Carbon Capture Solvents Research Articles

Single-Pass Demonstration of Integrated Capture and Catalytic Conversion of CO2 from Simulated Flue Gas to Methanol in a Water-Lean Carbon Capture Solvent

Single-Pass Demonstration of Integrated Capture and Catalytic Conversion of CO₂ from Simulated Flue Gas to Methanol in a Water-Lean Carbon Capture Solvent

Functionalization of pyrolyzed hydrochar with nitrogen containing deep eutectic solvent for carbon capture at low and high pressure

The purpose of this research is to evaluate the effectiveness of pyrolyzed hydrochar functionalized with nitrogen containing deep eutectic solvent (DES) in the absorption of CO2 under low- and high-pressure conditions. Pyrolyzed hydrochars were synthesized by hydrothermally carbonizing pine at the temperature of 200°C and 260°C, followed by pyrolysis at 600°C. These pyrolyzed hydrochars were impregnated with 3 different nitrogen containing DES namely choline chloride: urea, choline chloride: glycerol, and tetrabutylammonium bromide: glycerol all in 1:2 molar ratio. It was found that the functionalized pyrolyzed hydrochars were enhanced with nitrogen and oxygen functionalities (N-H, C-N, and CO). The results also show a substantial reduction in surface area for the functionalized pyrolyzed hydrochars, ranging from 10.19 to 227.74 m2g−1, compared to the surface areas of pyrolyzed hydrochars of 306–337 m2g−1. On the other hand, an increase in N content up to 38 % was identified after functionalization of pyrolyzed hydrochars. Upon conducting CO2 uptake at low (0.1–1 bar) and high (2.5–3.5 bar) pressure, the functionalized pyrolyzed hydrochars exhibited an CO2 uptake of up to 9.5 mmol/g at high pressure, which was attributed to the increased total nitrogen content, enhanced surface functionalities, and available micropore volume. The low-pressure isotherm for functionalized pyrolyzed hydrochars showed Langmuir-type isotherm, suggesting a monolayer adsorption. In contrast, the high-pressure isotherms were better fitted to the Freundlich isotherm, suggesting a multilayer adsorption behavior. It was concluded that the enhanced CO2 uptake is the result of the combined impact of increased surface functionalities and porosity, which results in improved physical and chemical adsorption mechanisms at the high pressure.

Ionic liquid-ethanol mixed solvent design for the post-combustion carbon capture

Global warming driven by CO2 emissions is a critical global issue, with a significant portion of post-combustion emissions. Effective capture and recovery of CO2 from flue gas are essential for mitigating the greenhouse effect and advancing a low-carbon economy. This study proposes an ionic liquid (IL)-ethanol mixed solvent for post-combustion carbon capture. The [C1Py][CF3COO]-ethanol mixed solvent is tailored by solving a computer-aided ionic liquid design (CAILD)-based MINLP optimization problem. The performance of this mixed solvent was thoroughly evaluated through rigorous process simulations. Additionally, a standard oil-based measurement is introduced to assess the quality of energy consumption. The results indicate that the post-combustion carbon capture process using the [C1Py][CF3COO]-ethanol mixed solvent reduces carbon emissions, energy consumption, and total annual cost by 62.33%-75.51%, 64.71%-72.7%, and 53.6%-61.7%, respectively, compared to the MEA/MDEA processes. These findings suggest that the IL-ethanol mixed solvent process is a highly feasible and promising solution for environmental protection, energy efficiency, and economic viability in post-combustion carbon capture applications.

Molecular Understanding of Nitrogen Oxide Fixation of Water-Lean Carbon Capture Solvents by Atomistic Modeling

Molecular Understanding of Nitrogen Oxide Fixation of Water-Lean Carbon Capture Solvents by Atomistic Modeling

Low-temperature desorption in thermomorphic solvents for CO2 capture: Systems with N-methylcyclohexylamine and N,N-dimethylcyclohexylamine

