Steam cracking

Steam cracking is a high-temperature process that breaks hydrocarbons into smaller molecules, especially ethylene and propylene. It uses steam to dilute the feed and limit unwanted reactions.

Pyrolysis: The thermal decomposition of materials in the absence of sufficient oxygen for combustion. Steam cracking is the industrial hydrocarbon form of this broader thermal decomposition.
Ethane: A two-carbon saturated hydrocarbon with the formula C₂H₆. Ethane is a light feedstock that cracks selectively toward ethylene.
Polyethylene: A widely used polymer made by linking ethylene molecules into long chains. Steam-cracked ethylene is a primary feedstock for polyethylene production.
Fluid catalytic cracking: A refinery process that uses a circulating catalyst to convert heavy oil fractions into lighter products. It cracks heavier feeds catalytically, unlike the high-temperature, noncatalytic furnace reactions here.
Free-radical reaction: A chemical reaction involving species with unpaired electrons, often proceeding through chain steps. Radical chains drive the bond breaking and molecule formation in cracking furnaces.
Naphtha: A liquid petroleum fraction containing hydrocarbons of varied molecular sizes, commonly used as a petrochemical feedstock. Naphtha yields a broader product mixture than ethane, including several valuable olefins.
Polypropylene: A thermoplastic polymer made from propylene, used in packaging, fibers, and durable goods. Steam-cracked propylene feeds the production of this major commodity plastic.
Catalytic cracking: The breakdown of large hydrocarbon molecules using catalysts to lower reaction barriers and steer products. Catalysts distinguish this family of routes from steam cracking's thermal radical chemistry.
Steam dilution: The addition of steam to a hydrocarbon feed to lower its partial pressure during processing. Dilution suppresses secondary reactions and reduces coke formation in the furnace.
Ethylene: The two-carbon alkene C₂H₄, a major chemical building block and polymer feedstock. It is the principal product sought from many steam-cracking operations.

Linked from 14 pages