Monoethanolamine (MEA) 99% for Gas Treating & Surfactant Formulations

Monoethanolamine (MEA) 99% for Gas Treating & Surfactant Formulations is the high-purity alkanolamine identified by CAS 141-43-5 and EINECS 205-483-3. At 99 wt% minimum assay, the residual water content is controlled because water entering closed-loop acid-gas absorption shifts the amine mass balance and, in alkanolamide reactors, retards the condensation rate. The material freezes at 10.3 °C, boils at 170.9 °C at 101.325 kPa, and has a density of 1.016 g/cm³ at 20 °C. A typical industrial specification sets assay ≥99.0 wt%, water ≤0.3 wt%, color ≤15 Pt-Co, and trace chloride below 5 mg/kg for corrosion-sensitive amine-loop service. The molecule contains a primary amine and a primary alcohol, so the same lot can form carbamate salts with acid gases and undergo amidification or neutralization in surfactant manufacturing.

Property	Typical specification or value	Test method
MEA assay	≥99.0 wt%	Acid-base titration, 0.5 mol/L HCl
Water	≤0.3 wt%	ASTM E203
Color	≤15 Pt-Co	ASTM D1209
Density at 20 °C	1.016–1.019 g/cm³	ASTM D4052
Freezing point	10.3 °C	Vendor differential scanning calorimetry, 10 K/min

Because the primary amine function is basic and the alcohol function is nucleophilic, the same grade can be moved from acid-gas removal service to fatty acid condensation without changing storage. However, transfer lines must be nitrogen-blanketed and maintained above 15 °C to prevent crystallization in low ambient conditions. Storage in carbon steel is acceptable only for dry, CO₂-free material; for long-term service, 304 stainless steel or lined carbon steel is used to avoid iron contamination and color development. Suppliers commonly specify iron ≤0.5 mg/kg for material destined to personal-care amides.

Gas-Treating Loops, Lean/Rich Loading Windows, and Reboiler Limits

In packed absorption columns fed by 2–4 barg natural gas or refinery off-gas, MEA 99% is diluted with demineralized water to 15–20 wt%. The absorption reaction is stoichiometrically limited to 0.5 mol CO₂/mol MEA because two amines are required per CO₂ molecule, forming a carbamate and a protonated amine. The lean solvent enters the absorber at 35–50 °C, while the regenerator reboiler operates at 116–126 °C. The lean-rich plate-frame exchanger recovers heat from the 115 °C lean stream to preheat the rich solvent to 90–100 °C, reducing reboiler energy demand. Reboiler steam consumption is normally 3.5–4.2 MJ/kg CO₂ for conventional MEA regeneration, although actual duty depends on tower pressure, packing performance, and acid-gas composition. Common reported degradation products from MEA-CO₂ systems include 2-oxazolidinone and N-(2-hydroxyethyl)ethylenediamine; their accumulation consumes free amine and can increase solution viscosity.

Parameter	Typical window	Limiting mechanism
Lean solvent MEA concentration	15–20 wt%	Foaming and corrosion at higher concentration
Rich CO₂ loading	0.40–0.45 mol/mol	Viscosity rise and carbon steel corrosion
Lean CO₂ loading	0.10–0.15 mol/mol	Reboiler steam demand
Regenerator reboiler temperature	116–126 °C	MEA carbamate thermal degradation
Reclaimer kettle temperature	149–155 °C under vacuum	Free MEA recovery versus degradation

Plant operators measure amine strength and CO₂ loading by titration every shift; no single ISO method covers all gas-treating loop matrices. Rich loading above 0.45 mol/mol has been observed on production units to increase rich-solvent viscosity enough to reduce absorber mass-transfer efficiency and to raise differential pressure across structured packing, especially when high-aromatic refinery off-gas introduces foaming precursors. If lean loading cannot be driven below 0.10 mol/mol without exceeding 126 °C in the reboiler, the resulting thermal degradation can produce heat-stable salts that consume free amine and require more aggressive reclamation. Published data for this specific configuration is limited; these limits are licensor and vendor starting points, not universal design rules.

