Method for controlling the storage and radioactive activity of a gas adsorbed by a porous material, associated installation, hydrated porous material and method for preparing it

Abstract

The invention relates to a process for preparing a hydrated porous material from a porous material comprising metallo-organic networks formed of inorganic subunits constituted by Zn4O and linked together by organic ligands chosen from dicarboxylic acids, which process comprises: (i) contacting the porous material with an atmosphere having a relative humidity of between 20% and 95% and being at a temperature of between 15°C and 40°C, and (ii) recovering the hydrated porous material, the dicarboxylic acids being chosen from terephthalic acid, 2,6-naphthalenedioic acid, 1,6-biphenyldioic acid, 1,8-terphenyldioic acid, 9,10-anthracenedioic acid, 2,7-pyrenedioic acid, 9,10-di(para-benzoic)-anthracene acid, 2,5-bis-(para-benzoic)-1,3,4-oxadiazole acid, a dicarboxylic derivative of 2,5-diphenyloxazole, a dicarboxylic derivative of 1,4-bis(5-phenyloxazol-2-yl) and a dicarboxylic derivative of carbazole. The invention also relates to a hydrated porous material. No figure,

Description

Title of the invention: Method for controlling the storage and radioactive activity of a gas adsorbed by a porous material, associated installation, hydrated porous material and its preparation method Technical field

[0001] The present invention relates to a method for controlling not only the storage of a radioactive gas within a porous material but also the measurement of the activity of the radioactive gas stored within this porous material.

[0002] In the context of the present invention, the radioactive gas is more particularly stored within the porous material by adsorption of this radioactive gas by the porous material.

[0003] The present invention also relates to an installation for controlling the storage and radioactive activity of a radioactive gas, this radioactive gas being adsorbed by a porous material. This installation is more particularly suitable for implementing the method for controlling storage and radioactive activity mentioned above.

[0004] The present invention also relates to a particular porous material as well as to its preparation process. This particular porous material is entirely suitable for implementing the method for controlling the storage and radioactive activity of the radioactive gas adsorbed by it. State of the prior art

[0005] Among the many porous materials that exist, those characterized by high porosity and specific surface area are capable of adsorbing, or even storing, gases.

[0006] For about twenty years, an emerging class of new porous materials exhibiting these porosity properties has emerged. These are metal-organic networks which are commonly referred to by the terms "MOF" and "MOFs" corresponding to the acronym of the Anglo-Saxon terminology "metal organic framework(s)".

[0007] These porous materials are formed of inorganic subunits linked together by organic ligands via strong iono-covalent interactions, defining a crystallized structure. Composed of one or more metal cations, the inorganic subunits act as crosslinking nodes. The number of coordination sites and their relative orientation define the geometry of the structure. For the choice of organic ligands, it is possible to take advantage of everything that organic chemistry offers, provided that the organic ligands have at least two complexing functions that can interact with inorganic subunits.

[0008] The organic-inorganic hybrid nature gives these porous materials many properties that are modifiable and modulatable depending on the choice of inorganic subunits and organic ligands. One of the reasons for the rise of MOFs is their ability to adsorb, store and even selectively adsorb any type of gas.

[0009] To control the radioactive activity of radioactive gases adsorbed by MOFs, document US 7,985,868 B1 reports the synthesis of two porous MOF-type materials exhibiting scintillation properties through the presence of scintillating organic ligands. The first porous material is characterized by an interesting specific surface area of ​​the order of 500 m2.g 1 but by a low scintillation efficiency which is 9% compared to anthracene, which represents 1500 ph / MeV. The second porous material is characterized by a better scintillation efficiency, in this case 22% compared to anthracene, which represents approximately 3600 ph / MeV, but its specific surface area is not reported because it is probably poor.

[0010] However, in the case of spectroscopic monitoring of radioactive gas, a scintillation efficiency of 1500 ph / MeV is a blocking value for the detection of certain types of gas, in particular those whose radioactive emission is energetically low (less than 50 keV).

[0011] The aim of the present invention is therefore to overcome the limitations of the porous materials described in document US 7,985,868 B1 and to propose a method which makes it possible to control the radioactive activity of the radioactive gases adsorbed in a porous material of the MOF type or its derivatives, regardless of the type of radioactive gases adsorbed by this porous material.

[0012] Another aim of the invention is to propose that this method also makes it possible to control the storage of these same radioactive gases within these porous materials of the MOF type or their derivatives. Statement of the invention

[0013] These and other aims are achieved, firstly, by a method for controlling the storage and radioactive activity of a radioactive gas adsorbed by a porous material having scintillation properties.

