Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Silicon containing or process of making
Reexamination Certificate
1998-12-22
2001-11-06
Bell, Mark L. (Department: 1755)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Silicon containing or process of making
C502S235000, C502S238000, C502S239000, C502S242000, C502S251000, C502S256000, C502S308000, C502S309000, C502S340000, C502S341000, C502S350000, C502S355000, C502S407000, C502S415000
Reexamination Certificate
active
06313061
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention further relates to a novel method for making the agglomerate support composition and supported catalysts derived therefrom disclosed in the above-identified related patent applications.
It is well known that catalysts supported on a silica gel support are useful in the polymerization of olefins. The nature of the resulting polymer is highly dependent upon the catalyst, so that variations in the characteristics of the catalyst will cause variations in, for example, the molecular weight, melt index, bulk density, particle shape, particle size, particle size distribution and reaction temperature which may be employed to effect polymerization. Furthermore, the nature of the catalyst and its performance is highly dependent upon the properties of the material used to support the catalyst. The properties of the support are in turn dependent on its method of manufacture.
Using different support materials with different physical characteristics is known in the art. Agglomerated catalytic support materials and catalysts have been prepared by a variety of methods.
Some methods involve agglomeration of particles from various types of dispersions, e.g. colloidal sols, through various mechanisms, e.g. through gellation, recovering the agglomerate, and drying. Other methods employ spray drying to cause agglomeration.
For example, the following U.S. patents disclose various non-spray drying techniques for making silica containing supports: U.S. Pat. Nos. 3,887,494; 4,076,651; 4,657,880; 4,704,374; 4,849,390; 4,902,666; and 5,108,975.
Sano et al., U.S. Pat. No. 4,849,390 disclose supported titanium or vanadium-containing catalysts useful for polymerizing olefins which employ a silicon and/or aluminum oxide carrier. The carrier must have a specified sphericality, average pore size (180-250 angstroms), pore size distribution (60% or more of the pores have a diameter of 100 to 300 angstroms), and breakage resistance. The breakage resistance is quantified by subjecting the particles to ultrasonic waves for two hours and measuring the resulting particle size distribution. The carrier is desirably breakage resistant if ≧50% of the particles have a particle size between 50-150 microns.
The following U.S. patents disclose spray dried silica or silica containing supports which do not employ a premilling step: U.S. Pat. Nos. 3,607,777; 3,965,042; 4,070,286; 4,105,426; 4,131,542; 4,228,260; 4,272,409; 4,460,700; 4,548,912; 4,677,084; 5,128,114; 5,302,566; 5,352,645; 5,403,809, and 5,569,634.
A number of the above patents assigned to E. I. DuPont de Nemours and Company disclose attrition resistant spray dried microspheroid agglomerates derived from colloidal particles.
More specifically, Iler et al. U.S. Pat. Nos. 4,105,426 and 4,131,542 disclose macroporous microspheroids derived from a silica sol comprising a mixture of large colloidal silica particles (average particle size (APS) 0.1 to 1 micron) and small colloidal silica particles (APS 1 to 10 nanometers) which are spray dried and sintered to convert the small colloidal silica particles to mechanically strong non-porous amorphous silica cement. The large colloidal particles of the intermediate microspheroidal powder prior to sintering are held together by the small colloidal particles. The resulting microspheroids have an average pore diameter of 0.05 to 0.5 microns.
In contrast, the microspheroids made by the method of the present invention are derived primarily from non-colloidal sized particles.
Bergna et al., U.S. Pat. No. 4,131,542 spray dries a silica sol to produce porous micrograms containing constituent particles in the 5 to 80 nanometer range which are then sintered to improve attrition resistance.
Schwartz, U.S. Pat. No. 5,128,114 (see also U.S. Pat. No. 5,352,645) discloses high strength, non-agglomerated porous microspheres of silica prepared by spray drying a mixture of an aqueous silica sol and an ammonium citrate or urea additive. The additive counteracts the tendency of the silica aquasol droplets to form an impervious crust during spray drying which, in turn, prevents the droplets from rupturing. The colloidal particles in the silica aquasol range from 5 to 100 nanometers.
