Petrochemical industry refers to the industry using petroleum as raw materials to produce industrial chemicals, also including natural gas chemical industry. The petrochemical industry is an emerging industry and has emerged together with the development of oil refining industry since the 1920s. After World War II, large number of chemical raw materials and products began to use petroleum and natural gas as raw materials instead of using original coal and its by-products as raw materials, making petrochemical industry having become the basis for the chemical industry, occupying a very important position in the national economy. The petrochemical raw materials are mainly those various kinds of petroleum distillates and refinery gas as well as oil field gas and natural gas. After the 1970s, petroleum chemical industry had established a complete set of technical system with the products having been applied to various fields including national defense, national economy and people's lives. The international society commonly used the production amount of ethylene, plastics, synthetic fibers, synthetic rubber and other major products to measure the level of development of petrochemical industry. Since petrochemical industry can create higher economic efficiency, it has become fundamental basis for industrial countries. In modern times, in order to improve the economic efficiency, the major measures that petrochemical enterprises adopt are: make the raw materials for ethylene production be diverse, having the hydrocarbon cracker own the flexibility for adapting to a various kinds of raw materials; the overall structure of the petrochemical are more closely related to that of oil refining, make full use of technology; improvements of technology processes and the application of new catalysts has increased the product yield and reduced the consumption of raw materials and energy; adjust the product structure, develop fine chemicals and develop novel products and materials of special performance and being technology-intensive. The environmental contamination problem of the petrochemical production had also gotten gradually solved.
Petrochemicals
Petrochemical product refers to the products manufactured using petroleum or petroleum gas as raw materials. There are up to thousands kinds of petrochemical products, of which the most important are the six fundamental raw materials (ethylene, propylene, butene, benzene, toluene, xylene).
In China, there are 57 kinds of Class 7 in total. Class 1 belongs to organic material and there are 16 kinds including ethylene, benzene and methanol. Class 2 is a kind of synthetic resin, there are 12 kinds including low-density polyethylene, polypropylene, etc., in 2001, the production capacity is nearly 5.05 million tons. Class 3 is synthetic rubber, containing five kinds including butadiene. In 2001, its production capacity is 684,600 t. Class 4 is synthetic fiber with the production amount in 2001 being nearly 7.6 million tons. There are six kinds, namely polyester, nylon, acrylic fibers, polyvinyl alcohol, polypropylene, and PBT fibers. Class 5 refers to fine chemicals, being one of the symbols of the country's comprehensive technical level. It has accounted for 55% to 65% of the total output value of chemical industry in developed country while this value is only 35% in China. The main products include catalysts, surfactants, synthetic detergent, etc, around 10 kinds in total. Class 6 is fertilizer, including nitrogen, phosphorus, potassium fertilizer three kinds. People mainly produce and synthesize fertilizer such as ammonia and urea with the production capacity of these two products in 2001 being 2.93 million and 4.62 million tons, respectively. Class 7 refers to inorganic material, that is, three acids and two alkaline, five in total.