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Physical N2O solubility in pure 2-(ethylamino)ethanol (EAE) solvent was measured over the temperature range 289.6– 349.7 K. The physical solubility of CO2 in EAE was then derived via the “N2O analogy” method. The effect of structural characteristics such as carbon chain length, hydroxyl group, hydroxylmethyl group and amino group on the physical CO2 solubility was revealed through the comparison of various amines to determine the most advantageous structure for high physical solubility. The physical heat of CO2 absorption of the amine was correlated using Arrhenius equation to analyse the sensitivity of the solubility data to the temperature change. Likewise, physical N2O solubility in aqueous EAE solution was measured from 289.6 to 349.7 K and EAE concentration from 7.5 to 75.0 wt%. To correlate the solubility data in a binary EAE-H2O system, four mathematical models, polynomial, semi-empirical, Redlich-Kister equation and Arrhenius equation models were introduced with average absolute relative deviation (AARD) of 6.5%, 8.7%, 5.9% and 8.7%, respectively. A small extrapolation with respect to temperature at 283 and 363 K was made to further estimate the performance of these models.

The solubility constant of N2O in aqueous 1-dimethylamino-2-propanol (1DMA2P) solution in the concentration range of 0–3.0 mol/L was measured over the temperature range of 298–333 K, and the data used to fit existing models: Redlich-Kister, semi-empirical, and polynomial. A new model has also been developed to predict the solubility constant. Also, N2O diffusivity in aqueous 1DMA2P solution was measured over the concentration range of 0.5–2.0 mol/L and temperature range of 298–313 K. All models used fitted the solubility constant of N2O solubility in 1DMA2P solution data with absolute average deviations (ADDs) for the Redlich-Kister, semi-empirical, polynomial models and a new model of 12.2%, 8.1%, 0.2% and 2.2%, respectively. The data for N2O diffusivity in aqueous 1DMA2P solution were represented by the modified Stokes-Einstein and semi-empirical models (AADs of 2.3% and 13.6%, respectively). A new mechanism-based model was equally developed to better correlate experimental results and understand the process of diffusivity.

This work investigates the carbon dioxide (CO2) equilibrium solubility of seven novel tertiary amines, which include 1-(2-Hydroxyethyl)pyrrolidine (1-(2-HE)PRLD), 4-((2-hydroxyethyl)(ethyl)amino)-2-butanol (HEEAB), 3-diethylamino-1,2-propanediol (DE-1,2-PD), 4-(dipropylamino)-2-butanol (DPAB), 1-(2-Hydroxyethyl)-piperidine (1-(2-HE)PP), 4-((2-hydroxyethyl)(methyl)amino)-2-butanol (HEMAB) and 4-(dimethylamino)-2-butanol (DMAB). This analysis study was conducted at the amine concentration of 2.0 mol/L, over the temperature range of 298–333 K, and over the CO2 partial pressure range of 3–101 kPa. Two approaches were adopted in this study. Some thermodynamic models were employed to correlate and predict the experimental results of CO2 equilibrium solubility in the seven novel tertiary amines solution. The new Helei-Liu model and Liu et al. model for K2 correlation were also developed. A comparison of the performances of these models in predicting CO2 solubility showed that the Liu et al. model, which included the significant parameters of temperature, concentration of amine solution, physical solubility of CO2, and total pressure, gave the best performance in predicting CO2 equilibrium solubility in the newly formulated amine solutions. In addition, the artificial neutral network (ANN) approach was adopted for predicting the CO2 equilibrium solubility of the seven tertiary amines. The predicted values of CO2 solubility extracted from the ANN models were compared with those from the thermodynamic models in terms of the absolute average deviation (AAD).

In this work, nonaqueous binary absorbents were investigated for CO2 capture by mixing conventional amines (i.e. monoethanolamine MEA, methyldiethanolamin MDEA) and ionic liquids. Four ionic liquids [BMIM]BF4, [BEIM]BF4, [BPIM]BF4 and [BBIM]BF4 were synthesized. The thermal stability of the ionic liquids was evaluated and viscosity was measured over the temperature range of 298–348 K. The CO2 absorption performance of the pure ionic liquids was studied at ambient pressure and compared with the hybrid absorbents. The influence factors including temperature, stir rate and cycling numbers were then investigated. Finally, the CO2 absorption mechanism was verified using NMR spectroscopy. Results showed that additional amine could greatly promote the CO2 absorption performance of ionic liquids and mixed absorbents revealed different CO2 absorption behavior depending on the amine type. This work proved that the mixed absorbent MDEA + [BEIM]BF4 yields high cycling CO2 capacity, energy saving, good regenerability and especially, low viscosity.

