Hybrid Solvent Research Articles

Integration study of a hybrid solvent MEA-Methanol for post combustion carbon dioxide capture in packed bed absorption and regeneration columns

Abstract The present work reported tests of a new solvent 30 wt% MEA-Methanol compared to aqueous 30 wt% MEA solvent in a pilot-plant test bed, which comprises the complete absorption/desorption. The two solvents were studied in the same way in the test bed and detailed results were reported for both solvents. The measurements were carried out at a constant CO2 removal rate of 90% by an adjustment of the regeneration energy in the desorber for systematically varied L/G ratios, flue gas flow rate and absorber height. Results from these studies indicated that MEA-Methanol solvent had a faster CO2 absorption rate and a lower regeneration energy consumption compared to aqueous MEA solvent. Regeneration heat duty (Qreg) of MEA-Methanol solvent at optimum operating conditions was obviously lower than that of aqueous MEA solvent (3.22 MJ/kg CO2 and 4.04 MJ/kg CO2, respectively), which showed that MEA-Methanol had a potential to replace aqueous MEA solvent in industrial CO2 pilot plant.

Mass Transfer Behaviour in Hybrid Solvent Oil Recovery Processes

The mechanisms of mass transfer in thermal solvent enhanced oil recovery processes and the influence of grid size in the numerical simulation of these processes is not well understood [1, 2]. The literature has indicated that, experimentally, solvent fronts progress more rapidly that what can be predicted using current approximations [3]. It has also been shown that under certain modelling conditions with coarser grid meshes, the influence of numerical errors can be substantial. The equations that govern thermal/solvent multiphase flow through porous media are extremely complex and it is very difficult to decouple the contribution of the mass transfer mechanisms from the thermal effects. This paper was written to increase the understanding of the mass transfer mechanisms in hybrid thermal solvent recovery processes through sensitivity study using a numerical solution of the linear one dimensional advection diffusion/dispersion (ADD) equation. This equation was modeled using finite difference methods. The effects of grid size were examined to verify the use of this method, and the results were then used to examine the sensitivity of the equation to the parameters that govern the mass transfer mechanisms (advection velocity, diffusion and dispersion coefficients).In particular, a range of values for diffusion and dispersion coefficients were selected for the sensitivity study, and one advection velocity. These values were then used to numerically solve the ADD equation to assess the impact of each mechanism (advection, diffusion and dispersion) and their contribution to the movement of the solvent front. The parameters chosen for this study were based on values obtained from the literature for advection velocity, diffusion and dispersion coefficients consistent with a gravity drainage thermal/solvent oil recovery process. This sensitivity study has indicated that all three mechanisms (advection, diffusion and dispersion) must be included to have the solvent front progress at rates that are consistent with experimental solvent front advance rates published in the literature to date [1]. This result suggests that diffusion alone cannot account for the movement of the solvent front within the ranges of values that have been studied.

Experimental study of a hybrid solvent MEA-Methanol for post-combustion CO 2 absorption in an absorber packed with three different packing: Sulzer BX500, Mellapale Y500, Pall rings 16 × 16

Abstract Effects of different operating conditions on the CO 2 capture and mass transfer performance of the absorption of CO 2 into a hybrid solvent MEA-Methanol were studied in a pilot-plant absorber packed with three different packing consist of Sulzer BX500, Mellapale Y500 and Pall rings 16 × 16. The results showed that the structured packing had an obvious advantage in the mass transfer performance. And Sulzer BX500 was better than Mellapale Y500 for it had a more uniform gas–liquid distribution on the packing surface. In addition, CO 2 lean loading, lean solvent temperature, lean solvent flow rate and flue gas flow rate all had great effects on the absorption performance of the MEA-Methanol absorption system.

