Kinetic Assessment of Thermostable Carbonic Anhydrase for CO2 Capture Processes

The most recent challenge to reduce greenhouse gas emissions is the development of Carbon Capture and Sequestration (CCS) processes for CO2 removal from flue gases. The biomimetic strategy is based on the adoption of Carbonic Anhydrase (CA) as an industrial biocatalyst as an alternative to conventional additives (e.g. amines) to increase CO2 absorption rate in aq. solutions. The present contribution concerns the kinetic assessment of a recombinant CA (SspCA) identified and characterized in the thermophile bacterium Sulfurihydrogenibium sp YO3AOP1. The CA characterization - long term stability included - was carried out under operating conditions close to those typically adopted in CCS plants. The absorption rate of pure CO2 into aq. solutions was assessed by working out time-resolved measurements of gas pressure decay in a batch stirred reactor. The first order enzyme kinetics for SspCA was assessed at 25 °C in buffer at pH 9.6. Long term stability of SspCA at 40 and 70 °C was promising compared with that of CA from bovine erythrocytes.