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  • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
  • C01B33/18—Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof
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  • B01J2/00—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic
  • B01J2/02—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic by dividing the liquid material into drops, e.g. by spraying, and solidifying the drops
  • B01J2/04—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic by dividing the liquid material into drops, e.g. by spraying, and solidifying the drops in a gaseous medium
• • B—PERFORMING OPERATIONS; TRANSPORTING
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  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J2/00—Processes or devices for granulating materials, e.g. fertilisers in general; Rendering particulate materials free flowing in general, e.g. making them hydrophobic
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  • C01F17/00—Compounds of rare earth metals
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  • C01F17/206—Compounds containing only rare earth metals as the metal element oxide or hydroxide being the only anion
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  • C01F7/00—Compounds of aluminium
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  • C01F7/021—After-treatment of oxides or hydroxides
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  • C01F7/00—Compounds of aluminium
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  • C01F7/025—Granulation or agglomeration
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  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
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  • C01F7/00—Compounds of aluminium
  • C01F7/02—Aluminium oxide; Aluminium hydroxide; Aluminates
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  • C01P2004/80—Particles consisting of a mixture of two or more inorganic phases
  • C01P2004/82—Particles consisting of a mixture of two or more inorganic phases two phases having the same anion, e.g. both oxidic phases
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  • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
  • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
  • C04B35/62605—Treating the starting powders individually or as mixtures
  • C04B35/62695—Granulation or pelletising

Definitions

• Embodiments of the present disclosure generally relate to methods for processing fumed metallic oxides. More specifically, embodiments of the present disclosure relate to methods for processing fumed metallic oxides that exhibit a dominantly branched morphology into metallic oxide agglomerations that exhibit a dominantly globular morphology.
• fumed metallic oxides such as “fumed silica” (fumed silicon dioxide, Si0 2 ) and “fumed alumina” (fumed aluminum oxide, A1 2 0 3 ), can be used in a wide variety of applications, including use as adhesives, pharmaceutical and food additives, beauty and skin care products, ink toners, and coatings.
• Fumed metallic oxides are, in some embodiments, fine white powders with high surface area that become colorless when dispersed in a liquid or polymer.
• fumed metallic oxides may, in some embodiments, exhibit a very high fractal dimension and a dominantly branched morphology, which can create difficulties in handling, dispensing, storing, and conveying the fumed oxide. Additionally, fumed metallic oxides may pose serious inhalation risks due to their propensity to become airborne and potentially break apart into nanoscale primary particles.
• a method for processing fumed silica into silica agglomerations may include providing fumed silica particles, combining the particles with a liquid carrier to form a solution of suspended fumed silica particles, atomizing the solution, and subjecting the atomized droplets to a temperature range to remove the liquid carrier and produce the silica agglomerations.
• the provided fumed silica may have a Brunauer Emmett Teller (BET) surface area of greater than about 50 meters squared per gram (m /g), a dominant branched morphology comprising from 5 nanometer (nm) to 50 nm primary particles, and an average bulk density of less than 64 kilograms per cubic meter (kg/m ).
• BET Brunauer Emmett Teller
• the solution of suspended fumed silica particles may comprise from about 2 weight percent (wt%) to about 8 wt% of the fumed silica particles.
• at least a majority of the silica-containing droplets may have a droplet diameter of about 250 nm to about 100 micrometers ( ⁇ ) and a fumed silica particle weight percentage of from about 2 wt% to about 8 wt%.
• the droplets may be subjected to a temperature of from about 50° C to about 1500° C for a period of time of at least about 0.5 seconds to produce silica agglomerations.
• Substantially all of the produced silica agglomerations may exhibit a second BET surface area that is at least about 75% of the BET surface area of the fumed silica particles and may have a dominant globular morphology characterized by an average bulk density of greater than 64 kg/m .
• a method for processing fumed metallic oxides into metallic oxide agglomerations may include providing fumed metallic oxide particles, combining the particles with a liquid carrier to form a solution of suspended fumed metallic oxide particles, atomizing the solution, and subjecting the atomized droplets to a temperature range to remove the liquid carrier and produce the metallic oxide agglomerations.
• the provided fumed metallic oxide particles may have a BET surface area of greater than about 50 m /g and a dominant branched morphology comprising from 5 nm to 50 nm primary particles.
• the solution of suspended fumed metallic oxide particles may comprise from about 2 wt% to about 8 wt% of the fumed metallic oxide particles.
• the metallic oxide-containing droplets may have a droplet diameter of about 250 nm to about 100 micrometers ( ⁇ ) and a fumed metallic oxide particle weight percentage of from about 2 wt% to about 8 wt%.
• the droplets may be subjected to a temperature of from about 50° C to about 1500° C for a period of time of at least about 0.5 seconds to produce metallic oxide agglomerations.
• Substantially all of the produced metallic oxide agglomerations may exhibit a second BET surface area that is at least about 75% of the BET surface area of the fumed metallic oxide particles, and may have a dominant globular morphology.
• FIG. 1 is a schematic view of a method for processing fumed metal oxides, according to embodiments shown and described herein;
• FIG. 2 is a magnified schematic view of a metallic oxide-containing droplet, according to embodiments shown and described herein;
• FIG. 3 is a magnified schematic view of a method for processing fumed metal oxides, according to embodiments shown and described herein;
• FIG. 4A is a magnified schematic view of a metallic oxide-containing droplet, according to embodiments shown and described herein;
• FIG. 4B is a magnified schematic view of a metallic oxide-containing droplet
• FIG. 4C is a magnified schematic view of a metallic oxide-containing droplet
• FIG. 5A is a magnified schematic view of a silica-containing droplet
• FIG. 5B is a magnified schematic view of a silica-containing droplet
• FIG. 5C is a magnified schematic view of a silica-containing droplet in accordance with embodiments shown and described herein;
• FIG. 6A is an image of fumed silica particles, as viewed by a scanning electron microscope
• FIG. 6B is an image of fumed silica particles, as viewed by a scanning electron microscope
• FIG. 6C is an image of silica agglomerations, as viewed by a scanning electron microscope, according to embodiments shown and described herein;
• FIG. 6D is another image of silica agglomerations, as viewed by a scanning electron microscope, according to embodiments shown and described herein;
• FIG. 6E is an image of a silica agglomeration, as viewed by a scanning electron microscope, according to embodiments shown and described herein;
• FIG. 6F is another image of a silica agglomeration, as viewed by a scanning electron microscope, according to embodiments shown and described herein.
