Post-combustion CO2 membrane absorption promoted by mimic enzyme

Abstract

This work presents a CO2 membrane absorption process using a K2CO3 solvent promoted by a Zinc complex containing a cyclic ligand of 1,4,7,10-tetracyclodode cane (Zn-cyclen) in a membrane contactor. Zn-cyclen (referred as mimic enzyme in this work) resembles the natural enzyme carbonic anhydrase (CA), but is more stable, has a much longer life time and much smaller molecular weight (235g/mol) compared with CA. The mass transfer resistances in the membrane, gas and liquid phases in the membrane contactor were determined. The effects of gas film and liquid film resistances on the overall mass transfer coefficient were studied by varying the gas and liquid velocities. A tubular, hydrophobic porous glass membrane contactor with pore size of 200nm was used to study the CO2 absorption in potassium carbonate (0.5M K2CO3) solution promoted by different concentrations of mimic enzyme. The kinetic rate constant for absorption of CO2 in the K2CO3 solvent promoted by mimic enzyme was increased by 10 fold compared to the experiment without mimic enzyme. The significantly improved CO2 separation performance demonstrates a novel approach to the effective enhancement of CO2 absorption by using a low cost, chemically stable mimic enzyme.