The separation of methanol(MeOH)and dimethyl carbonate(DMC)is important but difficult due to the formation of an azeotropic mixture.In this work,isobaric vapor–liquid equilibrium(VLE)data for the ternary systems cont...The separation of methanol(MeOH)and dimethyl carbonate(DMC)is important but difficult due to the formation of an azeotropic mixture.In this work,isobaric vapor–liquid equilibrium(VLE)data for the ternary systems containing different imidazolium–based ionic liquids(ILs),i.e.MeOH+DMC+1-butyl-3-methy-limidazolium bis[(trifluoromethyl)sulfonyl]imide([Bmim][Tf2N]),MeOH+DMC+1-ethyl-3-methyl-imidazolium bis[(trifluoromethyl)sulfonyl]imide([Emim][Tf2N]),and MeOH+DMC+1-ethyl-3-methylimidazolium hexafluorophosphate([Emim][PF6])were measured at 101.3 kPa.The mole fraction of IL was varied from0.05 to 0.20.The experimental data were correlated with the NRTL and Wilson equations,respectively.The results show that imidazolium-based ILs were beneficial to improve the relative volatility of MeOH to DMC,and[Bmim][Tf2 N]showed a much more excellent performance on the activity coefficient of MeOH.The interaction energies of system components were calculated using Gaussian program,and the effects of cation and anion on the separation coefficient of the azeotropic system were discussed.展开更多
The salt effect on the vaporliquid phase equilibrium(VLE)of solvent mixtures is of significant interest in the industrial production of 1,3,5trioxane.Experimental data for the VLE of quinary systems(formaldehyde+1,3,5...The salt effect on the vaporliquid phase equilibrium(VLE)of solvent mixtures is of significant interest in the industrial production of 1,3,5trioxane.Experimental data for the VLE of quinary systems(formaldehyde+1,3,5trioxane+methanol+salt+water)and their ternary subsystems(formaldehyde+salt+water),(1,3,5trioxane+salt+water),and(methanol+salt+water)were systematic measured under atmospheric pressure.The salts considered included KBr,NaNO_(3),and CaCl_(2).The extended UNIFAC model was used to describe the VLE of the saltcontaining reactive mixtures.The model parameters were determined from the experimental VLE data of ternary systems or obtained from the literature,and then were used to predict the VLE of systems(1,3,5trioxane+KBr+water),(methanol+KBr+water),(formaldehyde+KBr+water),and(formaldehyde+1,3,5trioxane+methanol+salt+water)with salt=KBr,NaNO_(3),and CaCl_(2).The predicted results showed good agreements with the measured results.Furthermore,the model was used to uncover the salt effect on the VLE of these multisolvent reactive systems.展开更多
An experimental system for measuring the VLE of polymer solutions based on the staticvapor-pressure method has been established,VLE data for mixtures of toluene and polystyrene withdifferent molecular weight covering ...An experimental system for measuring the VLE of polymer solutions based on the staticvapor-pressure method has been established,VLE data for mixtures of toluene and polystyrene withdifferent molecular weight covering a wide range from 2.98×10~3 to 3.84×10~6 were obtained at 35℃.The reduced pressure p/p°versus weight fraction W plot is found to be independent on the molecularweight of the polymer within the experimental error.Calculated activity coefficients are also independenton the molecular weight.However,for the Flory-Huggins interaction parameter x,not only a strongconcentration dependence is observed,but also the molecular weight of the polymer exerts definiteinfluence.Generally,the parameter x slightly increases as the molecular weight of the polymer decreasesespecially when the molecular weight is low.The dependence of the parameter x on the molecularweight can be neglected when the molecular weight of polymer is greater than 1.00×10~4.展开更多
Vapor-liquid equilibria for water+hydrochloric acid+magnesium chloride and water+hydrochloric acid+calcium chloride systems at atmospheric pressure were measured using a Othmer-type equilibrium still. The experimental...Vapor-liquid equilibria for water+hydrochloric acid+magnesium chloride and water+hydrochloric acid+calcium chloride systems at atmospheric pressure were measured using a Othmer-type equilibrium still. The experimental data are correlated using a modified Meissner’s method. Satisfactory agreements are obtained between the experimental and the calculated results.展开更多
The aim of this work is to apply cubic equations of state(EOS)to vapor-liquid equilibriacalculations of gas-heavy hydrocarbon systems,which are asymmetric in molecular size and areusually found in natural gases.Invest...The aim of this work is to apply cubic equations of state(EOS)to vapor-liquid equilibriacalculations of gas-heavy hydrocarbon systems,which are asymmetric in molecular size and areusually found in natural gases.Investigation has been done to test the validity of the original PSRKand the cubic simplified perturbed hard-chain(CSPhC)models for global phase diagrams.Thecalculation results show that both equations overpredict vapor pressure in the near critical region.In the prediction of the solubilities of high molecular weight(MW)hydrocarbons in the naturalgas,the PSRK model gives good agreement for the dew point pressure-vapor composition diagrams.Adjustment of the pure component parameters of the CSPHC EOS for heavy components to fit thevapor-liquid equilibrium(VLE)data has been proved to give significant promoting in predictionaccuracy.However,further improvement of a van der Waals EOS,such as SRK,PT and DG modelsfor the asymmetric systems by adjusting the three pure component properties,T_c, p_c and ?展开更多
