PASSIVE HYDROGEN CAPTURE AND PROCESSING DEVICE WITH TRANSITION METAL OXIDE-BASED ACTIVE MATERIAL

Abstract

Structure for the treatment of hydrogen by recombination having at least one element (75A, 75B, 75C, 75D) of so-called "active" material (20) intended to react with hydrogen, the active material comprising a metal oxide MOx, with M a transition metal, with 1 < x < 5, the metal oxide MOx being capable of undergoing reduction in the presence of hydrogen and without the presence of oxygen so as to form water, and of forming as a product of this reduction another oxide MOx-1 capable of oxidizing in the presence of oxygen to reform the metal oxide MOx. Figure for the abstract: 9.

Description

Title of the invention: PASSIVE DEVICE FOR CAPTURING AND PROCESSING HYDROGEN WITH MATERIAL ACTIVE INGREDIENT BASED ON TRANSITION METAL OXIDE TECHNICAL FIELD AND PREVIOUS ART

[0001] The present invention relates to the field of hydrogen capture and processing, and in particular to passive hydrogen capture and processing devices such as recombiners. It specifically aims at an improved structure comprising a material enabling the recombination of hydrogen into water.

[0002] In several industrial sectors, hydrogen degassing poses a major problem, especially in restricted or confined environments, with potentially serious consequences.

[0003] Such a phenomenon can lead to the swelling of containers or receptacles, the weakening of materials.

[0004] The presence of gaseous dihydrogen also proves dangerous in certain situations and locations where hydrogen is likely to interact with oxygen. A significant risk of fire or explosion then exists.

[0005] In certain particularly sensitive locations such as nuclear power plants, fuel storage sites, or radioactive waste treatment facilities, this risk is increased, notably due to potential radiolysis of the water. Such a phenomenon leads to the formation of both hydrogen and oxygen, which can interact and cause the aforementioned damage.

[0006] Capture devices have been proposed to reduce the concentration of dihydrogen by causing its recombination.

[0007] Among these devices, passive autocatalytic recombiners have been developed. Their operation is based on the consumption of hydrogen using catalytic plates made of noble metal. Such a device is presented, for example, in document WO / 2018 / 009092.

[0008] Such a device has the particular advantage of being passive and able to operate without human intervention or even power supply, in particular electrical, and of having good durability, without frequent need for maintenance or replacement of the plates.

[0009] However, it poses cost problems due to the large quantity of noble metal needed to make the catalytic plates, and the large size of these plates.

[0010] Such a device also has a restrictive limitation in terms of the minimum hydrogen concentration from which it operates, this concentration typically being at least a concentration of 0.5% v / v (volume on volume) of hydrogen. Description of the invention

[0011] It is therefore an object of the present invention to offer a structure for the treatment of hydrogen by recombination and having one or more elements in an improved "active" material with respect to at least one of the aforementioned disadvantages.

[0012] The inventors have discovered in particular an active material comprising a metal oxide MOX, with M a transition metal, with 1 < x < 5, the metal oxide MOX being capable of undergoing reduction in the presence of hydrogen and without the presence of oxygen so as to form water, and of forming as a product of this reduction another oxide MOx.i capable of oxidizing in the presence of oxygen to reform the metal oxide MOX.

[0013] The metal M is also typically chosen here such that the standard potential E°(M0x / M0x.i) of the M0x / M0x i couple is located between that E°(H2O / H2) of the H2O / H2 couple and that E°(O2 / H2O) of the O2 / H2O couple. Thus, the metal M is such that the standard potential E°(M0x / M0x i) of the M0x / M0x couple is typically between -0.828 V / ESH and +1.229 V / ESH, and preferably between -0.5 and +0.5 V / ESH.

[0014] An element made of such an active material is significantly less expensive than when it is made solely of noble metal, while also exhibiting good durability and reduced size.

[0015] It also has the advantage of reacting even at very low concentrations of hydrogen and oxygen. A reaction can be carried out at a dihydrogen concentration of less than 2% v / v, and in particular less than 0.5% v / v and down to at least 0.03% v / v.

