I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
2392
PROCEDURE AND RESULTS
Solutione of ethyl alcohol and n-heptane or TTater m,ere prepared, and enough of the the third component was added to produce a cloud point. T h e solutions were made Up by weight, using an analytical balance. The samples were held a t 30.0" =t0.03" C. in a constant-temperature bath, and r ~ e r removed e only for short periods to add the third component. Density and refractive index 1neasurementP w r e made on tlic samples a t the cloud point. The immiscibility curve for the ethyl alcohol-n-heptanewater system is shown in Figure 1. The data are given in Table I. T h e tie lines shown in this figure are for even percentages of water in the water-rich layer. The end compositions were taken from the correlation shown in Figure 3. Densities were measured with a 5-ml. pycnometer, calibrated a t 30" C. The ;Tide and regular variation of density with composition makes i t especially useful in the analysis of the ternary solutions (Figure 2 ) . Density measurements were used for all analyses. The refractive index data were not used, but are included in Table I as an additional means of analysis.
Vol. 46, No. 11
Tie-line data were determined by analyzing the two liquid phases of ternary mixtures. The two-phase mixtures were placed in a constant temperature bath a t 30.0" j=0.03" C. and agitatcd periodically. The t r y 0 phases were then separated and each 1 ~ analyzed by utilizing the density-composition relation of Figure 2. The experimental results shown in Table I correlate by a method suggested by Uachman ( 1 ) (Figure 3). LITERATURE CITED (I) Bachman. I., IKD. E s o . CHXM..AYAI..ED.,12, 38-9 (1940:. ( 2 ) Bonner, W, D., J . Phys. Chem., 14, 738-89 (1910).
(3) Ormandy, W.R., and Craven, E. C., J . Inst. PetroZeum Teci~iiol, 8, 181-93 (1922). (4) Schweppe. J. L., "Use of n-Heptane in the Preparation of
Absolute Alcohol," 11.6. thesis, University of Ilissouri, 1946. (5) Reidell, A , "Solubilities of Organic Compounds," Vol. 11, 3rd ed., pp. 147, 148, 562. D. Van Kostrand Co., New York. 1$131: Supplemental Volume, pp. 931, 932, 1048, 1952. RECEIVED for reviev hlarcl, 30, 1954,
Vapor-Liquid Equilibria of Alcohol-Water System at S
AccsPrEn June 11, 1O:L.
Diacetone I
Pressures C. 'iY. HACK' AND IIATTHEW VAN WIKKLE C n i v e r s i t ) of Texas, dustin 12, T e n ,
111; use of diacetone alcohol as a solvent for the separation of certain hydrocarbon mixtures has been investigated. Commonlg- the alcohol is separated from t,he hydrocarbon phase by Tvater extraction and the alcohol and x-ater are separat,ed by distillat,ion. Because of minimum boiling azeotrope in the diacetorie alcohol-iTater system has been reported ( 8j a t atmospheric pressure, this investigation \?as initiated t o det,erinine the possibility of breaking the azeotrope b y lowering t'he sycltem preasure.
The diacetone alcohol \vas thermally unstable, particu1:irly a t temperat,ures above 140' C., when heated for short periods of time. Because of this t'he purification mas carried on a t a much lorver temperature by distilling under vacuum. The diacetone alcohol as stored at 40' F. and frequent checks of refractive index were made to ensure that no changes were occurring in the sample. The water used in the investigation was distilled water, boiled
BIATERI.4LS
The diacetone alcohol used in this investigation was obtained as a commercial grade containing approximately 157, acetone. I t was redistilled three times a t 20 nun. of mercury pressure and the middle 807, of the material n-as retained each t,ime. The last heart cut showed no change in refractive index or boiling point on further distillat,ion. The properties of the purified compound are shown in Table I.
E TABLE I. P R O P E R T I OEFSD I A C E T O NALCOHOL Experimental Refractive index,
nko
O
Boiling point, 760 mm.,
C.
1.42861 C.
168.1
Vapor pressure, Log10 P = 8 082 Antoine equation where P = mm. Hg, t = a I;.
Literaiiire 1,4233 (6) 1.4232 ( S j 169.1 (1) 1 6 7 . 9 18)
3888 -~ _ 414 + t o F.
_
T h e vapor pressuretemperature data were determined esperimentally in the Colburn still and the hntoine constants were derived from the data. These data agree within i1%with those reported by Gardner (3).
*
Present address, Holloman .4ir Force Base New Mexico.
