+

WO2006066973A2 - Procede de fabrication d'un cermet de nickel pour des cellules electrochimiques a oxydes solides - Google Patents

Procede de fabrication d'un cermet de nickel pour des cellules electrochimiques a oxydes solides Download PDF

Info

Publication number
WO2006066973A2
WO2006066973A2 PCT/EP2005/014180 EP2005014180W WO2006066973A2 WO 2006066973 A2 WO2006066973 A2 WO 2006066973A2 EP 2005014180 W EP2005014180 W EP 2005014180W WO 2006066973 A2 WO2006066973 A2 WO 2006066973A2
Authority
WO
WIPO (PCT)
Prior art keywords
previous
nickel
oxide
metallic
layer
Prior art date
Application number
PCT/EP2005/014180
Other languages
English (en)
Other versions
WO2006066973A3 (fr
Inventor
Francesco Pittalis
Federico Capuano
Luigina Maria Flora Sabatino
Original Assignee
Eni S.P.A.
Enitecnologie S.P.A.
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
Application filed by Eni S.P.A., Enitecnologie S.P.A. filed Critical Eni S.P.A.
Publication of WO2006066973A2 publication Critical patent/WO2006066973A2/fr
Publication of WO2006066973A3 publication Critical patent/WO2006066973A3/fr

Links

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/88—Processes of manufacture
    • H01M4/8878—Treatment steps after deposition of the catalytic active composition or after shaping of the electrode being free-standing body
    • H01M4/8882—Heat treatment, e.g. drying, baking
    • H01M4/8885—Sintering or firing
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/10—Alloys containing non-metals
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/10—Alloys containing non-metals
    • C22C1/1089—Alloys containing non-metals by partial reduction or decomposition of a solid metal compound
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/8605—Porous electrodes
    • H01M4/8621—Porous electrodes containing only metallic or ceramic material, e.g. made by sintering or sputtering
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M4/90—Selection of catalytic material
    • H01M4/9041—Metals or alloys
    • H01M4/905—Metals or alloys specially used in fuel cell operating at high temperature, e.g. SOFC
    • H01M4/9066—Metals or alloys specially used in fuel cell operating at high temperature, e.g. SOFC of metal-ceramic composites or mixtures, e.g. cermets
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M4/00—Electrodes
    • H01M4/86—Inert electrodes with catalytic activity, e.g. for fuel cells
    • H01M2004/8678—Inert electrodes with catalytic activity, e.g. for fuel cells characterised by the polarity
    • H01M2004/8684—Negative electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M8/00—Fuel cells; Manufacture thereof
    • H01M8/10—Fuel cells with solid electrolytes
    • H01M8/12—Fuel cells with solid electrolytes operating at high temperature, e.g. with stabilised ZrO2 electrolyte
    • H01M2008/1293—Fuel cells with solid oxide electrolytes
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/30—Hydrogen technology
    • Y02E60/50—Fuel cells

