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An energy-efficient CO2 conversion catalyst technology using both light and heat

The issue of climate change caused by global warming is much more serious than many imagine. The world is already experiencing difficulties with natural disasters, localized downpours, drought, torrential rain, and heavy snow. This has sparked much research on solutions to reduce carbon dioxide (CO2). Carbon dioxide is the main cause of global warming and climate change, and there is an urgent need to develop efficient technologies to address the issue.

Technology research to obtain a high-performing catalyst

Professor Hyunjoo Lee and her research team were studying plasmonic catalysts when they noticed that light irradiation substantially decreased the reaction temperature. At the time, they were testing the ethanol dehydrogenation reaction. They concluded that if the same phenomenon was achieved with the CO2 conversion reaction, they could dramatically reduce the total energy cost involved in converting CO2 into more useful compounds. Many research teams are investigating methods to isolate, collect, and store CO2 from the air, but there has been little success in finding a clear method for stable storage of the vast amounts of CO2 collected. This created a need to convert CO2 into more valuable compounds using chemical methods, and the strategy was to form a cycle that converts those compounds back into CO2. The process of converting CO2 into compounds requires a catalyst. In other words, it was necessary to engage in technology research to obtain a high-performing catalyst to convert CO2, the most thermodynamically stable carbon substance in air, into other compounds.

Efficient energy conversion through catalyst technology

The research team published a study in which it found that when an Ru catalyst was used, CO2 was strongly bound to the Ru surface and the bound complex absorbed light to enable easy breakdown of CO2 and conversion into CH4. Ru is believed to be generally unaffected by light. However, the study found that the Ru-CO2 complex can absorb light, and in such cases, CO2 can be broken down easily at much lower temperatures than when there is no light. These findings are expected to significantly contribute to the easy and low-energy production of CH4. In the future it may also be very useful for in-situ fuel production, whereby the hydrogen and waste carbon dioxide produced from the use of wind/photovoltaic power is used to synthesize methane and other fuels where and when necessary.
When converting CO2 that has been collected into high value-added compounds, factors such as the presence of large amounts of impurities in the CO2 and CO2 concentration have a major influence on catalyst action. It is possible to produce high-purity CO2 through various separation processes, but such methods have high separation costs. A catalyst that can directly convert low-purity, low-concentration CO2 into high value-added compounds would significantly reduce the total cost of the overall CO2 conversion reaction. The research team plans to continuously develop catalysts to selectively target and convert CO2 from a mixture of various substances using little energy.

Prof. Hyunjoo Lee
2018 KI Annual Report

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