[0016] Advantageously, the active material is a compound based on said metal oxide MOX and a catalyst, this catalyst being in particular a metal from group VIII or group I, preferably chosen from the following metals: Pt, Pd, Ni, Cu, Ag, Au. In this case, the hydrogen recombination reaction to form water vapor can advantageously be carried out at room temperature, without the input of heat.

[0017] Advantageously, the metal oxide MOX can be WO3. Tungsten trioxide is highly reactive with dihydrogen, and in its WO2 form is highly reactive with oxygen, reforming WO3, while exhibiting good thermal and chemical resistance. Such a material is also non-toxic and inexpensive.

[0018] Advantageously, the active material is a compound of WO3 and Pt or Pd as a catalyst. The presence of the catalyst allows recombination at room temperature or even lower.

[0019] Advantageously, the active material can be porous, in particular macroporous and / or mesoporous and / or microporous, with pores whose largest dimension or diameter is typically between 10 and 0.1 pm, and even more advantageously in a range of 1 and 0.4 pm.

[0020] According to a particular embodiment, the active material may be in the form of a block coated with a water-permeable porous coating. For example, the water-permeable porous coating may be in the form of a metallic or polymer foam or a porous glass.

[0021] According to another particular embodiment, the active material can be covered with a coating permeable to hydrogen and oxygen and impermeable to water.

[0022] For example, the porous coating permeable to hydrogen and oxygen and impermeable to water, may be in the form of a functionalized metallic foam having a hydrophobic surface, or a hydrophobic porous polymer.

[0023] According to another particular embodiment, the active material may be in the form of particles or inclusions integrated into a porous material permeable to hydrogen and oxygen.

[0024] According to another particular embodiment, the active material may be in the form of a fibrous support such as glass wool or formed of microfibers or nanofibers, in particular of SiC microfibers or nanofibers, or of metal or carbon, the fibrous support being coated with the active material or incorporating the active material.

[0025] According to another aspect, the present invention relates to a passive dihydrogen recombiner comprising at least one structure for hydrogen treatment and as defined above.

[0026] According to another aspect, the present invention provides for an installation for the storage or treatment of nuclear waste or the exploitation of nuclear fuel and comprising at least one passive recombiner as defined above or a structure for the treatment of hydrogen as defined above.

[0027] According to another aspect, the present invention provides a corium catcher comprising at least one structure for hydrogen treatment as defined above.

[0028] According to another aspect, the present invention provides a radioactive waste storage package containing a structure for hydrogen treatment as defined above. Brief description of the drawings

[0029] The present invention will be better understood on the basis of the following description and the accompanying drawings in which:

[0030] [Fig.1A] [Fig.1B] serve to illustrate an example of a recombiner having elements of particular active material based on transition metal oxide and capable of reacting with hydrogen, without the presence of oxygen, and by recombination producing water.

[0031] [Fig.2] serves to illustrate an example of a transition metal oxide-based active material block.

[0032] [Fig.3] serves to illustrate an example of a particular structure formed of a block of active material based on a transition metal oxide and capable of reacting with hydrogen, this block being coated with a material permeable to hydrogen, oxygen and water.

[0033] [Fig.4] serves to illustrate an example of a particular structure in which the block of active material is coated with a material permeable to hydrogen, oxygen and impermeable to water.

[0034] [Fig.5] serves to illustrate an example of a particular structure of active material integrated in the form of particles or inclusions in a material permeable to hydrogen, oxygen and impermeable to water.

[0035] [Fig.6] serves to illustrate an example of a particular structure in which the active material is integrated in the form of particles or inclusions in a material permeable to hydrogen, oxygen and water.

[0036] [Fig.7] serves to illustrate a functionalized fibrous support incorporating the active material.

[0037] [Fig.8] serves to illustrate an example of the recombination kinetics of an active material particular.

[0038] [Fig.9] serves to illustrate an example of a corium catcher comprising several zones of active material based on transition metal oxide and capable of reacting with hydrogen by recombination to produce water.

[0039] [Fig.1OA] [Fig.1OB] [Fig.1OC] respectively illustrate an integration of active material into a waste storage facility containing at least one radioactive package, and the integration of the active material into at least one radioactive waste storage package.