Thermophysical Properties of Aqueous 1-Butyl-3-Methylimidazolium Acetate [BMIM] [AC] + Monoethanolamine (MEA) Hybrid as a Solvent for CO2 Capture

In this study, ionic liquid-amine ([BMIM] [AC]+MEA) hybrid solvent was prepared for CO2 capture and its properties were investigated. The hybrid solvent was prepared at different ratios of ionic liquid-amine concentration. The properties such as density, viscosity and refractive index of aqueous ionic liquid-amine ([BMIM][AC]+MEA) hybrid solvent were investigated at different ionic liquid to amine mass ratios of 0.33, 0.6, 1, 1.33 and 1.67 and ionic liquid-amine hybrid mass fraction(w1+w2) % in the aqueous solution of (0.1+0.3), (0.2+0.3), (0.3+0.3), (0.4+0.3), (0.5+0.3) wt.% respectively. The temperature used for each sample investigation was varied from 298.15-313.15K at the intervals of 5 k. From the investigation conducted, it was demonstrated that increasing the concentration of ionic liquids in the aqueous ionic liquid-amine hybrid solvent increased the density, viscosity as well as refractive index of the hybrid solvent. The temperature has a reverse effect on these properties though the effect of temperature on viscosity at a higher temperature greater than 340 k is less dependent on the concentration of the hybrid solvent. It was also observed that small change in temperature has a negligible effect on the density of hybrid solvent.

High Pressure Rheology and Viscosity of Monoethanolamine with n-Methyl-2-Pyrrolidone and Water Hybrid Solvent

In this work, the rheology of a solvent which consisted of monoethanolamine (MEA) as well as water and n-methyl-2-pyrrolidone (NMP) (weight ratio 20:40:40) was studied at gauge pressure up to 5 MPa and temperature range from 303.15 to 333.15 K. The flow chart showed positive linear relationship between shear stress and shear rate for the solvent at all temperature and pressure conditions tested. This trend was consistent with the behaviour of a Newtonian fluid. The dynamic viscosity of MEA-NMP hybrid solvent at temperature from 303.15 to 333.15 K and gauge pressure from (0.1 to 5) MPa was calculated from the rheology data measured.

Rational Formulation Design and Commercial Application of a New Hybrid Solvent for Selectively Removing H2S and Organosulfurs from Sour Natural Gas

Based on the investigation on nonbonded interactions between solvent and organosulfur molecules, the reaction kinetics of carbonyl sulfide (COS) with chemical solvents in aqueous solutions, and experimental validation, a hybrid solvent (named UDS-2) was designed to simultaneously remove H2S and organosulfurs from sour natural gas at high removal efficiency. The solvent components, which could enhance physical and chemical absorption of methyl mercaptan and COS, were screened using quantum chemistry method coupled with kinetics analysis. The results show that the five-membered sulfur heterocyclic compound (SUL) exhibits significant advantage of physical solubility of methyl mercaptan and COS. Meanwhile, the cyclic amine (CA) with weak steric hindrance effect as well as moderate basicity could enhance chemical removal of COS. UDS-2 solvent was obtained by blending SUL and CA with N-methyldiethanolamine (MDEA) at optimal proportion, and the removal efficiencies for methyl mercaptan, COS, and total organosulf...

Studies on the effect of addition of piperazine and sulfolane into aqueous solution of N-methyldiethanolamine for CO2 capture and VLE modelling using eNRTL equation

