Development of a Potassium Carbonate-based Absorption Process with Crystallization-enabled High-pressure Stripping for CO2 Capture: Vapor–liquid Equilibrium Behavior and CO2 Stripping Performance of Carbonate/Bicarbonate Aqueous Systems

Abstract

A novel absorption-based post-combustion CO 2 capture process is being developed to reduce the energy use associated with CO 2 stripping and compression. The process features the use of a concentrated potassium carbonate/bicarbonate (PCB) aqueous solution as a solvent and high-pressure CO 2 stripping with a bicarbonate-dominant slurry enabled by crystallization of the CO 2 -rich solution. Vapor-liquid equilibrium data under the typical stripping conditions of the process were measured and CO 2 stripping tests were performed under various pressures, temperatures, PCB concentrations, and CO 2 loading levels using a bench packed-bed stripping column. The results showed that CO 2 stripping with a highly concentrated, highly CO 2 -loaded PCB solution/slurry at a high temperature was favored to attain a high stripping pressure and a low water vapor-to-CO 2 pressure ratio in the product gas stream. The total heat use measured for CO 2 stripping with the PCB system was up to three times lower than that of the benchmark 5 M monoethanolamine system under favorable conditions.

Is Hydroxide Just Hydroxide? Unidentical CO2 Hydration Conditions during Hydrogen Evolution and Carbon Dioxide Reduction in Zero-Gap Gas Diffusion Electrode Reactors

“… This so-called “hydroxide path” dominates at CO 2 hydration at pH > 8.5 (Figure ). 50, At low current densities ( j = 0–100 mA cm –2 ), the number of OH – is limited by the membrane’s ion exchange capacity and the high CO 2 availability results in HCO 3 – formation via eqs and and CO 2 + CO 3 2– + H 2 O ↔ 2HCO 3 – . The bicarbonate-dominated near-neutral cathode/membrane surface was verified by operando Raman spectroscopy at 0 mA cm –2 .…”

“…. 52 The bicarbonate-dominated near-neutral cathode/membrane surface was verified by operando Raman spectroscopy at 0 mA cm −2 . 9 During high current electrolysis (>100 mA cm −2 ), the hydroxide ions formed in eq 4 generate carbonate ions and increase the local pH > 12, favoring the hydroxide path of CO 2 hydration.…”

Phase Splitting Agent Regulated Biphasic Solvent for Efficient CO2 Capture with a Low Heat Duty

“…The heat duty ( Q regen ) is calculated by the following method using the method reported in the literature , where m am is the molar amount of the amine used per one ton CO 2 captured, kmol; m W is the molar amount of water vapor generated per one ton CO 2 produced, kmol; α repents CO 2 loading, kmol kmol –1 ; Δ h rxn (α) is reaction enthalpy at different loading, kJ kmol –1 ; r p and r W are the ratios in molarity between phase splitting agents or water and amines in fresh solution; c am , c W , c p and c CO 2 are the heat capacity of amines, water, phase splitting agent, and CO 2 , kJ kmol –1 K –1 ; and λ represents the water latent heat, kJ kmol –1 . The heat capacity of the solvent is assumed to be equal to that of water.…”

CO2 Removal via an Environmental Green Solvent, K2CO3–Glycine (PCGLY): Investigative Analysis of a Dynamic and Control Study

“…Hence, the scale-up that includes a complete recycle is designed and validated with the actual steady-state result. In the Aspen Plus simulator, the absorber column is simulated using the Radfrac type of column, 35 − 37 and the process is conducted under the equilibrium approach. This method offers two types of efficiencies as tuning factors to improve the prediction of the column composition, which are the Murphree efficiency and vapor efficiency.…”