Hybrid Solvent Research Articles

Experimental measurement of carbon dioxide solubility in 1-methylpyrrolidin-2-one (NMP) + 1-butyl-3-methyl-1H-imidazol-3-ium tetrafluoroborate ([bmim][BF4]) mixtures using a new static-synthetic cell

A new experimental setup based on the “static-synthetic” method was designed and commissioned for the measurement of solubility from vacuum to moderates pressures. The new apparatus and experimental method were extensively validated by measuring the solubility of carbon dioxide in three pure solvents, viz., n-hexane, n-methyl-2-pyrrolidone and 1-butyl-3-methylimidazolium tetrafluoroborate. New solubility data for carbon dioxide in hybrid solvents with different mixtures of 1-butyl-3-methylimidazolium tetrafluoroborate + n-methyl-2-pyrrolidone were measured at three temperatures, viz. (298.15, 313.15 and 323.15) K. Additionally, viscosity, density and sound velocity for binary mixtures of n-methyl-2-pyrrolidone + 1-butyl-3-methylimidazolium tetrafluoroborate were measured. The experimental phase equilibrium data were modelled using the Peng-Robinson equation of state and van der Waals mixing rule. In general, the solubility of carbon dioxide in the hybrid solvent was lower than the respective pure constituents. However, the hybrid solvent exhibited a significantly lower viscosity than the pure ionic liquid.

Ionic Liquids for Controlled Synthesis of Functional Materials for Energy-Related Applications

The conventional synthesis of functional materials relies heavily on water and organic solvents. Alternatively, the synthesis of functional materials using or in the presence of ionic liquids represents a burgeoning direction in materials chemistry.1-4 Ionic liquids are a family of non-conventional molten salts that can act as both templates and precursors to functional materials, as well as solvents. They offer many advantages, such as negligible vapor pressures, wide liquidus ranges, good thermal stability, tunable solubility of both organic and inorganic molecules, and much synthesis flexibility. The unique solvation environment of these ionic liquids provides new reaction media for controlling formation of porous materials, creating functional groups in biphasic media, and tailoring morphologies of advanced materials. Challenges and opportunities in using ionic liquids for synthesizing functional materials in energy-related applications will be discussed. Acknowledgment: This work was conducted at the Oak Ridge National Laboratory and supported by the Office of Basic Energy Sciences, U.S. Department of Energy, under contract No. DE-AC05-00OR22725 with UT-Battelle, LLC. References (1) Ma, Z.; Yu, J. H.; Dai, S. Preparation of Inorganic Materials Using Ionic Liquids. Adv. Mater. 2010, 22, 261-285. (2) Sun, X. Q.; Luo, H. M.; Dai, S. Ionic Liquids-Based Extraction: A Promising Strategy for the Advanced Nuclear Fuel Cycle. Chem. Rev. 2012, 112, 2100–2128. (3) Huang, K.; Chen, F. F.; Tao, D. J.; Dai, S. Ionic liquid-formulated hybrid solvents for CO2 capture. Curr. Opin. Green Sustain. Chem. 2017, 5, 67-73. (4) Yang, Q. W.; Zhang, Z. Q.; Sun, X. G.; Hu, Y. S.; Xing, H. B.; Sheng Dai, S. Ionic liquids and derived materials for lithium and sodium batteries. Chem. Soc. Rev. 2018, 47, 2020-2064.

Replica-Based Protein Structure Sampling Methods: Compromising between Explicit and Implicit Solvents.