In this work, new experimental vapour liquid equilibrium (VLE) data and modelling work of VLE of CO2 in piperazine (PZ) activated aqueous solutions of n-methyldiethylamine (MDEA) are presented. Besides, experimental VLE data of CO2 in a hybrid solvent, containing sulfolane as physical solvent along with aqueous (MDEA+PZ), have also been reported over the temperature range of 308–328K and CO2 partial pressure range of 1–1400kPa. The concentrations of MDEA in the aqueous solutions are 22–28mass% and also 42–48mass%. PZ is used as a rate activator within a concentration range of 2–8mass%. The total amine concentration in the aqueous solutions of (MDEA+PZ) has been kept within 30mass% and also 50mass%, while for the hybrid solvent the concentration of sulfolane has been maintained at 10mass% along with total 50mass% (MDEA+PZ). Electrolyte non random-two liquid (eNRTL) theory has been used to model the VLE. It has been found that there is a good agreement between the experimental and model results of CO2 solubility in PZ activated MDEA solutions. The CO2 cycle capacity is calculated considering a set of lower and higher CO2 partial pressures corresponding to lower (lean solvent) and higher (rich solvent) equilibrium CO2 loadings. For the sulfolane based hybrid solvent, it has been observed that the CO2 cyclic capacity of the solvent decreases with the lower lean-rich partial pressure range of 10–100kPa, but increases at higher partial pressure ranges of 100–1000kPa at 323K. PZ mass% in the hybrid solvent has also been found to have a positive effect on the CO2 cyclic capacity.

Performance of a hybrid solvent of amino acid and ionic liquid for CO2 capture

Advanced solvents are under development to reduce the energy consumption for CO2 capture from the coal-fired power plant. In this work, an amino acid, sodium glycinate (SG), and an ionic liquid, [Bmim][BF4], were blended to be used as solvent for CO2 capture. The parametric tests such as blending mole ratio, temperature, CO2 partial pressure and oxygen concentration were investigated. Results revealed the highest CO2 absorption rate was achieved when the blending mole ratio of SG and [Bmim][BF4] was 4:1. Compared with the pure SG solution, the CO2 absorption rate into those blends was 40% higher than that into the pure SG solution under the same tested conditions. The high temperature and CO2 partial pressure facilitated the CO2 absorption. Overall, the blends of SG and [Bmim][BF4] possessing a high CO2 absorption rate, good anti-oxidation ability, and good regeneration efficiency may be an alternative of the MEA solution for CO2 capture.

Free Energy Landscapes of Alanine Oligopeptides in Rigid-Body and Hybrid Water Models.

Replica exchange molecular dynamics is used to study the effect of different rigid-body (mTIP3P, TIP4P, SPC/E) and hybrid (H1.56, H3.00) water models on the conformational free energy landscape of the alanine oligopeptides (acAnme and acA5nme), in conjunction with the CHARMM22 force field. The free energy landscape is mapped out as a function of the Ramachandran angles. In addition, various secondary structure metrics, solvation shell properties, and the number of peptide-solvent hydrogen bonds are monitored. Alanine dipeptide is found to have similar free energy landscapes in different solvent models, an insensitivity which may be due to the absence of possibilities for forming i-(i + 4) or i-(i + 3) intrapeptide hydrogen bonds. The pentapeptide, acA5nme, where there are three intrapeptide backbone hydrogen bonds, shows a conformational free energy landscape with a much greater degree of sensitivity to the choice of solvent model, though the three rigid-body water models differ only quantitatively. The pentapeptide prefers nonhelical, non-native PPII and β-sheet populations as the solvent is changed from SPC/E to the less tetrahedral liquid (H1.56) to an LJ-like liquid (H3.00). The pentapeptide conformational order metrics indicate a preference for open, solvent-exposed, non-native structures in hybrid solvent models at all temperatures of study. The possible correlations between the properties of solvent models and secondary structure preferences of alanine oligopeptides are discussed, and the competition between intrapeptide, peptide-solvent, and solvent-solvent hydrogen bonding is shown to be crucial in the relative free energies of different conformers.

CO2 Solubility in Hybrid Solvents Containing 1-Butyl-3-methylimidazolium Tetrafluoroborate and Mixtures of Alkanolamines

To reduce the rate of climate change, feasible and energy-efficient solutions need to be found to capture CO2 at low pressure from flue gas emitted by various industries and energy sectors worldwide. The use of solvents to selectively absorb CO2 is a promising option for CO2 capture. This research investigated the solubility of CO2 in hybrid solvents containing the 1-butyl-3-methyl imidazolium tetrafluoroborate [bmim][BF4] ionic liquid with mixtures of up to three alkanolamine solvents, namely monoethanolamine (MEA), diethanolamine (DEA), and methyl-diethanolamine (MDEA). Gravimetric analysis was used to measure equilibrium CO2 solubility in the hybrid solvents containing various compositions of the above components at CO2 partial pressures of 0.05 MPa to 1.5 MPa and temperatures of 303.15 K to 323.15 K. CO2 solubility in these solvents was benchmarked against pure ionic liquids, as well as conventional alkanolamine solvents, and modeled using the Posey–Tapperson–Rochelle model for the alkanolamines prese...

