The extraction of aromatics using N-methylpyrrolidone: Liquid-liquidequilibrium determination and mechanism exploration

LLE data of cyclooctane/3-methylpentane + benzene/toluene + N-methylpyrrolidone (NMP) at 298.15 Kand 313.15 K under a pressure of 101.3 kPa were measured in this work. The Othmer-Tobias and Handequations were adopted to validate the reliability of LLE data, where the correlation coefficients (R2) wereclose to unity, indicating the high reliability of the experimental data. The experimental data were analyzed using the distribution coefficient (D) and separation factor (S), and the effect of NMP extracting benzene and toluene from aromatics was explored. Meanwhile, the reason for the different extractionefficiencies of benzene and toluene using NMP was analyzed by quantum chemical calculations. TheNRTL and UNIQUAC thermodynamic models were used to correlate the liquid–liquid equilibrium data,and the relevant binary interaction parameters were obtained. The calculated root mean square deviation(RMSD) were all less than 0.0063, indicating that the obtained binary interaction parameters can be usedto simulate and calculate the extraction of aromatics using NMP.

Measurement and Correlation of Liquid-liquid Equilibria for 1-Hexene-n-Hexane-3-Methysulfolane

Utilizing solvent extraction to separate alkanes and olefins from catalytic light gasoline is an effective method for maximizing the utility of gasoline fractions.This study presents the determination of liquid-liquid equilibrium data for the ternary system of 1-hexene-n-hexane-3-methylsulfolane at 30℃,40℃,and 50℃under atmospheric pressure.The obtained data facilitated the construction of a ternary phase diagram for the system.The results showed that the extraction selectivity of 1-hexene/n-hexane exceeded 1.5 when using 3-methylsulfolane as the extraction solvent.Furthermore,the thermodynamic consistency of the experimental data was examined using Hand’s equation and the Othmer-Tobias method.The correlation coefficient,R^(2)≥0.9578,indicated the acceptable reliability of the phase equilibrium data.Subsequently,the NRTL(non-random two liquid)model was used to correlate the liquid-liquid phase equilibrium data and derive the binary interaction parameter.Notably,the results demonstrated that the root mean square deviation of the NRTL model correlation values from the experimental values did not exceed 2.5%.

Phase Equilibrium of Quaternary System Cd^(2+)//Cl^-,SO_4^(2-),NO_3^--H_2O at 298 K

Solid-liquid equilibrium of quaternary system Cd2＋//Cl–, SO42–, NO3–-H2O at 298 K was studied by means of an isothermal solution saturation method. Experimental results indicate that there are three univariant curves BE, AE and CE, one invariant point E and three crystallization fields in the quaternary system. The quaternary system belongs to a simple type, and there are no double salts or solid solution existing. The crystallization zones of equilibrium solid phases are CdCl2·5/2H2O（AEB field）, 3CdSO4·8H2O（AEC field） and Cd（NO3）2·4H2O（BEC field）, respectively. The composition of the invariant point is CdCl2, Cd（NO3）2, CdSO4 and H2O and the contents of which are 17.02%, 45.50%, 4.52% and 32.96%, respectively. The physico-chemical properties of solution in the quaternary system show regular changes along with the increased cadmium concentration. The results indicate that Cd（NO3）2 possessed the highest solubility among those three salts, which means a strong transfer of Cd ion and a high pollution risk of soil environment. And the solubility of CdSO4 would be restrained as the salts existing together.

