EP2916934A1 - Couche de support poreuse - Google Patents

Couche de support poreuse

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Publication number
EP2916934A1
EP2916934A1 EP13792299.3A EP13792299A EP2916934A1 EP 2916934 A1 EP2916934 A1 EP 2916934A1 EP 13792299 A EP13792299 A EP 13792299A EP 2916934 A1 EP2916934 A1 EP 2916934A1
Authority
EP
European Patent Office
Prior art keywords
layer
porous support
support layer
porous
oxygen
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP13792299.3A
Other languages
German (de)
English (en)
Inventor
Nathalie Petigny
Christos SARANTOPOULOS
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Saint Gobain Centre de Recherche et dEtudes Europeen SAS
Original Assignee
Saint Gobain Centre de Recherche et dEtudes Europeen SAS
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from US13/671,835 external-priority patent/US20130072374A1/en
Priority claimed from US13/672,975 external-priority patent/US9561476B2/en
Application filed by Saint Gobain Centre de Recherche et dEtudes Europeen SAS filed Critical Saint Gobain Centre de Recherche et dEtudes Europeen SAS
Publication of EP2916934A1 publication Critical patent/EP2916934A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/22—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by diffusion
    • B01D53/228—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by diffusion characterised by specific membranes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0039—Inorganic membrane manufacture
    • B01D67/0041—Inorganic membrane manufacture by agglomeration of particles in the dry state
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0039—Inorganic membrane manufacture
    • B01D67/0041—Inorganic membrane manufacture by agglomeration of particles in the dry state
    • B01D67/00411—Inorganic membrane manufacture by agglomeration of particles in the dry state by sintering
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/10—Supported membranes; Membrane supports
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/12—Composite membranes; Ultra-thin membranes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/02—Inorganic material
    • B01D71/024—Oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/02—Inorganic material
    • B01D71/024—Oxides
    • B01D71/0271—Perovskites
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B13/00—Oxygen; Ozone; Oxides or hydroxides in general
    • C01B13/02—Preparation of oxygen
    • C01B13/0229—Purification or separation processes
    • C01B13/0248—Physical processing only
    • C01B13/0251—Physical processing only by making use of membranes
    • C01B13/0255—Physical processing only by making use of membranes characterised by the type of membrane
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2323/00—Details relating to membrane preparation
    • B01D2323/15—Use of additives
    • B01D2323/18—Pore-control agents or pore formers

Definitions

  • the present invention relates to a porous support layer for a composite oxygen transport membrane and to a composite oxygen transport membrane in which catalyst particles, selected to promote oxidation of a combustible substance, are located within an intermediate porous layer that is in turn located between a dense layer and a porous support layer and within the porous support.
  • Oxygen transport membranes function by transporting oxygen ions through a material that is capable of conducting oxygen ions and electrons at elevated temperatures.
  • Such materials can be mixed conducting in that they conduct both oxygen ions and electrons or a mixture of materials that include an ionic conductor capable of primarily conducting oxygen ions and an electronic conductor with the primary function of transporting the electrons.
  • Typical mixed conductors are formed from doped perovskite structured materials.
  • the ionic conductor can be yttrium or scandium stabilized zirconia and the electronic conductor can be a perovskite structured material that will transport electrons, a metal or metal alloy or a mixture of the perovskite type material, the metal or metal alloy.
  • the partial pressure difference can be produced by providing the oxygen containing feed to the membrane at a positive pressure or by supplying a combustible substance to the side of the membrane opposing the oxygen containing feed or a combination of the two methods.
  • oxygen transport membranes are composite structures that include a dense layer composed of the mixed conductor or the two phases of materials and one or more porous supporting layers. Since the resistance to oxygen ion transport is dependent on the thickness of the membrane, the dense layer is made as thin as possible and therefore must be supported.
  • Another limiting factor to the performance of an oxygen transport membrane concerns the supporting layers that, although can be active, that is oxygen ion or electron conducting, the layers themselves can consist of a network of interconnected pores that can limit diffusion of the oxygen or fuel or other substance through the membrane to react with the oxygen. Therefore, such support layers are typically fabricated with a graded porosity in which the pore size decreases in a direction taken towards the dense layer or are made highly porous throughout. The high porosity, however, tends to weaken such a structure.
  • U.S. Patent No. 7,229,537 attempts to solve such problems by providing a support with cylindrical or conical pores that are not connected and an intermediate porous layer located between the dense layer and the support that distributes the oxygen to the pores within the support.
