Triethylene Glycol Grades at a Glance
Triethylene glycol (TEG, CAS 112-27-6) is a colourless, hygroscopic, low-volatility diol of the ethylene glycol family. It is produced mainly as a co-product of ethylene oxide-based glycol manufacture and is supplied commercially in several purity grades. Choosing the right grade matters because water content, residual diethylene glycol (DEG) and acidity limits determine performance in gas dehydration, coatings, plasticisers and pharmaceutical applications.
| Grade | Purity | Key Specifications | Primary Use |
|---|---|---|---|
| Industrial grade | ≥99.0% | Water ≤0.2%, DEG ≤0.3%, low acidity | Natural gas dehydration, general solvents |
| High-purity grade | ≥99.5% | Ultra-low water, metals and trace impurities | Pharmaceuticals, cosmetics, specialty chemicals |
| Technical grade | ≈98% | Higher water and DEG tolerance | Humectants, non-critical applications |
| Reagent / lab grade | ≥99.9% | Tight impurity limits, certified for analysis | Research, analytical standards |
How to Choose the Right TEG Grade
For natural gas dehydration, industrial-grade TEG is the standard choice: its water specification is tight enough to maintain regeneration efficiency in glycol contactors, and its acidity limit protects downstream equipment. High-purity grade is preferred where trace metals and residual glycols must be minimised, for example in pharmaceutical intermediates, cosmetics and specialty resin systems. Technical grade offers a cost-effective option for humectant and process applications where wider tolerances are acceptable, while reagent grade is reserved for laboratory and analytical work that demands a certified impurity profile.
Key Properties of Triethylene Glycol
TEG has the molecular formula C6H14O4 and a molecular weight of 150.17 g/mol. It boils at 285–295 °C, melts at about −7 °C and has a closed-cup flash point of approximately 177 °C. Its density is about 1.124 g/cm³ at 20 °C. TEG is fully miscible with water and most polar organic solvents and is strongly hygroscopic, which is the basis of its use as a desiccant in natural gas dehydration.
Safety and Handling
TEG has low acute oral, dermal and inhalation toxicity and is not classified as a carcinogen by IARC. When handled correctly it is regarded as one of the safer industrial glycols. Nevertheless, standard precautions apply: wear chemical-resistant gloves and safety goggles, ensure adequate ventilation in areas of heavy use, avoid ingestion and eye contact, and clean up spills promptly. Store TEG in a cool, dry, well-ventilated area in tightly closed containers, away from strong oxidising agents.
How to Buy TEG: Specifications, Documentation and Logistics
When sourcing TEG, specify the grade, the purity you require and the packaging format. Common options are 200–230 kg drums, 1,000 L IBC totes and ISO tank or flexitank containers for bulk volumes. Request a batch Certificate of Analysis (COA) covering purity by gas chromatography, water content by Karl Fischer titration, acidity and colour (APHA), together with the Safety Data Sheet (SDS). Suppliers operating quality systems certified to ISO 9001:2015 and environmental management to ISO 14001:2015 provide the most consistent documentation for international trade.
Frequently Asked Questions
What is the CAS number of triethylene glycol? TEG is registered under CAS 112-27-6, with EINECS/EC number 204-011-6 and the molecular formula C6H14O4.
Which TEG grade is best for natural gas dehydration? Industrial grade at ≥99.0% purity is the standard for glycol dehydration units because its water and acidity limits support efficient regeneration and protect tower internals.
Is triethylene glycol the same as ethylene glycol? No. Ethylene glycol (CAS 107-21-1) is the base diol; triethylene glycol is a higher oligomer containing three oxyethylene units. TEG has a higher molecular weight, a much higher boiling point and far lower volatility, which is why it is preferred for gas dehydration and high-temperature applications.
Is TEG safe for food-contact or cosmetic use? Only grades that are expressly cleared under the applicable food-contact or cosmetic regulations of the destination market should be used. Verify regional compliance requirements with your supplier before use.
What packaging is available for bulk TEG? Typical formats are 200–230 kg drums, 1,000 L IBC totes and ISO tank or flexitank for large orders. Packaging can be customised to your destination and handling requirements.
How is TEG quality verified? Each batch is released with a COA that reports purity by gas chromatography, water by Karl Fischer titration, acidity, colour (APHA) and other agreed parameters.