Ethylene oxide: Production route
A silver catalyst and a race against burning
What this tab covers How it is made: the main production routes or, for product families, the main product types and technologies, compared on share of supply, inputs per tonne, plant scale, yield, co-products and unit cost.Nearly all EO is made by direct oxidation of ethylene with oxygen over a silver catalyst, using licensed technology from Shell (CRI), Dow (Univation/Meteor), Scientific Design or Sinopec. Older air-based plants and the obsolete chlorohydrin route survive only in a few places. The key differences between plants are catalyst selectivity, which sets ethylene use and CO2 output, and whether EO is sold as purified EO or converted to glycols.
Routes compared
| Route | Share of supply | Inputs per tonne | Typical scale | Yield | Co-products | Unit cost |
|---|---|---|---|---|---|---|
| Oxygen-based direct oxidation (with glycols) | over 95% of global capacity (indicative) | about 0.75 t ethylene and 0.7 t oxygen per t EO (indicative) | 200-1,000 kt/yr EO; e.g. Sinopec Zhenhai No. 2 EO 200 kt with EG 800 kt (Argus) | selectivity 85-90% (indicative) | CO2 about 0.3-0.4 t per t EO; steam | ethylene is about 75-85% of cash cost (indicative) |
| Air-based direct oxidation | small, declining (indicative) | about 0.8-0.9 t ethylene per t EO (indicative) | older units 50-200 kt/yr | selectivity 70-80% (indicative) | more CO2 | higher than oxygen route |
| Purified EO for derivatives and sterilisation | about 30% of EO output (indicative) | same as above plus distillation steam | 50-300 kt/yr purified EO | n/a | none | Europe purified EO contract €1,294/t (Oct 2025); US 56.20 c/lb (about $1,239/t, Aug 2025) (Argus) |
How each route works
Oxygen-based direct oxidation (with glycols)Ethylene, oxygen and methane ballast circulate over a silver catalyst in multitubular reactors at 220-280°C and 1-3 MPa. EO is absorbed in water, then either purified or hydrolysed to MEG. CO2 is removed in a carbonate loop.
Mature and efficient, but process CO2 is inherent and EO is hazardous.
Argus Oct 2025; indicative (industry standard) Air-based direct oxidationOlder variant using air instead of pure oxygen; lower selectivity and a vent stream of nitrogen.
No ASU needed, but wastes ethylene.
indicative Purified EO for derivatives and sterilisationPart of reactor EO is distilled to 99.9% and sold to ethoxylation, ethanolamine and sterilisation users, usually within a few hundred kilometres.
Higher value, but logistics and safety limit reach.
Argus Oct 2025 Unit economics are indicative ranges from the sources named; costs move with feedstock and energy prices, plant size and region.