[0040] Identical, similar or equivalent parts of the different figures bear the same numerical references so as to facilitate the transition from one figure to another.

[0041] The different parts represented in the figures are not necessarily shown on a uniform scale, in order to make the figures more legible.

[0042] DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

[0043] An example of a recombiner 10 according to the invention, comprising at least one structure of so-called "active" material capable of reacting with hydrogen, is schematically represented in Figures IA and IB.

[0044] The recombiner 10 can be suspended in a site or enclosure to be protected, for example a nuclear power plant, or a place of storage of nuclear waste or material likely to generate hydrogen degassing or even hydrogen degassing by radiolysis of water, or a site of production and / or use of hydrogen as an energy carrier.

[0045] In the example illustrated in [Fig. 1 A], the recombiner 10 is intended for wall mounting. Alternatively, it can be supported and suspended by another type of structure, for example a bracket, or simply placed on a support, for example on the floor.

[0046] The recombiner 10 comprises a chassis 13 housing, in the illustrated example, one or more elements 15A, 15B, 15C, 15D of active material 20, the composition of which will be detailed later. The elements 15A, 15B, 15C, 15D are, for example, in the form of blocks or plates made of active material 20 or comprising at least one zone or layer of active material 20.

[0047] The chassis 13 is internally provided with at least one conduit 14 in which the elements 15A, 15B, 15C, 15D are arranged and which extends between at least one opening 17, referred to as the "inlet" opening, and at least one other opening 19, referred to as the "exhaust" opening. During operation, hydrogen H2 is passively drawn in (arrow(s) Fl) through at least one inlet opening 17, and a reduction reaction occurs with the active material of the elements 15A, 15B, 15C, 15D to generate water vapor (arrow(s) F2), which vapor exits through the upper end of the conduit via the exhaust opening 19. The arrows Fl and F2 in Figures IA and IB show a preferred flow direction resulting from natural circulation, further enhanced by a thermal gradient due to heat release during the reaction. The operation of the recombiner 10 is thus based on physico-chemical principles to initiate and maintain the recombination reaction.Recombiner 10 is described as "passive" because it can operate autonomously without an external power source, particularly without electricity, and does not require control, intervention, or actuation during its operation.

[0048] The elements 15A, 15B, 15C, 15D can be integrated in various ways into the chassis 13 of the recombiner 10, typically in a removable manner, for example by means of a sliding structure.

[0049] The active material 20 here has the particularity of being a transition metal oxide MOx (with M a transition metal such as, for example: W, Mo, Ti, Ce, Ni, Sn, Cu and with x typically greater than 1 and less than 5) chosen so that it can be reduced in the presence of hydrogen and recombine to create water molecules.

[0050] In particular, a metal is chosen such that the couple M0x / M0x i has a standard electrochemical potential E°(M0x / M0x i) between the standard potential of the couple H2O / H2 and that of the couple O2 / H2O which are between -0.8 and +1.22 V / ESH respectively.

[0051] Advantageously, the metal M is chosen such that the standard electrochemical potential E°(M0x / M0x i) of the couple M0x / M0x2 is in a range between -0.6 V / ESH and +1.0 V / ESH and even more advantageously in a range between -0.5 V / ESH and +0.5 V / ESH.

[0052] Two other physicochemical characteristics can be taken into account when selecting the metal oxide MOX, namely the activation energy (Ea) of the reaction between the metal oxide (MOX) and hydrogen (H2(g)) and the exothermicity of the reduction and oxidation (these reactions corresponding to reactions 2 and 3 given below). The lower the Ea value, the higher the reaction kinetics. The higher the exothermicity of the reduction and oxidation of the metal couple by H2(g), the more efficient the principle.

[0053] The transition metal oxide MOX allows this recombination to take place, both in the presence of a catalyst and in the absence of a catalyst, according to one or the other of the following reactions 1 or 2 given below:

[0054] Mn xw Mn JLHsanscatalyseur)Æéacôozil MUx W + (g) MUX-} (s)+ H+ y [mol /

[0055] rr z» kj \ (with catalyst) Reaction 2

[0056] Q and Q' correspond respectively to heat released during reaction 1 and during reaction 2.

