Liquefied petroleum gas is a kind of petroleum products. The English name is liquefied petroleum gas, or LPG for short. It is a colorless volatile gas obtained by pressurizing, cooling and liquefying refinery gas or natural gas (including oil field associated gas). Liquefied petroleum gas obtained from refinery gas is mainly composed of propane, propylene, butane and butene, and contains a small amount of pentane, pentene and trace sulfur-containing compound impurities. The composition of liquefied gas obtained from natural gas is basically free of olefins. Liquefied petroleum gas (LPG) is mainly used as petrochemical raw materials, for producing ethylene by hydrocarbon cracking or synthetic gas by steam reforming, and can be used as fuel for industry, civil use and internal combustion engines. Its main quality control indicators are evaporation residue and sulfur content, and sometimes olefin content is controlled. Liquefied petroleum gas is a flammable substance. When the content in the air reaches a certain concentration range, it will explode when it meets an open flame.

There are countless organic compounds formed by carbon and hydrogenation in nature, which are usually called hydrocarbons. In organic chemistry, this kind of hydrocarbon is simply called hydrocarbon. Liquefied petroleum gas is a mixture of hydrocarbons with low carbon number. At normal temperature and pressure (20℃, 100KPA), it is gaseous, and it can only become liquid when the pressure increases or the temperature decreases, so it is called liquefied petroleum gas.

The emergence and development of liquefied petroleum gas is closely related to the development of petrochemical industry. 1892, the Netherlands experimented with natural gas for the first time and obtained liquefied methane, which laid a theoretical foundation for the liquefaction of liquefied petroleum gas. At the beginning of the 20th century, Dr. Walter Snelling conducted a stability test on gasoline, and found that the gas volatilized from gasoline was liquid at a certain temperature and pressure, and propane and butane were successfully extracted from natural gas. Subsequently, Germany, the United States, Japan, France, Italy and some countries in Eastern Europe also produced and used LPG. Over the past half century, with the development of petroleum resources and refining and chemical industry, not only countries rich in petroleum resources have developed liquefied petroleum gas rapidly, but also some countries with poor resources have developed liquefied petroleum gas in large quantities. At present, more than 20 countries and regions have produced or imported liquefied petroleum gas by themselves. At present, more than 20 countries and regions have produced or imported liquefied petroleum gas as fuel and chemical raw materials. The annual consumption of liquefied petroleum gas in the United States is about 6000kt, and that in Japan is about 2000kt.

Since 1965, China has begun to use liquefied petroleum gas as civil fuel in cities with developed petrochemical industries such as Beijing, Tianjin, Harbin, Shenyang, Shanghai and Nanjing, as well as in areas where some refineries are located. Since then, major cities have successively built civil supply systems for liquefied petroleum gas. At present, most towns in eastern China and most counties in central China use liquefied petroleum gas, which is gradually popularized in rural areas.