  • Porous supports can also be made by freeze casting techniques, as described in 10, No. 3, Advanced Engineering Materials, "Freeze-Casting of Porous Ceramics: A Review of Current Achievements and Issues” (2008) by Deville, pp. 155-169. In freeze casting, a liquid suspension is frozen. The frozen liquid phase is then sublimated from a solid to a vapor under reduced pressure. The resulting structure is sintered to consolidate and densify the structure.
  • porous structure having pores extending in one direction and that have a low tortuosity.
  • Such supports have been used to form electrode layers in solid oxide fuel cells.
  • a porous surface exchange layer can be located on the opposite side of the dense layer to enhance reduction of the oxygen into oxygen ions.
  • Such a composite membrane is illustrated in US Patent No. 7,556,676 that utilizes two phase materials for the dense layer, the porous surface exchange layer and the intermediate porous layer. These layers are supported on a porous support that can be formed of zirconia.
  • the oxygen partial pressure difference can be created by combusting a fuel or other combustible substance with the separated oxygen.
  • the resulting heat will heat the oxygen transport membrane up to operational temperature and excess heat can be used for other purposes, for example, heating a fluid, for example, raising steam in a boiler or in the combustible substance itself.
  • perovskite structured materials will exhibit a high oxygen flux, such materials tend to be very fragile under operational conditions such as in the heating of a fluid. This is because the perovskite type materials will have a variable stoichiometry with respect to oxygen. In air it will have one value and in the presence of a fuel that is undergoing combustion it will have another value.
  • the present invention provides a porous support layer that makes it possible to obtain a robust oxygen transport membrane.
  • the present invention may be characterized as a porous support layer comprised of an fluorite structured ionic conducting material having a porosity of greater than 20 percent and a microstructure exhibiting substantially uniform pore size distribution throughout the porous support layer, wherein the porous support layer is formed from a mixture comprising fluorite structured ionic conducting material or from a mixture comprising polymethyl methacrylate based pore forming material and a fluorite structured ionic conducting material, said polymethyl methacrylate based pore forming material and/or said fluorite structured ionic conducting material having bi-modal or multi-modal particle sizes.
  • the present invention may further be characterized as a composite oxygen transport membrane comprising (i) the above described porous support layer; (ii) an intermediate porous layer often referred to as a fuel oxidation layer disposed adjacent to the porous support layer and capable of conducting oxygen ions and electrons to separate oxygen from an oxygen containing feed and comprising a mixture of a fluorite structured ionic conductive material and electrically conductive materials to conduct the oxygen ions and electrons, respectively; (iii) a dense separation layer capable of conducting oxygen ions and electrons to separate oxygen from an oxygen containing feed, the dense layer adjacent to the intermediate porous layer and also comprising a mixture of a fluorite structured ionic conductive material and electrically conductive materials to conduct the oxygen ions and electrons, respectively; and (iv) catalyst particles or a solution containing precursors of the catalyst particles located in pores of the porous support layer and intermediate porous layer, the catalyst particles containing a catalyst selected to promote oxidation of a combustible substance in the presence of the separated
  • the catalyst is preferably gadolinium doped ceria but may also be other catalysts that promote fuel oxidation.
  • the composite oxygen transport membrane may also include a porous surface exchange layer or an air activation layer disposed or applied to the dense separation layer on the side opposite to the intermediate porous layer or the fuel oxidation layer. If used, the porous surface exchange layer or an air activation layer preferably has a thickness of between 10 and 40 microns and a porosity of between about 30 and 60 percent.
  • the intermediate porous layer or fuel oxidation layer preferably has a thickness of between about 10 and 40 microns and a porosity of between about 20 and 50 percent whereas the dense layer has a thickness of between 10 and 50 microns.
  • the porous support layer is formed from a mixture comprising, and preferably consisting essentially of, a fluorite structured ionic conducting material having a bi-modal or multimodal particle size distribution and optionally a pore forming material.
  • Fluorite structured ionic conducting material is preferably stabilized zirconia, preferably yttria stabilized zirconia, preferably zirconia comprising at least 2mol% of yttrium oxide, preferably, from 2 to 5mol% of yttrium oxide, or from 3 to 4mol% of yttrium oxide. It is understood that “stabilized zirconia” also includes “partially stabilized zirconia”.
  • the porous support layer may be formed from a mixture comprising 3mol% yttria stabilized zirconia, or 3YSZ having a bi-modal or multimodal particle size distribution, and optionally a pore forming material.
  • the pore forming material may be polymethyl methacrylate based pore forming material.
  • the pore forming material may have a bi-modal or multimodal particle size distribution.
