# US 8,771,404 B2 · Hollow ceramic fibers, precursors for manufacture thereof utilizing nanoparticles, methods of making the same, and methods of using the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,771,404 B2 - Document ID: US8771404B2 - Status: Granted - Kind: B2 - Application number: 13/194,990 - Filed: 2011-07-31 - Published: 2013-01-31 - Granted: 2014-07-08 - Earliest claimed: 2011-07-31 - Assignees: L'Air Liquide, Societe Anonyme pour l'Etude et l'Exploitation des Procedes Georges Claude - Applicants: Tao Li; Taekyu Kang - Inventors: Tao Li; Taekyu Kang - Web page: https://patentgrep.com/patent/US8771404B2 ## CPC - B01D 53/228: {characterised by specific membranes} - B01D 67/00411: {by sintering} - B01D 67/0079: {Manufacture of membranes comprising organic and inorganic components} - B01D 69/088: {Co-extrusion; Co-spinning} - B01D 69/1213: {Laminated layers} - B01D 71/0271: {Perovskites} - B82Y 30/00: Nanotechnology for materials or surface science, e.g. nanocomposites - C01B 3/503: characterised by membranes - C01B 3/505: Membranes containing palladium - C01B 13/0255: {characterised by the type of membrane} - C04B 20/0056: {Hollow or porous fibres} - C04B 20/0068: {Composite fibres, e.g. fibres with a core and sheath of different material} - C04B 35/2633: {containing barium, strontium or calcium} - C04B 35/2641: {Compositions containing one or more ferrites of the group comprising rare earth metals and one or more ferrites of the group comprising alkali metals, alkaline earth metals or lead} - C04B 35/62227: {obtaining fibres} - C04B 35/62231: {based on oxide ceramics} - C04B 35/6225: {Fibres based on zirconium oxide, e.g. zirconates such as PZT} - C04B 35/62259: {Fibres based on titanium oxide} - C04B 35/6263: {characterised by their solids loadings, i.e. the percentage of solids} - C04B 35/62847: {with oxide ceramics} - C04B 35/62897: {Coatings characterised by their thickness} - C04B 38/067: {Macromolecular compounds (C04B38/062 takes precedence)} - D01D 5/24: with a hollow structure; Spinnerette packs therefor (D01D5/38 takes precedence; producing tubes of plastic material B29D; addition of agents forming hollow filaments D01F1/08) - D01D 5/34: Core-skin structure; Spinnerette packs therefor - D01F 9/10: by decomposition of organic substances (D01F9/12 takes precedence) - B01D 2323/12: Specific ratios of components used - B01D 2323/20: Plasticizers - C01B 2203/025: containing a partial oxidation step - C04B 2235/3208: Calcium oxide or oxide-forming salts thereof, e.g. lime - C04B 2235/3213: Strontium oxides or oxide-forming salts thereof - C04B 2235/3215: Barium oxides or oxide-forming salts thereof - C04B 2235/3217: Aluminum oxide or oxide forming salts thereof, e.g. bauxite, alpha-alumina - C04B 2235/3224: Rare earth oxide or oxide forming salts thereof, e.g. scandium oxide - C04B 2235/3227: Lanthanum oxide or oxide-forming salts thereof - C04B 2235/3229: Cerium oxides or oxide-forming salts thereof - C04B 2235/3234: Titanates, not containing zirconia - C04B 2235/3255: Niobates or tantalates, e.g. silver niobate - C04B 2235/3274: Ferrites - C04B 2235/3275: Cobalt oxides, cobaltates or cobaltites or oxide forming salts thereof, e.g. bismuth cobaltate, zinc cobaltite - C04B 2235/3286: Gallium oxides, gallates, indium oxides, indates, thallium oxides, thallates or oxide forming salts thereof, e.g. zinc gallate - C04B 2235/5264: characterised by the diameter of the fibers - C04B 2235/5284: Hollow fibers, e.g. nanotubes - C04B 2235/5436: micrometer sized, i.e. from 1 to 100 micron - C04B 2235/5454: nanometer sized, i.e. below 100 nm - C04B 2235/6021: Extrusion moulding - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) - B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES - C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C} - C04B: LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE {(roofing granules E04D7/005)}; CERAMICS (devitrified glass-ceramics C03C10/00); REFRACTORIES; TREATMENT OF NATURAL STONE - D01D: MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS - D01F: CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS ## Abstract A composite hollow ceramic fiber includes a porous hollow core supporting a thin, dense sheath. The non-gas-tight core comprises a first ceramic material and an interconnecting network of pores. The gas-tight sheath comprises a second ceramic material. The fiber is made by extruding a core suspension of particles of the first ceramic material, a polymeric binder, and a solvent and a sheath suspension of particles of the second ceramic material, a polymeric binder and a solvent, respectively, from a spinnerette and coagulating the nascent hollow fiber to effect phase inversion of the polymeric binders. The resultant green fiber is sintered in a two step process. First, the binders are burned off. Second, the sheath is densified and the second ceramic material is sintered without fully sintering the first ceramic material. The first ceramic material of the core suspension has a median particle size greater than that of the second ceramic material of the sheath suspension. ## Claims ### Claim 1 A process for making a composite hollow ceramic fiber, comprising the steps of: preparing a core suspension comprising a first polymeric binder, a first particulate ceramic material, and a first solvent; preparing a sheath suspension comprising a second polymeric binder, a second particulate ceramic material, and a second solvent; providing a spinnerette adapted and configured to continuously extrude one or more nascent hollow fibers comprising a hollow core formed from the core suspension and a sheath surrounding the core formed from the sheath suspension; immersing the nascent hollow fiber in a liquid coagulant to facilitate phase inversion of the first and second polymeric binders, wherein: the second