• FIG. 1 is a schematic view of a method for processing fumed metal oxides, according to embodiments of the present disclosure.
• fumed refers to one or more particles generated in a high-temperature, vapor-phase process involving hydrolysis of a volatile composition, comprising at least one metal or metalloid, such as in a flame of hydrogen and oxygen.
• fumed silica may be generated by a pyrogenic process such as vapor phase hydrolysis or pyrolysis of silicon tetrachloride at a temperature of about 1800° C to produce fumed silica particles, which may comprise numerous nanometer-sized primary particles that may be aggregated and agglomerated to form larger clusters with chain-like structures.
• fumed metallic oxide particles 110 may include, but are not limited to, CAB-O-SIL TS-610 and ULTRABON 4740 fumed silica (available from Cabot Corporation, Boston, Mass., USA) and AEROSIL fumed silica and AEROXIDE Alu fumed alumina (available from Evonik Corporation, Essen Germany).
• FIG. 1 depicts a schematic view of a method comprising providing fumed metallic oxide particles 110, which may undergo a combining step 105 to mix the fumed metallic oxide particles 110 with a liquid carrier 130 to form a solution of suspended fumed metallic oxide particles 120.
• the fumed metallic oxide particles 110 may comprise silicon dioxide (Si0 2 , "silica”), aluminum oxide (A1 2 0 3 , “alumina”), titanium oxide (Ti0 2 ), cerium oxide (Ce0 2 ), boron trioxide (B 2 0 3 ), zirconium dioxide (Zr0 2 ), germanium dioxide (Ge0 2 ), tungsten trioxide (W0 3 ), niobium pentaoxide (Nb 2 Os), or combinations thereof.
• silicon dioxide Si0 2 , "silica”
• aluminum oxide A1 2 0 3 , "alumina”
• titanium oxide Ti0 2
• Ce0 2 cerium oxide
• B 2 0 3 boron trioxide
• Zr0 2 zirconium dioxide
• germanium dioxide Ge0 2
• W0 3 tungsten trioxide
• Nb 2 Os niobium pentaoxide
• other metallic or bi-metallic oxides may be used.
• the fumed metallic oxide particles 110 may have a Brunauer Emmett Teller (BET) surface area of greater than about 50 meters squared per gram (m /g).
• BET surface area refers to the average surface area of the metallic oxide particles as measured by the BET (Brunauer Emmett Teller) nitrogen absorption method according to ASTM D-6556.
• the fumed metallic oxide particles 110 may have a
• the fumed metallic oxide particles 110 may have a BET surface area of from about 50 m 2 /g to about 650 m 2 /g, or from about 200 m 2 /g to about 600 m 2 /g, or from about 250 m 2 /g to about 650 m 2 /g, or from about 350 m 2 /g to about 650 m 2 /g.
• the fumed metallic oxide particles 110 may have a BET surface area of from about 50 m 2 /g to about 600 m 2 /g, or from about 50 m 2 /g to about 500 m 2 /g, or from about 50 m 2 /g to about 400 m 2 /g.
• the fumed metallic oxide particles 110 may, in some embodiments, have a BET surface area of from about 150 m 2 /g to about 450 m 2 /g, or from about 250 m 2 /g to about 450 m 2 /g, or from about 200 m 2 /g to about 500 m 2 /g, or from about 350 m 2 /g to about 600 m 2 /g, or from about 300 m 2 /g to about 500 m 2 /g. Having a high BET surface area may be commercially desired. Further, fumed metallic oxide particles 110 having a high BET surface area may allow the produced metallic oxide agglomerations 410 to retain the high surface area of the fumed metallic oxide particles 110.
• the fumed metallic oxide particles 110 may be characterized by a dominant branched morphology comprising from about 5 nanometer (nm) to about 50 nm primary particles.
• dominant branched morphology refers to a particle in which branched, subdivided portions of the particle make up a majority of the dimensional surface extremities of the particle.
• the fumed metallic oxide particles 110 may have primary particles from about 10 nm to about 50 nm, or from about 15 nm to about 50 nm, or from about 25 nm to about 50 nm, or from about 35 nm to about 50 nm, or from about 10 nm to about 40 nm, or from about 10 nm to about 30 nm, or from about 10 nm to about 20 nm, or from about 25 nm to about 45 nm.
• the size of the primary particles may be important to allow the fumed metallic oxide particles 110 to be sufficiently branched so as to exhibit a high BET surface area.
• the average primary particle size should be high enough to allow for increased BET surface area (such as above about 5 nm) but should not be too high (such as above about 50 nm) to where the fumed metallic oxide particles 110 exhibit more of a straight chain morphology rather than branched.
• the provided fumed metallic oxide particles 110 may undergo a combining step 105 in which they are combined with a liquid carrier 130 to form a solution of suspended fumed metallic oxide particles 120.
• solution of suspended fumed metallic oxide particles refers to a suspension of fumed metallic oxide particles in which fumed metallic oxide particles 110 are dispersed throughout the solution.
• the solution of suspended fumed metallic oxide particles 120 may be a colloidal suspension, meaning that the fumed metallic oxide particles 110 may not substantially settle to the bottom of the solution, but may remain a suspension in which the fumed metallic oxide particles 110 are dispersed throughout the solution.
• the fumed metallic oxide particles 110 may settle to the bottom of the liquid carrier 130 and may require energy (such as stirring or sonication) to resuspend the fumed metallic oxide particles 110 in the liquid carrier 130 to regenerate the solution of suspended fumed metallic oxide particles 120.
