What is Ethylene? Types, Production and Uses

Ethylene (ethene, C₂H₄) is the highest-volume organic chemical produced in the world and the starting point of the petrochemical chain. A very large share of the products we encounter in daily life—from packaging film to pipe, from antifreeze to detergent—are ethylene derivatives. For this reason, ethylene capacity and margin are considered a direct indicator for a country's chemical industry.

What is ethylene?

Ethylene is the simplest alkene, carrying a double bond between two carbon atoms. It is a colorless, faintly sweet-smelling, flammable gas that is lighter than air. It owes its chemical value to this double bond: the double bond opens easily and participates in numerous reactions such as polymerization, oxidation, halogenation and alkylation.

Ethylene is also a plant hormone; it triggers the ripening of fruit. In food logistics, the controlled ripening of products such as bananas and tomatoes relies on this property.

How is it produced?

Nearly all commercial production is carried out via steam cracking. The feedstock—naphtha, ethane, propane or kerosene—is diluted with steam and passed through furnace tubes heated to 800–850°C in under a second. The long-chain molecules break down, the resulting mixture is rapidly cooled, and it is separated into ethylene, propylene, butadiene and aromatics in successive distillation columns.

The choice of feedstock determines the product distribution:

• Ethane-based cracker: high ethylene yield, few by-products. Common in the US and the Middle East thanks to cheap natural gas liquids.
• Naphtha-based cracker: lower ethylene yield but valuable by-products such as propylene, butadiene and aromatics. Dominant in Europe and Asia.

Emerging routes include methanol-to-olefins (MTO), "bio-ethylene" via ethanol dehydration, and electrically heated cracker furnaces (to reduce carbon emissions). Hydrogen and electrification are the topics shaping the agenda in this field.

Derivatives and the usage chain

Roughly two-thirds of total ethylene goes into polyethylene; the remainder is distributed among the intermediate products above.

Which sectors use it?

• Petrochemicals: the first link in the chain; cracker margin determines the profitability of the entire sector.
• Plastics: the basis of polyethylene and PVC production.
• Packaging: food film, bottles and caps.
• Textiles: polyester fiber via ethylene glycol.
• Automotive: antifreeze, cable insulation, interior trim parts.
• Food logistics: controlled ripening.

The Turkish market and production

In Turkey, ethylene production is carried out through Petkim's naphtha cracker in Aliağa; the country is a net importer of polyethylene and other derivatives. This structure directly ties the raw material cost of the domestic plastics processing industry to international ethylene and naphtha prices.

Topics the sector is following include: the cracker margin (the price gap between naphtha and ethylene), capacity investments, the impact of the Carbon Border Adjustment Mechanism on exports, and chemical recycling efforts to produce monomers again from waste plastic. You can find current news on ethylene prices and the supply-demand balance below.

Technical specifications

A critical temperature of around 9°C means that ethylene cannot be liquefied by pressure alone at room temperature—this is why storage is cryogenic. The wide flammability range and low ignition energy make sealing, ventilation and ignition source control decisive factors in plant design. For polymerization quality, the purity of ethylene (keeping catalyst poisons such as acetylene, oxygen and sulfur compounds at ppm levels) is a critical quality parameter.

Points to watch in supply and market monitoring

• Track it as a margin, not just a price. It is not the ethylene price itself but the spread against naphtha that determines the producer's profitability.
• Distinguish between regional benchmarks. Northwest Europe, US Gulf Coast and Northeast Asia quotations reflect different feedstock bases; using one in place of another is misleading.
• Keep track of maintenance shutdowns. Cracker turnarounds predictably tighten supply and affect contract timing.
• Factor in logistics constraints. Cryogenic transport and limited terminal capacity restrict spot purchase flexibility independent of price.
• Monitor carbon regulations. For derivative producers that export, the embedded carbon of the product is increasingly becoming part of the price.

Frequently asked questions

Why is ethylene considered the "key molecule of petrochemicals"?

Because it is the organic chemical with the highest production volume and the common starting point for numerous value chains. Products as different from one another as polyethylene, PVC, PET and polystyrene are all derived from ethylene. For this reason, ethylene capacity is a fundamental indicator of the scale of a country's chemical industry.

What is the difference between an ethane cracker and a naphtha cracker?

An ethane cracker produces almost exclusively ethylene and has low operating costs; it is advantageous in regions with cheap natural gas liquids. A naphtha cracker yields less ethylene but also produces propylene, butadiene and aromatics. If demand for these by-products is high, a naphtha cracker can be more profitable overall.

What is bio-ethylene, and is it different from fossil-based ethylene?

Bio-ethylene is produced through the dehydration of bioethanol. As a molecule, it is exactly identical to fossil-based ethylene; there is no difference in product performance. The only difference is in carbon footprint, which is documented through certification. Its cost is currently higher than the fossil route.

Can ethylene be stored?

Ethylene is a gas at room temperature and has a low critical temperature; therefore it is liquefied at around −104°C and stored in cryogenic tanks. Specialized ethylene carriers are used for long-distance transport. This difficulty is the main reason why cracker facilities are usually built right next to derivative plants.

Are ethylene and ethanol confused with each other?

They are different substances. Ethylene is an alkene (C₂H₄), while ethanol is an alcohol (C₂H₅OH). There is an industrial link between them: ethylene can be converted to ethanol through hydration, and ethanol can be converted to ethylene through dehydration. Which direction is economical depends on regional feedstock prices.