| US 7,501,047 B2 | ||
| Method for purifying caprolactam | ||
| Hermann Luyken, Ludwigshafen (Germany); Andreas Ansmann, Wiesloch (Germany); Christoph Benisch, Mannheim (Germany); Peter Baβler, Viernheim (Germany); Rolf-Hartmuth Fischer, Heidelberg (Germany); Stefan Maixner, Schwetzingen (Germany); and Johann-Peter Melder, Böhl-Iggelheim (Germany) | ||
| Assigned to BASF Aktiengesellschaft, Ludwigshafen (Germany) | ||
| Appl. No. 10/534,822 PCT Filed Nov. 11, 2003, PCT No. PCT/EP03/12558 § 371(c)(1), (2), (4) Date May 13, 2005, PCT Pub. No. WO2004/043915, PCT Pub. Date May 27, 2004. |
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| Claims priority of application No. 102 53 094 (DE), filed on Nov. 13, 2002. | ||
| Prior Publication US 2006/0090994 A1, May 04, 2006 | ||
| Int. Cl. B01D 3/14 (2006.01); B01D 3/34 (2006.01); C07D 201/08 (2006.01); C07D 201/16 (2006.01) | ||
| U.S. Cl. 203—35 [203/75; 203/77; 540/540] | 16 Claims |
| 1. A process for purifying crude caprolactam comprising
1) converting a mixture (I) comprising 6-aminocapronitrile and water to a mixture (II) comprising caprolactam, ammonia, water,
high boilers and low boilers in the presence of a catalyst,
2) removing ammonia from the mixture (II) to obtain a mixture (III) comprising caprolactam, water, high boilers and low boilers,
3) completely or partly removing water from the mixture (III) to obtain crude caprolactam (IV) comprising caprolactam, high
boilers and low boilers, and
4) distilling the crude caprolactam (IV) comprising
a) feeding the crude caprolactam (IV) and an inorganic acid which has a boiling point above the boiling point of caprolactam
to a first distillation apparatus C1,
b) distilling the crude caprolactam IV and the inorganic acid in the first distillation apparatus C1, and removing a first substream in the bottom region and a second substream in the top region of the distillation apparatus
C1,
c) feeding the second substream from step b) to a second distillation apparatus C2,
d) distilling the second substream from step b) in the second distillation apparatus C2, and removing a first substream in the bottom region and a second substream in the top region of the distillation apparatus
C2,
e) feeding the first substream from step d) to a third distillation apparatus C3,
f) distilling the first substream from d) in the third distillation apparatus C3, and removing a first substream in the bottom region of distillation apparatus C3 and removing purified caprolactam in the top region of distillation apparatus C3, and
g) feeding the first substream from step f) to the first distillation apparatus C1.
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