Germany Just Cleared the CO2 Offramp. The Solvent Waiting on It Was Patented in 1930.

Carbon capture has spent a decade being described as a technology problem. It was never mainly a technology problem. The absorber chemistry has been commercial since the Hoover administration. What has been missing is somewhere to put the carbon dioxide once you have gone to the trouble of catching it — and at the end of August, one of those places got its final regulatory clearance.

What actually happened in Bremen

The industrial gas maker Messer is forming a joint venture with the energy and logistics firm Ambrian Energy to build a carbon dioxide export terminal in Bremen, Germany. The venture, called CarbonBridge, cleared antitrust review by European regulators at the end of August 2026. Captured CO₂ will arrive by railcar from a range of heavy-industry customers, chemical makers among them, and ship out to geological storage sites beneath the North Sea. Capacity is 2.3 million metric tons a year at opening, with expansion to roughly 4 million contemplated. Longer term, the venture hopes to add pipeline connections and to supply plants that convert CO₂ into chemicals and fuels.

The detail in that same report worth more than the terminal itself: Messer says it already operates more than 300 capture plants using aqueous amine systems worldwide. Not planned. Not piloted. Operating.

The solvent waiting on that terminal was patented in 1930

Amine scrubbing is not a climate-era invention. Robert Roger Bottoms of Louisville, Kentucky filed US 1,783,901, “Process for separating acidic gases,” on 7 October 1930; it was granted on 2 December 1930 and assigned to The Girdler Corporation. Triethanolamine came first commercially, and monoethanolamine and its relatives displaced it in gas-treating plants over the following decades. The absorber-and-stripper arrangement Bottoms described — contact the gas with a lean amine solution, heat the rich solution to drive the acid gas back off, return the regenerated amine — is recognisably the same loop running today.

If Bremen opens on the early end of its schedule, the offramp for the carbon dioxide arrives the same year Bottoms’ patent turns one hundred.

How MEA actually holds on to CO₂

Monoethanolamine (CAS 141-43-5, C₂H₇NO, MW 61.08) is a primary amine with an alcohol on the other end. In aqueous solution its nitrogen attacks dissolved CO₂ to form a carbamate. That reaction releases a proton, and the proton has to go somewhere — in a primary-amine system a second amine molecule accepts it. Two amines are consumed per molecule of CO₂ captured.

That is the whole reason for the ceiling everyone quotes. The theoretical maximum loading of a primary or secondary amine is 0.5 mol CO₂ per mol amine, and it is stoichiometric, not an engineering shortfall you can design your way past. Tertiary amines such as MDEA and hindered amines dodge it by routing through bicarbonate instead of carbamate, which lifts the loading ceiling but slows the kinetics.

Why the solvent is a consumable, not an asset

This is the part that gets left out of the summary slide. Amine in a capture plant is not a one-time fill that circulates forever. It degrades by two independent routes, and you buy replacement volume continuously.

Oxidative degradation

The National Petroleum Council’s CCUS roadmap is unusually candid about this: “Amine oxidation is a unique problem in the application of amine scrubbing to CO₂ capture from oxygen-containing flue gas. Even with numerous detailed investigations over the last 15 years, there is not yet a clear understanding of the mechanisms by which it takes place.”

What is established is which metals accelerate it. The same document reports that Fe²⁺ and Mn²⁺ — arriving from corrosion or leaching of fly ash — and Cu²⁺, which is deliberately added as a corrosion inhibitor, are all potent catalysts of MEA oxidation. The additive dosed to protect the steel helps destroy the solvent. Oxidation rates across candidate amines vary by a factor of about twenty; piperazine and tertiary amines such as MDEA resist it, and hindered amines like AMP are especially resistant.

Thermal degradation

Heat is the other route, and it sets the stripper ceiling. MEA’s T_max — the temperature at which the loaded solvent degrades at 2% per week — is about 120 °C. Run the stripper hotter to get CO₂ off at higher pressure and save on compression, and you pay in amine.

The number to argue about: make-up rate

Here is where two authoritative sources sit in productive tension.

On the economics, the NPC roadmap sets the tolerance plainly: “MEA losses equivalent to $1 to $2/tonne CO₂ are acceptable with an amine price of $2/kg.” At that price, acceptable loss works out to roughly 0.5 to 1.0 kg of MEA per tonne of CO₂ captured.

On the measurement, a granted IFP Energies Nouvelles patent (US 10,137,404 B2) reports gas-treatment testing in 316L stainless under normal operating conditions with no anti-degradation or anti-corrosion additives: a 30 wt% MEA solution degraded “at a rate of the order of 1.5 kg MEA per ton of CO₂ captured,” and when the concentration was raised to 40 wt%, “the amine degradation rate was multiplied by two, thus reaching 3 kg MEA per ton of CO₂.”

The emissions question regulators are circling

Degradation does not only cost money; it produces compounds that leave the plant. Amine carryover from the absorber, plus degradation products including ammonia, aldehydes, nitrosamines and nitramines, is an active research and regulatory topic for large flue-gas capture installations. Nitrosamine and nitramine formation in particular depends on the combination of amine, NO_x in the flue gas, oxygen and heat over time, which is why it is a process-design and emissions-control question at scale rather than a property of amine sitting in a drum.