• the liquid carrier 130 may be any liquid suitable to combine with the fumed metallic oxide particles 110 to support a suspension.
• the liquid carrier 130 may be an organic or inorganic solvent.
• the liquid carrier 130 may comprise H 2 0, and, in some embodiments, the liquid carrier 130 may be water.
• the liquid carrier 130 may comprise supercritical carbon dioxide (“scC0 2 ") or an alcohol.
• scC0 2 supercritical carbon dioxide
• the solvent may, in some embodiments, comprise a supercritical fluid, which does not have a distinct liquid or gas phase.
• ultrapure water including but not limited to distilled or deionized water, may be used as the liquid carrier 130 to produce resulting metallic oxide agglomerations 410 with a substantially unchanged chemical composition. The ultrapure water may not react with the fumed metallic oxide particles 110 and may evaporate without leaving a residue on the produced metallic oxide agglomerations 410.
• the liquid carrier 130 may be selected such that the produced metallic oxide agglomerations 410 exhibit a high purity, such that they have substantially the same chemical composition as the provided fumed metallic oxide particles 110.
• the produced metallic oxide agglomerations 410 may be comprised of less than about 2 wt% of impurities.
• the metallic oxide agglomerations 410 may be comprised of less than 5 wt% impurities, or less than 3 wt% impurities, or less than 1 wt% impurities, or less than 0.5 wt% impurities.
• the method may comprise doping the solution of suspended fumed metallic oxide particles 120 such that the produced metallic oxide agglomerations 410 do not have substantially the same chemical composition as the provided fumed metallic oxide particles 110.
• the doping step may comprise selecting the liquid carrier 130 such that the produced metallic oxide agglomerations 410 do not have substantially the same chemical composition as the provided fumed metallic oxide particles 110 but rather are altered by the introduction or one or more substances.
• the solution of suspended fumed metallic oxide particles 120 may be doped with a doping agent.
• doping agent refers to an element or molecule inserted into or onto a substance to alter the chemical, electrical, or optical properties of the substance.
• the doping may result in that the produced metallic oxide agglomerations 410 may not have substantially the same chemical composition as the provided fumed metallic oxide particles 110.
• the doping agent may comprise a trace impurity inserted in very low quantities to alter the chemical, electrical, or optical properties of the produced metallic oxide agglomerations 410.
• the liquid carrier 130 may comprise one or more doping agents, such as two or more or three or more doping agents.
• the doping step may comprise introducing a carrier gas to the solution of suspended fumed metallic oxide particles 120 such that the produced metallic oxide agglomerations 410 do not have substantially the same chemical composition as the provided fumed metallic oxide particles 110.
• one or more carrier gases may be introduced to the solution of suspended fumed metallic oxide particles 120 to dope the produced metallic oxide agglomerations 410.
• the gases could include, but are not limited to, nitrogen, silane, phosgene, or combinations thereof.
• Solid doping agents could include, for example, semiconducting quantum dots or other colloidal nanoparticles.
• Liquid doping agents could include dissolved metal salts, such as AgN0 3 , NaCl, or A1(N0 3 ) 3 .
• the solution of suspended fumed metallic oxide particles 120 is shown enclosed in a container 115.
• the container 115 is not required but may facilitate the combining of the fumed metallic oxide particles 110 and the liquid carrier 130.
• the container 115 may be a beaker or flask if the method is conducted on a smaller scale or may be a barrel, drum, vat, or reactor if the method is conducted on a larger, industrial scale.
• the solution of suspended fumed metallic oxide particles 120 may comprise from about 2 wt% to about 8 wt% fumed metallic oxide particles 110.
• the solution of suspended fumed metallic oxide particles 120 may comprise from about 4 wt% to about 8 wt%, or from about 3 wt% to about 8 wt%, or from about 2 wt% to about 7 wt%, or from about 3 wt% to about 6 wt%, or from about 4 wt% to about 7 wt%, or from about 5 wt% to about 7 wt% fumed metallic oxide particles 110 suspended in the liquid carrier 130.
• the solution of suspended fumed metallic oxide particles 120 may comprise about 6 wt% fumed metallic oxide particles 110, or may comprise about 1.5 wt%, or about 2 wt%, or about 3 wt%, or about 5 wt%, or about 7 wt%, or about 10 wt%, or about 12 wt% fumed metallic oxide particles 110.
• the method may include atomizing the solution of suspended fumed metallic oxide particles 120 to produce metallic oxide-containing droplets 220.
• an atomizer 210 may atomize the suspended fumed metallic oxide particles 120 to produce metallic oxide-containing droplets 220.
• the atomizer 210 may be an aerosolizer, a spray dryer, a spray nozzle, an ultrasonic transducer, a nebulizer, an aerosol spray, or other atomizing means.
• the atomizing step 205 may comprise aerosolizing, spray drying, using an ultrasonic transducer, or any combination thereof, to produce the metallic oxide-containing droplets 220.
• atomization may comprise injecting a carrier gas into the solution of suspended fumed metallic oxide particles 120.
• the carrier gas may, in some embodiments, be selected from the group consisting of nitrogen, argon, air, helium or combinations thereof.
• the carrier gas may be one or more inert gases or a combination of gases.
• the carrier gas could contain one or more reactive gases.
• the atomized metallic oxide-containing droplets 220 may be characterized by a droplet diameter of from about 250 nm to about 100 micrometers ( ⁇ ). In other embodiments, the metallic oxide-containing droplets 220 may have a droplet diameter of from about 250 nm to about 50 ⁇ , or from about 250 nm to about 10 ⁇ , or from about 250 nm to about 1 ⁇ , or from about 250 nm to about 500 nm.
• the metallic oxide-containing droplets 220 may have a droplet diameter of from about 300 nm to about 50 ⁇ , or from about 500 nm to about 50 ⁇ , or from about 1 ⁇ to about 50 ⁇ , or from about 5 ⁇ to about 50 ⁇ , or from about 15 ⁇ to about 50 ⁇ .