A new excess Gibbs free energy/equation of state type mixing 0rule was derived byremoving the infinite pressure boundary condition imposed by Wong and Sandler.The mixing rulewas extensively tested in terms of a compre...A new excess Gibbs free energy/equation of state type mixing 0rule was derived byremoving the infinite pressure boundary condition imposed by Wong and Sandler.The mixing rulewas extensively tested in terms of a comprehensive data base,consisting of 52 simple nonpolar-nonpolar,carbon dioxide containing,hydrocarbon-hydrocarbon,CFC,polar-polar,nonpolar-polarbinary and multicomponent systems.Focused on the complete predictive capability,a comparisonbetween the Wong-Sandler and the mixing rule proposed was conducted.The results indicate that thenew mixing rule is in general superior to the Wong-Sandler’s,and the binary interaction parameteras required by the latter is removed,which reduces computing effort and is reliable in predictions ofvapor-liquid equilibria from low pressures to high pressures.展开更多
The Soave[1]equation of state is extensively accepted because of its accuracy andsimplicity.In 1988,Tan et al.[2]suggested a modification by introducing atemperature-dependent factor to parameter"b"on the ba...The Soave[1]equation of state is extensively accepted because of its accuracy andsimplicity.In 1988,Tan et al.[2]suggested a modification by introducing atemperature-dependent factor to parameter"b"on the basis of statistical meaning,anda good accuracy was obtained for supercritical fluids as well as fluids approaching criti-cal conditions but not for mixtures.In the previous work,an extended Soave equa-tion of state[3]has been proposed to improve the prediction of liquid density.In thispaper,the extended equation is used to calculate vapor-liquid equilibria of mixtures atsubcritical conditions.展开更多
Octane and p-xylene are common components in crude gasoline,so their separation process is very important in petroleum industry.The azeotrope and near azeotrope are often separated by extractive distillation in indust...Octane and p-xylene are common components in crude gasoline,so their separation process is very important in petroleum industry.The azeotrope and near azeotrope are often separated by extractive distillation in industry,which can realize the recovery and utilization of resources.In this work,the vapor–liquid equilibrium experiment was used to obtain the vapor–liquid equilibrium properties of the difficult separation system,and on this basis,the solvent extraction mechanism was studied.The mechanism of solvent separation plays a guiding role in selecting suitable solvents for industrial separation.The interaction energy,bond length and charge density distribution of p-xylene with solvent are calculated by quantum chemistry method.The quantum chemistry calculation results and experiment results showed that N-formylmorpholine is the best solvent among the alternative solvents in the work.This work provides an effective and complete solvent screening process from phase equilibrium experiments to quantum chemical calculation.An extractive distillation simulation process with N-formylmorpholine as solvent is designed to separate octane and p-xylene.In addition,the feasibility and effectiveness of the intensified vapor recompression assisted extraction distillation are also discussed.In the extractive distillation process,the vapor recompression-assisted extraction distillation process is globally optimal.Compared with basic process,the total annual cost can be reduced by 43.2%.This study provides theoretical guidance for extractive distillation separation technology and solvent selection.展开更多
Vapor pressures were measured for six binary systems containing water, ethanol, or methanol with one of the two ionic liquids(ILs) at different component concentrations and temperatures using a quasi-static ebulliomet...Vapor pressures were measured for six binary systems containing water, ethanol, or methanol with one of the two ionic liquids(ILs) at different component concentrations and temperatures using a quasi-static ebulliometer,with the ILs mono-ethanolammonium formate([HMEA][HCOO]) and di-ethanolammonium formate([HDEA][HCOO]).The vapor pressures of the IL-containing binary systems are well correlated using the NRTL model with an overall average absolute relative deviation(AARD) of 0.0062. The effect of ILs on the vapor pressure depression of solvents at 0.050 mole fraction of IL is that [HDEA][HCOO]>[HMEA][HCOO], and the vapor pressure lowering degree follows the order of water>methanol>ethanol. Further, the activity coefficients of three solvents(viz. water,ethanol, and methanol) for the binary systems {solvent(1) + IL(2)} predicted based on the fitted NRTL parameters at T 333.15 K indicate that the two ILs generate a negative deviation from Raoult's law for water and methanol and a positive deviation for ethanol to a varying degree, change the relative volatility of a solvent. [HMEA][HCOO]may be a promising entrainer to efficiently separate ethanol aqueous solutions by special rectification.展开更多
