Coupling of distillative purification with a partial condenser for pre-purification of isophoronediamine
A process for fine purification of isophoronediamine (IPDA), including producing IPDA by aminating hydrogenation of isophorone nitrile in the presence of at least ammonia, hydrogen, a a hydrogenation catalyst and optionally further additions to obtain a crude IPDA, and subjecting the crude IPDA to a fine purification via two vacuum distillation columns, wherein in the first vacuum distillation column the removal of any remaining relatively low-boiling byproducts is effected and in the second vacuum distillation column the IPDA is obtained in pure form as tops and thus separated from the organic residues, and wherein the first vacuum distillation column has vacuum distillation column has a partial condenser fitted to it.
1. A process for fine purification of isophoronediamine (IPDA), pure isophoronediamine, comprising the steps of:
(a) producing isophoronediamine by aminating hydrogenation of isophorone nitrile in the presence of at least ammonia, hydrogen, a hydrogenation catalyst and further additions to obtain a crude isophoronediamine;
(b) distillative removing the ammonia and hydrogen from the isophoronediamine of step (a) to obtain the crude isophoronediamine; and
(c) purifying the crude isophoronediamine of step (b) via a first vacuum distillation column comprising a partial condenser and a vapor stream, and a second vacuum distillation column by distillative removing of isophoronediamine, water, low boilers and high boilers from the crude isophoronediamine to make a fine purification,
wherein the vapor stream is pre-cooled and partly condensed in the partial condenser to form a condensed liquid, which is used as return stream in the first vacuum distillation column, and
wherein the isophoronediamine leaves the first vacuum distillation column as a bottoms stream, wherein the bottoms stream is sent to the second vacuum distillation column wherein high boilers are removed to obtain the purity of the pure isophoronediamine is at least 98 wt % as tops.
2. The process according to claim 1 , wherein the crude isophoronediamine generally comprises the following composition in weight % (wt %) based on the weight of the crude isophoronediamine:
IPDA
75-100
wt %;
Water
0-15
wt %;
Low boilers
0-6
wt %; and
High boilers
0-6
wt %.
3. The process according to claim 2 , wherein the uncondensed vapor stream in the first vacuum distillation column is fully condensed and divided into an organic phase and an aqueous phase in a second condenser, wherein the organic phase is partly used as reflux for the first vacuum distillation column.
4. The process according to claim 2 , wherein IPDA leaves the first vacuum distillation column as bottoms stream and is sent to a second vacuum distillation column for removal of the high boilers.
5. The process according to claim 2 , wherein the pure IPDA is obtained at the top of the second vacuum distillation column.
6. The process according to claim 2 , wherein the partial condenser is operated under the following conditions:
Temperature
40-120° C.; and
Pressure
10-200 mbar.
7. The process according to claim 2 , wherein the employed first vacuum distillation column comprises the following parameters:
Pressure
10-200 mbar;
Bottoms temperature
80-200° C.; and
Theoretical plates
10-80.
8. The process according to claim 1 , wherein the purity of the pure isophoronediamine is at least 99.95 wt %.
9. The process according to claim 1 , wherein the uncondensed vapor stream in the first vacuum distillation column is fully condensed and divided into an organic phase and an aqueous phase in a second condenser, wherein the organic phase is partly used as reflux for the first vacuum distillation column.
10. The process according to claim 1 , wherein IPDA leaves the first vacuum distillation column as bottoms stream and is sent to a second vacuum distillation column for removal of the high boilers.
11. The process according to claim 1 , wherein the pure IPDA is obtained at the top of the second vacuum distillation column.
12. The process according to claim 1 , wherein the partial condenser is operated under the following conditions:
Temperature
40-120° C.; and
Pressure
10-200 mbar.
13. The process according to claim 1 , wherein the employed first vacuum distillation column comprises the following parameters:
Pressure
10-200 mbar;
Bottoms temperature
80-200° C.; and
Theoretical plates
10-80.
14. The process according to claim 1 , wherein the composition of the feed stream from the first vacuum distillation column into the second vacuum distillation column (crude IPDA II) comprises the following composition (wt %) based on the weight of the crude isophoronediamine:
IPDA
90-100
wt %; and
High boilers
0-10
wt %.
15. The process according to claim 1 , wherein the employed second vacuum distillation column comprises the following parameters:
Pressure
10-200 mbar;
Tops temperature
80-200° C.; and
Theoretical plates
5-50.