[0057] The catalyst-free reaction occurs particularly at temperatures on the order of several hundred °C, for example, between 400 °C and 600 °C. The active material 20 also has the particularity and advantage of being able to react with hydrogen even when the oxygen concentration is low, for example, on the order of 2% v / v or even in the total absence of oxygen. Another advantage related to the use of a transition metal oxide MOX as defined above is that, in the presence of oxygen, a metal oxide MOX i produced by a reduction reaction defined above is capable of oxidizing to reform the metal oxide MOX. A re-oxidation to reform the reactant, in other words, the starting transition metal oxide MOX, can thus be carried out according to the following reaction:

[0058] ^-1(,)+ O2W- 2MO,w+eS) Reactim3

[0059] This contributes to the durability of elements 15A, 15B, 15C, 15D. The transition metal oxide-based material can be, for example, tungsten oxide (WO3), titanium oxide (TiO2), molybdenum oxide (MoO3), or tin oxide (SnO2). The various metal oxides mentioned have optimal standard potentials around 0 V / ESH.

[0060] Another advantage of the aforementioned active material 20 is that it allows reaction with hydrogen at low hydrogen concentrations typically between 1.81 and 0.03% v / v, and which can thus be less than 0.5% v / v.

[0061] According to a particularly advantageous embodiment, the active material 20 can be based on tungsten trioxide (WO3). In the specific case where the active material elements 15A, 15B, 15C, 15D are based on tungsten trioxide (WO3), the following reaction can be carried out: [°°621 W3w+ WO2w+H2O +Q^)

[0063] Reaction 4 (special case where the active material is devoid of a catalyst)

[0064] The catalyst-free metal oxide compound material can be used in the case of a high-temperature environment, in particular between 400°C and 600°C.

[0065] According to a preferred embodiment, the active material 20 is a compound based on MOX and a catalyst. In this case, advantageously, the reduction reaction can take place at room temperature without the input of heat. The catalyst is typically metallic and based on at least one metal from group VIII or I, in particular selected from the following metals: Ru, Rh, Ir, Pd, Pt, Ni, Cu, Ag, Au.

[0066] In ascending order of preference (an order which may be dictated in particular by both cost and melting temperature criteria) the metal is chosen from the following list: Au, Ag, Cu, Ni. More advantageously, the catalyst may be based on Platinum (Pt) or Palladium (Pd).

[0067] Thus, according to a particularly advantageous embodiment, the elements 15A, 15B, 15C, 15D can be based on tungsten trioxide (WO3) and a catalyst such as, for example, Platinum or Palladium.

[0068] The following reaction can then be implemented:

[0069]

[0070] (with catalyst, with Q the heat released by the chemical reaction in kJ / mol). The reduction reaction (reactions 4 and 5) of tungsten trioxide is exothermic.

[0071] With or without a catalyst, when the active material 20 is tungsten trioxide (WO3), the following reaction can be implemented at elements 15A, 15B, 15C, 15D: 100721 ​​2WOm+ 2WO^,}+^ Réaaion6

[0073] Thus, when tungsten trioxide is reduced by hydrogen to form tungsten dioxide, the latter is rapidly re-oxidized by the presence of oxygen. This reaction (reaction 6) is also exothermic.

[0074] The two types of reaction (reaction 4 or reaction 5 on the one hand, and reaction 6 on the other hand) appear simultaneously and allow continuous consumption when hydrogen and oxygen are present in significant quantities.

[0075] The active material 20 can be produced, for example, using a sol-gel type process.

[0076] The document: “Electrochromic properties of sol-gel derived WO3 coatings”, by P. Judeinstein and J. Livage, in Sol-Gel Optics, SPIE, 1990, p. 344-351. doi: 10.1117 / 12.22573, gives an example of the realization of WO3 by sol-gel process.

[0077] An example of the fabrication of a compound of WO3 and Pd is given in the document "A fiber-optic evanescent-wave hydrogen gas sensor using palladium-supported tungsten oxide", by S. Sekimoto et al., Sens. Actuators B Chem., vol. 66, no. 1, p. 142-145, 2000, doi: 10.1016 / 80925-4005(00)00330-0.

