EP4096821A1

EP4096821A1 - Solid material having an open multiple porosity, comprising a geopolymer and solid particles, and method for the preparation thereof

Info

Publication number: EP4096821A1
Application number: EP21706349.4A
Authority: EP
Inventors: Alban GOSSARD; Agnès GRANDJEAN; David Lambertin; Nicolas FABREGUE
Original assignee: Commissariat a lEnergie Atomique CEA; Commissariat a lEnergie Atomique et aux Energies Alternatives CEA; Orano Recyclage SAS
Current assignee: Commissariat a lEnergie Atomique et aux Energies Alternatives CEA; Orano Recyclage SAS
Priority date: 2020-01-28
Filing date: 2021-01-25
Publication date: 2022-12-07
Also published as: US20230106358A1; JP2023513465A; FR3106507A1; FR3106507B1; WO2021152248A1; CN115379891A

Abstract

The invention relates to solid material which has an open multiple porosity and is at least partially interconnected, comprising an inorganic matrix made of a microporous and mesoporous geopolymer, in which at least partially interconnected open macropores are provided which are delimited by partitions or walls made of a microporous and mesoporous geopolymer, and comprising particles of at least one solid compound different from the geopolymer, which are distributed in the macropores and/or in the partitions or walls. A method for the preparation of said material is also disclosed. The invention also relates to a method for separating at least one metal or metalloid cation from a liquid medium containing same, wherein said liquid medium is brought into contact with said material.

Description

DESCRIPTION

Title: SOLID MATERIAL WITH MULTIPLE OPEN POROSITY CONSISTING OF A GEOPOLYMER AND SOLID PARTICLES AND ITS PREPARATION PROCESS

TECHNICAL AREA

The invention relates to a solid material with multiple open porosity, also called a material with hierarchical and open porosity, comprising a geopolymer and solid particles distributed in the porosity.

More specifically, the invention relates to a solid material, with open multiple porosity comprising an inorganic, mineral matrix, in a microporous and mesoporous geopolymer, in which are defined open macropores at least partially interconnected defined by walls or walls in geopolymer microporous and mesoporous inorganic, and particles of at least one solid compound distinct from the geopolymer being distributed in the macropores and / or in the walls or walls. The matrix can also be referred to as a “backbone”.

The particles can in particular be active particles, in particular particles of an inorganic solid compound exchanging a metal cation, particles of an adsorbent, or particles of a catalyst.

The material according to the invention can in particular be in the form of a monolith.

The invention also relates to the process for preparing said material.

The invention finds its application in many fields, such as the fields of catalysis, the separation of metal cations, or extraction on a solid phase by integrating particles of a selective adsorbent such as a zeolite. The invention finds its application more particularly in the field of the treatment of effluents, in particular of liquid effluents, and in particular of the treatment of radioactive liquid effluents, in particular with a view to removing metal cations therefrom, such as strontium cations. The present invention therefore also relates to a process for separating metal cations, in particular radioactive or toxic, contained in a medium, in particular a liquid medium, using said material.

STATE OF THE PRIOR ART

The processes using fixed beds require the development of materials with multiple porosity, to optimize the transport properties of the ions or molecules of interest, and of sufficient size to serve as a bed while limiting as much as possible the pressure drops. These materials with multiple porosity are in particular macroporous materials, and they comprise active sites constituted by nanometric, submicronic or micronic active particles in their porosity.

The preparation of these porous materials comprising nanometric, submicronic or micronic active particles in their porosity can, according to a first process, be carried out by granulation from nanometric, submicronic or micronic active particles obtained elsewhere and from an inorganic binder.

The whole is then cold compacted and the binder brings cohesion to the mixture of powders. The binder can be used dry for direct compression methods or in aqueous media for wet granulation processes. For the wet granulation process, the active nanometric, submicron or micron particles are suspended with the binder which will ensure cohesion, often followed by extrusion and heat treatment such as drying, or even sintering. The most commonly used inorganic binders are clay-based. This method is industrial and simple. It is also adaptable to all types of particles. However, it does not make it possible to obtain a controlled porosity of the material which then has poor transport properties (hydrodynamics and diffusion) for fixed bed applications. In addition, the "tablets" thus obtained have low mechanical strength [1].

The preparation of these porous materials comprising active nanometric, submicronic or micronic particles in their porosity can, according to a second process, be carried out by transformation of porous materials obtained elsewhere, for example porous silicas of silica gel type, porous glass, silicas obtained by the sol-gel route.

This second process consists in subjecting a chemical treatment to the support, the porosity of which is well controlled, in order to obtain the properties of the desired nanometric, submicron or micron particles [2-3].

This process is difficult to transpose to all types of active particles because each type of particle has a different composition, which therefore requires specific treatment. This process is complex and requires several steps, which therefore makes it difficult to transpose industrially. It can also lead to clogging of the porosity and therefore to poor accessibility to active sites.

The preparation of these porous materials comprising nanometric, submicronic or micronic active particles in their porosity can, according to a third process, be carried out by functionalization of porous materials. This process consists of pre-functionalizing a porous material playing the role of “backbone” and then growing an active material step by step [4-5] in the structure of the backbone from the pre-functionalized graft.

Here again, this process is complex, requires several steps, and is difficult to transpose to any type of particle. It can also lead to clogging of the pores.

The preparation of these porous materials comprising nanometric, submicron or micron active particles in their porosity can, according to a fourth process, be carried out by impregnation of a porous support material with a suspension containing the active nanometric, submicron or micron particles [6- 7].

This process is simple to implement but sometimes requires several impregnation steps. These impregnation steps are complex to manage because, on the one hand, they can lead to clogging of the pores of the porous support material and, on the other hand, they do not make it possible to perfectly control the quantity of particles inserted into the support, nor the homogeneity of the insertion of the particles into the network of pores. Finally, poor adhesion of the particles on the support is sometimes observed, which can lead to the release of the active particles when the material is used in operations for treating effluents in a fixed bed. In addition, this type of synthesis can lead to materials that are not very robust mechanically [6].

The preparation of these porous materials comprising nanometric, submicron or micron active particles in their porosity can, according to a fifth process, be carried out from oil-in-water emulsions comprising nanometric or submicronic active particles, the emulsion being stabilized. either by the presence of a surfactant, or by the active particles (Pickering type emulsion), or by a combination of the two. An inorganic oxide precursor in the aqueous phase makes it possible to bring consistency to the mixture by forming a backbone, once the oil phase has been extracted [8-9]. This process requires that the backbone is made up of an oxide (the vast majority of silica is used), which implies a synthesis of the sol-gel type which is complex to control, using relatively expensive precursors (alkoxides), and difficult to industrialize.

In addition, this process is limited to the insertion of active particles of small size (a few hundred nm at most), which may be difficult to synthesize for certain categories of active particles, and which may be difficult to manage industrially.

Finally, the alveolar porous structure of the materials obtained does not give them good hydrodynamic transport properties for fixed bed applications, which can make it difficult for the effluent to be treated to be accessible to some of the active particles incorporated into the backbone of the material. .

There therefore exists, in view of the above, an unmet need for a material with multiple porosity, in particular for a material with interconnected macroporosity which is mechanically robust and which can integrate active particles in a homogeneous manner, and so that these active particles are easily accessible to an effluent circulating in said macroporosity, in any case more accessible than in the materials of the prior art.

There is also a need for such a material which can have a wide variety of shapes and sizes, for example from a millimeter to several tens of centimeters.

A first object of the present invention is, inter alia, to meet such a need for such a material.

The aim of the present invention is also to provide such a material which does not have the defects, limitations and disadvantages of the materials of the prior art, in particular of the materials described in the documents of the prior art cited above, and which resolves the problems of these materials.