• the metallic oxide-containing droplets 220 may have a droplet diameter of from about 300 nm to about 5 ⁇ , or from about 500 nm to about 5 ⁇ , or from about 1 ⁇ to about 25 ⁇ , or from about 250 nm to about 500 nm, or from about 250 nm to about 750 nm.
• the droplet size may be central to the rearrangement of the fumed metallic oxide particles 110.
• the metallic oxide-containing droplets 220 may need to be large enough to permit the fumed metallic oxide particles 110 to rearrange, but cannot be too large such that the fumed metallic oxide particles 110 are spaced too far apart from one another, which may require large amounts energy to move or rearrange the fumed metallic oxide particles 110.
• the metallic oxide-containing droplets 220 may be characterized by a fumed metallic oxide particle 110 weight percentage of from about 2 wt% to about 8 wt%.
• the fumed metallic oxide particles 110 may alternatively comprise from about 4 wt% to about 8 wt%, or from about 3 wt% to about 8 wt%, or from about 2 wt% to about 7 wt%, or from about 3 wt% to about 7 wt%, or from about 4 wt% to about 7 wt%, or from about 5 wt% to about 7 wt% fumed metallic oxide particles 110.
• the metallic oxide-containing droplets 220 may comprise about 6 wt% fumed metallic oxide particles 110, or may comprise about 2 wt%, or about 3 wt%, or about 6 wt%, or about 7 wt%, or about 10 wt%, or about 12 wt% fumed metallic oxide particles 110.
• the amount of fumed metallic oxide particles 110 in the metallic oxide-containing droplets 220 may be important to producing the metallic oxide agglomerations 410, as too many fumed metallic oxide particles 110 may not properly rearrange into a globular morphology due to the increased amount of energy required to rearrange the fumed metallic oxide particles 110. Likewise, too few fumed metallic oxide particles 110 may not be sufficient to rearrange into a globular morphology and therefore may remain branched and substantially unchanged from the starting fumed metallic oxide particles 110.
• the metallic oxide-containing droplets 220 may be subjected to a temperature of from about 50° C to about 1500° C for a period of time of at least about 0.5 seconds to substantially remove the liquid carrier 130 from the metallic oxide- containing droplets 220 to produce metallic oxide agglomerations 410.
• the subjecting may be a drying step 305 in which the liquid carrier 130 is removed.
• the metallic oxide-containing droplets 220 may be subjected to heat 308 at a temperature of from about 50° C to about 1400° C, or from about 50° C to about 1200° C, or from about 50° C to about 1000° C.
• the metallic oxide-containing droplets 220 may be subjected to heat 308 at a temperature of at least about 800° C, at least about 850° C, at least about 900° C, at least about 1000° C, or at least about 1200° C.
• the metallic oxide-containing droplets 220 may, in some embodiments, be subjected to a temperature of from about 800° C to about 1500° C, or from about 850° C to about 1500° C, or from about 850° C to about 1200° C, or from about 650° C to about 1400° C, or from about 450° C to about 1400° C, or from about 250° C to about 1400° C, or from about 150° C to about 1400° C.
• the temperature range in which the metallic oxide-containing droplets 220 are subjected to may be novel, as typically, fumed metallic oxide particles 110 are not processed at high temperatures, as they may crystallize or sinter, generating a typically irreversible crystalline compound, which may not exhibit an increased BET surface area due to the highly ordered nature of crystalline structures or the reduced surface area of a more spherically sintered particle.
• the present method may include drying the metallic oxide-containing droplets 220 at extremely high temperatures without risk of crystallization, due to the unique step of atomization, the metallic oxide- containing droplet 220 size, the concentration of fumed metallic oxide particles 110 in each metallic oxide-containing droplet 220, and the amount of time and temperature used to dry the liquid carrier 130 from the metallic oxide-containing droplets 220.
• the metallic oxide-containing droplets 220 may be subjected to the temperature for a period of time of at least about 0.5 seconds, 1 second, or at least about 2 seconds, or at least about 3 seconds, or at least about 5 seconds, or at least about 30 seconds, or at least about 1 minute.
• the metallic oxide-containing droplets 220 may be subjected to the temperature for a period of time of at least about 2 minutes, or at least about 3 minutes, or at least about 5 minutes. The amount of time required may depend on the temperature used and the size of the droplets produced. In some embodiments, the metallic oxide-containing droplets 220 may be subjected to the temperature for a period of time of at least about 0.5 seconds to allow the fumed metallic oxide particles 110 to rearrange inside the metallic oxide-containing droplets 220, which may not occur if heat 308 is applied for less than 0.5 seconds, such as flash heat.
• the metallic oxide- containing droplets 220 may comprise fumed metallic oxide particles 110, which may rearrange inside of the metallic oxide-containing droplets 220 when subjected to the previously-mentioned temperature range.
• metallic oxide agglomerations 410 may form, which may be dominantly globular in morphology.
• "dominant globular morphology” refers to a particle that is free of branched portions greater than about 5 nm and which exhibits a rounded shape at the majority of the dimensional surface extremities of the particle.
• substantially all of the produced metallic oxide agglomerations 410 may exhibit a dominant globular morphology and a BET surface area that is at least about 75% of the BET surface area of the BET surface area of the fumed metallic oxide particles 110.
• the metallic oxide agglomerations 410 may exhibit a BET surface area that is at least about 80% of the BET surface are of the fumed metallic oxide particles 110, or at least about 85%, or at least about 90%, or at least about 95%. Due to their dominantly globular morphology, the produced metallic oxide agglomerations 410 may have a reduced propensity to aerosolize when compared to the fumed metallic oxide particles 110.
• the metallic oxide agglomerations 410 may not pose a serious inhalation risk and may be easier to handle and process without incurring additional health risks.
• the metallic oxide agglomerations 410 may retain the amorphous chemistry of the fumed metallic oxide particles 110 such that the chemical composition and purity and the properties of the fumed metallic oxide particles 110 are substantially maintained in the produced metallic oxide agglomerations 410.