The significant energy consumption associated with the carbon capture process has long posed a substantial obstacle to the extensive industrial utilization of amine solutions. Therefore, it is imperative to investigate a low-energy-consumption carbon capture solvent. This study meticulously examined thermomorphic absorbents composed of N-methylcyclohexylamine(MCA) and N,N-Dimethylcyclohexylamine(DMCA), delving into its absorption and desorption performances. Initially, focusing on absorption efficiency, we tested six varying concentration ratios of absorbents for CO2 absorption, scrutinizing their absorption rate and capacity. The analysis revealed that the rapid saturation of the absorbent stemmed from its limited absorption capacity. Notably, the MCA:DMCA=1 M:1 M ratio exhibited outstanding absorption capability, at 0.7015 mol CO2/mol amine, surpassing the absorption capacity of 30 wt% Monoethanolamine by a factor of 1.525. Subsequent desorption trials on MCA:DMCA=1 M:1 M at temperatures of 333 K, 348 K, and 363 K indicated successful desorption at 333 K, achieving an efficiency of 82.77 %, which rose with increasing temperature. Lastly, the estimated energy consumption for the latent heat and evaporation heat of this absorbent was approximately 0.342GJ/t CO2, marking a ∼61.1 % decrease compared to liquid-liquid phase change absorbents. These findings underscore the industrial promise of thermomorphic absorbents as a viable option for carbon capture applications.

Nanocellulose membrane with double-salt deep eutectic solvent for efficient carbon capture

Membrane-based gas separation technology is becoming increasingly attractive as a feasible alternative for carbon capture to alleviate global warming. Here, a double-salt deep eutectic solvent (DES) composed of organic salt (choline chloride) and inorganic salt (ZnCl2) is designed. The as-prepared DES exhibits a superb affinity and compatibility with nanocellulose because of the interactions between salt ions and cellulose carboxyl/hydroxyl groups. Through a solvent impregnation process, the DES was integrated into the nanocellulose gel precursor and used as a facilitated transport agent to form the functionalized nanocellulose membrane. The DES is tightly attached to the cellulose fibers with a high uniformity in the membrane matrix. Gas separation tests demonstrated that the DES@nanocellulose membranes presented a maximum CO2 permeability of 155.8 Barrer, with CO2/N2 and CO2/CH4 ideal selectivities of 43.6 and 48.4, respectively. Mixed gas separation tests were performed and the optimal membrane exhibited separation factors of 48.1 and 52.3 for CO2/N2 and CO2/CH4, respectively. The membranes provide a high solubility for CO2 due to the presence of abundant zinc ions, choline cations and carboxyl groups in the network, which can establish reversible coordination with CO2 and promote CO2 transport.

Experimental study on the performance of a highly efficient NE‐1 absorbent for CO2 capture

AbstractCO2 capture by absorption and stripping with aqueous amine is a well‐understood and widely used technology. However, drawbacks still exist in the practical applications, such as high energy consumption and easy degradation of the absorbents during the desorption process. In this paper, a novel NE‐1 absorbent was developed, and its suitable operating conditions were determined: concentration (45 wt.%), absorption temperature (40 °C), and desorption temperature (100 °C). The NE‐1 absorbent exhibits a high CO2 absorption capacity of 3.73 mol/kg, 1.33 times that of 30% monoethanolamine (MEA). After optimizing with carbamide as a corrosion inhibitor, 45% NE‐1a1 may attain an effective CO2 capacity of 2.5 mol/kg and over 70% desorption rate in five cycles, demonstrating excellent cycling stability performance. The research results have significant implications for developing an efficient and stable commercial carbon capture solvent and promoting the development of carbon reduction technologies. © 2024 Society of Chemical Industry and John Wiley & Sons, Ltd.

MANDREL: Modular Reinforcement Learning Pipelines for Material Discovery

AI-driven materials discovery is evolving rapidly with new approaches and pipelines for experimentation and design. However, the pipelines are often designed in isolation. We introduce a modular reinforcement learning framework for inter-operable experimentation and design of tailored, novel molecular species. The framework unifies reinforcement learning (RL) pipelines and allows the mixing and matching of choices for the underlying chemical action space, molecular representation, desired molecular properties, and RL algorithm. Our demo showcases the framework's capabilities applied to benchmark problems like quantitative estimate of drug-likeness and PLogP, as well as the design of novel small molecule solvents for carbon capture.