Practically, this is why new designs keep reaching for blends, hindered amines and water-wash sections, and why emissions monitoring is increasingly written into permits. If you are scoping a capture project, budget for the wash section and the solvent-management plan from the start rather than treating them as retrofits.

What this means if you actually buy MEA

We will be straight about scope, because it decides whether we are useful to you.

Alliance Chemical stocks monoethanolamine in technical grade and ACS grade, in packages from 1 quart up to 330-gallon IBC totes. That is the right footprint for a pilot skid, a bench or wetted-wall rig, a university or national-lab programme, acid-gas treating top-up, pH adjustment, corrosion-inhibitor formulation and chemical synthesis. MEA ships as UN2491, hazard class 8, packing group III.

If you are charging a utility-scale absorber, your amine arrives by railcar or isotainer on a term contract, and we are not the right supplier for that inventory. We would rather tell you so than sell you the wrong package. Where we are useful at that scale is the bench and pilot work that sits upstream of it, and the top-up volumes that sit alongside.

For the broader chemistry and application picture, see our pillar guide to MEA in carbon capture and green chemistry, and the in-depth guide to monoethanolamine for properties, handling and storage. You can also browse all monoethanolamine packages.

Frequently asked questions

What is CarbonBridge and why does it matter for carbon capture?

CarbonBridge is a joint venture between industrial gas maker Messer and energy and logistics firm Ambrian Energy that cleared European antitrust review at the end of August 2026. It will build Germany’s first CO₂ export terminal at Bremen, taking captured CO₂ by railcar from heavy industry including chemical makers and shipping it to geological storage under the North Sea. Capacity is 2.3 million metric tons a year at opening with expansion toward 4 million contemplated, and operation is scheduled for as early as 2030. It matters because capture projects have been limited less by absorber chemistry than by having nowhere to send the product.

Why is monoethanolamine still the reference solvent for CO₂ capture?

Three reasons compound. At 61.08 g/mol MEA is the lightest amine that still performs, so a kilogram delivers more reactive amine groups than any heavier alternative. Its reaction kinetics with CO₂ are fast, which keeps absorbers smaller. And it is cheap and universally available. Newer solvents beat it on regeneration energy and on resistance to oxidation, but MEA remains the benchmark every alternative is measured against, nearly a century after Robert Bottoms patented amine scrubbing in 1930.

How much MEA does a capture plant consume per tonne of CO₂?

Measured degradation in a 30 wt% MEA solution running without anti-degradation or anti-corrosion additives is on the order of 1.5 kg of MEA per tonne of CO₂ captured, and raising the solution to 40 wt% roughly doubles that to about 3 kg per tonne, according to testing reported in IFP Energies Nouvelles patent US 10,137,404 B2. For comparison, the National Petroleum Council’s CCUS roadmap regards losses equivalent to $1 to $2 per tonne of CO₂ as acceptable at an amine price of $2/kg, which is roughly 0.5 to 1.0 kg per tonne. Closing that gap is the job of reclaimers, oxidation inhibitors and solvent blends.

Why does a stronger amine solution consume more amine?

Concentration raises the rate of the degradation chemistry itself. A more concentrated solution circulates less water for the same CO₂, which is the efficiency argument for it, but the amine spends its time in a more aggressive environment and both oxidative and thermal degradation accelerate. The IFPEN measurement puts the effect at roughly a doubling between 30 and 40 wt% under otherwise normal operating conditions. It is a genuine trade-off rather than a free efficiency gain.

What is the maximum CO₂ loading of MEA, and why is it capped?

The theoretical maximum is 0.5 mol CO₂ per mol of amine. A primary amine such as MEA reacts with CO₂ to form a carbamate, and that reaction liberates a proton which a second amine molecule must accept, giving an overall stoichiometry of two amines per CO₂. The cap is therefore written into the reaction mechanism rather than into the equipment. Tertiary amines such as MDEA and hindered amines react by a bicarbonate route that lifts the ceiling, at the cost of slower kinetics, which is why blends are common.

What grade and package of MEA should I buy?

Technical grade is the working choice for acid-gas treating, pH adjustment, corrosion-inhibitor formulation and general synthesis. ACS grade is appropriate for analytical work, method development and reference solutions where the specification has to be defensible. Alliance Chemical stocks both from 1 quart through 330-gallon IBC totes; MEA ships as UN2491, hazard class 8, packing group III. Utility-scale absorber inventories are bought by railcar on term contracts and are outside what a packaged distributor should quote.

References and sources

• Craig Bettenhausen, “Business Watch: Symrise finds buyer for terpene unit, and more,” Chemical & Engineering News, September 2026 — CarbonBridge antitrust clearance, capacity, schedule, and Messer’s installed amine-plant count.
• R. R. Bottoms, US Patent 1,783,901, “Process for separating acidic gases,” granted 2 December 1930, assigned to The Girdler Corporation.
• National Petroleum Council, Meeting the Dual Challenge: A Roadmap to At-Scale Deployment of Carbon Capture, Use, and Storage, Appendix E: Mature CO₂ Capture Technologies, 12 December 2019 — oxidative and thermal degradation, T_max, metal catalysis, amine-loss economics.
• IFP Energies Nouvelles, US Patent 10,137,404 B2, “Method of absorbing acid compounds contained in a gaseous effluent using an amine-based aqueous solution,” granted 27 November 2018 — measured MEA degradation rates at 30 and 40 wt%.