Definitions

  • the present invention relates to a method for the preparation of a nickel cermet which can be used in the manufacturing of solid oxide fuel cells (SOFC) . More specifically, the present invention relates to a method for the preparation of a sinterable composition comprising metallic nickel in close contact with certain ceramic materials , capable of promoting anodic reactions in a fuel cell .
  • SOFC solid oxide fuel cells
  • Solid oxide fuel cells comprising a solid electrolyte consisting of a mixture of yttrium oxide (yttria) (Y 2 O 3 ) and zirconium oxide (zirconia) (ZrO 2 ) , an anode made up of a nickel/zirconium oxide cermet and a cathode of lanthanum manganite (LaMnO 3 ) , are known in the art .
  • This sub- j ect is generally dealt with, for example , in the publication "Ullmann' s Encyclopedia of Industrial Chemistry, Vol .
  • the nickel/zirconium oxide cermet used as anodic material normally consists of a dispersion of metallic nickel in zirconium oxide stabilized in cubic crystalline form with from 5 to 20% by weight of yttrium oxide .
  • the processes for the preparation of said cermet essentially comprise the mechanical dispersion of nickel oxide in stabilized zirconium oxide , followed by the reduction of the nickel oxide to metallic nickel , usually during the anodic activation process with gaseous hydrogen at high temperatures .
  • the nickel cermets obtained by means of the processes of the known art do not obtain completely satisfactory per- formances and do not have the necessary flexibility for providing an optimum response to the various demands arising in their application in fuel cells .
  • the traditional preparation techniques of nickel-based cermets are not particularly flexible when other elements are to be introduced together with the nickel , which are capable of conferring to the anode , in reduced form, in the metallic state , or in oxide form with particular dispersions and morphology, other properties , such as, for example, a greater dimensional stability and mechanical resistance , promotion of the dispersion and reactive efficiency of the nickel towards the anodic gas , the capacity of activating the reforming of natural gas , resistance to micro-pollutants in food, and others .
  • this has been achieved, for example, by mixing and sintering different types of oxides and reducing the solid thus obtained . In this way, however, a satisfactory homogeneity of the product is not obtained and the expected improvements are often not observed.
  • a first obj ect of the present invention therefore relates to a method for the production of a ceramic-metallic composition (cermet) consisting of at least 70% , preferably at least 85% , by weight of a solid material comprising, in a mixture , from 35 to 70% by weight of a metallic nickel phase and from 65 to 30% by weight of at least one oxide selected from oxides of transition metals and lanthanides , comprising the following steps in succession : i) preparing a mixture of powders substantially free of nickel oxide , comprising metallic nickel and at least one oxide different from nickel oxide , selected from the oxides of transition metals and lanthanides ; ii) laying said mixture of powders on a suitable surface , in the form of a layer having a thickness ranging from 2 to
  • powder refers to a particulate having a particle-size which is such that at least 90% by weight of the particles have a diameter ranging from 0.5 to 500 ⁇ m.
  • the nickel cermet obtained with the method of the present invention, consists of 35 to 70% by weight of a metallic nickel phase and from 65 to 30% by weight of a zirconium oxide ( zirconia) phase , stabilized in cubic form by 3 to 15 moles , more preferably from 5 to 10 moles , of yttrium oxide (yttria) for every 100 moles of zirconium oxide, the two phases , upon X-ray dif- fractometry, being distinct and homogeneously distributed .
  • a mixture of metallic nickel in powder form is prepared with at least one oxide of a transition metal or of the group of lanthanides .
  • the nickel and oxide (of a different transition metal) powders are mixed with each other as homogeneously as possible , in such quantities as to respect the desired proportions in the final cermet .
  • the metallic nickel in powder form preferably has a particle-size which is such that d 50 (mesh width of the sieve which allows the passage of 50% by weight of the pow ⁇
  • powders with a bi- or poly-modal distribution, or having a filamentous structure (microfibres) or mixtures of said powders can also be used in accordance with said step (i) .
  • These powders can be obtained by the grinding of metallic nickel in an inert atmosphere , by means of processes and equipment well known in the art .
  • Nickel powders with the above particle-sizes are also commercially available , for
  • Suitable metal oxides for the formation of the mixture of powders according to step ( i) are porous oxides or mixtures of oxides having the function of an electrolyte under the functioning conditions of an SOFC .
  • Said lanthanide oxides or oxides of transition metals exert , in the final form of the cermet , a supporting and ion transporting func- tion, making the anode more stable with time and allowing the maximum dispersion of the nickel to increase the contact with the reducing gas (usually hydrogen) .
  • Oxides suitable for this purpose have been developed for some time and are widely described in technical literature in the field.
  • Typical , non-limiting examples are oxides of Bi , Sr, Zr, Y, Ce , Ga, Sc , Mn, La, Ca, Pr, Yb, Nd, Sm and mixtures thereof .
  • excellent results can be obtained mixed oxides of Zr and Y ( zirconia-yttrium) , especially in an atomic ratio of 92/8 (commercial product also called 8YSZ) , Ce and Ga (cerium-gadolinia) , Zr and Ca (zirconia- calcia) , and in general oxides and mixed oxides known in the specific field as SOFC electrolytes .
  • the above powders of oxides preferably have an average
  • the preparation of the mixture of powders according to step (i ) can be effected according to any of the known methods suitable for the purpose .
  • the most common method is simple mixing of the preformed powders in a suitable container .
  • the co-grinding is effected, according to the art , in suitable mortars , j ars , or other closed containers , with the help of steel balls and a suit- able vibrating device .
  • a further technique consists of co- grinding the components with rougher shapes and dimensions , in suitable mills , to obtain a powder having the desired particle-size .
