Vapor-liquid Equilibrium Data For The System

VAPOR-LIQUID EQUILIBRIUM DATA FOR THE SYSTEM ACETONE-METHANOL SATURATED WITH SALTS" SHUZO OHE, KIMIHIKO

Ishikazvajima-Harima Research Institute, Vapor-liquid

studied.

equilibrium

data

at atmospheric

pressure

of the

YOKOYAMA, AND SHOICHI

Heavy Industries Yokohama

system : acetone-methanol-salt

NAKAMURA

Co., Ltd.

are

The Salts, Kl, NaCI, MgCI2, CaCI2/ LiCI, and CaBr2 are examined to observe the salt effect

on the acetone-methanol

system.

Effective salts are CaQ2, LiC! and CaBr2, which are more soluble in methanol than Kl, NaCI and MgCh. CaCI2, LiCI and CaBr2 are observed to shift the azeotropic composition from 8O.I to 88.6, 9I-O and 94.O mole /# of acetone, respectively. The salt effect at each infinite dilute concentration of acetone and methanol increases with the increasing solubility of each salt in the rich concentration component.

In general, salts shift azeotropic compositions or eliminate azeotropes. For example, sodium chloride saturated in ethanol-water system shifts the azeotropic

composition from 87 to over 90 mole %ethanol45 and

calcium chloride saturated in the ethanol-water system eliminates the azeotrope25. This salt effect may be used for the separation of azeotropic mixtures. Systems which contain water as one component have

2)

Experimental

method

The salt, being completely non-volatile, appears only in the liquid, hence yielding a system consisting of a two-component vapor phase and a three-component liquid phase. The concentrations of acetone and

been well studied5>9>10), but studies on non-aqueous systems are scarce from the point of salt effect. L.

Belcku studied the effect of calcium chloride on the

acetone-methanol system and reported on a constant concentration of 2.3 moles of salt/mole of solution. J. Proszt

and G. Kollar6)

also

studied

the

effect

of

calcium-chloride and lithium-chloride and reported a constant concentration of 1 mole of salt/liter solution.

on of

In this study, isobaric vapor liquid equilibrium data at atmospheric pressure are reported for the six systems ; acetone-methanol-KI, NaCl, MgCl2 CaCl2, LiCl and CaBr2.

L. Belckl:>

suggested

the

possibility

of

the

elimination of the azeotrope, if the data observed from 0 to 95 mole % acetone were extrapolated to 100 mole %acetone. But, the authors' data show the fact that azeotropic

composition

is only

shifted

from 80.1

to

Apparatus and Method 1) Equilibrium

still

The authors modified further the improved Othmer recirculation still presented by Johnson and Furter4) for salt effect studies. Fig. 1 shows the equilibrium still employed.

Heating is done by a wall electric heater adjusted by a transformer. Two high quality standard thermo-

meters are used for measurement of the boiling-liquid and vapor-phase temperatures.

Fig.

Equilibrium

still 1

Received on December 2, 1967 VOL.2

NO.1

1969

methanol in the equilibrium liquid phase were calculated by mass balance, using the concentration of

acetone and methanol in the original charge, and the analyzed concentrations of acetone and methanol in the equilibrium vapor condensate samples. The holdup in the vapor phase chamber and condenser was neglected. Only the equilibrium vapor condensate samples were analyzed. Salt concentrations were calculated by the original charge of each component, which had been weighed. The saturation with salt

was attained with slight excess of solid salt persisting

Fig. 2 x-ycurvesofacetone CaCh system at I atm.

(I)-methanol

(2)-

in the still. The excess solid of salt in the liquid phase was observed from the windowof the still. Twelve runs of measurement were made using the binary system acetone-methanol at atmospheric pressure, in order to check the accuracy of data obtained from the still. The results without salt were compared with the literature data8) and found to be consistent with the data, within the maximumerror of 1%. Thermodynamic consistency of the data was tested by Herington's3) method, and the data of the system without salt were shown to be consistent thermodynamically. The method, however, cannot be applied to the system containing salt, thus the consistency was not tested. To avoid change of salt concentration in the boiling chamber owing to the deposit of salt on the inner wall of the still, the revolution rate of the magnetic stirrer and the distillation rate were adjusted

carefully by continuous observation from the window

of the still. 3) Materials

Acetone, methanol and salts used for experiments were guaranteed 4) Analysis

reagents.

Analysis of the vapor condensate samples was made Fig. 3 saturated

x-y curves of acetone (l)-methanol (2) with LiCI, CaBr2 and CaCh at I atm.

by refractive indices. The refractive indices of acetone and methanol at 20°C are, respectively, 1.3587 and 1.3920.

The difference

in value

of these components

is 0.0333, which is sufficient to determine the concentrations. Compositions were calculated from the tables of refractive

index for the acetone-methanol

system

published in Timmermans8) data-book, with the tabulated data plotted on a large scale. The refractometer employed was an Abbe type. Results All liquid shown effect listed

data are reported on a salt-free basis. Vapor equilibrium data at atmospheric pressure are in Figs.2, 3, 4, and Tables1,2,3. The salt of six salts on the azeotropic composition are in Table 15).

