MEA Solution Research Articles

Loosely bonded dual-functionalized ionic liquid-based phase change solvent for energy-saving CO2 capture

A phase change solvent based on a novel loosely bonded dual-functionalized ionic liquids (ILs) containing diethylenetriamine (DETA) and 1-methylimidazole (1-MI), namely [DETA][1-MI], was developed. The strong anion–cation interactions in an ILs inhibited the CO2–ILs interaction and decrease the absorption capacity of the ILs. The weak interaction of [DETA][1-MI] retained most of the absorption capacity of DETA and 1-MI (up to 2.06 mol CO2/mol ILs). When simulated flue gas was fed into the [DETA][1-MI] + dimethylformamide (DMF) + H2O phase change solvent, the CO2-rich phase had a CO2 concentration of up to 6.51 mol CO2/L and a volume ratio of 42.2%. Moreover, a regeneration efficiency of > 90% was maintained even after three regeneration cycles at 393 K. The corresponding regeneration heat (1.40 GJ/ton CO2) was only 36.8% of 30 wt% monoethanolamine (MEA, 3.80 GJ/ton CO2). To the best of our knowledge, it’s well below the reported regeneration energy of amine-based absorbents. In addition, the corrosion rates of the rich and lean phases were only 0.58% and 0.51% of those of the saturated MEA solution, indicating that the corrosivity of [DETA][1-MI] + DMF + H2O was negligible. Moreover, [1-MI]− was observed to promote the formation of m-DETACOO− and HCO3−/CO32−, further enhancing the CO2 absorption capacity. Therefore, the proposed [DETA][1-MI] + DMF + H2O was verified to be a promising absorbent with favorable absorption properties, a low corrosion rate, high cyclic stability, and superior energy efficiency for CO2 capture.

Optimization of carbon dioxide absorption in a continuous bubble column reactor using response surface methodology

AbstractCarbon dioxide absorption using amine based solvents is a well‐known approach for carbon dioxide removal. Especially with the increasing concerns about greenhouse gas emissions, there is a need for an optimization approach capable of multifactor calibration and prediction of interactions. Since conventional methods based on empirical relations are not efficiently applicable, this study investigates use of Response Surface Methodology as a strong optimization tool. A bubble column reactor was used and the effect of solvent concentration (10.0, 20.0 and 30.0 vol%), flow rate (4.0, 5.0 and 6.0 L min−1), diffuser pore size (0.5, 1.0 and 1.5 mm) and temperature (20.0, 25.0 and 30.0°C) on the absorption capacity and also overall mass transfer coefficient was evaluated. The optimization results for maintaining maximum capacity and overall mass transfer coefficient revealed that different optimization targets led to different tuned operational factors. Overall mass transfer coefficient decreased to 34.7 min−1 when the maximum capacity was the desired target. High reaction rate along with the highest absorption capacity was set as desirable two factor target in this application. As a result, a third scenario was designed to maximize both mass transfer coefficient and absorption capacity simultaneously. The optimized condition was achieved when a gas flow rate of 5.9 L min−1, MEA solution of 29.6 vol%, diffuser pore size of 0.5 mm and temperature of 20.6°C was adjusted. At this condition, mass transfer coefficient reached a maximum of 38.4 min−1, with a forecasted achievable absorption capacity of 120.5 g CO2 per kg MEA.

Thermodynamic analysis of a post-combustion carbon dioxide capture process in a pilot plant equipped with a heat integrated stripper

This paper presents a thermodynamic analysis of a carbon dioxide absorption process from flue gases, focusing on the Heat Integrated Stripper (HIS) as a promising modification to the conventional process. The primary objective is to compare the performance of the HIS-modified process with that of the standard process. Experimental research was conducted on a mobile pilot plant using aqueous solutions of MEA 30% for treating 200 m3/h of the flue gas.An advanced data validation and reconciliation method was used to reconcile measurements in the mass balancing of the carbon dioxide absorption process. The results demonstrate that heat integration has a positive impact on the temperature profile of the stripper, leading to an increase in carbon dioxide capture without requiring additional heat consumption. Specifically, the reboiler heat duty in the process was reduced from 3.22 to 3.00 MJ/kgCO2, indicating the effectiveness of the HIS-modified process in reducing energy consumption. The use of the advanced data validation and reconciliation method also increases the reliability of the obtained results, which can be beneficial for process modeling and design. These findings contribute to the development of more efficient carbon capture technologies.