Integration of physical solution and ionic liquid toward efficient phase splitting for energy-saving CO2 capture

Carbon dioxide (CO2) capture from flue gas is crucial for achieving industrial carbon neutrality. Using a biphasic solvent can significantly reduce the volume of regenerated solvent for energy-saving carbon capture. In this study, a novel strategy for biphasic solvent preparation was proposed by combining amine blends (3,3′-Diaminodipropylamine, DADPA; N-Methyldiethanolamine, MDEA) and composite agents (1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, BN; sulfolane, TMS). The screened proportion of DADPA:MDEA:TMS:BN:H2O was 2:6:2:1:2 (labelled DMTB). Experimental evaluation revealed that the DMTB solvent exhibits a high CO2 capacity of 4.59 mol/L (in the 50 vol% rich phase), an efficient phase splitting rate (within 3 min) and a fast CO2 desorption rate. The dynamic phase-splitting capacity was evaluated by a quasi-two-dimensional separator, under various operational condition. The 13C NMR results indicated the formation of DADPACOO- in the CO2-saturated phase in the presence of water rather than bicarbonate while observing dissociative behaviour in MDEA and TMS. Therefore, the phase separation analysis revealed that the products of protonated amines and carbamic acid species were highly polar and preferred to dissolve in the water phase. This study provides an optional biphasic solvent with phase splitting ability for CO2 capture from flue gas.

HS3 as a novel solvent for carbon capture: Model validation and an industrial case study with comparison against 30 wt% MEA

CO2 capture is currently the most mature technological solution to reduce the environmental footprint of several emitters. However, the characterization of innovative blends with reduced energy demand and environmental impact is nowadays a challenge to increase the profitability and deployment of carbon capture on an industrial scale. This work investigates an innovative non-proprietary amine blend, called HS3. This article presents the development of a full model (including thermodynamics, kinetics, and mass transfer) and its validation with pilot-scale data covering temperature, CO2 concentration, and capture rate ranges of interest for industrial applications. The model predicts the main process Key Performance Indicators, such as CO2 captured, stripped flow, and cycling capacity, with deviations from the measurements lower than 7%. Then, the validated model is exploited for sizing and designing a carbon capture process from the flue gas generated within an oil refinery. A special focus is devoted to energy integration and process optimization by means of a sensitivity analysis. Eventually, HS3 performances are compared to benchmark MEA in terms of energy requirements and unit operation sizing for the same case study. Results show that HS3 can reduce the specific reboiler duty (MJ/kg CO2 captured) and the required solvent flow per unit of flue gas (kg/kg) by 21% and 19%, respectively. Examples of comprehensive models developed starting from lab-scale testing up to the validation on a pilot scale are still limited in the literature. The validation in a semi-industrial pilot is needed to fully understand the solvent properties including, for instance, drawbacks which cannot be detected on a small scale. Needless to mention, reliable models are needed for consistent scale-up, techno-economic assessment, and LCA analysis. Thus, this present presents a model validation using semi-industrial pilot data and measurements, which is not common in the literature.

Physicochemical and thermodynamic properties of binary amine-based deep eutectic solvents for carbon capture

Deep eutectic solvents (DESs) have attracted great interest as a new green alternative to ionic liquids. In order to investigate the potential of using DESs to replace traditional organic solvents in carbon capture processes, it is necessary to understand in detail the physicochemical and thermodynamic properties of DESs before and after CO2 absorption. In this paper, choline chloride was used as the hydrogen bond acceptor and ethanolamine as the hydrogen bond donor to prepare the original DES. Afterward, 5 % mass fraction of morpholine/sarcosine is then added to make two kinds of ternary secondary amine functionalized DESs. Six quaternary DESs were finally prepared by mixing 20 % solvent (water/glycerol/ethylene glycol) with the ternary DESs. Subsequently, the physicochemical properties of DESs, such as melting point, density, viscosity and surface tension, were experimentally determined over the temperature range of 303.15–353.15 K. The properties of ternary and quaternary DESs before and after CO2 absorption were especially predicted and analyzed using different models. It was found that the Vogel-Fulcher-Tamman model was more suitable for forecasting viscosity, and the Pelofsky equation was better for prediction of the relationship between surface tension and viscosity. Based on the experimental data and the solvent critical values predicted by the state equation, the thermodynamic properties of ternary and quaternary DESs before and after CO2 absorption, such as molar volume, isobaric expansion coefficient, lattice energy, activation energy, viscous flow entropy and enthalpy, were derived and analyzed.

