Physical properties
1.Appearance and state: At normal temperature and pressure, it is a colorless or slightly yellow viscous liquid with a slight ammonia odor.
2.Hygroscopicity: It has strong hygroscopic properties, capable of absorbing moisture and carbon dioxide from the air.
3.Boiling point: relatively high, about 170°C. This is due to the presence of strong hydrogen bonds between molecules.
4.Melting point: approximately 10.5°C, so it may solidify in colder environments.
5.Density: Slightly greater than that of water.
6.Solubility:With water: infinitely miscible. This is one of its most important physical properties.With organic solvents: soluble in ethanol, acetone, glycerol, and various other organic solvents, but slightly soluble in ether, benzene, and n- heptane.
7.Viscosity: Has a certain viscosity and feels 'oily'.
Chemical properties
The amino group in the MEA molecule gives it basicity, allowing it to react with acids to form salts.
Its aqueous solution is more alkaline than ammonia water, but weaker than sodium hydroxide. It is a type of weak base.
Reaction example: HOCH₂CH₂NH₂ + HCl → HOCH₂CH₂NH₃⁺Cl⁻
This is the most important industrial application basis of MEA. It can undergo reversible reactions with acidic gases such as carbon dioxide (CO₂) and hydrogen sulfide (H₂S).
Reacts with CO₂: forming an unstable carbamate, a reaction that can be reversed upon heating, thereby releasing high-purity CO₂ and regenerating MEA.2 HOCH₂CH₂NH₂ + CO₂ + H₂O ⇌ (HOCH₂CH₂NH₃)₂CO₃
This feature makes it the preferred solvent for removing CO₂ and H₂S from natural gas, refinery gas, and synthesis gas (commonly known as 'decarbonization' or 'desulfurization').
Can react with epoxides such as ethylene oxide to produce larger molecules of ethanolamine derivatives.
Its amino group can react with acids, acid anhydrides, acyl chlorides, etc., to form amides.
Especially in environments with high temperatures, high concentrations, and high levels of acidic gases, MEA solutions are highly corrosive to metals such as carbon steel. In industrial applications, it is usually necessary to add corrosion inhibitors or use stainless steel equipment.
Main applications (based on its characteristics)
Gas purification: the largest use. It is used for desulfurization of natural gas, decarbonization of synthetic ammonia feed gas, and capture of CO₂ from flue gas, etc.
Surfactants: Used as intermediates for the production of emulsifiers, detergents, textile auxiliaries, and others.
Pharmaceuticals and pesticides: used as intermediates for synthesizing various drugs (such as sedatives and antihistamines) and pesticides.
Cement grinding aid: As one of the raw materials, it improves the grinding efficiency of cement.
Cosmetics: Used to produce fatty acid amides in personal care products, serving as thickeners and foam stabilizers.
Metalworking: added to cutting fluids and rust-preventive liquids as a corrosion inhibitor.
Safety and Storage (Important Notes)
Toxicity: It has a certain level of toxicity and is highly irritating and corrosive to the eyes, skin, and respiratory tract. Inhalation of its vapors or mist can damage the respiratory system, and contact with the liquid can cause severe eye and skin burns.
Flammability: Flammable liquid with a flash point of approximately 93°C, classified as a combustible material and should be kept away from fire sources.
Storage:Must be stored in a sealed container, as it will absorb CO₂ and moisture from the air.The container material should preferably be stainless steel, glass, or polyethylene plastic. Avoid using copper, aluminum, and their alloys, as MEA will react with them.Store in a cool, ventilated, and dry place.
Summary Table
| Chemical formula | HOCH₂CH₂NH₂ 或 MEA |
| Appearance | Colorless viscous liquid with an ammonia odor |
| Solubility | Infinitely miscible with water, soluble in alcohol, slightly soluble in ether |
| Chemical properties | Weakly alkaline, can reversibly react with acidic gases (CO₂/H₂S), hygroscopic |
| Core Application | Gas purification (desulfurization and decarbonization), surfactants, pharmaceutical and pesticide intermediates |
| Safety | Corrosive, irritating, flammable, toxic |
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