Evaluation of phase separation behavior of amine + organic solvent + H2O phase change absorbents

CO2 phase change absorbents, CPCAs, have attracted growing interest due to their potential of energy saving for CO2 capture. Unclear phase separation pattern is challenging for the efficient development of CPCAs. The effect of organic solvents properties on the phase separation process was investigated in this work. The difference of ion–dipole interaction between ion-organic solvent and ion-water was used to illustrate the phase separation behavior. Relative dielectric constant and ET(30) to water were proposed as indicators to provide guidance on the selection of organic solvents in CPCA. The organic solvents with less dielectric constant and ET(30) relative to water, were tend to phase split, and higher ion distribution coefficient obtained. The developed MEA CPCAs showed larger CO2 cyclic capacity than 30wt.%MEA, among which 1,4-dioxane CPCA was 49.0% higher than benchmark MEA solution.

Monoethanolamine (MEA) Degradation: Influence on the Electrodialysis Treatment of MEA-Absorbent.

The thermal-oxidative degradation of aqueous solutions of carbonized monoethanolamine (MEA, 30% wt., 0.25 mol MEA/mol CO2) was studied for 336 h at 120 °C. Based on the change in the color of the solution and the formation of a precipitate, the occurrence of thermal-oxidative degradation of the MEA solution with the formation of destruction products, including insoluble ones, was confirmed. The electrokinetic activity of the resulting degradation products, including insoluble ones, was studied during the electrodialysis purification of an aged MEA solution. To understand the influence of degradation products on the ion-exchange membrane properties, a package of samples of MK-40 and MA-41 ion-exchange membranes was exposed to a degraded MEA solution for 6 months. A comparison of the efficiency of the electrodialysis treatment of a model absorption solution of MEA before and after long-time contact with degraded MEA showed that the depth of desalination was reduced by 34%, while the magnitude of the current in the ED apparatus was reduced by 25%. For the first time, the regeneration of ion-exchange membranes from MEA degradation products was carried out, which made it possible to restore the depth of desalting in the ED process by 90%.

Performance of CO2 capture technology based on gas cyclone-liquid jet absorption

Growing CO2 emissions from the chemical industry are causing a range of environmental problems, and there is an urgent need for innovation in carbon capture technology. In this paper, the effect of the gas cyclone–liquid jet separator for absorbing CO2 gas is studied. Using MDEA, MEA, DEA, AMP, PZ, and other solutions and their mixtures as absorbents, the absorption performance of absorbents for CO2 gas was studied. The influence of various process parameters on the absorption efficiency of CO2 gas was mainly investigated, and the effect and feasibility of CO2 absorption by the gas cyclone–liquid jet separator were studied. The experimental results show that adding a suitable activator to the MDEA solution is beneficial to improve the absorption effect of CO2, and the absorption efficiency can reach more than 97%. The absorption efficiency of 3.3mol·L−1 MEA solution can reach 97.99%, which can meet various carbon emission requirements. The research provides technical guidance for absorbing carbon dioxide to achieve carbon neutrality.

CO2 capture based on Al2O3 ceramic membrane with hydrophobic modification

In this paper, Al2O3 ceramic membrane is modified to hydrophobicity by grafting 1 H,1 H,2 H,2 H-perfluorodecyltriethoxysilane. And its properties are characterized in detail. CO2 capture performance of ceramic membrane is investigated by experiments. Results show that wetting resistance after modification is significantly improved, and contact angle increases from the initial 49.8–130.9°. However, hydrophobic modification has no significant effect on the crystalline phase, surface morphology and pore size distribution of the ceramic membrane. With ethanolamine (MEA) as absorbent, CO2 mass transfer rate and capture efficiency using modified hydrophobic ceramic membrane are 46.6 × 10−3 mol/(m2·s) and 98.0%, showing significantly increase compared to the original membrane. After 72 h immersion in MEA solution, quality of ceramic membrane does not change significantly. And there is almost no change in average pore size. We believe this study will provide a reference for the industrial application for CO2 capture by gas-liquid membrane contactor with ceramic membrane.

