Enzymatic CO2 capture in countercurrent packed-bed column reactors with high performance random packings

Packed-bed columns with immobilized human carbonic anhydrase II (hCA II) enzyme on fourth generation random packings offer an attractive way to implement CO2 capture because of low pressure drop, high capacities and extremely large and uniform open area in every ring orientation. Enzyme-based CO2 removal performance of countercurrent packed-bed column reactors was analyzed by means of a dynamic 3D model which links the macroscopic volume-averaged continuity, momentum and species balance equations in the liquid and gas phases with simultaneous diffusion and chemical reaction at the enzyme washcoat/liquid film scale level. The results reveal that this low-cost, green, and environmentally friendly technology could be an interesting option to CO2 removal. The performance of packed-bed column reactors with immobilized hCA II enzyme on fourth generation random packings can be enhanced by diminishing the washcoat thickness, increasing the inlet buffer concentration and pK(a) constant and increasing the liquid velocity conserving a low pressure drop level. Also, operation with extra hCA II loadings allows to obtain higher CO2 conversion and avoids the deterioration of the CO2 hydration rate in long-term operation attributable to the decrease of hCA II enzyme activity.