Triethylene Glycol (TEG)
Three glycol units in a row, and the most water-hungry of the family. The standard medium for drying natural gas, and a low-volatility diol for resins and plasticisers.
Molecular Structure
What is Triethylene Glycol (TEG)?
Triethylene glycol is the third member of the ethylene glycol series — three two-carbon units joined by two ether oxygens, with hydroxyls at each end. It is more viscous and far less volatile than MEG, boiling at 285 °C.
Four oxygen atoms in one chain give TEG an exceptional affinity for water. It hydrogen-bonds to water strongly enough to strip it out of a gas stream, and its very low vapour pressure means it does not evaporate away in the process. That combination is what makes it the industry-standard gas dehydration medium.
The economics rest on regeneration. Wet TEG leaving a contactor tower is heated in a reboiler to around 200 °C, driving off the absorbed water, and the lean glycol is recirculated. TEG's thermal stability limit — roughly 204 °C, above which it degrades — sets the practical ceiling on how dry the regenerated glycol can be.
Chelora supplies TEG at ≥99.0 wt% with water, DEG, tetraethylene glycol, acidity, chloride and iron certified. Dehydration-service buyers should note that chloride and iron drive corrosion and foaming in contactor systems, and we specify both tightly.
Quick Reference
Key Physical & Chemical Properties
Structure & Bonding
Three glycol units, two ether oxygens, two terminal hydroxyls — four oxygen atoms in all, each of them a hydrogen-bond acceptor. That is the entire reason TEG pulls water out of natural gas better than its shorter relatives.
Skeletal structure — three glycol units, two ether linkages
Structural Identity
- IUPAC Name2,2'-(Ethylenedioxy)diethanol
- Common namesTEG, triglycol
- Molecular FormulaC₆H₁₄O₄
- Molecular Weight150.17 g/mol
- StructureThree glycol units + two ether oxygens
- Hydrogen-bond acceptorsFour oxygen atoms
- Thermal stability limit≈ 204 °C in service
- Vapour pressureVery low — minimal carryover loss
- HygroscopicStrongly — the most of the series
- CAS Number112-27-6
- InChI KeyZIBGPFATKBEMQZ-UHFFFAOYSA-N
Product Specifications
Chelora supplies Triethylene Glycol (TEG) in standard and custom grades. Contact us for specification sheets tailored to your process.
| Chemical name | Triethylene glycol |
|---|---|
| CAS Number | 112-27-6 |
| Molecular formula | C₆H₁₄O₄ |
| Molecular weight | 150.17 g/mol |
| Purity (min) | ≥ 99.00 wt% |
| Diethylene glycol (max) | ≤ 0.50 wt% |
| Tetraethylene glycol (max) | ≤ 0.50 wt% |
| Water (max) | ≤ 0.10 wt% (Karl Fischer) |
| Acidity as acetic acid (max) | ≤ 0.005 wt% |
| Chloride (max) | ≤ 1.0 ppm wt |
| Iron (max) | ≤ 0.20 ppm wt |
| Ash (max) | ≤ 50 ppm wt |
| Colour | ≤ 10 Pt-Co (Hazen) |
| Specific gravity | 1.1230 – 1.1270 at 20/20 °C |
| Distillation range | 282 – 291 °C |
| Flash point | 177 °C (closed cup) |
| Autoignition temperature | 371 °C |
| Transport classification | Not regulated as dangerous goods |
Downstream Applications & Derivatives
Key derivative chains and industrial uses of Triethylene Glycol (TEG).
Natural Gas Dehydration
The dominant use. Lean TEG contacts wet gas in an absorber tower, strips out water to meet pipeline dew-point specification, and is regenerated by heating in a reboiler and recirculated.
Unsaturated Polyester & Polyols
A long, flexible diol used where a softer, tougher resin backbone is wanted — in UPR, polyester polyols and polyurethane systems.
Plasticiser Esters
Esterified with benzoic and fatty acids to give low-volatility plasticisers for PVC, adhesives, sealants and rubber compounds.
Air Treatment & Humidity Control
Used as a liquid desiccant in dehumidification systems, and historically as an air-disinfecting vapour in enclosed spaces.
High-Boiling Solvent
A water-miscible solvent with very low volatility, used in printing inks, cleaning formulations, and as a reaction medium where a high boiling point is required.
Heat Transfer & Technical
Secondary-loop heat transfer fluid formulations, brake fluid components, and a humectant and conditioning agent in textiles and paper.
Why source Triethylene Glycol (TEG) through Chelora Petrochem?
Verified Origin
Full origin certification and asset-backed supply chain documentation — no grey-market supply.
Grade Flexibility
Dehydration and industrial grades supplied. Chloride, iron and acidity specified tightly for contactor service, where they drive corrosion, foaming and glycol degradation.
Full Documentation
CoA, SDS, UN transport docs, REACH compliance, and destination-market certificates with every shipment.
Logistics Support
Experienced in bulk aromatic liquid logistics — ISO tanks, road tankers, and drums with nitrogen blanketing where required, for Indian and international delivery.
