Carbon dioxide capture by metal organic frameworks

Abstract

The design and synthesis of functionalized metal organic framework materials (MOFs) for reversible physisorption of CO₂ is discussed. This strategy of CO₂ adsorption in MOFs requires less energy for regeneration than materials relying on chemisorption. As a result the MOFs have received considerable attention as sorbent materials for strategic gases such as CO₂ and H2. In this review, we have discussed different MOFs and hybrid materials containing MOFs which can adsorb CO₂ at room temperature. In order to achieve high adsorption capacity, fast CO₂ adsorption-desorption and low energy requirement for regeneration are necessary. Several avenues for increasing the CO₂ adsorption capacity of such materials, for instance, introduction of open metal sites and the use of ligand molecules with specific functionalities (like -OH or -NH₂) have been described. It has been observed that CO₂ loading capacity of MOFs increases with functionalization. Herein, we have discussed how N-containing and fluorinated MOFs are designed to achieve higher CO₂ loading than their non-functionalized counterparts. Nanocarbons (e.g. carbon nanotubes, carbon nanofibres, etc.) are porous materials and a blend of these porous materials with porous MOFs or porous carbon derived from MOFs may act as a better adsorbate than even the pure materials. Enhancement of CO₂ loading by nanocarbon-MOF hybrid material is also discussed.