Scrubber Designs for Enzyme-Mediated Capture of CO2
Carbon dioxide is the most abundantly emitted greenhouse gas for which several technologies are being developed and intensively studied for capture and storage, except retrofit of amine scrubbers, none is proven at the commercial scale for treating post-combustion stack gases. Amine scrubbing, membrane separation, wet and dry mineral carbonation, pressure, temperature and electrical swing adsorptions, have been thoroughly reviewed in the 2005 survey by the Intergovernmental Panel on Climate Change (IPCC). However, an innovative approach that has escaped the attention of the recent IPCC concerns using biocatalysts for carbon dioxide hydration to bicarbonate. This review critically evaluates the recent patent literature regarding the different scrubber configurations in use for supporting carbonic anhydrase (CA), an ultrafast zinc-bearing metalloenzyme which catalyzes CO2 hydration to bicarbonate. It describes two membrane contactors using free soluble CA, the first one releasing gaseous CO2 and the second one being used to produce precipitated calcium carbonate (PCC). It also describes two contactors using immobilized CA, namely counter-current and cross-co-current packed columns, and two other contactors using either free or particle-immobilized CA. The review also deals with the use of a cohort of enzymes mimicking metabolic pathways to capture CO2 and potentially produce useful organic compounds.
Keywords: Carbon dioxide, capture, storage, recycling, enzymes, carbonic anhydrase, rubisco
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