Liquid-Liquid Equilibrium for 1-Butanol-Water-KF and 1-Butanol-Water-K_2CO_3 Systems

KF or K2CO3 was added into the 1-butanol-water system and two phases were formed： water-rich phase （water phase） and 1-butanol-rich phase （1-butanol phase）. The liquid liquid equilibrium （LLE） data for 1-butanol-water-KF and 1-butanol-water-K2CO3 systems were measured at 25℃ and showed that 1-butanol phase contained negligible salt and water phase contained negligible 1-butanol when the concentrations of KF and K2CO3 in the water phase were equal to or higher than 27.11% and 31.68% , respectively. Thus water could be separated efficiently from 1-butanol-water by adding KF or K2CO3 into the system. A theoretical calculation of LLE data was calculated by using the Pitzer theory to get water activity in the water phase, and by the models, such as the Wilson, NRTL or the UNIQUAC for the 1-butanol phase. For 1-hutanol-water-KF system, the experimental data were found in good agreement with the calculated results by using Pitzer theory and Wilson equa tion, while for 1-butanol-water-K2CO3 system, the experimental data were found in good agreement with the calculated results by using Pitzer theory and UNIQUAC eauation.

BUBBLE POINT PRESSURE MEASUREMENT FOR ISOTHERMAL QUATERNARY SYSTEM AND PREDICTION OF VAPOR-LIQUID EQUILIBRIUM

1 INTRODUCTIONVapor-liquid equilibrium(VLE)relations are required for practical use,such as in the designand operation of disitillation equipment.In the conventional experimental methods of vapor-liquid equilibria,some analytical instruments are applied.They are time-consuming and dif-ficult for multicomponent system because the proper method for the composition analysis isnot easy to be set up.

Solid-liquid Metastable Equilibria in Quaternary System Li_2SO_4+Li_2CO_3+Li_2B_4O_7+H_2O at 288 K

Metastable equilibrium solubilities and densities of quaternary system Li2SO4＋Li2CO3＋ Li2B4O7＋H2O at 288 K were determined by isothermal evaporation method. According to the experimental data, the metastable equilibrium phase diagram was plotted. The metastable phase diagram had one invariant point F, three double saturated liquid curves ElF, E2F and E3F, and three crystallization fields corresponding to Li2SO4·H2O, Li2CO3 and LiBO2·8H2O. It was found that lithium sulphate（Li2SO4） had the highest concentration and strong salting-out effects on the other salts. There were no solid solutions or double salts formed in the quaternary system at 288 K.

Measurement and correlation of phase equilibrium data of the mixtures consisting of water, resorcinol, mesityl oxide at different temperatures

Liquid–liquid equilibrium(LLE) data were measured for the ternary system of water + resorcinol + mesityl oxide under atmospheric pressure at temperatures of(298.2, 323.2, 333.2, 343.2 and 353.2) K. The reliability of the experimental data was verified by the Hand and Bachman equations. The distribution coefficient and selectivity were calculated from the experimental LLE data, which showed high efficiency of mesityl oxide extracting resorcinol from the aqueous solution. The NRTL and UNIQUAC models were employed to fit the measured experimental LLE data and yield corresponding binary interaction parameters.

Salt effect on the liquid–liquid equilibrium of the ternary (water + phenol + methyl isobutyl ketone) system: Experimental data and correlation

The effects of NaCl, KCl and Na_2SO_4 on the liquid–liquid equilibrium(LLE) data for the ternary system, water+ phenol + methyl isobutyl ketone, were determined at 0.101 MPa and 333.15 K and 343.15 K.The nonrandom two-liquid(NRTL) model was used to correlate the experimental data and to yield corresponding binary interaction parameters for these salt containing systems.The Hand and Othmer–Tobias equations were used to confirm the dependability of the determined LLE data in this work.Distribution coefficient and selectivity were used to evaluate the extraction performance of methyl isobutyl ketone with the existence of salt.The magnitude of salt effect on the water + phenol + methyl isobutyl ketone(MIBK) system is in the following order: Na_2SO_4>NaCl>KCl.

