Mixed oxide with high pore volume

Patent metadata

Field	Value
Publication number	US-12337300-B2
Application number	US-202017432176-A
Country	US
Kind code	B2
Filing date	Feb 28, 2020
Priority date	Mar 3, 2019
Publication date	Jun 24, 2025
Grant date	Jun 24, 2025

Abstract

The present invention relates to a mixed oxide composition based on zirconium and cerium, to the process for preparing it and to its use in the field of catalysis. The mixed oxide is characterized by a high specific surface area and a specific porosity after calcination at 1100° C.

First claim

The invention claimed is:

1. A mixed oxide comprising zirconium, cerium, lanthanum and optionally at least one rare-earth element other than cerium and other than lanthanum (RE) with the following composition:
between 18.0% and 70.0% by weight of cerium;
between 1.0% and 10.0% by weight of lanthanum;
up to 10.0% by weight of the at least one rare earth element(s) (RE(s)) other than cerium and other than lanthanum;
the remainder as zirconium;
the mixed oxide being in the form of particles exhibiting a d50 strictly higher than 2.5 μm and the proportions of the elements (Ce, La, RE, Zr) being given by weight of oxide relative to the mixed oxide as a whole, characterized in that:
it exhibits a specific surface area (BET) of at least 28 m 2 /g after calcination in air at 1100° C. for 4 hours;
the peak with the highest intensity in the domain of the pores with a pore size lower than 500 nm, is between 70 nm, this value being excluded, and 500 nm, and corresponds to a pore size D p,1100° C./4 h ; and
the peak with the highest intensity in the domain of the pores with a pore size lower than 500 nm is between 35 nm and 75 nm, and corresponds to a pore size D p,900° C./4 h , and
it exhibits a total pore volume V 500 nm,1100° C./4 h for the pores with a size lower than 500 nm, of at least 0.30 ml/g; wherein
the pore size D p,1100° C./4 h and the total pore volume V 500 nm,1100° C./4 h being determined by mercury porosimetry on the mixed oxide after calcination in air at 1100° C. for 4 hours and D p,900° C./4 h , is determined by mercury porosimetry on a mixed oxide after calcination in air at 900° C. for 4 hours.

2. The mixed oxide according to claim 1 , further comprising hafnium and wherein the proportion of hafnium is lower or equal to 2.5%, this proportion being given by weight of oxide relative to the mixed oxide as a whole.

3. The mixed oxide according to claim 1 , consisting of a combination of the oxides of zirconium, of cerium, of lanthanum, optionally of at least one rare earth element other than cerium and other than lanthanum and optionally of hafnium, with the following composition:
between 18.0% and 70.0% by weight of cerium;
between 1.0% and 10.0% by weight of lanthanum;
up to 10.0% by weight of the rare earth element(s) (RE(s)) other than cerium and other than lanthanum;
a proportion of hafnium lower or equal to 2.0%;
the remainder as zirconium;
the mixed oxide being in the form of particles exhibiting a d50 strictly higher than
2.5 μm and the proportions of the elements (Ce, La, RE, Hf, Zr) being given by weight of oxide relative to the mixed oxide as a whole, characterized in that:
it exhibits a specific surface area (BET) of at least 28 m 2 /g after calcination in air at 1100° C. for 4 hours;
the peak with the highest intensity in the domain of the pores with a size lower than 500 nm corresponds to a pore size D p,1100° C./4 h between 70 nm, this value being excluded, and 500 nm; and
the peak with the highest intensity in the domain of the pores with a pore size lower than 500 nm is between 35 nm and 75 nm, and corresponds to a pore size D p,900° C./4 h , and
it exhibits a total pore volume V 500 nm,1100° C./4 h for the pores with a size lower than 500 nm, of at least 0.30 ml/g;
wherein
the pore size D p, 1100° C./4 h and the total pore volume V 500 nm,1100° C./4 h being determined by mercury porosimetry on the mixed oxide after calcination in air at 1100° C. for 4 hours and D p,900° C./4 h , is determined by mercury porosimetry on a mixed oxide after calcination in air at 900° C. for 4 hours.

4. The mixed oxide according to claim 1 , wherein the proportion of cerium is:
between 25.0% and 65.0% (this value being excluded).

