Natural-gas sweetening
Process Role: Selective H₂S and/or CO₂ removal Critical Procurement / Engineering Parameters: Purity, solvent strength, process selectivity
TECHNICAL PROCUREMENT INTELLIGENCE
Methyldiethanolamine (MDEA)
High-Purity Tertiary Amine Supply for Selective H₂S Removal and Acid-Gas Treatment
Methyldiethanolamine (MDEA) is a tertiary alkanolamine widely used in gas sweetening, particularly where selective H₂S removal or lower regeneration energy is desired. MDEA reacts rapidly with H₂S but absorbs CO₂ more slowly through bicarbonate chemistry unless promoted, giving process engineers flexibility in acid-gas selectivity.
For GCC and MENA buyers, technical suitability should be confirmed before shipment. OGSCM can coordinate specification review, manufacturer documentation, packaging format, batch traceability, dangerous-goods requirements where applicable, cross-border logistics and receiving-site constraints. Product claims such as food grade, pharmaceutical grade, oilfield grade, REACH/FCC/USP compliance or OEM approval should only be used when documented for the actual offered grade.
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Chemistry, Manufacturing Route & Material Behaviour
Unlike primary amines, MDEA has no N–H bond and does not form a stable carbamate directly with CO₂. CO₂ absorption therefore proceeds mainly through slower base-catalysed bicarbonate formation, while H₂S proton-transfer chemistry is fast. This kinetic difference enables selective H₂S removal in appropriate absorber designs. “Activated” or promoted MDEA uses additives such as piperazine to accelerate CO₂ absorption when deeper CO₂ removal is required.
Process-Engineering & Grade-Selection Considerations
- Do not assume one universal working concentration. Commercial gas-treating systems may operate at different wt% MDEA depending on acid-gas load, selectivity target, corrosion control and process licensor design.
- Monitor heat-stable salts, degradation products, dissolved metals, solids and hydrocarbons; solvent contamination can cause corrosion, foaming and capacity loss.
- MDEA generally has lower regeneration duty and lower vapour losses than MEA, but process performance is system-specific.
- Avoid copper and copper alloys in MDEA service; supplier guidance notes potential complex formation and compatibility issues. Carbon steel is commonly used in appropriate dry/clean service.
- For make-up chemical, control purity, water and colour; for reclaimed/used solvent, much broader analysis is required.
◎ Technical Specifications
| Property | Value |
|---|---|
| Formula | C₅H₁₃NO₂ |
| CAS | 105-59-9 |
| Molar mass | 119.16 g/mol |
| Amine type | Tertiary alkanolamine |
| Boiling point | ≈243–247°C, source dependent |
| Freezing point | ≈−21°C |
| Density | ≈1.04 g/cm³ at 20°C |
| Water solubility | Completely miscible / highly soluble |
| Vapour pressure | Very low at ambient temperature |
| Primary use | Acid-gas removal; selective H₂S service and promoted MDEA processes |
Values shown are reference/typical values, not a sales specification. Final acceptance must be based on the offered manufacturer grade, test method, COA and buyer specification.
Applications
Refinery amine units
Process Role: Acid-gas removal from fuel/process gas Critical Procurement / Engineering Parameters: H₂S/CO₂ loading, contaminants, corrosion
Tail-gas treating
Process Role: Selective H₂S capture in suitable schemes Critical Procurement / Engineering Parameters: Selectivity and absorber kinetics
Promoted MDEA
Process Role: Deep CO₂ removal with activator Critical Procurement / Engineering Parameters: Promoter identity/concentration and licensor design
Chemical formulations
Process Role: pH/catalyst/intermediate uses Critical Procurement / Engineering Parameters: Industrial grade and impurity requirements
Storage, Handling, Materials Compatibility & HSE
Store in clean, closed, compatible tanks protected from contamination and excessive heat. MDEA is hygroscopic. Use appropriate ventilation and avoid copper/copper-alloy wetted components. Follow supplier SDS for PPE and spill control. For gas plants, keep fresh make-up chemical segregated from degraded/reclaimed solvent streams to preserve quality traceability.
HSE control principle
Use the current product-specific SDS, local dangerous-goods requirements, receiving-site risk assessment and applicable engineering standards. Website text should never substitute for a supplier SDS or site procedure.
HSE control principle
Use the current product-specific SDS, local dangerous-goods requirements, receiving-site risk assessment and applicable engineering standards. Website text should never substitute for a supplier SDS or site procedure.
RFQ Specification Checklist
- Gas-treating high-purity grade or general industrial grade
- Minimum MDEA assay and maximum water
- Colour requirement
- Required related-amine/impurity limits
- Drums, IBC or bulk supply
- Annual make-up consumption and turnaround charging requirement
- COA/SDS, origin and compatibility/handling documentation
Quality Control, COA Parameters & Test Methods
MDEA performance in the intended process. Typical COA requirements include MDEA assay, water content, colour, density, amine value, related amines, metals, and heat-stable salts, measured using suitable methods such as GC, titration, Karl Fischer analysis, APHA/Pt-Co colour measurement, ASTM D4052, ICP, ion chromatography, or supplier methods.
These parameters are used to verify primary purity, solution strength, product grade, functional concentration, blending consistency, process impurity control, corrosion risk, and solvent condition monitoring. Heat-stable salts are typically evaluated in circulating solvent systems rather than as a routine fresh-product COA parameter.
Final testing requirements should be aligned with the producer specification, customer requirements, and intended application.
Why Choose OGSCM?
Application-Driven Solutions
We match the right grade to your process needs.
Reliable Supply Chain
On-time delivery with strong regional & global logistics.
Quality You Can Trust
Strict quality control and batch consistency.
Expert Support
Technical & commercial support throughout your procurement journey.
Regional Presence
Serving industries across GCC and MENA with local expertise.
Frequently Asked Questions
H₂S acid-base transfer is fast, while CO₂ absorption by unpromoted MDEA is kinetically slower. Absorber design can exploit this difference.
No. MDEA usually offers lower regeneration duty and better selectivity, while MEA has faster CO₂ kinetics. Selection depends on treated-gas specification and process design.
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