  • Step (ii ) of the method according to the present in- vention consists in the preparation, with any suitable apparatus and method, of a layer of the mixture obtained in step (i) having the desired thickness .
  • This layer can be laid on a suitable carrier which can advantageously also consist of a layer of a suitable SOFC electrolyte , normally
  • the conformation of the layer obtained according to step (ii) is not critical but can vary according to the circumstances and final use of the cermet produced .
  • Exam- pies of geometries suitable for use in fuel cells having different forms are , for example , simple flat geometry, obtained for example with tape casting technologies , or a cylindrical geometry, produced for example by the slurry coating of a suspension in an aqueous solution of methyl cellulose .
  • step (ii) One of the known techniques which is most suitable for the purpose is screen printing, adapted to the circumstances of the specific case .
  • suitable organic components are nor- mally added to the mixture of powders obtained in step (i) , suitable for forming a paste having the desired viscosity and consistence , with thixotropic properties .
  • Components of this kind are waxes or organic oils , either liquid or with a creamy consistency at room temperature , or solutions of cellulose derivatives , which undergo decomposition and oxidation in the subsequent phase (iii) of the present method without substantially leaving traces or residues in the cermet obtained at the end .
  • a thickness ranging from 50 to 1500 ⁇ m, and preferably from 200 to 1000 ⁇ m for supporting anodes and from 50 to 300 ⁇ m for supported anodes .
  • said anodic layer is not obtained separately from the other essential layers of the cell , but is shaped into the desired form, with at least one surface in contact with an electrolyte layer or with a precursor thereof , for example a serigraphic paste of the type mentioned above .
  • the electrolyte is selected from any of the materials suitable for the purpose, preferably one of the above oxides or mixtures of oxides of a transition metal or lanthanide , more preferably the same electrolyte oxide used in a mixture with the nickel powder of step (i) .
  • the precursor lay- ers thus assembled are then subj ected to treatment according to the subsequent step (iii) .
  • the heating under oxidizing conditions in step (iii) of the layer of powders obtained in step (ii) is carried out at a temperature and for a duration which are suffi- cient for obtaining the desired sintering degree of the cermet (or whole cell element if already prepared together with the cermet forming the anode) , to form a solid having the desired consistency consisting of particles of oxide , preferably YSZ , with high temperature ion conductor charac- teristics , covered with nickel oxide .
  • the heating conditions are preferably selected from those normally used in obtaining SOFC anodic layers .
  • suitable sintering temperatures generally range from 900 to 1600 0 C, more preferably from 1100 to 1500 0 C, and the times can vary from a few minutes to several hours .
  • zirconia-based oxides it is preferable to operate at temperatures in the order of 1100 - 1300 0 C for a time ranging from 30 minutes to 4 hours .
  • the oxidizing environment can consist of oxygen, air or oxygen-enriched air .
  • the oxides of the metals present Ni and possible additional metals , for example Cu, Cr, Co, Rh, Ru, Al
  • Ni and possible additional metals for example Cu, Cr, Co, Rh, Ru, Al
  • a nickel oxide or a mixture of this oxide with other possible oxides of said addi- tional metals is obtained, which proves to be surprisingly effective both in the normal use of the cermet as anode in a SOFC, and also in the catalysis of the contemporaneous reforming in the case of feeding with hydrocarbons .
  • Even if this does not refer to any particular theory or model it is felt that the best performances of the cermet , according to the present invention, can be attributed to an unusual arrangement and morphology of the additional metal on the nickel particle .
  • Said step (iii) is preferably preceded by an optional pre-sintering process at a temperature close to the sintering value, at which said mixtures of powders are transformed into an aggregate material which is such that it does not release powders into the environment .
  • This aggregation process is different and precedes the sintering pro- cess in which, with the possible help of high pressures , micro-fusions are formed on the surface of the granules .
  • said temperature close to the sintering value is conveniently selected from 50 to 300 0 C lower than the minimum temperature at which a certain mixture of powders , under the pre-selected pressure conditions , begins to sinter .
  • said temperature is normally higher than 800 0 C, preferably ranging from 1000 to 1300 0 C .
  • all the metallic nickel present in the mixture of powders is essentially transformed into oxide during said step (iii) , so that at the end, the content of metallic nickel possibly remaining in the sintered layer is lower than 0.5% by weight , preferably lower than 0.1% by weight .
  • step (iii) the layer of powders is subj ected to progressive heating following a pre- established profile , until the effective pre-sintering and/or sintering temperature is reached, in order to avoid the arising of defects or distortions due to a sudden heating up to temperatures in the order of 1000 0 C .
  • the porous solid (or sintered) layer, obtained at the end of said step (iii) is normally subj ected to a further optional treatment (iv) with hydrogen, to reduce the nickel oxide to metallic nickel and thus obtain the desired product ready for use in an SOFC .
  • Said step (iv) is preferably carried out after installation of the sintered layer in the anodic structure of a fuel cell , as an activation step by the passage of hydrogen at a high temperature .
  • the reduction is carried out by putting the solid in contact with hydrogen or with a gas containing hydrogen, for example H 2 /Ar mixtures , operating at tempera- tures ranging from 600 to 1000 0 C and H 2 pressures ranging from 50 to 500 Kpa, in order to obtain the complete or substantially complete reduction of the nickel oxide (NiO) to metallic Ni .
  • a gas containing hydrogen for example H 2 /Ar mixtures
  • any other possible reducible oxides such as , for example , CuO or CoO, present in the solid layer are transformed into the corresponding metal in close contact with the nickel , obtaining an improved efficacy in the subsequent uses as a multifunctional cell anode .