  • the fluorite structured ionic conducting material having a bi-modal or multi-modal particle sizes comprises at least 30 weight percent of particles having a particle size greater than 2 microns and/or at least 90 weight percent of particles having a particle size below 10 microns, preferably below 8 microns or even below 7 microns.
  • Such a material may be obtained my mixing at least two powders having different median particle size.
  • the porous support layer is formed by mixing a first powder having a median particle size diameter (D50) of between 0.3 and 1.5 microns and at least a second powder having a median particle size diameter (D50) of between 2.0 and 6.0 microns.
  • the porous support layer is formed from a fluorite structured ionic conducting material and polymethyl methacrylate based pore forming material having a bi-modal or multimodal particle size distribution.
  • the porous support layer has a preferred thickness of between about 0.5 and 4 mm and porosity between about 20 and 40 percent.
  • the intermediate porous layer comprises a mixture of about 60 percent by weight of (La u Sr v Cei_ u -v) w Cr x M y V z 0 3 _6 with the remainder Zr X' Sc y A z ⁇ 0 2 -6.
  • the dense separation layer comprises a mixture of about 40 percent by weight of (La u Sr v Cei_ u -v) w Cr x M y V z 0 3 _6 with the remainder Zr X' ScyA z ⁇ 0 2 -6.
  • u is from 0.7 to 0.9
  • v is from 0.1 to 0.3 and (1-u-v) is greater than or equal to zero
  • w is from 0.94 to 1
  • x is from 0.5 to 0.77
  • M is Mn or Fe
  • y is from 0.2 to 0.5
  • A is Y or Ce or mixtures of Y and Ce.
  • one of the preferred embodiments of the composite oxygen transport membrane includes an intermediate porous layer or fuel oxidation layer that comprises about 60 percent by weight of (Lao.825Sro.i75)o. 6Cro.76Feo.225Vo.oi50 3 -6 or (La 0 .8Sro.2)o.95Cro.7Feo. 3 0 3 -6 with the remainder lOSclYSZ or lOSclCeSZ.
  • the dense separation layer comprises about 40 percent by weight of (Lao.8 2 5Sro.i75)o. 4Cro.7 2 Mno.26Vo.o20 3 _6 or (La 0 . 8 Sro.
  • the porous surface exchange layer or air activation layer is formed by a mixture of about 50 percent by weight of (La 0 .8Sro. 2 )o.98Mn0 3 _6 or La 0 .8Sro. 2 Fe0 3 _6, remainder lOSclYSZ or lOSclCeSZ.
  • the present invention may also be characterized as a product by process wherein the product is a porous support layer.
  • the process comprises: (i) fabricating a porous support layer comprised of an fluorite structured ionic conducting material, the fabricating step including pore forming enhancement step such that the porous support layer has a porosity of greater than about 20 percent and a microstructure exhibiting substantially uniform pore size distribution throughout the porous support layer.
  • the present invention may also be characterized as a product by process wherein the product is a composite oxygen transport membrane.
  • the process comprises: (i) ; (ii) applying an intermediate porous layer or fuel oxidation layer on the porous support layer, (iii) applying a dense separation layer on the intermediate porous layer; and (iv) introducing catalyst particles or a solution containing precursors of the catalyst particles to the porous support layer and intermediate porous layer, the catalyst particles containing a catalyst selected to promote oxidation of a combustible substance in the presence of the separated oxygen transported through the dense layer and the intermediate porous layer to the porous support layer.
  • Both the intermediate porous layer and dense separation layer are capable of conducting oxygen ions and electrons to separate oxygen from an oxygen containing feed.
  • Both layers comprise a mixture of a fluorite structured ionic conductive material and electrically conductive materials to conduct the oxygen ions and electrons, respectively.
  • the pore forming enhancement process involves the use of bi- modal or multi-modal particle sizes of the polymethyl methacrylate based pore forming material and/or the fluorite structured ionic conducting material of the porous support layer.
  • the step of introducing catalyst particles or a solution containing precursors of the catalyst particles to the porous support layer and intermediate porous layer may further comprise either: (a) adding catalyst particles directly to the mixture of materials used in the intermediate porous layer; or (b) applying a solution containing catalyst precursors to the porous support layer on a side thereof opposite to the intermediate porous layer so that the solution infiltrates or impregnates the pores within the porous support layer and the intermediate porous layer with the solution containing catalyst precursors and heating the composite oxygen transport membrane after the solution containing catalyst precursors infiltrates the pores and to form the catalyst from the catalyst precursors.
