Experimental CO2 Solubility Data Research Articles

Equilibrium Solubility of CO2 in Aqueous Blend of 2-(Diethylamine)ethanol and 2-(2-Aminoethylamine)ethanol

New experimental CO2 solubility data at equilibrium in an aqueous blend of 2-(diethylamino)ethanol (DEEA) and (2-aminoethyl) ethanolamine (AEEA) have been illustrated for the concentration of CO2 in the inlet gas stream ranging from 10.132 to 20.265 kPa and aqueous amine blend temperature ranging from 303.14 to 333.14 K. Total concentrations of aqueous blend were taken in the range of 1.0–3.0 kmol/m3 and mole fraction of AEEA in total amine blend in the range of 0.02–0.20. Experiments were carried out in a semibatch operated laboratory scale gas–liquid bubbling absorber, and analysis of liquid phase CO2 as a saturated liquid was done by titration method. The equilibrium CO2 solubility in DEEA + AEEA blend was found to be a maximum at the value of 0.843 mol CO2/mol amine with AEEA mole fraction in total amine of 0.2 at 1 kmol/m3 total concentration of amine mixture and 303.14 K. New solubility data of CO2 in the present work was compared with existing literature data. An empirical correlation was developed...

Solubility of carbon dioxide and methane in 1-hexyl-3-methylimidazolium nitrate ionic liquid, experimental and thermodynamic modeling

Abstract Experimental data for solubility of CO2 and CH4 in 1-hexyl-3-methylimidazolium nitrate [Hmim][NO3] at temperature range of 293.15–343.15 K and pressure up to 4 MPa are reported. The solubility of CO2 is higher than that of CH4 in the entire temperature region studied. The experimental data show that the temperature has a little effect on CH4 solubility. The Henry’s constant of both gas in [Hmim][NO3] are calculated and the ideal selectivity of CO2 to CH4 are reported. The ideal selectivity is increased with temperature reduction. The experimental data for CO2 solubility are compared with other types of nitrate based ionic liquids (ILs) at different temperatures and pressure. The results of this comparison reveal that the solubility of CO2 is increased with enlargement the alkyl chain length of IL cation. The experimental data are correlated with the extended Henry’s law model. The virial expansion model of Pitzer is used for interpretation of the activity coefficient of the gases and the interaction parameters of the model are estimated as a function of temperature.

Equilibrium CO2 solubility and thermophysical properties of aqueous blends of 1-(2-aminoethyl) piperazine and N-methyldiethanolamine

The present work reports new experimental CO2 solubility data of CO2 absorption in aqueous mixture of 1-(2-aminoethyl)piperazine (AEP) and N-methyldiethanolamine (MDEA) over the temperature and pressure range of (303.2˗323.2) K and (3–300) kPa, respectively. The total mass fraction for AEP and MDEA was fixed to be yAEP+yMDEA = 0.4 in the aqueous solution. In the experimental measurement, the samples with the five different composition of AEP: MDEA (yAEP:yMDEA) have been considered as 0.05:0.35; 0.10:0.30; 0.15:0.25; 0.20:0.20 and 0.25:0.15 respectively. The experimental solubility data is modeled using modified Kent-Eisenberg (KE) equilibrium model. The equilibrium constants related to AEP deprotonation, and carbamate formation reactions are regressed as a function of CO2 partial pressure, amine concentration and temperature to fit the equilibrium CO2 solubility data. The model predicted VLE results from KE model are in good agreement with the experimental data within an average absolute deviation (AAD) of 5.94%. The solubility data is also correlated using Artificial Neural Network (ANN) approach. The predicted value from the feed forward neural network model, which involves Levenberg-Marquardt algorithm, shows very good agreement with the experimental data having mean square error (MSE) of 0.000413 and correlation coefficient (R2) of 0.997. Thermophysical properties such as density, viscosity and surface tension of aqueous (AEP + MDEA) have been also measured in the temperature range of (303.2–343.2) K. The density and viscosity data is modeled as a function of temperature and amine composition using Redlich-Kister and Grunberg-Nissan models, respectively. The model results of these temperature dependent physical properties are also in good agreement with the experimental data.

