Hierarchical Stable Enzyme Microenvironments for High-Temperature Stability in Amine Solvents



Several methods have been proposed for capturing the CO2 emitted into the atmosphere by human activity. To date, mainly amine-based absorption processes are currently among the more promising systems for post-combustion CO2 capture. Tertiary amine solvents obviate the need for a high solvent regeneration temperature and fast absorption can be achieved with the use of carbonic anhydrase (CA), as an activator. In this study, the capacity of CA immobilization on nanoporous microparticles hierarchically structured to enhance their stability in tertiary amines is investigated. These microstructures allow for an efficient supply and presentation of substrate in the non-aqueous solvent to the enzyme catalytic center and the particles' large size is attractive to make separation and reuse facile. These hierarchically structured particles conserve 70% of their initial activity after 30 d at 50 °C in amine solvent, whereas the free enzyme shows no activity after 1 h in the same conditions. In this work, we have overcome the technical hurdle linked to the recovery of the biocatalyst after operation thereby reducing costs of the system and importantly these micro-bioparticles have shown a remarkable increase of the thermal stability of CA in an amine-based CO2 sequestration solvent as determined by a para-nitrophenyl acetate assay.