Poly Ethylene Glycol Dimethyl Ether Research Articles

Thermodynamic and Transport Properties of Crown-Ethers: Force Field Development and Molecular Simulations.

Crown-ethers have recently been used to assemble porous liquids (PLs), which are liquids with permanent porosity formed by mixing bulky solvent molecules (e.g., 15-crown-5 ether) with solvent-inaccessible organic cages. PLs and crown-ethers belong to a novel class of materials, which can potentially be used for gas separation and storage, but their performance for this purpose needs to be assessed thoroughly. Here, we use molecular simulations to study the gas separation performance of crown-ethers as the solvent of porous liquids. The TraPPE force field for linear ether molecules has been adjusted by fitting a new set of torsional potentials to accurately describe cyclic crown-ether molecules. Molecular dynamics (MD) simulations have been used to compute densities, shear viscosities, and self-diffusion coefficients of 12-crown-4, 15-crown-5, and 18-crown-6 ethers. In addition, Monte Carlo (MC) simulations have been used to compute the solubility of the gases CO2, CH4, and N2 in 12-crown-4 and 15-crown-5 ether. The computed properties are compared with available experimental data of crown-ethers and their linear counterparts, i.e., polyethylene glycol dimethyl ethers.

Energy and exergy investigation on two improved IGCC power plants with different CO2 capture schemes

Two power generation systems composed of the chemical looping air separation (CLAS) technology and the integrated gasification combined cycle (IGCC) with CO2 capture are conceptually presented, thermodynamically analyzed and compared. Different CO2 capture approaches including the pre-combustion with polyethylene glycol dimethyl ether (PGDE) and the post-combustion with monoethanolamine (MEA) are respectively adopted in the two systems. Blocked energy losses and exergy destructions are calculated to investigate the overall efficiencies of the systems. Sensitivity analyses are carried out to investigate the effects of different operating parameters including the oxygen to coal mass ratio (ROC), the steam to coal mass ratio (RSC) and the temperature of the reduction reactor (TRR) on the energy efficiencies (ηen) and exergy efficiencies (ηex) of the two systems. The maximum energy losses and exergy destructions are found in the CO2 capture units. ROC of 0.75, RSC of 0.06 and TRR of 850 °C are recommended as the optimum operation parameters based on the sensitivity analyses. With the optimized parameters, the energy and exergy efficiencies are predicted to be 37.36% and 34.50% for the system with post-combustion CO2 capture, while 38.67% and 36.19% for the system with pre-combustion CO2 capture.

Study of phase equilibria of aqueous two phase system containing poly ethylene glycol di-methyl ether 2000 and sodium nitrate at different temperatures and application of this system in separation of iodine

In this work, the liquid–liquid equilibrium of {polyethylene glycol di-methyl ether 2000 (PEGDME2000)+NaNO3+H2O} system has been determined experimentally at T=(298.15, 308.15 and 318.15)K and atmospheric pressure (≈85kPa). The Merchuk equation and an empirical equation were used for reproducing the experimental binodal results, and their fitting parameters were obtained with the temperature dependence expressed in the linear form with (1/(T−T0))K as a variable. The tie-line data were correlated by using Othmer-Tobias and Bancroft equations, Setschenow type equation, and osmotic virial model. Moreover, the effect of temperature on the binodal curves and the tie-lines for the investigated aqueous two-phase system have been studied. Also, the free energies, enthalpies and entropies of cloud points for this system was calculated from which it was concluded that the increase of the entropy is the driving force for formation of this aqueous two-phase system. In addition the partitioning behaviour of the iodine molecule on the investigated aqueous two-phase system was studied.

