Lanthanide-doped layered double hydroxides and method of producing same

Patent metadata

Field	Value
Publication number	US-11896968-B2
Application number	US-201816955740-A
Country	US
Kind code	B2
Filing date	Dec 21, 2018
Priority date	Dec 22, 2017
Publication date	Feb 13, 2024
Grant date	Feb 13, 2024

Abstract

The present disclosure relates to a method for producing lanthanide doped layered double hydroxides (Ln-doped LDHs). The method includes the steps of preparing a carbonate free alkaline solution; preparing a solution of metal salts comprising a salt of a lanthanide; co-precipitating the alkaline solution and the solution of metal salts to form a mixture and Ln-doped LDH precipitate wherein the pH of the mixture is maintained at a constant value; aging the precipitate; and separating the precipitate from the solution. The alkaline solution is an aqueous ammonia solution. The present disclosure is also related to lanthanide-doped layered double hydroxides (La-doped LDHs) obtainable by such a method, as well as to the use of the lanthanide-doped layered double hydroxides obtainable by such a method.

First claim

The invention claimed is:

1. A method for producing lanthanide doped layered double hydroxides (Ln-doped LDHs), the method comprising:
a) preparing a carbonate free alkaline solution;
b) preparing a solution of metal salts comprising a salt of a lanthanide;
c) adding the alkaline solution and the solution of metal salts to form a mixture, wherein a speed of adding the alkaline solution or of adding the solution of metal salts is set such that a pH of the mixture is maintained at a constant value so as to form Ln-doped LDH precipitate;
d) aging the precipitate; and
e) separating the precipitate from the mixture;
wherein the carbonate free alkaline solution is an aqueous ammonia solution; and
wherein the lanthanide doped layered double hydroxides have a crystal structure having a unit cell with lattice parameter a 110 at least 1.6% larger than lattice parameter a 110 of a unit cell of the crystal structure of layered double hydroxides that are not lanthanide doped.

2. The method of claim 1 , wherein the aqueous ammonia solution has a NH 3 concentration between 20% w/w and 30% w/w.

3. The method of claim 1 , wherein adding the alkaline solution and the solution of metal salts comprises adding the alkaline solution at a speed between 5 mL/min and 10 mL/min per liter of the solution of metal salts.

4. The method of claim 1 , wherein in step (c) the pH of the formed mixture is comprised between 9 and 13.

5. The method of claim 1 , wherein step (c) is performed at a temperature comprised between 1° C. and 65° C.

6. The method of claim 1 , wherein the solution of metal salts comprises a salt of a lanthanide, and salts of one or more of divalent, trivalent, and tetravalent metal cations.

7. The method of claim 6 wherein in the solution of metal salts the cationic ratios of Me2+/(Me3+ and/or Me4+)/Ln3+ are 2-4/0.8-0.95/0.05-0.2, wherein Me refers to a metal element.

8. The method of claim 6 , wherein the solution of metal salts comprises a salt of a lanthanide, aluminium and one or more of calcium, magnesium, and zinc.

9. The method of claim 8 , wherein in the solution of metal salts the molar ratio of Ca/Al/Ln is 2 to 4/0.5 to 0.95/0.05 to 0.5, or the molar ratio of Mg/Al/Ln is 2 to 4/0.5 to 0.95/0.05 to 0.5, or the molar ratio of Zn/Al/Ln is 2 to 4/0.5 to 0.95/0.05 to 0.5.

10. The method of claim 8 , wherein the solution of metal salts comprises a salt of a lanthanide, aluminium, and magnesium.

11. The method of claim 10 , wherein in the solution of metal salts the molar ratio between Mg, Al and Ln is Mg x Al y Ln z , wherein x is between 2 and 4, y is between 0.9 and 0.95, and z is between 0.05 and 0.1.

12. The method of claim 1 , wherein the solution of metal salts comprises:
CaCl 2 ·2H 2 O, AlCl 3 ·6H 2 O and LaCl 3 ·7H 2 O; or
Mg(NO 3 ) 2 ·6H 2 O, Al(NO 3 ) 3 ·9H 2 O and La(NO 3 ) 3 ·6H 2 O; or
Zn(NO 3 ) 2 ·6H 2 O, Al(NO 3 ) 3 ·9H 2 O and La(NO 3 ) 3 ·6H 2 O.

13. The method of claim 1 , wherein step (d) is performed for a period of at least 1 hour at a temperature being comprised between 1° C. and 150° C.

14. The method of claim 13 , wherein step d) comprises maintaining the precipitate and the mixture in contact with each other at a temperature between 1° C. and 65° C.

15. The method of claim 1 , further comprising:
using the lanthanide doped layered double hydroxides as sorbent for anions.

16. The method of claim 15 , wherein the lanthanide doped layered double hydroxides are used as sorbent for anions at a pH between 7 and 14.

17. The method of claim 1 , further comprising:
using the lanthanide doped layered double hydroxides as catalyst in a chemical reaction.

18. The method of claim 17 , wherein the lanthanide doped layered double hydroxides are used as catalyst at a pH between 7 and 14.

Assignees

• Vito Nv
• Univ Antwerpen

Inventors

• Seftel Elena Mihaela
• Michielsen Bart
• Mullens Steven
• Cool Pegie
• Meynen Vera

Classifications

• B01J37/031 Primary

  Precipitation · CPC title

• B01J20/043

  Carbonates or bicarbonates, e.g. limestone, dolomite, aragonite · CPC title

• B01J20/3085

  Chemical treatments not covered by groups B01J20/3007 - B01J20/3078 · CPC title

• B01J27/236

  Hydroxy carbonates · CPC title

• B01J37/033

  Using Hydrolysis · CPC title