The data for acetone-methanol-calcium-chloride

are

plotted in Fig. 2 and listed as smoothed values in Table 2. Relative volatility of acetone to methanol increases with

increasing

CaCL concentrations

at liquid

phase

concentrations from 0 to 90.0 mole % acetone, but decreases from 90.0 to 100 mole %acetone. (Fig. 4) Fig. 4 (I)-methanol

Relation of relative volatility of acetone (2)-salts system at I atm.

CaCl2, LiCl and CaBr2 are observed to shift the azeotropic composition from 80.1 to 88.6, 91.0 and 94.0 JOURNAL

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Table

I

Salt

effect

of six saturated

Salt

Salts

salts

on acetone (l)-methanol

(2)

system

Solubility

effect*

Acetone (A)

KI

0.809

NaCl MgCl2 CaCl2 LiCl CaBr2 * Salt saturated ** Mole fraction

0. 0. 0. 0. 0.

Table

(l

atm)

in

Methanol

Solubility

(B)

ratio D

0.811

809 802 802 806 800

2

and solubilities"

at 55°C**

3.00X10"

0.818 0.839 0. 840 0. 908 0. 938

The smoothed

55.6 56.2

0.0027 0.0328 0.0775

0.0005 0.0083 0.0098

57.0 57.1

data of vopor-Iiquid

equilibrium

in acetone

(l)-methanol

(2j-CaC!2

(l

atm)

Concentrations of calcium chloride

10 wt. %

5 wt.:

Xi

*_rc] 0.050 0.100 0.150 0.200 0.300 0.400

0.133 0.227 0.302 0.365 0.467 0.550

'

0.500 0.600 0.700 0.800 0.850 0.900 0.950

X\

3

t[°C] y\ t[°C]

15 wt. %

t[°C]

64.9 63.0 61.7 60.5 58.7

64.4 62.8

61.3 60.1 58.6 57.6 56.6

59.9 58.6 57.6 56.7

0.175 0.312 0.422 0.501 0.600

_

0.659 0. 704

55.9

Vapor-Liquid

equilibrium

data

for Acetone (l)-Methanol

(2)

with

saturated

LiCI

95.2 92.1 89.2

85.1 84.0 78.5 73.1 67.8

0.494 0.600 0.703 0.805 0.890 0.940 0.950 0.982

and CaBnare the most effective at about 20, 50, and 60 mole % acetone, respectively, when the salts are 4)

(l atm)

t re]

yi

63.1

0.868 0.883 0.890 0.899 0.907 0.931 0.932 0.958

(Figs. 2, 3) CaCL, LiCl

and CaBr2

t [°C]

yi

LiCl 0.117 0.232 0.321 0.433 0.515 0.610 0.718 0.818

70.6 65.8 63.4 61.7 59.4 57.9 56.9 56.2 55.8 55.9 55.9 56.1 56.2

0.745 0.790 0.834 0.860 0.883 0.921

55.6

mole % acetone, respectively.

0.050 0.096 0.245 0.351 0.486 0.800 0.902 0.950

60.5 57.8 57.4 57.8 56.5 56.6 56.5

CaBr2 0.164 0.274 0.596 0.718 0.852 0.930 0.938 0.948

82.8 86.2 77.9 69.0 62.8 57.1 56.6 56.4

concentrations, the effect is LiCl>CaCl2>CaBr2. acetone-rich concentrations, the effect is CaBr2>LiCl

At

>CaCl2. Saturated salt concentrations were not determined directly. Approximate solubilities, however, are available

Discussion

__

64.8 63.0 61.6 60.5 58.8

56.0

tC°c]

(Fig.

0.148 0.251 0.373 0.459 0.580

57.6 __

yi

0.025 0.050 0.075 0.096 0.129 0.179 0.245 0.359

Saturated

^i

LiCl

saturated.

20 wt. %

yi yi

63.6 61.9 60.8

0.628 0.694 0.765 0.835 -

Table

t[°C]

from x-y curves of each concentration

of

salt. In Fig. 2, the x-y curves of constant salt concentrations: 5, 10, 15wt. % intersect the x-y curve of

of Results

Generally, the salt effect may be predicted by the

solubility of salt in each component. If the salt is more soluble in a less volatile component, then the

relative volatility will be raised, because of the lowered vapor pressure of the less volatile component. In this case, the salts are more soluble in methanol, the less volatile component, thus increasing relative volatility. (Table 1) On the other hand, the salt effect increases with increasing solubility ratio of salt in acetone to methanol

salt

saturated.

The salt concentration

at each inter-

sected point must be the same as that of the respective constant solubilities

salt concentration x-y curve. Therefore, are able to be determined, graphically at

each intersected liquid concentration. Solubilities obtained

are as follows : mole % acetone

(salt free 45.8basis) 63.3 78.3

thus

solubility

(weight %) 15.0 10.0 5.0

at the concentration from 60 to 100 mole %acetone.

