Law Constant Of CO2 Research Articles

CO2 solubility and absorption rate analysis of a mixed poly(oxymethylene) dimethyl ethers (PODE3–5) solution

Efficient and economical carbon capture is critical to counteract the diverse problems of global warming. In this work, the solubility of carbon dioxide (CO2) in different poly(oxymethylene) dimethyl ethers (PODE) solutions was experimentally investigated at temperatures from 278.15 to 308.15 K and pressures up to 1.2 MPa. The Henry's law constants of CO2 in the PODE system were determined and compared with other types of physical absorbents, which revealed PODE3–5 has great CO2 absorption ability in terms of molar and mass fraction. Meanwhile, the initial absorption rate of the physical absorption process of PODE3–5 was calculated and compared with commercially available absorbents using a gas absorption rate relationship. It was shown that the absorption rate of PODE3–5 in the CO2 absorption process is faster than that of other commercial absorbents. The CO2 solubility data of PODE3–5 were also correlated using the Jou-Mather model and the perturbed-chain statistical association fluid theory (PC-SAFT) equation of state model, and the recycling performance of the PODE3–5 absorbent was tested.

Measuring and modeling the solubility of carbon dioxide in protic ionic liquids

The solubility of carbon dioxide (CO2) in three protic ionic liquids, namely N-Ethylmorpholine acetate ([NEMH][Ac]), N-Ethylmorpholine propionate ([NEMH][Pro]), and Triethylamine propionate ([TEAH][Pro]), was measured at temperatures from 298.15 to 338.15 K and pressures up to about 900 kPa. The solubility data were fitted by Pitzer's model and Soave-Redlich-Kwong (SRK) cubic equation of state. In the range of experimental uncertainty, both models can well correlate solubility data. Henry's law constants of CO2 in these three protic ionic liquids at zero pressure were estimated from the solubility data, and the partial molar Gibbs free energy, partial molar enthalpy, and partial molar entropy at infinite dilution were calculated.

Solubility of CO2 in nonaqueous system of 2-(butylamino)ethanol with 2-butoxyethanol: Experimental data and model representation

Nonaqueous amine-based system is an attractive solution to overcome high-energy-intensive CO2 capture process using the conventional aqueous amines. Advanced nonaqueous absorbent of 2-(butylamino)ethanol (BAE) with 2-butoxyethanol (2-BE) has been recently proposed for low-energy-consumption CO2 capture. In this work, Henry’s law constants of CO2 in the BAE/2-BE blend were obtained by N2O/CO2 analogy, and correlated in the temperature range of (283–333) K. Vapor-liquid equilibrium (VLE) data for the BAE + CO2 + 2-BE system at 65.4% (mass) BAE were also determined in a stirred equilibrium cell at temperatures of (313–393) K and CO2 partial pressures up to 275 kPa. A single apparent equilibrium constant KCO2,app was proposed for this system and correlated as a function of temperature, carbonated degree of amine and CO2 loading. Solubility data were well represented by the modified Kent-Eisenberg model with an average absolute relative deviation (AARD) of 13%.

Prediction of Henry's law constants of CO2 in imidazole ionic liquids using machine learning methods based on empirical descriptors

In this study, a total of 160 experimental data points of Henry's law constant of CO2 in 32 imidazole ionic liquids (ILs) were collected, with the temperatures range from 283 to 350 K. Herein intuitive and explanatory descriptors related to Henry's law constant (HLC) were suggested from the 2D structural features of the ILs according to experimental experience and laws. Temperature was used as another variable due to its significant effect on Henry's law constant. Three machine learning methods were used to construct models to fast predict the HLC based on suggested descriptors. Multi-layer Perceptrowas mainly used to build the model and compared with the results of Random forest and Multiple Linear Regression after investigating the outliers and variable selection. In addition, if only one data point was left at a similar temperature and the reduced dataset was also used to build models in the same procedure, the results were not as good as those of the full dataset but still satisfactory.