  • Convenient reduction times are in the order of 5 to 48 hours , preferably from 10 to 30 hours , depending on the thickness of the anodic layer .
  • the reduction mixture has a hydrogen content which increases with time until reaching the pre-established partial pressure value .
  • the ceramic-metallic composition (nickel cermet) thus obtained has a porous structure with a porosity (pore vol ume/apparent volume of the solid, measured by means of a mercury porosimeter) ranging from 30 to 80% , preferably from 30 to 50% for thin anodes and from 40 to 70% for sup- ported anodes , in which the surface portion of the oxide covered by nickel generally ranges from 4 to 30% or even more) .
  • nickel oxide powders are not used as starting material and neither are these powders produced or made accessible to operators during any of the steps of the embodiment of the method, as the nickel oxide produced under the oxidative conditions of step (iii) is already in a stratified and structurally stable conformation which does not produce any powder dispersion in the surrounding environment .
  • the present method thus proves to be significantly advantageous and enhanced with respect to the known art , also in terms of a lower impact relating to health and environment .
  • Said metal M added in metallic form or as an oxide different from that forming the electrolytic oxide , gives the cermet additional catalytic activities and is distributed, when metal fine powder is used as starting material , with an advantageous conformation with respect to the nickel particles , i . e . irregularly arranged in microlayers on said particles .
  • the metal M is particularly selected from transition metals with a redox or hydrogenating capacity, such as Cu, Co , Fe , Rh, Ru, Pt and Pd .
  • the nickel in powder form can be premixed (for example by co-grinding) with the metal M, preferably in the form of a metallic powder, for example Ni and Al , Ni and Cu, Ni and Rh, Ni and Co, Ni and Ru, before carrying out step (i) of the claimed process .
  • a metallic powder for example Ni and Al , Ni and Cu, Ni and Rh, Ni and Co, Ni and Ru
  • Nickel is in fact suitable for the preparation of alloys with numerous metals , also by mechanical alloying (for example by co-grinding in a friction mill ) which does not require mixing of the two metals in the molten state and subsequent grinding, but allows , in the metallic precursor phase, in step (i) , mixtures of metals to be introduced in a heterogeneous particulate , but in close contact with each other, capable of producing, in the final cermet , morphologies which cannot be obtained with the usual metallic alloys . Furthermore , it is thus possible to closely combine metals which are not miscible with each other in alloys .
  • alloyed nickel powders with suitable promoters could therefore lead the way to the production of SOFC anodes capable of providing higher performances than those of the traditional anodes . It is thus possible to obtain composite (alloyed) metallic powders based on nickel and one or more other metals capable of exerting coadjuvant functions during the use of the cermet .
  • the quantity of metal M added to the mixture of step (i) is selected on the basis of the desired application .
  • Suitable amounts of metal M may be ranging in a quantity from 1 to 80% , preferably from 2 to 40% , even more prefera- bly from 2 to 15%, by weight with respect to the nickel .
  • Said further metal M can also be added according to the tape-casting technique, in which the metal M, the nickel in powder form and the electrolyte oxide (for example YSZ) are suspended in an aqueous solution of methyl cellulose to obtain a paste, which is then laid in a layer having the desired shape and thickness and subsequently calcined and sintered according to step (iii) .
  • Said tape-casting technique is , more generally, among those which can be used for obtaining compositions accord- ing to the present invention, in a planar form suitable for the production of cells with supporting anodes (normally called anode-supported SOFC) , in which the thickness of the
  • anodic layer preferably ranges from 200 to 1000 ⁇ m, more preferably from 400 to 800 ⁇ m, whereas the electrolyte layer is much thinner than that of the traditional SOFC,
  • the anode of these cells is structured in a supporting layer of the type specified above and a further
  • the method according to the present invention advantageously allows said cells with a supporting anode to be obtained, with lesser risks of causing fractures of the planar layers , as a result of tensions caused by the different shrinkage coefficient of the materials during the sintering step .
  • the present method however also comprises the introduction, in step (i) or also in the preparation of the composition of step (ii) , of the additional metal M in a dif- ferent form from the metallic state , for example in the form of an oxide (for example CuO, CoO, Cr 2 O 3 ) , or a suitable salt (thermally decomposable , for example nitrate) by means of impregnation .
  • a suitable salt thermalally decomposable , for example nitrate
  • multi-metallic cermets are obtained, after reduction according to step (iv) , which form a further obj ect of the present invention, and are characterized by a particular arrangement of the additional metal , which is stratified on the surface of the nickel granules , in areas or patches having a fine thickness and high surface , whereas the structure observed when the known procedures are used, starting from oxides , consists of micro-granules of said metal adj acent to or dispersed on the nickel granule .
  • a particular embodiment of the present invention relates to the preparation of such cermets of Ni containing additional metals M suitable for the contemporaneous steam or dry reforming of light hydrocarbons on a SOFC anode .
  • such metals like Pt , Ir and Cu can advantageously be added to nickel in the SOFC anode in order to carry out the steam reforming reaction of hydrocarbons , thus producing hydrogen ready for the anodic oxydation reaction, according to the following, non- limiting scheme : C n H 2n+2 + n H 2 O *, ( 2n + 1 ) H 2 + n CO
  • the method of the present invention allows the preparation of excellent compositions of Ni and additional cop- per, not only because no nickel oxide powder is used, but also because , in the preferred case of alligation of the two metals in step (i) , it produces a very good dispersion of copper on the surface of the nickel granules .