基金supported by the National Key R&D Program of China(2018YFB0605804)the National Natural Science Foundation of China(21606237)+2 种基金the Transformational Technologies for Clean Energy and Demonstration,Strategic Priority Research Program of the Chinese Academy of Sciences(XDA 21030500)the Fund of State Key Laboratory of Multiphase Complex Systems,IPE,CAS(MPCS-2019-A-02)the DNL Cooperation Fund,CAS(DNL180202)。
文摘The separation of methanol(MeOH)and dimethyl carbonate(DMC)is important but difficult due to the formation of an azeotropic mixture.In this work,isobaric vapor–liquid equilibrium(VLE)data for the ternary systems containing different imidazolium–based ionic liquids(ILs),i.e.MeOH+DMC+1-butyl-3-methy-limidazolium bis[(trifluoromethyl)sulfonyl]imide([Bmim][Tf2N]),MeOH+DMC+1-ethyl-3-methyl-imidazolium bis[(trifluoromethyl)sulfonyl]imide([Emim][Tf2N]),and MeOH+DMC+1-ethyl-3-methylimidazolium hexafluorophosphate([Emim][PF6])were measured at 101.3 kPa.The mole fraction of IL was varied from0.05 to 0.20.The experimental data were correlated with the NRTL and Wilson equations,respectively.The results show that imidazolium-based ILs were beneficial to improve the relative volatility of MeOH to DMC,and[Bmim][Tf2 N]showed a much more excellent performance on the activity coefficient of MeOH.The interaction energies of system components were calculated using Gaussian program,and the effects of cation and anion on the separation coefficient of the azeotropic system were discussed.
基金The authors gratefully acknowledge financial support from the National Natural Science Foundation of China(grant numbers 22078355,21890763 and 21776300)Petrochemical Research Institute of PetroChina(grant number HX20200668)Scientific Research Project of Ordos Institute of Technology(grant numbers KYYB2019006).
文摘The salt effect on the vaporliquid phase equilibrium(VLE)of solvent mixtures is of significant interest in the industrial production of 1,3,5trioxane.Experimental data for the VLE of quinary systems(formaldehyde+1,3,5trioxane+methanol+salt+water)and their ternary subsystems(formaldehyde+salt+water),(1,3,5trioxane+salt+water),and(methanol+salt+water)were systematic measured under atmospheric pressure.The salts considered included KBr,NaNO_(3),and CaCl_(2).The extended UNIFAC model was used to describe the VLE of the saltcontaining reactive mixtures.The model parameters were determined from the experimental VLE data of ternary systems or obtained from the literature,and then were used to predict the VLE of systems(1,3,5trioxane+KBr+water),(methanol+KBr+water),(formaldehyde+KBr+water),and(formaldehyde+1,3,5trioxane+methanol+salt+water)with salt=KBr,NaNO_(3),and CaCl_(2).The predicted results showed good agreements with the measured results.Furthermore,the model was used to uncover the salt effect on the VLE of these multisolvent reactive systems.
文摘An experimental system for measuring the VLE of polymer solutions based on the staticvapor-pressure method has been established,VLE data for mixtures of toluene and polystyrene withdifferent molecular weight covering a wide range from 2.98×10~3 to 3.84×10~6 were obtained at 35℃.The reduced pressure p/p°versus weight fraction W plot is found to be independent on the molecularweight of the polymer within the experimental error.Calculated activity coefficients are also independenton the molecular weight.However,for the Flory-Huggins interaction parameter x,not only a strongconcentration dependence is observed,but also the molecular weight of the polymer exerts definiteinfluence.Generally,the parameter x slightly increases as the molecular weight of the polymer decreasesespecially when the molecular weight is low.The dependence of the parameter x on the molecularweight can be neglected when the molecular weight of polymer is greater than 1.00×10~4.
文摘Vapor-liquid equilibria for water+hydrochloric acid+magnesium chloride and water+hydrochloric acid+calcium chloride systems at atmospheric pressure were measured using a Othmer-type equilibrium still. The experimental data are correlated using a modified Meissner’s method. Satisfactory agreements are obtained between the experimental and the calculated results.
基金Supported by the National Natural Science Foundation of China and the DAAD-K-C.Wong Foundation.