ChemInform Abstract: Highly Selective Perfluoroalkylation of Unsaturated Molecules Upon Photoirradiation in BTF as an Organic/Fluorous Hybrid Solvent

AbstractReview: 74 refs.

Experimental analyses of mass transfer and heat transfer of post-combustion CO2 absorption using hybrid solvent MEA–MeOH in an absorber

• Mass transfer of MEA–MeOH was comprehensively investigated. • The K G a v of MEA–MeOH is higher than that of MEA–H 2 O. • MeOH is vulnerable to evaporate and should be operated at a low temperature. • Optimizing operating conditions can reduce solvent evaporation. The performance of CO 2 absorption into a hybrid solvent such as monoethanolamine (MEA) in methanol (MeOH) was experimentally investigated in a lab-scale absorber packed with Sulzer DX-type structured packing, and compared with that of aqueous MEA solution. The experiments were performed at various key operating conditions over a MEA concentration range of 2.5–5.0 kmol/m 3 , a CO 2 lean loading range of 0–0.373 mol/mol, a liquid flow rate range of 2.92–16.09 m 3 /m 2 h, an inert gas flow rate range of 24.37–63.54 kmol/m 2 h, a CO 2 partial pressure range of 6.7–13.8 kPa, and an inlet liquid temperature of 10 °C. The absorption performance was presented in terms of the overall gas phase mass transfer coefficient ( K G a v ), CO 2 concentration and system temperature profiles along the height of the absorber, and the system temperatures at the bottom and the top of the absorber, T bot and T top , respectively. It was found that the K G a v for MEA–MeOH was higher than that of MEA–H 2 O. In addition, the experimental results showed that key operating parameters such as MEA concentration, CO 2 loading, liquid flow rate and inert gas flow rate have large effect on the performance of CO 2 absorption into the MEA–MeOH.

Thermodynamic Modeling and Assessment of Ionic Liquid-Based CO2 Capture Processes

Ionic liquid (IL)–amine hybrid solvents have been experimentally proved to be effective for CO2 capture. This Article provided rigorous thermodynamic models, process simulation, and cost estimation of a potential design of IL-based CO2 capture processes. Three ILs ([Bmim][BF4], [Bmim][DCA], and [Bpy][BF4]) were investigated to blend with MEA aqueous solution. The physicochemical properties of the ILs were predicted by several temperature-dependent correlations. Phase equilibria were modeled based on Henry’s law and NRTL equation, and the calculated values were in good agreement with the experimental data. The simulation results show that the [Bpy][BF4]–MEA process can save about 15% regeneration heat duty as compared to the conventional MEA process, which is attributed to the reduction of sensible and latent heat. Moreover, a modified [Bpy][BF4]–MEA process via adding intercooling and lean vapor recompression presents 12% and 13.5% reduction in overall equivalent energy penalty and capture cost as compare...