Storage & Handling Guidelines
Always refer to the full SDS before handling. The following is a summary of key requirements.
- Store in stainless steel, aluminium or lined tanks under a nitrogen pad — glycols are hygroscopic and pick up water from humid air, which is a specification failure rather than a safety issue.
- Keep carbon steel out of the wetted path where colour and iron specifications matter; iron pickup shows up directly as colour on the certificate.
- Protect from prolonged heat and air. Extended exposure to both causes oxidation to aldehydes and organic acids, which raises acidity and destroys UV transmittance.
- Segregate grades rigorously. Fibre-grade, industrial and pharmacopoeial materials must not share hoses, pumps or lines, and dedicated equipment is the norm.
- Verify identity on receipt, not just on paper. Glycols look alike, mix freely and are commonly mis-shipped or adulterated — confirm by test before the material enters your process.
- Bund all storage and prevent any release to drains, surface water or groundwater.
- Provide eyewash and washing facilities at transfer points, and control mist or aerosol generation at spray and heated-handling points.
- Label every container clearly and never decant into unmarked or food-type containers.
- In dehydration service, keep reboiler temperature below about 204 °C — above that TEG degrades thermally, and the acidic degradation products then attack the system.
Hazard Summary
Classification: TEG has no harmonised CLP classification and is generally not classified as hazardous. It has low acute oral toxicity and is not a skin or eye corrosive. Check the SDS for the specific grade rather than assuming.
Relative to MEG and DEG: TEG is markedly less toxic than the shorter glycols. That said, it should still never be substituted into food, pharmaceutical or oral-care applications, and it must not be treated as interchangeable with propylene glycol or glycerine.
Thermal degradation: The realistic in-service hazard is heat. Above roughly 204 °C, TEG decomposes to acidic and aldehydic products that corrode carbon steel, foul the reboiler and cause foaming in the contactor. Reboiler temperature control is the primary safeguard.
Fire: A combustible liquid with a flash point of 177 °C. In gas dehydration it is routinely handled well above ambient temperature, so heated-service fire risk assessment is warranted even though it is not a flammable liquid at ambient.
Exposure limits: No widely established occupational exposure limit. Control mist and heated vapour generation with general good practice.
PPE minimum: Safety glasses, nitrile gloves, and heat-resistant protection where hot glycol is sampled or drained; hot TEG causes thermal burns.
Consult the full SDS for exposure limits, spill containment, emergency response, and disposal before any use.
Frequently Asked Questions
Technical and commercial questions about Triethylene Glycol (TEG) sourcing and specifications.
What is TEG used for?
Natural gas dehydration dominates. TEG absorbs water from gas in a contactor tower to bring it down to pipeline dew-point specification, then gives that water up when heated in a regenerator and is recirculated. Beyond that it is a diol for unsaturated polyester and polyurethane polyols, a feedstock for low-volatility plasticiser esters, a liquid desiccant in air dehumidification, and a high-boiling water-miscible solvent.
Why is TEG used for gas dehydration rather than MEG?
Two reasons. TEG has four oxygen atoms available for hydrogen bonding against MEG's two, so it holds water more strongly and achieves lower dew points. And its vapour pressure is far lower, so much less glycol is lost by evaporation into the dry gas leaving the tower. MEG is used in gas service too, but for a different job — injected into subsea lines to inhibit hydrate formation rather than to dry the gas.
Why does reboiler temperature matter so much in TEG systems?
Because regeneration works by boiling water out of the glycol, and the hotter you run, the drier the lean glycol and the better the dew point achieved. But TEG starts to degrade thermally at around 204 °C, producing acidic and aldehydic breakdown products that corrode the system, foul the reboiler and cause the contactor to foam. Operators therefore run as hot as they can without crossing that line, often using stripping gas to get drier glycol instead of more heat.
What impurities matter in dehydration-grade TEG?
Chloride and iron above all. Chloride drives pitting corrosion in the carbon steel of contactors and reboilers, and iron indicates corrosion is already occurring and catalyses further glycol degradation. Acidity is monitored as a direct measure of degradation. Water content on delivery matters less, since the system removes water continuously, but high DEG or tetraethylene glycol content shifts the boiling behaviour and regeneration performance.
How does TEG differ from MEG and DEG?
It is the third member of the same series. Each added ethylene oxide unit brings another ether oxygen, raising boiling point, viscosity and water affinity while lowering volatility and hydroxyl density per unit mass. MEG at 197 °C is the polyester monomer; DEG at 246 °C softens resins and dissolves things; TEG at 285 °C is hygroscopic and non-volatile enough to dry gas. TEG is also the least toxic of the three.
What documentation does Chelora provide?
Every shipment includes a Certificate of Analysis covering purity, DEG and tetraethylene glycol content, water, acidity, chloride, iron, ash, colour, specific gravity and distillation range; a Safety Data Sheet (GHS/REACH); confirmation that the material is not regulated as dangerous goods for transport; an origin certificate; and any destination-market certificates required.
Request a quote or specification sheet
Talk to Chelora's sourcing team about Triethylene Glycol (TEG) grade, volume, logistics, documentation, and lead times. We respond within one business day.