[0014] The method for controlling storage and radioactive activity according to the invention comprises the following steps: (a) placing the porous material in an enclosure, (b) circulation of the radioactive gas within the enclosure, whereby the radioactive gas is adsorbed by the porous material, (c) monitoring the adsorption of the radioactive gas by the porous material by monitoring the scintillation of the porous material, up to an adsorption level, this adsorption level advantageously corresponding to the saturation of radioactive gas adsorbed by the porous material, (d) interruption of the circulation of radioactive gas in the enclosure when the adsorption level is reached,

[0015] (e) evacuating the enclosure, and (f) monitoring the radioactive activity of the radioactive gas adsorbed by the porous material at the end of step (c) by monitoring the scintillation of the porous material,

[0016] the porous material comprising metallo-organic networks formed of inorganic subunits linked together by organic ligands, the inorganic subunits being constituted by Zn4O and the organic ligands being chosen from terephthalic acid, 2,6-naphthalenedioic acid, 1,6-biphenyldioic acid, 1,8-terphenyldioic acid, 9,10-anthracenedioic acid, 2,7-pyrenedioic acid, 9,10-di(para-benzoic)-anthracene acid, 2,5-bis-(para-benzoic)-1,3,4-oxadiazole acid, a dicarboxylic derivative of 2,5-diphenyloxazole, a dicarboxylic derivative of 1,4-bis(5-phenyloxazol-2-yl) and a dicarboxylic derivative of carbazole.

[0017] By "dicarboxylic derivative" of 2,5-diphenyloxazole, 1,4-bis(5-phenyloxazol-2-yl) or carbazole is meant respectively all the positional isomers of the two acid functions of the dicarboxylic acid of 2,5-diphenyloxazole, 1,4-bis(5-phenyloxazol-2-yl) or carbazole.

[0018] Thus, thanks to the implementation of the particular porous material of the MOF type which has just been described, the method according to the invention makes it possible not only to monitor the adsorption by this porous material of radioactive gases and, therefore, their storage within this porous material, but also to monitor the radioactive activity of these radioactive gases adsorbed and stored within this porous material by carrying out the online detection of the ionizing radiation from these radioactive gases. In particular, this monitoring of the activity of the adsorbed radioactive gases makes it possible to ensure that these radioactive gases remain trapped within the structure of the porous material. These monitorings of adsorption, storage and radioactive activity are ensured by monitoring the scintillation of the porous material.

[0019] As indicated above, the porous material used in the method according to the invention comprises metallo-organic networks formed of inorganic subunits linked together by organic ligands, the inorganic subunits being constituted by Zn4O and the organic ligands being chosen from - terephthalic acid, - 2,6-naphthalenedioic acid (or naphthalene-2,6-dicarboxylic acid), - 1,6-biphenyldioic acid (or biphenyl-2,6-dicarboxylic acid), - 9,10-anthracenedioic acid (or anthracene-9,10-dicarboxylic acid), - 2,7-pyrenedioic acid (or pyrene-2,7-dicarboxylic acid), - 1,8-terphenyldioic acid (or terphenyl-1,4-dicarboxylic acid), - 9,10-di(para-benzoic)-anthracene acid (A), - 2,5-bis-(para-benzoic)-1,3,4-oxadiazole acid (B), - a dicarboxylic derivative of 2,5-diphenyloxazole (C), - a dicarboxylic derivative of 1,4-bis(5-phenyloxazol-2-yl) (D), and - a dicarboxylic derivative of carbazole (E).

[0020] The porous material used in the method according to the invention is characterized by particular physicochemical and photophysical properties. This porous material has in particular the following properties: - a BET specific surface area of ​​between 50 m2 / g and 6000 m2 / g and, advantageously, of between 500 m2 / g and 6000 m2 / g, - an emission wavelength λem between 300 nm and 500 nm and, advantageously, between 380 nm and 500 nm, - a fluorescence quantum yield q> such that q> > 0.2 and, advantageously, such that q> > 0.5, - a fluorescence decline r between 1 ns and 1 ps, and - a LY scintillation efficiency greater than or equal to 3000 ph / MeV and, advantageously, between 4000 ph / MeV and 20000 ph / MeV.

[0021] In a variant of the method according to the invention, the porous material used in the method according to the invention is constituted by metallo-organic networks formed of inorganic subunits linked together by organic ligands, the inorganic subunits being constituted by Zn4O and the organic ligands being chosen from terephthalic acid, 2,6-naphthalenedioic acid, 1,6-biphenyldioic acid, 1,8-terphenyldioic acid, 9,10-anthracenedioic acid, 2,7-pyrenedioic acid, 9,10-di(para-benzoic)-anthracene acid, 2,5-bis-1,3,4-oxadiazole acid, a dicarboxylic derivative of 2,5-diphenyloxazole, a dicarboxylic derivative of 1,4-bis(5-phenyloxazol-2-yl) and a derivative dicarboxylic acid of carbazole.

