Process for making solid methylglycine diacetate (MGDA) alkali metal salt, and solid particles

Patent metadata

Field	Value
Publication number	US-11208375-B2
Application number	US-201816484016-A
Country	US
Kind code	B2
Filing date	Feb 20, 2018
Priority date	Feb 24, 2017
Publication date	Dec 28, 2021
Grant date	Dec 28, 2021

Abstract

Process for making solid methylglycine diacetate (MGDA) alkali metal salt (a), said process comprising the steps of (A) providing a 35 to 60% by weight aqueous solution of said MGDA salt having a temperature in the range of from 50 to 90° C., (B) adding 0.01 to 2% by weight of a particulate solid with a pore volume in the range of from 0.25 to 0.75 cm3/g, determined by nitrogen adsorption in accordance with 66134:1998-02 (b), the percentage referring to the content of (a), (C) crystallizing (a), (D) removing said crystalline (a) from the mother liquor.

First claim

The invention claimed is:

1. Solid particles of methylglycine diacetate (MGDA) alkali metal salt (a), comprising
(a1) from 1 to 10% by weight of a monoclinic alkali metal salt of MGDA, and
(a2) from 90 to 99% by weight of an orthorhombic alkali metal salt of MGDA, based on a total content of (a1) and (a2).

2. The solid particles of claim 1 , wherein (a) is selected from compounds according to general formula (I)
[CH 3 —CH(COO)—N(CH 2 —COO) 2 ]M 3-x H x   (I)

wherein
M is selected from alkali metal cations, same or different, and
x is in a range of from 0 to 1.0.

3. The solid particles of claim 1 , wherein said alkali metal salt of (a) is a trisodium salt.

4. The solid particles of claim 1 , wherein from 0.1 to 30% of the solid particles comprise a residual particulate solid (b).

5. The solid particles of claim 1 , further comprising a particulate solid (b), wherein said particulate solid (b) is selected from the group consisting of ground molecular sieves, ground alumina and silicon.

6. The solid particles of claim 1 , further comprising a particulate solid (b), wherein said particulate solid (b) is alumina.

7. A process for making a cleaning agent comprising a peroxide or a percarbonate, the process comprising adding the solid particles of claim 1 to a composition, to obtain the cleaning agent.

8. A process for making the solid methylglycine diacetate (MGDA) alkali metal salt (a) according to claim 1 , said process comprising:
(A) providing an aqueous solution comprising 35 to 60% by weight of said MGDA alkali metal salt and having a temperature in a range of from 50 to 90° C.,
(B) adding 0.01 to 2% by weight, based on a content of (a), of a particulate solid (b) with a pore volume in a range of from 0.25 to 0.75 cm 3 /g, determined by nitrogen adsorption in accordance with 66134:1998-02,
(C) crystallizing (a), to obtain a crystalline (a) and
(D) removing said crystalline (a) from the mother liquor.

9. The process of claim 8 , wherein said particulate solid (b) is selected from the group consisting of ground molecular sieves, ground alumina and ground silicon.

10. The process of claim 8 , wherein (b) has an average particle diameter in a range of from 350 to 750 μm, determined by sieving.

11. The process of claim 8 , wherein (a) is selected from compounds according to general formula (I)
[CH 3 —CH(COO)—N(CH 2 —COO) 2 ]M 3-x H x   (I)

wherein
M is selected from alkali metal cations, same or different, and
x is in a range of from 0 to 1.0.

12. The process of claim 8 , wherein (C) comprises decreasing the temperature by 20 to 80° C.

13. The process of claim 8 , wherein said particulate solid (b) is alumina.

14. The process of claim 8 , wherein said solid MGDA alkali metal salt (a) has a residual moisture content in a range of from 0.5 to 20% by weight.

15. The process of claim 8 , further comprising:
(E) adding the mother liquor from (D), in whole or in part, to an aqueous solution of MGDA alkali metal salt (a) and adjusting a concentration of the aqueous solution to 35 to 60% by weight of MGDA alkali metal salt (a).

Assignees

• Basf Se

Inventors

• Kadam Somnath Shivaji
• Jaekel Frank
• Ruether Feelly
• Karrer Lothar

Classifications

• B01D2009/0086

  Processes or apparatus therefor · CPC title

• C11D7/02

  Inorganic compounds · CPC title

• C07C227/42 Primary

  Crystallisation · CPC title

• C11D3/33 Primary

  Amino carboxylic acids · CPC title

• B01D9/0004

  cooling by heat exchange (by evaporation of components of the mixture to be separated B01D9/0013; refrigeration machines F25B) · CPC title