文摘The aim of this work is to apply cubic equations of state(EOS)to vapor-liquid equilibriacalculations of gas-heavy hydrocarbon systems,which are asymmetric in molecular size and areusually found in natural gases.Investigation has been done to test the validity of the original PSRKand the cubic simplified perturbed hard-chain(CSPhC)models for global phase diagrams.Thecalculation results show that both equations overpredict vapor pressure in the near critical region.In the prediction of the solubilities of high molecular weight(MW)hydrocarbons in the naturalgas,the PSRK model gives good agreement for the dew point pressure-vapor composition diagrams.Adjustment of the pure component parameters of the CSPHC EOS for heavy components to fit thevapor-liquid equilibrium(VLE)data has been proved to give significant promoting in predictionaccuracy.However,further improvement of a van der Waals EOS,such as SRK,PT and DG modelsfor the asymmetric systems by adjusting the three pure component properties,T_c, p_c and ?
基金Supported by the National Natural Science Foundation of China(No.29676003)and China Petro-chemical.Corporation.
文摘A new excess Gibbs free energy/equation of state type mixing 0rule was derived byremoving the infinite pressure boundary condition imposed by Wong and Sandler.The mixing rulewas extensively tested in terms of a comprehensive data base,consisting of 52 simple nonpolar-nonpolar,carbon dioxide containing,hydrocarbon-hydrocarbon,CFC,polar-polar,nonpolar-polarbinary and multicomponent systems.Focused on the complete predictive capability,a comparisonbetween the Wong-Sandler and the mixing rule proposed was conducted.The results indicate that thenew mixing rule is in general superior to the Wong-Sandler’s,and the binary interaction parameteras required by the latter is removed,which reduces computing effort and is reliable in predictions ofvapor-liquid equilibria from low pressures to high pressures.
文摘The Soave[1]equation of state is extensively accepted because of its accuracy andsimplicity.In 1988,Tan et al.[2]suggested a modification by introducing atemperature-dependent factor to parameter"b"on the basis of statistical meaning,anda good accuracy was obtained for supercritical fluids as well as fluids approaching criti-cal conditions but not for mixtures.In the previous work,an extended Soave equa-tion of state[3]has been proposed to improve the prediction of liquid density.In thispaper,the extended equation is used to calculate vapor-liquid equilibria of mixtures atsubcritical conditions.
基金This work is supported by the National Natural Science Foundation of China(No.21776145)National Natural Science Foundation of China(No.21676152).
文摘Octane and p-xylene are common components in crude gasoline,so their separation process is very important in petroleum industry.The azeotrope and near azeotrope are often separated by extractive distillation in industry,which can realize the recovery and utilization of resources.In this work,the vapor–liquid equilibrium experiment was used to obtain the vapor–liquid equilibrium properties of the difficult separation system,and on this basis,the solvent extraction mechanism was studied.The mechanism of solvent separation plays a guiding role in selecting suitable solvents for industrial separation.The interaction energy,bond length and charge density distribution of p-xylene with solvent are calculated by quantum chemistry method.The quantum chemistry calculation results and experiment results showed that N-formylmorpholine is the best solvent among the alternative solvents in the work.This work provides an effective and complete solvent screening process from phase equilibrium experiments to quantum chemical calculation.An extractive distillation simulation process with N-formylmorpholine as solvent is designed to separate octane and p-xylene.In addition,the feasibility and effectiveness of the intensified vapor recompression assisted extraction distillation are also discussed.In the extractive distillation process,the vapor recompression-assisted extraction distillation process is globally optimal.Compared with basic process,the total annual cost can be reduced by 43.2%.This study provides theoretical guidance for extractive distillation separation technology and solvent selection.
基金Supported by the National Natural Science Foundation of China （21076005） and Research Fund for the Doctoral Program of Higher Education of China （20090010110001）.
文摘Vapor pressures were measured for six binary systems containing water, ethanol, or methanol with one of the two ionic liquids(ILs) at different component concentrations and temperatures using a quasi-static ebulliometer,with the ILs mono-ethanolammonium formate([HMEA][HCOO]) and di-ethanolammonium formate([HDEA][HCOO]).The vapor pressures of the IL-containing binary systems are well correlated using the NRTL model with an overall average absolute relative deviation(AARD) of 0.0062. The effect of ILs on the vapor pressure depression of solvents at 0.050 mole fraction of IL is that [HDEA][HCOO]>[HMEA][HCOO], and the vapor pressure lowering degree follows the order of water>methanol>ethanol. Further, the activity coefficients of three solvents(viz. water,ethanol, and methanol) for the binary systems {solvent(1) + IL(2)} predicted based on the fitted NRTL parameters at T 333.15 K indicate that the two ILs generate a negative deviation from Raoult's law for water and methanol and a positive deviation for ethanol to a varying degree, change the relative volatility of a solvent. [HMEA][HCOO]may be a promising entrainer to efficiently separate ethanol aqueous solutions by special rectification.
