The concept of eutectic solvents as a platform technology for a variety of applications including gas separation has become a popular approach. To date, the number of known deep eutectic solvents ...(DESs) is limited mainly to halide salts easily interacting with a hydrogen-bond donor (HBD) and resulting in the formation of a liquid phase. Actually, the DESs properties may be tuned by selecting the appropriate HBD, while the structure of the anion is not a decisive factor. However, the presence of other anions may be favorable for certain applications; therefore, expanding the range of deep eutectic solvents seems a relevant issue of chemistry and material science. In this study, we report the high absorption properties of the DES based on 1-butyl-3-methyl imidazolium methanesulfonate–urea toward ammonia. The structure features investigations have revealed the major contribution of C(2)-H to hydrogen bonding. To assess the possibility of selective separation, the solubility of ammonia and two acidic gases (H2S and CO2) in the absorbent has been measured. A superior gas sorption capacity was observed for ammonia, for which the Henry’s law constant was equal to 1.52 bar. The obtained results exceeded the solubility data reported in the literature for various ILs containing hydrogen-donating groups. The DESs demonstrated lower yet acceptable solubility toward hydrogen sulfide, whereas the solubility of CO2 was relatively poor. The thermostimulated desorption has demonstrated that the ability of gases to bind with DES molecules can be ranked as follows: NH3 > H2S > CO2. The physical sorption mechanism of ammonia, hydrogen sulfide, and carbon dioxide in the DES was proven by FTIR and thermal desorption analysis. The absorption was totally reversible, and the solubility of gases remains almost unchanged after three cycles.
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A mesoporous silica support was synthesized using the sol-gel method from trichlorosilane. There is a tendency for the specific surface area and the proportion of silica particles mesopores to ...increase during all stages of sol-gel synthesis. It has been shown that the insertion of hexane and toluene, as additional solvents, into the structure-forming polyethylene glycol, makes it possible to regulate the pore size and specific surface area of silica. Silica functionalization was carried out using SILP technology. The activities of the catalytic systems based on polymer and inorganic supports immobilized by imidazole-based ionic liquids during the trichlorosilane disproportionation reaction were compared. There is a tendency for the monosilane yield for catalytic systems based on an inorganic support to increase. We identified the most promising catalyst in terms of monosilane yield and proposed a bifunctional catalyst that exhibited activity in two parallel reactions: trichlorosilane disproportionation and silicon tetrachloride hydrogenation.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
Two new deep eutectic solvents (DESs) composed of urea (U) and salts of a choline family such as dimethyl-di(2-hydroxyethyl)-ammonium chloride Me2COH 2NCl and methyl-tri(2-hydroxyethyl)-ammonium ...chloride MeCOH 3NCl mixed in a 1:1 molar ratio were prepared. Their densities, viscosities, refractive indices, and properties related to the ammonia absorption were thoroughly investigated. We found that the obtained DESs show an absorption capacity of 2.078 and 2.632 molNH3·kg–1 DES for Me2COH 2NCl/U and MeCOH 3NCl/U, respectively, at 313.2 K and 101.3 kPa, which is approximately two times higher than for the choline chloride/urea (2:3) DES at the same conditions. Also, the obtained Henry’s law constants are of the same sequence; that is, they increase from MeCOH 3NCl/U to Me2COH 2NCl/U and finally to choline chloride/urea. The mentioned tendencies show good correlation with DES’s molar volume and its free volume, and also with the number of the CH2CH2OH substituents in a quaternary ammonium salt cation. This suggests that the gas capture occurs via the interactions (most likely H-bonding) between an NH3 molecule(s) and the hydroxyalkyl fragments. Indeed, the results of 1H NMR and FTIR spectroscopy confirm strong coupling between ammonia and hydroxyls leading to a distortion of the inherent DES structure. This finding agrees well with the fact that an NH3 dissolution process in the studied DESs is favored by an entropic contribution.