In this work, the equilibrium CO2 solubilities of five tertiary amines, namely Triethanolamine (TEA), N-methylethanolamine (MDEA), 2-(Dimethylamino)ethanol (DMEA), 3-dimethyl-amino-1-propanol (3DMA1P), and Diethylethanolamine (DEEA) were measured over the temperature range of 298.15–313.15 K, and at CO2 partial pressures up to 60.8 kPa. The activity-structure relationship was studied on the molecular level to account for the differences in equilibrium CO2 solubility. The M-KE model was applied to correlate the vapor-liquid-equilibrium data of the five tertiary amine-H2O-CO2 systems. Results show that the model is able to correlate experimental data very well and gives reasonable prediction results with average absolute deviation (AAD) of 2.5% for TEA, 3.3% for MDEA, 1.3% for DMEA, 1.0% for 3DMA1P and 0.8% for DEEA. In addition, the CO2 absorption heat was calculated using the Clausius-Clapeyron equation. The potential for the five amines to be considered as alternative solvents for CO2 capture was evaluated in terms of equilibrium CO2 solubility, second order reaction rate constant and CO2 absorption heat.

To enhance the energy efficiency of the CO2 desorption process, the regeneration behaviors of the CO2-loaded 6 M MEA-AMP-PZ (monoethanolamine, 2-amino-2-methyl-1-propanol and piperazine) tri-solvent blends with different AMP/PZ molar ratios with four different solid acid catalysts (H-ZSM-5, γ-Al2O3, SAPO-34 and SO42−/TiO2) and a blank at 96 °C were investigated in terms of CO2 desorption rate, cyclic capacity and relative heat duty. For the no-catalytic runs, the results showed that all the tri-solvent blended amines greatly increased CO2 desorption rate, cyclic capacity and decreased the relative heat duty in comparison with 5 M MEA. The 13C NMR analysis indicated that the 3 M MEA-2.5 M AMP-0.5 M PZ blend with the highest AMP/PZ ratio produced the largest amount of bicarbonate and less carbamate, which resulted in the best desorption performance. With regard to catalyst, when the solid acid catalysts were introduced, the regeneration performance of the blend was further improved. The best of the blends along with H-ZSM-5 provided the combination with the best performance in CO2 desorption, and reduced the relative heat duty by 61.6% as compared to 5 M MEA without catalyst (100%). Five relevant physicochemical properties of the catalyst were obtained and used to better understand the catalytic regeneration process. A possible catalytic CO2 desorption mechanism was analyzed. The results revealed that the mesopore surface area coupled with total acid sites of the catalyst had the most positive influence on improving the CO2 desorption performance. Findings from this work imply that the combination of solid acid catalyst with tri-solvent blended amines is a promising alternative method for further reduction of solvent regeneration energy requirement.

In this work, the equilibrium CO2 solubilities of the aqueous N-(2-hydroxyethyl) pyrrolidine (N-(2-HE) PRLD) at different concentrations (1.0 mol/L–5.0 mol/L) were measured at different temperatures (298 K–333 K) and pressures (8 kPa–101 kPa), using a vapor–liquid equilibrium apparatus. Four semi-empirical thermodynamic models (Cf model, Kent–Eisenberg model, Hu–Chakma model and Li–Shen model) were used to correlate and predict the CO2 solubility data of the N-(2-HE) PRLD-CO2–H2O system. The results showed that the Hu–Chakma model, which is one of the models that incorporates the effect of amine concentration and CO2 loading, and accounted for nonideality caused by higher temperature, species concentrations and CO2 loadings, was best able to predict results that are in agreement with the experimental vapor–liquid equilibrium measurements in this work.

