System Dimethyl Carbonate Research Articles

The mechanism of the azeotropy eliminating in dimethyl carbonate–ethanol system by extractive distillation applying ionic liquid [BMIM][Tf2N] as entrainer: A combination of FTIR and DFT study

Owing to their outstanding properties, ionic liquids (ILs) have been increasingly applied as entrainers to separate alcohol azeotrope systems in extractive distillation. Fundamental studies on the mechanism of azeotrope breaking are essential for the better use of ILs; however, they are not often reported. To reveal the intrinsic cause of azeotrope breaking by an IL entrainer, on this work, the microstructure features of IL–azeotrope systems were investigated using FTIR and DFT calculations. 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMIM][Tf2N]) and the azeotrope systems dimethyl carbonate (DMC) and ethanol were selected. The v(aromatic C–H) region of the imidazolium cation was analysed first to distinguish the relative interaction strength between the IL and ethanol/DMC. The v(O–D) region of ethanol was applied to identify the interaction complexes in different mixtures and estimate the relative interaction strength between ethanol and the IL/DMC. Combined with DFT calculations, it was found that interactions between [BMIM][Tf2N] and ethanol were stronger than those between [BMIM][Tf2N] and DMC, which could influence the relative vapour pressure of the two constituents, thus breaking the azeotrope. The interactions between ethanol and the IL were stronger than those between ethanol and DMC. Thus, the addition of the IL could break the interaction complex of DMC–ethanol, which is the cause of azeotropy in the DMC–ethanol system. When x(IL) was larger than 0.170, the entire DMC–ethanol complex disappeared accompanied with the eliminated of the azeotrope.

Experimental and theoretical study on physical properties of the systems dimethyl carbonate and diethyl carbonate + pentanol isomers

In many industrial applications that involve solvents, the knowledge of both thermodynamics properties and transport properties play an important role in the design, sustainability, and optimization of processes in different fields of study. However, it is a fact that there is a lack of data and predictive models for the develop of future applications.Taking this into account, in this work we studied the physical properties of carbonates and pentanol isomers as well as their mixtures due to the versality of these solvents in many processes. We present measurements of densities (ρ) and excess molar volumes and enthalpies (VmE, HmE) at 298.15 K for the systems dimethyl or diethyl carbonate + pentanol isomers; and specifically for the systems with diethyl carbonate the surface tensions (σ ) and the surface tension deviations (δσ) at 298.15 K and the viscosities (η), dynamic viscosity deviations (Δη), refractive indexes (nD) and the changes in the refractive index (ΔnD) at 298.15 and 308.15 K. Different theoretical models were applied to obtained data for surface tensions and refractive indexes.

Compressed-liquid densities of the binary mixture dimethyl carbonate + heptane at three compositions

Compressed-liquid densities of the binary system dimethyl carbonate + heptane have been measured with a vibrating-tube densimeter over the temperature and pressure ranges of 270 K to 470 K, and 1 MPa to 50 MPa at three compositions of the mixture. The measurements are part of an effort to better understand the molecular interactions of polar/non-polar mixtures. These types of mixtures often exhibit very non-ideal behavior. By measuring the mixture at three compositions and over a large range of temperature and pressure, the non-ideality can be assessed. There are no high-pressure liquid density data for this binary system in the literature, thus data reported here could only be compared to literature data at atmospheric pressure to establish their quality. The majority of literature data agree well with the presented results which have a maximum expanded uncertainty of 1.63 kg·m−3 (for the composition with the greatest mole fraction of dimethyl carbonate). The non-ideality for the mixture, in the temperature, pressure and composition range of this study was found to be minimal. This is rationalized by considering the molecular sizes, shapes, and charge distributions of the pure components and the attractive parts of their intermolecular force fields as they are reflected in the temperature ranges of their vapor pressure curves.

