Ethylene is the lightest olefinic hydrocarbon as well as the organic hydrocarbon consumed in the greatest quantity worldwide. It is produced by heating either natural gas, especially its ethane and propane components, or petroleum to 800900 C (1,4701,650 F), giving a mixture of gases from which the ethylene is separated. The melting point of ethylene is 169.4 C [272.9 F], and its boiling point is 103.9 C [155.0 F].Ethylene appears to have been discovered by Johann Joachim Becher, who obtained it by heating ethanol with sulfuric acid he mentioned the gas in his Physica Subterranea (1669).One of the first patents for the commercial production of ethylene is creditedto Union Carbide in 1922. Just three years later, the first commercial plant for ethyleneproduct was built in West Virginia in the United States.Since then, the olefins industry has gradually evolved. Starting with worldscale ethylene plants in the early 1950s with capacities of around 20,000 to 50,000 MTY, plants have become bigger, more energy efficient, and more environmentally friendly. The nameplate capacity for todays worldscale crackers can well be over 1,000,000 MTY of ethylene. Naphtha is the predominate feed for steam crackers, followed by ethane, propane, gas oil, Butane and others.There are several major licensors of conventional commercial olefin technologies, including: Lummus Technology, KBR, Linde, Technip, and the Shaw Group. In addition to the traditional pyrolysis and recovery technologies, new routes to ethylene and propylene production are being developed. These include methanol-to-olefins (MTO), the Fischer-Tropsch process and refinery off-gas recovery.