Solubility of CO2 in aqueous solutions of glycerol and monoethanolamine

For decades, carbon dioxide emissions have been an environmental and health issue. Amines like Monoethanolamine (MEA) have long been favoured in strategies based on chemical absorption aimed at CO2 capture and thus reduction of its harmful environmental impacts. However, some drawbacks, such as toxicity, low stability and high cost limit widespread adoption of this technology. New and green solvents are a possible solution to this issue. As a part of the present study, CO2 solubility in aqueous solutions of different molar ratios of MEA and glycerol as a green solvent was studied. The CO2 absorption was performed at three different temperatures (303, 318, and 333K) at normal atmospheric pressure, while CO2 partial pressure was varied from 1 to 15kPa, and the gas flow rate in the mixture was changed from 350 to 700ml/min. The response surface methodology (RSM) based on central composite design (CCD) was used to design the experiment and explore the effects of four independent parameters (molar concentration of MEA, molar concentration of glycerol, temperature, and gas flow rate) on the solubility of CO2 in solution. Analysis of variance (ANOVA) results showed a good agreement between the experimental data and the statistical model. The maximum solubility occurred for 4M MEA+2M glycerol at 333K and 350ml/min CO2 flow rate. The CO2 solubility values pertaining to different pressures and concentrations were in good agreement with the general absorption trend. However, as the temperature increased, so did the loading. The findings further revealed that the optimum CO2 solubility was obtained at low glycerol to MEA ratio, as this ensured the solubility at elevated temperatures. As glycerol is a viscous fluid, it can be confirmed that it is a suitable solvent at low pressures and high temperatures. Therefore, it can be a viable alternative solution for post-combustion CO2 capture. In addition, an artificial neural network (ANN) model and correlations of CO2 solubility with CO2 partial pressure for all the studied solvent mixtures were developed in this study. Both the ANN model and the correlations fit the experimental CO2 solubility data reasonably well.

An experimental and modeling study of CO2 solubility in a 2-amino-2-methyl-1-propanol (AMP) + N-methyl-2-pyrrolidone (NMP) solution

In this study, an experimental setup based on the static-synthetic method was used to measure the new experimental data of CO2 solubility in an aqueous solution of 2-amino-2-methyl-1-propanol (AMP) + N-methyl-2-pyrrolidone (NMP) solution. For the static-synthetic method, the mass balance of compositions and the pressure–volume–temperature conditions were used for measuring the amount of absorbed CO2 by the AMP+NMP solution. The measurements were performed over a temperature range of 313.15–353.15 K, CO2 partial pressure up to 316.7 kPa, and in different concentrations of the AMP+NMP solution. Two models, modified Kent–Eisenberg, and Deshmukh–Mather, based on the empirical correlations and activity-fugacity approach, respectively, were used for the prediction of experimental data. The parameters of the equilibrium constants of the protonation and carbamate reactions for the modified Kent–Eisenberg model and the interaction parameters for Deshmukh–Mather model were obtained. For validation of our setup, a new set of experimental data for the solubility of CO2 in an aqueous solution of AMP, methyldiethanolamine (MDEA) and diethanolamine (DEA) were measured and compared with existing experimental data in the literature, and good results were obtained. The results of the modeling study showed that the Deshmukh–Mather model gave a better prediction of experimental CO2 loadings data than the modified Kent–Eisenberg. Also, the results showed that the solubility of CO2 in an aqueous solution of AMP+NMP increases as the CO2 partial pressure increases while the temperature decreases.

