Nitto, the Osaka-based manufacturer of high-performance materials, is in the final stages of testing polymer CO2 separation membranes on real exhaust gas at a pilot unit in Shiga, central Japan, with commercialization targeted for the coming years. The technology addresses a segment of the carbon capture market that incumbent solvent-based systems have largely bypassed: post-combustion capture at industrial boilers and other small to medium emission sources.

The scale of the gap is stark. The International Energy Agency projects that global CO2 capture capacity must reach roughly 3.74 billion tonnes by 2050 to meet climate goals — approximately 85 times the volume captured in 2022. Membrane systems, which run on electricity rather than thermal energy, are one of the technology pathways being scaled to close it.

Why size-based membranes fail

Since the 1990s and 2000s, chemical absorption using aqueous amine solutions has dominated carbon capture. CO2 in exhaust gas reacts with an amine solvent, forming a soluble compound that separates it from nitrogen and other gases. But regenerating that solvent requires substantial thermal energy, confining the economics to large point sources such as steel and power plants. Smaller facilities — materials and chemical plants among them — face costs and operational hurdles that include secondary emissions from thermal solvent regeneration.

"Major industrial sources have been the primary focus of innovation and investment," says Terukazu Ihara, general manager of separation technology research at Nitto. "But it's also important to address smaller operations, which often require different technological approaches."

Conventional membrane approaches hit a physical limit in this application. "Most conventional membranes act as molecular sieves, separating gases by size," explains Ihara. "However, in the exhaust streams we target, CO2 and nitrogen molecules are nearly identical in size, requiring a fundamentally different approach."

Inorganic membranes with uniformly arranged nanopores lose performance when molecule sizes converge. Metal–organic frameworks offer high size and chemical selectivity but remain costly and difficult to fabricate uniformly at scale, limiting commercial viability, according to Ihara.

Solution–diffusion instead of sieving

Nitto's answer is a high-performance polymer membrane that separates by chemistry, not geometry. Molecular units in the membrane interact strongly with CO2, letting it dissolve preferentially while limiting nitrogen solubility. A pressure gradient across the membrane drives dissolved CO2 through, where it can be collected. "This solution–diffusion mechanism enables selective and efficient CO2 separation," says Ihara.

The company draws on more than five decades of membrane manufacturing, originally built around water-treatment technologies. "This background has given us a strong foundation for deploying our membrane technologies in decarbonization," says Yuya Kitagawa, director of Nitto's Corporate Business Development Division.

The membranes are assembled into spiral-wound modules — the same configuration Nitto uses in water treatment. Flat membrane sheets wrap around a central collection tube, maximizing surface area in a compact structure and channeling separated CO2 to the core. Achieving high flux and selectivity in the multilayer structure requires coating the membrane with ultrathin, defect-free layers.

At the Shiga pilot, cylindrical modules 20 centimetres wide and 1 metre long are "installed in the plant and act much like an air purifier filters," says Kitagawa. The system runs two stages rather than a single pass: a single-stage membrane system cannot achieve sufficient CO2 purity, while a two-stage configuration reaches purity high enough for applications such as liquid CO2 and dry ice. Underground storage demands still higher concentrations, achievable by pairing the membrane with pressure swing adsorption or similar processes.

Commercial runway and open questions

Nitto aims to commercialize the membrane in the coming years, targeting post-combustion capture from industrial boiler exhaust. "The development of low-cost, highly efficient CO2 capture technologies has become an urgent priority," says Ihara.

Deployment at scale, however, hinges on demand for captured carbon. "Some applications are already available, such as CO2 for carbonated beverages, but large volume markets like synthetic fuels made from captured CO2 are still emerging," says Kitagawa. Storage infrastructure, regulatory frameworks and the costs of capture and transport remain major hurdles, he adds.

The company is expanding partnerships to de-risk the technology, including a collaboration with an overseas startup on carbon-capture solutions for medium-scale emission sources such as power plants. Its 2022 pledge to pursue only technologies aligned with environmental, social and governance principles frames the longer-term program, which includes a concept for combining captured carbon with hydrogen-based fuels and returning the resulting energy carriers to factories — a circular carbon flow for industrial sites.

"Our goal is to develop a portfolio of technologies that together can enable 'carbon neutrality'," says Kitagawa.

The near-term milestone to watch is the completion of real-flue-gas validation at Shiga and the transition from pilot to first commercial installations on industrial boilers. Beyond that, market uptake will be decided by offtake: whether emerging high-volume uses for captured CO2, chiefly synthetic fuels, mature into bankable demand before the decade's capture-capacity targets slip further out of reach.