Efficient separation of phenols from coal tar with aqueous solution of amines by liquid-liquid extraction

In this paper,a method of extracting phenols from coal tar by amines aqueous solution was proposed.The effects of various amines on the extraction properties of phenols in coal tar were researched from the views of molecular structure.The parameters such as molar ratio,concentration,extraction time and temperature for the extraction of coal tar by the monoethanolamine and ethylenediamine aqueous solution were examined.The results show that the organic amine with more amino groups,hydroxyl structure and strong electronegativity exhibited better extraction performance.Under the optimal conditions,the extraction yields of phenols in coal tar by the monoethanolamine or ethylenediamine aqueous solution are above 80%,and the recovery yields of amines reach 99%.Furthermore,the probable geometries of complexes formed by the combination of phenols and organic amines were calculated by density function theory.In addition,several thermodynamic models were evaluated through comparing the relative deviation of simulation results by ASPEN PLUS to the experimental ones,which provide feasibility thermodynamic models for the simulation of extraction process.The present work affords a mild,efficient and green approach for the extraction of phenols from coal tar by an aqueous solution of amines in industry application.

Solid-liquid Metastable Equilibria in Quaternary System (NaCl+Na_2CO_3+Na_2SO_4+H_2O) at 273.15 K

The metastable phase equilibria of the quaternary system NaCl＋Na2CO3＋Na2SO4＋H2O were studied at 273.15 K. The salts＇ solubilities, densities and pH values of the equilibrated solution in this system were determined. According to the experimental data, the metastable equilibrium phase diagram, the diagram of density vs. composition and pH vs. composition diagram were plotted. The phase diagram consists of five univariant curves, four crystallization fields and two invariant points. The four crystallization fields correspond to sodium carbonate decahydrate （Na2CO3·10H2O）, sodium sulfate decahydrate（Na2SOn-10H2O）, sodium chloride（NaCl） and burkeite（2Na2SO4. Na2CO3）, respectively. The crystallization field of sodium sulfate decahydrate（Na2SO4.10H2O） is the largest, which indicates that sodium sulfate is easy to saturate and crystallize from solution at 273.15 K.

Simulation of Solvent Extraction for Naphthenic Lubricating Base Oils

Solvent extraction is the process of separating aromatics from vacuum distillates for the production oflubricating base oils. In this study, the authors use dimethyl sulfoxide (DMSO) instead of furfural as solvent, in light of itshigher selectivity, to obtain extracts with a high aromatic content for naphthenic lubricating base oils. We systematicallyinvestigated effects of the solvent-to-oil (S/O) ratio and extraction temperature on the yield of the extract, efficiency ofaromatic removal, and composition of the extracts and raffinates. The results showed that the aromatic content of extractsfor naphthenic oils could reach a high value of about 80%. The solvent maintained a high selectivity for aromatics fornaphthenic oils even under a high S/O ratio and a high extraction temperature. Moreover, the efficiency of aromatic removalfor naphthenic lubricating base oils could be enhanced by increasing either the S/O ratio or the extraction temperature,although these measures had limited effects in practice. Following this, we used the non-random two-liquid (NRTL) modelbased on the pseudo-component approach to simulate the liquid-liquid equilibrium of the system of DMSO + naphtheniclubricating base oils, and determined the parameters of binary interaction through regression based on the data on phaseequilibrium. The modeling results showed that the predicted yield, content of the solvent, and composition of the raffinatesand extracts were in good agreement with those obtained in the experiments. This validates the reliability of the model usedto represent the DMSO + naphthenic lubricating base oil system. Both the experimental data and the method of simulationreported here can help optimize the extraction of naphthenic lubricating base oils, and provide a better understanding of thecorresponding process.