  • Each of the dense layer and the intermediate porous layer are capable of conducting oxygen ions and electrons at an elevated operational temperature to separate oxygen from an oxygen containing feed.
  • the dense layer and the intermediate porous layer comprising mixtures of a fluorite structured ionic conductive material and electrically conductive materials to conduct oxygen ions and electrons, respectively.
  • the porous support layer comprises, and preferably consists essentially of, a fluorite structured ionic conducting material having a porosity of greater than about 20 percent and a microstructure exhibiting substantially uniform pore size distribution throughout the porous support layer. Pores are formed within the porous support layer using bi-modal or multi-modal particle sizes of the polymethyl methacrylate based pore forming material and/or using bi- modal or multi-modal particle sizes of the fluorite structured ionic conducting material of the porous support layer.
  • a pressure may be established on the second side of the porous support layer or the pores of the porous support layer and fuel oxidation layer may first be evacuated of air using a vacuum to further assist in wicking of the solution and prevent the opportunity of trapped air in the pores preventing wicking of the solution all the way through the support structure to the intermediate layer.
  • Fig. 1 is a cross-sectional schematic view of a composite oxygen transport membrane element of the present invention that is fabricated in accordance with a method of the present invention;
  • Fig. 2 is an alternative embodiment of Fig. 1;
  • FIG. 3 is an alternative embodiment of Fig. 1;
  • FIG. 4 is an SEM micrograph image at lOOOx magnification showing a porous support layer comprised of 3 YSZ with walnut shells as the pore forming material;
  • Fig. 5 is an SEM micrograph image at 2000x magnification showing a porous support layer comprised of 3YSZ with multi-modal particle sizes in accordance with the present invention.
  • FIG. 1 a sectional view of a composite oxygen transport membrane element 1 in accordance with the present invention is illustrated.
  • composite oxygen transport membrane element 1 could be in the form of a tube or a flat plate.
  • Such composite oxygen transport membrane element 1 would be one of a series of such elements situated within a device to heat a fluid such as in a boiler or other reactor having such a heating requirement.
  • Composite oxygen transport membrane element 1 is provided with a dense layer 10, a porous support layer 12 and an intermediate porous layer 14 located between the dense layer 10 and the porous support layer 12.
  • a preferable option is, as illustrated, to also include a porous surface exchange layer 16 in contact with the dense layer 10, opposite to the intermediate porous layer 14.
  • Catalyst particles 18 are located in the intermediate porous layer 14 that are formed of a catalyst selected to promote oxidation of a combustible substance in the presence of oxygen separated by the composite membrane element 1.
  • combustion substance means any substance that is capable of being oxidized, including, but not limited, to a fuel in case of a boiler, a hydrocarbon containing substance for purposes of oxidizing such substance for producing a hydrogen and carbon monoxide containing synthesis gas or the synthesis gas itself for purposes of supplying heat to, for example, a reformer.
  • oxidizing as used herein encompasses both partial and full oxidation of the substance.
  • air or other oxygen containing fluid is contacted on one side of the composite oxygen transport membrane element 1 and more specifically, against the porous surface exchange layer 16 in the direction of arrowhead "A".
  • the porous surface exchange layer 16 is porous and is capable of mixed conduction of oxygen ions and electrons and functions to ionize some of the oxygen.
  • the oxygen ions are transported through the dense layer 10 to intermediate porous layer 14 to be distributed to pores 20 of the porous support layer 12. It should be noted that in Figs.
  • the pores 20 within the porous support layer 12 are shown in an exaggerated manner.
  • Some of the oxygen ions, upon passage through the dense layer will recombine into elemental oxygen.
  • the recombination of the oxygen ions into elemental oxygen is accompanied by the loss of electrons that flow back through the dense layer to ionize the oxygen at the opposite surface thereof.
  • a combustible substance for example a hydrogen and carbon monoxide containing synthesis gas, is contacted on one side of the porous support layer 12 located opposite to the intermediate porous layer 14 as indicated by arrowhead "B".
  • the combustible substance enters pores 20, contacts the oxygen and burns through combustion supported by oxygen.
  • the combustion is promoted by the catalyst that is present by way of catalyst particles 18.
  • the presence of combustible fuel on the side of the composite oxygen ion transport membrane element 1, specifically the side of the dense layer 10 located adjacent to the intermediate porous layer 14 provides a lower partial pressure of oxygen.
  • This lower partial pressure drives the oxygen ion transport as discussed above and also generates heat to heat the dense layer 10, the intermediate porous layer 14 and the porous surface exchange layer 16 up to an operational temperature at which the oxygen ions will be conducted.