There is also a need for a process which makes it possible to prepare such a material, which is reliable, with a limited number of steps, which is versatile and which can be adapted to all kinds of active particles whatever their nature and their type. size (eg nanometric, micron or submicron). In particular, this method must be simple to implement in order to be reproducible and to be able to be easily transposed to an industrial scale.

A second aim of the present invention is, inter alia, to meet such a need for such a method.

DISCLOSURE OF THE INVENTION

The first object set out above, and others still, are achieved, according to the invention by a solid material with open multiple porosity and at least partially interconnected, comprising an (inorganic) matrix in a microporous and mesoporous geopolymer, in which are defined open macropores at least partially interconnected delimited by walls or walls of microporous and mesoporous geopolymer, and particles of at least one solid compound distinct from the geopolymer being distributed in the macropores and / or in the walls or walls. By “geopolymer” or “geopolymer matrix or skeleton” is meant in the context of the present invention a solid and porous material in the dry state, obtained following the hardening of a mixture containing finely ground materials (ie generally a source alumino-silicate) and a saline solution (ie an activation solution), said mixture being capable of setting and hardening over time. This mixture can also be designated under the terms “geopolymeric mixture”, “geopolymeric composition” or even “geopolymer paste”. The hardening of the geopolymer is the result of the dissolution / polycondensation of the finely ground materials of the geopolymeric mixture in a saline solution such as a saline solution of high pH (ie the activating solution).

More particularly, a geopolymer or geopolymer matrix or backbone is an amorphous alumino-silicate inorganic polymer. Said polymer is obtained from a reactive material essentially containing silica and aluminum (ie the alumino-silicate source), activated by a strongly alkaline solution (activation solution), the solid / solution mass ratio in the formulation being weak. The structure of a geopolymer is composed of an Si-O-Al network formed by tetrahedra of silicates (S1O ₄ ) and aluminates (AIO ₄ ) linked at their vertices by sharing oxygen atoms. Within this network, there are one or more charge-compensating cation (s) also called compensation cation (s) which compensate for the negative charge of the AIO ₄ complex. Said or said compensating cation (s) is (are) advantageously chosen from the group consisting of alkali metals such as lithium (Li), sodium (Na), potassium (K), rubidium (Rb ) and cesium (Cs), alkaline earth metals such as magnesium (Mg), calcium (Ca), strontium (Sr) and barium (Ba) and mixtures thereof.

The geopolymer as defined above is, according to the invention, macroporous, mesoporous and microporous, and it generally has a density of less than 1.5 g / cm ³ , in particular less than 1.2 g / cm ³ , in particular less than 0.9 g / cm ³ , and more particularly less than 0.6 g / cm ³ .

By “macroporous geopolymer” is meant a geopolymer having macropores; the term “mesoporous geopolymer” means a geopolymer exhibiting mesopores; and by “microporous geopolymer” is meant a geopolymer having micropores.

For the purposes of the present invention, the term “macropores” is understood to mean pores whose average dimension, generally defined by the diameter of their cross section - because the pores generally have a circular cross section -, greater than 500 A; The term “mesopores” is understood to mean pores the average size of which is from 20 to 500 Å; and the term “micropores” is understood to mean pores the average size of which is less than 20 Å, for example is 5 to 10 Å. Recall that nm = 10 Å.

The mesoporosity is typically between 20 and 33% by volume relative to the total porosity of the geopolymer.

The geopolymer forming the matrix, the backbone of the material according to the invention also comprises macropores defined in said backbone, said matrix.

The macroporosity is typically between 20 and 80% by volume relative to the total porosity of the geopolymer.

Porosity can be measured by adsorption-desorption of nitrogen or by intrusion of mercury.

The microporosity is typically less than 15% and in particular less than 10% and, in particular, between 5 and 10% by volume relative to the total porosity of the geopolymer.

In the geopolymer, the total porosity corresponding to the macroporosity, to the mesoporosity, and to the microporosity is greater than 70%, in particular greater than 75%, and, in particular, greater than 80% by volume relative to the total volume of the geopolymer .

The material according to the invention is a solid material with multiple porosity (namely with a macroporosity, a microporosity and a mesoporosity) open and at least partially or even totally interconnected also called material with open hierarchical porosity and at least partially or even totally interconnected.

More precisely, the material according to the invention has an open and connected (or interconnected) porosity. According to the invention, this porosity is multiple, that is to say it comprises both macroporosity, microporosity and mesoporosity.

This porosity is also open, that is to say accessible for a fluid such as an effluent brought into contact with the material. This porosity is also at least partly connected (or interconnected), or even totally interconnected, that is to say that the fluid can pass through the material passing through the pores connected to one another. This porosity also allows access to the particles.

The concept of open porosity applies to all pore sizes of the material, namely mesopores, micropores and mesopores. The pores (macropores, micropores and mesopores) are open and all at least partially connected, interconnected with each other, or even totally connected, interconnected with each other whatever their sizes.

Thus macropores can be connected with each other and with mesopores and / or micropores, mesopores can be connected with each other and with micropores and / or macropores, and micropores can be connected with each other and with macropores and / or mesopores.

It is not only the presence of micropores and mesopores that induces the opening and interconnection of macropores. Two macropores can be interconnected with each other.

To summarize, the interconnection of macropores is independent of the presence of mesopores and micropores.

Surprisingly, it has been observed that, due to the presence in the material according to the invention of particles, in particular active particles, the interconnection of the macropores was greatly improved compared to the same material but not comprising particles and that, moreover, the material according to the invention did not comprise partially closed alveolar macropores, on the contrary of the same material but without particles (see examples).

Advantageously, the geopolymer used in the context of the present invention has percolating macropores which connect a first main surface of the geopolymer material to a second main surface of the material). For the purposes of the present invention, the term “main surface” should be understood to mean an outer part of the material, which limits it with respect to its environment. The main surface (s) typically have cavities, in particular macroscopic, unobstructed.

The material according to the invention has a specific structure which has never been described or suggested in the prior art, and it is also constituted by specific materials, namely in particular a geopolymer which constitutes the backbone, the matrix of the material. according to the invention.

The material according to the invention further comprises particles of at least one solid compound distinct from the geopolymer, such as active particles, accessible in this matrix.

According to the invention, besides the simple presence of particles of at least one solid compound distinct from the geopolymer, such as active particles, it is important to choose the nature and size of the particles of at least one solid compound. distinct from the geopolymer almost without any limit and independently of the geopolymer matrix.

In fact, the material according to the invention can first of all be defined as a material with multiple porosity or with hierarchical porosity or even as a material with different scales of porosity, more precisely with three scales of porosity, with a matrix or skeleton. in which are defined open macropores at least partially interconnected (in other words an open macroporosity and at least partially interconnected) delimited by microporous and mesoporous walls or walls. The material according to the invention therefore comprises the combination of a macroporosity, a mesoporosity and a microporosity. In addition, in the material according to the invention, the macropores are open and at least partially interconnected, or even totally interconnected, and do not have a purely alveolar structure, and this is due, surprisingly, to the presence of particles of at least one solid compound distinct from the geopolymer in the material according to the invention.

In the material according to the invention, the open, interconnected macropores allow the transport of a fluid such as an effluent in the material, and the mesopores and micropores themselves open and interconnected ensure that the particles of at least one solid compound distinct from the geopolymer are easily accessible if these particles are found inside the walls, walls of the macropores.

In other words, the multiporosity and the interconnectivity between the macropores make it possible to very favorably optimize the transport of a fluid, such as an effluent within the material, and the accessibility to the particles.

It should be noted that a good interconnection can lead to good accessibility of the particles of at least one solid compound distinct from the geopolymer, but not systematically. We could thus have a strong interconnection of macropores but with particles entirely encrusted and agglomerated in the walls, walls. If the walls were neither mesoporous nor microporous, these particles would then be inaccessible and the material would not be satisfactory. In the material according to the invention, thanks to the open and interconnected micropores and mesopores, in particular with the macropores, good accessibility of the particles is always obtained.

