Capturing 0.04% Atmospheric CO₂ Even at Minus 10°C... Korean Adsorbent Developed [Reading Science]

Korea University Develops Pellet-Type Adsorbent Suited for Real-World Devices
Stable Performance at Low Temperatures and Humidity
Increasing the Potential for Commercializing Direct Air Capture

A technology has been developed that allows for the direct capture of carbon dioxide (CO₂), which makes up only 0.04% of the atmosphere, even in cold environments as low as minus 10 degrees Celsius. By producing the adsorbent in pellet form, which is easier to load into actual devices compared to powder, and confirming stable performance across various temperatures and humidity levels, the research team has increased the viability of on-site application for direct air capture (DAC) technology.

Korea University announced on August 19 that the research team led by Professor Yongtae Kang of the Department of Mechanical Engineering has developed a pellet-type CO₂ adsorbent by combining carbon nanotubes (CNTs) and amines with silica nanoparticles.

Overview of the Mass Production of CO2 Pellet Adsorbents and Evaluation of the Low-Temperature Direct Air Capture System. The pellet adsorbent for direct air capture demonstrates verified performance even in sub-zero environments, enables mass production, and exhibits high energy efficiency. Provided by the research team.

To achieve carbon neutrality, it is not only necessary to capture CO₂ emissions at sources such as factories or power plants, but also to remove CO₂ that has already dispersed into the atmosphere. DAC is a technology that uses large fans to draw in air, selectively capturing and separating only the CO₂.

The challenge is that atmospheric CO₂ concentration is only about 0.04%, or 400 ppm. It is necessary to selectively capture extremely small amounts of CO₂, and, in order to ensure economic viability, reduce the energy required for the regeneration process that detaches the captured CO₂ to reuse the adsorbent.

The research team combined amines, which selectively capture CO₂, and carbon nanotubes with silica nanoparticles. Carbon nanotubes reinforce the structure of the adsorbent like a backbone and simultaneously facilitate the transfer of heat and CO₂.

In particular, the team used a "self-assembly" method, whereby carbon nanotubes and silica nanoparticles intertwine naturally to form a supporting structure. This enables the formation of powder materials into uniform-sized pellets without the use of adhesives. The aim is to mitigate issues such as materials loss or pressure drop that can occur when powder adsorbents are applied to actual DAC systems.

Performance Maintained Even at Minus 10 Degrees Celsius and Under Changing Humidity

The researchers evaluated the adsorbent's performance by varying temperature and humidity from minus 10 degrees Celsius to plus 20 degrees Celsius. As a result, the pellet maintained its shape and performance even after repeated cycles of CO₂ adsorption and regeneration. The CO₂ capture performance was also restored after regeneration.

The team went beyond verifying the intrinsic performance of the adsorbent material, developing a predictive model for performance under real-world environmental changes and conducting a system energy evaluation. They explained that, by taking into account varying temperatures and humidity levels across different regions and seasons, the optimized operating conditions for DAC systems can be set, allowing for the simultaneous optimization of both material and process.

Research team photo. Yongtae Kang, Professor of Mechanical Engineering at Korea University (left, corresponding author), Younghwan Seo, PhD candidate (first author). Courtesy of Korea University

However, further research is required before commercialization. The research team plans to lower the desorption temperature required to release CO₂ from the adsorbent and to implement heat recovery technology to reduce the energy needed for regeneration. They are also exploring photothermal conversion technology to supply regeneration heat by converting light into thermal energy. Additionally, long-term durability tests and field demonstrations in outdoor environments are planned.

Professor Yongtae Kang of Korea University commented, "The significance of this research lies not only in developing high-performance powder materials, but also in shaping them into forms suitable for actual devices, operating them under low temperature and humidity conditions, and evaluating the entire process including energy use. Moving forward, we aim to decrease the thermal energy required for regeneration and broaden long-term field demonstrations, developing direct air capture technology applicable to a wide range of climates."

The research results were published in Volume 119 of the international journal 'Journal of Energy Chemistry' in the field of applied chemistry.

This content was produced with the assistance of AI translation services.