5. The mixed oxide according to claim 1 , wherein the proportion of cerium is:
between 35.0% and 55.0%.

6. The mixed oxide according to claim 1 , wherein the proportion of lanthanum is between 3.0% and 10.0%.

7. The mixed oxide according to claim 1 , wherein the mixed oxide is a mixed oxide of zirconium, of cerium, of lanthanum and of at least one rare-earth element (RE) other than cerium and other than lanthanum and the total proportion of the rare-earth element(s) other than cerium and other than lanthanum is up to 10.0%.

8. The mixed oxide according to claim 1 , wherein the proportion of zirconium is at least 20.0%.

9. The mixed oxide according to claim 1 , wherein the proportion of zirconium is at most 79.0%.

10. The mixed oxide according to claim 1 , wherein the mixed oxide exhibits a specific surface area (BET) of at least 50 m 2 /g after calcination in air at 1000° C. for 4 hours.

11. The mixed oxide according to claim 1 , wherein the mixed oxide exhibits a specific surface area (BET) of at least 60 m 2 /g after calcination in air at 900° C. for 4 hours.

12. The mixed oxide according to claim 1 , wherein after calcination in air at 1100° C. for 4 hours, it exhibits a total pore volume V 500 nm,1100° C./4 h for the pores with a size lower than 500 nm, between 0.30 and 0.70 ml/g.

13. The mixed oxide according to claim 1 , wherein after calcination in air at 1100° C. for 4 hours, the mixed oxide exhibits a total pore volume of at least 0.60 ml/g.

14. The mixed oxide according to claim 1 , characterized by a specific surface area (BET) after calcination in air at 1100° C. for 4 hours between 28 and 40 m 2 /g.

15. The mixed oxide according to claim 1 , characterized by a specific surface area (BET) after calcination in air at 1000° C. for 4 hours between 50 and 70 m 2 /g.

16. The mixed oxide according to claim 1 , characterized by a specific surface area (BET) after calcination in air at 900° C. for 4 hours between 60 and 90 m 2 /g.

17. The mixed oxide according to claim 1 , characterized by:
a specific surface area (BET) of at least 30 m 2 /g after calcination in air at 1100° C. for 4 hours;
a peak with the highest intensity in the domain of the pores with a size lower than 500 nm which corresponds to a pore size D p,1100° C./4 h between 100 and 400 nm;
a total pore volume V 500 nm,1100° C./4 h for the pores with a size lower than 500 nm, of at least 0.50 ml/g;
a total pore volume of at least 1.00 ml/g after calcination in air at 1100° C. for 4 hours.

18. The mixed oxide according to claim 1 , characterized by a ratio α lower than 0.35, α being defined by the following formula:
α= V 70 nm,1100° C./4 h /V 500 nm,1100° C./4 h

wherein V 70 nm, 1100° C./4 h is the total pore volume for the pores with a size lower than 70 nm, after calcination in air at 1100° C. for 4 hours.

19. A process of preparation of a mixed oxide according to claim 1 , the process comprising the following steps:
(a) heating an aqueous acidic dispersion S is heated at a temperature between 100° C. and 180° C. in order to obtain a dispersion comprising a liquid medium and a precipitate, wherein the dispersion S comprises:
(i) cerium nitrate with a Ce IV /Ce IV +Ce III molar ratio of at least 90.0 mol %;
(ii) lanthanum nitrate;
(iii) optionally at least one nitrate of a rare earth element (RE) other than cerium and other than lanthanum; and
(iv) particles of zirconium oxyhydroxide wherein the powder of zirconium oxyhydroxide used for the preparation of the dispersion exhibits an average size d50 between 5.0 μm and 100.0 μm, d50 corresponding to the median value of a distribution of size of the particles (in volume) obtained with a laser diffraction particle size analyzer;
the dispersion S being characterized by a molar ratio H+/Zr between 1.0 and 3.5;
(b) adding an a

Assignees

• Rhodia Operations

Inventors

• Ohtake Naotaka
• Sasaki Toshihiro

Classifications

• B01J35/651

  50-500 nm · CPC title

• B01J35/635

  0.5-1.0 ml/g · CPC title

• B01J35/633

  less than 0.5 ml/g · CPC title

• B01J35/615

  100-500 m2/g · CPC title

• B01J35/613

  10-100 m2/g · CPC title