The structure of a protein is often not completely accessible by experiments. In silico, replica exchange molecular dynamics (REMD) is the standard sampling method for predicting the secondary and tertiary structures from the amino acid sequence, but it is computationally very expensive. Two recent adaptations from REMD, temperature intervals with global exchange of replicas (TIGER2) and TIGER2A, have been tested here in implicit and explicit solvents. Additionally, explicit, implicit, and hybrid solvent REMD are compared. On the basis of the hybrid REMD (REMDh) method, we present a new hybrid TIGER2h algorithm for faster structural sampling, while retaining good accuracy. The implementations of REMDh, TIGER2, TIGER2A, and TIGER2h are provided for nanoscale molecular dynamics (NAMD). All the methods were tested with two model peptides of known structure, (AAQAA)3 and HP7, with helix and sheet motifs, respectively. The TIGER2 methods and REMDh were also applied to the unknown structure of the collagen type I telopeptides, which represent bigger proteins with some degree of disorder. We present simulations covering more than 180 μs and analyze the performance and convergence of the distributions of states between the particular methods by dihedral principal component and secondary structure analysis.

Multifunctional electrospun nanofibers for wound application – Novel insights into the control of drug release and antimicrobial activity

Therapeutic management of skin wounds is still faced with major challenges associated with chronicity and bacterial infection. Consequently, there is a high clinical need for effective therapeutic approaches addressing these aspects. In this context, electrospun fibers emerged as beneficial carrier systems for local and controlled delivery of wound healing agents, additionally providing a protective barrier against bacterial invasion. However, depending on the material, such fibers were also shown to provide a potential substrate for bacterial colonization and growth. Thus, profound understanding of fiber characteristics and the respective interactions of fibers with biological systems, cells as well as bacteria, is of major importance.To address these issues, we designed drug-loaded hybrid fibers consisting of polycaprolactone (PCL) and chitosan. Pure PCL fibers provided suitable drug release kinetics for wound healing, but were colonized by Pseudomonas bacteria which were used as model pathogens. The addition of chitosan to the fiber matrix reduced the number of adherent bacteria by tenfold compared to pure PCL fibers and did not show any adverse effects to human skin cells. Further, chitosan incorporation significantly improved fiber hydrophilicity, identified as one of the key regulators of optimized cell-fiber interactions. We successfully encapsulated dexpanthenol as an established wound healing active into these hybrid fibers and solvent polarity was found to be a key factor for controlling drug release kinetics from the fibers. For the final formulation, controlled drug release over seven days with a burst release of 11.54% within 3 h could be achieved and the wound healing effect of the fiber mats could successfully be demonstrated in a cell-based wound healing assay as a proof-of-concept. Such multifunctional fibers simultaneously deliver actives and prevent bacterial growth, and consequently show a high potential for future wound therapy.

Determination of 24 personal care products in fish bile using hybrid solvent precipitation and dispersive solid phase extraction cleanup with ultrahigh performance liquid chromatography-tandem mass spectrometry and gas chromatography-mass spectrometry

Personal care products (PCPs) are ubiquitous in aquatic environments owing to the continuous discharge of domestic wastewater from highly urbanized regions. These PCPs can be adsorbed by fish and thereafter usually enter the bile of the fish through biliary excretion. In this study, a sensitive method based on a combination of hybrid solvent precipitation and dispersive solid phase extraction (d-SPE) purification was developed to simultaneously extract and detect 24 PCPs, namely, 16 biocides, 4 synthetic musks, and 4 benzotriazoles, from fish bile. Hybrid precipitation on solid phase extraction (SPE) tubes was applied to remove phospholipids and proteins, and a d-SPE procedure was used for further purification. The extraction solvents for the hybrid precipitation/SPE tubes and d-SPE materials were optimized. The method performance for bile samples both with and without enzyme hydrolysis using β-glucuronidase/aryl-sulfatase were validated. The 24 PCPs in fish bile were spiked with standard concentrations of 10 ng/mL, 20 ng/mL, 100 ng/mL, and 200 ng/mL to evaluate recoveries, which ranged from 70 to 120% for 16, 16, 22, and 21 analytes with hydrolysis, respectively, and 70–120% for 14, 15, 23, and 23 analytes without hydrolysis, respectively. The quantification limits for target PCPs were in the range 0.26–7.38 ng/mL [excluding musk xylene (MX) and musk ketone (MK)] and 0.20–9.48 ng/mL (excluding MX and MK) for bile samples with and without enzyme hydrolysis, respectively. After enzyme hydrolysis, 12 PCPs were detected in bile from fish collected from the Yangtze River, with a maximum detected concentration of 460 ng/mL, for triclosan (TCS). The hydrolysis reaction indicated that high percentages of glucuronide and sulfate metabolites for some PCPs, i.e. four parabens and TCS, existed in the bile.