In this work, the performance of CO 2 absorption into aqueous 2-amino-2-methyl-propanol (AMP) solution was investigated by measuring the amount of CO 2 in the liquid phase during CO 2 absorption process to identify initial CO 2 absorption rate. Then, the porous media material named as MCM41 was introduced into the amine solution to test its influence on CO 2 absorption. It was found that MCM41 increased initial CO 2 absorption rate and enhanced CO 2 absorption process. The physico-chemical properties of MCM41 were characterized in terms of specific surface area, average pore diameter, total pore volume and chemical properties, the amount of acidic sites and the Brϕnsted/Lewis (B/L) acid sites ratio. Results showed that MCM41 was a type of Lewis acid catalyst with large specific surface area and pore volume. In addition, the pKa of AMP solution with and without MCM41 was obtained using acid titration technology to help understand the effect brought by MCM41. A mechanism illustrating how MCM41 increases the CO 2 absorption rate of the AMP solution was proposed and demonstrated that MCM41 is a potential material for enhancing CO 2 absorption.

The absorption/desorption performance of carbon dioxide (CO2) in aqueous 5 M monoethanolamine (MEA) solutions in the presence of various solution regeneration promoters was comprehensively investig...

The physical properties of densities, viscosities, and refractive indices, which are important in kinetics and mass transfer processes were measured for aqueous CO2-loaded and -unloaded (EAE) solutions applied in CO2 absorption in the temperature range from 293.15 to 323.15 K at atmospheric pressure. Due to the limitation of the instrument and corrosive behavior with increasing concentration, the mass fractions (w1) of aqueous EAE solutions selected were: as 0.089, 0.178, 0.267, and 0.356, which correspond to the molar concentrations of 1, 2, 3, and 4 mol·L–1, respectively. The determined density, viscosity and refractive index data for binary EAE+H2O and ternary CO2+EAE+H2O systems were correlated using Weiland et al. model, Redlich–Kister equation, extended Arrhenius equation, and a new proposed empirical function. All the calculated density, viscosity, and refractive index data fitted well with experimental values at all operational conditions.

In this work, the CO2 equilibrium solubility in 1-dimethylamino-2-propanol (1DMA2P) solution was determined as a function of 1DMA2P concentration (over the range of 1–5 M), temperature (in the range of 298–333 K), and CO2 partial pressure (in the range of 8–101 kPa), and the data used to fit the correlations for K2 using Kent-Eisenberg, Austgen, Li-Sheng and Hu-Chakma models. A new K2 correlation model was also developed to predict the CO2 equilibrium solubility in 1DMA2P solution. It was found that all of the models could fit the CO2 equilibrium solubility in 1DMA2P solution data with absolute average deviations (ADDs) for the models by Kent-Eisenberg, Austgen, Li-Sheng, Hu-Chakma and Liu et al. of 14, 15, 12, 6.3 and 10%, respectively. In addition, the heat of CO2 absorption in 1DMA2P solution estimated using Gibbs-Helmholtz equation was found to be −31.67 kJ/mol. Information or guidelines about effective utilization of data of screened solvents is provided based on three absorption parameters, namely, CO2 equilibrium solubility, second order reaction constant, and CO2 absorption heat.

In this work, the CO 2 equilibrium solubility of 3-dimethylamino-1-propanol (3DMA1P) is presented over the concentration range of 1–3 mol/L, the temperature range of 298–333 K, and the CO 2 partial pressure of 3–101 kPa. Several thermodynamic models (i.e. Kent-Eisenberg model, Austgen model, Hu-Chakma model, Liu et al. model) were used to correlate and predict the CO 2 equilibrium solubility of 3DMA1P solution. It was found that the Liu et al. model could be considered to be an appropriate model to predict the CO 2 equilibrium solubility in 3DMA1P solutions with an absolute average deviation (ADD) of 9.4%. In addition, the ANNs models (BPNN and RBFNN model) were developed and used to correlate the CO 2 equilibrium solubility of 3DMA1P. It was found that the ANNs models could predict the experimental values very well with excellent ADDs of 3.0% for the BPNN model and 4.4% for the RBFNN model, respectively. In addition, a comparison of thermodynamic models and ANN models was presented in terms of prediction of CO 2 solubility in 3DMA1P solution.

In this work, the speciation (i.e., 1DMA2P molecule as well as 1DMA2PH+, HCO3–, and CO32– ions) for the CO2 reactive absorption of CO2 in aqueous 1-dimethylamino-2-propanol solution (i.e., into a 1DMA2P–H2O–CO2 system) was studied using the 13C nulcear magnetic resonance (NMR) technique at a temperature of 301 K over the 1DMA2P concentration range of 0.5–2.0 mol/L and CO2 loading range of 0–1.0 mol CO2/mol amine. Also, in addition to other material conservation laws, a new criterion for selection of the protonation calibration curves, the charge balance of the 1DMA2P–H2O–CO2 system, was added in order to generate results with better accuracy. In addition, the equilibrium constants, K1 and K5, were also obtained using the NMR technique, which had good agreement with those from other works with absolute average deviations of 2.2% and 3.5%, respectively.

