Preparation of low-cost hierarchical porous cellulose aerogels and their adsorption performance for pure CO2 and CO2 in the simulated cement plant flue gas

Developing advanced materials for CO 2 adsorption is of great significance to reduce global warming caused by the continuous increase in CO₂ emissions. In the present work, hierarchical porous cellulose aerogels were prepared via the sol-gel and freeze-drying techniques using low-cost cellulose powder. The morphology, pore structure, phase, surface chemical composition, and adsorption performance for pure CO 2 and CO 2 in the simulated cement plant flue gas were investigated in detail. The results show that the obtained cellulose aerogels possess a high specific surface area, ranging from 62.45 to 124.9 m²/g, and exhibit a hierarchical porous structure. The samples with a cellulose powder concentration of 6wt% and undergoing the freeze-thaw process (denoted as 6CAF) demonstrates a maximum static adsorption capacity of 2.5 mmol/g at 25°C for pure CO 2 , and a breakthrough capacity of 3.5 mmol/g for the CO 2 in the simulated cement plant flue gas at 25°C. Upon the cycling adsorption, the 6CAF cellulose aerogels manifest desirable reusability except for the first cycle, where the residual sodium hydroxide from the preparation process plays a critical role in the CO 2 adsorption, leading to a chemical adsorption of CO 2 . The physical adsorption of CO 2 dominates in the subsequent cycles. This work provides a low-cost alternative for CO 2 adsorption, especially for that in the simulated cement plant flue gas.