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N-Methyldiethanolamine MDEA

Synonyms: N-Methyldiethanolamine, MDEA, N-Methylaminodiglycol, N-Methyldiethanolamine, Methyl diethanolamine, N-methyl-diethanolamine, N-Methyldiethanolimine, N-Methyliminodiethanol, 2,2'-methyliminodiethanol, 2,2'-(Methylimino)diethanol, Methyldiethanolamine, Methylbis(2-hydroxyethyl)amine


N-Methyldiethanolamine (MDEA) is a tertiary amine commonly used to remove acid gases from gas streams. 


N-Methyldiethanolamine, also called MDEA or Methyldiethanolamine, is used in amine gas treating /gas sweetening /acid gas removal, the removal of hydrogen sulfide and carbon dioxide from gasses in the petrochemical industry.


N-Methyldiethanolamine (MDEA), a well-known and popular amine for gas treatment, has the formula CH3N(C2H4OH)2 and, like R2NH, is a type of secondary amine.


CAS Number: 105-59-9

EC Number: 203-312-7

N-Methyldiethanolamine (MDEA)


Mol. formula: C5H13NO2

Properties of N-Methyldiethanolamine (MDEA)


Chemical formula: C5H13NO2

Molar mass: 119.164 g·mol−1

Appearance: Colorless liquid

Odor: Ammoniacal

Density: 1.038 g mL−1

Melting point: −21.00 °C; −5.80 °F; 252.15 K

Boiling point: 247.1 °C; 476.7 °F; 520.2 K

Solubility in water: Miscible

Vapor pressure: 1 Pa (at 20 °C)

Refractive index (nD): 1.4694

Viscosity: 101 mPa s (at 20°C) 


Methyldiethanolamine (MDEA) is an active substance in fabric softeners and is a good alternative to TEA esterquats. 


In the paints industry, Methyldiethanolamine (MDEA) can be utilized in the cationic modification of acrylic polymer dispersions. 


N-Methyldiethanolamine (MDEA) is utilized in combination with perfluoroalkyl polymers in the production of silicone-based textile finishing agents. 


N-Methyldiethanolamine (MDEA) is employed as a precursor for certain active substances in the medical industry.


N-Methyldiethanolamine (MDEA) is a selective absorbent for H2S in the presence of CO2 and for the bulk removal of acid gases.


Methyldiethanolamine, also called MDEA, became important in the gas-treating market in recent years because MDEA, a tertiary amine, shows high selectivity for H2S over CO2 in gas streams containing both gases. 


N-Methyldiethanolamine solutions have the highest loading compared to any primary or secondary amine, which makes their circulation rate the lowest. 


N-Methyldiethanolamine has the lowest heat requirements for regeneration as it has the lowest heat of reaction with H2S and CO2. 


Besides this, it has the lowest specific heat solvent losses and a low freezing point (about − 32°C). 


N-Methyldiethanolamine is used in many unique solvent formulations, especially in combination with Piperazine, to enhance its reaction rate.


N-Methyldiethanolamine is a commonly used solvent for treating gases in order to remove H2S and CO2. 

The process is commonly known as the gas sweetening process, as the odor of the processed product is improved by the absence of hydrogen sulfide. 

The amine gas treating process is commonly employed in refineries, petrochemical plants, the food & beverage industry, and natural gas processing plants.

 Gas treating is a major application of N-Methyldiethanolamine. 


The oil & gas industry accounts for more than 50% demand for MDEA. 


Expansion of the gas treating segment across the globe is projected to increase the demand of MDEA across the globe




N-Methyldiethanolamine is used as a co-initiator for type II photoinitiator combinations. 


As a neutralizing agent, N-Methyldiethanolamine increases resin solubility and improves solution stability by reducing pH drift. 

Additionally, it aids pigment dispersion.



Foams and Elastomers


N-Methyldiethanolamine can be used as a chain extender during the synthesis of polyol-based polyurethane foams and elastomers.