Analyzing the experimental data of CO2 equilibrium absorption in the aqueous solution of DEA + MDEA with Random Forest and Leverage method

The continuing production of energy from fossil fuels is responsible for large emissions of CO2 component of greenhouse gases. Employing amine-based solutions is a common approach for removing the produced CO2 in numerous carbon capture systems. In this communication, a novel methodology namely Random Forest (RF) is employed for developing a tree-based predictive tool. The prediction capability of the proposed RF model is compared to the modified Deshmukh–Mather thermodynamic model. The presented RF model shows an average absolute relative deviation percent (AARD%) of 3.74, while the modified Deshmukh–Mather model estimates the CO2 loading capacity of the DEA+MDEA solution with AARD% of 12.10. Furthermore, the reliability and quality of the experimental data for CO2 solubility in DEA+MDEA aqueous solution has been investigated in this study using Leverage algorithm. According to the results, there are two probable doubtful data points in the investigated database.

Experimental measurement and Kent-Eisenberg modelling of CO2 solubility in aqueous mixture of 2-amino-2-methyl-1-propanol and hexamethylenediamine

In this work, vapour-liquid equilibrium of CO2 in aqueous mixture of 2-amino-2-methyl-1-propanol (AMP) and hexamethylenediamine (HMDA) is studied in the temperature and pressure range of 303.15–333.15 K and 1–100 kPa respectively. Concentration of the aqueous solutions used are (5mass% HMDA+25mass% AMP), (10 mass% HMDA+20 mass% AMP), (15mass% HMDA +15mass% AMP) and (20 mass% HMDA+10 mass% AMP). Density of aqueous amine solution is also measured in the same range of temperature and concentration. Redlich-Kister equation for excess molar volume is used to model density of the mixed solvent system. To correlate experimental CO2 solubility data, Kent and Eisenberg thermodynamic model is used. Equilibrium constants of bicarbamate formation reaction of HMDA and deprotonation reaction of AMP are regressed to fit experimental data with the model expression. Kent and Eisenberg model is found to predict the CO2 solubility in aqueous (HMDA + AMP) with good accuracy (AAD: 7.2%).

Modeling the effect of piperazine on CO2 loading in MDEA/PZ mixture

The equilibrium of CO2 solubility and species concentration data for the absorption of CO2 in the aqueous solutions of Methyl-di-ethanolamine (MDEA), Piperazine (PZ) and their mixture (MDEA+PZ) were analyzed using Matlab software. A thermodynamic model was developed to predict the vapor liquid equilibrium of CO2 in aqueous mixtures of MDEA/PZ. The electrolyte-nonrandom two-liquid (e-NRTL) model was used to build the vapor-liquid equilibrium model, which defines equilibrium behavior of the solution. This model was applied to correlate the species concentration in the solutions of MDEA, PZ and their mixtures using default interaction parameters reported in the literature. It was observed that this model gave a good estimation of CO2 loadings over a wide range of operating conditions for both single and mixed amine solutions. The model has been used to estimate the species concentrations and CO2 solubility in aqueous DEA/PZ [1]. The application of this model is new to this system, i.e. of CO2-MDEA-PZ-H2O. In this work, the model was further extended to predict the effect of piperazine on CO2 loading for carbonated aqueous solutions of MDEA/PZ systems. The addition of PZ to MDEA as an activator increased the solubility of CO2 under low and high range of CO2 partial pressures and temperatures. The species concentrations, activity coefficients, and pH of the CO2 loaded solutions were studied, and the model predicts amine volatility as well. The model was validated using the experimental data generated from our previous work and data available in the open literature. The results of the current model are in an acceptable degree of agreement with the experimental data of CO2 solubility reported in previous work for this system.

VLE of CO2 in aqueous potassium salt of L-phenylalanine: Experimental data and modeling using modified Kent-Eisenberg model

In this study, vapor-liquid equilibrium (VLE) of CO2 in aqueous potassium salt of l-phenylalanine (K-Phe) was investigated. A high pressure solubility cell was used to measure the solubility of CO2 in aqueous solution of (10, 20 and 25) wt% K-Phe at 303.15, 313.15 and 333.15 K over a CO2 pressure range of 200–2500 kPa. Equilibrium CO2 solubility was defined in terms of CO2 loading (mole CO2/mole of amine). The effect of temperature, concentration and equilibrium CO2 pressure on CO2 loading was discussed. Experimental CO2 loading data in aqueous K-Phe solutions show that the solvent has good potential for CO2 capture systems. Also, a modified Kent-Eisenberg model was used to correlate the experimental CO2 solubility data and carbamate hydrolysis and amine deprotonation equilibrium constants were regressed as a function of temperature, concentration and equilibrium CO2 pressure. An average absolute deviation of 7.70% between experimental and predicted data indicated the good prediction capability of the applied thermodynamic model.