[0022] When the organic ligands forming the metallo-organic networks of the porous material are constituted by terephthalic acid, the metallo-organic networks are advantageously MOFs known by the acronym IRMOF-1 or MOF-5.

[0023] When the organic ligands are constituted by 2,6-naphthalenedioic acid, the metallo-organic networks are advantageously MOFs known by the acronym IRMOF-8.

[0024] When the organic ligands are constituted by 1,6-biphenyldioic acid, the metallo-organic networks are advantageously chosen from the MOFs known by the acronyms IRMOF-9 and IRMOF-10, these two MOFs being characterized by two different structures due to concatenation.

[0025] When the organic ligands are constituted by 2,7-pyrenedioic acid, the metallo-organic networks are advantageously MOFs known by the acronym IRMOF-14.

[0026] When the organic ligands are constituted by 1,8-terphenyldioic acid, the metallo-organic networks are advantageously MOFs known by the acronym IRMOF-15 and IRMOF-16, these two MOFs being characterized by two different structures due to the concatenation.

[0027] When the organic ligands are constituted by 9,10-anthracenedioic acid, the metallo-organic networks are advantageously MOFs known by the acronym IRMOF-993.

[0028] When the organic ligands are constituted by 9,10-di(para-benzoic)-anthracene acid, the metallo-organic networks are advantageously MOFs known by the acronym IRMOF-A.

[0029] When the organic ligands are constituted by 2,5-bis-(para-benzoic)-1,3,4-oxadiazole acid, the metallo-organic networks are advantageously MOFs known by the acronym IRMOF-B.

[0030] When the organic ligands are constituted by a dicarboxylic derivative of 2,5-diphenyloxazole, the metallo-organic networks are advantageously MOFs known by the acronym IRMOF-C.

[0031] When the organic ligands are constituted by a dicarboxylic derivative of 1,4-bis(5-phenyloxazol-2-yl), the metallo-organic networks are advantageously MOFs known by the acronym IRMOF-D.

[0032] When the organic ligands are constituted by a dicarboxylic derivative of carbazole, the metallo-organic networks are advantageously MOFs known by the acronym IRMOF-E.

[0033] In an advantageous variant of the method according to the invention, the metallo-organic networks are chosen from IRMOF-1, IRMOF-8, IRMOF-9, IRMOF-10, IRMOF-14, IRMOF-15, IRMOF-16, IRMOF-993, IRMOF-A, IRMOF-B, IRMOF-C, IRMOF-D and IRMOF-E.

[0034] In another advantageous variant, the method according to the invention comprises, prior to step (a), a step (a0) consisting of bringing the porous material into contact with a humid atmosphere.

[0035] This humid atmosphere may in particular be an atmosphere having a relative humidity of between 20% and 95% and, advantageously, of between 60% and 90%, this atmosphere being at a temperature of between 15°C and 40°C and, advantageously, of between 20°C and 30°C.

[0036] In one variant, the porous material is brought into contact with the humid atmosphere. for a period of between 10 hours and 48 hours, advantageously between 24 hours and 36 hours.

[0037] In a more particularly advantageous variant of the method according to the invention, the metallo-organic networks of the porous material are formed by hydrated IRMOF-9.

[0038] In a variant, during step (b), the pressure of the radioactive gas in the enclosure is between 700 hPa and 10000 hPa, advantageously between 800 hPa and 2000 hPa and, preferably, between 850 hPa and 1100 hPa.

[0039] In a variant, during step (e), the vacuum pressure in the enclosure is between 109 hPa and 1 hPa and, advantageously, between 106 hPa and 102 hPa.

[0040] In a more particularly advantageous variant of the method according to the invention, the monitoring of steps (c) and (f) is carried out by detecting and counting the scintillation photons resulting from the scintillation of the porous material by the triple to double coincidence ratio (TDCR) method.

[0041] This method, which requires the implementation of a scintillation counter comprising three photomultipliers, makes it possible to acquire the average number of triple and double coincidences. The detection efficiency is calculated from the ratio of these coincidences. Thanks to this method, each observed photon is assigned to an event and not to the proper movement of the detectors (background noise).

[0042] The invention relates, secondly, to an installation for controlling the storage and radioactive activity of a radioactive gas adsorbed by a porous material.