In this work, the reaction kinetics of carbon dioxide (CO2) with diethylenetriamine (DETA)in methanol and ethanol systems were measured using the stopped flow technique over a temperature range of 293-313K in terms of pseudo first-order rate constant (k0). Concentration in the range of 10 to 50 mol/m3 for diethylenetriamine were studied. The experimental data show that the pseudo first-order rate constants (k0) increase with the increase of both amine concentration and temperature. The zwitterion mechanism and the termolecular mechanism were used to representthe data for DETAinmethanol and ethanol systems with excllent ADDs of 3.5%, 2.4%, respectively. In comparison with EDA and AEEA in terms of k2, DETA exhibits a better reaction kinetics performance for capturingCO2. Those results will be useful in finding an efficient method for the removal of CO2 from industrial gases.

In this work, various single and blended amines (namely, MEA, MEA-DEEA, MEA-MDEA, MEA-1DMA2P) with three types of catalysts (H-ZSM-5, MCM-41 and SO 4 2- /ZrO 2 ) were studied to determine the respective roles of catalyst and solvent in heat duty for solvent regeneration and rate of CO 2 desorption during the desorption of CO 2 from the solvents having an initial CO 2 loading of 0.5 mol CO 2 /mol amine at 371 K. The results show that performance of the three catalysts in all the four investigated aqueous solution systems followed the trend: H-ZSM-5 > MCM-41 > SO 4 2- /ZrO 2 . These results highlight the fact that even though HZSM-5 has moderate acidic sites (MAS) as compared to MCM-41 and SO 4 2- /ZrO 2 , its large Brϕnsted/Lewis (B/L) acid sites ratio coupled with mesopore surface area (MSA) had the greatest effect on heat duty for CO 2 desorption as well as rate of CO 2 desorption. Furthermore, based on this study, the blended system of aqueous 5 M MEA+1 M MDEA with H-ZSM-5 provided the best approach for solution regeneration because the strong electron withdrawing chemical structure of MDEA made the solution most prone to CO 2 desorption as compared with 1DMA2P and DEEA.

In this work, 13 C NMR spectroscopy was used to study the reaction process of the 2.0 M blended amine of MEA-DEA (1:1) with CO 2 . The concentrations of free amines, the carbamates of amines, protonated amines, HCO 3 − and CO 3 2− in the solutions were generated over the CO 2 loading range from 0 to 0.7 mol CO 2 /mol amine at the temperature of 301K in order to understand the specific process of the reaction between the blended amine and CO 2 . The results show that only the carbamate of MEA was generated under lower CO 2 loading, which means that MEA is more competitive than DEA, while when the CO 2 loading, the carbamate of DEA (namely, DEACOO − ) was also generated, which means that when the CO 2 loading reached 0.231 mol CO 2 /mol amine and the concentration of MEA was decreased a certain extent, the abilities of MEA and DEA to react with CO 2 were well-matched.

Various single and blended amines (namely, MEA(monoethanolamine), MEA-DEEA (2-diethylamino ethanol), MEA-MDEA (methyldiethanolamine), MEA-1DMA2P (1-dimethylamino-2-propanol)) with three types of catalysts (H-ZSM-5, MCM-41 and SO42–/ZrO2) were studied to determine the respective roles of catalyst and solvent in heat duty and CO2 desorption rate with an initial CO2 loading of 0.5 mol CO2/mol amine at 371 K. The results show that performance of the three catalysts in all the four investigated aqueous solution systems followed the trend: H-ZSM-5 > MCM-41 > SO42–/ZrO2. These results highlight the fact that even though HZSM-5 has moderate acidic sites as compared to MCM-41 and SO42–/ZrO2, its large B/L acid sites ratio coupled with mesopore surface area had the best performance. Furthermore, based on this study, the blended system of aqueous 5 M MEA+1 M MDEA with H-ZSM-5 provided the best approach for solution regeneration because the strong electron withdrawing chemical structure of MDEA.

