Claims
- 1. A particle selected from the group consisting of adsorbents and catalysts wherein said particle comprises an adsorbent or a catalyst and an outer layer comprising a metal oxide layer wherein said particle is selected from the group consisting of porous refractory oxides and molecular sieves wherein said refractory oxides are selected from the group consisting of aluminas, silica, silica-alumina, zirconia, silica-zirconia, titania, magnesia and combinations thereof, wherein said metal oxide layer is derived from a colloidal solution selected from the group consisting of silica, alumina, and zirconia and combinations thereof wherein at least 60 percent of the said metal oxide is present in a band extending from the surface towards the center and having a width of less than 50 microns.
- 2. The particle of claim 1 wherein said silica in said colloidal solution comprises silica particles having an average diameter of about 4 to 10 nm.
- 3. The particle of claim 1 wherein about 0.5 to 3 percent of said particle comprises said metal oxide.
- 4. The particle of claim 1 wherein about 1 to 2 percent of said particle comprises said metal oxide.
- 5. The particle of claim 1 wherein about 1.5 to 2.0 percent of said particle comprises said metal oxide.
- 6. The particle of claim 1 wherein said aluminas are selected from the group consisting of alumina and aluminum silicates.
- 7. The particle of claim 1 wherein said catalysts and adsorbents are activated prior to application of said colloidal metal oxide solution.
- 8. The particle of claim 1 wherein the band of metal oxide extending from the surface towards the center has a width of less than about 20 microns.
- 9. The particle of claim 1 wherein the particle has an attrition loss of less than 0.5 wt-%.
- 10. The particle of claim 1 wherein said metal oxide is silica.
- 11. A method for producing a catalyst or an adsorbent comprising:
a) forming and activating a catalyst or an adsorbent particle; and then b) coating said catalyst or adsorbent particle with a coating solution comprising colloidal metal oxide to provide a narrow layer of colloidal metal oxide dispersed thereon.
- 12. The method of claim 11 wherein the coating solution further comprises an ion selected from the group consisting of sodium, chloride and hydrogen.
- 13. The method of claim 11 wherein said coating solution is applied by a spraying means.
- 14. The method of claim 11 wherein said catalyst or adsorbent is selected from the group consisting of porous refractory oxides and molecular sieves.
- 15. The method of claim 14 wherein said refractory oxides are selected from the group consisting of aluminas, silica, silica-alumina, zirconia, silica-zirconia, titania, magnesia and combinations thereof.
- 16. The method of claim 11 wherein said metal oxide is selected from the group consisting of silica, alumina, zirconia and combinations thereof.
- 17. The method of claim 11 wherein said metal oxide is silica.
- 18. The method of claim 11 wherein said colloidal metal oxide comprises silica particles having an average diameter of about 4 to 10 nm.
- 19. The method of claim 14 wherein said molecular sieve is a zeolite.
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation-in-part of copending application Ser. No. 09/796,218 filed Feb. 28, 2001.
Continuation in Parts (1)
|
Number |
Date |
Country |
Parent |
09796218 |
Feb 2001 |
US |
Child |
10228115 |
Aug 2002 |
US |