particulate ceramic material comprises a mixed oxide conductor; the second particulate ceramic material has a median particle size less than that of the first particulate ceramic material; the first and second particulate ceramic materials are chemically identical; the first and second solvents are the same or different; and the first and second polymeric binders are the same or different. ### Claim 2 (depends on 1) The process of claim 1, wherein the second particulate ceramic material in the sheath suspension has a median particle size of less than 100 nm. ### Claim 3 (depends on 1) The process of claim 1, wherein the second particulate ceramic material in the sheath suspension has a median particle size of no greater than 75 nm. ### Claim 4 (depends on 1) The process of claim 1, wherein: the core suspension further comprises an amount of the second particulate ceramic material; the second particulate ceramic material of the core suspension has a median particle size greater than that of the second particulate ceramic material of the sheath suspension such that the second particulate ceramic material of the sheath suspension is sinterable at a temperature less than that of the second particulate ceramic material of the core suspension. ### Claim 5 (depends on 4) The process of claim 4, wherein: the median particle size of the first particulate ceramic material of the core suspension is no less than 100 nm; the median particle size of the second particulate ceramic material of the core suspension is no less than 100 nm; and the median particle size of the second particulate ceramic material of the sheath suspension is no greater than 75 nm. ### Claim 6 (depends on 1) The process of claim 1, wherein: the sheath suspension further comprises an amount of the first particulate ceramic material; the first particulate ceramic material of the sheath suspension has a median particle size less than that of the first particulate ceramic material of the core suspension such that the first particulate ceramic material of the sheath suspension is sinterable at a temperature less than that of the first particulate ceramic material of the core suspension. ### Claim 7 (depends on 6) The process of claim 6, wherein the median particle size of the first particulate ceramic material of the core suspension is no less than 100 nm; the median particle size of the first particulate ceramic material of the sheath suspension is no greater than 75 nm; and the median particle size of the second particulate ceramic material of the sheath suspension is no greater than 75 nm. ### Claim 8 (depends on 1) The process of claim 1, wherein: the core suspension further comprises an amount of the second particulate ceramic material; the sheath suspension further comprises an amount of the first particulate ceramic material; the first particulate ceramic material of the sheath suspension has a median particle size less than that of the first particulate ceramic material of the core suspension such that the first particulate ceramic material of the sheath suspension is sinterable at a temperature less than that of the first particulate ceramic material of the core suspension; and the second particulate ceramic material of the core suspension has a median particle size greater than that of the second particulate ceramic material of the sheath suspension such that the second particulate ceramic material of the sheath suspension is sinterable at a temperature less than that of the second particulate ceramic material of the core suspension. ### Claim 9 (depends on 8) The process of claim 8, wherein: the median particle sizes of the first and second particulate ceramic materials of the core suspension is no less than 100 nm; and the median particle size of the first and second particulate ceramic materials of the sheath suspension is no greater than 75 nm. ### Claim 10 (depends on 1) The process of claim 1, wherein the sheath suspension comprises about 64 wt. % to about 80 wt. % of the particles of the second particulate ceramic material and about 8 wt. % to about 12 wt. % of the second polymeric binder. ### Claim 11 (depends on 1) The process of claim 1, further comprising the step of passing the nascent hollow fiber from the spinnerette through an air gap. ### Claim 12 (depends on 1) The process of claim 1, wherein the core suspension further comprises pore formers insoluble in the first solvent. ### Claim 13 (depends on 1) The process of claim 1, wherein the mixed oxide conductor comprises a hydrogen conducting mixed oxide conductor. ### Claim 14 (depends on 1) The process of claim 1, wherein the mixed oxide conductor is an oxygen conducting mixed oxide conductor. ### Claim 15 (depends on 14) The process of claim 14, wherein the oxygen conducting mixed oxide conductor is a perovskite independently selected from formula (I): [Ma1−x−uMa′xMa″u][Mb1−y−vMb′yMb″v]O3−δ (I) in which: Ma represents an atom chosen from scandium, yttrium, or from the families of lanthanides, actinides or alkaline-earth metals; Ma′, which is different from Ma, represents an atom chosen from scandium, yttrium or from the families of lanthanides, actinides or alkaline-earth metals; Ma″, which is different from Ma and Ma′, represents an atom chosen from aluminum (Al), gallium (Ga), indium (In), thallium (Tl) or from the family of alkaline-earth metals; Mb represents an atom chosen from transition metals; Mb′, which is different from Mb, represents an atom chosen from transition metals, aluminum (Al), indium (In), gallium (Ga), germanium (Ge), antimony (Sb), bismuth (Bi), tin (Sn), lead (Pb) and titanium (Ti); Mb″, which is different from Mb and Mb′, represents an atom chosen from transition metals, alkaline-earth metals, aluminum (Al), indium (In), gallium (Ga), germanium (Ge), antimony (Sb), bismuth (Bi), tin (Sn), lead (Pb) and titanium (Ti); 0