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•SILMs on bmim with different anions and novel ILs for acid gases separation.•Determination of wettability of fluorinated polymeric support by various ionic liquid.•CO2 (H2S)/CH4 and CO2 (H2S)/N2 ...permselective of developed SILMs and its stability.
The novel imidazolium salts based on bis(2-ethylhexyl) sulfosuccinate anion have been developed as ionic liquids (ILs) which can potentially be used as absorbents of acid gases. The transport of CO2, H2S, CH4 and N2 in a series of supported ionic liquid membranes (SILMs) with immobilized conventional (bmimPF6, bmimBF4, bmimTf2N) and novel ILs was investigated. The supported ionic liquid membrane containing 1-butyl-3-methylimidazolium bis(2-ethylhexyl) sulfosuccinate (bmimdoc) yielded a very high H2S solubility and, hence, H2S/N2 selectivity equal to 65. However, the permeability of acid gases through such a membrane had relatively low values varying in a range of 100–200Barrer, whereas permeability for SILMs impregnated by conventional ILs achieved 565Barrer. The most effective separation of CO2 was observed for SILMs impregnated by bmimBF4 predominantly owing to solubility component of permeability. In order to estimate the stability of SILMs, the polymeric support surface properties such as free surface energy, surface topology and roughness parameters were evaluated. Analysis of experimental data revealed that among the tested ILs, bmimBF4 immobilized in porous polymeric support was more resistant to losses and determined the higher stability of membranes.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
The present study continues the development and enhancement of a highly efficient unique hybrid technique-membrane-assisted gas absorption in designing the separation unit, which provides the ...improvement in mass-transfer of a target component during the ammonia capture process from a process loop of the Haber-Bosch technological route. In order to minimize the absorbent volume to membrane area ratio, the special separation cell was designed based on a combination of two types of hollow fiber membranes, dense gas separation membrane and porous pervaporation membrane. The separation performance tests were implemented under two sets of conditions, sweeping the bore (permeate) side of a cell with helium and hydrogen-nitrogen mix. For both cases, the membrane-assisted gas absorption cell demonstrated high separation efficiency, and the ammonia concentration in the permeate was never lower than 81 mol%; meanwhile, under the hydrogen-nitrogen bore sweep conditions, the ammonia concentration in the permeate reached 97.5 mol% in a single-step process. Nevertheless, there is a product purity-recovery rate trade-off, which is a typical issue for separation processes.
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•Solubility of CO2 and H2S in ILs containing bis(2-ethylhexyl) sulfosuccinate anion.•High uptake of acidic gases among the ILs, whose physically absorb them.•The impact of the cation’s protic nature ...on the thermodynamic properties of ILs.
Herein, we studied the absorption of H2S and CO2 in 1-methylimidazolium bis(2-ethylhexyl) sulfosuccinate (mimdoc) and 1-buthyl-3-methylimidazolium bis(2-ethylhexyl) sulfosuccinate (bmimdoc) at various temperatures and partial gas pressures. The choice of the doc anion was determined by the ability of bulky moieties along with the polar functional groups to enhance the solubility of acidic gases, as confirmed during the volumetric measurements of gases solubility. It was shown that the protic cation presence determines a significant reduction of the CO2 and H2S solubilities as well as the thermal stability of ILs. There were found that bmimdoc tends to have higher absorption capacity toward acidic gases compared with mimdoc. The solubility of hydrogen sulfide, characterized by the Henry’s Law constant, in bmimdoc and mimdoc turned out nearly 4–5 and 1.5–2 times higher than in conventional ionic liquids respectively.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Gas hydrate crystallization as an efficient method at natural gas processing.•Comparison of pressure-dropping and continuous gas hydrate crystallization.•The highest total recovery is 34.83 % under ...optimal conditions for continuous gas hydrate crystallization.