  • the metal Cu is preferably added to Ni in a quantity ranging from 2 to 20% , preferably from 5 to 10% , by weight with respect to the Ni .
  • a SOFC operated in such a way as to have also steam reforming reaction in its anodic portion is usually fed with a gaseous stream containing hydrocarbons , particularly natural gas or other mixture of methane with up to 30% by volume of higher hydrocarbons from ethane to hexane, and steam, in an amount at least sufficient to complete the foregoing reactions .
  • steam is used in a volume ratio from l/l to 4/1 with respect to the hydrocarbons .
  • Optimum operating conditions and details relating to SOFC anodic process including hydrocarbon reforming are well known in the art and available in a large number of publications and treaties .
  • An even further aspect of the present invention relates to the use of the nickel cermet described above as an anodic material (with the possibility of reforming) for solid oxide fuel cells (SOFC) .
  • this type of anode can be obtained by depositing , according to step (ii) above , for example by means of the techniques described, screen printing, plasma spraying, the nickel cermet of the present invention on a solid element consisting of an electrolyte of zirconium oxide stabilized with yttrium oxide , or another suitable electrolyte according to the known art , like ceria stabilized with gadolinia .
  • step (iv) for the reduction of the nickel oxide to metallic nickel can take place "in situ" , after the preparation of the cell structure : anode/electrolyte/cathode , and option- ally its positioning in the stack .
  • These solid oxide fuel cell comprising an anode made with the ceramic metallic composition of the present invention are conveniently used in a process for producing electric power .
  • the Applicant has further found that an improvement is achieved, in terms of efficiency, start-up and durability of power production, when the anode of said SOFC cell comprises a bimetallic composition of nickel and a redox metal like Cu, Pt , Rh, Ir, Pd, particularly in the presence of a contemporaneous steam-reforming reaction in the anodic section of the cell , wherein a gas mixture of steam and a hydrocarbon is fed to .
  • Typical fed hydrocarbon is selected from methane , natural gas and a mixture of methane and light hydrocarbons
  • the following examples are provided for a further illustration of the invention but should in no way be considered as limiting the scope of the invention itself .
  • Examples Example 1 Preparation of an anodic layer for SOFC cells starting from metallic Ni and YSZ .
  • a mixture is prepared, consisting of 42 g (35% by weight) of Zirconia ceramic material stabilized with Yttria
  • the particle-size of the ceramic powder is such that at least 95% of the granules has dimensions within the range of 5 to 10 microns ; the particle-size of the nickel powder ranges from 1 to 2 microns .
  • the mixture is put in a 250 ml zirconia j ar and is suspended in 100 ml of deionized water . 7 zirconia balls having a diameter of 2 cm are added to the j ar, and grinding is effected in a vibration mill for 24 hours .
  • the water is evaporated by means of a Iy- ophilization process and about 120 g of a homogeneously distributed solid mixture is obtained .
  • the carrier consists of a solution
  • ethyl cellulose (14% by weight) in ⁇ -terpineol , having a viscosity of 45 mPa .
  • the mixture is kept under stirring for 48 hours in order to make it homogeneous and passed over a zirconia roll paste mixer to finely disperse the powder granules .
  • the serigraphic ink thus obtained is deposited by screen printing on an electrolytic membrane consisting of
  • YSZ KERAFOL® product
  • the serigraphic halftone screen used is 250 mesh made of steel .
  • the electrolytic membrane with the anodic layer (semi- cell ) is left for 15 minutes at room temperature to allow a leveling of the layer itself , and is then put in an oven at
  • the cathodic layer consists of a layer of LSM (lanthanum manganite and strontium, Nextech product) . Preparation of the semi-sintered product .
  • LSM lanthanum manganite and strontium, Nextech product
  • the complete cell is put into an oven for the co-sintering in air of the electrodes .
  • the anodic layer after the sintering cycle in air consists of YSZ and NiO with a porosity ranging from 30% to 40% .
  • the nickel oxide is then reduced to metallic nickel using a reducing gas (hydrogen) directly in the housing of the SOFC cell (cell-holder) during the electric characterization phase .
  • a reducing gas hydrogen
  • the cell-holder consists of two ceramic shells between which the cell is inserted .
  • a nickel net (which acts as anodic current collector) is applied on the lower shell
  • anodic section (anodic section) and subsequently the SOFC cell .
  • a gold washer situated between the shell and cell , prevents the discharge of hydrogen from the anodic section .
  • the cell -holder is inserted in the oven where reduction is effected .
  • a stream containing Ar is initially sent , and its hydrogen content is gradually increased until it completely replaces the Ar over a period of 3 hours .
  • the temperature is brought to 800 0 C and hydrogen is maintained for a further 3 hours .
  • the oven is then cooled and the Ar content is increased again in the gas stream until the substantial elimination of the hydrogen.
  • the cell was subj ected to electric characterization .
  • the operating conditions were as follows :
  • Anodic gas hydrogen, 0.5 litres/minute
  • the determination of the voltage/current curve was effected by increasing the density of the current supplied by the cell and monitoring the voltage .
  • the same measurement was effected on a traditional-type cell , obtained with the same procedure described above , but using an equivalent quantity of NiO in powder form in the place of metallic Ni in the first step .
  • the results summarized in Table 2 below were obtained .
  • the measurement indicates that , with the same operat- ing conditions , the performances for both types of cell are substantially equivalent within the experimental accuracy range .
  • Example 2 preparation of an anodic layer (cermet) for SOFC cells starting from metallic nickel and Ceria stabilized with Gadolinia (CGO) . Preparation of the mixture of powders
  • a mixture is prepared, consisting of 50 g of Ceria ceramic material stabilized with Gadolinia (CGO, 40% by weight , Rhodia product) and 72 g of metallic nickel ( 60% by weight , INCO 255 product) , both in powder form.
