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

Abstract

Development of crystalline porous materials for selective CO2 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 m2 g-1) and a high CO2 adsorption capacity (3.58 mmol g-1) at room temperature (298 K). The CO2/CH4 and CO2/H2 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 CO2 binding affinity along with very high binding energy (-39.44 KJ mol-1) compared to other aromatic carbon-rich sites. Intrigued by the best CO2 adsorption capacity and high CO2 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.