The mechanical strength of the material according to the invention is ensured by the geopolymer skeleton (generally aluminosilicate) which is mechanically very robust.

Overall, a geopolymer matrix has many advantages over a metal oxide matrix.

The synthesis of a geopolymer is easier to control than the synthesis of a metal oxide by the sol-gel route.

The synthesis of a geopolymer requires precursors that are less expensive than those used to synthesize metal oxides (mainly alkoxides).

A geopolymer matrix has better mechanical strength than a metal oxide matrix.

A geopolymer matrix has mesopores, while a metal oxide matrix does not. To create mesoporosity in a metal oxide, it is necessary to add an additional compound in the formulation of the emulsion and therefore to make the system more complex.

Finally, in summary, the material according to the invention has a hierarchical porosity, is mechanically robust and integrates particles, generally particles. active particles (for example for a specific application in the context of the treatment of fluids such as liquid or gaseous effluents) with improved accessibility of the fluid such as an effluent to be treated to the particles distributed in the material due in particular to the interconnectivity that exists between macropores.

In other words, the material according to the invention has an open and interconnected macroporosity, with insertion of particles of at least one solid compound distinct from the geopolymer, and these particles are accessible.

Advantageously, the material according to the invention can be in the form of particles (these are not particles of at least one solid compound distinct from the geopolymer) such as grains, granules or beads; or in the form of a monolith.

The particles of material or the monolith can have a size (generally defined by their largest dimension, such as their diameter) of 300 microns (pm) to ten or several tens of cm, for example 10, 10, 30, 40, 50 or even 100 cm.

The term “size” is thus generally understood to mean the largest dimension of the particles of material or of the monolith.

A size of 300 to 500 microns is particularly suitable for use in a fixed bed by packing a column.

For the purposes of the present invention, the term “monolith” is understood to mean a solid object whose average size is at least 1 mm.

Advantageously, the particles of at least one solid compound distinct from the geopolymer can have an average size, such as a diameter, from 2 nm to 100 μm, preferably from 10 nm to 10 μm.

The term “size” is understood here also to mean the largest dimension of the particles of at least one solid compound distinct from the geopolymer, such as the diameter.

The particle size of at least one solid compound distinct from the geopolymer can be chosen for a specific intended application.

Advantageously, the particles of at least one solid compound distinct from the geopolymer can be chosen from the group consisting of nanometric particles, submicronic particles, and micron particles. For the purposes of the present invention, the term “nanometric particles” is understood to mean particles whose average size, generally defined by their diameter, is from 2 to 100 nm; The term “submicronic particles” is understood to mean particles whose average size, generally defined by their diameter, is from 100 nm to 1 μm; and the term “micron particles” is understood to mean particles whose average size, generally defined by their diameter, is from 1 to 100 μm.

The particles of at least one solid compound distinct from the geopolymer can be entirely inorganic, mineral particles, namely particles consisting only, solely (100%) of one or more solid inorganic compound (s).

The particles of at least one solid compound distinct from the geopolymer may be partially organic particles, namely particles comprising, in addition to one or more solid inorganic compound (s), one or more solid compound (s) (s) organic, this is the case in particular with particles of “MOFs” (see below).

Advantageously, the particles of at least one solid compound distinct from the geopolymer can be particles of an active compound, or more simply active particles.

By “active particles” or particles of an active compound, is generally meant (as opposed to inert particles) particles capable of acting in a chemical, physical or physicochemical process such as a chemical reaction, sorption phenomena. , catalytic processes etc., for example in catalysis or in extraction, for the treatment in particular of liquid or gaseous effluents.

Preferably, these active particles are chosen from the group consisting of the particles of at least one solid compound exchanging a metal cation, the particles of catalysts, and the particles of adsorbent compounds.

Advantageously, the solid compound exchanging a metal cation can be chosen from the group consisting of zeolites; alkaline silicotitanates; coordination polymer particles (“Metal-Organic Frameworks”), and mixtures thereof.

There is no limitation on the particle shape of at least one solid compound distinct from the geopolymer. Advantageously, the particles of at least one solid compound distinct from the geopolymer can have the shape of a sphere or of a spheroid, or else an acicular shape.

Advantageously, the particle content of at least one solid compound distinct from the geopolymer is from 0.1 to 30% by mass, preferably from 5 to 15% by mass of the total mass of the material.

The second object explained above is achieved, according to the invention, by a process for preparing the material according to the invention as described above.

This preparation process comprises at least the following successive steps: a) is prepared, by mechanical stirring with shear of a mixture comprising an oily phase and an aqueous phase, an oil-in-water emulsion formed of dispersed droplets of the oily phase in the continuous aqueous phase, the aqueous phase comprising an activation solution, an aluminosilicate source capable of forming a geopolymer by dissolution / polycondensation (of the aluminosilicate source in the activation solution) and optionally a surfactant, and particles of at least one solid compound (distinct from the geopolymer) being present at the interface formed by the continuous aqueous phase and the droplets of the oily phase dispersed in the continuous aqueous phase of the emulsion; b) the emulsion is allowed to stand, and it is shaped and shaped to obtain a chosen size and shape, and the geopolymer matrix is formed by polycondensation; c) the oily phase is removed, and the material according to the invention as described above is thus obtained. Advantageously, the emulsion is shaped and shaped in a mold of chosen size and shape.

The method according to the invention comprises a specific series of specific steps which has never been described or suggested in the prior art, as represented in particular by the documents cited above. The method according to the invention allows the synthesis, preparation, of the material according to the invention, that is to say of a material with hierarchical porosity, mechanically robust and integrating particles, in particular active particles (for example active particles which have a specific application in the context of the treatment of liquid or gaseous effluents), with improved accessibility of the particles, to the fluid such as an effluent to be treated.

The method according to the invention allows the synthesis of said material with a shape and a controlled size, ranging for example from a millimeter to several tens of centimeters (see above), and this without a mechanical step of grinding or compacting. subsequent to the synthesis.

Importantly, it should be noted that the process according to the invention allows the synthesis of the material without any limitation of any kind on the size and shape thereof.

Thus it is, for example, only the size of the mold which can be implemented during step b) which will limit the size of the final shaped material, in other words of the object constituted by the material.

The process according to the invention is characterized in particular by the use of the reagents necessary for the synthesis of an inorganic binder, based on a geopolymer, within the continuous phase of an emulsion comprising particles of at least one compound. solid distinct from the geopolymer, such as active particles.

The method of preparing the emulsion is, according to the invention, optimized in order in particular to allow better interconnectivity between the macropores of the geopolymer skeleton and therefore better accessibility of a fluid circulating in the material to the active particles.

According to the invention, in a new and unexpected manner, an emulsion having as continuous phase an aqueous activation solution of a geopolymer is stabilized using particles of at least one solid compound distinct from the geopolymer, such as active particles, and optionally a surfactant, as well as a protocol comprising at least one sequence, for example 2 homogenization sequences.

These last two parameters (namely, stabilization using particles, and possibly a surfactant, and a protocol comprising at least one homogenization sequence) allow the formation of pores, in particular macropores, which are non-alveolar and better interconnected allowing better access to active particles.

In other words, in the process according to the invention, during step a) an oil-in-water emulsion is prepared, more specifically an oily phase dispersed in a continuous aqueous phase, this aqueous phase comprising an activation solution, and an aluminosilicate source capable of forming the geopolymer by dissolution / polycondensation. This emulsion is stabilized in the presence of particles of at least one solid compound distinct from the geopolymer, in particular of active particles. The addition of a surfactant which can act synergistically with the particles to stabilize the emulsion is sometimes necessary.

The control of the parameters of this emulsion, and in particular the control of the size of the oil droplets, by the control of the various stages of the process (including stages a3) and a4) described below), makes it possible to control the final porosity of the material.

