It is an important part of the chemical industry and plays an important role in the development of the national economy. It is one of the pillar industries of China. Petrochemical refers to the processing industry that produces petroleum products and petrochemical products by using oil and natural gas as raw materials. Petroleum products, also known as oil products, mainly include various fuel oils (gasoline, kerosene, diesel, etc.) and lubricating oils, as well as liquefied petroleum gas, petroleum coke, paraffin, and asphalt. The process of producing these products is often referred to as petroleum refining, or simply refining. Petrochemical products are further chemically processed from feedstock oil supplied by the refining process. The first step in the production of petrochemical products is to crack the feedstock oil and gas (such as propane, gasoline, diesel, etc.) to form basic chemical raw materials represented by ethylene, propylene, butadiene, benzene, toluene and xylene. The second step is to produce a variety of organic chemical raw materials (about 200 kinds) and synthetic materials (plastic, synthetic fiber, synthetic rubber) from basic chemical raw materials. The production of these two products belongs to the scope of petrochemical industry. The continuous processing of organic chemical raw materials can produce more varieties of chemical products, and it is not customary to fall within the scope of petrochemical industry. In some materials, the synthesis of ammonia, urea, and even nitric acid from natural gas, light gasoline, and heavy oil are also included in petrochemicals.