In this work, the equilibrium solubility of CO2 in a 1-diethylamino-2-propanol (1DEA2P) solution was determined as a function of 1DEA2P concentration (over the range of 1–2 M), temperature (in the range of 298–333 K), and CO2 partial pressure (in the range of 8–101 kPa). These experimental results were used to fit the present correlation for K2 (Kent-Eisenberg model, Austgen model, and Li-Shen model). It was found that all of the models could represent the CO2 equilibrium solubility in 1DEA2P solution with ADDs for Kent-Eisenberg model, Austgen model, and Li-Shen model of 6.3, 7.3, and 12.2%, respectively. A new K2 correlation model, the Liu-Helei model, was also developed to predict the CO2 equilibrium solubility in 1DEA2P solution with an excellent ADD of 3.4%. In addition, the heat of absorption of CO2 in 1DEA2P solution estimated by using the Gibbs-Helmholtz equation was found to be −45.7 ± 3.7 kJ/mol. Information and guidelines about effectively using data for screened solvents is also provided based on the three absorption parameters: CO2 equilibrium solubility, second order reaction constant (k2), and CO2 absorption heat. © 2017 American Institute of Chemical Engineers AIChE J, 63: 4465–4475, 2017

In this work, the novel tertiary amines, 4-(dimethylamino)-2-butanol (DMAB), 4-(dipropylamino)-2-butanol (DPAB), 4-((2-hydroxyethyl)(methyl)amino)-2-butanol (HEMAB) and 4-((2-hydroxyethyl)(ethyl)amino)-2-butanol (HEEAB), 1-(2-Hydroxyethyl)-piperidine (1-(2-HE)PP), 1-(2-Hydroxyethyl)pyrrolidine (1-(2-HE)PRLD) and 3-diethylamino-1,2-propanediol (DE-1,2-PD) were synthesized or screened to reduce energy requirement of PCC to 2.0GJ/ton CO2. The CO2 equilibrium solubility of those solvents were provided. A new K2 correlation model, Liu et al. model, was also developed to correlate and predict the CO2 equilibrium solubility in those new amines solution. It was found that the new model could fit the CO2 equilibrium solubility in those newly solution with absolute average deviations (ADDs) for DMAB, DPAB, HEMAB, HEEAB, 1-(2-HE)PP, 1-(2-HE)PRLD, DE-1,2-PD of 5.4%, 24.7%, 8.3%, 4.2%, 1.7%, 4.1%, and 2.3%, respectively.

The stopped-flow technique was applied on the measurement of the kinetics of carbon dioxide (CO2) absorption into aqueous blends of monoethanolamine (MEA) and diethanolamine (DEA) over the temperature range of 293–313 K. The investigation of blended MEA + DEA with various molar ratios of DEA to MEA revealed that the reaction mechanism between CO2 and blended absorbents could be different at different ratio of DEA to MEA. Consequently, the kinetic data obtained in this work was split into two groups with respect to the different molar ratios of DEA to MEA in order to study the different mechanisms. In group A, the concentration of MEA was in the range of 5–15 mol/m3 and the concentration of DEA was low (varied between 5 and 15 mol/m3), while in group B, the DEA concentration was high (varied between 140 and 240 mol/m3) and the concentration of MEA remained in the range of 5–15 mol/m3. Modified models based on the termolecular mechanism were developed for each group and used to interpret the experimental kinetic data. Results showed that the models could explain the data well with an AAD of 4.71% for group A at low concentration of DEA and 3.33% for group B at high concentration of DEA. It is interesting to point out that DEA barely reacts with CO2 at low molar ratios (i.e. group A) whereas at high DEA concentration (i.e. group B), both MEA and DEA reacted with CO2.

