Silica granules for thermal treatment

Patent metadata

Field	Value
Publication number	US-12330951-B2
Application number	US-202117927040-A
Country	US
Kind code	B2
Filing date	May 14, 2021
Priority date	May 25, 2020
Publication date	Jun 17, 2025
Grant date	Jun 17, 2025

Abstract

The invention provides fumed silica granules having a BET surface area of 20 m2/g to 500 m2/g; a number average particle size d50 of 350 μm to 2000 μm; a span (d90−d10)/d50 of particle size distribution of 0.8-3.0; a bulk density of more than 0.35 g/mL; a pore volume for pores >4 nm of not more than 1.5 cm3/g, process for its preparation and use thereof as a catalyst carrier, a carrier for liquid substances, in cosmetic applications, for thermal insulation, as pharmaceutical excipient, in producing thermally treated silica granules, as an abrasive, as a component of a silicone rubber.

First claim

The invention claimed is:

1. Fumed silica granules comprising:
a BET surface area of 20 m 2 /g to 500 m 2 /g;
a number average particle size d 50 of 350 μm to 2000 μm, as determined by laser diffraction;
a span (d 90 −d 10 )/d 50 of particle size distribution of 0.8-3.0, as determined by laser diffraction;
a bulk density of more than 0.35 g/mL, as determined by mercury intrusion;
a pore volume for pores >4 nm of not more than 1.5 cm 3 /g, as determined by mercury intrusion.

2. The fumed silica granules of claim 1 , wherein the d 10 of the granules is from 100 μm to 1000 μm, as determined by laser diffraction.

3. The fumed silica granules of claim 1 , wherein the percentage of particles with a particle size of not more than 100 μm is less than 20% by weight of the granules.

4. The fumed silica granules of claim 1 , wherein the span (d 90 −d 10 )/d 50 of particle size distribution of the granules is 0.9-2.0.

5. The fumed silica granules of claim 1 , wherein the tamped density of the granules is 300 g/L-600 g/L.

6. The fumed silica granules of claim 1 , wherein the granules have a porosity of less than 77%, as determined by mercury intrusion.

7. The fumed silica granules of claim 2 , wherein the particles with a particle size of not more than 100 μm is less than 20% by weight of the granules.

8. The fumed silica granules of claim 7 , wherein the span (d 90 −d 10 )/d 50 of particle size distribution of the granules is 0.9-2.0.

9. The fumed silica granules of claim 8 , wherein the tamped density of the granules is 300 g/L-600 g/L.

10. The fumed silica granules of claim 9 , wherein the granules have a porosity of less than 77%, as determined by mercury intrusion.

11. A process for preparing the fumed silica granules of claim 1 , comprising the following steps:
a) compacting fumed silica with a water content of 0.1%-10% by weight to obtain compacted silica fragments with a tamped density of at least 200 g/L;
b) crushing the compacted silica fragments obtained is step a) and isolating crushed fragments with a size of not more than 2000 μm using a sieve with a mesh size of 1000 μm-2000 μm;
c) separating fine particles from the crushed fragments with a size of not more than 2000 μm obtained in step b) using a sieve with a mesh size of 200 μm-600 μm;
d) optionally repeating step a) with the sieved fine particles obtained in step c).

12. The process of claim 11 , wherein the process is carried out continuously.

13. The process of claim 11 , wherein, in step a), a fumed silica with a water content of 0.5%-5.0% by weight is used.

14. The process of claim 11 , wherein the mesh size of the sieve used in step b) of the process is 1000 μm-1500 μm.

15. The process of claim 11 , wherein the mesh size of the sieve used in step c) of the process is 400 μm-600 μm.

16. The process of claim 11 , further comprising step e), wherein the granules obtained in step c) are exposed at a temperature of 400° C. to 1100° C., to an atmosphere which comprises one or more reactive compounds selected from the group consisting of: chlorine; hydrochloric acid; sulphur halides; sulphur oxide halides; hydrogen; and mixtures thereof.

17. The process of claim 11 , wherein step a) is performed by means of two compacting rollers and the specific pressure applied between the two compacting rollers is more than 12 kN/cm.

18. The process of claim 13 , wherein the mesh size of the sieve used in step b) is 1000 μm-1500 μm.

19. The process of claim 18 , wherein the mesh size of the sieve used in step c) of the process is 400 μm-600 μm.

20. The process of claim 19 , further comprising step e), wherein the granules obtained in step c) of the process are exposed at a temperature of 400° C. to 1100° C., to an atmosphere which comprises one or more reactive compounds selected from the group consisting of: chlorine; hydrochloric acid; sulphur halides; sulphur oxide halides; hydrogen; and mixtures thereof.

Assignees

• Evonik Operations Gmbh

Inventors

• Giesseler Mareike
• Golchert Rainer
• Mühlig Nina
• Lygin Alexander
• Aul Wolfgang
• Renger Tobias
• Tontrup Christoph

Classifications

• C01P2006/82

  water content · CPC title

• C01P2006/14

  Pore volume · CPC title

• C01P2006/12

  Surface area · CPC title

• C01P2006/10

  Solid density · CPC title

• C01P2004/61

  Micrometer sized, i.e. from 1-100 micrometer · CPC title