N-Methyldiethanolamine is used as a co-initiator for type II photoinitiator combinations. 


As a neutralizing agent, N-Methyldiethanolamine increases resin solubility and improves solution stability by reducing pH drift. Additionally, it aids pigment dispersion.



Metal Working


In metal working fluids, N-Methyldiethanolamine is used both as a pH buffer as well as an anticorrosion additive.





N-Methyldiethanolamine forms quat salts with fatty acids which then find application in fabric softener formulations.




Preferred IUPAC name: 2,2′-(Methylazanediyl)di(ethan-1-ol)


Other names: Bis(2-hydroxyethyl)(methyl)amine















Substance names and other identifiers




2,2'-(methylimino)diethanol; N-methyldiethanolamine








Bis(2-hydroxyethyl) methyl amine


Ethanol, 2,2'-(methylimino)bis-


Ethanol, 2,2'-(methylimino)di-






















Translated names

2,2'-(metilimino)dietanolis N-metildietanolaminas (lt)


2,2'-metiliminodietanol N-metildietanolamin (sl)


2,2'-μεθυλιμινοδιαιθανόλη N-μεθυλοδιαιθανολαμίν (el)


2,2’-(metilimino)dietanol N-metildietanolamin (hu)





IUPAC names





















N,N(Bis-2 Hydroxy ethyl) Methylamine









Trade names



Amietol M12


Bis(2-hydroxyethyl) methyl amine




Ethanol, 2,2'-(methylimino)bis- (9CI)


Ethanol, 2,2'-(methylimino)di- (6CI, 8CI)



























Methyldiethanolamine, known as N-methyl diethanolamine and more commonly as MDEA, is an organic compound with the formula CH3N(C2H4OH)2. 


It is a colorless liquid with an ammonia odor. 


It is miscible with water, ethanol, and benzene. 


A tertiary amine, it is widely used as a sweetening agent in chemicals, oil refineries, syngas production, and natural gas.


Gas Sweetening

Maurice I. StewartJr. PhD, PE, in Surface Production Operations (Third Edition), Volume 2, 2014


MDEA Systems


MDEA is a tertiary amine, which, like the other amines, is used to sweeten natural gas streams. 


MDEA's major advantage over other amine processes is that it can be used to selectively remove H2S in the presence of CO2. 


If the gas is contacted at pressures ranging from 800 to 1000 psig (5500-6900 kPa), H2S levels can be reduced to concentrations required by pipelines. 

At the same time, 40-60% of the CO2 present flows through the contactor untreated.


CO2/H2S Ratio

In cases where a high CO2/H2S ratio is present, MDEA can improve the quality of the acid gas stream to a Claus recovery plant, but the higher CO2 content of the treated residue gas must be tolerated.


Solution Concentration and Solution Loading

Solution strengths typically range from 40% to 50% MDEA by weight. 

Acid gas loading varies from 0.2 to 0.4 or more moles of acid gas per mole of MDEA, depending on the supplier. 

Methyldiethanolamine has a molecular weight of 119. 

Methyldiethanolamine solution makeup is dependent upon the supplier. 

It can be adjusted to optimize treatment for a particular gas inlet composition.




Higher allowable MDEA concentration and acid gas loading reduce circulation flow rates. 

Significant capital savings are realized due to reduced pump and regeneration requirements. 

MDEA has a lower heat requirement due to its low heat of regeneration. 

In some applications, changing from DEA to MDEA can reduce energy requirements for gas treating by as much as 75%.




Similar compounds are monoethanolamine (MEA), a primary amine, and diethanolamine (DEA), a secondary amine, also used for treating amine gas. 


MDEA's defining characteristic, compared to these other amines, is its ability to preferentially remove H2S (and strip CO2) from sour gas streams.


MDEA's popularity as a solvent for gas treatment stems from several advantages it has over other alkanolamines. 


One of these advantages is low vapor pressure, which allows for high amine compositions without appreciable losses through the absorber and regenerator. 

