Porous solids for CO2 adsorption: Insights of Cellulose and Chitosan-Based Carbon Aerogel

Kurzfassung

The climate crisis, driven by global warming and the continuous increase in atmospheric greenhouse gas (GHG) concentrations, underscores the urgent need for efficient technologies capable of mitigating CO₂ emissions. Among the available separation techniques, gas adsorption on porous solid materials has emerged as a particularly attractive strategy due to its low operational cost, simplicity, recyclability, and absence of secondary environmental impacts. In this framework, aerogels constitute a highly promising class of adsorbents, characterized by exceptionally high specific surface areas, well-defined pore architectures, and robust thermal and mechanical stability. When synthesized from renewable biopolymers such as cellulose and chitosan, aerogels additionally reinforce circular-economy principles and can exhibit a lower carbon footprint compared with conventional activated carbons. This study aims to synthesize cellulose- and chitosan-based carbon aerogels and to evaluate the influence of polymer concentration, acid type and concentration and subsequent carbonization on their porous morphology and CO₂ adsorption performance. Cellulose aerogels were produced using cellulose mass concentrations of 3%, 5%, and 7% with hydrochloric and acetic acids in the coagulation, while chitosan aerogels were prepared with 3%, 4%, and 5% using different acetic acid concentrations during the dissolution. All samples will be subjected to systematic characterization using nitrogen adsorption–desorption isotherms at 77 K to determine specific surface area, pore size distribution, total pore volume and microporosity metrics. These analyses will be performed both before and after carbonization to elucidate structural modifications induced by thermal treatment. The expected outcomes include: (i) a comparative assessment of non-carbonized and carbonized aerogels with respect to textural properties derived from N₂ isotherms; (ii) quantitative correlations linking polymer concentration and acid conditions to surface area, pore volume, and micro or mesopores distribution; (iii) identification of the compositions and processing routes that maximize CO₂ adsorption capacity and regeneration efficiency in bench-scale tests; and (iv) an evaluation of how additional chemical or thermal treatments influence textural properties, benchmarked against current literature. Overall, this study seeks to advance the development of optimized cellulose- and chitosan-derived carbon aerogels, reinforcing the role of porous solid materials as critical enablers of global decarbonization strategies.