Recent advances and perspectives in CO2 capture by enzymatic reactive absorption

Enzymatic reactive absorption has been investigated in the last decade as novel strategy to develop environmental friendly technology for post-combustion CO2 capture [1, 2]. The process is based on CO2 absorption in aqueous solutions, the absorption rate is enhanced by the catalytic action of the enzyme carbonic anhydrase (E.C. 4.2.1.1). At temperature lower than 40°C, CO2 hydration reaction is the slowest reaction (10-2 s-1) among those occurring during CO2 reactive absorption in conventional alkaline and amine solvents: hydroxylation rate at pH 10 ranges between 10-1 and 1 s-1 and carbamate formation rate at 3M MEA is about 103 s-1. Carbonic anhydrase is the ubiquitous enzyme devoted to CO2 hydration catalysis in Nature. Depending on enzyme form, about 10-5 M carbonic anhydrase are able to speed up CO2 hydration to bicarbonate so that first order rate constant results between 1 and 103 s-1 [1]. The present contribution reports survey of recent results on the development of CO2 capture processes based on enzymatic reactive absorption from lab to pilot scale. Main investigated issues were: kinetics of thermostable carbonic anhydrase [4], development of solid biocatalyst for industrial application through carbonic anhydrase immobilization [3], proposed reactor configurations for CO2 enzymatic reactive absorption [1, 2], theoretical models CO2 enzymatic reactive absorption unit [5].