Hybrid Solvent Helps Ease Bottlenecking in Natural-Gas Plant

This article, written by Special Publications Editor Adam Wilson, contains highlights of paper SPE 188252, “Natural-Gas-Plant Debottlenecking Thanks to Hybrid Solvent,” by Eric Cloarec, Renaud Cadours, and Claire Weiss, Total, prepared for the 2017 Abu Dhabi International Petroleum Exhibition and Conference, Abu Dhabi, 13–16 November. The paper has not been peer reviewed. Processing sour natural gas is a challenge. If mercaptans are present in the sour gas, the limited mercaptan-absorption capacity of the well-known alkanolamine solvents can be a problem. A solution is to replace the usual alkanolamine aqueous solvent with a hybrid formulation that allows simultaneous removal of mercaptans and acid gases. A new solvent has been developed by the addition of a physical component into a generic alkanolamine/water solvent. This hybrid solvent can be used without any plant modification. Introduction More than 40% of identified gas reserves contain acid gases. Over the years, solvent technologies have been developed, demonstrated, and improved for hydrogen sulfide (H2S) and carbon dioxide (CO2) removal. Sour-gas processing has recently seen the requirement of more-stringent specifications for total sulfur compounds, particularly mercaptans and carbonyl sulfide. Producing sour-gas fields in an economic way became a challenge. Indeed, the physicochemical properties of mercaptans allow only very limited reaction with amines under operating conditions. Classical aqueous amine technologies generally are not sufficient to reach mercaptan or total-sulfur specifications. Consequently, additional treatment is required to remove these compounds. The first option to treat a gas containing CO2, H2S, and mercaptans consists of a polishing stage for further mercaptan removal (for example, molecular sieves) downstream from the amine treating process. One drawback of this option is that the gas used for adsorbents regeneration needs to be sweetened, which requires a dedicated unit. Another drawback is that the gas- sweetening unit is generally designed to use a physical solvent, which has high affinity for hydrocarbon. The second option is most often used when the recovery of natural-gas liquids is considered. Mercaptans and other sulfur compounds concentrated in the liquid-hydrocarbon cuts are removed through a caustic-soda process or by molecular sieves. With the first option, the succession of treatment stages requires an increase in plant footprint, which brings unavoidable extended lifecycle costs. Meanwhile, the drawbacks of these schemes include the disposal of the disulfide oil with the caustic-soda process or the treatment of the gas used for molecular-sieve regeneration. The last option is the simultaneous removal of mercaptans, carbonyl sulfide, and acid gases in a single unit by use of a mixture of chemical and physical solvents. However, the mercaptan-removal efficiency is correlated with the solvent composition and flow rate. Design criteria can be for H2S and CO2 removal or for mercaptan elimination. Expenditure optimization will drive the selection of the process scheme: either total mercaptan removal within the gas-sweetening unit or partial mercaptan removal with the hybrid solvent followed by a polishing unit.