Measuring mutual solubility in the H2O–CO2 system up to 200 bar and 100 °C by in situ Raman spectroscopy

The solubility control in the H2O–CO2 system under high pressure is of prime interest in numerous geochemical systems from hydrothermal fluids to CO2 geological storage. However, the number of experimental data is scarce in the range of interest of geological storage, especially in the CO2-rich phase. A new experimental device was built to measure mutual solubility in the CO2–H2O system without sampling by coupling a batch reactor with Raman immersion probes. The system was first calibrated by measuring the solubility of CO2 in water at 100°C. The results were provided with an accuracy of a few % between 40bar and 200bar and in agreement with other published experimental data sets and models. The linear correlation between Raman peak intensity and CO2 solubility in the aqueous phase was then used to provide new experimental data of CO2 solubility in water at 65°C from 3bar to 200bar. The Raman data of the CO2-rich phase or supercritical phase are compared to a thermodynamic models and the few experimental data available in literature to provide a new data set of H2O–CO2 mutual solubility at 100°C and up to 200bar.

Effect of piperazine on solubility of carbon dioxide using aqueous diethanolamnie

Experimental results of vapor–liquid equilibrium of this study for CO2 capture in solutions of activated diethanolamine (DEA) are presented at temperatures ranging from 313.15 to 353.15 K. Piperazine (PZ), which is used as an activator in this study, its concentration ranged from 0.01 to 0.1 M. Total alkalinity of the solution was kept 2 M. The partial pressure of CO2 varied from 0.01 to 100 kPa. A thermodynamic model is developed to predict the vapor liquid equilibrium of CO2 in aqueous mixtures of DEA/PZ. For CO2+H2O + DEA + PZ system, the e-NRTL model is used to develop the VLE model, which defines equilibrium behavior of the solution. Model is validated using data generated from this work as well as data available in literature. Results of the current model are in an acceptable degree of agreement with the experimental data of CO2 solubility of this work as well as of those stated in literature. The species concentration, activity coefficients, pH of the CO2 loaded solutions, and the model predicts amine volatility. Addition of PZ to DEA, as an activator, has increased the solubility of CO2 under a specific range of CO2 partial pressure.

Experimental measurement and thermodynamic modeling of CO2 solubility in aqueous solutions of morpholine

In the present work, new experimental data of CO2 solubility in aqueous solutions of 2, 3 and 4.5M (17.5, 26.1 and 39.16wt.%) morpholine (MOR) at two different temperatures (313.15 and 333.15K) is obtained by static method. The Deshmukh–Mather thermodynamic model is performed to calculate CO2 solubility in aqueous MOR solutions. The short-range interaction parameters between ion–ion and ion–molecule species in the activity coefficient model are considered to be function of temperature and are adjusted to experimental data. The model shows good results for the solubility calculations. The overall average absolute relative percent deviation (AAD%) for all the data points of CO2 partial pressure is 9.86%.

Vapor–liquid equilibrium measurement and ENRTL modeling of CO2 absorption in aqueous hexamethylenediamine

In this work, a new experimental data of CO2 solubility in aqueous solution of Hexamethylenediamine (HMDA) have been generated at 30, 40, 50 and 60°C in the CO2 partial pressure range of 1–100kPa. Concentration of aqueous HMDA used for solubility measurement ranges from 10 to 30 mass%. Electrolyte Non-Random Two Liquid (ENRTL) theory is used to correlate and predict vapor–liquid equilibrium (VLE) data. Model predicted data show good agreement with the experimental VLE data with an average absolute deviation of 11.0%. The ENRTL parameters are regressed from the experimental data of CO2 solubility using the data regression system (DRS) of Aspen Plus® (V 7.3). The ENRTL model is also used to predict equilibrium liquid phase speciation, solvent capacity, pH of the solution and heat of absorption of CO2 in aqueous HMDA solution.

