Safe point-of-use Ethylene Oxide production

Start date January 2020

Client University of Cambridge

Dr David Nugent



Researchers in the Department of Engineering and the Department of Chemical Engineering, University of Cambridge, have developed a new catalyst and process for the generation of ethylene oxide from ethene which removes the need for purified air, showing a potential new route to more efficient and safer ethylene oxide (EtO) production. Candidate applications include point-of-use EtO production for sterilisation and specialist chemical production.

Anaerobic epoxidation and EtO production

Ethylene oxide is an industrially-significant chemical intermediate, with a global production of 26 million tonnes in 2013. Its primary uses are as a sterilant for temperature-sensitive medical devies and the synthesis of polymers, antifreeze, surfactants, solvents, etc. The predominant technology for its production is the epoxidation of ethylene with air or purified oxygen. Silver is the only catalyst used because no other material matches its performance.

The principles of the anaerobic epoxidation of ethylene are summarised below. In Step 1, ethylene is oxidised using oxygen gas released from a catalyst comprising silver supported on SrFeO3. Absent from the input gas, oxygen arises solely from the catalyst bed. In Step 2, the reactor is purged with inert gas such as nitrogen or by-product CO2. In Step 3, the catalyst is regenerated by passing purified air through the reactor bed.

Crucially, EtO is produced by the oxidation of ethylene delivered and stored in non-flamable nitrogen mixtures. Provided extraction and ventilation is available for discharging product gases, this means EtO can be produced safely on-demand without the hazards associated with transportation and storage of this highly explosive and toxic substance. 

Chemical looping epoxidation

Conceivably epoxidation and EtO production could proceed in a semi-continuous manner using the alternating regeneration-oxidation reaction shown below. Similar batchwise gas reactions are used in applications such as amine scrubbing.

Chemical looping epoxidation



Documents available for download

Anaerobic Epoxidation of Ethylene: Safe, efficient ethylene oxide production

Chemical looping epoxidation
Published PCT patent application