Na^+,K^+//Cl^-,B4O_7^(2-)-H_2O四元体系273K介稳相平衡

采用等温蒸发法研究了四元体系Na+,K+//Cl-,B4O27--H2O273K时的介稳相平衡与相图.测定了该体系273K平衡液相中各组分的溶解度及平衡液相的密度;绘制了该体系的介稳相图.该四元体系273K相图由5条溶解度单变量线、4个结晶区及2个共饱和点组成.体系无复盐或固溶体形成.四个结晶区分别对应单盐NaCl、KCl、K2B4O7·4H2O和Na2B4O7·10H2O.共饱点E1处KCl、NaCl及Na2B4O7·10H2O三盐共饱和,所对应的平衡液相组成为w(Cl-)=29.15%,w(B4O27-)=0.64%,w(K+)=5.97%,w(Na+)=15.55%;共饱和点E2处盐KCl、Na2B4O7·10H2O和K2B4O7·4H2O的三盐共饱和,所对应的平衡液相组成为w(Cl-)=22.84%,w(B4O27-)=10.98%,w(K+)=28.01%,w(Na+)=1.53%.同体系298K时的稳定相图相比,273K时硼酸钠的结晶区变大,而硼酸钾、氯化钠结晶区变小.

NdCl_3-CdCl_2-HCl-H_2O的相平衡及其固相化合物的研究

测定了四元系NdCl3-CdCl2-HCl-H2O(298.15K)的相平衡溶度数据,绘制了相应的溶度图.该四元系是由4个固相区CdCl2·H2O(原始盐)、9CDCl2·NdCl3·20H2O、5CDCl2·NdCl3·13H2O、NdCl3·6H2O(原始盐)组成的复杂体系.用X射线粉末衍射及TG-DTG和荧光光谱对9CdCl2·NdCl3·20H2O和5CdCl2·NdCl3·13H2O进行了研究.荧光研究表明,化合物9CdCh·NdCl3·20H2O具有微弱的荧光强度,5CdCl2·NdCl3·13H2O的荧光强度则相对大于9CDCl2·NdCl3·20H2O的.对X射线粉末衍射进行了指标化.

四元体系Li^+,K^+//CO_3^(2-),B_4O_7^(2-)-H_2O273K介稳相平衡研究

针对西藏扎布耶盐湖卤水组成,用等温蒸发平衡法研究了四元体系Li+,K+//CO23-,B4O27--H2O 273 K的相平衡,测定了平衡时各组分的溶解度及平衡液相的密度。四元体系Li+,K+//CO32-,B4O72--H2O273 K时的相图由5条溶解度单变量线、4个结晶区及2个共饱点组成。4个结晶区分别为对应于盐Li2CO3,K2CO3.1.5H2O,K2B4O7.4H2O及Li2B2O4.16H2O。2个共饱点中,一个为Li2CO3,K2CO3.1.5H2O及K2B4O7.4H2O三盐相称共饱点,另一个为Li2CO3,K2B4O7.4H2O和Li2B2O4.16H2O的三盐不相称共饱点。体系属四元水合物相图Ⅰ型,4种原始组分间未形成复盐或固溶体。对于该四元体系273 K和288 K下的介稳相图发现,碳酸锂盐的溶解度呈现较明显的负温度效应,它在273 K下的结晶相区比在288 K下的要小,且析出固相为偏硼酸锂;而碳酸钾、硼酸钾及硼酸锂结晶区则比288 K下的大。

四元体系KCl-ZnCl_2-HCl(～10.61%)-H_2O(298.15K)的相平衡及其固相化合物

The equilibrium solubility of KCl ZnCl2 HCl(11%) H2O(25℃) quaternary system at 25℃ was determined and the phase diagram was constructed. This system is complicated with two new compounds K2ZnCl4·H2O (2∶1 type) and K5Zn4Cl13·3H2O (5∶4 type) which have been obtained from the system and have been characterized by XRD, TG DTG. The result shows that compound K5Zn4Cl13·3H2O of 5∶4 type is the new one which have not been reported before. For compound K2ZnCl4·H2O parameter of unit cell is a=11.976?, b=9.066?, c=7.015?, and it belong to orthogonal crystalline system. The result of TG DTG shows that compounds K2ZnCl4·H2O and K5Zn4Cl13·3H2O will dehydrate at 400℃ and 670℃, respectively.