The CO 2 absorption performance of aqueous 1-(2-hydroxyethyl)pyrrolidine (1-(2-HE)PRLD) was studied with respect to kinetics (i.e., in terms of the pseudo-first-order rate constant ( k o ) and second-order reaction rate constant ( k 2 ), obtained using the stopped-flow apparatus). CO 2 equilibrium solubility and heat of CO 2 absorption were evaluated at the temperature range of 293–313 K in the 1-(2-HE)PRLD concentration range of 0.20–1.00 mol/L for kinetics and at 2 M for CO 2 solubility. The values of k o were then represented using the base-catalyzed hydration mechanism, which gave an acceptable AAD of 10%. In addition, Bronsted plots of k 2 vs. pKa were developed to predict k 2 using pKa values of various tertiary amines. In addition, the CO 2 equilibrium solubility and CO 2 absorption heat were obtained in this work. Based on a comparison with other amines such as MEA, MDEA and 1DMA2P, 1-(2-HE)PRLD showed better performance in terms of CO 2 equilibrium solubility (DEAB > 1-(2-HE)PRLD > 1-(2HE)PP > 1DMA2P > MDEA > MEA > DEA), kinetics (MEA > DEA > DEAB > 1-(2-HE)PRLD > 1-(2-HE)PP > DMMEA > 1DMA2P > MDEA.) and CO 2 absorption heat (MEA > DEA > MDEA > DEAB > 1-(2-HE)PRLD > 1-(2HE)PP > 1DMA2P). Therefore, 1-(2-HE)PRLD could be considered as a good alternative solvent for CO 2 capture. A correlation between kinetics and heat of CO 2 absorption has been developed to guide the design of what can be considered to be ideal amine solvents for CO 2 capture.

In this work, the equilibrium CO2 solubility in the aqueous tertiary amine, N-methyl-4-piperidinol (MPDL) was measured over a range of temperatures, CO2 partial pressures and amine concentrations. The dissociation constant of the MPDL solution was determined as well. A new thermodynamic model was developed to predict the equilibrium CO2 solubility in the MPDL-H2O-CO2 system. This model, equipped with the correction factor (Cf), can give reasonable prediction with an average absolute deviation of 2.0%, and performs better than other models (i.e., KE model, Li-Shen model, and Hu-Chakma). The second-order reaction rate constant (k2) of MPDL and the heat of CO2 absorption (–ΔHabs) into aqueous MPDL solutions were evaluated as well. Based on the comparison with some conventional amines, MPDL revealed a high-equilibrium CO2 loading, reasonably fast absorption rate when compared with other tertiary amines, and a low energy requirement for regeneration. It may, therefore, be considered to be an alternative solvent for CO2 capture. © 2017 American Institute of Chemical Engineers AIChE J, 63: 3395–3403, 2017

In this work, three promising tertiary amines—1-(2-hydroxyethyl)piperidine (1-(2-HE)PP), 3-(diethylamino)-1,2-propanediol (DEA-1,2-PD), and N-(2-hydroxyethyl)pyrolidine (1-(2-HE)PRLD)—were experimentally studied and the results presented in terms of pKa, the protonation calibration curves, and ion speciation plots. The pKa of these amines were determined in the temperature range of 294–320 K. The protonation calibration curves for the three amines were also developed based on 13C NMR detection. In addition, ion (amine, amineH+, HCO3–, and CO32–) speciation plots for the three tertiary amines were developed at the temperature of 298 K, at the amine concentration of 1.0 M, over the CO2 loading ranges of 0–0.897 mol CO2/mol amine for 1-(2-HE)PP, 0–0.915 mol CO2/mol amine for DEA-1,2-PD, and 0–0.927 mol CO2/mol amine for 1-(2-HE)PRLD by using the pH method, the 13C NMR method, and the pH + 13C NMR method. By comparing the ion (amine, amineH+, HCO3–, and CO32–) concentrations of the three tertiary amines obtai...

In this present work, the CO2 absorption performance of aqueous 1-diethylamino-2-propanol (1DEA2P) solution was studied with respect to CO2 equilibrium solubility, absorption kinetics, and absorption heat. The equilibrium solubility of CO2 in 2M 1DEA2P solution was measured over the temperature range from 298 to 333 K and CO2 partial pressure range from 8 to101 kPa. The absorption kinetics data were developed and analyzed using the base-catalyzed hydration mechanism and ANN models (RBFNN and BPNN models) with an acceptable AAD of 10% for base-catalyzed hydration mechanism, 2.6% for RBFNN model and 1.77% for BPNN model, respectively. The CO2 absorption heat of 1DEA2P was estimated to be -43.6 kJ/mol. In addition, the ion (1DEA2P, 1DEA2PH+, HCO3-, CO32-) speciation plots of the 1DEA2P-CO2-H2O system were developed in order to further understand the reaction process of 1DEA2P with CO2. Based on a comparison with conventional amines (e.g. MEA, DEA, MDEA) and alternative amines (i.e.1DMA2P and DEAB), 1DEA2P exhibited good performance with respect to CO2 equilibrium solubility, reaction kinetics, and CO2 absorption heat. Meanwhile, the overall evaluation of 1DEA2P for application in CCS in terms of absorption and desorption is presented, giving helpful information for the screening of these novel amines. This article is protected by copyright. All rights reserved.