• the method may further comprise a collecting step 405 in which the metallic oxide agglomerations 410, or at least a majority of the produced metallic oxide agglomerations 410, are collected by filtration, condensation, or other means. It should be understood that the collecting step 405 may not be necessary in one or more embodiments.
• the metallic oxide agglomerations 410 may be collected with a filter 420.
• the filter 420 may comprise a bag filter, a vacuum filter, a sieve, a membrane, or any other means of separating and collecting the metallic oxide agglomerations 410.
• the filter 420 is depicted as conical in nature, which may be representative of a Biichner or Hirsch funnel, it should be understood that the filter 420 may comprise any size or shape known to those skilled in art.
• the metallic oxide agglomerations 410 may be collected via condensation, such as through a condensation collector, through impaction, or through a cyclone separator.
• the processing method may be substantially reversible, such that the metallic oxide agglomerations 410 may be reverted back into a solution of suspended fumed metallic oxide particles 120.
• the method may comprise redispersing the metallic oxide agglomerations 410 in the liquid carrier 130 to form a solution of suspended fumed metallic oxide particles 120.
• the liquid carrier 130 may, in some embodiments, comprise water, solvent, or a mixture of multiple liquids. As discussed above, the liquid carrier 130 may be an organic or inorganic solvent.
• FIG. 2 is a magnified schematic view of a method for processing fumed metal oxides according to embodiments shown and described herein.
• FIG. 2 depicts rearrangement steps 315, 325, 335 of the metallic oxide-containing droplets 220 as the fumed metallic oxide particles 110 rearrange to produce the metallic oxide agglomerations 410.
• the metallic oxide-containing droplets 220 may be any shape, such as spherical in nature.
• the rearrangement steps 315, 325, 335 may occur after the atomization step 205, shown in FIG. 1.
• the fumed metallic oxide particles 110 may be dispersed in the liquid carrier 130. Following atomization, the fumed metallic oxide particles 110 may begin to undergo a first rearranging step 315. In some embodiments, the first rearranging step 315 may begin upon subjecting the metallic oxide-containing droplets 220 to a temperature of from about 50° C to about 1500° C, as discussed above. Without being bound by theory, in the first rearranging step 315, the fumed metallic oxide particles 110 may begin to rearrange and densify.
• the metallic oxide-containing droplets 220 may undergo a second rearranging step 325 and even may undergo a final rearranging step 335 to further rearrange before undergoing a densifying step 345 into a globular morphology.
• the liquid carrier 130 may be substantially removed during the densifying step 345, or after the densifying step 345.
• the liquid carrier 130 may be removed from the metallic oxide-containing droplets 220 through evaporation, which may include applying heat 308 to the metallic oxide-containing droplets 220.
• the metallic oxide-containing droplets 220 may be vaporized, chemically or physically separated from the produced metallic oxide agglomerations 410, or, in some embodiments, may be further reacted to form gaseous species.
• the removal of the liquid carrier 130 is represented in FIG. 2 by dashed lines.
• a metallic oxide agglomeration 410 may be produced.
• the concentric circular lines on the metallic oxide agglomeration 410 shown in FIG. 2 are used to depict the globular morphology of the metallic oxide agglomerations 410.
• the rearrangement steps 315, 325, 335 may occur simultaneously and are merely depicted as separate formation steps for ease in understanding the rearrangement process.
• FIG. 3 is a schematic view of a method for processing fumed metal oxides according to embodiments shown and described herein, depicted as a larger-scale, industrialized process.
• a solution of suspended fumed metallic oxide particles 120 may be contained in a container 115.
• the solution of suspended fumed metallic oxide particles 120 may be atomized by an atomizer 210 to produce metallic oxide- containing droplets 220.
• a carrier 235 may be injected into the solution of suspended fumed metallic oxide particles 120 to propel the solution through the atomizer 210.
• the carrier 235 may be injected air, a liquid aerosol, or a carrier gas, such as helium, argon, air, or nitrogen gas. While hydrogen gas may be suitable, it may not be desired due to explosion concerns.
• the metallic oxide- containing droplets 220 may continue to a drier 318, to a heater 328, or to both.
• the drier 318 may only provide air at about ambient room temperature (such as at about 21° C), unlike the heater 328, which may supply heat 308 to remove solvent from the metallic oxide-containing droplets 220.
• the heater 328 may be a tube furnace in which one or more heating coils 330 may be used to generate heat 308.
• the subjecting step may comprise passing the metallic oxide-containing droplets 220 through a tube furnace.
• the metallic oxide-containing droplets 220 may be passed through a furnace at a flow rate of from about 0.1 liters per minute (L/min) to about 500 L/min.
• the flow rate may be from about 1 L/min to about 5 L/min, or from about 3 L/min to about 25 L/min.
• the flow rate may be about 5 L/min, about 25 L/min, about 50 L/min, about 100 L/min, about 250 L/min, or about 500 L/min.
• the heater 328 may, in some embodiments, use electric heating, infrared heating, convection heating, immersion heating, hydraulic heating, or other heating means.
• a carrier 235 may be used to propel the metallic oxide- containing droplets 220 through the drier 318, the heater 328, or both.
• the carrier 235 may be a carrier gas, as discussed above, which may comprise nitrogen, helium, hydrogen, argon, air, combinations thereof, or other inert or reactive gases.
• the carrier 235 may be injected into the solution of suspended fumed metallic oxide particles 120, the metallic oxide-containing droplets 220, or both. In some embodiments, the injection of a carrier 235 may aid in the movement of the particles throughout the processing components.
• a vacuum 437 may alternatively or additionally be applied to propel the metallic oxide-containing droplets 220 through the drier 318, the heater 328, or to a filter 420, which may collect the metallic oxide agglomerations 410.
• the metallic oxide agglomerations 410 may not be filtered but may be collected through other means.
• FIG. 4 is a magnified schematic view of a method for processing fumed metal oxides, according to embodiments shown and described herein.