[0043] According to the invention, this installation comprises: - an enclosure configured to contain the porous material, - a radioactive gas circulation system configured to circulate the radioactive gas within the enclosure, - a vacuum system configured to vacuum the enclosure, - a scintillation detection system configured to monitor the adsorption of the radioactive gas by the porous material and to monitor the radioactive activity of the radioactive gas adsorbed by the porous material, and - the porous material,

[0044] this porous material having scintillation properties and comprising metallo-organic networks formed of inorganic subunits linked together by organic ligands, the inorganic subunits being constituted by Zn4O and the organic ligands being chosen from terephthalic acid, 2,6-naphthalenedioic acid, 1,6-biphenyldioic acid, 1,8-terphenyldioic acid, 9,10-anthracenedioic acid, 2,7-pyrenedioic acid, 9,10-di(para-benzoic)-anthracene acid, 2,5-bis-(para-benzoic)-1,3,4-oxadiazole acid, a dicarboxylic derivative of 2,5-diphenyloxazole, a dicarboxylic derivative of l,4-bis(5-phenyloxazol-2-yl) and a dicarboxylic derivative of carbazole.

[0045] This installation, which operates in a closed circuit and which allows in particular the circulation of radioactive gases as well as the counting of photons, is more particularly adapted to the implementation of the method for controlling storage and radioactive activity described above. In other words, steps (a) to (f) of this method can be implemented within this installation according to the invention.

[0046] Thus, the installation according to the invention makes it possible to control by scintillation, by direct and online measurement, both the storage of radioactive gases in the porous material and the radioactive activity of the gases thus stored.

[0047] Preferably, the enclosure of the installation is impervious to external light, in particular to wavelengths between 200 nm and 800 nm. In other words, the enclosure of the installation isolates its contents from external light.

[0048] The scintillation detection system of the installation according to the invention can be chosen from: - a metrological system comprising an RCTD detection device comprising three photomultipliers and allowing the implementation of the triple to double coincidence ratio (RCTD) method, - a detection system a and / or [3 comprising two photomultipliers coupled to the enclosure, - a measurement system y, and - a coincidence measuring system [3 / y or a / y comprising either an RCTD detection device comprising three photomultipliers and a y detector, or a detection device with two photomultipliers and a y detector.

[0049] The invention relates, thirdly and fourthly, to a process for preparing a hydrated porous material from a porous material comprising metallo-organic networks formed from inorganic subunits constituted by Zn4O and linked together by organic ligands chosen from dicarboxylic acids as well as to the hydrated porous material as such.

[0050] According to the invention, the preparation process comprises: (i) contacting the porous material with an atmosphere having a relative humidity of between 20% and 95% and being at a temperature of between 15°C and 40°C, and (ii) recovery of the hydrated porous material,

[0051] the dicarboxylic acids being chosen from terephthalic acid, 2,6-naphthalenedioic acid, 1,6-biphenyldioic acid, 1,8-terphenyldioic acid, 9,10-anthracenedioic acid, 2,7-pyrenedioic acid, 9,10-di(para-benzoic)-anthracene acid, 2,5-bis-(para-benzoic)-1,3,4-oxadiazole acid, a dicarboxylic derivative of 2,5-diphenyloxazole, a dicarboxylic derivative of l,4-bis(5-phenyloxazol-2-yl) and a dicarboxylic derivative of carbazole.

[0052] In a variant, the contacting step (i) has a duration of between 10 h and 48 h.

[0053] The implementation of this method which comprises steps (i) and (ii) makes it possible to prepare a new porous material, in this case a hydrated porous material whose spectroscopic properties, and in particular the scintillation emission wavelengths, are modified compared to those presented by the porous material from which it is obtained.

[0054] Thus, the hydrated porous material according to the invention which, as has just been indicated, can in particular be obtained by the preparation process described above, is characterized by the following properties: - a BET specific surface area between 500 m2 / g and 6000 m2 / g, - an emission wavelength λem between 380 nm and 500 nm, - a fluorescence quantum yield q> such that q> > 0.5, - a fluorescence decay r between 1 ns and 1 ps, and - a scintillation yield LY between 3000 ph / MeV and 20000 ph / MeV.

[0055] Other characteristics and advantages of the invention will appear more clearly on reading the additional description which follows and which relates to the synthesis of two porous materials (IRMOF-9 and H-MOF) one of which (H-MOF) corresponds to the hydrated form of the other (IRMOF-9), to an installation making it possible to control the storage and radioactive activity of a radioactive gas adsorbed by the hydrated porous material as well as to the characterization of the latter.

