Rationalizing the Efficiency of HKUST-1 for Capture and Biomimetic Sequestration of CO₂

In light of their outstanding properties, metal–organic frameworks appear to be the latest and most assured sorbent in CCUS technology. In this study, adsorption isotherms of pure CO₂, CH₄, and N₂ at three different temperatures were obtained for HKUST-1, and it showed a maximum CO₂ adsorption uptake of 8.25 mmol g⁻¹ at 298 K and 30 bar. HKUST-1 was also employed as support to immobilize carbonic anhydrase (CA) derived from the bovine erythrocytes through cross-linked enzyme aggregates. CO₂ hydration as well as its transformation into CaCO₃ was studied using the CA immobilized HKUST-1 (CA/HKUST-1). The biocatalytic activity, thermal stability, reusability, and storage stability of CA/HKUST-1 were evaluated through para-nitrophenyl acetate hydrolysis. CA immobilized on HKUST-1 exhibits a fairly low K_cat/K_m value than the free CA; regardless of the above, the reusability of CA/HKUST-1 for about 20 cycles makes it a suitable biocatalyst of CO₂ hydration under industrial operating conditions. The results demonstrated HKUST-1 as potential support for CA immobilization for CO₂ sequestration and high CO₂ uptake adsorbent.