[0078] The document “Fiber optic hydrogen sensors with sol-gel WO3 coatings”, by Yang, Z. Yang, J. Dai, and D. Zhang Sens. Actuators B Chem., vol. 166-167, p. 632-636, 2012, doi: 10.1016 / j.snb.2012.03.026, gives an example of the realization of a compound of WO3 and Pt as a catalyst.

[0079] A specific example of a sequence of steps in a manufacturing process for an active material coating using the Sol-Gel method will now be given. In this particular case, the active material can be deposited onto a substrate, for example, a plate, or a fibrous substrate made of nanofibers and / or microfibers of glass, SiC, or polymer. Alternatively, the active material can be formed directly as an active powder following solvent evaporation.

[0080] According to a first step, a solution containing a metal oxide is acidified. This acidification can be carried out using, for example, a cation exchange resin which is brought into contact with the solution. For example, the acidification of a 13 mL 0.5 M sodium tungstate (Na₂WO₄) solution can be performed to obtain a solution containing a precursor, in this case H₂WO₄aq. A solvent, typically organic, is then added. This solvent can be, for example, ethanol, in a volume that can be, for example, on the order of 8 mL for the aforementioned volumes of precursor and catalyst solutions respectively.

[0081] The solution containing this precursor is recovered, to which another solution containing a catalyst is added. In a particular example, this other solution could be a solution of H2PtCl6. A volume of 4 mL at 0.125 M could, for example, be used, resulting in an atomic proportion of 1:13 of catalyst: WO3. This proportion corresponds to an optimal proportion for a good reaction while minimizing the amount of catalyst to be used.

[0082] A coating based on an amorphous MOX oxide, here amorphous WO3, is then formed using the previously obtained solution. A process commonly known as "Dip-Coating," in which the substrate is immersed in the previously obtained solution, can be used to deposit the coating onto the substrate. Alternatively, a process such as "Spin-Coating" can be used to deposit the coating onto a flat surface. The active coating in powder form can be obtained by evaporating the solvent. To accelerate the evaporation process, the solution can be heated to a temperature, for example, between 50°C and 60°C and / or placed under vacuum using, for example, a rotary evaporator.

[0083] Such a process typically includes a coating drying step, which can be carried out under ambient air or heated to a temperature of, for example, between 50°C and 60°C in order to accelerate the process, for example for a period of several hours, for example 2 hours.

[0084] A calcination step is then typically carried out. The purpose of this step is twofold: first, the tungsten trioxide is converted into a crystalline form, creating vacancies. The presence of such vacancies is favorable to the reactivity of the material. Finally, if the catalyst is introduced in the form of H2PtCl6 or any other form in solution, calcination is performed to break the bonds between the chlorine and platinum and to reduce the platinum to its metallic form, i.e., its catalytically active form. Such a heat treatment is typically carried out at a temperature on the order of several hundred degrees Celsius, for example, typically between 300°C and 650°C, for a duration typically of at least several tens of minutes, for example, typically between 10 and 90 minutes. Advantageously, such treatment is carried out between 450 °C and 550 °C for a duration of between 30 and 60 min.

[0085] According to an advantageous embodiment, an active material 20 porous and in particular meso- and / or micro-porous can be provided.

[0086] In order to increase the specific surface area of ​​the material obtained and to increase or create porosity, a "Soft-Templating" (i.e. "soft matrix") or "hard-templating" (i.e. "hard matrix") type method can be used and possibly integrated into a process as described above.

[0087] It is thus possible to introduce molecules or molecular assemblies to form a so-called "sacrificial" phase in a solution such as mentioned above containing a precursor, for example of H2WO4aq.

[0088] A solidification of the precursor is implemented, for example during a cooking step, for example by calcination as described above, to form a composite material where sacrificial regions are trapped in an inorganic matrix or skeleton based on MOX oxide or on MOx oxide and the catalyst.

[0089] The sacrificial regions are then eliminated to retain only the MOX oxide and catalyst-based material.