Technology Focus: Natural Gas Processing and Handling

Technology Focus Despite a dip earlier in the year, natural-gas prices remained steady over 2017, averaging $2.99/million Btu. According to the US Energy Information Administration (EIA), the decrease in natural-gas price in 2017 was because of the warmer winter and lower gas usage for power generation, which led to lower demand. According to the latest figures from the International Energy Agency, the year-over-year aggregate gross consumption (production plus imports minus exports and stock changes) for US natural gas was up 5.7% in October 2017. Rising demand from Mexico coupled with lower gas prices and greater pipeline capacity resulted in US exports increasing by 0.4 Bcf/D in 2017, and they are expected to increase by a further 0.6 Bcf/D in 2018. In 2017, the US also became a net exporter for the first time since 1957 when taking annual figures into account. Early 2018 has been a different story, however, with natural-gas prices already hitting a couple of peaks (of greater than $5/million Btu according to the Henry Hub Spot Price history). In the US, colder-than-expected temperatures contributed to peaks in demand, but, at the time of writing, the prices have settled down to the pre-“bomb cyclone” levels, with current natural-gas prices almost mirroring those in 2017 (at $2.868/million Btu). The Henry Hub Natural Gas Spot Prices are projected to average $2.88/million Btu in 2018. The EIA predicts that natural-gas usage for residential and commercial purposes will likely increase by 1.3 Bcf in 2018. Industrial consumption is also expected to rise by 1.2% this year, with an average of 21.7 Bcf/D. Dry-natural-gas production is expected to rise to 6.9 Bcf/D (9.3%). Most of the growth in natural gas is expected to be in the Marcellus, Utica, and Permian basins. Similarly, for liquefied natural gas (LNG), the forecasts are rosy, with an expected average rate of 3.0 Bcf/D in 2018. This is because of an expected increase in production from the Cove Point terminal in Maryland and additional facilities coming online this year—namely, the Elba Island facility in Georgia and the Free-port LNG plant in Texas. A novel hybrid solvent for acid-gas removal improves the handling of sour natural gas by effectively dealing with mercaptans present without the need for modifying facilities and with no adverse effects on the sulfur-recovery units down the line. This enables the whole process to be more economical and efficient while meeting the necessary health, safety, and environment requirements. To learn more, visit the 2018 SPE Annual Technical Conference and Exhi-bition in Dallas on 24–26 September and the 2018 SPE Asia Pacific Oil and Gas Conference in Brisbane, Australia, on 23–25 October. Recommended additional reading at OnePetro: www.onepetro.org. SPE 186394 Investigation of Failed LNG Boil-Off Gas-Transfer-Line-Expansion Bellows Using Finite-Element-Analysis Approach by E.Y. Pratama, PT Badak LNG SPE 186932 From Sandface to Processing Plant, an Integrated View of an Operating Envelope in a Gas/Condensate System by M. Sueiro, Repsol, et al. SPE 188347 Overcoming Challenges To Reduce H2S Content in Sales-Gas-Transmission Pipelines by JagannathRao PrakashRao Allamaraju, Abu Dhabi Gas Industries, et al.

Enhanced Swelling, Mechanical and Thermal Properties of Cellulose Nanofibrils (CNF)/Poly(vinyl alcohol) (PVA) Hydrogels with Controlled Porous Structure.

In this work, novel porous cellulose nanofibrils (CNF)/poly(vinyl alcohol) (PVA) hydrogels were prepared using the hybrid solvent of dimethyl sulfoxide (DMSO)/water, followed by freezing/thawing process. Structure, swelling, mechanical and thermal properties of CNF/PVA were explored. The results revealed that porous hydrogels were formed by using the hybrid solvent of DMSO/water, and the pore sizes of hydrogels were controlled by the concentration of CNF. The porous structure of the composite hydrogels can strongly enhance the swelling properties as expected. Compared with pure PVA hydrogels, a 150% improvement in compressive strength were achieved by the hybrid solvent. And the increment of compressive strength depended on the concentration of the CNF. Moreover, the addition of CNF improved the thermal stability of the PVA hydrogels significantly. The low cost, nontoxic and high-performance nanoreinforced hydrogels may have a promising application in tissue engineering fields.