The effect is CaBr2>LiCl>CaCl2. In addition to this, the salt effect at each infinite dilute concentration of

Acknowledgment

acetone and methanol increases with increasing solubility of salt in the rich component. At methanol-rich

Mitsuho Hirata (Tokyo Metropolitan University) and the sugges-

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The authors acknowledge the continuing guidance of Professor

tions on experiments of Mr. Motoyoshi Hashitani (Tokyo Met-

ropolitan University, Dr. Course)

1)

cited

Belck,

L.:

Chem.

Ingr.

Techn.,

23,

90

(1951)

2) {Chem. Hashitani,Eng. M., M. Hirata, & Y. Hirose: Kagaku Kogaku Japan), 32, 182 (1968)

Nomenclature

3) Hala, E., et al. : "Vapour Liquid Equilibrium",

D = percentage deviation = the value of log (71/V2) dxi

Press (1958)

:

where?i and j2 are activity a function of boiling points

J

Literature

4) Johnson,

A. L, & W. F. Furter:

(1957)

coeff.

Can. J. Technol.,

Pergamon

34, 413

5) Landolt-Bornstein Zahlenwerte und Funktionen aus Physik. Chemie. Astronomic Geophysik und Technik 2. Teil b (1962) 6) (1966) Meranda, D. & W. F. Furter: Can. J. Technol., 44, 298

Tnim = the lowest measured temperature [°K] x\, xi = mole fractions of acetone & methanol in liquid phase,

7) Proszt, J. & G. Kollar: Roczen. Chem., 32, 611 (1958) 8) Timmermans, J. : "The Physico-Chemical Constants of Binary Systems in Concentrated Solutions" Interscience Pub. (1959) 9) Eng. Uchida, S., S. Ogawa, & M. Yamaguchi: Jap. Set. Rev. Sci.y 1, 41 (1950)

respectively (salt free basis) yi, j/2 = mole fractions of acetone & methanol in vapor phase, respectively (salt free basis) a = relative volatility of acetone to methanol as = relative volatility salt free basis including salt 0 = a function of boiling points = a function of log (7-1/7*2)
10)16, Yamamoto, Y. et al. : Kagaku Kikai {Chem. Eng. Japan), 166 (1952) ll) 28, Yoshida, F. et al. : Kagaku Kogaku {Chem. Eng. Japan), 133 (1964)

VAPOR-LIQUID EQUILIBRIA OF BINARY SYSTEMS CONTAINING ALCOHOLS : ETHANOL WITH NITROMETHANE AND DIETHYLAMINE* KOICHIRO

NAKANISHl*2

RITSUJI

TOBA*3 AND HIDEKO SHIRAl*4

Department of Industrial Chemistry, Shinshu University, Wakasato, Nagano-shi Vapor-liquid

equilibrium

and ethanol-diethylamine between hydroxyl the idea! solution

deviation. results ethanol

data are reported for the

binary

systems

ethanol-nitromethane

(MeNO2)

(Et2NH) at 73OmmHg.As expected from a strong hydrogen-bond interaction

group and amino base, the ethanol-Et2NH system shows negative deviation from law and no azeotrope can be found. The ethano!-MeNO2 system shows a positive

MeNO2forms an azeotrope at 76.4°C and 75.0 mole % of ethanol. Based on these

and other activity coefficient data available, the prediction of azeotrope3 formation solutions by the previously presented correlation and azeotrope diagram is discussed.

In a series of studies on the vapor-liquid equilibria of binary solutions,^12'1" we have obtained the equi-

librium data for ten binary methanol solutions. We

in binary

direction of the deviation from the ideal solution law, is primarily dependent on the proton accepting ability of the

molecule

in alcohol

solution.

However, the

have also proposed a correlation between the limiting value of the activity coefficient of various liquids in

value of the activity

a large excess of methanol, log?"0, and the "hydrogen-

It is thus necessary to obtain detailed information on such size effect for the purpose of establishing a gene-

bond shift" of the stretching bond of methanol in these

vibration of the O-H liquids, Jvs.12^ It was

demonstrated in these studies that the sign and magnitude of the activity coefficient, i. e., the degree and

Received on April 30, 1968 Presented in partEngineers, at the 1stJapan,autumn meeting, Osaka, the Society of Chemical Toyonaka, Nov. 1967

To whomcorrespondence should be addressed to Department of Industrial Chemistry, Kyoto University, Kyoto Present address : Hitachi Seisakusho Co. Ltd.,of Tokyo. Present address: The Tokyo College Pharmacy, Tokyo

coefficient

is also affected by the

in size and shape of component molecules.

ralized activity other associated

coefficient correlation solutions. Although

in alcoholic and a survey of the

literature indicates that, in contrast with binary methanol systems, both isobaric and isothermal vapor-liquid equilibrium data are widely available for binary ethanol solutions, some important information as to the activity coefficient behavior in the ethanol systems is still missing.

In this paper, wewill report the barometric vaporliquid equilibrium data of ethanol (EtOH) with nitromethane

(MeNCh)

and

with

diethylamine

(Et2NH).

4

Shinjuku,

difference

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