[0090] When using a hard-templating method, the sacrificial phase is itself typically inorganic. For example, silicon or silica (SiO2) in powder form with a grain size typically less than 1 pm can be used to form the sacrificial phase which is added to a solution containing a precursor H2WO4aq and the catalyst H2PtCl6.

[0091] A catalyst-doped oxide coating, here WO3 / Pt, is then formed in free spaces around the sacrificial phase, for example Si or SiO2. Then, after calcination, the sacrificial phase is typically removed by dissolution using a hydrofluoric acid (HF) solution, for example 10%. This yields a metal oxide that can be catalyst-doped, here a WO3 / Pt composite material with porosity formed by the removal of sacrificial regions, here silicon or silica.

[0092] The document “Nanostructured Tungsten Oxide - Properties, Synthesis, and Applications”, by H. Zheng, et al., Adv. Funct. Mater., vol. 21, no. 12, pp. 2175-2196, 2011, doi: 10.1002 / adfm.201002477, gives an example of the fabrication of porous WO3 using a “Soft Templating” method. Fabrication of a WO3 / Pt composite material using a similar method is also possible.

[0093] The active material compound 20 based on metal oxide MOX^ advantageously associated with a catalyst can be in the form of a block as illustrated in [Fig.2].

[0094] In one embodiment, the active material block 20 is at least partially covered with a coating 30 that is permeable to gases, in particular to hydrogen and oxygen, and permeable to water.

[0095] In this case, the water produced during the reaction of hydrogen with the active material 20 can be more easily drained away. This permeable coating 30 can be a A porous material, advantageously with high porosity, and a skeleton or matrix that can be metallic, ceramic, or polymer. For example, the coating 30 can be a metallic foam, e.g., copper, or stainless steel, e.g., type 304L or 316L. Such a foam can be produced, for example, by 3D powder bed printing or by a conventional technique for manufacturing metallic foam or porous filters. As another example, the coating 30 can be based on a hydrophilic porous polymer, e.g., polyvinyl alcohol (CAS: 9002-89-5). Another embodiment involves a coating based on porous glass, typically sintered glass.

[0096] In the particular embodiment illustrated in [Fig.3], the active material 20 is in the form of a block entirely covered by the permeable coating 30.

[0097] According to another embodiment, the active material 20 is at least partially covered with a coating 40 permeable to hydrogen and oxygen but this time impermeable to water.

[0098] In the particular embodiment illustrated in [Fig.4], the active material 20 is arranged to form a sheath of a channel covered by the coating 40 which is permeable to hydrogen and oxygen and impermeable to water.

[0099] In this case, the water produced during the reaction of hydrogen with the active material can be retained in the channel or discharged through the channel. The water-impermeable coating 40 can, for example, consist of a single layer of molecules ("self-assembled monolayer" or SAM), for example, an alkanethiolate layer, or be based on alkylphosphonic acid(s). According to a particular embodiment, the coating 40 can be a porous, hydrophobic metallic material such as porous steel or hydrophobic porous copper. A low-carbon steel, for example, 316L steel with less than 0.03% carbon, can be functionalized, for example, with octadecanethiol (ODT; Ci8H37SH: CAS No. 2885-00-9) after first quenching the steel in hydrochloric acid to remove the passivation layer.The coating 40 may also be in the form of hydrophobic or hydrophobic cotton or functionalized foam having a hydrophobic surface, in particular metallic foam or hydrophobic porous polymer-based foam for example a fluorocarbon polymer such as Teflon™, or a polymer such as polyvinylidene fluoride (CAS: 24937-79-9).

[0100] A process such as described for example in the document "The nature of self-assembled octadecylphosphonic acid (ODPA) layers on copper substrates" by Zhao et al., Journal of Colloid and Interface Science Volume 581, Part B, 1 January 2021, Pages 816-825 can be used for example to functionalize and make hydrophobic copper or another metal or even a metal oxide using an alkylphosphonic acid (ODPA).

[0101] As an alternative to either of the embodiments described above, rather than being in the form of block(s) or layer(s), the active material 20, based on transition metal oxide MOX or based on a compound of transition metal oxide MOX and catalyst, may be in the form of inclusions or particles integrated into a porous material permeable to hydrogen and oxygen.