Spencer et al., PCT Pub. No. WO96/05236 discloses magnesium halide supported on microspheroidal agglomerates of silica subparticles having controlled hydroxyl content. The agglomerates are characterized as possessing a void fraction of from 5 to 30 percent from cross-sectional analysis of the agglomerate by a scanning electron micrograph. However, from the figures of this publication, it can be seen that very little of the void space penetrates to the surface of the agglomerate. The only spray drying method disclosed for preparing such an agglomerate is an incorporation by reference to Winyall et al., U.S. Pat. No. 3,607,777. The preparative procedures for the samples used to generate
FIGS. 1 and 2
are not disclosed, nor are the preparative procedures for the samples of Example 33. All of the agglomerated supports employed in the examples were purchased from Grace Davison under the tradename SYLOPOL®, and no preparative procedure is disclosed. Specific suitable supports mentioned are designated SYLOPOL® 948, SYLOPOL® 956, SYLOPOL® 2104, and SYLOPOL® 2212, available from Grace Davison.
Winyall et al., U.S. Pat. No. 3,607,777, discloses a preparative method which specifically avoids any milling whatsoever of the silica gel.
Sato et al. Japanese Patent Pub. 61-174103 discloses a process for producing porous spherical fine powders having an average particle size of 1 to 20 microns by spray drying a mixture of a colloidal oxide sol (10-95 parts) and inorganic oxide gel (5-90 parts). However, while the average particle size of the colloidal sol particles are less than 2,500 Angstroms, the average particle size of the gel is also in the colloidal range of less than 1 micron.
Miller et al., U.S. Pat. No. 5,569,634 discloses the preparation of porous bodies suitable for use as a catalyst support but primarily as a biocarrier, which bodies are derived from the extrusion, pelletization, balling, or granulating of ultimate particles and optional binder. The ultimate particles comprise inorganic oxide particles (which must contain at least some zeolite) of 1-1000 microns. The preferred inorganic oxide is clay (i.e., natural or synthetic hydrated aluminosilicates). The binder for the ultimate particles can be silica. The ultimate particles can be formed by spray drying a mixture of clay, zeolite, and optional binder.
The ultimate particles must possess a requisite physical integrity or they will be crushed, deformed, or attrited during the formation of the porous body. A Davison Index for attrition is disclosed which is similar to the AQI test (described hereinafter in greater detail), but much more severe, e.g., it uses an air flow rate of 21 liters per minute (AQI flow rate=9 liters/min.), for 60 minutes (AQI test=30 min.). Moreover, the Davison Index test uses a 0-20 micron base line, rather than the 0-16 micron base line of the AQI test. Suitable Davison Index values for the ultimate particle are disclosed to be 70 or less. Thus, the ultimate particle is merely an intermediate in the formation of the porous body, and the morphology of the ultimate particle is not disclosed. The use of silica gel or the milling thereof to prepare the inorganic oxides for spray drying is not disclosed.
The following patents disclose spray drying of silica supports and employ premilling of a silica gel: U.S. Pat. Nos. 5,589,150 and 5,604,170; PCT Publication Nos. WO096/34062 and WO 93/23438; and German Patent Application No. DE 41 332 30.4.
More specifically, Kano et al., U.S. Pat. No. 5,589,150 discloses a method for preparing spherular silica gel particles wherein a hydrosol is allowed to congeal to a hydrogel. This hydrogel is filtered, slurried and rinsed, and mixed with demineralized water, the filtrate adjusted to a pH of 1-10 with ammonia, and the slurry thermally treated for 1 to 50 hours at 50 to 200° C. The resulti
Carney Michael J.
Denton Dean A.
Bell Mark L.
Hailey Patricia L.
Maggio Robert A.
W. R. Grace & Co.,-Conn.
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