Screening tests of new hybrid solvents for the post-combustion CO2 capture processby chemical absorption

This study focused on the screening of new hybrid solvents (mixture of a chemical (usually an amine) and a physical (ether, alcohol, etc.) solvent) for the post-combustion CO2 capture process by chemical absorption. Such scrubbing solutions aim at combining the advantages of the two components, namely: a low regeneration energy and a high absorption capacity of the physical solvent at intermediate CO2 partial pressures, a better absorption performances of the chemical solvent at low CO2 partial pressures and also high absorption kinetics due to chemical reactions with CO2. The innovative aspect of our approach was based on the use of acetals as physical components of the hybrid solvent. The purpose of our study was to characterize and compare these new hybrid solvents in terms of absorption and regeneration performances using two types of screening tests. Different blended solutions (composed of a conventional amine such as monoethanolamine (MEA), diethanolamine (DEA), 2-amino-2-methyl-1-propanol (AMP)) and an acetal compound such as 2,5,7,10-tetraoxaundecane (TOU) were tested. Regarding the absorption performances, a double stirred cell reactor was used to compare the absorption efficiencies of the solvents at 298 K. It was observed that the addition of the acetal compound improves significantly the absorption efficiencies, especially at the beginning of the batch absorption test, namely at low CO2 loadings of the solution. Meanwhile, regeneration tests were performed using a regeneration cell allowing to compare the regeneration efficiency of the solvents at fixed heating power (600 W). The higher cyclic capacities and better regeneration efficiencies with acetals base solvents were also highlighted. Globally, this work confirms through this first step that new hybrid solvents, composed of amine(s) and acetal, could be a very promising alternative to classical solvents.

Finite domain simulations with adaptive boundaries: Accurate potentials and nonequilibrium movesets

We extend the theory of hybrid explicit/implicit solvent models to include an explicit domain that grows and shrinks in response to a solute's evolving configuration. The goal of this model is to provide an appropriate but not excessive amount of solvent detail, and the inclusion of an adjustable boundary provides a significant computational advantage for solutes that explore a range of configurations. In addition to the theoretical development, a successful implementation of this method requires (1) an efficient moveset that propagates the boundary as a new coordinate of the system, and (2) an accurate continuum solvent model with parameters that are transferable to an explicit domain of any size. We address these challenges and develop boundary updates using Monte Carlo moves biased by nonequilibrium paths. We obtain the desired level of accuracy using a "decoupling interface" that we have previously shown to remove boundary artifacts common to hybrid solvent models. Using an uncharged, coarse-grained solvent model, we then study the efficiency of nonequilibrium paths that a simulation takes by quantifying the dissipation. In the spirit of optimization, we study this quantity over a range of simulation parameters.

Enhanced CO2 Capture in Binary Mixtures of 1-Alkyl-3-methylimidazolium Tricyanomethanide Ionic Liquids with Water

Absorption of carbon dioxide and water in 1-butyl-3-methylimidazoliun tricyanomethanide ([C4C1im][TCM]) and 1-octyl-3-methylimidazolium tricyanomethanide ([C8C1im][TCM]) ionic liquids (ILs) was systematically investigated for the first time as a function of the H2O content by means of a gravimetric system together with in-situ Raman spectroscopy, excess molar volume (V(E)), and viscosity deviation measurements. Although CO2 absorption was marginally affected by water at low H2O molar fractions for both ILs, an increase of the H2O content resulted in a marked enhancement of both the CO2 solubility (ca. 4-fold) and diffusivity (ca. 10-fold) in the binary [C(n)C1im][TCM]/H2O systems, in contrast to the weak and/or detrimental influence of water in most physically and chemically CO2-absorbing ILs. In-situ Raman spectroscopy on the IL/CO2 systems verified that CO2 is physically absorbed in the dry ILs with no significant effect on their structural organization. A pronounced variation of distinct tricyanomethanide Raman modes was disclosed in the [C(n)C1im][TCM]/H2O mixtures, attesting to the gradual disruption of the anion-cation coupling by the hydrogen-bonded water molecules to the [TCM](-) anions, in accordance with the positive excess molar volumes and negative viscosity deviations for the binary systems. Most importantly, CO2 absorption in the ILs/H2O mixtures at high water concentrations revealed that the [TCM](-) Raman modes tend to restore their original state for the heavily hydrated ILs, in qualitative agreement with the intriguing nonmonotonous transients of CO2 absorption kinetics unveiled by the gravimetric measurements for the hybrid solvents. A molecular exchange mechanism between CO2 in the gas phase and H2O in the liquid phase was thereby proposed to explain the enhanced CO2 absorption in the hybrid [C(n)C1im][TCM]//H2O solvents based on the subtle competition between the TCM-H2O and TCM-CO2 interactions, which renders these ILs very promising for CO2 separation applications.

