是化学工业的重要组成部分，在国民经济的发展中有重要作用，是我国的支柱产业部门之一。石油化工指以石油和天然气为原料，生产石油产品和石油化工产品的加工工业。石油产品又称油品，主要包括各种燃料 油（汽油、煤油、柴油等）和润滑油以及液化石油气、石油焦碳、石蜡、沥青等。生产这些产品的加工过程常被称为石油炼制，简称炼油。石油化工产品以炼油过程提供的原料油进一步化学加工获得。生产石油化工产品的第一步是对原料油和气（如丙烷、汽油、柴油等）进行裂解，生成以乙烯、丙烯、丁二烯、苯、甲苯、二甲苯为代表的基本化工原料。第二步是以基本化工原料生产多种有机化工原料（约200种）及合成材料 （塑料、合成纤维、合成橡胶）。这两步产品的生产属于石油化工的范围。有机化工原料继续加工可制得更多品种的化工产品，习惯上不属于石油化工的范围。在有些资料中，以天然气、轻汽油、重油为原料合成氨、尿素，甚至制取硝酸也列入石油化工。 Is an important part of the chemical industry, have an important role in the development of the national economy, it is one of China's pillar industries. Petrochemical refers to the oil and natural gas as raw materials, production of petroleum products and petrochemical products processing industry. Petroleum products, also known as oil, including a variety of fuels Oil (gasoline, kerosene, diesel, etc.) and lubricants and liquefied petroleum gas, petroleum coke, paraffin, asphalt. Process to produce these products are often referred to as petroleum refining, refining referred. Feedstock for further chemical processing of petrochemical products to provide access to the refining process. The first step in the production of petrochemical products is the raw material oil and gas (such as propane, gasoline, diesel, etc.) cleavage, generates ethylene, propylene, butadiene, benzene, toluene, xylene, represented by the basic chemical raw materials. The second step is a basic chemical raw materials to produce a variety of organic chemical raw materials (about 200 species) and synthetic materials (plastics, synthetic fibers, synthetic rubber). This two-step products within the scope of petrochemicals. Organic chemical raw materials continue processing can be obtained more varieties of chemical products, the habit does not belong to the scope of petrochemicals. In some materials, natural gas, light gasoline, heavy oil as raw material ammonia, urea, nitric acid is also included in the preparation even petrochemicals.