CO₂ absorption of anhydrous colloidal suspension based silica nanospheres with different microstructures

Liquid absorption and solid adsorption technologies have been researched and reported widely for CO₂ capture. Combining the advantages of these two capture materials, a novel anhydrous colloidal suspension was synthesized by dispersing amine-modified microporous silica nanospheres in 2-[2-(dimethylamino) ethoxy] ethanol. In this study, solid, hollow, and porous silica nanospheres with different internal pore structures were synthesized and characterized. The effects of the silica nanosphere microstructures on diethylenetriamine loading and CO₂ absorption in anhydrous colloidal suspensions were studied. Due to a more developed pore structure, the hollow and porous silica-based absorbents possessed stronger amine loading capacities compared to solid silicon-based absorbent, and the best absorption performance was an absorption capacity of 1.2543 mmol/g at a pressure of 150 kPa and a temperature of 300 K. The results indicated that pore structure had a significant influence on the absorption property, and the porous silica-based absorbent was more favorable for CO₂ absorption than solid and hollow silica-based absorbents. Moreover, the pseudo-second-order model was successful in predicting the CO₂ absorption process in colloidal suspensions.