The fastest carbon dioxide sensor heralds a new era for direct air capture – Eurasia Review


Researchers at Tokyo Metropolitan University have developed a new carbon capture system that removes carbon dioxide directly from the atmosphere with unprecedented performance. Isophorone diamine (IPDA) in a “liquid-solid phase separation” system has been shown to remove carbon dioxide at low concentrations from the atmosphere with 99% efficiency. The compound is reusable with minimal heating and at least twice as fast as existing systems, an exciting new development for direct air capture.

The devastating effects of climate change are being felt around the world, with an urgent need for new policies, lifestyles and technologies that will reduce carbon emissions. However, many scientists see beyond a goal of net zero emissions to a “beyond zero” future where we can actively reduce the amount of carbon dioxide in the atmosphere. The field of carbon capture, the removal and then storage or conversion of carbon dioxide, is growing rapidly, but hurdles remain before it can be deployed on a large scale.

The biggest challenges come from efficiency, especially in handling atmospheric air directly in so-called Direct Air Capture (DAC) systems. Carbon dioxide concentrations are such that chemical reactions with sorbents are very slow. There is also the difficulty of re-extracting the carbon dioxide in longer-lasting capture and desorption cycles, which can be very energy-intensive in themselves. Even major efforts to build DAC plants, such as those using potassium hydroxide and calcium hydroxide, suffer from serious efficiency and recovery cost issues, making the search for new processes particularly urgent.

A team led by Professor Seiji Yamazoe of Tokyo Metropolitan University studied a class of DAC technology known as liquid-solid phase separation systems. Many DAC systems involve bubbling air through a liquid, with a chemical reaction occurring between the liquid and carbon dioxide. As the reaction progresses, more of the reaction product accumulates in the liquid; this makes subsequent reactions increasingly slow. Liquid-solid phase separation systems offer an elegant solution, where the reaction product is insoluble and comes out of solution as a solid. There is no accumulation of product in the liquid and the reaction rate does not slow down much.

The team focused their attention on liquid amine compounds, modifying their structure to optimize reaction speed and efficiency with a wide range of carbon dioxide concentrations in air, from about 400 ppm to 30 percent. . They found that an aqueous solution of one of these compounds, isophorone diamine (IPDA), could convert 99% of the carbon dioxide in the air into a solid precipitate of carbamic acid. Importantly, they demonstrated that the dispersed solid in solution only required heating to 60 degrees Celsius to completely release the captured carbon dioxide, recovering the original liquid. The rate at which carbon dioxide could be removed was at least twice as fast as leading DAC lab systems, making it the fastest carbon dioxide capture system in the world today for the treatment of low concentration carbon dioxide in the air (400 ppm).

The team’s new technology promises unprecedented performance and robustness in DAC systems, with broad implications for large-scale deployed carbon capture systems. Beyond improving their system, their vision of a world “beyond zero” now turns to how the captured carbon can be used efficiently, in industrial applications and household products.

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