MDEA is also resistant to thermal and chemical degradation and is largely immiscible with hydrocarbons. 


Methyldiethanolamine is a standard base note in perfumes to allow the fragrance to last. 


Lastly, methyldiethanolamine has a relatively low heat of reaction with hydrogen sulfide and carbon dioxide, allowing for lower reboiler duties and, thus, operating costs.



N-Methyldiethanolamine blends

MDEA is less reactive towards CO2 but has an equilibrium loading capacity approaching 1 mole CO2 per mole amine.

It also requires less energy to regenerate.

To combine the advantages of MDEA and the smaller amines, MDEA is usually mixed with a catalytic promoter such as piperazine PZ or a fast-reacting amine such as MEA to retain reactivity but lower regeneration costs. 


Activated MDEA or aMDEA uses piperazine as a catalyst to increase the speed of the reaction with CO2. 

It has been commercially successful.

Many tests have been done on the performance of MDEA/MEA or MDEA/piperazine mixtures compared to single amines. 

When experiments were performed in the University of Regina pilot plant modeled after a natural gas plant, CO2 production rates were higher than MEA for the same heat duty and total molar concentration. 


Insignificant trace amounts of degradation products were also detected.

However, when the same control variables and tests were conducted at the Boundary Dam Power Station plant, the mixed solvent's CO2 production rate was lower than MEA's.


This was a result of the reduction in the capacity of the solvent to absorb CO2 after degradation. 

Because the Boundary Dam plant is a coal-fired power plant, it operates under harsher environments and produces an impure flue gas containing fly ash, SO2, and NO2, fed into carbon capture. 


Even with flue gas pretreatment, there is still enough to produce degradation products such as straight-chain amines and sulfur compounds, which accumulate to the point that it is no longer possible to regenerate MEA and MDEA.


For these blends to successfully reduce heat duty, their chemical stabilities must be maintained.





The primary oxidative degradation products of MDEA include monoethanolamine (MEA), methyl-aminoethanol (MAE), diethanolamine (DEA), the amino acids bicine, glycine, and hydroxyethyl sarcosine (HES), formyl amides of MAE and DEA, ammonia, and the stable salts formate, glycolate, acetate, and oxalate.


In an industrial plan that utilizes Methyldiethanolamine, oxidative degradation will most likely shift to the cross exchanger, where temperatures exceed 70 °C. 

Higher temperatures and higher CO2 loading accelerate the degradation rate, increasing alkalinity loss and total formate production. 


While N-Methyldiethanolamine is more resistant to degradation as a standalone than MEA, Methyldiethanolamine is preferentially degraded in an MDEA/MEA blend.

Because the blend could potentially hurt atmospheric admissions because it forms DEA and MAE, which could form nitroso-compounds or diethylnitrosamine and diethylnitraine.


In the Boundary Dam plant, emissions increased when CO2 loading of lean amine increased for the blend and MEA.

However, decreasing the lean loading increases the reboiler heat duty, which results in an apparent tradeoff between emissions and heat duty or energy costs.


This compound should not be confused with the recreational drug methylenedioxyethylamphetamine, which is also abbreviated MDEA.


Methyldiethanolamine, also known as N-methyl diethanolamine and more commonly as MDEA, is the organic compound with the formula CH₃N(C₂H₄OH)₂. 

It is a colorless liquid with an ammonia odor. It is miscible with water, alcohol, and benzene. 

As a tertiary amine, it is widely used as a sweetening agent in chemical plants, oil refineries, syngas, and natural gas production. 

MDEA is less corrosive with lower energy requirements used in acid gas removal applications.


Production of N-Methyldiethanolamine

N-Methyldiethanolamine is produced by ethoxylation of methylamine using ethylene oxide:


CH3NH2 + 2 C2H4O → CH3N(C2H4OH)2

Another route involves hydroxymethylation of diethanolamine followed by hydrogenolysis.



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