Solid–liquid equilibria for selected binary systems containing diphenyl carbonate

The solid–liquid equilibrium (SLE) data for five binary systems containing diphenyl carbonate (DPC), i.e., ethanol, 1-propanol, 2-propanol, diethyl carbonate, or dipropyl carbonate + DPC, were determined experimentally. We designed a new experimental apparatus based on a synthetic method for the SLE measurements. We verified the applicability of the designed apparatus by determining the binary SLE data for the system dimethyl carbonate + DPC. The experimental SLE data were represented by a non-random two-liquid model. Predictions of SLE data for the binary systems were also tested on the basis of the National Institution of Standards and Technology-modified universal functional activity coefficient group contribution model.

Liquid–liquid equilibria for the ternary systems DMC–methanol–glycerol, DMC–glycerol carbonate–glycerol and the quaternary system DMC–methanol–glycerol carbonate–glycerol at catalytic reacting temperatures

Liquid–liquid equilibria of multicomponent systems involved in the synthesis of glycerol carbonate from dimethyl carbonate and glycerol were experimentally measured. Particularly, data for the ternary systems dimethyl carbonate+methanol+glycerol and dimethyl carbonate+glycerol carbonate+glycerol and the quaternary system dimethyl carbonate+methanol+glycerol carbonate+glycerol are provided at 333.2K, 338.2K and 343.2K at atmospheric pressure since these temperatures prove relevant for the synthesis of carbonate glycerol from glycerol and dimethyl carbonate. The experimental data obtained were correlated with a good degree of agreement to the NRTL model in order to obtain the corresponding binary interaction parameters.

Highly precise (liquid + liquid) equilibrium and heat capacity measurements near the critical point for [Bmim][BF4] + 1H, 1H, 2H, 2H perfluoroctanol

Liquid+liquid equilibrium of the system [Bmim][BF4]+1H, 1H, 2H, 2H perfluoroctanol using a highly precise methodology based on refractive index measurements was experimentally determined. In addition, isobaric heat capacity near the critical point was obtained. The performance of the new refractive index set-up was successfully checked against the coexistence curve of the system dimethyl carbonate+decane, since highly accurate data are available in the literature. The choice of [Bmim][BF4]+1H, 1H, 2H, 2H perfluoroctanol was motivated by a previous experimental work, whose results suggest that this system could present characteristics of both solvophobic and coulombic behavior, which are the two categories to which an ionic system can belong. Although this was previously observed for other ionic systems, this mixture presented a very striking feature: the diameter of the coexistence curve seemed to change its criticality in the studied temperature range, from solvophobic far away to coulombic close to the critical point. The results of this work reveal that, in fact, [Bmim][BF4]+1H, 1H, 2H, 2H perfluoroctanol presents characteristics of both solvophobic and coulombic criticality, but no evidence of the observed crossover over the experimental temperature range has been found.

Volumetric Properties of the Ternary System Dimethyl Carbonate + Butyl Methacrylate + Allyl Methacrylate and Its Binary Butyl Methacrylate + Allyl Methacrylate at 293.15 K and p=101.325 kPa

Densities of the ternary system dimethyl carbonate + butyl methacrylate + allyl methacrylate and its binary subsystem butyl methacrylate + allyl methacrylate have been measured in the whole composition range, at 293.15 K and atmospheric pressure, using an Anton Paar DMA 5000 oscillating U-tube densimeter. The calculated excess molar volumes of the binary system are positive and were correlated with the Redlich–Kister equation and with a series of Legendre polynomials. Several models were used to correlate ternary behavior from the excess molar volume data of their constituent binaries and found to fit the data equally well. The best fit was based on a direct approach, without information on the component binary systems.

Liquid–Liquid Equilibria for the System Dimethyl Carbonate + Methanol + Glycerol in the Temperature Range of (303.15 to 333.15) K

Liquid–liquid equilibria (LLE) data of the ternary system dimethyl carbonate + methanol + glycerol were measured from (303.15 to 333.15) K. The equilibrium data are correlated with the nonrandom two-liquid (NRTL) model. The reliability of this model is tested by comparison with the experimental results. On the other hand, LLE and vapor–liquid equilibria (VLE) of the binary system dimethyl carbonate + glycerol were also measured under isopiestic pressure (101.3 kPa) and predicted using the NRTL model, with the adjusted parameters obtained from the LLE data of the ternary system dimethyl carbonate + methanol + glycerol. The predicted VLE and LLE for the binary system agreed well with the experimental data.