[0102] In the embodiment illustrated in [Fig. 5], particles 120, with a maximum dimension or width dlm, for example, between 1 micrometer and 1 decimeter, advantageously between 50 pm and 2 cm of active material 20, are integrated into a porous material 400, permeable to hydrogen and oxygen but impermeable to water. This material 400 may, for example, be of the type used to form the coating 40 described previously in connection with [Fig. 4].

[0103] A method for obtaining this configuration in which the active material 120 is incorporated into a functionalized and hydrophobic metallic foam includes additive manufacturing or a sintering technique.

[0104] In the embodiment illustrated in [Fig. 6], particles 120' of active material 20 with a maximum dimension or width d2m, for example, between 1 micrometer and 1 decimeter, advantageously between 50 µm and 2 cm, are integrated into a porous material 300, permeable to hydrogen, oxygen, and water. This material 300 can, for example, be of the type used to form the coating 30 described previously in connection with [Fig. 3].

[0105] In the embodiment illustrated in [Fig. 7], the active material 20 is arranged in the form of particles on a functionalized fibrous support 52. The fibrous support 52 forms a filter and is, for example, based on glass fibers or made of SiC microfibers or nanofibers, or of metal or carbon. The support 52 may have pores, for example, of micrometric size, for example between A and B. The particles of active material 20 may be incorporated into the pores.

[0106] In the particular embodiment illustrated, the fibrous support 52 has a circular plate shape, but other shapes, possibly planar, can be provided. The active material 20 on the fibrous support 52 can, for example, be deposited in powder form.

[0107] According to one embodiment, the active material 20 can be arranged on the support 52, for example by depositing a Sol-Gel solution containing the material 20 on one face of the support 52 and creating a vacuum on the opposite face. Drying for a period of, for example, at least 24 hours can then be provided. In order to accelerate such a drying step, the functionalized support 52 can be heated to a temperature, for example, between 50°C and 80°C for a period of, for example, between 2 and 24 hours, or placed under vacuum for a period of, for example, between 5 and 24 hours. The support 52 can then be subjected to a calcination step at a temperature between example between 300 and 600 °C, advantageously between 450 and 550 °C for a duration between 30 and 90 minutes.

[0108] One or the other configuration is chosen depending on the application and the context. An active material coating can be used both in a device or installation where the water produced by the reaction is released, and in a device or installation where the water is retained by a sponge effect.

[0109] Figure 8 shows a Ci curve illustrating the recombination kinetics of a given active material introduced into a measuring cell. In this example, the active material consists of 7 mg of a Pt / WO3 compound with a molar ratio of 1 / 13, exposed to a volume of 625 mL of hydrogen at atmospheric pressure with a concentration of 1.81 ±0.04% v / v hydrogen. The estimated temperature (in °C) of the active material is shown on the left y-axis, while the estimated hydrogen concentration (in % v / v) is shown on the right y-axis. The portion of the Ci curve before 0 s corresponds to a gaseous purge of 1.81% v / v hydrogenated air at a flow rate of 300 L / h. From 0 s onward, this gaseous purge is stopped, and the cell is closed at both the inlet and outlet. A static measurement is thus performed.

[0110] An active material 20 as previously described can be used in multiple applications and / or installations in which an undesirable emission of dihydrogen is likely to occur.

[0111] A hydrogen-active material such as the one presented above is, for example, particularly advantageous in a corium catcher installed in a nuclear power plant to mitigate a case of reactor core meltdown.

[0112] An example of a corium catcher is schematically represented in [Fig.9].

[0113] The condenser here comprises sacrificial structures 71a, 71b, for example made of concrete, and in particular a sacrificial separation structure 71b with a discharge channel 72 whose walls are coated with a protective layer 73. In the event of a reactor core meltdown and rupture of the sacrificial structure 71b, the corium falls by gravity into the discharge channel 72, which communicates with a spreading chamber 74 designed to promote cooling. The spreading chamber 74 can be partially filled with water and equipped with cooling plates 77. During the release of the corium, significant hydrogen production may occur due to the high temperature rise of various metallic parts, for example zirconium cladding, and when water is present in the vapor phase. The water is then likely to oxidize certain metals by forming hydrogen.