[0056] It is specified that these examples, which are notably described in relation to the appended figures 1 to 7, are given only as an illustration of the objects of the invention and do not in any way constitute a limitation of these objects. Brief description of the drawings

[0057] [Fig. 1] is a schematic representation of the installation used for implementing the method for controlling the storage and radioactive activity of a radioactive gas adsorbed by the hydrated porous material H-MOF in accordance with the invention.

[0058] [Fig.2a] is a schematic representation of the enclosure of the installation partially shown in [Fig.l], enclosure in which the hydrated porous H-MOF material according to the invention is placed.

[0059] [Fig.2b] is a schematic representation of an enclosure that can be used instead of that shown in [Fig.2a].

[0060] [Fig.3] illustrates the normalized emission spectrum of the hydrated porous H-MOF material in accordance with the invention as a function of the emission wavelength (denoted kem and expressed in nm).

[0061] [Fig.4] illustrates the normalized fluorescence decline curve of the hydrated porous H-MOF material in accordance with the invention as a function of time (noted r and expressed in ns).

[0062] [Fig.5] illustrates the radioluminescence spectra as a function of the wavelength (denoted X and expressed in nm) of the hydrated porous H-MOF material in accordance with the invention, on the one hand, as well as the spectrum of a reference, on the other hand.

[0063] [Fig.6] shows the evolution of the counting rate (noted Tco and expressed in ^1) for the hydrated porous material H-MOF in the presence of radioactive gas as a function of the data acquisition date established between 01 / 10 / 2020 and 01 / 22 / 2020 (noted D).

[0064] [Fig.7] translates the evolution of the counting rate (noted Tc and expressed in s'1) for the hydrated porous H-MOF material impregnated with radioactive gas according to the data acquisition date established between 01 / 21 / 2020 and 01 / 22 / 2020 (noted D).

[0065] It is specified that the elements common to figures 1, 2a and 2b are identified by the same numerical references.

[0066] Detailed description of particular embodiments

[0067] 1. Synthesis of a porous material IRMOF-9

[0068] As seen previously, the porous material noted IRMOF-9 comprises metallo-organic networks formed of inorganic subunits constituted by Zn4O and linked together by organic ligands of 1,6-biphenyldioic acid.

[0069] This porous material IRMOF-9 is synthesized by dissolving 1.84 g (6.1 mmol) of zinc nitrate hexahydrate Zn(NO3)2-6H2O with 500 mg (2 mmol) of 1,6-biphenyldioic acid (BPDC) in 50 mL of A / A4dimethylformamide (DMF). The solution is then introduced into sealed pill bottles and placed in an oven at 80 °C for 4 days. The recovered crystals are washed three times with anhydrous DMF and then stored in an inert atmosphere in a glove box to prevent any possible degradation.

[0070] 2. Synthesis of a hydrated porous H-MOF material in accordance with the invention

[0071] The hydrated porous material in accordance with the invention is prepared from the porous material IRMOF-9 synthesized according to the protocol described in paragraph 1 above.

[0072] The IRMOF-9 crystals are placed in a climatic chamber at 25°C set at 80% relative humidity for a period of 24 hours at the end of which the hydrated crystals are removed from the chamber.

[0073] The product of the hydration of IRMOF-9, which corresponds to the hydrated porous material in accordance with the invention, is designated, in the remainder of this description, by the abbreviation H-MOF.

[0074] 3. Installation

[0075] In [Fig.l], there is shown schematically an installation 10 in accordance with the invention and used for implementing the storage and control method the radioactive activity of a gas adsorbed by the porous material exhibiting scintillation properties.

[0076] The installation 10 comprises an enclosure 12 configured to contain the porous material. This enclosure 12 may in particular be formed by a glass vial 12a as shown in [Fig.2a]. The porous material 14 or, where appropriate, the hydrated porous material 14' is placed in the center of the vial 12a.

[0077] The enclosure 12 may also be formed by a cartridge 12b as shown in [Fig.2b]. This cartridge 12b comprises a transparent cylindrical body 12c inside which the porous material 14 or the hydrated porous material 14' is placed. The cylindrical body 12c is provided at each of its ends with a sintered glass 12d allowing the passage of the radioactive gas 18. Such an enclosure 12b allows the radioactive gas 18 to pass through the entire porous material 14, 14' and, in doing so, to be independent of any diffusion dynamics.

[0078] The enclosure 12 is connected to a circulation system 16 for the gas 18, in this case the radioactive gas 18, configured to circulate the radioactive gas 18, from a reservoir 20, in the enclosure 12. This circulation system 16 comprises in particular a pump 22, a flow meter 26 and a filter 24. This filter 24 is typically a so-called "very high efficiency" or "THE" filter, which makes it possible to eliminate, if there is any, dust in the form of aerosol in the atmosphere loaded with radioactive gas 18.