• FIG. 4 shows three metallic oxide-containing droplets 220 undergoing a drying step 305.
• FIG. 4A depicts the drying step 305 occurring at a temperature and for an amount of time according to embodiments shown and described herein, such as the temperature and time ranges discussed above in reference to FIG. 1, which successfully produces a metallic oxide agglomerations 410.
• FIG. 4B depicts a method in which the metallic oxide-containing droplet 220 undergoes drying step 305 too quickly, or at too high of a temperature.
• the metallic oxide-containing droplet 220 in FIG. 4B may be dried for less than 0.5 seconds, or at a temperature above 1500° C, such as being subjected to flash heat. Because the liquid carrier 130 is dried too quickly, the fumed metallic oxide particles 110 do not have sufficient time to rearrange and coalesce into the desired metallic oxide agglomerations 410.
• the metallic oxide agglomerations 410 may have a dominant globular morphology.
• the metallic oxide cluster 412 produced in 4B may not have a dominantly globular morphology.
• the metallic oxide cluster 412 may, in some embodiments, continue to exhibit a dominantly branched morphology that is similar to the fumed metallic oxide particles 110, with from about 5 nm to about 50 nm average primary particles.
• FIG. 4C depicts a method in which the metallic oxide-containing droplet 220 undergoing a drying step 305 at too low of a temperature.
• a temperature such as a temperature of less than about 50° C
• the fumed metallic oxide particles 110 in the metallic oxide-containing droplet 220 may rearrange at too slow of a rate.
• the lowered temperature may cause the liquid carrier 130 to not be fully removed, causing the fumed metallic oxide particles 110 to remain as a suspension.
• these metallic oxide clusters 412 may not exhibit or retain a globular structure and the metallic oxide clusters 412 reverts to its original geometry of the fumed metallic oxide particles 110. While some densification may occur, the metallic oxide cluster 412 produced may not have as pronounced of a globular morphology or as high of a bulk density as compared to the desired metallic oxide agglomerations 410.
• FIG. 5 is a magnified schematic view of a method for processing fumed silica.
• FIG. 5 shows the importance of the concentration of fumed silica particles 111 within the silica-containing droplet 221, as previously discussed. While FIG. 5 depicts silica, it should be understood that any metallic or bi-metallic oxide may be used.
• FIG. 5A depicts three silica-containing droplets 221 undergoing a drying step 305. As shown in FIG.
• silica-containing droplet 221 does not comprise fumed silica particles 111 that are sufficiently branched, such as fumed silica particles 111 with a primary particle size of from about 5 nm to about 50 nm, as previously discussed, silica agglomerations 411 may not be produced. Instead, a silica cluster 412 may form, as shown in FIG. 5A, which may not exhibit a globular morphology but instead may retain the branched morphology of the original fumed silica particles 111, or as shown in FIG. 5B, a silica nanoparticle aggregate 414 may form, which may not retain a high BET surface area. [00049] In FIG. 5B, like FIG.
• silica agglomerations 411 may not be produced. Instead, silica nanoparticle aggregates 414 may be produced, which do not exhibit a desirable BET surface area, but instead, may be smooth nanoscale particles with little BET surface area. Without retaining a desirable BET surface area, such as a BET surface area of at least about 75% of the BET surface area of the starting fumed silica particles 111 as the produced silica agglomerations 411 exhibit, the produced silica nanoparticle aggregates 414 may not be commercially desirable.
• FIG. 5C depicts the production of a silica agglomerations 411 produced by the methods shown and described herein.
• fumed silica particles 111 are provided, wherein the fumed silica particles 111 have a BET surface area of greater than about 50 meters m /g and are characterized by a dominant branched morphology comprising from 5 nm to 50 nm primary particles, with an average bulk density of less than 64 kilograms per cubic meter (kg/m ).
• the fumed silica particles 111 may be characterized by an average bulk density of less than 64 kilograms per cubic meter (kg/m ) which is equivalent to about 4 pounds per cubic foot (lbs/ft ).
• average bulk density refers to the average weight of a unit volume of a loose material, such as the metallic oxide particles, to the same volume of water in kilograms per cubic meter (kg/m ) or pounds per cubic foot (lbs/ft ).
• the fumed silica particles 111 may have an average bulk density of less than 60 kg/m 3 , or less than 55 kg/m 3 , or less than 50 kg/m 3 , or less than 45 kg/m 3 , or less than 30 kg/m .
• the fumed metallic oxide particles 110 may have an average bulk density of from 45 kg/m 3 to 64 kg/m 3 , or from 45 kg/m 3 to 60 kg/m 3 , or from 45 kg/m 3 to 55 kg/m 3 , or from 30 /m 3 to 64 kg/m 3 , or from 30 /m 3 to 60 kg/m 3 , or from 30 /m 3 to 55 kg/m 3 , or from 30
• the fumed silica particles 111 may have an average bulk density of less than 3 lbs/ft 3 , less than 2 lbs/ft 3 , or less than 1 lbs/ft 3.
• the bulk density of the starting fumed silica particles 111 may provide sufficient branching, and thus, increased BET surface area, as discussed above. If the starting fumed silica particles 111 have too high of an average bulk density, such as an average bulk density over about 64 kg/m , the fumed metallic oxide particles 110 may be too compacted to properly rearrange and coalesce into the desired silica agglomerations 411. [00051] Again referring to FIG.
• the fumed silica particles 111 may be combined with a liquid carrier 130 to form a solution of suspended fumed silica particles 121.
• the solution of suspended fumed silica particles 121 may comprise from about 2 wt% to about 8 wt% of the fumed silica particles 111 and may be atomized to produce silica-containing droplets 221. At least a majority of the silica-containing droplets 221 may be characterized by a droplet diameter of about 250 nm to about 100 ⁇ and a fumed silica particle 111 weight percentage of from about 2 wt% to about 8 wt%.
• the silica-containing droplets 221 may be subjected to a temperature of from about 50° C to about 1500° C for a period of time of at least about 0.5 seconds to substantially remove the liquid carrier 130 from the silica-containing droplets 221 to produce the silica agglomerations 411.
