important chemical raw material, vinyl chloride is widely used in modern industry. It is mainly used in the production of PVC, widely used in construction, packaging, electrical and other fields. The production of vinyl chloride uses ethylene and chlorine as raw materials, and vinyl chloride and hydrogen chloride are obtained by generating EDC and cracking. Due to the toxic, flammable and explosive nature of vinyl chloride, its production, storage and use must strictly comply with safety operating procedures and take effective protective measures. In the future, with the growth of market demand and the improvement of environmental protection requirements, the vinyl chloride industry will face the dual challenges of technological innovation and environmental protection. Through continuous improvement of production technology, efficiency and environmental protection, the vinyl chloride industry will usher in a broader development prospects.