Integrated Bench-Scale Parametric Study on CO₂ Capture Using a Carbonic Anhydrase Promoted K₂CO₃ Solvent with Low Temperature Vacuum Stripping

Abstract

A bench-scale unit was fabricated and used to investigate use of carbonic anhydrase (CA) promoted K 2 CO 3 solvent as an option for CO 2 capture from coal-fired power plants. Bench-scale parametric tests were performed at various CA concentrations, solvent flow rates, and reboiler duties. The CO 2 capture efficiency significantly increases, and regeneration energy requirement decreases, with increasing CA concentrations up to 2.5 g/L, with capture performance leveling off at higher enzyme doses (up to 4 g/L). Thus, at higher enzyme doses, the capture efficiency is equilibrium rather than kinetically controlled at the top of absorber, when using solvent regenerated via vacuum stripping at high (>35%) lean carbonate to bicarbonate (CTB) conversion levels, which limits the driving force for CO 2 absorption. The CO 2 capture efficiency also increases when reboiler duty was increased from 0.85 to 1.1 kW, although this also increases the regeneration energy penalty. In contrast, the effect of solvent flow rate on CO 2 capture efficiency is less pronounced. Further improvements to the CO 2 capture process using CA promoted K 2 CO 3 solvent with low temperature vacuum stripping could be potentially advanced by lowering vacuum pressure, improving strategies for increasing rich CTB conversion (e.g., advanced packing column and optimized L/G ratio), and decreasing absorption temperature.

Biocatalyzed Accelerated Post-combustion CO2 Capture and Stripping in Monoethanolamine

“…C, when 0.5 wt % CA@ fn -Zn/Fe/MS was added to 30 wt % MEA, desorption of the solvent was enhanced to ∼2.9 mM (taken as 100%), which is 2.6 times higher compared to neat 30% MEA. Similar studies were also reported by various researchers; for instance, Alvizo et al have reported the desorption of CA-assisted N -methyldiethanolamine (MDEA) (4.2 M) at 87–100 °C, and Qi et al found that CA-promoted K 2 CO 3 solution helps in stripping at 75–80 °C. It is well-known that the mechanism of the enzymatic reaction is very complex as a result of the involvement of multiple transition states.…”

“…Several research groups have used CA for CO 2 capture in basic solutions, such as 30% K 2 CO 3 and 5−10% alkanolamines. 54,55,49,10 The present study shows that the enzyme-supported matrix developed is robust because it could be recycled 15 times without loss in activity and detachment from the matrix. The CO 2 capture by gravimetric experiment (curve d in Figure 2A) and pressuredrop experiment (curve d in Figure 2B) results also confirmed that there is no significant reductive in activity, even after the 15th run.…”

Biocatalytic CO2 Absorption and Structural Studies of Carbonic Anhydrase under Industrially-Relevant Conditions

“…2019, 20, x FOR PEER REVIEW 11 of 13 designing an upscaled process, this enzyme must be kept in the absorption column, to operate at temperatures below its Tm. This can be achieved through protein immobilization in supports, which can then be used in different absorption process operations, including bubble columns [20] and stirred reactors [21,22]. After heating until 94 °C, the protein was analyzed again at 20 °C, and it is possible to observe that, at pH 9 and pH 11, the changes in the CD spectra caused by heating are maintained and, at pH 10, BCA seems to revert to a CD profile similar to the initial one (Figure S1).…”

“…This correlates to the changes in the secondary structure (Figure 2) where it is possible to observe that, under pH 9 and pH 11, the BCA structure changes more significantly due to the decrease in the antiparallel β-sheet In all cases, the T m values were found to be below typical temperatures adopted in large-scale stripping columns used in CO 2 absorption plants (>75 • C) [15], which indicates that, in the event of designing an upscaled process, this enzyme must be kept in the absorption column, to operate at temperatures below its T m . This can be achieved through protein immobilization in supports, which can then be used in different absorption process operations, including bubble columns [20] and stirred reactors [21,22].…”

Permeability and Stability of Hydrophobic Tubular Ceramic Membrane Contactor for CO2 Desorption from MEA Solution

“…To date, much fewer studies regarding membrane contactors have been conducted for membrane CO 2 desorption compared with membrane CO 2 absorption. Overall, one of the key obstacles that cause this situation is that CO 2 desorption is usually carried out at elevated temperatures, e.g., at 100-120 • C for elevated-pressure desorption or at 70-100 • C for vacuum desorption [7,8]. High temperature and chemical conditions require membrane materials to exhibit excellent characterizes.…”