Process and biocatalyst development for CO2 capture and conversion assisted by carbonic anhydrase

Carbonic anhydrase (CA) has been proposed as an industrial biocatalyst since the middle of the 20th century. In the last 20 years, consolidated technologies for recombinant enzyme production and immobilization have provided new opportunities to apply biocatalysis of CA in carbon capture utilization and storage (CCUS) processes. Indeed, the conventional CO2 absorption process was reconsidered for post-combustion CO2 capture by replacing amine-based solvents with CA-supplemented alkaline solutions. Moreover, hybrid processes for CCUS assisted by CA have been proposed, demonstrating the high potential of the combination of CO2 enzymatic reactive absorption and biological/biocatalytic CO2 fixation pathways. The successful development of these processes is related to the design of effective CA-based biocatalysts. Several immobilization techniques have been applied to thermostable CAs for the design of biocatalysts for CCUS. This contribution highlights the collaborative and multidisciplinary research approach undertaken by the Italian National Research Council and the University of Napoli Federico II. Three successful immobilization techniques applied to recombinant CA forms are discussed: covalent attachment to fine granular solids, carrier-free immobilization methods, and in vivo immobilization techniques. Furthermore, we explore future perspectives on the integrated development of biocatalysts, bioreactors, and processes for CA-assisted CCUS.