Olefins, also called alkenes, are unsaturated organic compounds that contain at least one carbon-to-carbon double bond. They can be used in many reactions which occur by opening up the double bond.
Olefins are used as building block chemicals for making other petrochemicals and polymers. The commercially most important olefins are ethylene, propylene and butadiene. Other olefins used in the production of petrochemicals and polymers include butene, isobutene (or isobutylene), hexene and octene.
Ethylene is the largest volume olefin used in the manufacture of polymers such as polyethylene (PE), polyester, polyvinyl chloride (PVC) and polystyrene (PS). The main intermediate chemicals produced from ethylene include ethylene oxide and ethylene glycol, ethylene dichloride (EDC) and vinyl chloride monomer (VCM), ethylbenzene and styrene, vinyl acetate monomer (VAM), alpha olefins and industrial ethanol. These products are used in a wide variety of industrial and consumer markets such as the packaging, transportation, electronic, textile and construction industries.
Propylene consumption is dominated by polypropylene (PP), which accounts for 60% of global consumption. Injection moulding is the largest PP market but it can also be made into fibres, film and sheet and extruded into pipe and conduit. Other important derivatives of propylene are acrylonitrile (ACN), oxo alcohols, propylene oxide, cumene and acrylic acid. Propylene has been the fastest growing of the three main olefins, mainly due to the strong demand for polypropylene.
Butadiene is a versatile raw material used in the production of a wide variety of synthetic rubbers/elastomers and polymer resins as well as a few chemical intermediates. The largest uses for butadiene are the production of styrene butadiene rubber (SBR) and polybutadiene rubber (BR), which are used mainly in tyres and other automotive products. Butadiene is one of the components used in the manufacture of acrylonitrile-butadiene-styrene (ABS), styrene-butadiene (SB) copolymer latex, styrene-butadiene block copolymers and nitrile rubbers.
Olefins are manufactured primarily by the steam cracking of petroleum-based products such as naphtha, gas oil, ethane, propane and butane. Propylene can also be sourced from fluid catalytic crackers in refineries and by on-purpose technologies such as propane dehydrogenation and metathesis. Methanol-based processes to make ethylene and propylene are being developed.