Organic Salt Effect of Tetramethylammonium Bicarbonate on the Vapor–Liquid Equilibrium of the Dimethyl Carbonate + Methanol System

Isobaric vapor–liquid equilibrium (VLE) data for the systems dimethyl carbonate (DMC) + methanol and DMC + methanol + tetramethylammonium bicarbonate (TMAB) at different salt mole fractions (0.04, 0.07, and 0.10) have been measured at 101.32 kPa. The bubble-point data of the system methanol + TMAB have also been measured at different salt mole fractions. The addition of the organic salt TMAB has a salting-out effect on DMC, and the effect would be enhanced with the increasing salt concentration. The VLE data of the salt-containing system were predicted by the modified Wilson and nonrandom two-liquid (NRTL) models proposed by Tan. The average deviations for the mole fraction of the vapor phase and the bubble point by the modified predictive model were: Δy = 0.011, ΔT = 0.6 K.

Isothermal Vapor−Liquid Equilibrium Data at T = 333.15 K and Excess Molar Volumes and Refractive Indices at T = 298.15 K for the Dimethyl Carbonate + Methanol and Isopropanol + Water with Ionic Liquids

Isothermal vapor−liquid equilibrium (VLE) data at T = 333.15 K are reported for the four ternary systems dimethyl carbonate (DMC) + methanol + 1-ethyl-3-methylimidazolium ethyl sulfate (EMISE), DMC + methanol + 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]), isopropanol + water + EMISE, and isopropanol + water + [Bmim][BF4] by using headspace gas chromatography. The mole fraction of ionic liquids was varied from 0.05 to 0.2. The experimental binary VLE data were correlated using the Wilson, NRTL, and UNIQUAC equations. In addition, the excess volumes and deviations in molar refractivity data are reported at T = 298.15 K for the sub-binary pairs of the above-mentioned ternary systems. These properties are correlated with the Redlich−Kister equation. Finally, the ternary excess volumes and deviations in molar refractivity data were calculated from the Radojkovic equation using correlated binary Redlich−Kister parameters.

Isothermal vapor–liquid equilibrium at 333.15 K and excess molar volumes and refractive indices at 298.15 K for the mixtures of di-methyl carbonate, ethanol and 2,2,4-trimethylpentane

Isothermal vapor–liquid equilibrium data at 333.15 K are measured for the binary system ethanol + 2,2,4-trimethylpentane and for ternary system di-methyl carbonate (DMC) + ethanol + 2,2,4-trimethylpentane by using headspace gas chromatography. The experimental binary and ternary vapor–liquid equilibrium data were correlated with different activity coefficient models. Excess volume and deviations in molar refractivity data are also reported for the binary systems DMC + ethanol and DMC + 2,2,4-trimethylpentane and the ternary system DMC + ethanol + 2,2,4-trimethylpentane at 298.15 K. These data were correlated with the Redlich-Kister equation for the binary systems and the Cibulka equation for the ternary system, respectively. The ternary excess volume and deviations in molar refractivity data were also compared with estimated values from the binary contribution models of Tsao–Smith, Kohler, Rastogi and Radojkovič.

Determination of the critical anomaly in the viscosity for the dimethyl carbonate + (undecane or dodecane) systems

The viscosity critical behaviour for the binary systems dimethyl carbonate + undecane and dimethyl carbonate + dodecane is investigated. To this end, measurements of viscosity at critical composition for both systems were performed as a function of temperature. Data at non-critical composition were also obtained, since to describe this critical anomaly it is necessary to determine the regular part. As the viscosity measurements are distorted by the non-zero shear conditions in which the data were obtained, corrections to obtain the viscosity at zero shear are needed. They involve the knowledge of the correlation length near the critical point. In order to obtain it, measurements of the heat capacity near the critical point were performed for both systems. From these data and from the universality of the two-scale factor, correlation length is obtained. The critical exponent and the critical amplitude of the viscosity thus obtained are coherent with previous results.

