Glycols

Tri Ethylene Glycol

Tri ethylene glycol (also known as TEG, triglycol and trigen) is a colourless, viscous, non-volatile liquid with the formula C6H14O4.  It is well known for its hygroscopic quality and its ability to dehumidify fluids.

Production

Tri ethylene glycol is prepared commercially as a co-product of the oxidation of ethylene at high temperature, in the presence of a silver oxide catalyst.  The ethylene oxide is then hydrated to yield mono, di, tri, and tetra ethylene glycols.

It is estimated that the total world consumption of TEG is in excess of 175 metric tonnes annually.

Storage and Distribution

Tri ethylene glycol can be stored and transported in stainless steel, aluminium  or lined tank cars, tank trucks, or 225 kg drums.  It has a specific gravity of 1.125 and a flash point of 168 °C (closed cup) and is not classified for transport by road, sea, or rail.

Uses

The main uses for tri ethylene glycol are based upon its hygroscopic quality.  It is used as a dehydrating agent for natural gas pipelines where it removes the water from the gas before being condensed and reused in the system.  It is also a dehumidifying agent in air-conditioning units.

It is also used to make chemical intermediates such as plasticisers and polyester resins.  It is an additive in hydraulic fluids and brake fluids, and TEG is also used as a solvent in many applications, including as a selective solvent for aromatics, and a solvent in textile dyeing.

Tri ethylene glycol also has mild disinfectant qualities and, when volatised, is used as an air disinfectant for virus and bacteria control.