Dynamic phase-splitting behaviour of biphasic solvent for carbon capture in a novel annular phase separator

Compared with biphasic solvents with blend amines, the mixture of physical solvent, amines and water (ternary solvent) was a promising preparation strategy. Chemical CO2 absorption with amine-based solvents is a promising route for industrial CO2 capture, but suffering from intensive heat duty for solvent regeneration. Developing high-performance biphasic solvent and efficient dynamic phase separator is an effective solution. In this study, poly(ethylene glycol) dimethyl ether (NHD) was selected as the separating agent to prepare a biphasic solvent based on a blended amine (Diethylenetriamine (DETA) and N,N-dimethylcyclohexylamine (DMCA) solvent with a screened proportion of DETA: DMCA: NHD: H2O of 1:3:4:2. The CO2 loading of the saturated solvent was 4.6 mol·L−1, with over 96% of the CO2 species concentrated in the rich phase, and with low viscosity of 48.60 mPa·s. The maximum desorption rate of CO2-saturated solvent was up to 1.68 mmol·min−1, and it increased by 243% compared to the MEA solvent (30 wt% MEA and 70 wt% water). The intermediates in various phases were identified using NMR to monitor the species changes during phase splitting. The dynamic phase-splitting capacity was first determined using a quasi-two-dimensional separator, and the results revealed that the liquid velocity of the mixed phase had a dominant effect on the separation efficiency. Furthermore, a novel annular phase separator was proposed to achieve efficient phase separation (the relatively rich separation efficiency increased by 13.40% compared to that with the benchmark.) by decreasing the tangential turbulence from the inlet velocity. The time–space distribution of the CO2 loading was obtained at different operational parameters. In particular, the effect of water content on separation efficiency was investigated to verify the adaptability of biphasic solvents for practical application.

Analysis and insights of the second-generation ternary AMP-PZ-MEA solvents for post-combustion carbon capture: Absorption-regeneration performance

This work comprehensively investigates absorption and regeneration performance of the second-generation AMP-PZ-MEA in comparison with the first-generation AMP-PZ-MEA, the benchmark 5 M MEA, and the conventional MEA at the same amine concentration. The performance indicators include CO2 absorption capacity, mass transfer coefficient, CO2 removal percentage, amount of desorbed CO2, initial CO2 desorption rate, and regeneration heat duty. Both 6 M (i.e., 2:2.5:1.5, 1.3:3.2:1.5, and 0.95:3.55:1.5) and 7 M (i.e., 2:2.5:2.5, 1.3:3.2:2.5, and 0.95:3.55:2.5) second-generation blends show more promising overall absorption and regeneration performance than 5 M, 6 M, and 7 M MEA. In comparison with the first-generation blend, 6 M and 7 M second-generation blends deliver more favorable mass transfer rate. Interestingly, an increase of PZ:AMP molar ratio accelerates mass transfer and absorption capacity but unfavorably affects solvent regeneration. Also, high viscosity of the second-generation 7 M blend (especially, at its equilibrium CO2 loading) retards the solvent regeneration. The key success for a formulation of AMP-PZ-MEA is appropriate PZ:AMP molar ratio and total amine concentration. Too high and too low PZ:AMP molar ratio lead to (i) solvent precipitation and (ii) imbalance of absorption and regeneration performance. Three standouts are recommended. 2.5:0.5:3 is attractive due to its low regeneration heat duty (42.1% lower than that of 5 M MEA). In terms of mass transfer coefficient, 0.95:3.55:1.5 shows 148.6% higher than 5 M MEA. 2:2.5:1.5 is also favorable according its high mass transfer coefficient (91.3% greater respecting 5 M MEA) and low regeneration heat duty (16.3% less than 5 M MEA).

Chemical space analysis and property prediction for carbon capture solvent molecules

A chemical space analysis of carbon capture amines and a computational screening framework for carbon capture solvents.

A Two-Dimensional Transport Model of Bipolar Membrane Electrodialysis for the Electro-Regeneration of Carbon Capture Solvents