Methyl Mercaptan Absorption Study into a Hybrid Solvent Mixture Composed of Diethanolamine/Methanol/Water at Temperatures from 313.9 to 353.0 K

Methyl mercaptan (CH3SH) absorption kinetics was studied for a hybrid solvent mixture consisting of diethanolamine/water/methanol for concentrations of 40/40/20 wt % and 40/20/40 wt % and for temperatures between 313.9 and 353.0 K. CH3SH is usually found in sour gases and is removed along with other acid gases. Physicochemical characterization is performed for the treatment of CH3SH with the hybrid solvent which is to date lacking chemical absorption data. A systematic methodology is proposed to assess the effect of each mass transfer, thermophysical properties, and the chemical reactions in the system. An empirical novel equation is proposed for the Henry’s law constant solubility of CH3SH with respect to the methanol in solution. A chemical kinetic mechanism based on the formation of a zwitterion complex is proposed for the chemical species in the liquid phase. Results validated with experimental data enabled all the reaction constants to be parametrized in terms of the Arrhenius law.

High-pressure absorption study of CO2 in aqueous N-methyldiethanolamine (MDEA) and MDEA-piperazine (PZ)-1-butyl-3-methylimidazolium trifluoromethanesulfonate [bmim][OTf] hybrid solvents

In present study, high pressure CO2 absorption performance of aqueous N-methyldiethanolamine (MDEA) and its hybrid solvents with anhydrous perazine (PZ) and ionic liquid (IL) 1-butyl-3-methylimidazolium trifluoromethanesulfonate [bmim][OTf] were investigated. The absorption performance of hybrid solvents were carried out to investigate CO2 loading capacity (mol of CO2/mol of solvent), and apparent absorption rate (CO2 capture efficiency, overall rate constant). The CO2 loading capacity of aqueous MDEA and its hybrid solvents were experimentally investigated for a wide range of compositions between pressure ranges of 2 to 50bar and at three different temperatures (303.15, 313.15, and 333.15K). Furthermore, apparent absorption rate performance of hybrid solvents were determined at 303.15K temperature and 2bar pressure. The effect of temperature, CO2 partial pressure, and ionic liquid (IL) concentrations on CO2 loading of aqueous IL-amines hybrid solvents were also investigated. The results indicated that CO2 loading of hybrid solvents were increased with increase in CO2 partial pressure and IL concentration (up to 10wt%), further increased concentration of IL suppressed CO2 loading capacity. The CO2 loading capacity of hybrid solvents were also reduced with rise in system's temperature. The addition of IL and anhydrous PZ significantly enhanced CO2 capture efficiency (nCO2) and overall absorption rate constant (k) of aqueous MDEA solvent.

Feasible ionic liquid-amine hybrid solvents for carbon dioxide capture

Ionic liquid (IL)-amine hybrid solvents have been proved to be an energy-saving system for CO2 capture. Lack of experimental information on the diffusivity and heat of CO2 absorption in IL-amine hybrid solvents hampers the wide application of IL in CO2 capture. In this work, the effects of IL on absorption rate, solubility, diffusivity and heat of CO2 absorption in feasible hybrids of 1-butyl-3-methyl-imidazolium nitrate ([Bmim][NO3]) and monoethanolamine (MEA) have been elaborated using weight method, vapor liquid equilibrium and calorimetric measurement. The results showed that the addition of IL slightly decreases CO2 loading under atmospheric pressure. Based on the measured solubility and calorimeter results, IL is beneficial to improve the physical absorption of CO2 and reduce the heat of absorption in IL-amine hybrids. The diffusivity of CO2 can be maintained at an acceptable level by controlling the concentration of IL. Considering CO2 capacity, kinetics and heat of absorption, the hybrids of 30% MEA+10% [Bmim][NO3]+60% H2O were recommended. Our work gives the meaningful insights on designing novel IL-amine hybrids for CO2 capture.