Liquid–liquid equlibria of the system dimethyl carbonate + methanol + water at different temperatures

In this work, experimental liquid–liquid equilibria (LLE) data of the dimethyl carbonate + methanol + water system are presented. The LLE of this system has been measured from 283 to 333 K. On the other hand, LLE and LVE of the binary system dimethyl carbonate + water have been measured. The equilibrium data presented are correlated using NRTL and UNIQUAC equations. The reliability of these models is tested by comparison with experimental results. Finally, the VLE for the system DMC + water at 101.3 kPa was predicted using the UNIQUAC model, with the adjusted parameters obtained from the LLE data. This prediction was successful when is compared with the experimental VLE data.

Isobaric molar heat capacities of the ternary system dimethyl carbonate + p-xylene + n-decane

Isobaric molar heat capacities at atmospheric pressure were determined for the ternary system dimethyl carbonate + p-xylene + n-decane and the corresponding binary mixtures dimethyl carbonate + p-xylene, dimethyl carbonate + n-decane and p-xylene + n-decane over the whole composition range at 288.15, 298.15 and 308.15 K. From these data, excess isobaric molar heat capacities were calculated using the Benson and Kiyohara's criterion. The obtained values for the binary systems were correlated using a Redlich–Kister polynomial, whereas the ternary contribution was fitted by means of the Nagata equation. The data present a gradual crossover from a W-shaped composition dependence, typical in alkyl carbonate + alkane systems, to negative parabolic curves, often found for alkyl carbonate + aromatic hydrocarbon and for aromatic + linear hydrocarbon systems. The results are discussed in terms of the degree of randomness of the mixtures.

Thermodynamic behaviour of the binary systems dimethyl carbonate + n-octane or n-nonane

Isobaric molar heat capacities, densities and speeds of sound were determined for the dimethyl carbonate + n-octane and n-nonane systems at atmospheric pressure covering the whole composition interval and in the temperature range (288.15–308.15 K). From these data, derived properties and excess magnitudes were obtained. A strongly temperature-dependent W-shaped curves against composition were observed for excess isobaric molar heat capacities in both system, showing the other excess magnitudes regular tendencies. From these results, a comparative analysis of the existing differences between the thermodynamic behaviour of the two systems was carried out.

High voltage stable liquid electrolytes for Li 1+ xMn 2O 4/carbon rocking-chair lithium batteries

A high voltage oxidation-resistant electrolyte is required for Li 1+ x Mn 2O 4/carbon rocking-chair cells that need to be charged up to a voltage higher than 4.3 V. Many electrolyte compositions have been tested for their ability to resist to high voltages on Li 1+ x Mn 2O 4 electrodes and their ability to maintain high ionic conductivity in a wide temperature range. This survey allowed us to select new electrolyte compositions in the system dimethyl carbonate (DMC) + ethylene carbonate (EC) + lithium hexafluorophosphate (LiPF 6) that are kinetically stable up to almost 5 V versus lithium at 55 °C on Li 1+ x Mn 2O 4 electrodes. Low rate potentiostatic experiments, coupled with coulombmetric measurements in the 4.25–5.1 V range, allowed to select the following compositions: (DMC + EC) (1:2) + 1 M LiPF 6 and (DMC + EC) (2:1) + 1.5 M LiPF 6 as the best. These compositions have been used in practical Li 1+ x Mn 2O 4/carbon rocking-chair batteries and show better performance in terms of cycle life and self-discharge over a wider temperature range. They are compatible with rocking-chair batteries based on LiCoO 2 and LiNiO 2 as well.