The insertion of an aluminosilicate source makes it possible to obtain an inorganic binder of geopolymer type in the aqueous phase of the emulsion by a dissolution-polycondensation process.

The emulsion prepared in step a) generally comprises 40% vol. at 80% vol., preferably 50% vol. at 60% vol. oily phase relative to the total volume of the emulsion.

The concentration of solid particles in the emulsion can be from 0.05% by mass to 20% by mass, preferably from 1% by mass to 10% by mass.

The oily phase of the mixture generally consists of one or more oil (s). The term “oil” is well known to those skilled in the art in this field of the art and widely used. The method according to the invention can be implemented successfully with any type of oil.

Advantageously, the oily phase of the mixture generally consists of one or more linear or branched alkanes having from 7 to 22 carbon atoms, preferably from 12 to 16 carbon atoms, such as dodecane and hexadecane.

Preferably, the oily phase of the mixture consists of dodecane.

The mechanical stirring carried out during step a) is mechanical stirring with shear.

Advantageously, the shearing speed can range from 1000 to 20,000 rev / min, preferably from 2000 to 15,000 rev / min, more preferably the shearing speed can be 10,000 rev / min.

It is possible to control the size of the macroporosity of the material by acting on the shear rate of the emulsion. The size of the macroporosity decreases as the shear rate increases.

The mechanical agitation with shearing (mechanical agitation goes hand in hand with the shearing) carried out during step a) can be carried out by different methods, each of these methods making it possible to obtain a particular porosity. Indeed, a higher shear rate will generate the formation of smaller macropores than for lower shear rates. Thus, the shearing of the emulsion may be mechanical shearing using a homogenizer, or shearing by sonication using ultrasound.

Preferably, the mechanical shear agitation performed during step a) is performed using an apparatus for emulsification apparatus such as a homogenizer disperseur- type Ultraturrax ^®. Step a) can be qualified as the step of emulsifying the mixture described above.

In other words, by mechanical stirring with shear is generally meant a mechanical stirring which uses a stirring device equipped with a blade rod or, preferably, a homogenization or dispersion device (for example of the Ultra-Turrax type, IKA ^® ) which can be fitted with a dispersion rod having a rotor / stator system. As already specified above, advantageously, the shear speed imposed by the homogenization or dispersion device can range from 1000 to 20,000 rev / min, preferably from 2000 to 15,000 rev / min, more preferably the shear speed can be 10,000 rpm.

The expression "aluminosilicate source" and the expression "reactive material essentially containing silica and aluminum" are, in the present invention, similar and usable interchangeably.

The reactive material essentially containing silica and aluminum which can be used to prepare the geopolymer matrix of the material according to the invention is advantageously a solid source containing amorphous aluminosilicates. These amorphous aluminosilicates are chosen in particular from natural aluminosilicate minerals such as illite, stilbite, kaolinite, pyrophyllite, andalusite, bentonite, kyanite, milanite, grovenite, amesite, cordierite, feldspar, allophane, etc. ; calcined natural aluminosilicate minerals such as metakaolin; synthetic glasses based on pure aluminosilicates; aluminous cement; pumice stone; calcined by-products or industrial exploitation residues such as fly ash and blast furnace slag respectively obtained from the combustion of coal and during the transformation of iron ore into cast iron in a blast furnace; and mixtures thereof.

The term “activation solution” is understood to mean the saline solution of high pH which is well known in the field of geopolymerization. The latter is a strongly alkaline aqueous solution which may optionally contain silicate components chosen in particular from the group consisting of silica, colloidal silica and vitreous silica.

The terms "activating solution", "high pH saline solution" and "strongly alkaline solution" are, in the present invention, similar and can be used interchangeably.

By “strongly alkaline” or “of high pH” is meant a solution whose pH is greater than 9, in particular greater than 10, in particular greater than 11 and more particularly greater than 12. In other words, the activation solution presents a OH concentration greater than 0.01 M, in particular greater than 0.1 M, in particular greater than 1 M and, more particularly, between 5 and 20 M.

The activation solution comprises the compensating cation or the mixture of compensating cations as defined above in the form of an ionic solution or of a salt. Thus, the activation solution is chosen in particular from an aqueous solution of sodium silicate (Na2SiO3), potassium silicate (K2S1O2), sodium hydroxide (NaOH), potassium hydroxide (KOH), calcium hydroxide (Ca (OH) 2), cesium hydroxide (CsOH) and their derivatives etc.

During step b), the emulsion is allowed to stand so that the geopolymer backbone can be formed by polycondensation in the continuous phase of the emulsion.

During this resting step, the size and shape of the final material are then defined by virtue of the workability of the emulsion synthesized.

Thus, depending on the workability of the emulsion, it is possible to obtain monoliths, beads or grains.

By "workability" is meant the ability of the emulsion to be shaped and shaped (using a mold for example) for a certain period of time before the hardening forming the final material, that is to say. that is to say when the emulsion has a still liquid, or even gelled, appearance before hardening and forming the material.

This step can be carried out by leaving the emulsion obtained in step b) to stand at a temperature of 10 to 60 ° C, for example at a temperature of 40 ° C for a period sufficient for the material according to the invention forms. This duration can be for example from 2 hours to 3 weeks, for example from 24 hours to 7 days.

During step c), the oily phase, still present in the pores of the material, is removed.

The oily phase can be removed by any technique known to those skilled in the art.

The oily phase can in particular be removed by washing, for example in a Soxhlet extractor, followed by drying, by treatment with a supercritical fluid, such as supercritical CO2, by a hydrothermal treatment, by a heat treatment, or by a combination of these different treatments. The washing makes it possible to eliminate the organic residues coming from the oily phase and which are mainly found in the macropores.

This washing can be carried out with an organic solvent such as THF, acetone and their mixtures, for example a THF-acetone mixture, preferably a 50-50 mixture of THF and acetone.

This washing can be carried out for a period of 12 to 36 hours, for example 24 hours.

Preferably, this washing is carried out by bringing the organic solvent to reflux.

Drying can be carried out by allowing the organic solvent used for washing to evaporate at room temperature for a period generally of 5 to 10 days, for example 7 days.

Or, the drying can be carried out with heating, for example at a temperature of 90 ° C.

Drying can also be performed using a supercritical fluid, such as supercritical CO2.

With the process according to the invention, the material according to the invention is obtained, namely a macroporous material (the macroporosity of which is generated by the oily phase), comprising particles, preferably active particles, in particular nanometric, submicron or micronic which are used in particular to stabilize the emulsion (but also for the desired application of the material), with the synergistic help or not of a surfactant. This controls both the porosity, the mechanical strength - conferred by the geopolymer skeleton of the material - the shape and size of the material, and the nature and size of the active sites.

This process is simple to implement, and easily transposable industrially.

In summary, the advantages and unexpected effects of the process according to the invention, for the manufacture and preparation of the material according to the invention, namely of a material with multiple porosity comprising active particles are, among others, listed below. Some of these advantages of the process are advantages linked to the material that this process makes it possible to obtain and which have for the most part already been explained above:

• Multiporosity and interconnectivity between macropores are totally controlled by controlling the emulsion (the size of the oil drops in particular), thus making it possible to optimize the transport properties of a fluid, such as an effluent. , within the material and the accessibility of the fluid to the active particles.

• The mesoporosity and microporosity of the geopolymer matrix ensure increased accessibility to the active particles that may be integrated into the heart of the walls, the walls of the material's macropores.

• The mechanical strength of the final material is ensured by the robust aluminosilicate geopolymer skeleton.

• It is extremely important to note that, the method according to the invention can be implemented, with any type of particle, in particular of active particle, whatever its nature, its size, in particular from 2 nm to 100 μm, from preferably from 10 nm to 10 μm, and its particle size distribution, which can be nanometric as well as submicron or even micron.

For this, it is only necessary to adapt the parameters for obtaining and stabilizing the starting emulsion.