Carbon Capture From Coal Power Plants And Algae Farming With Technical-Economic Analysis

CO2 is a major cause of global warming, one of the world's most critical environmental problems and responsible for about 55% of global warming. According to research, the quantity of CO2 in the atmosphere corresponds well with the growth in the average global temperature of the planet's surface. The main aim of this work is to investigate different emerging Technologies for the carbon capture from power plants and its atmosphere. After capturing of CO2, it is used for the injecting in raceway ponds for micro algae cultivation. Mathematical and experimental analysis for the carbon capture and Sequestration from the coal power plant have been performed in the RKDF University and proposed the microalgae production using captured CO2. For that total 24 experiments were performed to get the efficiency of the CCS plant. The result shows that Input of 250 kg/ hr of flue gasses has been used to capture the CO2. Sodium Carbonate solution of 10% will be sprinkled on top of the packing in tower-A to increase the contact area. The gases are now subject to the counter-current of MEA solution of 30% contained with 1 kg of CO2. MEA - CO2 mixture is heated up to 155°C with the help of a Scheffler dish collector. CO2 gas released from the MEA - CO2 mixture when heated above 130°, the maximum efficiency of the CCS plant of 87.58 % on 04 Jan 2021 at 1200 Noon.

Laboratory methods for the analysis of key indicators of the purity of amino solutions

At present, for the purification of gases from sulfur compounds, amine solutions are mainly used, which become contaminated during operation, which entails a number of technological problems. We have chosen a list of key indicators characterizing the degree of contamination of solutions, which consists of the concentration of thermostable salts, the mass fraction of chlorine ions, the mass fraction of iron and nickel, and foaming solutions. The article presents a multiple description and essence of methods for determining the indicators of the degree of contamination of solutions. For testing, 10 regenerated MDEA and MEA solutions were selected. For each value obtained, the limit of the total error and the allowable interval of the value were calculated to determine the convergence and adequacy of the measurements. All values fall within the allowable interval, taking into account the characteristic error of MI, which indicates the reliability and expediency of using these methods. Keywords: methylethanolamine; methyldiethanolamine; thermostable salts; corrosion; electrical conductivity; foaming; cleaning; activated carbon; ion-exchange resin.

CFD modeling of MEA-based CO2 spray scrubbing with computational-effective interphase mass transfer description

Great concerns for global warming and stringent regulations have spurred the development of feasible technologies to reduce CO2 emissions from the power generation sector. In thermal power plants, spray scrubbing is one of the most used methods for separating gaseous pollutants, which inspires the idea of applying spray scrubbing in CO2 capture. However, this new idea still necessitates investigation, particularly in developing a novel modeling tool. This motivates us to present the CFD modeling of CO2 spray scrubbing using MEA solution in this work. CO2 spray scrubbing is a complex process. Herein, the established model combines the multiphase flow with interphase transfer and chemical reactions in the Euler-Lagrange framework. To efficiently describe the interphase mass transfer, we proposed a new method based on the thermodynamic consistency between the CO2 equilibrium pressure and the enthalpy of CO2 absorption. Validated by the experimental data, this method can achieve an acceptable balance between accuracy and computational cost. The zwitterion mechanism was employed to describe the chemical reactions. Kinetic analysis shows that E = (1 +Ha2)0.5 can reasonably evaluate the enhancement factor value in a wide range of MEA concentrations. Additionally, the effects of operating parameters on CO2 removal were numerically studied, focusing on mass transfer characteristics. Therefore, the proposed numerical model will be beneficial for facilitating the deployment of CO2 spray scrubbing in the power sector, and the numerical results provide helpful information for design and optimization.

