Photothermal Release of CO₂ Using Carbon/Silica Composite toward Direct Air Capture

Abstract

In the DAC process, solid adsorbents with amine can be used for rapid and large CO2 adsorption, while it consumes high energy for CO2 release by heating. In this work, we developed a photothermal adsorbent that can release CO2 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 CO2, approximately 45 mg-CO2 g–1. However, the photothermal adsorbent can release 37.3 mg-CO2 g–1 for 90 min, while the nonphotothermal one released few amounts of CO2 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 CO2 release from the adsorbent.

Recent Progress on Porous Carbons for Carbon Capture

“…Furthermore, the temperature of the photothermal adsorbent rose from 25.0 to 59.3 °C, but the nonphotothermal adsorbent only had an 8.7 °C increase in temperature. Consequently, light irradiation raises the temperature of the material that absorbs light, which leads the adsorbent to effectively release CO 2 …”