Aqueous two-phase system based on cholinium chloride and polyethylene glycol di-methyl ether 250 and it use for acetaminophen separation

The goal of this work is to study the aqueous two-phase system composed of polyethylene glycol di-methyl ether 250 (PEGDME250) and cholinium chloride at T=(298.15, 308.15 and 318.15)K and atmospheric pressure (≈85kPa). First the binodal data and tie-lines were determined for this system at the temperatures mentioned. Moreover, the Merchuk equation with the temperature dependency and an empirical equation were used for representing the experimental binodal results. The Othmer-Tobias and Bancraft, a temperature dependent Setschenow equation and Osmotic virial model were used to fit the tie-line values of this system. The Gibbs energies, enthalpies and entropies of cloud points were calculated at the temperatures measured in order to investigate the driving force formation of this two-phase system. The use of this system for separation of acetaminophen, as a model of the drug was also examined. The effects of tie-line length and temperature on the drug separation were also researched. Finally, the equation proposed by Diamond-Hsu was used to the correlate the acetaminophen experimental partition coefficients in the two-phase system studied.

CO2-selective mixed matrix membranes (MMMs) containing graphene oxide (GO) for enhancing sustainable CO2 capture

In this study, GO was deliberately incorporated into cross-linked poly (ethylene oxide) (PEO) matrix to obtain novel CO2-selective mixed matrix membranes (MMMs) for sustainable CO2 capture. Various characterizations have been carried out to explore the physicochemical properties of cross-linked PEO membranes before and after GO incorporations. The cross-sectional morphologies of MMMs illustrated a favourable polymer-nanofiller interface between GO and PEO matrix. The mechanical tests indicated the enhanced mechanical properties of membranes after GO incorporation. The gas transport performance of MMMs was investigated in detail. Interestingly, the GO incorporation obviously enhanced the gas permeability of pristine cross-linked PEO membrane because GO restrains the molecular chain entanglement and expands the cross-linked network structures, resulting in the increased fractional free volume (FFV). The gas permeabilities of MMMs demonstrate the highest values at 1.0wt% GO contents. Furthermore, the incorporation of poly(ethylene glycol) dimethyl ether (PEGDME) into MMMs significantly improved the gas transport properties. The improved mechanical properties and excellent CO2 capture performance of GO incorporated PEO network membrane disclosed in this study provide the new opportunity to tackle energy and environmental issues.

Evaluation of biogas upgrading technologies using a response surface methodology for process simulation

Biogas is commonly upgraded to biomethane to produce a better biofuel. The aim of this work is to compare different types of solvents in biogas upgrading while using an absorber-stripper process. A conventional single-loop absorber-stripper process configuration was simulated with ProMax® for three types of solvents: diglycolamine (DGA), dimethyl ethers of polyethylene glycol (DEPG) and water. Absorption temperature, absorption pressure, CO2 concentration, solvent circulation rate and steam rate (only for DGA) were considered as varying parameters. The effects of these parameters on energy consumption, CO2 capture and CH4 recovery were studied by applying response surface methodology (RSM) to the simulations of the processes. The comparison of the processes at the optimum operating conditions for RSM with the three solvents has shown that the process with water is the simplest and most robust of the three, obtaining high levels of CO2 capture and CH4 recovery with the lowest energy consumption.

Origin of high open-circuit voltage in solid state dye-sensitized solar cells employing polymer electrolyte

Herein, the energy level alignment and electron recombination kinetics in solid state dye-sensitized solar cells (DSCs) employing a solid polymer electrolyte (SPE) have been quantitatively characterized. In order to determine the microscopic origin of the enhanced characteristics in polymer electrolytes, we carried out an extensive study of the photovoltaic properties with respect to the electrolyte type and composition, including a liquid electrolyte (LE) and various salt types and concentrations. We observed a smaller downward shift in the conduction band energy of the TiO2 layer upon contact with the SPE as well as a retarded electron recombination rate. These led to an increase in the Voc for DSCs with an SPE, which is mostly attributable to the coordinative interactions of the ethylene oxide (EO) units in poly(ethylene oxide) (PEO) and poly(ethylene glycol) dimethyl ether (PEGDME) with metallic Li+ ions and Ti atoms. Such coordinative interactions induce 1) the capture of Li+ cations in the bulk of the polymer electrolyte, thereby reducing their effective concentration and 2) the facile formation of a PEO passivation layer on top of the TiO2 layer. Therefore, it was concluded that the high Voc in solid state DSCs employing a polymer electrolyte is attributable to the coordinative properties of the EO units in PEO and PEGDME in the SPE.