• Substantially all of the produced silica agglomerations 411 may exhibit a BET surface area that is at least about 75% of the BET surface area of the fumed silica particles 111 and a dominant globular morphology characterized by an average bulk density of greater than 64 kg/m .
• FIGS. 6A to 6F are scanning electron microscope (SEM) images of fumed silica particles 111 before processing in accordance with the methods shown and described herein, as well as produced silica agglomerates 411 produced by the methods shown and described herein.
• FIGS. 6A and 6B are SEM images of fumed silica particles 111. It should be understood that while fumed silica particles 111 are depicted, any fumed metallic oxide particles 110 may be used. As shown in FIGS. 6A and 6B, the fumed silica particles 111 are extremely fractal and are highly branched.
• the branched nature of the fumed silica particles 111 may create a "dusty" environment, as the particles are easily aerosolized, which may create an inhalation hazard.
• the propensity to aerosolize may be exacerbated by the potential for the fumed silica particles 111 to break down into their primary nanoscale particles, particularly when exposed to surfactants and liquid forces, such as those in the human body and, more particularly, the lungs.
• the dusty nature of the fumed silica particles 111 may pose serious health risks during handling and transporting the fumed silica particles 111 and steps may need to be taken to reduce inhalation hazards, such as requiring individuals in the area to wear masks.
• FIGS. 6C, 6D, 6E and 6F show the drastic morphological effects of the methods of processing fumed silica according to embodiments shown and described herein.
• the produced silica agglomerations 411 have a dominantly globular morphology.
• the SEM images of FIGS. 6C, 6D, 6E and 6F further depict the ability of the produced silica agglomerations 411 to retain at least a high portion of the BET surface area of the starting fumed silica particles 111, as the silica agglomerations 411 may not smooth so as to provide an increased BET surface area.
• Fumed silica (silicon oxide, Si0 2 ) was processed according to embodiments shown and described herein to produce silica agglomerates with a globular morphology. As depicted in Table 1, below, fumed silica commercially available from Evonik and Strem Chemicals was mixed with deionized water to form a solution of suspended fumed silica particles. The solution was atomized using an ultrasonic transducer. The droplet size was varied to produce the desired %wt of solid fumed silica particles present in the droplets. The droplets were dried to remove the deionized water at varying residence times and flow rates by flowing the liquid aerosol through a tube furnace for the time and temperatures listed below.
• the BET surface area of Evonik and Strem fumed silica is listed as being around 200 m /g, however the BET of the starting fumed silica particles were measured to be between 207 and 214 m /g.
• the highest measured value of 214 m /g was used to ensure accuracy.
• All of the resulting silica agglomerations were characterized as amorphous by x-ray diffraction analysis. Notably, as shown below in Table 3, the resulting silica agglomerates all retained extraordinarily high BET surface areas, with some samples within over 90% BET surface area retention.
• fumed alumina was also processed according to embodiments of the methods shown and described herein.
• Fumed alumina commercially available from Evonik Chemicals was mixed with deionized water to form a solution of suspended fumed alumina particles. The solution was atomized using an ultrasonic transducer. The droplet size was varied to produce the desired %wt of solid fumed alumina particles present in the droplets. The droplets were dried to remove the deionized water at varying residence times and flow rates by flowing the liquid aerosol through a tube furnace for the time and temperatures listed below. All of the resulting alumina agglomerations were characterized as amorphous by x-ray diffraction analysis. Notably, as shown below in Table 3, the resulting alumina agglomerates all retained extraordinarily high BET surface areas, with some samples within over 90% BET surface area retention. [00060] Table 2: Processing of Fumed Alumina into Alumina Agglomerates
• fumed metallic oxides were also processed according to embodiments of the methods shown and described herein.
• Fumed alumina commercially available from Evonik Chemicals
• fumed silica commercially available from Sigma Aldrich and Evokik Chemicals
• the solution was atomized using an ultrasonic transducer.
• the droplet size was varied to produce the desired %wt of solid fumed mixed oxide particles present in the droplets.
• the droplets were dried to remove the deionized water at varying residence times and flow rates by flowing the liquid aerosol through a tube furnace for the time and temperatures listed below.
• the methods of the present disclosure may allow for the production of metallic oxide agglomerations that exhibit a dominantly globular morphology to reduce the inhalation risks presented by fumed metallic oxide particles, but retain the desired properties of their fumed counterparts, such as a high BET surface area.
• the produced metallic oxide agglomerates may have a BET surface area retention of at least about 75%, at least about 80%, at least about 85%, at least about 90%, or even at least about 95%.
• a first aspect of the disclosure is directed to a method for processing fumed silica into silica agglomerations comprising: providing fumed silica particles, wherein the fumed silica particles have a first Brunauer Emmett Teller (BET) surface area of greater than about 50 meters squared per gram (m /g), and are characterized by a dominant branched morphology comprising from 5 nanometer (nm) to 50 nm primary particles, with an average bulk density of less than 64 kilograms per cubic meter (kg/m ); combining the fumed silica particles with a liquid carrier to form a solution of suspended fumed silica particles, wherein the solution of suspended fumed silica particles comprises from about 2 weight percent (wt%) to about 8 wt% of the fumed silica particles; atomizing the solution of suspended fumed silica particles to produce silica-containing droplets, wherein at least a majority of the silica-containing droplets are characterized by a droplet diameter of about
• a second aspect of the disclosure includes the first aspect, wherein the method further comprises collecting at least a majority of the produced silica agglomerations by filtration or condensation.
• a third aspect of the disclosure includes the first aspect, wherein the atomizing step comprises aerosolizing, spray drying, using an ultrasonic transducer, or any combination thereof, to produce the silica-containing droplets.
• a fourth aspect of the disclosure includes the first aspect, wherein the atomizing step comprises injecting a carrier gas into the solution of suspended fumed silica particles.
