Lanthanide-doped layered double hydroxides and method of producing same

Patent metadata

Field	Value
Publication number	US-2020325031-A1
Application number	US-201816955740-A
Country	US
Kind code	A1
Filing date	Dec 21, 2018
Priority date	Dec 22, 2017
Publication date	Oct 15, 2020
Grant date	—

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

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 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.

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 in step (c) adding the alkaline solution and the solution of metal salts is performed by adding the alkaline solution to the solution of metal salts, a speed of adding being 5 to 10 mL/min per liter 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 . Lanthanide doped layered double hydroxides (Ln-doped LDHs), wherein a lattice parameter a 110 of a unit cell of a crystal structure of the lanthanide doped layered double hydroxides is at least 1.6% larger than a lattice parameter a 110 of a unit cell of a crystal structure of a non-doped layered double hydroxide material.

16 . The lanthanide doped layered double hydroxides according to claim 15 , comprising brucite-like layers and interlayers between the brucite-like layers, wherein at least 90% of anions in the interlayers are nitrate anions.

17 . The lanthanide doped layered double hydroxides according to claim 16 , wherein the lanthanide is doped into the brucite-like layer of the layered double hydroxides, such that the layered double hydroxides comprise a non-segregated lanthanide phase.

18 . (canceled)

19 . The lanthanide doped layered double hydroxides according to claim 15 , wherein the lanthanide is La, Eu, or Tb.

20 - 22 . (canceled)

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

24 . The method of claim 23 , wherein the lanthanide doped layered double hydroxides are used as sorbent for anions at a pH between 7 and 14.

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

26 . The method of claim 25 , 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

• C01F7/784

  Layered double hydroxide, e.g. comprising nitrate, sulfate or carbonate ions as intercalating anions · CPC title

• C01F7/785

  Hydrotalcite · CPC title

• B01J20/06

  comprising oxides or hydroxides of metals not provided for in group B01J20/04 · CPC title

• C02F1/281

  using inorganic sorbents · CPC title