CeCl_3-CdCl_2-H_2O和CeCl_3-CdCl_2-HCl-H_2O的相平衡

测定了三元系CeCl3-CdCl2-H2O(25℃)和四元系CeCl3-CdCl2-HCl(～8.4%)-H2O(25℃)的相平衡溶度数据,绘制了相应的溶度图.该三元系是由5个固相区CdCl2·2.5H2O(原始盐)、CdCl2·H2O(原始盐)、6CdCl2·CeCl3·14H2O、4CdCl2·CeCl3·12H2O、CeCl3·7H2O(原始盐)组成的复杂体系.该四元系是由5个固相区CdCl2·H2O(原始盐)、9CdCl2·CeCl3·19H2O、6CdCl2·CeCl3·14H2O、4CdCl2·CeCl3·12H2O、CeCl3·7H2O(原始盐)组成的复杂体系.其中6CdCl2·CeCl3·14H2O在该三元系是介稳化合物.9CdCl2·CeCl3·19H2O、6CdCl2·CeCl3·14H2O和4CdCl2·CeCl3·12H2O用X射线粉末衍射及TG-DTG和DSC等方法进行了研究,并对X射线粉末衍射进行了指标化.

四元交互体系Li^+,K^+//Cl^-,B_4O_7^(2-)-H_2O 323 K相关系研究

采用等温溶解平衡法研究了四元交互体系L i+,K+//C l-,B4O72--H2O 323 K时的相关系。该四元交互体系323 K下的溶解度等温图含有4个盐类结晶相区、5条单变量线和2个无变量点。4个结晶相区分别对应于盐L i C.lH2O、KC、lL i2B4O7.3H2O和K2B4O7.4H2O的结晶区。2个无变量点标注为E和F。E点平衡固相为L iC l.H2O+KC l+L i2B4O7.3H2O,对应的平衡液相组成为w(L i+)6.55%,w(K+)2.16%,w(C l-)34.57%,w(B4O72-)1.89%;F点平衡固相为KC l+L i2B4O7.3H2O+K2B4O7.4H2O,对应的平衡液组成为w(L i+)2.35%,w(K+)2.37%,w(C l-)12.08%,w(B4O72-)4.56%。研究结果表明,该四元交互体系为简单共饱和型,体系中没有复盐和固溶体的形成。

四元交互体系Cd^(2+),Na^+//Cl^-,SO_4^(2-)-H_2O 298 K时的相平衡

采用等温溶解平衡法研究了四元交互体系Cd2+,Na+//Cl-,SO24--H2O在298K的相平衡关系.研究发现,该平衡体系存在Na2CdCl4·3H2O复盐相区,平衡相图中有七条单变度曲线,三个共饱和点和五个结晶相区.其平衡固相的结晶区分别为Na2SO4、CdSO4、CdCl2·2.5H2O、Na2CdCl4·3H2O和NaCl.该四元交互体系平衡液相的物化性质随着Cd2+浓度的增加呈现有规律的变化.研究结果表明,镉盐在该体系中的溶解度大,迁移性强,增加了土壤环境污染风险.

四元体系Na_2B_4O_7-Na_2CO_3-NaHCO_3-NaBO_2-H_2O等温溶度研究(0℃和15℃)

本文首次测定了四元体系Na2B4O7Na2CO3NaHCO3NaBO2H2O在0℃和15℃时的等温溶度和饱和溶液的折光率绘制了相应的溶度图。在0～15℃时该四元体系为简单体系对应4个组分盐或其水合物有4个单饱和结晶区、5条双饱和结晶线和2个三饱和点。

四元体系NaCl-ZnCl_2-HCl(~9%)-H_2O(25℃)的相平衡

The equilibrium solubility of NaCl-ZnCl2-HCl（～9%）-H2O quaternary system at 25℃was determined and the phase diagram was constructed.This system is complicated with one compound 5NaCl·ZnCl2·0.5H2O which has been obtained from the system and has been characterized by XRD.The result shows that compound 5NaCl·ZnCl2·0.5H2O is the new one which has not been reported before.For compound 5NaCl·ZnCl2·0.5H2O parameter of unit cell is a =14.900nm;c=25.160 and it belongs to quadratic system.