Modelling of Enzymatic Reactive CO₂ Absorption

Abstract

Post-combustion CO2 capture strategy asks for novel effective processes avoiding the use of polluting solvents and oriented towards CO2 utilization. Recent research efforts are focused on the development of CO2 absorption processes promoted by the activity of the enzyme carbonic anhydrase (EC - 4.2.1.1) (Leimbrik et al., 2017; Russo et al., 2013). This ubiquitous enzyme is able to catalyse the CO2 hydration reaction and can be used to enhance CO2 absorption rate into aqueous alkaline solvents such as carbonate solutions. The adoption of the biomimetic strategy for post-combustion CO2 capture is based on the use of environmental friendly solvents. Recent studies on the development of carbonic anhydrase biocatalysts for CO2 capture through enzymatic reactive absorption focused on different enzyme immobilization techniques. Moreover, theoretical studies showed the potential use of immobilized enzymes in typical gas-liquid contactors. The present contribution concerns the rational design of absorption columns through the use of kinetic parameters assessed for carbonic anhydrase immobilized on fine particles. The kinetics of CA immobilized on magnetic nanoparticles have been previously characterized under conditions relevant for the industrial application (K2CO3 solutions at 25-40°C and at different carbonate conversion degrees) (Peirce et al., 2017; Peirce, 2017). The model simulations provided information on the performances of the technical grade CA and of the biocatalyst made with nanoparticles (NPs) coated with covalently immobilized CA. The results showed that effective intensification of the capture process can be achieved using the fine slurry biocatalyst.