Technology Type

Process

Ethylene Oxide reacts with Water to produce Ethylene Glycol according to the Chemical Equation:

C₂H₄O + H₂O → HO-CH₂CH₂-OH

This Reaction can be catalyzed by either Acids or Bases, or can occur at neutral pH under elevated Temperatures. The highest Yields of Ethylene Glycol occur at acidic or neutral pH with a large excess of Water. Under these conditions, Ethylene Glycol Yields of 90% can be achieved.

The major byproducts are the Oligomers Diethylene Glycol, Triethylene Glycol, and Tetraethylene Glycol. The separation of these Oligomers and Water is Energy-Intensive.

Yields and Selectivity

A higher Selectivity is achieved by use of Shell's OMEGA Process. In the OMEGA Process, the Ethylene Oxide is first converted with Carbon Dioxide (CO₂) to Ethylene Carbonate. This Ring is then Hydrolyzed with a Base Catalyst in a Second Step to produce Mono-Ethylene Glycol in 98% Selectivity.

For every tonne of ethylene, operators with OMEGA have produced up to 1.95 tonnes of MEG compared with conventional processes which produce between 1.53 tonnes to 1.70 tonnes^[2].

References

1. Wikipedia, Ethylene glycol.
2. Shell, OMEGA process (accessed 29^th Apr 2024).