Purification of Waste-Generated Biogas Mixtures Using Covalent Organic Framework’s High CO₂ Selectivity

Abstract

Development of crystalline porous materials for selective CO 2 adsorption and storage is in high demand to boost the carbon capture and storage (CCS) technology. In this regard, we have developed a β-keto enamine-based covalent organic framework (VM-COF) via the Schiff base polycondensation technique. The as-synthesized VM-COF exhibited excellent thermal and chemical stability along with a very high surface area (1258 m 2 g −1 ) and a high CO 2 adsorption capacity (3.58 mmol g −1 ) at room temperature (298 K). The CO 2 /CH 4 and CO 2 /H 2 selectivities by the IAST method were calculated to be 10.9 and 881.7, respectively, which were further experimentally supported by breakthrough analysis. Moreover, theoretical investigations revealed that the carbonyl-rich sites in a polymeric backbone have higher CO 2 binding affinity along with very high binding energy (−39.44 KJ mol −1 ) compared to other aromatic carbonrich sites. Intrigued by the best CO 2 adsorption capacity and high CO 2 selectivity, we have utilized the VM-COF for biogas purification produced by the biofermentation of municipal waste. Compared with the commercially available activated carbon, VM-COF exhibited much better purification ability. This opens up a new opportunity for the creation of functionalized nanoporous materials for the large-scale purification of waste-generated biogases to address the challenges associated with energy and the environment.

Synthesis and Applications of Cage-Based Covalent Organic Frameworks

“…COF frameworks derived from cage molecules can be customized to exhibit specific pore sizes and functionalities. This tunability enables precise control over molecular recognition, drug delivery, and separation processes, making them ideal candidates for water purification and catalysis applications. , The covalent bonds in COF structures offer enhanced stability and robustness compared to the noncovalent interactions in cage compounds. This increased stability may pave the way for the development of cage-based COFs with improved thermal, chemical, and mechanical properties, thereby expanding their utility in catalytic processes.…”