The OMEGA process ("Only MEG Advantage")
is a chemical process discovered by the
Shell Global Solutions company that is used to produce
ethylene glycol
Ethylene glycol ( IUPAC name: ethane-1,2-diol) is an organic compound (a vicinal diol) with the formula . It is mainly used for two purposes: as a raw material in the manufacture of polyester fibers and for antifreeze formulations. It is an odo ...
from
ethylene
Ethylene (IUPAC name: ethene) is a hydrocarbon which has the formula or . It is a colourless, flammable gas with a faint "sweet and musky" odour when pure. It is the simplest alkene (a hydrocarbon with carbon–carbon bond, carbon–carbon doub ...
. This process comprises two steps, the controlled oxidation of ethylene to
ethylene oxide
Ethylene oxide is an organic compound with the chemical formula, formula . It is a cyclic ether and the simplest epoxide: a three-membered ring (chemistry), ring consisting of one oxygen atom and two carbon atoms. Ethylene oxide is a colorless ...
, and the net hydrolysis of ethylene oxide to
monoethylene glycol (MEG).
The first chemical plant using the OMEGA process was started in South Korea. Subsequent OMEGA plants have been started in Saudi Arabia and Singapore.
Shell claims that this process, compared to conventional ones, does not produce higher glycols, uses less steam and water, and generates less waste.
[
]
Ethylene oxidation
To produce ethylene oxide, ethylene is oxidized with dioxygen in the presence of a silver catalyst. Some ethylene is over-oxidized to carbon dioxide and water, which is wasteful; early processes only gave ~ 65% selectivity for ethylene oxide as a result. In the OMEGA process, over-oxidation is reduced by including ethyl chloride as a moderator.[
]
Ethylene oxide hydrolysis
Conventionally, monoethylene glycol (HOC2H4OH) is produced by the controlled hydrolysis of ethylene oxide (C2H4O). The monoethylene glycol product is also able to react with ethylene oxide to give diethylene glycol
Diethylene glycol (DEG) is an organic compound with the formula (HOCH2CH2)2O. It is a colorless, practically odorless, and hygroscopic liquid with a sweetish taste. It is a four carbon Dimer (chemistry), dimer of ethylene glycol. It is miscible in ...
, and so on; sequential reaction with ethylene oxide is how poly(ethylene glycol) is produced. Due to monoethylene glycol's high boiling point, purification by distillation is energy intensive.
: C2H4O + H2O → HOC2H4OH
In the OMEGA process, the ethylene oxide reacts with carbon dioxide
Carbon dioxide is a chemical compound with the chemical formula . It is made up of molecules that each have one carbon atom covalent bond, covalently double bonded to two oxygen atoms. It is found in a gas state at room temperature and at norma ...
(CO2) to yield ethylene carbonate
Ethylene carbonate (sometimes abbreviated EC) is the organic compound with the formula (CH2O)2CO. It is classified as the cyclic carbonate ester of ethylene glycol and carbonic acid. At room temperature (25 °C) ethylene carbonate is a tra ...
(C3H4O3). Ethylene carbonate is subsequently hydrolyzed to monoethylene glycol and carbon dioxide. The carbon dioxide is released in this step again and can be fed back into the process circuit. This process is 99.5% selective for monoethylene glycol.[
: C2H4O + CO2 → C3H4O3
: C3H4O3 + H2O → HOC2H4OH + CO2
This part of the OMEGA process was originally developed by Mitsubishi Chemicals, and it has been exclusively licensed to Shell.][
]
See also
* Carbonate ester
References
{{Reflist
Chemical processes
Carbonate esters
Diols