• The size of the active sites corresponds directly to the size of the particles integrated into the formulation of the material of the invention (nanometric, submicron or micron) and which are obtained elsewhere.

• The size of the final shaped material obtained is completely flexible and depends, for example, on the mold in which step b) takes place.

• The process according to the invention is carried out under mild conditions, at low temperatures, generally at room temperature and at atmospheric pressure.

The method according to the invention uses inexpensive and non-toxic reagents, in particular for the activation solution and the aluminosilicate source. The reaction media are essentially aqueous.

• The method according to the invention is simple, reliable, and easy to implement, it uses reagents that are readily available and at low cost. It can be achieved with simple installation and equipment. In particular, the process according to the invention is a process in which all of the stages (including stages a3) and a4) described below) can be carried out in a single reactor. In other words, the process according to the invention can be qualified as a “one-pot” process.

Thus, step b) can be carried out in a reactor, a single vessel which is the same reactor as that used during step a) if the vessel, reactor, used to produce the emulsion during step a) is used as a mold subsequently, during step b) and step c).

• The method according to the invention is easily transposable to an industrial scale.

Advantageously, prior to step a), the following successive sub-steps a1) to a4) are carried out in order to prepare the mixture comprising an oily phase and an aqueous phase: a1) an aqueous suspension of particles, preferably of active particles, of at least one solid compound (other than the geopolymer), in water or in an aqueous solution comprising a surfactant; a2) an oily phase is added to the aqueous suspension of particles obtained at the end of step al) whereby a two-phase mixture is obtained comprising the oily phase and an aqueous phase consisting of the aqueous suspension; a3) an aqueous activating solution (alkali silicate) is added to the aqueous phase of the two-phase mixture obtained at the end of step a2); a4) an aluminosilicate source capable of forming the geopolymer by dissolution / polycondensation is added to the aqueous phase of the two-phase mixture obtained at the end of step a3). Generally, the aqueous suspension of particles prepared in step a1) has a particle concentration of 2 g / L to 1000 g / L.

The concentration of particles in the suspension is chosen as a function of the final concentration of particles of at least one solid compound distinct from the geopolymer desired in the material prepared.

The surfactant can be chosen from anionic, cationic and nonionic surfactants, and mixtures thereof. An example of a surfactant is Tetradecyltrimethylammonium Bromide (“Tetradecyltrimethylammonium bromide” or TTAB in English).

The surfactant concentration in the aqueous suspension prepared in step a1) is generally 0.1% to 20% by mass relative to the mass of the particles.

Advantageously, at the end of step a2), and before step a3), the two-phase mixture comprising the oily phase and an aqueous phase consisting of the aqueous suspension is subjected to mechanical stirring with shear; and / or at the end of step a3) and before step a4), the two-phase mixture is subjected to mechanical stirring with shear.

This mechanical agitation with shear has already been described in detail above.

The invention also relates to the use of the material according to the invention for catalyzing chemical reactions, for the filtration of a fluid, or for the separation or extraction of substances contained in a fluid. This fluid can be in any physical state, in particular liquid or gas.

The material according to the invention can be used in particular, but not exclusively, in a process for separating at least one metal or metalloid cation from a liquid medium containing it, in which said liquid medium is brought into contact. with the material according to the invention.

This medium can be liquid or gaseous.

The materials according to the invention, on account of their excellent properties such as excellent exchange capacity, excellent selectivity and high reaction rate, are particularly suitable for such use. This excellent efficiency is obtained with reduced amounts of active particles, for example particles of an inorganic solid compound exchanging a metal cation such as a zeolite.

In addition, the excellent mechanical strength and stability properties of the material according to the invention, resulting from its specific structure, allow its packaging in a column and the continuous implementation of the separation process, which can thus be easily integrated into an installation. existing, for example in a chain or processing line comprising several steps.

Advantageously, said liquid medium can be an aqueous liquid medium, such as an aqueous solution.

Said liquid medium may be a process liquid or an industrial effluent.

Advantageously, said liquid medium can be chosen from liquids and effluents from industry and nuclear installations and from activities using radionuclides.

Generally, said cation can be present at a concentration of 0.1 picogram to 500 mg / L, preferably 0.1 picogram to 100 mg / L.

The term “metal” also covers isotopes and in particular radioactive isotopes of said metal, and the term “metalloid” also covers isotopes and in particular radioactive isotopes of said metalloid.

Advantageously, the cation can be a cation of an element chosen from alkali metals, alkaline earth metals, transition metals, heavy metals, rare earths (scandium, yttrium and lanthanides), actinides, rare gases. , and isotopes, in particular radioactive, thereof.

Zeolites are particularly well suited to the separation of such cations.

For example, the cation can be a cation of an element selected from Sr, Cs, Co, Ag, Ru, Fe and Tl and isotopes, especially radioactive isotopes thereof.

In particular, the cation may be a cation of ¹³⁴ Cs, or ¹³⁷ Cs, or ⁹⁰ Sr.

This method has all the advantages intrinsically linked to the material according to the invention, implemented in this method, and which have already been described above. The invention will now be described in more detail in what follows, in particular in conjunction with particular embodiments thereof which are the subject of examples.

BRIEF DESCRIPTION OF THE DRAWINGS

[Fig. 1] is a photograph taken with a Scanning Electron Microscope (SEM) of the submicron particles of LTA zeolite prepared in Example 1.

The scale shown in Figure 1 represents 1 µm.

[Fig. 2] is a photograph of the monolith, comprising a geopolymer integrating submicron particles of LTA zeolite, prepared in Example 1 using the PO protocol.

[Fig. 3A] and

[Fig. 3B] show images taken with SEM of the interior of the monoliths prepared in Example 1 and in Example IA respectively.

The scale shown in Figures 3A and 3B represents 70 µm.

[Fig. 4] is a graph which shows the pore size distribution in a pure synthesized geopolymer (Example IB) (curve A), and in two geopolymers synthesized by PO with zeolite (Example 1) (curve B), and by PO without zeolite (Example IA) (curve C).

On the abscissa is plotted the pore diameter (in nm) and on the ordinate is plotted dV / dlog (D) Pore volume (in cm ³ / g-nm).

[Fig. 5] is a graph which shows the diffractograms of the submicron LTA zeolite (curve A), of a geopolymer without zeolite synthesized by PO (Example IA) (curve B) and of a geopolymer including LTA zeolite synthesized by PO ( Example 1) (curve C).

On the x-axis is plotted 2 theta (in °) and on the y-axis is plotted the intensity (in arbitrary units).

[Fig. 6A]

[Fig. 6B] and [Fig. 6C] show images taken with SEM of the geopolymer monoliths prepared in Example 2, according to the PI protocol (FIG. 6A), the P2 protocol (FIG. 6B) and the P3 protocol (FIG. 6C).

The scale shown in Figures 6A, 6B and 6C represents 70 µm.

[Fig. 7] is a graph which shows the pore size distribution in the monoliths prepared in Example 2 by the P1, P2 and P3 protocols.

[Fig. 8] is a bar graph which shows the values of Kd (in mL / g) (example 3) determined for a geopolymer monolith (without submicron zeolite particles) prepared according to the PO protocol, and for geopolymer monoliths , (comprising zeolite particles) prepared according to the PO, PI, P2 and P3 protocols. [Fig. 9] is an SEM image of the micronic zeolite particles used in Example 4.

The scale shown in Figure 9 represents 5 µm.

[Fig. 10] is a graph which shows the diffractograms (example 4B) of the micron 4A zeolite particles (curve A), of a geopolymer without 4A zeolite particles prepared according to the protocol P3 (curve B), and of a geopolymer including 4A zeolite particles prepared according to protocol P3 (curve C).

[Fig. 11] is a graph which shows the particle size analysis of the size of the nanometric CST particles used in Example 5.