0
IO
20
30
WEIGHT
Figure
40
50
60
70
80
90
100
PERCENT W A T E R I N LIQUID. X
1. Vapor-Liquid Equilibrium Diagram for Diacetone Alcohol-Water System
~
s
November 1954
INDUSTRIAL AND ENGINEERING CHEMISTRY
2393
a Bausch and Lomb Precision refractometer using a monochromatic sodium d line light source. PROCEDURE
A modified Colburn ( 4 ) equilibrium still was used t o obtain the vapor-liquid equilibrium data. The modificatioiis and general procedure have been reported ( 7 ) . T h e still was operated under steady state conditions of constant liquid levels, constant temperature, and coristant pressure for periods of time not exceeding 45 minutes before equilibrium samples were taken. This was done to prevent decomposition of the diacetone alcohol. If there were any changes in observed temperature during this period, the run was discarded arid a new run was made. RESULTS
MOLE PERCENT WATER IN LlPUlo
0
Ib
20
30
40
50
60
70
80
90
100
MOLE PERCENT WATER IN LlWlD
Vapor-liquid equilibrium data were obtained for the diacetone alcohol-water system a t pressures of 400, 200, 100, and 50 mm. of mercury pressure and partial data were determined a t 760 mm. of mercury pressure. Experimental activity coefficients were calculated from the data by
Figure 2. Vapor-Liquid Equilibrium Diagram for Diacetone ..llcohol-Water System Gas law deviation factors (compressibilities) were not included in evaluation of the activitj coefficients. Although these deviations may be appreciable, lack of necessary knowledge of critical properties of diacetone alcohol prevented quantitative evaluation of this effect. Table I1 includes the temperature, equilibrium vapor and liquid compositions, and the calculated activity coefficients. Figure 1 presents the temperature-composition relations on a weight per cent basis and Figure 2 on a mole per cent basis. Figures 3 and 4 present the equilibrium vapor-liquid composition data on a weight per cent and mole per rent basis, respectively.
1
b
160 -
I
j
150
0
IO
20
30
40
50
60
70
80
90
100
WEIGHT PERCENT WATER
Figure 3.
Equilibrium Boiling Point Diagram for Diacetone Alcohol-Water System
to dispel dissolved gases. The experimental refractive index of 1.3330 a t 20' C. checked exactly that reported by Lange ( 5 ) . ANALYTICAL PROCEDURE
Boiling points were determined in the Colburn still, which was provided with controls to maintain the various subatmospheric pressure. Temperatures were measured by means of a calibrated thermocouple in conjunction with a Leeds and Northrup Precision potentiometer. Refractive index measurements were made u-ith
0
10
20
30
40 IvIOl.E
Figure 4.
50
60
70
80
90
100
P E R C E L T WATER
Equilibrium Boiling Point Diagram for Diacetone Alcohol-Water System
Vol. 46, No. 11
I N D U S T R I A L A N D E N G I N E E R I N G CHEMISTRY
2394
EQUILIBRIUM DATAFOR DIACETONE TABLE 11. VAPOR-LIQUID ,kLCOHOL-~~'ATER SYSTElI
'remp.,
F.
Temp.,
c.
