From PET waste to CO₂ sorbent: how BAETA turns two crises into one solution

A research team at the University of Copenhagen has demonstrated a simple chemical process that converts low-grade PET plastic waste – the type that is rarely recycled – into a solid material that captures CO₂ from flue gas and ambient air alike. The work, published on 5 September 2025 in Science Advances, addresses two problems with one reaction. It is also a textbook example of the kind of cross-domain innovation that the broader Power-to-X ecosystem depends on.

How BAETA is made

The starting material is polyethylene terephthalate (PET) – the plastic used in beverage bottles, food packaging, and textiles. Lead author Margarita Poderyte and co-author Jiwoong Lee, with their colleagues, developed an aminolysis reaction that breaks PET down using 1,2-ethylenediamine, a relatively benign reagent. No solvents and no catalysts are required. The reaction runs at 60 °C for 24 hours, or at room temperature over up to two weeks.

The output is a solid powder named BAETA (bis-aminoamide of ethylenediamine and terephthalate) plus related oligomers. From one kilogram of consumer PET waste – cut and rinsed, no other pretreatment – the team produced approximately 800 grams of BAETA material. The conversion has been demonstrated on bottles, food packaging, toy stuffing, and textiles. Mixed and degraded PET sources work too, which is precisely the fraction that current mechanical recycling cannot process economically.

What the material can do

The reported performance figures are notable. BAETA has a CO₂ capture capacity of up to 3.4 moles per kilogram. It is thermally stable above 250 °C and operates effectively between ambient temperature and around 170 °C. It selectively captures CO₂ from flue gas with concentrations between 5 and 20 percent, and also from ambient air at around 400 parts per million – the regime relevant for direct air capture – even under humid conditions.

The comparison the authors invite is with monoethanolamine (MEA), the standard liquid amine used in many current post-combustion CO₂ capture installations. MEA degrades at elevated temperatures, is energy-intensive to regenerate, and carries handling and environmental concerns. BAETA, by contrast, is a solid that can be pressed into pellets without performance loss and retains its capacity over many sorption cycles in the reported tests.

Honest caveats

The work is early stage. Laboratory-scale demonstration is a long way from industrial deployment. Independent commentary in Chemical & Engineering News noted that future studies will need to assess the environmental fate and safe end-of-life handling of BAETA, as for any amine-based sorbent. The team is currently running depolymerisation at scales up to two kilograms and testing how BAETA reacts to common flue gas pollutants such as sulphur oxides and nitrogen oxides. Lee has stated the goal of demonstrating multi-kilogram CO₂ capture per year within two years.

The capture capacity is also competitive but not exceptional in absolute terms – some engineered amine sorbents and metal-organic frameworks report higher figures. The interesting feature of BAETA is not raw capacity. It is the combination of waste-derived feedstock, simple synthesis, and broad operating window.

The Power-to-X connection

The scale-up project is being funded through the VILLUM Power-to-X Accelerator, a Danish research programme that funds technologies enabling the transition to renewable energy carriers and chemicals. That is not incidental. Carbon capture is one of the structural enablers of Power-to-X: synthetic fuels, e-methanol, e-methane, e-naphtha and most CO₂-based chemicals require a source of recycled carbon, ideally biogenic or atmospheric. Capture cost is one of the largest line items in any e-fuel economic model.

A sorbent material that uses waste plastic as feedstock and operates across both point-source and direct air capture regimes is therefore directly relevant to Power-to-X deployment. If BAETA scales, it potentially reduces the marginal cost of recycled CO₂ at the same time as it diverts low-grade plastic from landfill or incineration. Whether that potential is realised will depend on industrial scale-up, energy balance over many regeneration cycles, and competition from established alternatives.

SPIN Perspective

It is easy to be cynical about every new breakthrough material announcement – most do not make it past the lab bench. The Copenhagen team’s contribution is sober: a peer-reviewed paper, characterised material, a clearly stated scale-up path, and explicit awareness of the open environmental and engineering questions. That is how Power-to-X technology actually advances – not through hype cycles, but through incremental, well-documented work that lowers the cost of the building blocks.

Switzerland has a strong base of academic and industrial work on CO₂ capture and utilisation. Climeworks pioneered commercial direct air capture; the EPFL Wallis CO₂-recycling project is exploring waste-incinerator CO₂ streams for fuels, plastics and building materials; multiple Swiss companies are working on alternative sorbents and processes. The BAETA result is a useful benchmark and a reminder that capture innovation is happening in many places at once. Cooperation across these efforts – not competition between them – is what will eventually move CO₂ capture from showcase to commodity.

Sources: Science Advances, University of Copenhagen, C&EN, Chemistry World.

🤖 AI transparency: This text and its visual were created using AI, reviewed and approved by a human.