A novel combining strategy of cellulose aerogel and hierarchically porous metal organic frameworks (HP-MOFs) to improve the CO2 absorption performance.

High CO₂ concentration in atmosphere causes serious environmental issues, and carbon capture and storage technologies have attracted attention as a means to reduce the atmospheric CO₂ concentration. Metal-organic frameworks (MOFs) can potentially be used for CO₂ adsorption, but their poor stability and microporosity limit their applications. Herein, a novel strategy was proposed to combine a cellulose aerogel and hierarchically-porous MOFs (HP-MOFs) with larger pores. According to this strategy, a series of microcrystalline cellulose/HP-UIO-66-NH₂ hybrid aerogels (MC-HUN-X) was constructed by adding a modulator (monocarboxylic acid, MA), followed by the in-situ growth of HP-UIO-66-NH₂ on a cellulose aerogel. By adjusting the chain length of MA, the structure–function relationship between pore size and the CO₂ adsorption capacity of MC-HUN-X was explored. The results showed that the CO₂ adsorption capacity increased first and then decreased upon increasing the MOFs pore size, while the adsorption selectivity of CO₂ continuously increased. Among all samples, MC-HUN-4 with a moderate pore size had the highest CO₂ adsorption capacity (1.90 mmol/g at 298 K and 1 bar) and adsorption selectivity (13.02 and 2.40 for CO₂/N₂ and CO₂/CH₄). The combination with a cellulose aerogel endowed MC-HUN-X with excellent mechanical stability and reusability. Cellulose/HP-UIO-66-NH₂ hybrid aerogel with larger aperture sizes of MOF showed excellent adsorption capacity and selectivity for CO₂, and the combination with aerogel could effectively improve the mechanical stability and reusability. [ABSTRACT FROM AUTHOR]