Solubilities and Thermodynamic Properties of Carbon Dioxide in Some Biobased Solvents

Using the isochoric saturation method, solubilities of CO2 in five biobased solvents (BBSs) have been determined at temperatures between 293.15 and 323.15 K with 10 K intervals and pressure scope of (0–600.0) kPa. The BBSs were selected from glyceryl triacetate (GT), glycerol formal (GF), dl-1,2-isopropyli-deneglycerol (GAK), triethyl citrate (TEC), and acetyl triethyl citrate (ATEC). Henry’s constants and thermodynamic properties such as Gibbs free energy, enthalpy, and entropy of dissolution were derived from the solubility data. The gravimetric solubilities of CO2 in BBSs changed with the sequence of GT > ATEC > TEC ≈ GAK > GF. All the dissolution enthalpies were negative at each condition. The dissolution capacities of BBSs for CO2 were further compared with those of several common absorbents as well as ionic liquids. It was shown that they were similar to polyethylene glycol dimethyl ether (NHD) which is an industrial CO2 absorbent.

Simultaneous small-angle neutron scattering and Fourier transform infrared spectroscopic measurements on cocrystals of syndiotactic polystyrene with polyethylene glycol dimethyl ethers

Syndiotactic polystyrene (sPS) is a crystalline polymer which has a unique property; it is able to form cocrystals with a wide range of chemical compounds, in which the guest molecules are confined in the vacancies of the host sPS crystalline region. Recently, it has been found that even polyethylene glycol oligomers with a molecular weight of more than several hundreds can be introduced into the sPS crystalline region. It is quite important to know how such a long-chain molecule is stored in the host sPS lattice. To tackle this issue, a new simultaneous measurement method combing small-angle neutron scattering and Fourier transform infrared spectroscopy (SANS/FTIR), which has been recently developed by the authors, was applied to an sPS cocrystal with polyethylene glycol dimethyl ether with a molecular weight of 500 (PEGDME500). The temperature-dependent changes of the SANS profile and FTIR spectrum were followed from room temperature up to 413 K for a one-dimensionally oriented SANS/PEGDME500 cocrystal sample. The intensity of the reflections due to the stacking of crystalline lamellae showed a significant temperature dependence. The two-dimensional pattern in the high Q region of SANS also changed depending on temperature. The combined information obtained by SANS and FTIR suggested that PEGDME500 molecules are distributed in both the crystalline and amorphous regions in the low-temperature region close to room temperature, but they are predominantly included in the amorphous region in the high-temperature region. It was also suggested by the two-dimensional SANS profile that PEGDME500 molecules in the crystalline region have an elongated structure along the thickness direction of the crystalline lamellae.

Investigation of the Solubilities of Carbon Dioxide in Some Low Volatile Solvents and Their Thermodynamic Properties

Solubilities of CO2 have been measured in five low volatile organic solvents at temperatures ranging from 293.15 to 323.15 K with 10K intervals under a pressure of 0 to 600.0 kPa using an isochoric saturation method. These organic solvents were selected from γ-butyrolactone (GBL), butyl lactate (BL), 1,1,3,3-tetramethylurea (TMU), 1,3-dimethyl-2-imidazolidinone (DMI), and 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (DMPU). Henry’s constants and thermodynamic properties such as Gibbs free energy, enthalpy, and entropy of dissolution were derived from the corresponding solubility data. The gravimetric solubilities of CO2 in these solvents followed the sequence of TMU > DMI ≈ BL ≈ GBL > DMPU. The enthalpies of dissolution were all exothermal at each condition. Henry’s constants of CO2 in these solvents were further compared with those in ionic liquids and other ordinary absorbents, and it was found that they were similar to that of CO2 in polyethylene glycol dimethyl ether (NHD), which is widely used ...