[0079] The implementation of gas 18, which may in particular have a radioactive activity of between 10 mBq.m3 and 200 MBq.m\ being restrictive, this circulation system 16 must be reliably controlled, in particular by operating in a closed circuit and under controlled pressure.

[0080] The installation 10 according to the invention further comprises a vacuum system (not shown in [Fig.l]) which is configured to vacuum the enclosure 12 as well as a scintillation detection system 28.

[0081] This scintillation detection system 28 is configured for monitoring the adsorption of the radioactive gas 18 by the porous material 14 and for monitoring the radioactive activity of the radioactive gas 18 adsorbed by the porous material 14. This detection system 28, which allows the direct measurement of the photons resulting from the scintillation process, can also constitute an external detection path allowing the detection of the y radiation emitted by certain isotopes of radioactive gas 18.

[0082] 4. Characterization of the hydrated porous material H-MOF

[0083] 4.1 The hydrated porous material according to the invention H-MOF was first studied by photoluminescence using a spectrofluorimeter.

[0084] The normalized emission spectrum obtained for H-MOF, which reflects the evolution of the normalized intensity noted Inorm as a function of the emission wavelength Xem after excitation at an excitation wavelength of 360 nm, is represented on the [Fig.3]. We observe that the profile of this emission spectrum is close to a Gaussian curve centered on an emission wavelength Xmaxem of 460 nm. The measurement of the fluorescence quantum yield q> carried out gives a value of q> of the order of 0.75.

[0085] For comparison, these same values ​​measured for the IRMOF-9 respectively give an emission wavelength Xmaxem of 350 nm and a fluorescence quantum yield q> of 0.2.

[0086] [Fig.4] represents the normalized fluorescence decay curve, or fluorescence lifetime curve, of the emission observed at 460 nm. This curve, which reflects the evolution of the normalized intensity noted Inorm as a function of time r in ns, is fitted using a mono-exponential curve and makes it possible to approach a fluorescence lifetime value r of 40 ns.

[0087] The photoluminescence study therefore makes it possible to observe a shift in the emission wavelength Xem, an increase in the fluorescence quantum yield q> and an extension of the fluorescence lifetime r of the hydrated porous material according to the H-MOF invention compared to IRMOF-9.

[0088] 4.2 To evaluate the effectiveness of the hydrated porous H-MOF material according to the invention as a scintillator, a radioluminescence experiment was then carried out.

[0089] A sample of hydrated porous H-MOF material was placed in front of a photomultiplier equipped with an adjustable monochromator while a solid radioactive source was placed behind the sample for excitation. Photon collection is then carried out.

[0090] The radioluminescence spectrum obtained for the hydrated porous material H-MOF is illustrated in [Fig.5] by the curve denoted H-MOF.

[0091] By calculating the effect under this H-MOF curve and comparing it to the effect calculated under the reference curve measured at 7000 ph / MeV and noted Ref on this same [Fig.5], it is possible to go back to a LY scintillation efficiency of the order of 4500 ph / MeV.

[0092] The values ​​of the photophysical properties characterizing the hydrated porous H-MOF material in accordance with the invention are collated in Table 1 below.

[0093] [Tables 1] Properties Invention H-MOF IRMOF-9 Emission wavelength Xem (nm) 300 - 500 460 350 Fluorescence quantum yield 9 >0.2 0.75 0.2 Fluorescence decay r (ns) 1 - 1000 40 3.7 (92%) 16 (8%) Scintillation yield LY (ph / MeV) > 3000 4500 (unmeasured)

[0094] It is therefore observed that the hydration of IRMOF-9 makes it possible to obtain a new porous material, H-MOF, which is characterized by new properties, in particular by particularly interesting photophysical properties which will be used in the gas adsorption and retention tests, on the one hand, and scintillation and radioactive activity measurement, on the other hand, which are reported below.

[0095] 5. Performance of H-MOF material

[0096] To evaluate the performance in terms of storage and radioactive activity of the hydrated porous H-MOF material, the hydrated porous H-MOF material according to the invention was integrated into the vial 12a of the installation 10 equipped with a metrological system comprising an RCTD detection device provided with three photomultipliers making it possible to acquire the average number of triple and double coincidences by the triple to double coincidence ratio method (RCTD method) as a scintillation detection system 28.

[0097] This detection system 28 makes it possible to acquire the average number of triple and double coincidences, allowing the calculation of the detection efficiency from the ratio of these coincidences. It can be used in a dynamic or stationary mode.

