Photothermal Release of CO<sub>2</sub> Using Carbon/Silica Composite toward Direct Air Capture
Taishi Kataoka, Yasuhiko Orita, Yusuke Shimoyama
Abstract
In the DAC process, solid adsorbents with amine can be used for rapid and large CO 2 adsorption, while it consumes high energy for CO 2 release by heating. In this work, we developed a photothermal adsorbent that can release CO 2 by light irradiation for an energy-saving DAC process. To obtain the photothermal adsorbent, carbon materials, which are often used as a light-absorbing material, are combined with a polyamine-impregnated silica adsorbent. Both photothermal adsorbent with carbon material and nonphotothermal adsorbent without carbon material adsorbed almost the same amount of CO 2, approximately 45 mg-CO 2 g –1 . However, the photothermal adsorbent can release 37.3 mg-CO 2 g –1 for 90 min, while the nonphotothermal one released few amounts of CO 2 by light irradiation of 3 kW m –2 . Furthermore, the temperature of the photothermal adsorbent increased from 25.0 to 59.3 °C by light irradiation, while the increase in the temperature was only 8.7 °C for the nonphotothermal one. Hence, light irradiation led to the temperature increase by the light-absorbing material, achieving the efficient CO 2 release from the adsorbent.