  • the incoming oxygen containing stream can also be pressurized to enhance the oxygen partial pressure difference between opposite sides of the composite oxygen ion transport membrane element 1. Excess heat that is generated by combustion of the combustible substance will be used in the specific application, for example, the heating of water into steam within a boiler or to meet the heating requirements for other endothermic reactions.
  • the use of a single phase mixed conducting material such as a perovskite structured materials has the disadvantage of exhibiting chemical expansion, or in other words, one side of a layer, at which the oxygen ions recombine into elemental oxygen, will expand relative to the opposite side thereof. This resulting stress can cause failure of such a layer or separation of the layer from adjacent layers.
  • the dense layer, the intermediate porous layer, and the porous surface exchange layer were all formed of a two phase system comprising a fluorite structured material in one phase as the ionic conductor of the oxygen ions and an electronic conducting phase that in the illustrated embodiment is a perovskite type material.
  • the porous support layer 12, 12', 12" have a thickness of between about 0.5 mm and about 4.0 mm, and more preferably about 1.0 mm and are preferably formed only of a fluorite structured material or of a fluorite structured material only with a PMMA based pore former material.
  • the porous support layers 12; 12' and 12" preferably do not exhibit significant mixed conduction.
  • the material used in forming the porous support layer preferably have a thermal expansion coefficient in the range 9 x 10 "6 cm/cm x K "1 and 12 x 10 "6 cm/cm x K "1 in the temperature range of 20°C to 1000°C; where "K” is the temperature in Kelvin.
  • dense layers 10, 10', 10" or dense separation layers function to separate oxygen from an oxygen containing feed exposed to one surface of the oxygen ion transport membrane 10 and contains an electronic and ionic conducting phases.
  • the dense separation layer also serves as a barrier of sorts to prevent mixing of the fuel on one side of the membrane with the air or oxygen containing feed stream on the other side of the membrane.
  • the variable " ⁇ " as used in the formulas set forth below for the indicated substances, as would be known in the art would have a value that would render such substances charge neutral. It is to be noted, that since the quantity (1-u-v) can be equal to zero, cerium may not be present within an electronic phase of the present invention.
  • the dense separation layer contains a mixture of 40 percent by weight (Lao.8Sr 0 .
  • the dense layer should be made as thin as possible and in the described embodiment has a thickness of between about 10 microns and about 50 microns.
  • Porous surface exchange layers 16, 16', 16" or air activation layers are designed to enhance the surface exchange rate by enhancing the surface area of the dense layers 10, 10', 10" while providing a path for the resulting oxygen ions to diffuse through the mixed conducting oxide phase to the dense layer and for oxygen molecules to diffuse through the open pore spaces to the same.
  • the porous surface exchange layer 16, 16', 16" therefore, reduces the loss of driving force in the surface exchange process and thereby increases the achievable oxygen flux.
  • porous surface exchange layer is formed of a mixture of about 50 percent by weight of (Lao.8Sr 0 . 2 )o. 8Mn03-6, remainder lOSclYSZ.
  • the porous surface exchange layer is a porous layer and preferably has a thickness of between about 10 microns and about 40 microns, a porosity of between about 30 percent and about 60 percent and an average pore diameter of between about 1 microns and about 4 microns.
  • the intermediate porous layer 14, 14', 14" is a fuel oxidation layer and is a preferably formed of the same mixture as the dense layer 10, 10', 10" and preferably has an applied thickness of between about 10 microns and about 40 microns, a porosity of between about 25 percent and about 40 percent and an average pore diameter of between about 0.5 microns and about 3 microns.
  • catalyst particles 18, 18', 18" are incorporated within the intermediate porous layer 14, 14', 14" that are catalyst particles 18, 18', 18".
  • the catalyst particles 18, 18', 18" in the described embodiments are preferably gadolinium doped ceria ("CGO") that have a size of between about 0.1 and about 1 microns.
  • the intermediate porous layers contain a mixture of about 60 percent by weight of (Lao.825Sr 0 .i75)o. 6Cr 0 .76Feo.225Vo.oi503-6, remainder lOSclYSZ.
  • intermediate porous layer as compared with the dense layer preferably may contain iron in lieu of or in place of manganese, a lower A-site deficiency, a lower transition metal (iron) content on the B-site, and a slightly lower concentration of vanadium on the B-site. It has been found that the presence of iron in the intermediate porous layer aids the combustion process and that the presence of manganese at higher concentration and a higher A-site deficiency in the dense layer improves electronic conductivity and sintering kinetics. If needed, a higher concentration of vanadium should be present in the dense layer because vanadium functions as a sintering aid, and is required to promote densification of the dense layer. Vanadium, if any, is required in lesser extent in the intermediate porous layer in order to match the shrinkage and thermal expansion characteristics with the dense layer.