Enhanced Electrochemical Stability of Quasi-Solid-State Electrolyte Containing SiO2 Nanoparticles for Li-O2 Battery Applications.

A stable electrolyte is required for use in the open-packing environment of a Li-O2 battery system. Herein, a gelled quasi-solid-state electrolyte containing SiO2 nanoparticles was designed, in order to obtain a solidified electrolyte with a high discharge capacity and long cyclability. We successfully fabricated an organic-inorganic hybrid matrix with a gelled structure, which exhibited high ionic conductivity, thereby enhancing the discharge capacity of the Li-O2 battery. In particular, the improved electrochemical stability of the gelled cathode led to long-term cyclability. The organic-inorganic hybrid matrix with the gelled structure played a beneficial role in improving the ionic conductivity and long-term cyclability and diminished electrolyte evaporation. The experimental and theoretical findings both suggest that the preferential binding between amorphous SiO2 and polyethylene glycol dimethyl ether (PEGDME) solvent led to the formation of the solidified gelled electrolyte and improved electrochemical stability during cycling, while enhancing the stability of the quasi-solid state Li-O2 battery.

Density, Speed of Sound, and Viscosity of Some Binary and Ternary Aqueous Polymer Solutions at Different Temperatures

Density, speed of sound and viscosity measurements at (288.15, 293.15, 298.15, 303.15 and 308.15) K were carried out on several binary (water + polymer) and ternary (water + polymer (1) + polymer (2)) systems. Polymers were polyethylene glycol 600 (PEG600), polyethylene glycol 10000 (PEG10000), polypropylene glycol 400 (PPG400), polyethylene glycol dimethyl ether 250 (PEGDME250), and polyvinylpyrrolidone 10000 (PVP10000). The measured density and speed of sound data were used to determine the excess specific volume, isentropic compressibility, and isentropic compressibility increment of the investigated solutions as well as the apparent specific volume, limiting apparent specific volume, limiting apparent specific expansibility, apparent isentropic compressibility, and limiting apparent isentropic compressibility of each polymer in the aqueous solutions of 1 % and 3 % (w/w) other investigated polymers. The intrinsic viscosities for the investigated binary and ternary systems were calculated from the experimental viscosity data. Finally, the ability of polymer (1) in varying the volumetric, compressibility, and viscometric properties of polymer (2) in aqueous solutions was discussed on the basis of the polymer–water and polymer (1)–polymer (2) interactions.

Polyethylene glycol dimethyl ether (PEGDME)-based electrolyte for lithium metal battery

We propose in this work a polyethylene glycol dimethyl ether (MW 500) dissolving lithium trifluoromethansulfonate (LiCF3SO3) salt as suitable electrolyte media for a safe and efficient use of the lithium metal anode in battery. Voltammetry and galvanostatic tests reveal significant enhancement of the electrolyte characteristics, in terms of cycling life and chemical stability, by the addition of lithium nitrate (LiNO3) to the solution. Furthermore, PFG NMR measurements suggest the applicability of the electrolyte in battery in terms of ionic conductivity, lithium transference number, ionic-association degree and self-diffusion coefficient. Accordingly, the electrolyte is employed in a lithium battery using lithium iron phosphate as the selected cathode. The battery delivers a stable capacity of 150 mAh g−1 and flat working voltage of 3.5 V, thus leading to a theoretical energy density referred to the cathode of 520 Wh kg−1. This battery is considered a suitable energy storage system for advanced applications requiring both high safety and high energy density.

