Ethylene glycol

Ethylene glycol

1. ETHYLENE GLYCOL

2. Ethylene glycol is produced from  ethylene ( ethene ), via the intermediate ethylene oxide . Ethylene oxide reacts with water to produce ethylene glycol according to the chemical equation: C 2 H 4 O + H 2 O → HO–CH 2 CH 2 –OH

3. Ethylene oxide production.  Ethylene and oxygen are fed to a multi-tubular reactor, forming EO. This exothermic reaction, conducted in fixed beds in the reactor tubes, occurs in the gaseous phase with the use of a silver catalyst supported on alumina. Steam is generated by the heat of reaction. Ethylene oxide recovery.  The reactor product stream is fed to the EO absorber for lights removal by water quenching. Part of this gaseous overhead stream is recycled to the reactor, while the other part is sent to a carbon-dioxide-removal unit composed of an absorber and a stripper. In this unit, CO 2  is separated to be used in ethylene carbonate production.

4. Shell OMEGA is the first process to enable ethylene glycol production via a fully catalytic process. According to the licenser, the process is able to achieve EO-to-EG conversion and selectivity near 100%, leading to production of MEG only. A higher selectivity is achieved by use of  this process. In the OMEGA process, the ethylene oxide is first converted with carbon dioxide (CO 2 ) to ethylene carbonate to then react with water in a second step to selectively produce mono-ethylene glycol . The carbon dioxide is released in this step again and can be fed back into the process circuit. The carbon dioxide comes in part from the ethylene oxide production, where a part of the ethylene is completely oxidized.

5. USES Coolant and Heat transfer agent As an anti- freeze or anti- crystallizing agent Pre- cursors to polymers (polyester and polyethylene terephthalate PET) Dehydrating agent.

6. ETHYLENE GLYCOL TOXICITY Ethylene glycol is moderately toxic, with an oral LD Lo  = 786 mg/kg for humans .  The major danger is due to its sweet taste, which can attract children and animals . Upon ingestion, ethylene glycol is oxidized to glycolic acid, which is, in turn, oxidized to oxalic acid, which is toxic . EG and its toxic by-products first affect the central nervous system, then the heart, and finally the kidneys . Ingestion of sufficient amounts can be fatal if untreated.