Development of CO2-to-CO Conversion Catalyst... Opens Path for Low-Cost Production of Versatile Carbon Monoxide Worker

Development of Affordable Catalyst that Selectively Converts Greenhouse Gas (CO2) into Carbon Monoxide (CO)
Identification of Factors Enhancing CO Generation Reaction Selectivity of Tin Catalyst
Joint Research Team from UNIST and KAIST Publishes Cov

Construction catalyst fabrication process.

[Asia Economy Yeongnam Reporting Headquarters Reporter Kim Yong-woo] A tin (Sn) catalyst that converts carbon dioxide (CO2), the main culprit of global warming due to greenhouse gases, into carbon monoxide (CO) has been developed.

This overturns the more than 50-year consensus that tin catalysts are unfavorable for carbon monoxide production, attracting significant attention from the academic community.

This research is significant in that it proposes a cheap and efficient method to produce versatile carbon monoxide, which is widely used in the manufacture of fuels, plastics, detergents, and adhesives.

The research team led by Professor Kwon Young-guk of the Department of Energy Chemical Engineering at Ulsan National Institute of Science and Technology (UNIST), in collaboration with Professors Kang Seok-tae and Kim Hyung-joon of KAIST, announced on the 20th that they developed an integrated catalyst (electrode) based on inexpensive tin and carbon supports.

This catalyst exhibits very high reaction selectivity, producing only carbon monoxide, resulting in a carbon monoxide production efficiency more than 100 times that of existing tin catalysts.

It has also been academically recognized for demonstrating that reaction selectivity can be controlled using an electric field.

Professor Kwon Young-guk, UNIST.

Tin (Sn) has the advantage of being cheaper than gold- and silver-based catalysts used for carbon monoxide production. However, when tin is used in carbon dioxide conversion reactions, more formic acid is produced than carbon monoxide. The reaction selectivity for producing carbon monoxide is not high.

The joint research team developed a catalyst that can selectively produce carbon monoxide by using carbon nanotubes together with tin.

When nanometer-sized (nm, 10^-9 meters) tin particles attach to the surface of carbon nanotubes, changes in the electric field promote the reaction that generates carbon monoxide.

This is because the electric field changes around the tin particles help carbon dioxide reactants adhere better to the tin particle surface.

On the other hand, the reaction producing formic acid is not affected by the electric field changes induced by the carbon nanotubes.

Professor Kang Seok-tae, KAIST.

Since the formic acid generation reaction and the carbon monoxide generation reaction compete, using the developed catalyst allows for increased carbon monoxide production while suppressing formic acid formation.

Professor Kwon Young-guk said, “It has been a view for over 50 years that tin catalysts promote formic acid production, but by controlling the electrode electric field, we overturned this conventional wisdom.”

He explained, “This research is significant as it is the first to demonstrate how electric fields can be utilized in designing catalysts for carbon dioxide conversion reactions.”

The newly developed integrated support catalyst can be easily manufactured using a firing method similar to pottery making.

A semi-liquid (sol) mixture composed of carbon nanotubes, tin nanoparticles, and polymers is formed into a hollow cylindrical electrode and then solidified at high temperature.

The hollow structure facilitates smooth diffusion of the carbon dioxide gas reactant. Additionally, the tin particles and the carbon nanotube support are firmly bonded through a sintering reaction, solving the problem of tin detaching from the electrode surface.

Professor Kim Hyung-jun, KAIST.

The research team also elucidated the principle by which carbon monoxide, rather than formic acid, is produced on the tin-based catalyst through theoretical calculations.

According to these calculations, carbon nanotubes increase the electron density on the tin surface. The increased electron density creates conditions favorable for carbon dioxide to adsorb well onto the tin surface.

Furthermore, the electric field formed on the tin surface promotes the conversion of adsorbed carbon dioxide into carbon monoxide, while suppressing the formation of formic acid, which is insensitive to the electric field.

This research was published on September 11 as an inside cover paper in ‘ACS Energy Letters,’ a world-renowned journal in materials engineering and electrochemistry. The study was supported by the Next-Generation Carbon Resource Utilization Project (NCUP) and the Future Materials Discovery Project.

ACS Energy Letters cover page.

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