  • the porous support layer 12, 12', 12" can be formed from a past mixture by known forming techniques including extrusion techniques and freeze casting techniques. Although pores 20, 20', 20" in the porous support layer are indicated as being a regular network of non-interconnected pores, in fact there exists some degree of connection between pores towards the intermediate porous layer. In any event, the porous network and microstructure of the porous support layer should be controlled so as to promote or optimize the diffusion of the combustible substance to the intermediate porous layer and the flow of combustion products such as steam and carbon dioxide from the pores in a direction opposite to that of arrowhead "B". The porosity of porous support layers 14, 14', 14" should preferably be greater than about 20 percent for the described embodiment as well as other possible embodiments of the present invention.
  • porous support layers 12, 12', 12" are possibly fabricated from 3YSZ material commercially available from various suppliers including Tosoh Corporation and its affiliates, including Tosoh USA, with an address at 3600 Gantz Road, Grove City, Ohio. Advancements in the performance of the porous support layers have been realized when using 3YSZ with multi-modal particle sizes. Optionally, it could be combined with fugitive organic pore former materials, specifically polymethyl methacrylate (PMMA).
  • PMMA polymethyl methacrylate
  • the pore forming material is preferably a mixture comprising 30wt% carbon black with an average particle size less than or equal to about 1 micron combined with 70wt% PMMA pore formers having a narrow particle size distribution and an average particle size of between about 0.8 microns and 5.0 microns.
  • PMMA pore formers with a narrow particle size distribution have shown promising results, further pore optimization and microstructure optimization may be realized using bi-modal or multi-modal particle size distributions of the PMMA based pore formers.
  • bi-modal or multimodal particle size distribution of PMMA pore formers including PMMA particles with average particle diameters of 0.8 microns, 1.5 microns 3.0 microns and 5.0 microns are contemplated.
  • the preferred fabrication process of the oxygen transport membrane is to form the porous support via an extrusion process and subsequently bisque firing of the extruded porous support.
  • the porous support is then coated with the active membrane layers, including the intermediate porous layer and the dense layer, after which the coated porous support assembly is dried and fired.
  • the coated porous support assembly is then co-sintered at a final optimized sintering temperature and conditions.
  • An important aspect or characteristic of the materials or combination of materials selected for the porous support is its ability to mitigate creep while providing enough strength to be used in the oxygen transport membrane applications, which can reach temperatures above 1000°C and very high loads. It is also important to select porous support materials that when sintered will demonstrate shrinkages that match or closely approximate the shrinkage of the other layers of the oxygen transport membrane, including the dense separation layer, and intermediate porous layer.
  • the final optimized sintering temperature and conditions are selected so as to match or closely approximate the shrinkage profiles of the porous support to the shrinkage profiles of the dense separation layer while minimizing any chemical interaction between the materials of the active membrane layers, the materials in the porous support layer, and the sintering atmosphere.
  • Too high of a final optimized sintering temperature tends to promote unwanted chemical interactions between the membrane materials, the porous support, and surrounding sintering atmosphere. Reducing atmospheres during sintering using blends of hydrogen and nitrogen gas atmosphere can be used to reduce unwanted chemical reactions but tend to be more costly techniques compared to sintering in air.
  • an advantage to the oxygen transport membrane of the disclosed embodiments is that some may be fully sintered in air.
  • a dense separation layer comprising (Lao.8Sr 0 .2)o. 5Cr 0 .5Feo.503-6 and lOSclCeSZ appears to sinters to full density in air at about 1400°C tol430°C.
  • Figs. 4 and 5 are SEM micrographs (respectively lOOOx magnification and 2000x magnification) which show greater pore uniformity and overall porous support layer microstructure uniformity when using a porous support comprised of fluorite structured ionic conducting material having bi-modal or multi-modal particle sizes (Fig. 5) than a porous support comprised of 3YSZ and walnut shell pore formers (Fig. 4).
  • Porous support microstructure shown in Fig. 5 exhibited higher strength, lower creep, and improved diffusion efficiency compared to a 3YSZ porous support having a single average particle size 3YSZ and larger size walnut shell pore formers (see Fig. 4).