Phosgene-free decomposition of dimethylhexane-1,6-dicarbamate over ZnO

In catalytic decomposition of dimethylhexane-1,6-dicarbamate (HDC) into hexamethylene-1,6-diisocyanate (HDI), Zn-containing homogeneous (i.e., zinc acetate) and heterogeneous (i.e., ZnO) catalysts were active among a number of catalysts tested, due to the great electron withdrawing ability of Zn ions. Particularly, when polyethylene glycol dimethyl ether was used as a solvent, ZnO was found to be relatively robust, because the catalytic performance was maintained up to the third use (HDC conversion of 93 % and HDI yield of 67 % at 180 °C for 1 h). Through investigation of a HDC/ZnO mixture at elevated temperatures by IR spectroscopy, a possible reaction scheme of ZnO-catalyzed decomposition of HDC was proposed. The H atom is removed from the N–H group of HDC by hydrogen bonding with an O site on the ZnO surface, followed by coordination of an O–C=O group in monodentate mode to a Zn site. The C–O group in the O–C=O linkage is then cleaved yielding the isocyanate and surface methoxide species. Finally, methanol is released from ZnO by a reaction between the surface methoxide and the hydroxyl species.

The effect of temperature and molar mass on the (liquid + liquid) equilibria of (poly ethylene glycol dimethyl ether + di-sodium hydrogen citrate + water) systems: Experimental and correlation

The (liquid+liquid) equilibrium for the {polyethylene glycol dimethyl ether 2000 (PEGDME2000)+di-sodium hydrogen citrate+H2O} system was studied at T=(298.15, 308.15 and 318.15)K and atmospheric pressure (≈85kPa). The free energies, enthalpies and entropies of cloud points were calculated in order to investigate the driving force formation of this two-phase system. To investigate the effect of molar mass of the polymer on the binodals and tie-lines, similar measurements were also made at T=298.15K on this two-phase system consisting of the PEGDME with molar masses of 500 and 250g⋅mol−1. The effective excluded volume model was used for representation of the phase-forming ability in PEGDME systems. An empirical and the Merchuck equations with the temperature dependency were used to correlate the binodal curves. The Othmer–Tobias and Bancraft and Setschenow equations, the osmotic virial and the extended NRTL models were used to fit the tie-line data.

Economic assessment and optimization of the Selexol process with novel additives

Despite the rising concern with climate change, carbon capture is yet to be implemented widely in industry due to its high cost. In this study, three candidate compounds, dimethyl carbonate (DMC), diethyl carbonate (DEC), and triacetin (TAT), are considered as additives for the solvent, Dimethyl Ethers of Polyethylene Glycol (DEPG), to improve the economics of the Selexol process. To discuss their economic feasibility, the 1-stage Selexol process employing each solvent additive is developed, and their operating and equipment costs are compared with those of the reference process (without the additive). The process employing the TAT additive is shown to be competitive with the reference process in terms of both operating and equipment costs, but DMC and DEC showed a serious problem in terms of solvent loss. For reducing the operating cost and CO2 capture cost further, the lean solvent temperature of the Selexol process with the TAT solvent additive is optimized at various CO2 capture rates.

Fumed Silica-Based Single-Ion Nanocomposite Electrolyte for Lithium Batteries

A composite lithium electrolyte composed of polyelectrolyte-grafted nanoparticles and polyethylene glycol dimethyl ether (PEGDME) is synthesized and characterized. Polyanions immobilized by the silica nanoparticles have reduced anion mobility. Composite nanoparticles grafted by poly(lithium 4-styrenesulfonate) only have moderate conductivity at 60 °C. Almost an order increase of the conductivity to ∼10(-6) S/cm is achieved by co-polymerization of the poly(ethylene oxide) methacrylate with sodium 4-styrenesulfonate, which enhances dissociation between lithium cation and polyanion and facilitates lithium ion transfer from the inner part of the polyelectrolyte layer. This composite electrolyte has the potential to suppress lithium dendrite growth and enable the use of lithium metal anode in rechargeable batteries.

