Stability of different MOFs for CO2 capture

https://doi.org/10.3390/en15093473

“The reusability of the adsorbent is an important factor for the practical application performance of the adsorbent; therefore, the cyclic adsorption performances were investigated. The amount of CO₂ adsorbed was calculated for each adsorption cycle and the results show that it decreases from 2.05 mmol/g to 1.92 mmol/g from the first to the sixth cycle. For CuBTC-BC-5, it decreases from 3.7 to 3.4 mmol/g, while an increase in adsorption from 3.7 to 3.9 mmol/g is observed for CuBTC-A-15. To test the stability of the results, experiments were performed with 20 cycle adsorptions, the results of which confirmed the previously observed trends (change does not exceed 3%). The increase in adsorption can be explained by the activation of new adsorption sites after the first ones are occupied. Comparing the results of cyclic CO₂ adsorption of CuBTC-BC-5 and CuBTC-A-15 with the adsorption results of these MOF-composite parent materials (Figure 12a,b), it can be concluded that the reusability of the obtained composites is affected by the synergistic effect of both CuBTC and composite parent materials because the adsorption capacity of biochar and aerosil remains almost stable (0.3% decrease for both montmorillonite and biochar) over a six-cycle interval.”

“Figure 12. CO₂ adsorption and desorption cycles of MOF-composites: (a) CuBTC and its composites containing aerosil (CuBTC-A-15), and biochar (CuBTC-BC-5); (b) montmorillonite and biochar; (c) UTSA-16 and montmorillonite containing UTSA-16-Mt-5; (d) UiO-66-BTEC and its composites containing montmorillonite (UiO-66-BTEC-Mt-15), and biochar (UiO-66-BTEC-BC-15).”

“The adsorption of CO₂ on UTSA-16 and its composites can be considered stable. Carbon dioxide adsorption and desorption cycles for UTSA-16 show adsorption reduction by 0.9% after five adsorption cycles (Figure 12c). Adsorption stability seems to slightly increase with UTSA-16 composite materials as their ability for CO₂ uptake after five cycles reduces by only around 0.4% (Figure S6b).