Kinetic performance of CO2 absorption into a potassium carbonate solution promoted with the enzyme carbonic anhydrase: Comparison with a monoethanolamine solution

Abstract

h i g h l i g h t sThe CA enzyme activity did not change noticeably with CO 2 loading in a PC solution. Absorption rate into CO 2 -rich PC with 3 g/L of CA were twice that into a rich 5 M MEA. Liquid-phase mass transfer resistance dominated in both the PC and MEA systems. Packing volume of IVCAP absorber with 10 g/L of CA was comparable with that of MEA. a b s t r a c t Development of enzyme-mediated solvents are regarded as a potential option to overcome the energy use disadvantages associated with the benchmark monoethanolamine (MEA) solvent for post-combustion CO 2 capture. In this work, the kinetics of CO 2 absorption into a 20 wt% potassium carbonate (PC) solution promoted with the enzyme carbonic anhydrase (CA) was investigated using a stirred tank reactor. Experimental results showed no noticeable change in the intrinsic activity of the CA enzyme with increasing CO 2 loading in PC solution. A rate-based mass transfer analysis was conducted using the enzymatic kinetics measured, and results revealed that in a packed-bed column, the CO 2 absorption rates into a lean and rich PC solution with 3 g L À1 CA were 50% lower and 2.2 times higher, respectively, than those into their 5 M MEA counterparts. The liquid-phase mass transfer resistance was dominant for both PC-and MEA-based systems. Modeling results revealed the effective packing volume of the absorber with PC in the presence of 10 g L À1 CA was only slightly larger than that with MEA for post-combustion CO 2 capture.

Characterization of technical grade carbonic anhydrase as biocatalyst for CO2 capture in potassium carbonate solutions

“…The observed decrease of the k E with the solvent loading is in agreement with Hu et al . even though Zhang and Lu pointed out a negligible effect.…”

“…Two groups of tests were carried out: the first group was carried out at enzyme concentration set at 0.3 and 0.6 kg m −3 , the second group was carried out at enzyme concentration set less than 0.018 kg m −3 . The first group of tests at large NovoCA concentrations (0.3 and 0.6 kg m −3 ) was aimed to be representative for the development of CO 2 capture processes by means of reactive absorption . The second group of tests was aimed to the assessment of kinetic parameters for enzyme catalyzed CO 2 conversion according to the theory described in the Materials and methods section.…”

“…The first group of tests at large NovoCA concentrations (0.3 and 0.6 kg m −3 ) was aimed to be representative for the development of CO 2 capture processes by means of reactive absorption. 4,7,15,20 The second group of tests was aimed to the assessment of kinetic parameters for enzyme catalyzed CO 2 conversion according to the theory described in the Materials and methods section.…”

“…As a matter of fact, the development of effective enzyme immobilization techniques – i.e., that allow an increase of CA stability and reuse of the biocatalyst – seems currently the most reliable strategy to establish a CO 2 capture process by enzymatic reactive absorption . From an economic point of view, the industrial development of such a biocatalyst can take advantages by using technical grade CA instead of pure CA ,.…”

Reactive absorption of CO2 into enzyme accelerated solvents: From laboratory to pilot scale

“…Furthermore, there has been some investigation of reaction kinetics of enzyme accelerated CO 2 reactions in stirred cell, closed reactors mostly performed with high CO 2 partial pressures or in membrane contactors [13,[15][16][17][18][19][20]. These investigations have revealed increased CO 2 absorption rates by the addition of enzyme to most capture solvents.…”