Structure-Activity Relationship of Carbonic Anhydrase Enzyme Immobilized on Various Silica-Based Mesoporous Molecular Sieves for CO₂ Absorption into a Potassium Carbonate Solution

In order to fulfill the application of carbonic anhydrase (CA) in the carbon dioxide capture process, immobilization technology will be used to enhance the stability of the enzyme. The structure of the support for the enzyme immobilization is important to determine the enzyme activity and stability. In this work, mesoporous molecular sieves with different dimensions and pore sizes were used as supports for the immobilization of CA. Characterization analysis indicated that the carrier material retained its integrity after enzyme immobilization. The half-life (t_1/2) of CA/KIT-6, CA/SBA-15, and CA/MCM-41 increased to 3.0, 2.8, and 2.0 times compared to the free CA enzyme. Additionally, the experimental results showed that when using SBA-15 with a two-dimensional structure and a large pore size as the carrier, the CA enzyme loading was high and retained 78% relative activity and 98% initial activity after 6 days at 40 °C. Comprehensively, CA/SBA-15 was more suitable for capturing CO₂ in flue gas than CA/MCM-41 and CA/KIT-6.