x
DAA,
Kater,
J
Y
/
4.7 7.7 12.2 14.8 15.8 17.2 21.1 23.7 28.7 32.2 38.5 48.8 48.8
18. 15.1 11.3 10.5 9.83 8.06 4.95 3.91 3.08 2.63 2.0s 1,53 1.50
1.01 1.01 1.01 1.02 1.02 1,02 1,05 1.08 1.14 1.20 1.38 1.57 1,63
211.6 211.5 211.5 211.1 211.1 211.5 211.8 212.0 212.4 213.3 216.0 228.4 228,4
99.75 99.70 99.70 99,50 99.50 99.70 99,90 100.00 100.20 100.70 102.20 109.10 109.10
0.39 0.82 1,82 2.46 2.85 3.78 7.83 11.42 18.37 24.62 38.88 59.64 61.06
700 Llm. H g 0.76 2,5 1.28 5.1 2.11 10.7 2.62 14.0 2.83 15.9 3.12 20.2 3.98 35.4 4.60 45.4 5 88 59.2 6.86 67.8 8.85 80 4 12 88 90.2 12.88 91.0
181.0 180.9 180.9 180,7 181.1 181.0 181.6 182.0 182.9 185,O 188.0 196.2 212.9 228.0
82.75 82,70 82.70 82.60 82.80 82.78 83.10 83.30 83.80 86.75 91.2 100 5 108.9
0.40 0.Y8 1.62 1.88 3.86 7.77 11.92 17.82 25.40 34.69 45.25 61. 63 80,60 89.97
400 M m . Hg 0 52 2.5 1.10 6.0 1.64 9.6 1.84 11.0 2.81 20.5 3.62 35.2 4.19 46.6 4.69 58,3 5.71 68.7 6.71 77.4 8.35 84.2 11.55 91.2 18 ti8 96.4 26.21 98.3
3.2 6.7 9 7 10.8 15.7 19.5 22.0 24.1 28.1 31.7 37.0 45,7 59.9 69.6
14.0 12.3 11.1 10.7 7.97 5.09 3.78 2.79 2.34 1.91 1.68 1.37 1.15 1,04
1.01 1.01 1.01 1.02 1.02 1.05 1.08 1,14 1.24 1.32 1.42 1.68 2.17 2.85
151.5 151.5 151.4 151. ii 132.0 151.8 1.52 1 152.2 1.52 2 163.3 153.6 153.6 155.0 155.8 ls3,5 166 5 liG 9 209.2
66.45 66.45 66 40 60.5 66.70 66 76 66.75 66.80 66.80 67.30 6 7 . GO 67 50 68 24 !3,8.72 ,0.20 74,iO 80.40 98.4
0.23 0.27 0.48 0 54 1 03 1.64 3 55 6 04 8.8: 13 76 19.99 23.78 29.02 34.05 40.43 i9.64 13.10 73.89
200 hIm. I-lg 0.25 1.5 0.27 1.7 0.52 3.0 0.53 3 4 0.93 6.3 1.30 9.7 2.07 19.2 2.82 20.3 3.30 38,5 3.68 50.7 4 15 61.7 4.38 66.8 4 87 72.5 5.40 76.9 5.PO 81 4 9.48 90.5 13.76 94.6 35.79 99.0
1.6 1.7 3.2 3.3 5.7 7.8 12.0 15.8 18.3 19.7 21.8 22.8 24.8 27.2 28.8 40 3 50 7 7k2
13.1 12.6 11 5 11.8 10 9 9 64 7.02 5.61 4 5G 3.13 2.4s 2.14 1.86 1.75 1.46 1.27 LO5 1.03
1 00 1.00 1.00 1.00 1.00 1.00 1.00 1 03 1.04 1.08 1.14 1.20 1.24 1.30 1.34 1 . 57 1.98 2.93
9.94 11.1 8.35 7.33 5.07 3 95 2.58 2.18 1.78 1.60 1 53 1.12
1.00 1.00 1.00 1.01 1.03 1.07 1.16 1.20 1.35 1.52 1.81 3.16
10.3 7.51 6.70 5.33 4.18 3.13 2.33 2.04 1.74 1,50 1.20 1.04
1.00 1.01 1.02 1 02 1.03 1.08 1.19 1.34 1.40 1.80 2.53 3.10
85,OO
100 h l m . Hg 124.9 125.1 125.1 125.2 125.8 125.9 126.1 127.6 128.7 132,s 138.5 164.1
51.60 51.70 51.70 51.75 52 18 5 2 . 18 52.30 53.10 53.70 55.80 59.20 73.40
0.17 0.44 2.11 4.12 8.02 12.01 20.19 2G 20 36,85 50 OB 05.67 91.06
012 030 1 29 2 23 3 01 3 44 3 96 4 50 5 50 7 37 10 07 23 70
1 2 12 21 30 46 62 69 70 86 92 98
0 8 0 6 0 6 5 5
0.8 2.3 7.8 12 8 16.7 18.7 21.0 23.3 27.3 33.9 43.5 68.7
100.9 100.9 101.0 102.0 102.5 103.0 103.5 104 2
38.20 38.21 38.25 38,90 39,20 39.40 39,70 40 20 42.00 45 80 52.80 64.90
0 . '18 2.03 4.26 8.22 ll,59 18.54 25.84 36.57 45.63 66,66 86.32 93.88
0.32 0.98 1.84 2.93 3.29 3.62 4.28 5.37 6.49 10.44 18.25 29.23
2.0 11.8 22.3 36.0 45.8 56.1 69.2 78.8 84.4 92.8 97.6 99.0
3.0 6.0 10.8 16.3 18 0 19.5 22.4 26.8 30.9 42 9 59.0 72.7
107,6 114.2 127.0 148.8
1 8 2
7
Figures 5 and 6 present the "experimental" activity coefficientcomposition data. Only partial data could be determined a t a pressuie of i 6 0 mm. of mercury because of decomposition of the diacetone alcohol at the higher temperatures encountered a t high concenti ations of diacetone alcohol. Azeotropes were found t o exist a t 760, 400, and 200 mm. of mercury pressure. Azeotrope compositions and temperatures are shown in Table I11 and the composition variation v i t h pressure is shown in Figure $. Extrapolation indicates t h a t the azeotrope disappears a t approxiinately 148 mm. of mercury pressure. T h e azeotrope composition of 81.3 weight % water a t 99.5" C. determined in this investigation does not check the