[0098] In the dynamic mode, the counting rate monitoring is done in the presence of radioactive gas. The hydrated porous H-MOF material adsorbs the gas. The ionizing radiation then excites said material and allows the production of photons (depending on the radioactive source and its activity within the material). It is then possible to monitor the incorporation of radioactive gas into the material by scintillation. The detection system 28 then serves as a detector.

[0099] In the stationary mode, the H-MOF hydrated porous material is already impregnated with radioactive gas and retains it within itself. The H-MOF hydrated porous material is then placed in front of the photomultipliers to estimate a counting rate allowing an activity to be traced. It is then possible to use the H-MOF hydrated porous material as a storage entity capable of giving an estimate of the activity in function of the scintillation counting rate (x counts per second equal to y Bq). The detection system 28 then serves as a gauge.

[0100] 5.1 Gas adsorption and retention test (storage)

[0101] The ionizing gas is first circulated in the absence of porous material in the vial 12a to acquire the proper movement of the detection system 28 (also called background noise).

[0102] 150 mg of hydrated porous material H-MOF are then inserted into vial 12a but in the absence of ionizing gas to acquire a second blank.

[0103] These two acquisitions show a negligible counting rate. The first is zero while the second is 0.5 s1. This very slight increase is essentially due to the interaction of external radiation passing through the measuring device and depositing a little energy in the H-MOF.

[0104] 85Kr radioactive gas with an activity of 10 kBq is then circulated in the circulation system 16 at a pressure of 890 hPa and at a temperature of 20°C, which represents a volume activity of approximately 50 Bq.cm3.

[0105] As illustrated in [Fig.6], the acquisition reveals a clear increase in the counting rate over time with saturation being reached for a counting rate of 10000 counts / s.

[0106] This trend is indicative of adsorption and concentration of radioactive gas within the hydrated porous H-MOF material. This is experimental evidence of dynamic scintillation detection.

[0107] 5.2 Radioactive activity test

[0108] The circulation of the radioactive gas 85Kr with activity 10 kBq is then cut off and a primary vacuum of 103 hPa is applied in the flask 12a.

[0109] As illustrated in [Fig.7], the curve illustrating the counting rate does not allow a clear inflection to be highlighted.

[0110] This is experimental proof of the retention, and therefore of the storage, of the radioactive gas 85 Kr within the hydrated porous material H-MOF according to the invention, under primary vacuum and of its monitoring by direct measurement. In other words, it is possible to evaluate the quantity of radioactive gas in the hydrated porous material H-MOF precisely and, therefore, the radioactive activity of said material.

[0111] In view of the above, the hydrated porous material in accordance with the invention, such as the H-MOF material which has just been studied, is a material which has adsorption, storage and fluorescence properties and which, placed within an installation equipped with a detection system capable of counting photons, makes it possible to precisely determine the quantity of radioactive gas adsorbed and to verify its stability over time.

[0112] The method for controlling the storage and radioactive activity of a radioactive gas according to the invention, the installation according to the invention as well as the hydrated porous material according to the invention can in particular find application in one of the following fields: - for monitoring the activity of 3H and 85Kr releases from nuclear power plants and radioactive waste treatment plants; - for the storage of radioactive gases with active monitoring of the level and their containment; - in the field of radiation protection, for example for measuring the volume activity of radon in the air; - in the field of underground nuclear explosion detection, by measuring the volume activity of xenon or 37Ar isotopes; and / or - in the field of monitoring seismic activity and greenhouse gas emissions, by measuring the volume activity of radon in the air. Bibliography

[0113] US 7,985,868 B1

Claims

1.

2.

