ISOBARIC VAPOR-LIQUID EQUILIBRIA FOR THE BINARY
SYSTEM OF 4-METHYL-2-PENTANONE WITH 1-BUTANOL
AT 20 AND 101.3KPA.
Nelson Martíneza, Estela LLadosaa, MaCruz Burgueta, Juan B. Montóna and Marlin Yazimonb
aDepartamento
de Ingeniería Química, ETSE, Universitat de València, 46100 Burjassot, Valencia, España
de genie chimique et genie des procedes, iut A Lyon 1 Lyon France
bDepartament
Introduction
Usually, a mixture of different alcohols with ketones forming azeotropes is very common product. Therefore, the purification of the
ketones and recovery of the alcohols for recycling is usually impracticable by distillation. The separation can be improved making a simple
change in pressure, provided that the azeotropic composition is sensitive to pressure “pressure swing distillation”
In this work it has been studied the binary systems formed for 4-methyl-2-pentanone (MIBK) + 1-butanol at isobaric conditions. at 20
and 101.3 kPa, with the purpose of studying the influence of the pressure in the composition of the azeotropic mixture.
Experimental section
• A dynamic-recirculating still equipped with a Cottrell circulation pump was used in
the equilibrium determinations (Figure 1). The system was kept at the boiling
point for at least 30 min to ensure that the steady state was reached. Then,
samples of liquid and condensate vapor were taken for analysis.
 Compositions of the liquid and condensed vapor phase samples were determined
by gas chromatography.
 The accuracy of experimental measurements was 0.01 K in temperature, 0.1
kPa in pressure, and 0.001 in mole fraction.
Figure 1 Experimental
equipment
1. Immersion heater
2. Cottrell pump
3. Column
4. Mixing chamber
5. Magnetic stirrer
6. Solenoid coil and
valve hood
7. Pt-100 sensor
Experimental results
392
The Experimental data for the binary system are presented in the figure 2 at 20 kPa
and 101.3 kPa and compared with the results found in the literature
We can to observed the strong dependency of azeotropic compositions on pressure
The VLE data presented were found to be thermodynamically consistent using the
Fredenslund test at both pressures.
352
350
P = 20 kPa
P = 101.3 kPa
390
348
T (K)
T (K)
346
388
344
342
386
340
0.0
0.2
0.4
0.6
0.8
1.0
0.0
0.2
0.4
x1, y1
0.6
0.8
1.0
x1, y1
Figure 2.T-x-y diagrams of the system MIBK-1Butanol at 101.3 kPa and 20 kPa Experimental data
(.), Tamir et al [1] (o), Cabezas [2] (∆) and Wilson
model (––)
Thermodynamic Modeling
• The activity coefficients of the solutions were correlated by Wilson, NRTL and UNIQUAC models. The results of this correlation are
shown in Table 1, with the systems formed for methyl isobutyl ketone+ 1-butanol The results show that all models fitted the
experimental data of these systems at both pressures very well.
 The figure 3 show the excess Gibbs energy for the liquid phase at 20 kPa y 101.3 kPa, from which it is concluded that positive
deviations from ideality are present in the liquid phase. Moreover, values for the excess Gibbs energy, decrease as the pressure
increases for a given mol fraction.
Table 1. Correlation of Binary Systems for Different GE Models
500
Aij
(J.mol-1)
Aji
(J.mol-1)
ij
400
AADT b
AADy1a
(K)
Wilson
c
NRTL
300
20
-751.16
2601.23
0.09
0.0025
101.3
-323.39
1666.30
0.05
0.0024
20
1632.50
127.57
0.30
0.08
0.0028
0.30
101.3
1118.87
203.72
0.04
0.0026
20
1297.24
-630.53
0.08
0.0030
101.3
997.46
-505.62
0.04
0.0024
E
G (J/mol)
Model
P
kPa
200
100
0
0.0
UNIQUACd
a
Average absolute deviation in temperature. bAverage absolute deviation in vapor phase composition.. cliquid volumens from
DECHEMA. dvolume and surface parametersfrom DECHEMA
0.2
0.4
0.6
0.8
1.0
x1
Figure3.Excess Gibbs energy
function. P= 101.3kPa (.);
P=20kPa(∆) ;Wilson (__)
Conclusions
Consistent VLE data have been determined for the systems 4-methyl-2-pentanone (1) + 1-butanol (2), at 20 and 101.3 kPa. The
Wilson, NRTL and UNIQUAC models were capable of correlating the data for the binary system.
The equilibrium diagram for 4-methyl-2-pentanone (1) + 1-butanol (2), show that the azeotropic composition is very sensitive to pressure.
Therefore, in view of the results, pressure-swing distillation could be a useful technique in order to overcome the binary azeotrope.
[1] A. Tamir, J. Wisniak, J. Chem. Eng. Data 23 (1978) 293-298
[2] J.L Cabezas, S. Beltran, J. Coca. Private Comunication (1978. From DDBST Software and Separation Technology GmbH
Acknowledgements. Financial support from the Ministerio de Ciencia y Tecnología of Spain, through project CTQ2007-61400/PPQ, FEDER European Program and the Conselleria de
Cultura, Educació i Esport (Generalitat Valenciana) of Valencia (Spain