• a fifth aspect of the disclosure includes the fourth aspect, wherein the carrier gas is selected from the group consisting of nitrogen, air, or combinations thereof.
• a sixth aspect of the disclosure includes the first aspect, wherein the liquid carrier is selected such that the produced silica agglomerations have substantially the same chemical composition as the provided fumed silica particles, wherein the produced silica agglomerations are comprised of less than about 2 wt% of impurities.
• a seventh aspect of the disclosure includes the first aspect, wherein the liquid carrier is comprised of H 2 0.
• An eighth aspect of the disclosure includes the first aspect, wherein the method comprises doping the solution of suspended fumed silica particles such that the produced silica agglomerations do not have substantially the same chemical composition as the provided fumed silica particles.
• a ninth aspect of the disclosure includes the eighth aspect, wherein the doping step comprises selecting the liquid carrier such that the produced silica agglomerations do not have substantially the same chemical composition as the provided fumed silica particles.
• a tenth aspect of the disclosure includes the eighth aspect, wherein the doping step comprises introducing a carrier gas to the solution of suspended fumed silica particles such that the produced silica agglomerations do not have substantially the same chemical composition as the provided fumed silica particles.
• An eleventh aspect of the disclosure includes the first aspect, wherein the fumed silica particles have a first BET surface area from about 200 m 2 /g to about 600 m 2 /g.
• a twelfth aspect of the disclosure includes the first aspect, wherein substantially all of the produced silica agglomerations exhibit a second BET surface area that is at least about 90% of the first BET surface area.
• a thirteenth aspect of the disclosure includes the first aspect, wherein the silica- containing droplets comprise from about 3 wt% to about 6 wt% of fumed silica particles.
• a fourteenth aspect of the disclosure includes the first aspect, wherein the solution of suspended fumed silica particles comprises from about 3 wt% to about 6 wt% of fumed silica particles.
• a fifteenth aspect of the disclosure includes the first aspect, wherein the silica- containing droplets comprise about 6 wt% of fumed silica particles.
• a sixteenth aspect of the disclosure includes the first aspect, wherein the solution of suspended fumed silica particles comprises about 6 wt% of fumed silica particles.
• a seventeenth aspect of the disclosure includes a the first aspect, wherein the silica-containing droplets are subjected to a temperature of from about 400° C to about 1500° C.
• An eighteenth aspect of the disclosure includes the first aspect, wherein the subjecting step comprises passing the silica-containing droplets through a tube furnace.
• a nineteenth aspect of the disclosure includes the eighteenth aspect, wherein the subjecting step comprises passing the silica-containing droplets through a tube furnace at a flow rate of from about 3 liters per minute (L/min) to about 50 L/min.
• a twentieth aspect of the disclosure includes the first aspect, wherein the method is substantially reversible, such that the silica agglomerations may be reverted into a solution of suspended fumed silica particles.
• a twenty-first aspect of the disclosure includes the first aspect, further comprising, redispersing the silica agglomerations into the liquid carrier to form a solution of suspended fumed silica particles, wherein the solution of suspended fumed silica particles comprises from about 2 wt% to about 8 wt% of fumed silica particles.
• a twenty-second aspect of the disclosure is directed to a method for processing fumed metallic oxides comprising: providing fumed metallic oxide particles, wherein the fumed metallic oxide is selected from the group consisting of Si0 2 , A1 2 0 3 , Ti0 2 , Ce0 2 , B 2 0 3 , Zr0 2 , Ge0 2 , W0 3 , Nb 2 Os, and combinations thereof, wherein the fumed metallic oxide particles have a first Brunauer Emmett Teller (BET) surface area of greater than about 50 m /g, and a dominant branched morphology comprising from 5 nm to 50 nm primary particles; combining the fumed metallic oxide particles with a liquid carrier to form a solution of suspended fumed metallic oxide particles, wherein the solution of suspended fumed metallic oxide particles comprises from about 2 wt% to about 8 wt% of the fumed metallic oxide particles; atomizing the solution of suspended fumed metallic oxide particles to produce metallic oxide-containing droplets, wherein at least a majority
• a twenty-third aspect of the disclosure includes the twenty-second aspect, wherein the fumed metallic oxide particles are fumed alumina (AI 2 O 3 ) particles and the produced metallic oxide agglomerations are alumina agglomerations.
• a twenty-fourth aspect of the disclosure includes the twenty-third aspect, wherein the fumed alumina particles have a first BET surface area from about 80 m /g to about 150 m 2 /g.
• a twenty-fifth aspect of the disclosure includes the twenty-third aspect, wherein the fumed alumina particles have an average bulk density of less than 60 kg/m and the produced alumina agglomerations have an average bulk density of greater than 40 kg/m .
• a twenty-sixth aspect of the disclosure includes the twenty-second aspect, wherein the fumed metallic oxide is silica (Si0 2 ).
• a twenty- seventh aspect of the disclosure includes the twenty-second aspect, wherein the fumed metallic oxide is a mixed oxide comprising at least two metallic oxides selected from the group consisting of Si0 2 , A1 2 0 3 , Ti0 2 , Ce0 2 , B 2 0 3 , Zr0 2 , Ge0 2 , W0 3 , and Nb 2 0 5 .
• a twenty-eight aspect of the disclosure is directed to a method for processing fumed silica into silica agglomerations comprising: providing fumed silica particles, wherein the fumed silica particles have a first Brunauer Emmett Teller (BET) surface area of from about 200 m 2 /g to about 600 m 2 /g, and are characterized by a dominant branched morphology comprising from 5 nm to 50 nm primary particles, with an average bulk density of less than 64 kilograms per cubic meter (kg/m ); combining the fumed silica particles with a liquid carrier to form a solution of suspended fumed silica particles, wherein the solution of suspended fumed silica particles comprises from about 2 weight percent (wt%) to about 8 wt% of the fumed silica particles; atomizing the solution of suspended fumed silica particles to produce silica-containing droplets, wherein at least a majority of the silica-containing droplets are characterized by a droplet

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