Solvent Engineering for High-Performance PbS Quantum Dots Solar Cells

PbS colloidal quantum dots (CQDs) solar cells have already demonstrated very impressive advances in recent years due to the development of many different techniques to tailor the interface morphology and compactness in PbS CQDs thin film. Here, n-hexane, n-octane, n-heptane, isooctane and toluene or their hybrids are for the first time introduced as solvent for comparison of the dispersion of PbS CQDs. PbS CQDs solar cells with the configuration of PbS/TiO2 heterojunction are then fabricated by using different CQDs solution under ambient conditions. The performances of the PbS CQDs solar cells are found to be tuned by changing solvent and its content in the PbS CQDs solution. The best device could show a power conversion efficiency (PCE) of 7.64% under AM 1.5 G illumination at 100 mW cm−2 in a n-octane/isooctane (95%/5% v/v) hybrid solvent scheme, which shows a ~15% improvement compared to the control devices. These results offer important insight into the solvent engineering of high-performance PbS CQDs solar cells.

Accelerated CO2 capture in hybrid solvent using co-immobilized enzyme/complex on a hetero-functionalized support

There has been increasing interest in the development of solvent systems for efficient and less energy intensive CO2 capture and desorption. In this work, we have developed a hybrid solvent system (30wt.% MEA+7.5wt% PZ+15wt%K2CO3) containing a thermo-stable carbonic anhydrase (CA) and Zn complex (Zn-Im) together on a hetero-functional support (HFSCaCO3/H3BO3/SiO2) (termed as CA/Zn-Im: HFS). The hybrid solvent containing CA/Zn-Im: HFS exhibit excellent gravimetric CO2 uptake (21.65wt%) over the neat hybrid solvent (13.75wt%). Gravimetric and pressure drop experiments confirmed that HFS and Zn-Im plays key role in improving the CO2 capture activities of CA in hybrid solvent. Low temperature desorption (90°C) suggested that the hybrid solvent containing CA/Zn-Im: HFS has 1.57 times higher desorption kinetics compared to the neat hybrid solvent. Moreover, CA was highly stable in the hybrid solvent medium and could be reused for 15 consecutive cycles with retention of 90% of its initial activity. The development in various key aspects of CO2 capture suggested that the hybrid solvent with CA/Zn-Im: HFS is an efficient solvent system to improve conventional amine based scrubbing technology.

Thermophysical properties of aqueous N-methyldiethanolamine (MDEA) and ionic liquids 1-butyl-3-methylimidazolium trifluoromethanesulfonate [bmim][OTf], 1-butyl-3-methylimidazolium acetate [bmim][Ac] hybrid solvents for CO2 capture

In this research work, thermophysical properties such as density, refractive index, surface tension, and viscosity of aqueous N-methyldiethanolamine (MDEA) and 1-butyl-3-methylimmidazolium trifluoromethanesulfonate [bmim][OTf], 1-butyl-3-methylimmidazolium acetate [bmim][Ac] hybrid solvents were investigated. All thermophysical properties were investigated at an atmospheric pressure, between the temperature ranges of 298.15 to 343.15K with an interval of 5K. In all samples, the concentration of MDEA was kept constant at 30wt%, while the concentration of the ionic liquids was varied between 5–20wt%. Experimental investigation demonstrated that the thermophysical properties were mainly dependent on the temperature and the concentration of the ionic liquids. All thermophysical properties were decreased with increase in temperature of the system. An increasing trend was observed in density, refractive index, and viscosity data with the increase in the concentration of the ionic liquids. The surface tension data for all samples under investigated was found to be in decreasing order with the increase in the concentration of the ionic liquids. It was also noticed that the use of two different ionic liquids has a different impact on the thermophysical properties of the hybrid solvents. Empirical correlations were used to correlate the experimental data of all the properties as a function of temperature and concentration of both the components (IL and amine). The correlated data were found to be in good agreement with the experimental data at all concentrations.