3. Claims Process for preparing a hydrated porous material (14') from a porous material (14) comprising metallo-organic networks formed from inorganic subunits constituted by Zn4O and linked together by organic ligands chosen from dicarboxylic acids, which process comprises: (i) contacting the porous material (14) with an atmosphere having a relative humidity of between 20% and 95% and being at a temperature of between 15°C and 40°C, and (ii) recovering the hydrated porous material (14'), the dicarboxylic acids being selected from 2,6-naphthalenedioic acid, 1,6-biphenyldioic acid, 1,8-terphenyldioic acid, 9,10-anthracenedioic acid, 2,7-pyrenedioic acid, 9,10-di(para-benzoic)-anthracene acid, 2,5-bis-(para-benzoic)-1,3,4-oxadiazole acid, a dicarboxylic derivative of 2,5-diphenyloxazole, a dicarboxylic derivative of 1,4-bis(5-phenyloxazol-2-yl) and a dicarboxylic derivative of carbazole. Preparation process according to claim 1, in which the porous material (14) is constituted by metallo-organic networks formed of inorganic subunits constituted by Zn4O and linked together by organic ligands chosen from 2,6-naphthalenedioic acid, 1,6-biphenyldioic acid, 1,8-terphenyldioic acid, 9,10-anthracenedioic acid, 2,7-pyrenedioic acid, 9,10-di(para-benzoic)-anthracene, 2,5-bis-(para-benzoic)-l,3,4-oxadiazole acid, a dicarboxylic derivative of 2,5-diphenyloxazole, a dicarboxylic derivative of 1,4-bis(5-phenyloxazol-2-yl) and a dicarboxylic derivative of carbazole. A preparation method according to claim 1 or 2, wherein the porous material (14) has the following properties: - a BET specific surface area of between 50 m2 / g and 6000 m2 / g and, advantageously, of between 500 m2 / g and 6000 m2 / g, - an emission wavelength Xem between 300 nm and 500 nm and, advantageously, between 380 nm and 500 nm, - a fluorescence quantum yield q> such that q> > 0.2 and, advantageously, such that q> > 0.5, - a fluorescence decline r between 1 ns and 1 ps, and - a LY scintillation efficiency greater than or equal to 3000 ph / MeV and, advantageously, between 3000 ph / MeV and 20000 ph / MeV.

4. A preparation process according to any one of claims 1 to 3, wherein the metal-organic frameworks are selected from IRMOF-8, IRMOF-9, IRMOF-10, IRMOF-14, IRMOF-15, IRMOF-16, IRMOF-993, IRMOF-A, IRMOF-B, IRMOF-C, IRMOF-D and IRMOF-E.

5. Preparation process according to any one of claims 1 to 4, in which step (i) of contacting has a duration of between 10 h and 48 h.

6. A hydrated porous material (14') prepared from a porous material (14) comprising metallo-organic networks formed from inorganic subunits constituted by Zn4O and bonded together by organic ligands selected from 2,6-naphthalenedioic acid, 1,6-biphenyldioic acid, 1,8-terphenyldioic acid, 9,10-anthracenedioic acid, 2,7-pyrenedioic acid, 9,10-di(para-benzoic)-anthracene acid, 2,5-bis-(para-benzoic)-1,3,4-oxadiazole acid, a dicarboxylic derivative of 2,5-diphenyloxazole, a dicarboxylic derivative of 1,4-bis(5-phenyloxazol-2-yl) and a dicarboxylic derivative of carbazole, this hydrated porous material (14') having the following properties: - a BET specific surface area of between 500 m2 / g and 6000 m2 / g, - an emission wavelength Xem of between 380 nm and 500 nm, - a fluorescence quantum yield q> such that q> > 0.5, - a fluorescence decay r of between 1 ns and 1 ps,and - a LY scintillation efficiency between 3000 ph / MeV and 20000 ph / MeV.,

7. The hydrated porous material (14') of claim 6, wherein the porous material (14) is constituted by metallo-organic networks formed of inorganic subunits constituted by Zn4O and linked together by organic ligands selected from 2,6-naphthalenedioic acid, 1,6-biphenyldioic acid, 1,8-terphenyldioic acid, 9,10-anthracenedioic acid, 2,7-pyrenedioic acid, 9,10-di(para-benzoic)-anthracene acid, 2,5-bis-(para-benzoic)-1,3,4-oxadiazole acid, a dicarboxylic derivative of 2,5-diphenyloxazole, a dicarboxylic derivative of 1,4-bis(5-phenyloxazol-2-yl) and a dicarboxylic derivative of carbazole.

8. A hydrated porous material (14') according to claim 6 or 7, wherein the porous material (14) has the following properties: - a BET specific surface area of between 50 m2 / g and 6000 m2 / g and, advantageously, of between 500 m2 / g and 6000 m2 / g, - an emission wavelength Xem of between 300 nm and 500 nm and, advantageously, of between 380 nm and 500 nm, - a fluorescence quantum yield q> such that q> > 0.2 and, advantageously, such that q> > 0.5, - a fluorescence decay r of between 1 ns and 1 ps, and - a LY scintillation efficiency greater than or equal to 3000 ph / MeV and, advantageously, between 3000 ph / MeV and 20000 ph / MeV.

9. A hydrated porous material (14') according to any one of claims 6 to 8, wherein the metal-organic networks are selected from IRMOF-8, IRMOF-9, IRMOF-10, IRMOF-14, IRMOF-15, IRMOF-16, IRMOF-993, IRMOF-A, IRMOF-B, IRMOF-C, IRMOF-D and IRMOF-E.

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