WOLFRAM|DEMONSTRATIONS PROJECT

Extractive Distillation Column to Separate Isopropyl Alcohol from Water

​
reflux ratio R
2.
reboil ratio s
0.52
The binary mixture of water and isopropyl alcohol (isopropanol or propan-2-ol) presents a positive azeotrope at 1 atm. This azeotrope contains
69.8
mole % isopropanol. It is possible to break this azeotrope using extractive distillation. Possible entrainers include: (1) 1,2-ethanediol or ethylene glycol, (2) DSMO (or dimethyl sulfoxide), (3)
N
-methyl-2-pyrrolidone or NMP, (4)
N
-methyl-2-piperidone, and (5)
N
-methyl-6-caprolactam.
In this Demonstration, DSMO is used as an entrainer in an extractive distillation column. The column has 41 plates, a partial reboiler, and a total condenser. This column has an upper feed entering the column at plate 5 and containing pure DSMO with a flow rate of 1708 mol/min. The column has also a lower feed entering the column at plate 25 and containing
30%
mole isopropanol and
70%
mole water. This lower feed has a flow rate of 1666 mol/min. You can set the reflux and reboil ratios,
R
and
s
. For
R=2
and
s=0.52
, the distillate obtained is almost pure isopropanol (
99.6
mole %) and the bottom is a mixture of water
(40.48
mole %) and DSMO
(59.39
mole %), which can be easily separated in a second distillation column—the entrainer regeneration column.