CO₂ Adsorption by Functionalized Nanoporous Materials: A Review

This review highlights the recent advances in the development of functionalized nanoporous adsorbents for CO₂ capture. Three main classes of materials are taken into account: zeolites, mesoporous silicates, and metal organic frameworks (MOFs). Proper modification of the cation content of zeolites, as well as the introduction of functional groups such as amine groups into ordered mesoporous silicates and MOFs, greatly enhance the CO₂ adsorptive properties of these substrates. Specifically, cation-exchanged zeolites can be currently considered the benchmark for ordered nanoporous CO₂ adsorbents, finding application also on a plant scale. Amino-functionalized mesoporous silicates tend to show a high affinity toward CO₂: while this could be an advantage when pushed purification is needed, it also implies that full regeneration of the adsorbent can be achieved only by putting its surface in contact with a completely CO₂-free environment. On the contrary, similarly modified MOFs show higher CO₂ adsorption working capacities: this potentially makes them even better candidates than their mesoporous inorganic homologues for a plant scale use. However, the persisting lack of reliable methods for the pelletization of both ordered mesoporous silicates and MOFs creates a care for further development efforts in the next future.