Experimental study of regeneration performance for CO2 desorption from a hybrid solvent MEA‐methanol in a stripper column packed with three different packing: Sulzer BX500, mellapale Y500 and pall rings 16 × 16

The regeneration heat duty (Qreg, MJ/kg CO2) which consists of solvent heating energy (Qsh, MJ/kg CO2), solvent vaporization energy (Qvap, MJ/kg CO2), and desorption energy (Qdes, MJ/kg CO2), is a critical parameter in evaluating the performance of a solvent for postcombustion CO2 capture. In this study, Qreg of CO2 desorption from rich monoethanolamine (MEA)‐methanol solvent was experimentally evaluated in a pilot‐plant stripper packed with Sulzer packing BX500, Mellapale packing Y500 and Pall rings 16 × 16. And a comparison of Qreg between MEA‐methanol and aqueous MEA solvent was performed to evaluate the potential for MEA‐methanol's application in industrial CO2 capture process. Also effects of several operating parameters of the stripper consists of rich CO2 loading (0.25–0.52 mol/mol), rich solvent flow rate (21.2–51.4 L/h), rich solvent temperature (40–60°C) and regeneration temperature (68–74°C) on the regeneration performance of the stripper were studied. It was found that Qreg of MEA‐methanol solvent was lower than aqueous MEA solvent (especially Qdes) and Qreg was sensitive to all the four parameters. Also the results obtained in this work showed that the stripper performance of Sulzer BX500 packing was better than Mellapale Y500 packing and Pall rings 16 × 16 packing was the worst. © 2017 American Institute of Chemical Engineers Environ Prog, 36: 838–844, 2017

Thermophysical properties of concentrated aqueous solution of N -methyldiethanolamine (MDEA), piperazine (PZ), and ionic liquids hybrid solvent for CO 2 capture

In the present study, thermophysical properties such as density, refractive index, surface tension, and viscosity of the concentrated aqueous solution of N-methyldiethanolamine (MDEA), piperazine (PZ), and ionic liquids (ILs) 1-butyl-3-methylimidazolium trifluoromethanesulfonate [bmim][OTf], 1-butyl-3-methylimidazolium acetate [bmim][AC] were investigated. All the properties were measured at atmospheric pressure and temperature ranging from (298.15–343.15) K, with a regular interval of 5 K. The concentrations of N-methyldiethanolamine (MDEA) and piperazine (PZ) were kept constant at 30 and 3 wt%, respectively, while the concentration of ionic liquids [bmim][OTf], [bmim][AC] were varied between 5 and 20 wt%. All the properties under investigation demonstrated their significant dependence on temperature and ionic liquid concentration. Increasing temperature showed decreasing trend of density, viscosity, refractive index, and surface tension of the hybrid solvents. Except for surface tension, density, refractive index, and viscosity were increased by increasing the concentration of ionic liquid in the hybrid solvents. Surface tension data were decreased with an increase in the concentration of ionic liquids at a constant temperature. The thermophysical properties of concentrated aqueous solution of hybrid solvents were correlated using an empirical correlations approach with respect to temperature and concentration. A good agreement was found between the correlated and experimental data at all conditions.

Orthogonal test design to optimize the operating parameters of a hybrid solvent MEA–Methanol in an absorber column packed with three different packing: Sulzer BX500, Mellapale Y500 and Pall rings 16 × 16 for post-combustion CO2 capture

Effects of three important operating conditions (liquid flow rate, gas flow rate and regeneration temperature) on the CO2 capture and mass transfer performance of the absorption of CO2 into a hybrid solvent MEA–Methanol were studied in a pilot-plant absorber packed with three different packings consisting of Sulzer BX500, Mellapale Y500 and Pall rings 16 × 16 through orthogonal tests. CO2 absorption experiment was conducted under the optimal operating parameters of three packings achieved from the orthogonal experiments (liquid flow rate 30l/h, flue gas flow rate 3m3/h and regeneration temperature 74°C for Mellapale packing 500Y, liquid flow rate 40l/h, flue gas flow rate 3m3/h and regeneration temperature 74°C for Pall rings packing 16 × 16 and liquid flow rate 40l/h, flue gas flow rate 5m3/h and regeneration temperature 74°C for Sulzer packing BX500). The results showed that regeneration temperature was the most important factor affecting the CO2 capture efficiency and gas flow rate had little effect on the CO2 capture efficiency. In addition, the optimal operating conditions of the three packings were achieved in this study and Sulzer BX500 packing had the best mass transfer performance.

