Claims
- 1. An attrition resistant catalytic composite consisting essentially of metal crystallites dispersed throughout high-strength, non-agglomerated porous silica microspheres having an average diameter in the range of 1.0 to 50 microns and an average pore size of 2 to 20 nm, which are produced by the process of
- (a) mixing an aqueous sol of colloidal silica particles, having a diameter in the range of 5 to 100 nm, with an effective amount of a soluble additive selected from the group consisting of ammonium citrate and urea to inhibit premature formation of an impervious crust;
- (b) spray drying the mixture to form a powder consisting of microspherical silica particles, said particles comprising a conglomerate of the original colloidal silica particles and said additive;
- (c) calcining the spray dried powder to remove volatile components and to sinter the colloidal silica particles within the microspheres without fusing the microspheres into agglomerates;
- (d) preparing an aqueous solution of a metal salt or metal salts;
- (e) slurrying said powder with said solution; and
- (f) drying, treating in a hydrogen atmosphere the resulting powder.
- 2. An attrition resistant catalytic composite consisting essentially of metal crystallites dispersed throughout high-strength, non-agglomerated porous silica microspheres having an average diameter in the range of 1.0 to 50 microns and an average pore size of 2 to 20 nm, which are produced by the process of:
- (a) preparing an aqueous solution of a metal salt or metal salts;
- (b) dissolving an additive selected from ammonium citrate or urea;
- (c) adding an aqueous sol of colloidal silica particles, having a diameter in the range of 5 to 100 nanometers;
- (d) spray drying the mixture to form a powder consisting of microspherical silica particles, said particles comprising a conglomerate of the original silica particles with metal salts and ammonium citrate or urea distributed throughout; and
- (e) calcining to remove volatile components and to sinter the colloidal silica particles within the microspheres without fusing the microspheres into agglomerates.
- 3. The process of claim 2, which further comprises the step of:
- (f) treating in a hydrogen atmosphere.
- 4. A process for preparing an attrition resistance catalyst wherein said catalyst is made by spray drying a mixture comprising colloidal silica, an additive selected from ammonium citrate or urea, and platinum salt, palladium salt or mixtures thereof.
- 5. The silica microspheres of claim 1 in which at least 68% of the microspheres are within the size range of 0.3 d to 2.5 d, where d is the weight average particle size in microns, and at least 80% of the pores within any silica microsphere are between the size range of 0.2 p to 2.0 p, where p is the average pore size in nanometers.
- 6. The silica microspheres of claim 1 in which at least 80% of the pores within any silica microsphere are between the size range of 0.5 to 1.5 p, where p is the average pore size in nanometers.
- 7. The catalytic composite of claim 1 or claim 2 or claim 3 wherein the metal crystallite is selected from Group VIII metals.
- 8. The catalytic composite of claim 1 wherein the metal crystallites comprise platinum, palladium and mixtures thereof.
CROSS REFERENCE TO EARLIER FILED APPLICATION
This is a continuation-in-part of application Ser. No. 07/907,962 filed Jul. 2, 1992, abandoned in view of filing this continuation-in-part application under 37 CFR 1.62, which is a division of application Ser. No. 07/587,879 filed Sep. 25, 1990, now U.S. Pat. No. 5,128,114 issued Jul. 7, 1992, which is a continuation-in-part of application Ser. No. 07/344,975 filed Apr. 14, 1989, abandoned.
US Referenced Citations (14)
Foreign Referenced Citations (4)
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Date |
Country |
0117306 |
Sep 1984 |
EPX |
298062 |
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EPX |
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Nov 1990 |
EPX |
2149340 |
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JPX |
Non-Patent Literature Citations (1)
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Chemical Abstracts, "Adsorbents, Catalysts, Supports and Their Manufacture", Jeemusu (1989) Japan JP01307444 (Dec. 12, 1989). |
Divisions (1)
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Date |
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Parent |
587879 |
Sep 1990 |
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Continuation in Parts (2)
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Number |
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907962 |
Jul 1992 |
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Parent |
344975 |
Apr 1989 |
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