Hot amine loops constructed from carbon steel are limited to temperatures below approximately 80 °C for CO₂-loaded streams; above that range, general and localized corrosion accelerate, particularly in the regenerator tower, reboiler tube bundle, and lean-rich exchanger. For the high-temperature circuit, 304L or 316L stainless steel is used, and the reboiler tubes are often 316L or a more resistant alloy when chloride ingress is likely. Makeup water is controlled to chloride ≤5 mg/L and total dissolved solids ≤10 mg/L because chloride-induced pitting in hot welds has been observed in amine-loop service. Wet acid-gas systems fall within sour service, and pressure-boundary material selection is screened against NACE MR0175/ISO 15156.

Foaming events in the absorber can be triggered by hydrocarbons, water-soluble organic acid salts, iron sulfide, and degraded amine products. A conventional production-scale countermeasure is a slipstream of 2–5 vol% of circulating solvent through activated carbon beds and 10 µm filter cartridges; carbon filtration removes surface-active degradation compounds while the filters reduce particulate iron sulfide. The reclaimer kettle is operated at 149–155 °C under vacuum and recovers free MEA while rejecting heat-stable salts. Operational boundaries include chloride>100 mg/kg in the circulating solvent and acid-gas loading>0.45 mol/mol, both of which shift the unit toward corrosion and foaming failure modes.

What Surface-Active Products Are Formulated from MEA 99%?

MEA-based alkanolamides are used as foam stabilizers, viscosity builders, and emulsifiers in liquid detergents, hard-surface cleaners, and personal cleaning formulations. The main products include lauric monoethanolamide, cocamide MEA, and stearamide MEA. In contrast to simple neutralization, amidification requires removal of water of reaction at 150–160 °C under nitrogen or vacuum. The acid value is used to track conversion, with lauric acid loads starting at acid values of 275–285 mg KOH/g and ending at ≤5 mg KOH/g according to ASTM D1980. Free MEA content is typically controlled to 0.1–1.0 wt% to balance foam stabilization and skin irritation potential. Reactors are stainless steel or glass-lined agitated vessels with pitched-blade turbine impellers and condenser systems; nitrogen sparge removes evolved water and protects color.

MEA 99% also neutralizes dodecylbenzene sulfonic acid and other anionic sulfonic acid or phosphate ester intermediates. The exothermic neutralization is controlled below 60 °C to limit color bodies; the resulting amine salt raises electrolyte concentration in aqueous surfactant systems and can shift the viscosity curve of shampoo or hand-dish formulas into shear-thinning gel behavior. In aqueous personal-care thickeners, MEA neutralizes carbomer polymers to pH 6.5–7.5, producing transparent gels with viscosity values measured by Brookfield viscometer at 20 rpm and 25 °C. The neutralization is stoichiometric, requiring approximately 0.4–0.6 wt% MEA for a 0.25 wt% carbomer network, depending on acrylic acid residue content and desired rheology. Because MEA is hygroscopic, drums and totes should be blanketed with nitrogen and kept above 15 °C. Production kettles with external cooling and anchor agitators are preferred to avoid local high pH and gel grain formation.

In lauric acid monoethanolamide production, the fatty acid feed is charged with MEA at a molar ratio of 1.00–1.10 MEA:fatty acid to compensate for distillative amine loss. The reactor is heated to 150–160 °C under a nitrogen sweep rate of 0.2–0.3 Nm³/h per tonne, or under vacuum at 30–50 kPa absolute, to remove the water of reaction. The reaction is equilibrium-limited; water removal shifts the amidation toward completion. Acid value is monitored until it falls below 5 mg KOH/g by ASTM D1980, and residual water is confirmed below 0.2 wt% by ASTM E203. Prolonged heating above 170 °C has been associated with colored impurities and side reactions, although published kinetic data for all fatty-chain distributions is limited.

MEA 99% also enters downstream ethylenediamine and chelant synthesis. For such operations, the feed is maintained under dry nitrogen with oxygen ≤0.1 vol% to prevent oxidative color and impurity formation, and transfer equipment is constructed of 304 or 316 stainless steel. Incompatibilities include copper, brass, and galvanized surfaces, which are attacked by MEA and generate colored metal-amine complexes. Strong oxidizers and uncontrolled contact with concentrated mineral acids must also be excluded because the heat of neutralization can exceed 100 °C in low-mass applications.