On the x-axis is the size (in pm), and on the y-axis is the% (in number).

[Fig. 12] is a graph which shows the diffractograms (Example 5B) of CST nanoparticles (curve A), of a geopolymer without CST prepared according to protocol P3 (curve B) and of a geopolymer including CST nanoparticles prepared according to the protocol P3 (curve C). [Fig. 13] is a graph which shows the nitrogen adsorption isotherm carried out on the pure geopolymer. The relative pressure (P / P °) is plotted on the abscissa, and the quantity of nitrogen adsorbed (in cm ³ / g) on the ordinate.

DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS

The invention will now be described with reference to the following examples, given by way of illustration and not by way of limitation.

Examples-

Example 1:

In this example, one proceeds to the manufacture, in accordance with the invention, of a monolithic material comprising a geopolymer incorporating a submicron zeolite.

More exactly, in this example, in accordance with the invention, submicron particles of LTA zeolite (known to be an effective and selective adsorbent for Sr in an aqueous medium) are integrated within a “backbone” matrix of macroporous geopolymer.

• Synthesis of submicron particles of LTA zeolite.

The protocol for the synthesis of submicron particles of LTA zeolite is as follows:

2.65 g of NaOH pellets (commercially available from Sigma-Aldrich ^®), and 5.75 g of powder NaAIÜ2 (sold by VWR ^®) are separately dissolved respectively in 26.25 mL and 35 mL of water.

The two solutions are then mixed in an autoclave with vigorous stirring for a few minutes.

Then 2 g of powder of S1O2 (Aerosil ^® 380 available from Evonik Industries ^®) into the autoclave, and the autoclave is closed hermetically. A heat treatment at 40 ° C for 20 h, then at 70 ° C for 24 h, is applied.

The powder obtained is finally recovered by filtration, washed with water, and dried overnight at 80 ° C.

Finally, submicron particles of LTA zeolite with a size of between 300 and 500 nm are obtained (see FIG. 1).

• Manufacture of the material in the form of a monolith, comprising a geopolymer incorporating the submicron particles of LTA zeolite.

The protocol for the synthesis of the material comprising a geopolymer integrating the submicron particles of LTA zeolite synthesized as described above is the following protocol which is called the PO protocol and which first of all comprises the successive steps:

Step 1: 617 mg of LTA zeolite powder (consisting of submicronic particles) are added to 1.774 mL of an aqueous solution concentrated at 34.8 gL ¹ in surfactant, namely tetradecyltrimethylammonium bromide (“Tetradecyltrimethylammonium bromide” or TTAB in English) (marketed by Sigma-Aldrich ^® ). The concentrated aqueous solution to which the powder has been added is placed for 15 minutes in an ultrasonic bath.

Step 2: Addition, to the concentrated aqueous solution in which the powder was added 5 mL of oil phase, namely dodecane (commercially available from Sigma-Aldrich ^®).

Step 3: Addition of 2.12 ml of a solution composed of 81% by mass of a commercial inorganic binder referred Betol K5020T ^® (available from the company Wollner ^®) based on an aqueous potassium silicate solution amended, and composed of S1O2 at 30% by mass, K2O at 18% by mass, and H2O at 52% by mass; and 19 wt% KOH (85%, commercially available from Sigma-Aldrich ^®).

Step 4: Addition of 2.64 g of Metakaolin powder (Métamax ^® from BASF)

Step 5, known as step “UT”: the mixture is finally sheared for 1 minute using an Ultra-Turrax ^® homogenizer equipped with an S25N-18G dispersion head at a shearing speed of 10,000 revolutions / min. An emulsion is thus obtained at the end of step 5.

This viscous emulsion is placed in a cylindrical mold one cm in diameter which is left to stand for 48 h.

After demoulding, a solid monolithic cylindrical material is obtained about 4 cm in height and 1 cm in diameter.

This monolithic material is then washed in the Soxhlet extractor with a 50-50 mixture of THF-acetone to remove the dodecane, then is left to dry at 80 ° C.

After 24 h of drying, the massive and robust monolith, having retained its dimensions, is obtained (Figure 2).

Example IA.

In this example, a material is produced in the form of a monolith similar to that of Example 1, but not comprising submicron particles of LTA zeolite. This monolith is synthesized according to the same protocol, called the PO protocol, as in Example 1.

Example IB.

In this example, a pure geopolymer is produced (pure synthesized geopolymer), that is to say according to the PO protocol, but without submicron zeolite, without TTAB, and without adding oil to form an emulsion.

The geopolymer obtained has a specific surface area of 71.3 m ² .g ^_1 .

Example IC.

In this example, the characterization of the materials prepared in Examples 1, IA, and IB is carried out.

• The interior of the two monoliths prepared in Example 1 and in Example IA is observed by scanning electron microscopy (SEM).

The images obtained are shown in Figures 3A and 3B.

We observe that: In the absence of zeolite particles, the material has alveolar pores that are not (or very little) interconnected.

In the presence of zeolite, the microstructure of the material is completely different. The pores no longer have an alveolar structure and their interconnection is improved.

The monoliths prepared in Examples 1 and IA are analyzed by adsorption-desorption of nitrogen in order to determine the specific surface (BET model) and the pore size distribution (<60 nm, BJH model).

Specific surfaces of 34.4 and 37.8 ir ^ .g ¹ are measured for the geopolymers respectively with (material of example 1) and without zeolite (material of example IA).

Figure 4 shows the size distributions of mesopores in the two materials.

Also shown in this figure is the size distribution of mesopores of the pure geopolymer, prepared in Example IB.

It is observed that the pure synthesized geopolymer (Example IB) and the material prepared using the PO protocol without zeolite (Example IA) exhibit pore size distributions centered around 19-20 nm, while the material synthesized using the protocol PO with zeolite (Example 1 in accordance with the invention) has a pore size distribution rather centered around 27 nm.

The presence of zeolite in the formulation is thus likely to increase the size of the mesopores.

Figure 13 shows the adsorption isotherm of the pure geopolymer. This isotherm presents a type IV appearance in the IUPAC classification and demonstrates the presence of micropores in the structure of the geopolymer by the shape of the curve at low pressures.

The two monoliths prepared in Example 1 and in Example IA are then ground in powder form and then an X-ray diffraction (XRD) analysis is carried out. A DRX analysis is also carried out on the pure submicronic LTA zeolite powder.

The results of these analyzes are shown in Figure 5.

(NB: in Figure 5, it is mentioned "pure geopolymer": it is the geopolymer synthesized without submicron zeolite, without TTAB and without having added oil to form an emulsion (geopolymer of example IB)).

The 3 diffractograms presented in FIG. 5 demonstrate that the submicron particles of LTA zeolite have, in the material prepared in Example 1, in accordance with the invention, indeed been integrated into the structure of the macroporous geopolymer.

Example 1D.

In this example, the effectiveness of the material prepared in Example 1 in accordance with the invention, and of the material prepared in Example IA for the decontamination of effluents containing Strontium (Sr) is studied.

In other words, in this example, the material prepared in Example 1 in accordance with the invention is tested, and the material prepared in Example IA in the context of an application as an adsorbent material for Sr.

Sr sorption tests in solution are therefore carried out to make it possible to validate that the LTA zeolite inserted into the backbone of the geopolymer in the material prepared in Example 1 is indeed active.

The parameter which makes it possible to follow the sorption of Strontium is the Kd (distribution coefficient in mL / g) calculated according to the following formula:

[Math 1] _ {[Sr] _ÎnÎt - [Sr] _end ) V [Sr] _end m

In this formula:

[Sr] ini _t and [Sr] fin respectively represent the initial and final concentration of Sr in solution (mg / L), V is the volume of solution (mL), m is the mass of material (g).

