Hierarchical porous MOF-199 mediated cellulosic paper for selective CO₂ capture

MOF-199 is considered to be an excellent CO₂ adsorbent owing to its substantial specific surface area, suitable pore structure and abundant sorption sites. However, powdered MOF-199 is prone to agglomeration and has poor recyclability. Herein, we proposed a MOF-199-based adsorbent by combining the MOF synthesis process with traditional papermaking process. Through such a design, MOF-199 particles are adhered on the surface of wood pulp fiber. The sufficient hydroxyl groups and electrostatic forces of cellulose facilitates the homogeneous and tight adhesion of MOF crystals. The optimal MP-4 sample demonstrated a high CO₂ adsorption capacity (1.80 mmol·g^--1 at 25 °C) and good CO₂/N₂ selectivity (30.06). Moreover, the composite sorbent can be easily regenerated. The adsorption mechanism was analyzed by the density functional theory approach. The simulation results showed that the carboxyl functional groups with a large number of oxygen atoms and active metal sites are the key to boost the CO₂ adsorption performance.