Predicting CO2 solubility in aqueous N-methyldiethanolamine solutions with ePC-SAFT

In this work, electrolyte PC-SAFT equation of state developed in 2005 with the parameters from Held et al. [Chem. Eng. Res. Des. 92 (2014) 2884–2897] has been applied to predict the solubility of CO2 in aqueous N-methyldiethanolamine (MDEA) solutions. The considered temperature range was 313–413K, MDEA weight fractions up to 0.32 (related to the binary water/MDEA system) and loadings of up to 1.32 (mole CO2/mole MDEA).In order to predict CO2 solubilities, the reaction equilibria and phase equilibria were solved simultaneously by explicitly accounting for the electrolyte species being present in the system: H+, OH−, HCO3−, CO32− and MDEAH+. The pure-component parameters for the molecular components (H2O, CO2, MDEA) and for all ions except MDEAH+ were already available in the literature. MDEAH+ pure-component parameters were inherited from MDEA, and the charge was explicitly accounted for in ePC-SAFT. Binary parameters were applied only for the pairs H2O/CO2, H2O/ions, and H2O/MDEA. The deviations between experimental and ePC-SAFT modeled CO2 solubility in aqueous MDEA solutions was 19.82% for a temperature range of 313–413K, a MDEA weight fractions of 0.19, and CO2 loadings of up to 1.3 (mole CO2/mole MDEA). As binary parameters have not been adjusted to experimental CO2 solubility data in aqueous MDEA solutions, these results can be considered as predictive.

Prediction of CO2 solubility in bitumen using the cubic-plus-association equation of state (CPA-EoS)

The ability to accurately predict the solubility of CO2 in bitumen is essential to the design of bitumen and heavy oil recovery processes. We applied the cubic-plus-association equation of state (CPA-EoS) to calculate the solubility of CO2 in bitumen and the Soave–Redlich–Kwong (SRK) equation of state was applied to treat the physical molecular interactions. The proposed thermodynamic model was verified against the experimental data for CO2 solubility in bitumen over wide ranges of temperature and pressure for four different bitumens from Alberta reservoirs. The CPA-EoS was able to predict the solubility with less deviation from the experimental data than the regular cubic equations of state and the statistical association fluid theory (SAFT). Our results suggest that the CPA-EoS is an effective method of conducting solubility calculations for solvent assisted bitumen recovery processes.

Determination of cost-effective operating condition for CO2 capturing using 1-butyl-3-methylimidazolium tetrafluoroborate ionic liquid

1-Butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) ionic liquid (IL) is considered for CO2 capturing in a typical absorption/stripper process. The use of ionic liquids is considered to be cost-effective because it requires less energy for solvent recovery compared to other conventional processes. A mathematical model was developed for the process based on Peng-Robinson (PR) equation of state (EoS). The model was validated with experimental data for CO2 solubility in [BMIM][BF4]. The model is utilized to study the sorbent effect and energy demand for selected operating pressure at specific CO2 capturing rates. The energy demand is expressed by the vapor-liquid equilibrium temperature necessary to remove the captured CO2 from the spent solvent in the regeneration step. It is found that low recovery temperature can be achieved at specific pressure combination for the absorber/stripper units. In fact, the temperature requirement is less than that required by the typical monoethanolamine (MEA) solvent. The effect of the CO2 loading in the sorbent stream on the process performance is also examined.