The protocol used for these sorption tests is as follows: 50 mg of material (in monolithic form) are placed in 50 mL of a matrix (aqueous solution) containing 0.05 mol / L of NaN0 3, 50 ppm of Ca (supplied as the Ca (NO3) salt, 2 ppm Cs (supplied as the CSNO3 salt) and 2 ppm Sr (supplied as the SriNOs salt).

Stirred with a rotary stirrer for 24 h.

After stirring, 15 ml of the supernatant is taken with a syringe, and this sample is filtered with a 0.22 μm syringe filter, then the residual Sr concentration is analyzed by inductively coupled plasma spectrometry (ICP).

• The geopolymer monolith without zeolite (Example IA) has a Kd of 1128 mL / g while the geopolymer monolith containing the LTA zeolite particles (Example 1 in accordance with the invention) has a Kd of 5024 mL / g.

This result demonstrates that the LTA zeolite particles integrated into the macroporous geopolymer (Example 1 in accordance with the invention) allow very improved decontamination, almost by a factor of 5.

This result clearly shows the accessibility of the zeolite particles by the contaminated effluent.

Example 2.

In this example, a monolithic material is prepared comprising a geopolymer incorporating a submicron zeolite by various methods in order to study the influence of the manufacturing process on the macroporosity of the monolithic material.

Thus, in order to observe the influence of the manufacturing process on the macroporosity of the material and the interconnectivity of the macropores, the various steps of the PO protocol (called steps 1, 2, 3, 4 and 5 ("UT" ) in example 1) one or two additional steps called “UT” steps. 3 new protocols, called PI, P2 and P3 protocols, were therefore tested and are described in Table 1 below.

The amounts of materials added are similar to those used in Example 1. The final materials obtained using the PO, PI, P2 and P3 protocols therefore have exactly the same final chemical compositions.

[Table 1]

Table 1: Description of the different steps of the PI, P2 and P3 protocols.

It is important to note that the description of the protocols PO, PI, P2, P3 and P4 which is given here in the specific context of example 1 and of example 2 can be easily generalized and that in particular the specific conditions of the various steps can be easily generalized with regard to G “disclosure of the invention” given above.

Whatever the protocol used, an emulsion is systematically stabilized then placed in a mold and left to stand for 48 hours to observe the setting of the geopolymer skeleton and the formation of a cylindrical monolith a few centimeters high and 1 cm high. diameter.

After washing for a period of 24 h in the Soxhlet extractor with a 50-50 mixture of THF-acetone to remove the dodecane, the monolith is allowed to dry for 24 h at 80 ° C.

The interior of each of the monoliths obtained is then observed by scanning electron microscopy (SEM).

The images obtained are shown in Figures 6A, 6B and 6C.

We observe that:

The PI protocol (FIG. 6A) gives rise to so-called “alveolar” materials whose pores appear to be slightly interconnected. The P2 protocol (Figure 6B) generates an intermediate microstructure with residues of alveolar pores, as well as the presence of non-alveolar and more interconnected pores.

The P3 protocol (Figure 6C) gives rise to a large majority of non-alveolar and strongly interconnected pores.

The monoliths are analyzed by nitrogen adsorption-desorption in order to determine their specific surface (Brunauer, Emmett and Teller model, "BET") and their pore size distribution (<60 nm, Barrett model, Joyner, Halenda " BJH ”). Specific surfaces of 33.1, 30.6 and 31.5 m ² .g ¹ are measured for the materials prepared by the protocols P1, P2 and P3 respectively.

Figure 7 shows the pore size distributions (<60 nm) in the three materials.

The pore size distribution of each material is centered on 27 nm, like that obtained for the material synthesized by PO with zeolite.

The modification of the synthesis protocol therefore does not seem to have an influence on the size distribution of the mesopores.

Thus, these results clearly demonstrate an influence of the reversal of the manufacturing steps on the macroporosity and the interconnectivity of the macropores of the material, without modifying the mesoporosity of the walls.

These results show that the P3 protocol is the preferred protocol, then, in order, the PO protocol then the P2 protocol, and finally the PI protocol.

Example 3.

In this example, the influence of the manufacturing process on the efficiency of decontamination of the monolithic material comprising a geopolymer containing submicron LTA zeolite particles is studied.

For this, the efficiency of the materials prepared according to the PI, P2 and P3 protocols for the decontamination of effluents containing Strontium was studied. “Batch” tests similar to those carried out in Example 1D were carried out.

Figure 8 shows the values of the Kd obtained with the materials prepared by the PI, P2 and P3 protocols.

Figure 8 is also plotted the value of Kd obtained with the geopolymer monolith without zeolite (prepared in example IA according to the PO protocol), Kd of 1128 mL / g: see example IC) as well as the value of Kd obtained with the geopolymer monolith containing the LTA zeolite particles and prepared according to the PO protocol (Example 1 in accordance with the invention, Kd of 5024 mL / g: see Example 1D).

A clear difference between the Kd is observed in FIG. 8, which is due to the internal porous microstructures different from the materials making the active zeolite particles more or less accessible to the effluent to be decontaminated.

So :

The materials prepared according to the PO and P3 protocols present non-alveolar and more interconnected microstructures and have higher Kd.

The material prepared according to the PI protocol has a strongly cellular and less interconnected structure and has a Kd only twice that of the material without zeolite.

The material prepared according to the P2 protocol exhibits an intermediate microstructure, consequently generating an intermediate Kd.

Again: these results show that the P3 protocol is the preferred protocol, then, in order, the PO protocol, then the P2 protocol, and finally the PI protocol.

Example 4.

In this example, one proceeds to the manufacture, in accordance with the invention, of a monolithic material comprising a geopolymer incorporating a zeolite of micron size. More precisely, in this example, in accordance with the invention, micron particles of 4A zeolite (known to be an effective and selective adsorbent for Sr in an aqueous medium) are integrated within a macroporous geopolymer matrix.

The micron particles of 4A zeolite are commercial particles manufactured by the company CTI (Céramiques Techniques Industrielles).

Figure 9 shows a SEM image of these particles, the size of which is between 4 and 5 µm.

The P3 production protocol (described in Example 2) is used, the mass of submicron zeolite having been replaced by the same mass of micronic zeolite.

Thus, at the end of the final step of the P3 protocol (“UT” step), a viscous emulsion is obtained.

This viscous emulsion is placed in a mold which is left to stand for

48 h.

After demoulding, a monolithic material is obtained.

This monolithic material is then washed in the Soxhlet extractor with a 50-50 mixture of THF-acetone to remove the dodecane, then it is left to dry at 80 ° C.

After 24 h of drying, a cylindrical monolith a few centimeters in height and 1 cm in diameter is obtained.

The monolith obtained is then ground in powder form. Then an X-ray diffraction (XRD) analysis is performed.

Example 4A.

In this example, a material is produced in the form of a monolith similar to that of Example 4, but not comprising micron particles of 4A zeolite. This monolith is synthesized according to the same protocol, called protocol P3, as in Example 4, but without micronic zeolite, without TTAB and without having added oil to form an emulsion.

The monolith obtained is then ground in powder form. Then we perform an X-ray diffraction analysis (XRD) Example 4B.

In this example, an X-ray diffraction (XRD) analysis of the powders obtained at the end of Examples 4 and 4A is carried out.

A DRX analysis is also carried out on the 4A micron zeolite powder.

The results of these DRX analyzes are shown in Figure 10.

(NB: in Figure 10, it is mentioned "pure geopolymer" · it is the geopolymer synthesized without micronic zeolite, without TTAB and without having added oil to form an emulsion (geopolymer of example 4A)).

The three diffractograms presented in FIG. 10 demonstrate that the micron 4A zeolite particles have indeed been integrated into the structure of the macroporous geopolymer.

Example 4C.

In this example, the effectiveness of the material prepared in Example 4 in accordance with the invention is studied for the decontamination of effluents containing Strontium (Sr).

For this, a “batch” test similar to those carried out in Example 1D was carried out.