[0114] The active material 20 mentioned above is, in the particular embodiment illustrated, distributed over different zones 75A, 75B, 75C, 75D of the installation to allow passive hydrogen recombination.

[0115] According to another application example, a hydrogen-active material 20 as previously presented can also be integrated into a deep geological repository for radioactive waste, in particular of the High Activity (HA) type or of the Intermediate Activity and Long Life (IA-LL) type.

[0116] In the context of deep geological disposal of high-level (HLW) or intermediate-level long-lived (ILW-LL) radioactive waste, waste is likely to emit hydrogen within waste packages. This emission is problematic due to the risks of fire (typically from 4% v / v hydrogen) or explosion (generally from 13% v / v hydrogen), but also of degradation of the metal container at concentrations even lower than those mentioned above for a fire.

[0117] The hydrogen-based active material 20 presented above can be disposed of in different areas of a waste storage facility.

[0118] Thus, in the particular embodiment shown in [Fig. 1OA], regions 85A, 85B of active material 20 are arranged on the internal walls of a cell 80 for receiving packages 82 of radioactive waste, typically located underground. As illustrated in Figures 10B and 10C, the active material 20 can also be integrated into packages 84, 86 of radioactive waste.

[0119] Thus, on [Fig. 10B], a package 84 called "compacted" of radioactive waste for example of type MA-VL contains on an internal wall a region 85D of active material 20. On [Fig. 1OC], a package 86 called "vitrified" of radioactive waste for example of type HA contains on an internal wall, a region 85E of active material 20.

Claims

Demands

1. A recombination hydrogen treatment structure having at least one element (15A, 15B, 15C, 15D, 75A, 75B, 75C, 75D, 85A, 85B, 85C, 85D) of an "active" material (20) intended to react with hydrogen, the active material comprising a metal oxide MOX, with M a transition metal, with 1 < x < 5, the metal oxide MOX being capable of undergoing reduction in the presence of hydrogen and without the presence of oxygen so as to form water, and of forming as a product of this reduction another oxide MOX i capable of oxidizing in the presence of oxygen to reform the metal oxide MOX.

2. Structure according to claim 1, the active material (20) being a compound based on said metal oxide MOX and a catalyst, the catalyst being in particular a metal from group VIII or group I, preferably selected from the following metals: Pt, Pd, Ni, Cu, Ag, Au.

3. Structure according to one of claims 1 or 2, the metal oxide MOX being WO3.

4. Structure according to claim 3 when related to claim 2, the catalyst being Pt or Pd.

5. Structure according to any one of claims 1 to 4, the active material (20) being porous, in particular microporous and / or mesoporous.

6. Structure according to any one of claims 1 to 5, wherein said active material (20) is in the form of a block coated with a water-permeable porous coating (30), such as a metallic or polymer-based foam or a porous glass.

7. Structure according to any one of claims 1 to 5, wherein said active material (20) is covered with a coating (40) permeable to hydrogen and oxygen and impermeable to water, such as a functionalized metallic foam having a hydrophobic surface, or a hydrophobic porous polymer.

8. Structure according to any one of claims 1 to 4, wherein said active material (20) is in the form of particles or inclusions integrated into a porous material (300, 400) permeable to hydrogen and oxygen.

9. Structure according to any one of claims 1 to 4, comprising a fibrous support such as glass wool or made of microfibers

10.

11.

12.

13. or SiC, metal, or carbon nanofibers, the fibrous support being coated with the active material (20) or incorporating the active material (20). Passive dihydrogen recombiner (10) comprising at least one structure (15A, 15B, 15C, 15D) according to any one of the preceding claims. Installation for the storage or treatment of nuclear waste or the operation of nuclear fuel comprising at least one passive recombiner (10) according to claim 9 or a structure according to any one of claims 1 to 8. Corium catcher comprising at least one structure according to any one of claims 1 to 9. Radioactive waste storage package(s) containing a structure according to one of claims 1 to 9.

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