This work examined the relationship between the structure of various commercial tertiary amines and their activity in CO 2 absorption/desorption in terms of rate of CO 2 absorption, equilibrium CO 2 loading, p K a and heat of CO 2 absorption in order to establish possible guidelines for selection of tertiary amine components for amine blends. Results show that any electron donating group linked directly to the nitrogen atom increases their reactivity with CO 2 . In addition, the presence of steric hindrance effect and good water solubility also show enhancements in activity. In contrast, the existence of a hydroxyl group leads to a decrease in all the activity of the tertiary amine. The heat of CO 2 absorption of tertiary amines, which is closely related to the regeneration energy, can be reduced by decreasing the number of hydroxyethyl groups or by positing the hydroxyl group at the proper carbon relative to the nitrogen atom.

Blended absorbents composed of N,N-diethylethanolamine (DEEA) and amine activator were comprehensively studied using an improved rapid screening method. A total of nine amine activators, including MEA, DEA, EEA, AMP, AEEA, MAPA, DETA, TETA, and PZ, were assessed based on absorption rate, stripping rate, and cyclic CO2 capacity. The rapid screening experiments for the absorption and stripping were conducted at 40 and 80 °C, respectively. Results revealed how the absorption/stripping performance is affected by the number and structure of −NH– groups in the activators. In addition, all of the 3 M DEEA-based solutions showed improved absorption rate and regeneration rate as well as cyclic CO2 capacity with the use of 3 M DEEA and 5 M MEA individually. Furthermore, experimental results showed that the highest average absorption rate, average desorption rate, and cyclic CO2 capacity of 1.6272 mol CO2/L were achieved by an aqueous DEEA-PZ solution.

In this work, the reaction kinetics of carbon dioxide (CO2) with diethylenetriamine (DETA) and 1-amino-2-propanol (1-AP) in methanol and ethanol systems were measured using the stopped flow technique over a temperature range of 293-313 K in terms of pseudo-first-order rate constant (k0). Concentration in the range of 10 to 50 mol/m3 for diethylenetriamine, and 20 to 100 mol/m3 for 1-amino-2-propanol were studied. The experimental data show that the pseudo-first-order rate constants (k0) increase with the increase of both amine concentration and temperature. The zwitterion mechanism and the termolecular mechanism were used to represent the data for DETA in methanol and ethanol systems with excellent ADDs of 3.5% and 2.4%, respectively, and 1-AP in methanol and ethanol systems with excellent ADDs of 2.4% and 2.6%, respectively. In comparison with EDA and AEEA in terms of k2, DETA exhibits a better reaction kinetics performance for capturing CO2. Those results will be useful in finding an efficient method for the removal of CO2 from industrial gases. The financial support from the National Natural Science Foundation of China (NSFC Nos. 21536003, 21476064, U1362112, 21376067 and 51521006), National Key Technology R&D Program (MOST Nos. 2012BAC26B01 and 2014BAC18B04), Innovative Research Team Development Plan (MOE-No. IRT1238), Specialized Research Fund for the Doctoral Program of Higher Education (MOE No. 20130161110025), China's State "Project 985" in Hunan University-Novel Technology Research & Development for CO2 Capture, Key Project of International & Regional Cooperation of Hunan Provincial Science and Technology plan (2014WK2037), and China Outstanding Engineer Training Plan for Students of Chemical Engineering & Technology in Hunan University (MOE No. 2011-40), NPRP Grant # 7-1154-2-433 from the Qatar National Research Fund (a member of Qatar Foundation) and China Scholarship Council (CSC) are gratefully acknowledged. Scopus

The formation of bicarbonate ions in an amine solution during CO2 absorption results in lowering the heat duty for amine solvent regeneration in the CO2 capture process because bicarbonate breakdown needs the lowest energy input to release CO2. In this study, bicarbonate formation was conducted for two mixed solvents consisting of tertiary amines (1DMA2P (1 M) or MDEA (1 M)) blended with MEA in order to determine both formation rate and capacity of bicarbonate ions as compared to MEA alone. The amines and concentrations used in the study were MEA (5 M), MEA–MDEA (5:1 molar ratio, 6 M total), and MEA–1DMA2P (5:1 molar ratio, 6 M total) at various CO2 loadings. The formation of bicarbonate ions was evaluated using 13C NMR technique at 293.15 K. The results show that for the single tertiary amine system higher concentrations of bicarbonate ions were formed for MDEA than for 1DMA2P for the same CO2 loading. The results for the blended amine systems showed that bicarbonate ions were generated at CO2 loadings l...