Adsorption separation of CF4, O2, CO2, and COF2 from an excimer gas mixture

The use of adsorbents is explored as an option for the removal of trace impurities of CO2, CF4, COF2, and O2 from F2, Kr, and Ne for applications in excimer lasers. Due to the incompatibility of many adsorbents to F2 and HF, aluminas and polymeric adsorbents were selected as potentially compatible materials. To determine the adsorption potential of these adsorbents in the low concentration region, the concentration pulse chromatographic technique was chosen to determine the Henry’s Law constants of CO2, CF4, and O2 gases with three polymeric adsorbents (HayeSep Q, HayeSep B, and Fluorinated DVB) and two aluminas (AA-300, and Alumina A). The results were plotted and compared on van’t Hoff plots (the natural logarithm of Henry’s Law constants as a function of inverse absolute temperature) with the heat of adsorption values being calculated from the lines of best fit for all gases and adsorbents tested in this study. Due to the large energies required to operate the excimer lasers, a cryo-cooler was determined to be feasible to precool the feed stream before separation, which increases the adsorption capacity and the compatibility of the adsorbents to F2 and HF. The van’t Hoff plots were extrapolated to colder temperatures to determine the Henry’s Law constants to analyze the potential of using the cryo-cooler. From this study, it was determined that HayeSep Q was the best polymeric adsorbent with significant adsorption of CO2 at temperatures below −50 °C while being the best performing CF4 adsorbent. AA-300 was the best performing alumina in this study while having significant adsorption of CF4 at temperatures below −135 °C. However, from a compatibility standpoint, both of these materials need to be tested to determine their robustness in the presence of F2 and HF at room and reduced temperatures.

Thermodynamic modeling and energy analysis of a polyamine-based water-lean solvent for CO2 capture

Amine-based water-lean solvents are considered to be promising energy-saving alternatives to existing aqueous amine solvents for CO2 capture. Herein, we propose water-lean solvents comprising 3,3′-iminobis(N,N-dimethylpropylamine) (60 wt%), water (10–18 wt%), and a non-amine chemical (balance), probe the solubility of CO2 therein, and perform the energy demand analysis using an Aspen Plus®-based simulator. For CO2 solubility modeling, the e-NRTL model and Redlich-Kwong state equation were incorporated with the equilibrium reaction model proposed by previous researchers, and the Henry’s law constant of CO2 was estimated using molecular dynamics simulation as it is difficult to measure experimentally. Experimental data acquired using an equilibrium cell and 13C/1H NMR were used to regress the equilibrium reaction model. The minimum thermal energy demand under desorber pressures of 303 and 505 kPa was calculated to be as low as 1.99 and 1.95 GJ t-CO2−1, respectively, which supports the suitability of the developed WLSs for post-combustion CO2 capture.

Solubility of CO2 in aqueous 2‑amino‑1, 3‑propanediol (Serinol) at elevated pressures

In this work, aqueous 2‑amino‑1, 3‑propanediol solution (serinol) was investigated as a potential solvent for CO2 capture from different gas streams. Prior to CO2 solubility experiments, a qualitative prediction technique was performed on serinol to ensure its potentiality as a CO2 capture solvent. This was done using COSMO-RS approach based on quantum chemistry calculations. Based on this approach, serinol showed good affinity towards hydrogen–bond donors which proved to be beneficial in developing intermolecular interaction between serinol and CO2. The solubility of CO2 in serinol was then investigated at serinol concentrations ranging from 1 M to 3 M, temperatures ranging from 313.15 K to 353.15 K and CO2 partial pressures ranging from 1034.31 kPa to 2068.43 kPa. The solubility of CO2 in serinol reached a highest value of 1.64 mol of CO2/mol of serinol when the serinol concentration was 1 M, at 313.15 K and 2068.43 kPa. Meanwhile, Henry's law constant of CO2 in serinol was calculated using N2O analogy at 313.15 K and 333.15 K for molar concentrations of 1 M and 3 M of serinol. Results showed that the physical solubility of CO2 in serinol increased as the temperature and the concentration of the solution decreased. The lowest value of Henry's law constant of CO2 was 599.4 kPa·m3·kmol−1, for 1 M of serinol at 313.15 K. Furthermore, the recyclability of 3 M of serinol was investigated at 313.15 K and partial pressures ranging from 1034.31 kPa to 2068.43 kPa. At 1034.31 kPa, the solubility of CO2 in 3 M of aqueous serinol after the 3rd regeneration cycles were reduced to 72.73%.

