SnO2/ATP catalyst enabling energy-efficient and green amine-based CO2 capture

Abstract

CO2 capture using aqueous amine solutions necessitates intensive heat duty because the temperature of solvent regeneration required to decompose the carbamate is>120 °C. In this work, we reported a SnO2 modified attapulgite (SnO2/ATP) solid acid catalyst to accelerate CO2 desorption in a rich 5 M monoethanolamine (MEA) solution at 88 °C. The SnO2/ATP catalyst with improved Brønsted acid sites and strong acid sites worked better than SnO2 and ATP. Particularly, utilizing 1/2-SnO2/ATP increased the CO2 desorption rate and desorbed CO2 by 265 and 222 %, respectively, as compared to CO2 desorption without a catalyst. The relative heat duty could be reduced by about 52 % by using 1/2-SnO2/ATP to regenerate the rich MEA solution, and its catalytic performance was superior to most reported solid catalysts for this purpose. FT-IR technique was employed to confirm the catalytic effect and a possible catalytic CO2 desorption mechanism was suggested. Additionally, 12 CO2 absorption–desorption cyclic tests were conducted to certificate the recyclability of 1/2-SnO2/ATP. These findings demonstrated that SnO2/ATP catalyst had significant potential for industrial use in low-energy and green amine-based CO2 capture processes. This study provides a practical strategy for utilizing efficient, affordable and environmentally benign solid acid catalysts for CO2 desorption, thereby advancing energy-efficient CO2 capture technology.