CFD modeling on the chemical absorption of CO2 in a microporous tube-in-tube microchannel reactor

In this paper, combining recently developed mesoscale mass transfer model with reaction kinetics, the chemical absorption process of CO2 by MEA solution in a microporous tube-in-tube microchannel reactor (MTMCR) was numerically simulated for the first time. The predicted values by CFD simulations were in agreement with the public experimental data (Na-Na Gao et al., Ind. Eng. Chem. Res., 2011). The distributions of CO2 removal efficiency and volumetric mass transfer coefficient under different gas flow rate, solvent flow rate, solvent temperature, and MEA concentration were analyzed. Among these factors, MEA concentration had a more significant influence on the CO2 chemical absorption. The KGa in the MTMCR was more than 200 times of that in the randomly packed bed under the similar operating conditions. The local mass transfer rate of chemical absorption was one order of magnitude higher than that of physical absorption. This research work could lay a theoretical foundation for the simulation of the complex gas–liquid systems including the chemical absorption by CFD method.

Energy-efficient carbon dioxide capture using a novel low-viscous secondary amine-based nonaqueous biphasic solvent: Performance, mechanism, and thermodynamics

Biphasic solvents have been widely studied for CO2 capture due to their remarkable energy-saving potentiality. However, most existing biphasic solvents suffer from the high viscosity of their CO2-rich phase. This study proposed a novel low-viscous secondary amine-based nonaqueous biphasic solvent for CO2 capture. With dimethyl sulfoxide (DMSO) as the organic diluent and pentamethyldiethylenetriamine (PMDETA) as the phase splitting agent, the secondary amine of 2-methyl-ethynolamine (MAE) was proved to be the optimal candidate for preparing the biphasic solvent. The MAE/DMSO/PMDETA (M/D/P) biphasic solvent could realize a high CO2 loading of 0.84 mol mol−1 and the viscosity of its CO2-rich phase was only 8.87 mPa s, which was significantly lower than that of most reported biphasic solvents. The reaction mechanism analysis revealed that M/D/P absorbed CO2 to form products of protonated amines, carbamate, and carbamic acid species. Since the products were polar and showed a stronger affinity to polar DMSO, while less polar PMDETA was isolated, thereby resulting in a phase change. Thermodynamics analysis showed that the M/D/P biphasic solvent could sharply cut down the sensible heat and latent heat during CO2 desorption. Eventually, the total regeneration energy penalty of M/D/P was significantly reduced by 46.3% compared with the benchmark aqueous MEA solution.

Detection of Viable Zygosaccharomyces rouxii in Honey and Honey Products via PMAXX-qPCR

In order to establish a fast detection method for the living Zygosaccharomyces rouxii (Z. rouxii) cells in honey and honey products, the performance of propidium monoazide bromide (PMA) and enhanced propidium monoazide bromide (PMAXX) combined with real-time PCR for detecting living cells of Z. rouxii was compared. PMAXX was chosen as the added agent because of its better performance. The optimal concentration of PMAXX was found to be 76.92 μM in cell solution (the cell concentration was 1.0 × 108 CFU/mL). The LODs of PMAXX-qPCR in detecting Z. rouxii in pure MEA and honey solution were found to be 103 and 101 CFU/mL, respectively. Living Z. rouxii cells in 18 real honey samples were detected using this PMAXX-qPCR method and compared with the plate count method. The two methods showed consistent detection results in ten negative samples. In the other eight plate count zero but PMAXX-qPCR-positive samples, further verification experiments showed that six of the PMAXX-qPCR-positive samples contained viable but nonculturable (VBNC) Z. rouxii, while the other two PMAXX-qPCR-positive samples may have contained DNA contamination of Z. rouxii. This method is not only fast and sensitive but also can detect both culturable and viable but nonculturable Z. rouxii. This study provides a promising fast and culture-independent method for the detection of living Z. rouxii cells in honey and honey products.

Numerical Investigation on a Liquid–Gas Ejector for Carbon Dioxide Removal Using Amine Solution: Hydrodynamics and Mass Transfer Evaluation