Prediction of Henry's law constant of CO2 in ionic liquids based on SEP and Sσ-profile molecular descriptors

Nowadays, greenhouse gas CO2 emissions have caused serious global warming problems. Unique properties of ionic liquids (ILs), such as negligible vapor pressure, good thermal and chemical stability, high gas dissolution capacity, etc., have made them highly promising in capturing CO2. Although researchers have done a lot of experimental work using ILs to capture CO2, time-consuming and high experimental economic costs have led to a strong interest in establishing predictive models. In this work, 297 experimental data points including 16 cations and 9 anions for 34 ILs are collected and the structures of cations and anions are optimized by quantum chemistry. Then the electrostatic potential surface area (SEP) and charge distribution area (Sσ-profile) descriptors are calculated and used to predict the Henry's law constant (HLC) of CO2 in ILs. Three new models, namely, the multiple linear regression (MLR), support vector machine (SVM), and extreme learning machine (ELM) are finally developed based on the above-calculated descriptors. Results show that the ELM model with AARD = 3.22% for the entire data set is the most valid and powerful one to predict the HLC of CO2.

Solubility of Carbon Dioxide in Poly(oxymethylene) Dimethyl Ethers

Experimental data on the solubility of carbon dioxide (CO2) in poly(oxymethylene) dimethyl ethers (CH3O(CH2O)nCH3, OMEn) are presented for OME2, OME3, and OME4. The total pressure was measured as a function of the liquid phase composition at 313.15 and 353.15 K for pressures up to 4.3 MPa in a high-pressure view-cell. Henry’s law constants of CO2 in OME2, OME3, and OME4 are determined. They are similar for all studied OME and depend strongly on the temperature. The experimental data are modeled by the original perturbed-chain statistical associating fluid theory equation of state. As a basis, pure component models for OME were developed based on literature data on the liquid density and vapor pressure. The solubility of CO2 in OME is successfully described using a group contribution scheme. The results show that OME are interesting candidates as physical absorbents for CO2.

The Role of Partial Atomic Charge Assignment Methods on the Computational Screening of Metal-Organic Frameworks for CO2 Capture under Humid Conditions

Molecular simulations were carried out to compare the results from two different partial charge assignment strategies: extended charge equilibration (EQeq), and density derived electrostatic and chemical (DDEC), by computing the Henry's law constants of CO2, H2O, and N2 for computation-ready, experimental (CoRE) MOFs. The Spearman's ranking correlation coefficient (SRCC) of the CO2/H2O selectivity rankings of MOFs with DDEC and EQeq charges based on the Henry's law constants showed that 8 out of the top 15 MOFs from screenings of MOFs with DDEC and EQeq charges were identical. We found that the most significant difference was observed in the adsorption energy for H2O molecules, which showed large contribution from electrostatic interactions in H2O adsorption energy, and for CO2 and N2 adsorption energies, van der Waals interaction energies played a major role.

Molecular simulation study of the CO2-N2O analogy

The validity of the CO2-N2O analogy concerning the Henry's law constant is investigated by molecular simulation of the solvents water, ethanol, as well as their mixtures. Molecular models for carbon dioxide (CO2) and for the solvents water and ethanol are taken from the literature. For nitrous oxide (N2O), two new molecular models are presented. They differ in their structure, but are both parametrized using pure component vapor-liquid equilibrium data. The models are used to study Henry's law constants of CO2 and N2O in pure water and pure ethanol over a wide range of temperatures. In the case of water, a slight adjustment in the water-solute interaction is necessary to achieve agreement with experimental data, whereas the gas solubilities in ethanol are predicted quantitatively without any adjustment. For mixed solvents containing both water and ethanol, the CO2-N2O analogy is found to be invalid, contradicting a widespread assumption.

Descriptive and predictive models for Henry’s law constant of CO2 in ionic liquids: A QSPR study

Associate surplus substances presence in natural gases like carbon dioxide (CO2) causes prominent problems in transporting and storage stages. Unique features of ionic liquids such as low vapor pressure, excellent thermal and chemical stability, high power of dissolution, etc., have made them as green solvents and organic solvents substitution in the separation processes, especially the separation of CO2. Although many experimental works have been done to determine the ability of ionic liquids in separation of CO2, expensive and time-consuming laboratory methods have led to a strong interest in the modeling methods. In this work, quantitative structure–property relationship (QSPR) models for predicting the Henry’s law constant (HLC) for CO2 dissolution in 32 ionic liquids have been developed. Chosen descriptors by genetic algorithm were used to develop two models by MLR and LS-SVM methods. The three-parameter model has been considered as the main model and a detailed physical interpretation has been mentioned for all parameters. Comparison of the predicted values of HLC with the experimental data, internal validation results and statistical parameters show that the proposed QSPR model by MLR and LS-SVM methods are reliable, predictive and stable; however the non-linear model is more powerful than the linear one.

