Method for obtaining crystalline L-alanine

Patent metadata

Field	Value
Publication number	US-9908842-B2
Application number	US-201515501869-A
Country	US
Kind code	B2
Filing date	Aug 7, 2015
Priority date	Aug 8, 2014
Publication date	Mar 6, 2018
Grant date	Mar 6, 2018

Abstract

The present invention relates to a method for obtaining crystalline L-alanine from an aqueous solution of L-alanine, in particular from an aqueous solution of L-alanine, which is obtained from a fermentation process.

First claim

We claim:

1. A method for obtaining crystalline L-alanine from an aqueous solution of L-alanine containing 100 to 30,000 ppm, based on L-alanine, of one or more α-amino acids different from L-alanine, comprising
a) providing an aqueous solution of L-alanine containing at least 100 ppm, based on L-alanine, of one or more α-amino acids different from L-alanine;
b) subjecting the solution of L-alanine to a crystallization by inducing conditions of a controlled supersaturation in a manner that the ratio c:c* of the concentration c of dissolved L-alanine to the equilibrium solubility c* of L-alanine under the conditions of controlled supersaturation is in a range from > 1:1 to 1.5:1, thereby affecting the crystallization of L-alanine; and
c) separating crystalline L-alanine from the mother liquor.
wherein the aqueous solution of L-alanine is fed to a continuously operated crystallization apparatus, which contains an aqueous suspension of L-alanine crystals.

2. The method of claim 1 , where the concentration of dissolved L-alanine under the conditions of supersaturation is from 150 to 400 g/L.

3. The method of claim 1 , where the controlled supersaturation is induced at a temperature of at least 30° C.

4. The method of claim 1 , where the controlled supersaturation is induced by removing water and/or by cooling.

5. The method of claim 4 , where the water is removed by evaporation.

6. The method of claim 1 , where step b) comprises
b1) continuously feeding the aqueous solution of L-alanine to a crystallisation apparatus containing an aqueous suspension of L-alanine;
b2) continuously removing water from the aqueous suspension of L-alanine contained in the crystallisation apparatus to maintain conditions of controlled supersaturation;
b3) continuously removing the aqueous suspension of L-alanine from the crystallisation apparatus.

7. The method of claim 6 , where a portion of the aqueous suspension of L-alanine removed in step b3) is mixed with the aqueous solution of L-alanine of step b1) and the mixture is fed back it into the crystallization apparatus.

8. The method of claim 7 , where the mass ratio of the mixture which is fed back it into the crystallization apparatus and the aqueous solution of L-alanine, mixed with the suspension, is at least 4:1.

9. The method of claim 1 , where the solid content of the aqueous suspension is from 5 to 30% by weight, based on the weight of the suspension.

10. The method of claim 1 , where the crystallization is effected in a crystallizer, selected from a forced circulation crystallizer, draft tube crystallizer, a draft tube baffled crystallizer, an Oslo-type crystallizer, and an induced forced circulation crystallizer.

11. The method of claim 1 , where the crystallization of L-alanine comprises at least two subsequent crystallization steps.

12. The method of claim 11 , where the crystalline L-alanine obtained in a precedent crystallization step is dissolved in a mixture of the mother liquor of the subsequent crystallization step with water to obtain an aqueous solution of L-alanine, from which L-alanine is crystallized in the subsequent crystallization step.

13. The method of claim 1 , where the aqueous solution of L-alanine provided in step a) does not contain more than 100 ppm of solid insoluble material.

14. The method of claim 1 , where the aqueous solution of L-alanine provided in step a) has been filtered to remove solid insoluble material.

15. The method of claim 1 , where the aqueous solution of L-alanine provided in step a) contains at least one amino acid selected from the group consisting of D-alanine, L-valine, L-leucine, L-lysine, L-asparagine, L-glutamine, and L-arginine.

16. The method of claim 1 , where the aqueous solution of L-alanine provided in step a) is obtained by a fermentation process.

17. The method of claim 9 , where a solid content of the aqueous suspension is from 20 to 25%, by weight, based on the weight of the suspension.

Assignees

• Basf Se

Inventors

• Baumann Dieter
• Wloch Sebastian
• Garella Linda
• Sengpiel Robert

Classifications

• C07C227/42 Primary

  Crystallisation · CPC title

• C07B2200/13

  Crystalline forms, e.g. polymorphs · CPC title

• C07C229/06

  having only one amino and one carboxyl group bound to the carbon skeleton · CPC title

• C12P13/04

  Alpha- or beta- amino acids {(other amino acids C12P13/005)} · CPC title

• C07C229/08

  the nitrogen atom of the amino group being further bound to hydrogen atoms · CPC title