The present study investigates the hydrodynamics and mass transfer of the liquid–gas ejector using three-dimensional (air–water) and two-dimensional (CO2/air-MEA (Monoethanolamine) solution) computational fluid dynamics (CFD) modeling. For 3D simulation, validation of the CFD results of this ejector with experimental data (error less than 5%) showed high simulation accuracy. The effects of motive liquid flow rate and outlet pressure parameters on the air entrainment rate and air hold-up are also investigated. It was found that by increasing the outlet pressure by about 70% (from 3587 to 6127 Pag), the rate of gas entrainment and gas hold up decreased by about 37% and 20%, respectively. On the contrary, these parameters showed increasing behavior of about 74% and 15%, respectively, when the mass flow rate of liquid increased by about 21%. In addition, three-dimensional phenomena such as mixing shock and the location of its occurrence are examined, which is the reason for recirculation and vortex in the ejector. Next, by simulating a two-dimensional simulation and changing the inlet fluids to CO2/air-methanol amine, the ejector was designed to simultaneously increase the gas pressure and absorb carbon dioxide. A user-defined function code was used to express the mass transfer from the gas to the liquid phase. The results, in this case, showed that with increasing the outlet pressure of the ejector (from 0 to 2000 Pag), and enhancing the concentration of MEA solution (from 10% to 30%), the CO2 removal boosted from 83% to 95%. A similar behavior was shown when the L/G ratio increased from 3.5 to 5.5. This study serves as a showcase on how to do an exact design and analysis for liquid–gas ejectors in flare gas recovery systems.

Improved quasi-cycle capacity method based on microcalorimetry strategy for the fast screening of amino acid salt absorbents for CO2 capture

Reaction rate and energy consumption are important factors that determine whether the chemical absorbent is suitable for capturing carbon dioxide (CO2). In this work, a high-precision microcalorimetry instead of the traditional estimation method based on the Gibbs-Helmholtz equation was used to directly measure the CO2 absorption heat of six amino acid salt absorbents (potassium taurinate (PT), potassium sarcosinate (PS), potassium L-Prolinate (PL-P), potassium β-Alaninate (Pβ-A), potassium L-Threonine (PL-T), and potassium glycinate (PG)) and the sensible heat of their solutions. In addition, the absorption rate, desorption rate, absorption time, desorption time, and CO2 loading of the absorbents were studied and were integrated into a parameter called the CO2 quasi-cycle capacity to evaluate the reaction rate. Based on thermodynamic data and CO2 quasi-cycle capacity, the absorbent screening method was improved in this work, and PS was identified as a promising absorbent by this method. The CO2 quasi-cycle capacity of the PS solution was similar to that of MEA. In addition, PS solution has the lowest CO2 absorption heat (-75.79 kJ/mol CO2) and the lowest sensible heat which were 14.1% and 23.2% lower than those of MEA solution.

Regenerable solvents mediate accelerated low temperature CO2 capture and carbon mineralization of ash and nano-scale calcium carbonate formation

The dual need to remove CO2 from our emissions and treat alkaline industrial residues such as ash materials motivate the design of innovative pathways to simultaneously capture and convert CO2 into mineralized carbonates. Direct carbon mineralization is one approach that addresses the need to simultaneously treat alkaline industrial residues and mineralize CO2 emissions. Low CO2 solubility in water and slow kinetics at ambient temperature have challenged the direct carbon mineralization of alkaline industrial residues. To address these challenges, the use of CO2 capture solvents that enhance CO2 solubility and facilitate accelerated carbon mineralization of fly ash at temperatures below 90 °C is investigated. Calcium carbonate formation results in the inherent regeneration of the solvent. The carbon mineralization extents of non-calcium carbonate content in fly ash were 50% and 51% and in waste ash were 58% and 62% in 2.5 M sodium glycinate and 30 wt% MEA solutions, respectively. The experiments were performed at 50 °C for 3 h with CO2 partial pressure of 1 atm in a continuously stirred slurry environment with 15 wt.% solid. Furthermore, nanoscale CaCO3 is successfully synthesized from dissolved calcium using CO2-loaded sodium glycinate and surfactants such as CTAB (Cetyl Trimethyl Ammonium Bromide). Surfactants such as CTAB bind to the calcium carbonate surface and regulate the growth of calcium carbonate particles. These innovative approaches demonstrate the feasibility of directly storing CO2 in fly ash and waste ash as calcium carbonate and producing nanoscale calcium carbonate using regenerable CO2 capture solvents.