  • porous support layers 12, 12', 12" preferably have a permeability of between about 0.25 Darcy and about 0.5 Darcy. Standard procedures for measuring the permeability of a substrate in terms of Darcy number are outlined in ISO 4022. Porous support layers 12, 12', 12" also preferably have a thickness of between about 0.5 mm and about 4 mm and an average pore size diameter of no greater than about 50 microns. Additionally, the porous support layers also have catalyst particles 18, 18', 18" located within pores 20, 20', 20" and preferably adjacent to the intermediate porous layer for purposes of also promoting combustible substance oxidation.
  • catalyst particles both within the intermediate porous layer and within the porous support layer provides enhancement of oxygen flux and therefore generation of more heat via combustion that can be obtained by either providing catalyst particles within solely the intermediate porous layer or the porous support layer alone. It is to be noted that to a lesser extent, catalyst particles can also be located in region of the pores that are more remote from the intermediate porous layer, and therefore do not participate in promoting fuel oxidation. However, the bulk of catalyst in a composite oxygen transport element of the present invention is, however, preferably located in the intermediate porous layer and within the pores adjacent or proximate to the intermediate porous layer.
  • the porous support 12, 12', 12" is first formed in a manner known in the art and as set forth in the references discussed above.
  • standard ceramic extrusion techniques can be employed to produce a porous support layer or structure in a tube configuration in a green state and then subjected to a bisque firing at 1050°C for about 4 hours to achieve reasonable strength for further handling.
  • bisque firing the resulting tube can be checked or tested for targeted porosity, strength, creep resistance and, most importantly, diffusivity characteristics.
  • a freeze cast supporting structure could be formed as discussed in "Freeze-Casting of Porous Ceramics: A Review of Current Achievements and Issues” (2008) by Deville, pp. 155-169. (00045)
  • intermediate porous layer 14, 14', 14" is then formed.
  • a mixture of about 34 grams of powders having electronic and ionic phases, LSCMV and lOSclYSZ, respectively, is prepared so that the mixture contains generally equal proportions by volume of LSCMV and lOSclYSZ.
  • the catalyst particles such as CGO, are so incorporated into the electronic phase LSCMV by forming deposits of such particles on the electronic phase, for example, by precipitation.
  • the catalyst particles within the intermediate porous layer by wicking a solution containing catalyst precursors through the porous support layer towards the intermediate porous layer after application of the membrane active layers as described in more detail below.
  • the electronic phase particles are each about 0.3 microns prior to firing and the catalyst particles are about 0.1 microns or less and are present in a ratio by weight of about 10wt%.
  • 100 grams of toluene, 20 grams of the binder of the type mentioned above, 400 grams of 1.5 mm diameter YSZ grinding media are added. The mixture is then milled for about 6 hours to form a slurry (d 5 o of about 0.34 ⁇ ).
  • a mixture weighing about 40 grams is prepared that contains the same powders as used in forming the intermediate porous layer, discussed above, except that the ratio between LSCMV and lOSclYSZ is about 40/60 by volume, 2.4 grams of cobalt nitrate ⁇ Co(N03) 2 .6H 2 0 ⁇ , 95 grams of toluene, 5 grams of ethanol, 20 grams of the binder identified above, 400 grams of 1.5 mm diameter YSZ grinding media are then added to the mixture and the same is milled for about 10 hours to form a slurry (d 5 o ⁇ 0.34 ⁇ ). Again, about 10 grams of toluene and about 10 grams of binder are added to the slurry and mixed for about 1.5 and about 2 hours. The inner wall of the tube is then coated by pouring the slurry, holding once for about 10 seconds and pouring out the residual back to the bottle. The coated green tube is then stored dry prior to firing the layers in a controlled environment.
  • the coated green tube is then placed on a C-setter in a horizontal tube furnace and porous alumina tubes impregnated with chromium nitrate are placed close to the coated tube to saturate the environment with chromium vapor.
  • the tubes are heated in static air to about 800°C for binder burnout and, if necessary, the sintering environment is switched to an atmosphere of a saturated nitrogen mixture (nitrogen and water vapor) that contains about 4 percent by volume of hydrogen to allow the vanadium containing electronic conducting perovskite structured materials to properly sinter.
  • the tube is held at about 1350°C to 1430°C for about 8 hours and then cooled in nitrogen to complete the sintering of the materials.
  • the sintered tube is then checked for leaks wherein the helium leak rates should be lower than 10 "7 Pa.
  • a mixture of powders is prepared that contains about 35g of equal amounts of ionic and electronic phases having chemical formulas of Zr 0 .8oSco.i8Yo.o 2 0 2 _6 and La 0 .8Sr 0 . 2 FeO3-6, respectively.
