What MEA Is
MEA stands for monoethanolamine, also written as 2-aminoethanol or ethanolamine. It is the simplest primary alkanolamine: one hydroxyl group and one primary amino group on a two-carbon chain. Its formula is C2H7NO, its molecular weight is 61.08, its CAS number is 141-43-5, and it is a clear, colourless, hygroscopic liquid with a boiling point of about 170.6 C, a melting point of about 10.3 C and a density of about 1.012 g/cm3 at 20 C. The molecule is a weak base and behaves as a viscous, water-miscible liquid that is corrosive in concentrated form, so the combination of amine chemistry and alcohol solubility is what makes it useful in so many industrial duties.
Typical Properties and Quality Parameters
| Parameter | Typical value |
|---|---|
| Chemical name | Monoethanolamine (2-aminoethanol) |
| Chemical formula | C2H7NO |
| CAS number | 141-43-5 |
| Molecular weight | 61.08 g/mol |
| Boiling point | Approximately 170.6 C at 101.3 kPa |
| Melting point | Approximately 10.3 C |
| Assay | 99.0 % min for standard industrial grade |
| Water content | Typically not more than 0.5 % |
| Colour | Reported as Pt-Co (APHA) units |
Certificates of analysis normally report assay by gas chromatography, water by Karl Fischer titration under ASTM E203, colour on the platinum-cobalt scale under ASTM D1209, and flash point by Pensky-Martens closed cup under ASTM D93 or ISO 2719.
Gas Treating: The Largest Single Use
Monoethanolamine is the classic absorbent for acid gas removal. In natural gas processing, refinery hydrogen units and ammonia plants, an aqueous MEA solution contacts the gas stream in an absorber and chemically binds carbon dioxide and hydrogen sulphide, which are then released in a regenerator by steam stripping. The lean solution is recirculated, so the amine acts as a recyclable reagent rather than being consumed. MEA gives a high acid gas pickup per unit of circulation, but it is more prone to degradation by carbonyl sulphide and carbon disulphide than sterically hindered or tertiary amines, which is why plant designers choose between MEA, DEA and MDEA according to the contaminant profile of the gas.
Frequently Asked Questions
Q: What does MEA stand for in the chemical industry?
A: Monoethanolamine. The same molecule is also called 2-aminoethanol or simply ethanolamine, and it should not be confused with methanol or with MDEA, which is a different amine used for selective hydrogen sulphide removal.
Q: What is MEA used for most?
A: Acid gas removal in gas processing and refining is the largest volume use. The remainder goes mainly to surfactant and detergent intermediates, textile auxiliaries, cement grinding aids, metalworking fluids and chemical synthesis.
Q: Why is MEA corrosive in storage but used in solutions?
A: The concentrated amine is strongly alkaline and attacks skin and eyes, while dilute aqueous solutions used in gas treating circuits are handled in closed, inhibited systems with carbon steel or stainless steel metallurgy selected for the service.
Q: How is MEA purity verified?
A: Assay is determined by gas chromatography, water by Karl Fischer titration under ASTM E203, colour under ASTM D1209, and flash point under ASTM D93 or ISO 2719. Both parties should agree on sampling and chromatographic conditions.
Q: What is the freezing behaviour of MEA?
A: Its melting point is about 10.3 C, so it can crystallise in unheated warehouses and outdoor tanks in winter. Heated storage, insulated lines and drum warmers prevent solidification and pumping problems.
Q: Is MEA the same as DEA or MDEA?
A: No. MEA is the primary amine with one ethanol group, DEA is the secondary amine with two, and MDEA is a tertiary methyl-diethanol amine. They differ in acid gas selectivity, degradation resistance and regeneration energy, so the choice is process specific.