Enhancement of CO2 removal by promoted MDEA solution in a hollow fiber membrane contactor: A numerical and experimental study

In this work, carbon dioxide (CO2) loading capacity of methyldiethanolamine (MDEA) solution promoted by potassium lysinate (KLys) was experimentally measured by using a gas absorption setup at different concentrations and temperatures. The CO2 removal efficiency of the MDEA + KLys solution was investigated for a CO2/N2 gas mixture by using computational fluid dynamic (CFD) simulations in a hollow fiber membrane contactor (HFMC). The effects of operating conditions including solvent concentration, solvent flow rate, gas flow rate, inlet CO2 concentration and module length on the CO2 removal efficiency were also studied. The experimental results revealed that CO2 loading capacity increases with increasing KLys concentration in the solution, while decreases as temperature increases. The simulation results indicated that MDEA + KLys solution has higher CO2 removal efficiency compared to pristine MDEA and MEA solutions. The CO2 removal efficiency increases with increasing solvent concentration, solvent flow rate and module length, whereas decreases as gas flow rate increases. The zeolitic imidazolate framework-8 (ZIF-8), as sorbent, was then incorporated into the MDEA + KLys solution and its effect on the CO2 removal efficiency was also examined. The MDEA + KLys + ZIF-8 nano-absorbent showed higher CO2 removal efficiency than that of MDEA + KLys absorbent, where introducing 0.4 wt.% ZIF-8 enhanced CO2 removal from ⁓96% to ⁓99%. The results of this work suggest that both MDEA + KLys absorbent and MDEA + KLys + ZIF-8 nano-absorbent are promising candidates for CO2 absorption processes. However, for practical use as well as a complete investigation, their behavior should be assessed by using other parameters of solvent such as reactivity with CO2, corrosion rate, and regeneration performance.

A Pilot Solvent Comparison Study of Mea and Aeea Water Solutions

A Pilot Solvent Comparison Study of Mea and Aeea Water Solutions

The CO2 removal of flue gas using hollow fiber membrane contactor: a comprehensive modeling and new perspectives

In this study, a novel hollow fiber membrane contactor (HFMC) under a non-wet condition was numerically explored by CFD techniques based on the finite element method to capture CO2 from the CH4/CO2 gas mixture. A new design, such as a shell and tube heat exchanger with baffles, was proposed. The MEA, DEA, and TEA, as different amines solutions, were selected as the liquid solvents. A CO2-containing gas mixture and amine solution were passed in the shell side and the tube side of the membrane contactor, respectively. The simulation findings indicated a good agreement with the reported experimental data demonstrating that such a model would evaluate the effects of different parameters during the HFMC system. Specifically, the results showed that the baffles' presence improved the separation efficiency due to the increased residence time on the shell side. The results also indicated that the MEA solution had the highest CO2 absorption. In the new design (shell and tube heat exchanger with baffles), the rising solvent inlet velocity, decreasing gas velocity, and counter-current flow pattern positively affected separation efficiency.

Improvement of marine carbon capture onboard diesel fueled ships

There is an urgent need to reduce the CO2 emissions from global shipping. This study developed efficient sea-based CO2 capture, CO2 compression and liquefaction for a 3000 kW diesel engine. Several mixed solvents, an intercooler and multiple feeds are used to improve CO2 removal in the absorber. A square-shape is adopted to reduce space, which is in scarce supply in marine applications. Heat integration is applied to enhance the performance of the stripper. An effective configuration is developed for marine CO2 capture to improve the absorber, stripper, CO2 compression and liquefaction. Mono-ethanolamine/piperazine (MEA/PZ) and N-methyl-diethanolamine (MDEA)/PZ increases by 1.7% and 2.8% in terms of CO2 removal compared to the MEA solution, respectively. The MDEA/PZ process with the intercooler and MDEA/PZ process with multiple feeds achieve 90.6% and 90.5% CO2 removal, respectively. The configuration using MDEA/PZ as a solvent, and the combined use of the intercooler, multiple feeds and heat integration demonstrate advantages for ship-based carbon capture. The CO2 removal for the final configuration is 1348 kg/h (94.7%); this is an 8.4% increase compared to the base case. Additionally savings of 100.0%, 18.3%, and 4.0% are achieved in terms of stripper duty, compressor duty in CO2 compression and CO2 liquefaction, respectively.