CO2 adsorption using different COFs

https://doi.org/10.1039/D2MA00143H

“The adsorption of CO₂ in a COF depends on some factors, like the building blocks or framework of the COF, the type of linkages between the repeating units, and the porosity type. It has been observed that COFs having triarylamine in their structures are excellent CO₂ storage materials, and the adsorption efficiency increases with an increase in the triarylamine content. Donglin Jiang et al. recently reported four imine-linked COFs, TFPB–TAPB-COF, TFPA–TAPB-COF, BTMA–TAPA-COF, and TFPA–TAPA-COF, with similar hexagonal structures and almost the same porosity.¹⁷ They used tris(4-aminophenyl)amine and tris(4-formylphenyl)amine as triarylamine blocks and 1,3,5-tris(4-formylphenyl)benzene, 1,3,5-tris(4-aminophenyl)benzene, and 4,4′,4′′-boranetriyltris(2,3,5,6-tetramethylbenzaldehyde) as non-triarylamine building blocks. The CO₂ uptake capacities of the four types of COF are presented in Table 1. It was observed that TFPB–TAPB-COF acts as a very poor material for CO₂ adsorption due to the lack of triarylamine units. TFPA–TAPB-COF contains three triarylamine units in its framework, and it showed a 2.75-fold increase at 298 K and a 3-fold increase at 273 K in terms of the CO₂ adsorption capacity compared with TFPB–TAPB-COF, which does not have any triarylamine units. BTMA–TAPA-COF also contains the same number of triarylamine units (three), but due to the presence of boron in its framework it showed better CO₂ adsorption capacity. The maximum CO₂ adsorption capacity was shown by TFPA–TAPA-COF, which contains six triarylamine units in its framework, and it shows an almost 4.34-fold increase at 298 K and a 5.25-fold increase at 273 K in terms of CO₂ adsorption capabilities compared with TFPB–TAPB-COF, which does not contain any triarylamine units. Therefore, increasing the number of triarylamine units increases the CO₂ adsorption capabilities, and this type of COF can be used as an efficient catalyst for CO₂ fixation reactions.”