Viscosities and Carbon Dioxide Solubilities of Guanidine Carbonate and Malic Acid-Based Eutectic Solvents

Carbon capture and storage (CCS) is one of the technologies needed to reduce anthropogenic emissions of CO2 in the atmosphere. Protic ionic liquids (PILs) are potential nonaqueous solvents that can combine the benefits of ionic liquids (ILs) and deep eutectic solvents (DESs) to make the carbon capture process more sustainable. In the present study, the viscosities of six eutectic-based solvents have been measured within a temperature range of 303.2–330.2 K and have been modeled using a Vogel–Fulcher–Tammann (VFT)-type equation. The results showed that guanidium malate-based eutectic solvents have significantly lower viscosities than most other deep eutectic solvents. Additionally, CO2 solubilities in three different guanidium-based eutectic solvents have been measured within a temperature range of 313.2–333.2 K and pressures of up to 200 kPa. Henry’s law constants of CO2 in pure solvents were obtained by modeling the solubility in mixed (aqueous) solvents. The values obtained for Henry’s law constants of ...

Simultaneous measurement of CO2 sorption and swelling of phosphate-based ionic liquid

The development of alternative CO2 capture solvents such as ionic liquids (ILs) and nanoparticle organic hybrid materials (NOHMs) have provided interesting options for CO2 capture. In this study, CO2 interactions with 1,3-dimethylimidazolium dimethylphosphate ([MMIM]DMP), 1-ethyl-3-methylimidazolium dimethylphosphate ([EMIM]DMP) and 1-ethyl-3-methylimidazolium diethylphosphate ([EMIM]DEP) that contain inorganic ester groups based on phosphate, were investigated using ATR FT-IR spectroscopy. CO2-induced swelling, CO2 diffusivity and CO2 capture capacity were simultaneously measured to identify CO2 capture mechanisms, kinetics and diffusion behaviors as a function of the alkyl chain length of the cation. Henry's law constants of CO2 were found to be in the range of 4–11 MPa, which is in agreement with those reported in other studies.

Solubilities of carbon dioxide in the eutectic mixture of levulinic acid (or furfuryl alcohol) and choline chloride

The solubilities of carbon dioxide (CO2) in the renewable deep eutectic solvents (DESs) containing levulinic acid (or furfuryl alcohol) and choline chloride were determined at temperatures (303.15, 313.15, 323.15, and 333.15)K and pressures up to 600.0kPa using an isochoric saturation method. The mole ratios of levulinic acid (or furfuryl alcohol) to choline chloride were fixed at 3:1, 4:1 and 5:1. Standard Gibbs free energy, dissolution enthalpy and dissolution entropy were calculated from Henry’s law constant of CO2 in the DESs. Results indicated that levulinic acid based DESs are more effective to capture CO2 than furfuryl alcohol based ones. The solubility of CO2 in the DESs increased with increasing mole ratio of levulinic acid (or furfuryl alcohol) to choline chloride as well as pressure and decreased with increasing temperature.

Absorption degree analysis on biogas separation with ionic liquid systems

For biogas upgrading, present work mainly focuses on either thermodynamics or mass transfer properties. A systematical study on these two aspects is important for developing a new biogas separation process. In this work, a new criterion “absorption degree”, which combines both thermodynamics and mass transfer properties, was proposed for the first time to comprehensively evaluate the absorption performance. Henry’s law constants of CO2 and CH4 in ionic liquids–polyethylene glycol dimethyl ethers mixtures were investigated. The liquid-side mass transfer coefficients (kL) were determined. The results indicate that IL–NHD mixtures exhibit not only a high CO2/CH4 selectivity, but also a fast kL for CO2 absorption. The [bmim][NO3]+NHD mixtures present a high absorption degree value for CO2 but a low value for CH4. For presenting a highest relative absorption degree value, the 50wt% [bmim][NO3]+50wt% NHD mixture is recommended for biogas upgrading.