A Kd of 5528 mL / g, greater than the Kd of 1128 mL / g of a geopolymer without active particle (see example 1D) is obtained, demonstrating the efficiency of the material.

Example 5.

In this example, one proceeds to the manufacture, in accordance with the invention, of a monolithic material comprising a geopolymer incorporating nanometric particles of crystalline silico-titanates (CST).

More precisely, in this example, in accordance with the invention, nanometric particles of crystalline silico-titanates (CSTs) (known to be an effective and selective adsorbent for Sr in an aqueous medium) are integrated within a matrix - "backbone "- of macroporous geopolymer. The nanometric particles of CST are commercial particles manufactured by the company UOP.

FIG. 11 presents an analysis by laser particle size distribution of these particles which shows that their size is between approximately 10 and 20 nm in solution after dispersion under ultrasound.

The P3 production protocol (described in Example 2) is used, the mass of submicron zeolite having been replaced by the same mass of CST.

Thus, at the end of the final step of protocol P3 (“UT” step), a viscous emulsion is obtained.

This viscous emulsion is placed in a mold which is left to stand for

48 h.

After demoulding, a monolithic material is obtained.

This monolithic material is then washed in the Soxhlet extractor with a 50-50 mixture of THF-acetone to remove the dodecane, and then allowed to dry at 80 ° C.

The monolith obtained is then ground in powder form.

Example 5A.

In this example, a material is produced in the form of a monolith similar to that of Example 5, but not comprising nanometric particles of CST. This monolith is synthesized according to the same protocol, called protocol P3, as in Example 5.

The monolith obtained is then ground in powder form.

Example 5B.

In this example, an X-ray diffraction (XRD) analysis of the powders obtained at the end of Examples 5 and 5A is carried out.

An XRD analysis is also carried out on the nanometric CST powder.

The results of these DRX analyzes are shown in Figure 12. (NB: in Figure 12 it is mentioned pure geopolymer: it is a geopolymer synthesized without CST, without TTAB and without having added oil to form an emulsion (geopolymer of example 4A)).

These 3 diffractograms demonstrate that the nanometric CST particles have been integrated into the structure of the macroporous geopolymer.

Example 5C.

In this example, the effectiveness of the material prepared in Example 5 in accordance with the invention is studied for the decontamination of effluents containing Strontium (Sr).

For this, a “batch” test similar to those carried out in Example 1D is carried out.

A Kd of 4732 mL / g, greater than the Kd of 1128 mL / g of a geopolymer without active particle (see example 1D) is obtained, demonstrating the efficiency of the material.

REFERENCES

[1] FR-A1-2791905.

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[3] Said B., Cacciaguerra T., Tancert F., Fajula F., Galarneau A., “Size control of self-supported LTA zeolite nanoparticles monoliths”, Microporous and Mesoporous Materials, 227 (2016) 176-190.

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Claims

1. A solid material with multiple open and at least partially interconnected porosity, comprising a matrix of a microporous and mesoporous geopolymer, in which are defined open macropores at least partially interconnected delimited by walls or walls of microporous and mesoporous geopolymer, and particles at least one solid compound distinct from the geopolymer being distributed in the macropores and / or in the walls or walls.

2. Material according to claim 1 which is in the form of particles such as grains, granules or beads; or in the form of a monolith; in particular with a size of 300 μm to ten or several tens of cm, for example 10, 30, 40, 50, or even 100 cm.

3. Material according to claim 1 or 2, wherein the particles of at least one solid compound distinct from the geopolymer have an average size, such as a diameter, from 2 nm to 100 µm, preferably from 10 nm to 10 µm.

4. Material according to claim 3, in which the particles of at least one solid compound distinct from the geopolymer are chosen from the group consisting of nanometric particles, submicron particles, and micrometric particles.

5. Material according to any one of the preceding claims, in which the particles of at least one solid compound distinct from the geopolymer are active particles.

6. Material according to claim 5, in which the active particles are chosen from the group consisting of the particles of at least one solid compound exchanging a metal cation, the particles of catalysts, and the particles of adsorbent compounds.

7. Material according to claim 6, in which the solid compound exchanging a metal cation is chosen from the group consisting of zeolites; alkaline silicotitanates; coordination polymer particles (“Metal-Organic Frameworks”), and mixtures thereof.

8. Material according to any one of the preceding claims, wherein the particle content of at least one solid compound distinct from the geopolymer is 0.1 to 30% by mass, preferably 5 to 15% by mass of the. total mass of the material.

9. Process for preparing the material according to any one of claims 1 to 8 which comprises at least the following successive steps: a) is prepared, by mechanical stirring with shear of a mixture comprising an oily phase and an aqueous phase, a oil-in-water emulsion formed of droplets of the oily phase dispersed in the continuous aqueous phase, the aqueous phase comprising an activation solution, an aluminosilicate source capable of forming a geopolymer by dissolution / polycondensation and optionally a surfactant, and particles at least one solid compound being present at the interface formed by the continuous aqueous phase and the droplets of the oily phase dispersed in the continuous aqueous phase of the emulsion; b) the emulsion is allowed to stand, and it is shaped and shaped to obtain a chosen size and shape, and the geopolymer matrix is formed by polycondensation; c) the oily phase is removed, and the material according to any one of claims 1 to 8 is thus obtained.

10. The method of claim 9, wherein the oily phase of the mixture consists of one or more linear or branched alkanes having 7 to 22 carbon atoms, preferably 12 to 16 carbon atoms, such as dodecane and l. 'hexadecane.

11. The method of claim 9 or 10, wherein, prior to step a), the following successive sub-steps a1) to a4) are carried out in order to prepare the mixture comprising an oily phase and an aqueous phase: a1) an aqueous suspension of particles of at least one solid compound is prepared, in water or in an aqueous solution comprising a surfactant; a2) an oily phase is added to the aqueous suspension of particles obtained at the end of step al), whereby a two-phase mixture is obtained comprising the oily phase and an aqueous phase consisting of the aqueous suspension; a3) an aqueous activating solution is added to the aqueous phase of the two-phase mixture obtained at the end of step a2); a4) an aluminosilicate source capable of forming the geopolymer by dissolution / polycondensation is added to the aqueous phase of the two-phase mixture obtained at the end of step a3).

12. The method of claim 11, wherein at the end of step a2), and before step a3), the two-phase mixture comprising the oily phase and an aqueous phase consisting of the aqueous suspension is subjected to stirring. mechanical with shear; and / or at the end of step a3) and before step a4), the two-phase mixture is subjected to mechanical stirring with shear.

13. Use of the material according to any one of claims 1 to 8, for catalyzing chemical reactions, for the filtration of a fluid, or for the separation or extraction of substances contained in a fluid.

14. A process for separating at least one cation of metal or metalloid from a liquid medium containing it, in which said liquid medium is brought into contact with the material according to any one of claims 1 to 8.

15. The method of claim 14, wherein said liquid medium is an aqueous liquid medium, such as an aqueous solution.

16. The method of claim 14 or 15, wherein said liquid medium is chosen from liquids and effluents from industry and nuclear installations and from activities using radionuclides.

17. A method according to any one of claims 14 to 16, wherein said cation is present at a concentration of 0.1 picogram to 500 mg / L, preferably 0.1 picogram to 100 mg / L.

18. A method according to any one of claims 14 to 17, wherein the cation is a cation of an element selected from alkali metals, alkaline earth metals, transition metals, heavy metals, rare earths, actinides, rare gases, and isotopes, in particular radioactive, thereof.

19. Process according to any one of claims 14 to 18, in which the cation is a cation of an element chosen from Sr, Cs, Co, Ag, Ru, Fe and Tl and isotopes, in particular the radioactive isotopes of those. -this.

20. The method of claim 19, wherein the cation is a ¹³⁴ Cs, or ¹³⁷ Cs or ⁹⁰ Sr. cation.