Bipolar membrane electrodialysis (BPMED) is a promising technology that uses an electric field to split water into H+ and OH- ions. A repeating stack of cation selective, anion selective, and bipolar membranes are placed between two electrodes, creating a repeating pattern of acid, base, and diluting flow chambers. A major application of BPMED is the electrochemical solvent regeneration of capture solutions used in CO2 point source (PS) or direct air capture (DAC). Protons generated using BPMED can be used to shift the acid-base equilibria back to CO2, providing a more sustainable alternative to traditional thermal regeneration methods when integrated with renewable electricity sources. This method combines electrosynthesis and separation, producing a pure stream of CO2 for sequestration and a concentrated base stream.Despite its potential, current limitations to BPMED implementation for this application stem from a large power consumption and high membrane costs. In addition, gas bubbles in solution can cause high electrical resistances, and experimental studies of this phenomenon are challenging due to the small scale on which it occurs. To address these challenges, we present a two-dimensional model of BPMED for CO2 capture solvent recovery. This model depicts a single repeating cell triplet and was constructed using COMSOL Multiphysics version 6.1. The Navier-Stokes equations were implemented to compute a convection field, and the ionic species concentration was found by solving the Nernst-Planck equation. A source term in the concentration partial differential equations was implemented to account for ionic speciation and water splitting reactions, captured through kinetic rate expressions.Experimental validation was conducted on a PC Cell BED 1-4 recirculating batch system with a stack of seven cell pairs of PC acid 60 (anion selective), PC SK (cation selective), and PC Bip (bipolar) membranes. Good agreement between the model and experimental results across a range of conditions and variables demonstrates accuracy and robustness. The calculated pH and concentration profiles revealed that the majority of the speciation reaction takes place inside, or directly adjacent to, the bipolar membrane, including bubble nucleation. Bubbles form inside membrane pores and displace the electrolyte, greatly increasing the electrical resistance of the membrane, particularly when membrane porosity is low. However, the reaction plane location where bubbles are generated can be manipulated by increasing the channel width or reducing the applied voltage.Future research will focus on expanding to multiphase CFD simulations to investigate the effect on flow. Our two-dimensional model provides valuable insights into the complex and multifaceted nature of BPMED, offering a powerful tool for investigating small-scale processes and advancing the use of BPMED for CO2 capture solvent recovery. Figure 1

Design and simulate an amine-based CO2 capture process for a steam methane reforming hydrogen production plant

Steam methane reforming (SMR) is a common technique for hydrogen production, however CO2, which is created as a by-product, needs to be captured. Chemical absorption utilizing amine solvents is the most economically practical method of CO2 capturing. Amines are a class of organic compounds that are commonly used as chemical solvents for carbon capture. The effectiveness of a particular amine as a carbon capture solvent depends on its chemical structure and properties. Some commonly used amines for carbon capture include monoethanolamine (MEA), diethanolamine (DEA), and methyldiethanolamine (MDEA). This study aims to simulate SMR hydrogen production plant utilizing amine-based carbon dioxide capture system using Aspen HYSYS V11 software and figure out the efficiency of different chemical solvents in capturing carbon dioxide. The results of this study show that MEA has high efficiency to capture CO2 due to its high reactivity and ability to form a strong chemical bond with CO2. However, it is also highly corrosive and can be costly to regenerate.

Understanding the CO2 capture potential of tetrapropylammonium-based multifunctional deep eutectic solvent via molecular simulation

A multiscale theoretical study on the suitability of the bifunctional hydrophobic Deep Eutectic Solvent based on tetrapropylammonium chloride and acetic acid with ethanolamine is reported. Density Functional Theory quantum calculations along with classical Molecular Dynamics simulations provide a nanoscopic characterization of the properties of the studied sorbent in terms of intermolecular forces and liquid phase structuring and the characterization of the mechanism of CO2 absorption considering gas – liquid phase interfaces for neat CO2 and a realistic flue gas mixture. Results in this paper characterize the evolution of CO2 into liquid phases as well as the changes produced in the fluid upon gas capture through hydrogen bonding, void occupation and molecular clustering. The possible effect of having two different types of functionalities in the sorbent, amine and hydroxyl groups, which may lead to possible chemical and/or physical sorption is analyzed, considering their possible competing in CO2 capture. The reported study provides the first characterization of multifunctional Deep Eutectic Solvents for carbon capture from complex realistic gas mixtures.

Mechanistic insights to drive catalytic hydrogenation of formamide intermediates to methanol via deaminative hydrogenation