고압에서 알킬카보네이트와 트리아세틴의 이산화탄소 용해도 측정

주제어 : 이산화탄소, 물리 흡수, 용해도, Dimethyl ether of polyethylene glycol (DMPEG), Diethyl carbonate (DEC), 혼합 흡수제 Abstract : The constant-volume method was used to determine the solubility of CO2 in various physical absorbents such as DMPEG (dimethyl ether of polyethylene glycol), DEC (diethyl carbonate), DMC (dimethyl carbonate), and TAT (triacetin) in the total pressure range from 5 to 30 bar. The Peng-Robinson equation of state has been used to describe the equilibrium behavior of these mixtures. It was found that the solubility of absorbents was in the of DMPEG250 > TAT > DEC > DMC at the same temperature. Futhermore, the solubiity of blended absorbent of DMPEG250 and DEC is higher than that of DMPEG 250 alone. Therefore, blended absorbent of DMPEG250 and DEC is expected to be an effective and low cost absorbent for physical absorption in precombustion CO2 capture.

Design optimization of a pre-combustion CO 2 capture plant embedding experimental knowledge

Abstract This work is focused on the design optimization of a pre-combustion CO2 capture plant comprising a sweet high-temperature water–gas shift process and an integrated H2S and CO2 removal process using a mixture of dimethylethers of polyethylene glycol as physical solvent. The steady-state model of the commercial-scale plant has been derived from pilot plant models, which have been extensively validated against experimental data obtained from the pre-combustion CO2 capture facility realized at the Buggenum IGCC power station in the Netherlands. A two-phase optimization-based design approach suited to the use of process simulator environments has been adopted. In the first phase, global design decisions at plant level are evaluated, targeting the minimization of the energy consumption due to CO2 capture. These are the extent of CO conversion in the water–gas shift unit and the percentage of CO2 capture in the removal unit. An optimization of both global design variables is presented considering (i) a wide range of carbon capture targets, (ii) deactivation of catalyst activity throughout the catalyst life and (iii) different operational limits of the steam/CO ratio in the water–gas shift unit. Experimental data from the pilot plant has been used to determine the rate of catalyst deactivation and the operational limits of steam/CO ratio. The second phase of the design procedure targets the local decision variables at unit level. Two studies are presented focusing on: (1) the design of the solvent regeneration and CO2 compression section, and (2) the impact of the solvent temperature on the energy consumption and equipment cost of the removal unit. The design optimization revealed that the specific energy consumption of the pre-combustion capture unit can be reduced by 10% when operating at a minimum molar steam/CO ratio of 1.5 in comparison to the current vendor suggestion of 2.65. These energy savings come at the cost of a lower optimal carbon capture rate, namely 78% instead of 87.5% as reported in the preliminary design.

Screening of conventional ionic liquids for carbon dioxide capture and separation

CO2 capture and storage could efficiently mitigate CO2 emissions, wherein CO2 capture is a crucial energy-intensive process. Ionic liquids (ILs) have been proposed as potential liquid absorbents for CO2 separation. The CO2 absorption capacity and selectivity of ILs have also been investigated extensively. Although ILs have been screened for CO2 separation, only specific ILs have been examined in terms of energy consumption. In this study, 76 conventional ILs were collected and screened in terms of energy consumption to establish potential ILs for CO2 separation. Seventeen ILs were screened according to the CO2 dissolution enthalpy and CO2 working capacity criteria obtained from the Henry’s law constant in the preliminary screening. Seven ILs were then screened from the 17 ILs according to the CO2 working capacity from the measured CO2 solubility in the final screening. The energy consumptions of the seven screened ILs (i.e., [Emim][NTf2], [Bmim][BF4], [Bmim][PF6], [Bmim][NTf2], [Hmim][NTf2], [Bmpy][NTf2], and [Hmpy][NTf2]) were calculated, and the corresponding gas solubility selectivities were discussed. The energy consumptions and properties of the seven screened ILs were compared with those of the commercial CO2 absorbents of 30wt% MEA, 30wt% MDEA, and dimethyl ethers of polyethylene glycol (Selexol™ or Coastal AGR®). The results showed that the energy consumptions of the seven screened ILs were lower than those of the commercial CO2 absorbents. [Hmpy][NTf2] showed the lowest energy consumption among the seven screened ILs under the operating conditions set in this study.