Low-temperature regeneration through chemically triggered physical CO2 absorption

Anhydrous TMHDA-EG enables tertiary-amine-catalyzed CO 2 absorption and regeneration at 55 °C. • Alcohol-CO 2 reactions create new oxygen sites that promote quasi-physical CO 2 uptake. • Demonstrated stable cyclic regeneration of the absorbent under low-grade heat and light irradiation. Reducing the regeneration temperature is an effective way to decrease the energy consumption in carbon dioxide capture. The anhydrous absorbent prepared by blending tertiary amines with ethylene glycol (EG) can form an unstable chemical structure with CO 2 , constituting a quasi- physical absorption system that can be efficiently regenerated below 60 °C or under light conditions. Experimental results and theoretical analysis reveal that glycolate (EGCOO − ), which is produced through tertiary-amine catalysis, can boost additional CO 2 uptake physical absorption Since EGCOO − is inherently unstable and the physically absorbed CO 2 is easily released, N , N , N ′, N ′-tetramethyl-1,6-hexanediamine (TMHDA)-EG system maintains effective absorption/desorption cycling within 30 °C–55 °C, making it well-suited for CO 2 capture and release under conditions with pronounced diurnal temperature fluctuations. The absorbent could be regenerated with a solar simulator, showing excellent energy adaptability in industries. Such absorbents may serve as CO 2 carriers for greenhouse agriculture on Earth or for future extraterrestrial bases, enabling regulation of CO 2 concentrations to promote indoor agricultural productivity. Download: Download high-res image (76KB) Download: Download full-size image