  • the particle-size of the ceramic powder is such that at least 95% of the granules has dimensions within the
  • the particle-size of the nickel powder equally ranges from 1 to 2 ⁇ m.
  • the mixture is put in a 250 ml zirconia j ar and is suspended in 100 ml of deionized water .
  • 7 zirconia balls having a diameter of 2 cm are added to the j ar and grinding is effected for 24 hours in a vibration mill .
  • the water is evaporated by means of a Iy- ophilization process and about 121 g of a homogeneously distributed solid mixture are obtained.
  • the ceramic-metallic materials (or their precursors) prepared according to the previous Examples 1 and 2 were evaluated in methane steam-reforming tests under the normal operating conditions of an SOFC cell .
  • the approximately 500 mg sample of each material reduced to granular particulate (average dimension about 0.3 mm) was introduced into a quartz tubular reactor with a diameter of 13 mm, compressed between two double-layers , about 40 mm thick, of inert porous material , each composed of a layer of guarz grains and a layer of fiberglass . It was then reduced with hydrogen, operating at 600 0 C, with an analogous procedure to that described in Example 1 above . All traces of hydrogen are eliminated by passing helium until the dis- appearance of the characteristic chromatographic signal .
  • the method of the present invention therefore allow ceramic-metallic compositions to be obtained, under safer conditions and with a lower environmental impact , having electric and catalytic properties suitable for use in the preparation of SOFC, essentially similar to those of the analogous materials obtained from NiO powders .
  • Example 4 Ni-Cu bimetallic anodic composition
  • a ceramic-metallic composition comprising nickel and copper was prepared with a method analogous to that described in Example 1.
  • the ceramic-metallic material prepared according to the previous Example 4 , was evaluated in methane steam- reforming test by using the same laboratory reactor as de- cribed in previous example 3. Approximately 500 mg of each material , scraped from the anodic layer, were pressed to a tablet and then reduced to granular particulate by grinding (average dimension about 0.3 mm) . The sample so obtained was introduced into the tubular reactor . It was then reduced with hydrogen, operating at 600 0 C, with an analogous procedure to that described in Example 1 above . All traces of hydrogen are eliminated by passing helium until the disappearance of the characteristic chromatographic signal .
  • a mixture consisting of steam and a hydrocarbon composition containing, by volume, 87% methane , 10% ethane and 3% propane , with a ratio H 2 ⁇ /C ( to t) 2.0 , was fed to the re- actor at a WHSV space velocity of 2.1 h "1 .
  • the reaction products leaving the tubular reactor are analyzed by means of gaschromatography.
  • the temperature of the reactor is maintained at 800 0 C .
  • An initial carbon conversion of 70% was observed, which turned to about 80% after 200 hours running and remained stable to such value up to 500 hours , when the experiment was interrupted .
  • the carbon balance between the feed and product streams has shown that essentially no solid carbon remained in the reactor .
  • the cermet composition obtained from the alloyed metals containing only 5% of copper, has shown essentially no induction time at the start time of the experiment , and no deactivation or solid carbon deposition after 500 hours running .
  • the new bimetallic compositions according to the present invention reveal to be quite suitable for the preparation of fuel cells capable of excellent performance when operated under steam-reforming conditions .
  • Example 6 preparation of anode-supported SOFC structures Preparation of the Ni/YSZ porous anodic carrier
  • An aqueous suspension was prepared, having the following composition : Nickel (metallic phase) 78 g (INCO 255) 8-YSZ (ceramic phase) 42 g (Lonza) Metal/ceramic ratio 65/35% by weight
  • the powders were suspended in an aqueous solution of methyl cellulose (Fluka, 63000 cps) at 2.5% by weight and the suspension obtained (slurry) was homogenized by me- chanical stirring for 2 hours .
  • methyl cellulose Fluka, 63000 cps
  • the slurry is deaerated for 24 hours by continuous rotation of the container on rolls .
  • the slurry is poured into the basin of a sliding trolley (doctor blade) .
  • the trolley has two blades whose distance from the casting plane can be regulated by means of micrometric screws .
  • the width of the trolley basin automatically determines the width of the tape .
  • the rate of the trolley was regulated by an electric moving system and was established at 0.2 m/min .
  • the solution spread was dried at room temperature for 24 hours .
  • the tape thus obtained was cut so as to obtain test samples having dimensions of about 6 x 6 cm 2 and subj ected to a pressure of about 150 kg/cm 2 for ten minutes so as to obtain its mechanical settlement .
  • the tape is subj ected to a pre-sintering thermal cycle in air which comprises a first phase up to 600 0 C at a rate of 30 °C/h to remove the organic phase , followed by a rise of 20 °C/h up to the maximum temperature of 1200 0 C .
  • the nicked is oxidized, already at about 75O 0 C, and the end-product is therefore a porous carrier consisting of YSZ and NiO .
  • a further anodic layer having a thickness of about 20
  • Example 2 After drying the porous carrier with the anodic layer at 120 0 C, an electrolyte layer was deposited by screen printing a paste consisting of 150 g of 8 -YSZ and 53 g of the same ligand used
  • Example 1 ethyl cellulose at 14% by weight in ⁇ - terpineol
  • the semicell thus pre- pared was sintered at 1400 0 C according to a thermal cycle which comprises a first phase up to 600 0 C at a rate of 30 °C/h to remove the organic phase, following by a rise of 20 °C/h up to the maximum temperature of 1400 0 C .
  • a semicell was obtained, consisting of a po- rous/anode/electrolyte carrier, followed by the deposition and sintering at 1200 0 C of the cathodic layer as described in Example 1 to complete the preparation of the cell .
  • the cell has a structure essentially without fractures , demonstrating the advantageous behaviour with shrinkage in the sintering phase .
  • the "anode-supported" SOFC structure was subj ected to electric characterization according to the method described in Example 1.
  • the reduction phase activation of the porous carrier and anode
  • the SOFC was characterized according to the following procedure :
  • Anodic gas hydrogen, 0.5 litres/minute