Amine-promoted hydrogenation of CO2 to methanol typically proceeds via a formamide intermediate when amines are used as additives or if the hydrogenation is performed in carbon capture solvents. The catalysts used for the hydrogenation of the formamide intermediate dictate the selectivity of the products formed: 1) Deoxygenative hydrogenation (C–O bond cleavage) resulting in N-methylation of amine and deactivation of the solvent, 2) Deaminative hydrogenation (C–N bond cleavage) resulting in formation of methanol and regeneration of the solvent. To date, catalytic reductions of CO2 with amine promoters suffer from poor selectively for methanol which we attribute to the limiting formamide intermediate, though to date, the conditions that favor C–N cleavage have yet to be fully understood. To better understand the reactivity of the formamide intermediates, a range of heterogenous catalysts were used to study the hydrogenation of formamide. Well-known gas phase CO2 hydrogenation catalysts catalyze the hydrogenation of formamide to N-methyl product via C–O bond cleavage. However, the selectivity can be readily shifted to selective C–N bond cleavage by addition of an additive with sufficient basicity for both homogenous and heterogeneous catalytic systems. The base additive shifts the selectivity by deprotonating a hemiaminal intermediate formed in situ during the formamide hydrogenation. This prevents dehydration process leading to N-methylated product, which is a key capture solvent deactivation pathway that hinders amine use in carbon capture, utilization, and storage (CCUS). The findings from this study provide a roadmap on how to improve the selectivity of known heterogenous catalysts, enabling catalytic reduction of captured CO2 to methanol.

Sustainability analysis of hydrogen production processes

Hydrogen is a versatile energy carrier and storage medium that is expected to have a key role in the energy transition, as it can be employed in a variety of applications. Hydrogen can be produced from different feedstocks and using different processes. Based on the production technology used, hydrogen is conventionally identified by a color. In this work, we compare different hydrogen generation processes: (i) green hydrogen, obtained by electrolysis of water using electricity from floating photovoltaic platforms, (ii) grid hydrogen, also obtained by electrolysis but using grid electricity, (iii) grey hydrogen, produced from natural gas using steam reforming and (iv) blue hydrogen, which is similar to grey hydrogen, but uses hot potassium carbonate as the solvent for carbon capture and storage. The paper considers the production of hydrogen necessary for 2 trips per day of a medium size ferryboat to navigate full electric for 7 h in the Adriatic Sea. Process simulation is applied to solve material and energy balances for each process investigated, as well as for the evaluation of capital and operating costs. Process simulation outcomes are then used to estimate three key performance indicators focused on energetic, economic, and environmental sustainability issues: the energy return on energy invested, the levelized cost of hydrogen, and the life cycle assessment. The energy indicator for grid and green hydrogen has a value of 13.39–14.29, versus a value of 4.59–5.48 for other hydrogen production methods from natural gas. The cost for green hydrogen is slightly higher (8.76) compared to the blue hydrogen (5.50) however green hydrogen has a much lower impact to the environment. Considering the combined results obtained by all the indicators, it is concluded that the most sustainable hydrogen production method is green hydrogen.

Novel nonaqueous solvent for carbon capture: Effects of glycol and water on CO2 absorption, desorption and energy penalty

Amidine-alcohol solution is an efficient absorbent for CO2 capture with high CO2 loading and low regeneration temperature compared with 30 wt% monoethanolamine (MEA) solution. However, the high viscosity restricts its further utilization in the industry. To decrease the viscosity of amidine-alcohol solutions during the absorption of CO2, different glycols including ethylene glycol, 1,3-propanediol, 1,2-propanediol, 1,3-butanediol and 1,4-butanediol were adopted in 1,5-diazabicyclo [4,3,0] non-5-ene (DBN)-glycol solutions for CO2 absorption. Both the absorption and desorption performances of those absorbents in the reaction with CO2 were investigated including the viscosity and regeneration energy. The CO2 loading can reach as high as 5.87 mol·kg−1 in DBN-1,3-propanediol solution, which is more than 3 times higher than that of 30 wt% MEA. Meanwhile, the viscosities for DBN-glycol-CO2 systems can be decreased more than 95% compared with 1,8-diazabicyclo [5,4,0] undec-7-ene (DBU)-glycerol-CO2 system. And DBN-ethylene glycol-CO2 system shows the lowest viscosity among the five glycols systems. With DBN-1,4-butanediol solution as an absorbent, the regeneration energy can be decreased as low as 1.38 GJ·ton−1 CO2, which is 62% lower than that of 30 wt% MEA. After 9 cycles of absorption–desorption process, the CO2 loading can be kept about 72% of the initial loading. Furthermore, the effect of water on absorption, desorption, viscosity and regeneration energy was also studied. It shows that the presence of water can increase the absorption rate and has little effect on the final CO2 loading while decreasing the desorption rate. Meanwhile, the presence of water increases the regeneration energy of DBN-ethylene glycol-H2O-CO2 system. However, considering the regeneration energy and viscosity, DBN-ethylene glycol solution is a promising solution for carbon capture and the regeneration energy can be decreased about 51 % even with 5 wt% water compared with 30 wt% MEA.