Researcher team finds a more energy efficient method to capture CO2

Researchers from Kyoto University’s Institute for Integrated Cell-Material Sciences (ICEMS) report a new and energy efficient option to selectively extract specific gas molecules from gas mixtures. The method specifically interacts and captures CO2, which helps mitigate climate change.

Polymer framework to extract gas molecules

Susumu Kitagawa, chemist and leader of the research team explained that the work demonstrated exceptional molecule recognition and separation performance by deliberately organizing pore geometry, structural flexibility and molecular-level binding sites within a porous coordination polymer (PCP).

PCP, also known as metal-organic frameworks (MOFs), have metal ions or clusters held together by organic (carbon-based) linker groups.

Choosing different metallic components and adjusting the size and structure of the organic groups can create a huge variety of crystalline materials containing pores with finely controlled sizes, structures and chemical binding capabilities.

New PCP with channel system to capture CO2

The new research work goes beyond – with pores that adapt when desired molecules bind to them.

The team designed a flexible PCP with a corrugated channel system that can interact with and adsorb CO2 molecules by selectively opening pores that acts as gates, allowing only CO2 to pass through.

Researchers developed a new flexible porous material that opens gates and adsorbs only carbon dioxide among various similar gas molecules.

“Capturing CO2 is particularly challenging, due to the molecule’s relatively small size and low affinity for many adsorptive materials,” explained Ken-ichi Otake, a researcher of the team.

Technical term for the result from the interaction between CO2 and PCP is exclusion discrimination gating. It means that binding of molecules chosen as the extraction target initiates a synergistic structural change that enhances the binding and opens up the solid phase structure to let the bound molecule enter.

More energy efficient for large-scale CO2 extraction

The team demonstrated their system by using it to gather CO2 from mixtures of many industrially significant molecules, including nitrogen, methane, carbon monoxide, oxygen, hydrogen, argon, ethene and ethyne.

The process is significantly more energy efficient than existing options, over a full cycle of selective gas capture and regeneration. This support low-carbon industrial processes and development of more sustainable gas separation technologies.

Energy efficiency will also be vital for power cycle of extraction, release and storage in large-scale climate engineering to extract carbon dioxide from the atmosphere.