Ethylene oxide
A reactive, toxic gas made by oxidising ethylene over silver; the gateway to glycols for polyester, surfactants, ethanolamines and sterilisation.
Commodity chemicals · Derivatives & intermediates · No. 36
- Single chemical
- Feedstock: Oil, gas or coal
- about 33-35 Mt produced a year (2025, indicative: about 40 Mt capacity x about 85%)
- 1.9 t CO₂e per t
- HS 291010
A gas that can burn with no air at all is also the chemical that sterilises your hospital's syringes.
Chart: Illustration: Ethylene oxide
Where it comes from
Chart: Map of where it comes from
Ethylene and pure oxygen circulate over silver catalyst at 220-280 C. Modern catalysts are 85-90% selective; the rest of the ethylene burns to CO2 and water.
Three things to know
- About 70% of ethylene oxide never leaves the site as EO; it is turned into glycols for polyester straight away.
- EO can burn in mixtures from 3% to 100% in air, so tanks are blanketed with nitrogen and kept cold.
- US rules from 2024 aim to cut EO emissions at commercial sterilisers by about 90%.
The journey
- 1 Ethylene, oxygen0.75 t ethylene, 0.7 t oxygen
- 2 Silver catalystOxidised at 220-280 C
- 3 CO2 removalCarbonate wash strips near-pure CO2
- 4 Derivative unitMost hydrated straight into glycols
- 5 ProductsPolyester glycols, detergents, amines, sterilants