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Materials Engineering (AREA)
  • General Chemical & Material Sciences (AREA)
  • Electrochemistry (AREA)
  • Ceramic Engineering (AREA)
  • Organic Chemistry (AREA)
  • Metallurgy (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • Manufacturing & Machinery (AREA)
  • Physics & Mathematics (AREA)
  • Composite Materials (AREA)
  • Powder Metallurgy (AREA)
  • Inert Electrodes (AREA)

Abstract

L'invention concerne un procédé de fabrication d'une composition céramique-métallique (cermet) composée d'au moins 70 % en poids de matériau solide contenant 35 à 70 % en poids d'une phase de nickel métallique et 65 à 30 % en poids d'au moins un oxyde choisi parmi des oxydes de métaux de transition et de lanthanides. Ledit procédé consiste i) à préparer un mélange de poudres contenant du nickel métallique et au moins un oxyde autre que de l'oxyde de nickel, choisi parmi des oxydes de métaux de transition et de lanthanides ; ii) à déposer ledit mélange de poudres sur une surface adaptée se présentant sous la forme d'une couche ayant une épaisseur de 2 à 1500 µm ; iii) à chauffer ladite couche dans des conditions d'oxydation jusqu'à obtention du degré de frittage souhaité ; et, iv) à réduire éventuellement l'oxyde de nickel du produit fritté en nickel métallique.
PCT/EP2005/014180 2004-12-23 2005-12-23 Procede de fabrication d'un cermet de nickel pour des cellules electrochimiques a oxydes solides WO2006066973A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
IT002468A ITMI20042468A1 (it) 2004-12-23 2004-12-23 Metodo per la preparazione di un cermet di nichel per celle a combustibile ad ossidi solidi
ITMI2004A002468 2004-12-23

Publications (2)

Publication Number Publication Date
WO2006066973A2 true WO2006066973A2 (fr) 2006-06-29
WO2006066973A3 WO2006066973A3 (fr) 2006-11-30

Family

ID=34956576

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2005/014180 WO2006066973A2 (fr) 2004-12-23 2005-12-23 Procede de fabrication d'un cermet de nickel pour des cellules electrochimiques a oxydes solides

Country Status (2)

Country Link
IT (1) ITMI20042468A1 (fr)
WO (1) WO2006066973A2 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2964664A1 (fr) * 2010-09-13 2012-03-16 Commissariat Energie Atomique Encre aqueuse pour la realisation d'electrodes de cellule electrochimique haute temperature
DE102011017594A1 (de) * 2011-04-27 2012-10-31 Siemens Aktiengesellschaft Verfahren zur Herstellung eines porösen Körpers und Zelle einer wieder aufladbaren Oxidbatterie

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
IT1248589B (it) * 1991-06-28 1995-01-19 Eniricerche Spa Cermet di nichel e procedimento per la sua preparazione
US5141825A (en) * 1991-07-26 1992-08-25 Westinghouse Electric Corp. Method of making a cermet fuel electrode containing an inert additive
IT1277439B1 (it) * 1995-08-04 1997-11-10 Eniricerche Spa Cernet di nichel e relativo procedimento di preparazione
US6589680B1 (en) * 1999-03-03 2003-07-08 The Trustees Of The University Of Pennsylvania Method for solid oxide fuel cell anode preparation
AUPS087502A0 (en) * 2002-03-04 2002-03-28 Ceramic Fuel Cells Limited Solid oxide fuel cell
JP3996861B2 (ja) * 2002-05-29 2007-10-24 京セラ株式会社 燃料電池セル及び燃料電池
US7022647B2 (en) * 2002-08-05 2006-04-04 Battelle Energy Alliance, Llc Methods of fabricating cermet materials and methods of utilizing same
WO2004049491A1 (fr) * 2002-10-25 2004-06-10 Antonino Salvatore Arico Pile a combustible a oxyde solide a anode de cermet et d'alliage cuivre/nickel