Study of hydrogen sulfide absorption with diethanolamine in methanolic aqueous solutions

The sulphur compounds are removed by various processes, among which that corresponding to the gas absorption in specific liquid solutions. This absorption is carried out by physical, chemical solvents and currently by mixing both in the so called hybrid solvents. In this work, hydrogen sulphide (H2S) absorption in a hybrid solvent containing aqueous Di-Ethanol-Amine (DEA) dissolved in methanol have been studied extensively in a modified Lewis cell reactor. Experiments have been achieved in an extended range of temperature, 313-353 K and with two mixtures (50% water, 30%DEA, 20% Methanol), (40% water, 40% DEA, 20% methanol). Through these experiments, three parameters affecting the absorption of hydrogen sulfide (temperature T, loading rate (mol H2S/mol DEA) and mass fraction %) were studied. Absorption is accelerated by raising the temperature while it is penalized by the increase in the loading rate. The absorption rate increases as the mass fraction of DEA varies from 30% to 40% to achieve an optimum loading rate (=0.25(1)at T =333 K and = 0.50 at T=353 K) for hich the absorption rate remains practically unchanged.

An Efficient Synthesis Strategy for Metal-Organic Frameworks: Dry-Gel Synthesis of MOF-74 Framework with High Yield and Improved Performance.

Vapor-assisted dry-gel synthesis of the metal-organic framework-74 (MOF-74) structure, specifically Ni-MOF-74 produced from synthetic precursors using an organic-water hybrid solvent system, showed a very high yield (>90% with respect to 2,5-dihydroxyterepthalic acid) and enhanced performance. The Ni-MOF-74 obtained showed improved sorption characteristics towards CO2 and the refrigerant fluorocarbon dichlorodifluoromethane. Unlike conventional synthesis, which takes 72 hours using the tetrahydrofuran-water system, this kinetic study showed that Ni-MOF-74 forms within 12 hours under dry-gel conditions with similar performance characteristics, and exhibits its best performance characteristics even after 24 hours of heating. In the dry-gel conversion method, the physical separation of the solvent and precursor mixture allows for recycling of the solvent. We demonstrated efficient solvent recycling (up to three times) that resulted in significant cost benefits. The scaled-up manufacturing cost of Ni-MOF-74 synthesized via our dry-gel method is 45% of conventional synthesis cost. Thus, for bulk production of the MOFs, the proposed vapor-assisted, dry-gel method is efficient, simple, and inexpensive when compared to the conventional synthesis method.

Orthogonal test design to optimize the operating parameters of CO2 desorption from a hybrid solvent MEA-Methanol in a packing stripper

Effects of three important operating conditions (rich solvent flow rate, rich solvent loading and regeneration temperature) on the regeneration performance of the desorption of CO2 from a hybrid solvent MEA-Methanol were studied in a pilot-plant stripper packed with three different packing consist of Sulzer BX500, mellapale 500Y and Pall rings 16 × 16 through the orthogonal tests. The results showed that regeneration temperature was the most important factor affected the CO2 cyclic capacity Δɑ and the solvent flow rate was the most important factor affected the regeneration heat duty Qreg. And the optimal operating conditions under three packing were as follows: rich solvent flow rate = 30L/h, the rich solvent loading = 0.5 molCO2/molamine and the regeneration temperature affected Δɑ and Qreg greatly, a higher regeneration temperature caused a bigger Δɑ and a higher Qreg. In addition, the regeneration performance of Sulzer packing BX500 was the best and that of Pall rings packing 16 × 16 was the worst achieved in this study.