Spheroidal alumina particles and catalysts employing the particles as a support

• US 4,390,456 A
• Filed: 07/17/1981
• Issued: 06/28/1983
• Est. Priority Date: 08/08/1979
• Status: Expired due to Term

• Current Assignee: W R Grace & Company - CONN (Standard Industries Holdings, Inc.)
• Original Assignee: WR Grace & Company
• Inventors: Sanchez, Moises G., Laine, Norman R., Ernest, Michael V.
• Primary Examiner(s): Shine, W. J.
• Application Number:
  US06/284,317
• Time in Patent Office: 711 Days
• Field of Search: 252/448, 252/463, 252/466 PT, 423/213.5, 423/628
• US Class Current: 502/8
• CPC Class Codes: B01J 21/04 Alumina
• CPC Class Codes: B01J 23/44 Palladium
• CPC Class Codes: B01J 35/397 Egg shell like
• CPC Class Codes: B01J 35/60 characterised by their surface properties or porosity
• CPC Class Codes: B01J 35/615 100-500 m2/g
• CPC Class Codes: B01J 35/635 0.5-1.0 ml/g
• CPC Class Codes: B01J 35/647 2-50 nm
• CPC Class Codes: B01J 35/651 50-500 nm
• CPC Class Codes: B01J 35/653 500-1000 nm
• CPC Class Codes: C01F 7/021 After-treatment of oxides or hydroxides
• CPC Class Codes: C01F 7/34 Preparation of aluminium hydroxide by precipitation from solutions containing aluminium salts
• CPC Class Codes: C01P 2004/32 Spheres
• CPC Class Codes: C01P 2004/61 Micrometer sized, i.e. from 1-100 micrometer
• CPC Class Codes: C01P 2006/10 Solid density
• CPC Class Codes: C01P 2006/11 Powder tap density
• CPC Class Codes: C01P 2006/12 Surface area
• CPC Class Codes: C01P 2006/14 Pore volume
• CPC Class Codes: C01P 2006/16 Pore diameter
• CPC Class Codes: C01P 2006/17 Pore diameter distribution
• CPC Class Codes: C01P 2006/21 Attrition-index or crushing strength of granulates
• CPC Class Codes: C01P 2006/22 : Rheological behaviour as dispersion, e.g. viscosity, sedimentation stability

Abstract

Spheroidal alumina particles have a combination of high macroporosity, surface area, crush strength and low attrition loss and bulk density. The particles are prepared by an improved external gelation oil-drop process. In the process a slurry of alumina, preferably a microcrystalline boehmite-pseudoboehmite intermediate, is prepared in an acidic aqueous medium and droplets of the slurry are passed through air into a column containing an upper body of water-immiscible liquid and ammonia and a lower body of aqueous coagulating agent. Catalysts employing the particles as a support and having catalytic agents distributed at controlled depths in the particle have excellent initial and sustained activity and durability, especially for eliminating pollutants in automotive exhaust streams.

Claims

1. A catalyst support comprising spheroidal alumina particles having a total pore volume of about 0.8 to about 1.7 cubic centimeters per gram, a pore volume of about 0.5 to about 1.0 cubic centimeters per gram in pores of 100 to 1000 A. in diameter, a pore volume of about 0.1 to about 0.4 cubic centimeters per gram in pores of 1000 to 10,000 A. in diameter, an attrition loss of less than about 5%, and a compacted bulk density of about 20 to about 36 pounds per cubic foot.

2. The support of claim 1 having a pore volume of 0 to about 0.06 cubic centimeters per gram in pores of less than 100 A. in diameter.

3. The support of claim 1 having a volume shrinkage of less than about 6% upon exposure to a temperature of 1800°

F. for 24 hours and a crush strength of at least about 5 pounds.

4. The support of claim 1 having a pore volume of about 0.2 to about 0.3 cubic centimeters per gram in pores of from 1000 to 10,000 A. in diameter, a pore volume of about 0.6 to about 0.9 centimeters per gram in pores of from 100 to 1000 A. in diameter, a pore volume of 0 to about 0.04 cubic centimeters per gram in pores ofless than 100 A. in diameter, and a total pore volume of about 0.9 to about 1.2 cubic centimeters per gram.

5. The support of claim 4 having an attrition loss of less than about 2%, a volume shrinkage of less than about 4% upon exposure to a temperature of 1800°

F. for 24 hours, a compacted bulk density of about 26 to about 32 pounds per cubic foot, and a crush strength of greater than about 7 pounds.

6. A catalyst comprising the support of claim 1 having deposited thereon a catalytically effective amount of at least one catalytically active metal or metal oxide.

7. The catalyst of claim 6 in which the catalytically active metal is a platinum group metal selected from the group consisting of platinum, palladium, ruthenium, iridium, rhodium, osmium and mixtures thereof.

8. The catalyst of claim 7 in which the platinum group metal is in an amount up to about 1.0% by weight of the catalyst.

9. The catalyst of claim 7 in which the platinum group metal comprises platinum and palladium.

10. The catalyst of claim 9 in which the platinum and the palladium are deposited on separate spheroidal alumina particles.

11. The catalyst of claim 9 in which the metals are deposited such that about 50% of the total metal surface area is located at depths greater than about 50 microns from the external boundary of the support.

12. The catalyst of claim 9 in which the metals are deposited such that about 50 weight percent on the total metals is located at depths greater than about 75 microns from the external boundary of the support.

13. The catalyst of claim 7 in which the catalytically active metal comprises platinum, palladium, and rhodium.

14. The catalyst of claim 13 in which the metals are deposited such that about 50% of the total metal surface area is located at depths greater than about 50 microns from the external boundary of the support.

15. The catalyst of claim 13 in which the metals are deposited such that about 50 weight percent of the total metals is located at depths greater than about 75 microns from the external boundary of the support.

16. A catalyst comprising the support of claim 5 having deposited thereon catalytically effective amounts of platinum and palladium such that about 50% of the total metal surface area is located at depths greater than about 50 microns from the external surface of the support.

17. The catalyst of claim 7 in which the maximum depth of metal penetration is about 150-400 microns.

18. The catalyst of claim 7 in which the maximum depth of metal penetration is about 150-250 microns.

19. The catalyst of claim 13 in which the maximum depth of penetration of the platinum is about 125-400 microns, the maximum depth of penetration of the palladium is about 125-400 microns, and the maximum depth of penetration of the rhodium is about 125-250 microns.

20. The catalyst of claim 19 in which the maximum depth of penetration of the platinum is about 125-250 microns, the maximum depth of penetration of the palladium is about 125-250 microns, and the maximum depth of penetration of the rhodium is about 125-200 microns.