0 20 40 60 80 100 0 20 40 60 80 I00 X - M O L E PERCENT DIACETONE ALCOHOL I N LIQUID
Figure 5. -4cti~ityCoefficients of Diacetone tlcoholWater System @Alcohol
0 X
OWater
10 20 30 40 5 0 60 70 80 90
- MOLE
100
PERCENT DIACETONE ALCOHOL IN LIQUID
Figure 6. Activity Coefficients of Diacetone Alcohol-Water System .Alcohol
OWater
November 1954
INDUSTRIAL AND ENGINEERING CHEMISTRY
2395
i 000
TABLE111. VARIATIONOF AZEOTROPICCOMPOSITIOS PRESSURE FOR DIACETONE ALCOHOL-WATER SYSTEM
900
WITH
800
Water Weight Mole
700 600
%
%
84.3 89.5 96.7
97.19 98.21 99.47
1,
c.
99 50 82.60 66.40
t,
O
E‘.
211.1 180.7
151.4
Pres,
sure 760 400 200
500
Colburn ( 2 )modification of the Van Laar equations. The results did not agree closely, particularly in the region of high alcohol concentration. This could be caused by the thermal instability of the diacetone alcohol a t higher temperatures, the rather wide boiling range of the system even a t 50 mm. of mercury, and the possible deviations of the vapors from ideal gas behavior. A t low concentrations of diacetone alcohol in the region of the azeotrope the experimental data are considered to be most reliable, based upon consistency tests. All of the data, were reproducible within the experimental limits of error and are therefore reported as experimental data without any smoothing. The estimated maximum errors in the experimental values are 0.1’ C. and 1.0 mole %.
OI
*
400
E
J
2
300
u) W
P
2 00
I50
NOMENCLATURE
too
= = = P = PT = y
80
85
90
95
IO0
WEIGHT PERCENT WATER
Figure 7. Change of Azeotrope Composition with Pressure for Diacetone Alcohol and Water
z y
activity coefficient defined by Equation 1 mole fraction in liquid mole fraction in vapor vapor pressure total pressure LITERATURE CITED
(1) Carbide and Carbon Chemicals Corp., New York, “Synthetic
value reported by Shell Chemical Co. (8) of 87.3 weight % water a t 98.8’ C. No azeotropes were observed a t pressures of 100 and 50 mm. of mercury, although the tendency toward azeotrope formation is shown on the temperature-composition plots for those pressures. Examination of the activity coefficient-composition plots in Figures 5 and 6 indicates that this binary system is extremely noiiideal in its behavior. As the pressure is decreased, the deviations from ideality decrease, and this is normally to be expected. Van Laar constants were evaluated for the components a t the various pressure by extrapolation of the experimental -pz curves. These values were used to calculate 7 - 2 data by the Carlson and
Organic Chemicals,” 1951. ( 2 ) Carlson, H. C., and Colburn, A. P., ISD. ENG.CHEM.,34, 581
(1942). (3) Gardner, E., Ibid., 32, 226 (1940). (4) Jones, C., Schoenborn, E., and Colburn, A. P., Ibid., 35, 660
(1943). ( 5 ) Lange, A. H., “Handbook of Chemistry,” 7th ed., Handbook
Publishers, Inc., 1949. (6) Mellan, I., “Industrial Solvents.” p. 610, S e w York, Reinhold
Publishing Corp., 1950.
(7) Rasmussen, R. R., and Van Winkle, II.,IND. ENG.CHZM.,42,
2121 (1950). (8) Shell Chemical Co., Kew York, “Organic Chemicals,” 1950.
RECEIVED for review November 16, lQ53. ACCEPTED M a y 10, 19.54. Abstracted from a thesis submitted in partial fulfillment of the I’equirements for the degree of master of science in chemical engineering.