Equilibrium Solubility of CO2 in Aqueous Mixtures of DEA and AEEA

The present communication presents the new experimental CO2 solubility data in an aqueous mixture of diethanolamine (DEA) and (2-aminoethyl)ethanolamine (AEEA) at CO2 concentrations in the inlet gas stream from (10.13 to 20.27) kPa and temperatures from (303.14 to 333.14) K. The aqueous (DEA + AEEA) mixtures of total concentrations were chosen from (0.92 to 3.22) mol·kg–1, and the mole fraction of AEEA in total amine was varied from 0.02 to 0.20. The findings point that the CO2 solubility in a fixed total concentration of amine mixture becomes more at a higher AEEA mole fraction in total amine with a constant temperature and CO2 concentration in the inlet gas stream. The CO2 solubility in the amine mixture falls with the rise in temperature but rises with an increase in CO2 concentration in the inlet gas stream. The highest amount of CO2 solubility in (DEA + AEEA) mixtures was observed as 0.74 mol CO2/mol absorbent with AEEA mole fraction in total amine of 0.2 at a 1.84 mol·kg–1 total concentration of ami...

Measurements and predictions of density and carbon dioxide solubility in binary mixtures of ethanol and n-decane

The solubility of carbon dioxide (CO2) in binary mixtures of ethanol and n-decane has been measured using an in-house developed pressure-volume-temperature (PVT) apparatus at pressures up to 6MPa and two different temperatures (303.2 and 323.2K). Three different binary mixtures of ethanol and n-decane were prepared, and the densities of the prepared mixtures were measured over the studied pressure and temperature ranges. The experimental data of CO2 solubility in the prepared mixtures and their saturated liquid densities were then reported at each temperature and pressure. The solubility data indicated that the gas solubility reduced as the ethanol mole fraction in the liquid mixture increased. The dissolution of CO2 in the liquid mixtures resulted in the increase in the saturated liquid densities. The impact of gas dissolution on the saturated liquid densities was more pronounced at the lower temperature and lower ethanol compositions. The experimental solubility and density data were compared with the results of two cubic equations of state (EOSs), Soave–Redlich–Kwong (SRK) and Peng–Robinson (PR). The modeling results demonstrated that both EOSs could predict the solubility data well, while the saturated liquid densities calculated with the PR EOS were much better than those predicted with the SRK EOS.

Density and volumetric expansion of carbon dioxide-expanded canola oil and its blend with fully-hydrogenated canola oil

Physical properties of lipids in equilibrium with high pressure carbon dioxide are influenced by CO2 solubility in the liquid lipid phase, which is a strong function of temperature and pressure. The experimental data of CO2 solubility in canola oil at 40 and 70°C and its blend with fully-hydrogenated canola oil (FHCO) (30wt%) at 70°C up to 25MPa were correlated using Peng–Robinson and modified Soave–Redlich–Kwong equations of state with quadratic and Panagiotopoulos–Reid mixing rules. The relative volumetric expansion of canola oil at 40°C up to 20MPa and 70°C up to 25MPa and its blend with FHCO (30wt%) at 70°C up to 25MPa in equilibrium with CO2 was 41, 46, and 43%, respectively. The densities of canola oil at 40, 55, and 70°C and its blend with FHCO at 70°C in equilibrium with CO2 were measured up to 30MPa and increased by 4.7, 4.3, 3.5, and 3.6% of its value at atmospheric pressure, respectively. The density of CO2-expanded lipids increased with pressure and decreased with temperature. Physical properties of CO2-saturated lipids are important for designing high pressure processes and especially here for better understanding of enzymatic interesterification of canola oil and FHCO using supercritical CO2, since these physical properties influence the reaction rates due to changes in mass transfer.

State-of-the-Art of CO2Capture with Ionic Liquids

Economical and environmental aspects are the main motivation for research on energy efficient processes and the search for environment friendly materials for CO2 capture. Currently, CO2 capture is dominated by amine-based (e.g., monoethanolamine) technologies, which are very energy intensive and less attractive from an environmental point of view due to emissions of the used volatile solvent components. Ionic liquids have been proposed as a promising alternative to the conventional volatile solvents, because of their low volatility and other interesting properties. This remarkable interest has led to a rapid growth of literature on this specific subject. The aim of the present review paper is to provide a detailed overview of the achievements and difficulties that has been encountered in finding a suitable ionic liquid for CO2 capture from flue-gas streams. A major part of this review includes an overview of the experimental data of CO2 solubility, selectivity, and diffusivity in different ionic liquids. ...