Protonation and carbamate formation are critical reactions for CO2 capture using amine-based absorbents which impact both CO2 absorption and amine regeneration. In this regard, thermodynamic analysis towards CO2 absorption in N-methylaminoethanol solution is carried out with specific attention to the corresponding protonation and carbamate formation reactions. The CO2 absorption mechanism is investigated with the acquisition of reaction equilibrium constant and heat of reaction. CO2 absorption performance of N-methylaminoethanol solution was evaluated in terms of CO2 loading and solution pH. A thermodynamic model was then developed to mathematically describe the investigated system and make prediction on equilibrium CO2 solubility, species profiles, and absorption/regeneration heat. Results show that the average relative deviation of equilibrium CO2 solubility calculated from the is 4.2%. The predictive species profile and CO2 absorption heat of N-methylaminoethanol solution indicates less energy cost to desorb CO2. This is in line with the relative unstable N-methylaminoethanol carbamate formation and consequential conversion to (bi)carbonate. The position of N-methylaminoethanol as a potential absorbent in amine based carbon capture is shown in terms of chemical reaction constants, equilibrium CO2 solubility, second order rate constant (k2), and pKa.

The stopped-flow technique was applied for the investigation of kinetics of CO2 absorption into loaded MDEA solution over the range of MDEA concentration of 0.4 to 1.0 kmol/m3, CO2 loading of 0.14 to 0.17 mol CO2/mol amine and the temperature of 293 to 308 K. The kinetics of unloaded MDEA was also investigated for the comparison and a huge difference of results which should be equal theoretically was indicated between loaded and unloaded systems. Then, the effect of CO2 loading on the kinetics was studied. As the loading increases, there is a turning point around loading of 0.10, below which the overall reaction constant decreases strongly. It was found that contribution of hydroxyl is a crucial to overall reaction rate constant and cannot be ignored and the influence of reverse reaction of MDEA and CO2 can be ignored. The kinetics of loaded system obtained in this work was modified and interpreted well by the base-catalyzed mechanism with AARD of 6.29% and compares favorably with literature using gas-liquid apparatus. The kinetics of unloaded system in this work is approximately twice as that of literature and loaded system. This work provided literature review and interpretation of MDEA-CO2-H2O and is hopeful to shed light on kinetic study of CO2 absorption in tertiary amine using stopped-flow apparatus.

In this work, the CO2 equilibrium solubility in 2 M 1-diethylamino-2-propanol (1DEA2P) solution were determined as function of temperature (in the range of 298-333K), and CO2 partial pressure (in the range of 8-101 kPa). The modified Li-shen K2 correlation model was also developed and used to predicate the CO2 equilibrium solubility in 1DEA2P solution. with an excellent ADD of 3.4%. The heat of CO2 absorption in 1DEA2P solution estimated using Gibbs-Helmholtz equation was found to be -45.7 kJ/mol. In addition, the ion (1DEA2P, 1DEA2PH+, HCO3-, CO32-) speciation plots of the 1DEA2P-CO2-H2O system were developed in order to further understand the reaction process of 1DEA2P with CO2. Published by Elsevier Ltd. 2017 The Authors. The financial and equipment supports from the Innovative Research Team Development Plan(MOE-No.IRT1238), Specialized Research Fund for the Doctoral Program of Higher Education (MOE-No. 20130161110025), Key Project of International &Regional Cooperation of Hunan Provincial Science and Technology plan (2014WK2037), and China Outstanding Engineer Training Plan for Students of Chemical Engineering & Technology in Hunan University (MOE-No.2011-40), and China Scholarship Council (CSC) are gratefully acknowledged. In addition, the financial and equipment supports from the Natural Sciences and Engineering Research Council of Canada (NSERC), Gas Processing Centre of Qatar University - QATAR as well as from the Clean Energy Technologies Research Institute (CETRI) of University of Regina, CANADA are gratefully acknowledged. The authors also acknowledge supports from the NPRP Grant # 7 - 1154 - 2 - 433 from the Qatar National Research Fund (a member of Qatar Foundation). Scopus