Screening of ionic liquids for CO2 capture using the COSMO-SAC model

In this work, we develop a simple method that can be used to screen for the ionic liquid (IL) candidates for use in various CO2 capture processes. In particular, Henry׳s law constant, an important physical quantify determining the capacity and selectivity of CO2 absorption, is determined from the product of infinite dilution activity coefficient (IDAC) of a gas molecule in an IL and the fugacity of the gas in a hypothetical liquid state. The IDAC is calculated using the predictive COSMO-SAC activity coefficient model, where the interaction between the gas and the IL are determined through the screening charges on the molecular surfaces obtained from quantum mechanical solvation calculations. We have developed a simple model for the fugacity of 4 gas molecules, including CO2, CH4, N2 and H2, and examined the solubility, selectivity, and the temperature dependency of solubility. The predicted results for Henry׳s law constant of CO2 in ILs are in good agreement with experimental data (53 data points) over a wide range of temperatures (from 283K to 303K), with an average absolute relative deviation (ARD) of 17%. This method is used to screen for the best IL candidates for CO2 capture from a set of 2080 ILs combined from 65 cations and 32 anions. The computational time used for screening for this set of IL is less than 3min on a personal computer. Our results show that the COSMO-SAC model can be a powerful method for the design and screening of new ILs as a medium for CO2 capture.

Solubility of carbon dioxide, nitrous oxide and methane in ionic liquids at pressures close to atmospheric

The purpose of this work is to determine the solubility of greenhouse gases in different ionic liquids (ILs). Experimental values for the solubility of carbon dioxide, methane and nitrous oxide in ionic liquids are measured at different temperatures and at pressures close to atmospheric. Carbon dioxide is the most soluble gas studied with mole fraction solubility of the order of 10−2. Nitrous oxide is one order of magnitude less soluble than carbon dioxide, whereas methane is the least soluble gas. Finally, a group contribution method aimed at estimating the Henry's law constant of CO2 in ILs as a function of temperature was developed. Such a method makes it possible to predict the solubility of CO2 in ionic liquids when experimental data are unavailable.

CO2Absorption into Mixed Aqueous Solutions of 2-Amino-2-hydroxymethyl-1,3-propanediol and Piperazine

Solubility data of CO2 in aqueous mixtures of 2-amino-2-hydroxymethyl-1,3-propanediol (AHPD) and piperazine (Pz) were measured over a range of temperature from 288.15 to 333.15 K and for total amine concentrations up to 3.1 kmol·m−3. The CO2 partial pressure was kept within 0.21−2 637 kPa using a vapor−liquid equilibrium (VLE) apparatus based on a static-analytic method. The solubility of N2O in the Pz−AHPD aqueous solutions was also performed in order to determine, with the N2O analogy, the Henry’s law constant of CO2 in these solutions. The experimental data for the ternary system AHPD−CO2−H2O were correlated using a modified Pitzer’s thermodynamic model for the activity coefficients combined with the virial equation of state for representing the fugacity coefficients. The solubility of carbon dioxide in aqueous solutions of mixed amine (Pz + AHPD) was predicted by supposing that the parameters characterizing the single amine systems are essential for describing the quaternary system behavior.

Screening of ionic liquids to capture CO2 by COSMO‐RS and experiments

AbstractA screening method is proposed for the molecular design of ionic liquids (ILs) to capture carbon dioxide (CO2), which can reduce efficiently the necessary experimental efforts. The COSMO‐RS method is implemented to predict the Henry's law constants of CO2 in 408 ILs with various combinations of cations and anions. It is found by the screening that the ILs with the anion tris(pentafluoroethyl)trifluorophosphate ([FEP]) show improved capability to capture CO2, compared with other ILs reported in literature. Then, three [FEP]‐based ILs are chosen to perform the solubility measurements by the intelligent gravimetric analyzer (IGA 003, Hiden Analytical), with cations of 1‐hexyl‐3‐methylimidazolium ([hmim]), 1‐butyl‐1‐methylpyrrolidinium ([bmpyrr]), and S‐ethyl‐N,N,N′,N′‐tetramethylthiouronium ([ETT]) at 283.2, 298.2, and 323.2 K, up to the pressure of 1.8 MPa. The experimental data show that the solubility of CO2 in [hmim][FEP] is about 15% higher than that in 1‐hexyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide ([hmim][Tf2N]), which is in fair agreement with the screening results, indicating the method proposed in this work is reliable. © 2008 American Institute of Chemical Engineers AIChE J, 2008