  • To this mixture about 100 grams of toluene, 20 grams of the binder identified above, about 400 grams of 1.5 mm diameter YSZ grinding media are added and the resultant mixture is milled for about 14 hours to form a slurry (d 5 o ⁇ 0.4 ⁇ ). About six grams of carbon black are added to the slurry and milled for additional 2 hours.
  • a mixture of about 10 grams of toluene and about 10 grams of the binder are then added to the slurry and mixed for between about 1.5 and about 2 hours.
  • the inner wall of the tube is then coated by pouring the slurry, holding twice for about 10 seconds and then pouring out the residual back to the bottle.
  • the coated tube is then dried and fired at 1100°C for two hours in air.
  • the structure formed in the manner described above is in a fully sintered state and the catalyst is then further applied by wicking a solution containing catalyst precursors in the direction of arrowhead B at the side of the porous support opposite to the intermediate porous layer.
  • the solution can be an aqueous metal ion solution containing about 20 mol% Gd(N0 3 ) 3 and 80 mol% Ce(N0 3 ) 3 .
  • a pressure can be established on the side of the porous support layer to assist in the infiltration of the solution.
  • the pores can first be evacuated of air using a vacuum to further assist in wicking of the solution and prevent the opportunity of trapped air in the pores preventing wicking of the solution all the way through the porous support layer to the intermediate porous layer.
  • the resulting composite oxygen transport membrane 1 in such state can be directly placed into service or further fired prior to being placed into service so that the catalyst particles, in this case Ceo.sGdo.202-6 are formed in the porous support layer adjacent to the intermediate porous layer and as described above, within the intermediate porous layer itself.
  • the firing to form Ceo.sGdo.202-6 would take place at a temperature of about 850°C and would take about 1 hour to form the catalyst particles.

Abstract

L'invention concerne une couche de support poreuse pour une membrane composite de transport d'oxygène, ledit support étant composé d'un matériau conducteur ionique structuré en fluorine avec une porosité supérieure à 20 % et une microstructure présentant une distribution de taille de pores pratiquement uniforme sur toute la couche de support poreuse, la couche de support poreuse étant formée à partir d'un mélange comprenant un matériau conducteur ionique structuré en fluorine ou à partir d'un mélange comprenant un matériau de formation de pores à base de polyméthyl-méthacrylate et un matériau conducteur ionique structuré en fluorine, ledit matériau de formation de pores à base de polyméthyl-méthacrylate et/ou ledit matériau conducteur ionique structuré en fluorine ayant des granulométries bimodales ou multimodales.
EP13792299.3A 2012-11-08 2013-11-08 Couche de support poreuse Withdrawn EP2916934A1 (fr)

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US13/671,835 US20130072374A1 (en) 2010-12-15 2012-11-08 Catalyst containing oxygen transport membrane
US13/672,975 US9561476B2 (en) 2010-12-15 2012-11-09 Catalyst containing oxygen transport membrane
PCT/EP2013/073413 WO2014072474A1 (fr) 2012-11-08 2013-11-08 Couche de support poreuse

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US10183457B2 (en) 2013-05-16 2019-01-22 Korsch Ag System and method for exchanging vertically segmented rotor segments on a rotary tablet press
US10441922B2 (en) 2015-06-29 2019-10-15 Praxair Technology, Inc. Dual function composite oxygen transport membrane
EP3797085A1 (fr) 2018-05-21 2021-03-31 Praxair Technology, Inc. Panneau de gaz de synthèse otm avec reformeur chauffé au gaz
JP7285117B2 (ja) * 2019-03-29 2023-06-01 株式会社ノリタケカンパニーリミテド 固体酸化物形燃料電池の支持体形成用材料およびその利用
CN113394415B (zh) * 2021-06-17 2024-04-16 广西师范大学 一种富氧空位NC@BiOCl-CNTs复合材料及其制备方法和应用

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US7125528B2 (en) * 2002-05-24 2006-10-24 Bp Corporation North America Inc. Membrane systems containing an oxygen transport membrane and catalyst
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US8323463B2 (en) * 2010-01-22 2012-12-04 Praxair Technology, Inc. Catalyst containing oxygen transport membrane
US20130072374A1 (en) * 2010-12-15 2013-03-21 Jonathan A. Lane Catalyst containing oxygen transport membrane
US9561476B2 (en) * 2010-12-15 2017-02-07 Praxair Technology, Inc. Catalyst containing oxygen transport membrane

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