Highly Selective Perfluoroalkylation of Unsaturated Molecules upon Photoirradiation in BTF as an Organic/Fluorous Hybrid Solvent

Benzotrifluoride (BTF), an eco-friendly solvent, can dissolve many organic and fluorous molecules because of the organic and fluorous motifs in its structure. Using BTF as solvent, we have developed a series of reactions for perfluoroalkylation of various unsaturated compounds upon photoirradiation with a Xe lamp through Pyrex. For example, alkynes, allenes, vinylcyclopropanes, isocyanides, diynes, dienes, and enynes successfully undergo regioselective perfluoroalkyliodination, perfluoroalkylselenation, and perfluoroalkyltelluration in BTF. In addition, the present photoinitiation procedure can be applied to trifluoromethylation

Determining the Performance of an Efficient Nonaqueous CO2 Capture Process at Desorption Temperatures below 373 K

Efficient CO2 capture by chemical absorption is currently gaining interests for the control greenhouse gas emissions. In this work, a nonaqueous process was developed to regenerate CO2 below 373 K by removing methanol first after the hybrid solvent of monoethanolamine (MEA) and methanol had absorbed CO2. A model was accordingly developed to analyze the performance of the desorption process. Experiments were performed to determine the missing reaction kinetics of nonaqueous solvent regeneration of CO2 to help develop the model. The predicted gas concentration, axial velocity, energy consumption, and desorption efficiency agreed well with the stripper experimental data. A parametric analysis was conducted to investigate the effects of temperature, pressure, lean solvent loading, gas/liquid ratio, packing, and internals on the energy consumption and desorption efficiency. All analyses were performed under three defined desorption conditions: N2, methanol vapor, and steam as purge gases. Major energy savings ...

Absorption of SO2 in aqueous solutions of mixed hydroxylammonium dicarboxylate ionic liquids

Three new hydroxylammonium dicarboxylate ionic liquids (ILs) dimethylethanolammonium dimalonate ([DMEAH][dimalonate]), dimethylethanolammonium dimalate ([DMEAH][dimalate]) and dimethylethanolammonium diglutarate ([DMEAH][diglutarate]) were synthesized and mixed with free DMEA and water to form novel hybrid solvents for SO2 absorption. The mixed absorbents exhibited low viscosity in the range of 6–13mPas at 313.2K, favoring the transfer performance of SO2 absorption. Significantly, they reached SO2 absorption equilibrium in less than 50s, and their absorption capacities were as high as 0.1–0.6mol SO2 per mol IL at 313.2K and 0.004bar SO2 partial pressure. SO2 solubility increased with increasing DMEA/IL molar ratio, whereas desorption efficiency decreased. pH significantly affected SO2 absorption and desorption performance in the mixed absorbents. The optimal pH for desulfurization was approximately 4.5–5.5, a compromise between absorption and desorption ability. Compared with pure task-specific ILs for SO2 absorption, which are too expensive and viscous for flue gas desulfurization, the mixed absorbents described in this study have more practical applications.

Effect of PEO on the Hydrophilicity of PLLA Ultrafine Fibers

The Polyethylene oxide (PEO) / Poly (L-lactic acid) (PLLA) ultrafine blend fibers have been prepared by electrospinning. The hybrid solvent of trichloromethane and ethanol was found to be the co-solvent for electrospinning. The PEO/PLLA blend solutions in various ratios were studied for electrospinning into ultrafine fibers. The morphology of the fibers was shown by scanning electron microscope (SEM). The hydrophilicity of fiber samples was characterized by determining their water contact angle. The spun ultrafine fibers are expected to be used in the native extracellular matrix for tissue engineering.