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2964664A1 (fr) * 2010-09-13 2012-03-16 Commissariat Energie Atomique Encre aqueuse pour la realisation d'electrodes de cellule electrochimique haute temperature
WO2012035226A1 (fr) 2010-09-13 2012-03-22 Commissariat A L'energie Atomique Et Aux Energies Alternatives Encre aqueuse pour la realisation d'electrodes de cellule electrochimique haute temperature
US9005488B2 (en) 2010-09-13 2015-04-14 Commissariat A L'energie Atomique Et Aux Energies Alternatives Aqueous ink for producing high-temperature electrochemical cell electrodes
DE102011017594A1 (de) * 2011-04-27 2012-10-31 Siemens Aktiengesellschaft Verfahren zur Herstellung eines porösen Körpers und Zelle einer wieder aufladbaren Oxidbatterie
EP2681343A2 (fr) * 2011-04-27 2014-01-08 Siemens Aktiengesellschaft Procédé de production d'un corps poreux et élément d'une batterie oxyde rechargeable
US9806327B2 (en) 2011-04-27 2017-10-31 Siemens Aktiengesellschaft Method for the production of a porous element, and cell of a rechargeable oxide battery

Also Published As

Publication number Publication date
ITMI20042468A1 (it) 2005-03-23
WO2006066973A3 (fr) 2006-11-30

Similar Documents

Publication Publication Date Title
Zha et al. Ni-Ce0. 9Gd0. 1O1. 95 anode for GDC electrolyte-based low-temperature SOFCs
Xia et al. Microstructures, conductivities, and electrochemical properties of Ce0. 9Gd0. 1O2 and GDC–Ni anodes for low-temperature SOFCs
AU747320B2 (en) Method for solid oxide fuel cell anode preparation
US8518605B2 (en) Ceramic material combination for an anode of a high-temperature fuel cell
Tietz et al. Evaluation of commercial nickel oxide powders for components in solid oxide fuel cells
US20060113034A1 (en) Electrochemical cell architecture and method of making same via controlled powder morphology
Vernoux et al. Catalytic and electrochemical properties of doped lanthanum chromites as new anode materials for solid oxide fuel cells
CN1442919A (zh) 用于燃料电池阳极的一种结构体
Zheng et al. Effect of Pd-impregnation on performance, sulfur poisoning and tolerance of Ni/GDC anode of solid oxide fuel cells
Yin et al. Gel-cast NiO–SDC composites as anodes for solid oxide fuel cells
Blennow et al. Development of planar metal supported SOFC with novel cermet anode
US20080280189A1 (en) Fabrication of Electrode Structures by Thermal Spraying
JP2015501515A (ja) 固体酸化物電気化学セル用の高性能燃料電極
AU2008207642A1 (en) Ceria and strontium titanate based electrodes
Wang et al. Inkjet printing infiltration of Ni-Gd: CeO 2 anodes for low temperature solid oxide fuel cells
Zhang et al. Enhanced electrochemical performance of BaZr0. 1Ce0. 7Y0. 1Yb0. 1O3− δ electrodes for hydrogen and methane oxidation in solid oxide fuel cells by Pd or Cu0. 5Pd0. 5 impregnation
Zare et al. Electrochemical evaluation of Sr2Fe1. 5Mo0. 5O6-δ/Ce0. 9Gd0. 1O1. 95 cathode of SOFCs by EIS and DRT analysis
CA2675988C (fr) Materiau composite adapte a une utilisation en tant que materiau d'electrode dans une pile a oxyde solide
Bi et al. Cu1− xPdx/CeO2-impregnated cermet anodes for direct oxidation of methane in LaGaO3-electrolyte solid oxide fuel cells
Rojek et al. Development of high performance anodes for metal-supported fuel cells
WO2006066973A2 (fr) Procede de fabrication d'un cermet de nickel pour des cellules electrochimiques a oxydes solides
Sciazko et al. Correlation Between Microstructure and Performance of GDC-Based Electrodes
RU2523550C1 (ru) Композитный электродный материал для электрохимических устройств
Torknik et al. Nanostructuring platinum nanoparticles on Ni/Ce0. 8Gd0. 2O2-δ anode for low temperature solid oxide fuel cell via single-step infiltration: a case study
JP7510669B2 (ja) 固体酸化物形セル用燃料極、積層構造体及びその製造方法、並びに固体酸化物形セル及びその製造方法

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A2

Designated state(s): AE AG AL AM AT AU AZ BA BB BG BR BW BY BZ CA CH CN CO CR CU CZ DE DK DM DZ EC EE EG ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KM KN KP KR KZ LC LK LR LS LT LU LV LY MA MD MG MK MN MW MX MZ NA NG NI NO NZ OM PG PH PL PT RO RU SC SD SE SG SK SL SM SY TJ TM TN TR TT TZ UA UG US UZ VC VN YU ZA ZM ZW

AL Designated countries for regional patents

Kind code of ref document: A2

Designated state(s): GM KE LS MW MZ NA SD SL SZ TZ UG ZM ZW AM AZ BY KG KZ MD RU TJ TM AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LT LU LV MC NL PL PT RO SE SI SK TR BF BJ CF CG CI CM GA GN GQ GW ML MR NE SN TD TG

DPE1 Request for preliminary examination filed after expiration of 19th month from priority date (pct application filed from 20040101)
NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 05824672

Country of ref document: EP

Kind code of ref document: A2

WWW Wipo information: withdrawn in national office

Ref document number: 5824672

Country of ref document: EP

点击 这是indexloc提供的php浏览器服务，不要输入任何密码和下载