Gas hydrate crystallization is perspective and energy-efficient technology for gas mixtures processing, including natural gas. There were compared pressure-dropping and continuous gas hydrate crystallization methods for separation of gas mixture closed to natural gas. The studied mixture has been chosen similar to the natural gas composition: CH4 (75.68 mol.%) - С2H6 (7.41 mol.%) - C3H8 (4.53 mol.%) - н-C4H10 (2.47 mol.%) - CO2 (5.40 mol.%) - H2S (1.39 mol.%) - N2 (3.01 mol.%) - Xe (0.11 mol.%). Experiments were provided in the 4 L high pressure reactor, using water solution of SDS (0.20 wt.%). The experiment conditions were 280.15 K and pressure of 4.25 MPa. The components separation factors and recovery for two modes have been researched and compared for choosing more effective options. After comparing these characteristics, it was concluded that continuous process is more productive than pressure-dropping mode. At the stage cut (θ) of 0.9, the gas components total recovery (R) for the continuous mode have exceeded the total recovery for the pressure-dropping mode by 8.15 %, and at θ = 0.8, exceeded by 6.11 %. The recovery and separation factors have the highest values for H2S, C3H8, Xe in the continuous mode: 97.62 %, 94.90 %, 84.98 % and 8.7, 10.53, 6.36, respectively. Thus, the choosing of the more effective stage cut depends on the aim of the process: the highest purity or the largest recovery.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
The present paper deals with the complex study of CO
capture from combined heat power plant flue gases using the efficient technological design of a membrane cascade type of «Continuous Membrane ...Column» for binary gas mixture separation. In contrast to well-known multi-step or multi-stage process designs, the cascade type of separation unit provides several advantages. Here, the separation process is implemented in it by creating two counter current flows. In one of them is depleted by the high-permeable component in a continuous mode, meanwhile the other one is enriched. Taking into account that the circulating flows rate overcomes the withdrawn one, there is a multiplicative increase in separation efficiency. A comprehensive study of CO
capture using the membrane cascade type of «Continuous Membrane Column» includes the determination of the optimal membrane material characteristics, the sensitivity study of the process, and a feasibility evaluation. It was clearly demonstrated that the proposed process achieves efficient CO
capture, which meets the modern requirements in terms of the CO
content (≥95 mol.%), recovery rate (≥90%), and residual CO
concentration (≤2 mol.%). Moreover, it was observed that it is possible to process CO
with a purity of up to 99.8 mol.% at the same recovery rate. This enables the use of this specific process design in CO
pretreatment operations for the production of high-purity carbon dioxide.
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•Trace H2O to C2H2 conversion on CaC2 in NH3 matrix was studied for GC-FID analysis.•HOCaCCH intermediate formation is assumed and its presence is proved by CaC2 FTIR.•Side reaction rate and the ...condition of CaC2 affect the measurement reproducibility.•Optimal range of ammonia sample flow rates is important for CaC2/GC-FID measurements.•GC-FID moisture analysis is comparable to FTIR by accuracy, but less resource-intensive.
The current study focuses on the processes involved during the flow conversion of water into acetylene in a calcium carbide reaction cell for the trace moisture analysis of ammonia by reaction gas chromatography. The factors negatively affecting the reproducibility and the accuracy of the measurements are suggested and discussed. The intramolecular reaction of the HOCaCCH intermediate was found to be a side reaction producing background acetylene during the contact of wet ammonia gas with calcium carbide. The presence of the HOCaCCH intermediate among the reaction products is confirmed by an FTIR spectral study of calcium carbide powder exposed to wet gas. The side reaction kinetics is evaluated experimentally and its influence on the results of the gas chromatographic measurements is discussed in relation to the determination of the optimal operating parameters for ammonia analysis. The reaction gas chromatography method for the trace moisture measurements in an ammonia matrix was experimentally compared to an FTIR long-path length gas cell technique to evaluate the accuracy limitations and the resource intensity.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
