EP3658501A1

EP3658501A1 - Preparation of new aldehyde and/or ketone traps and filters

Info

Publication number: EP3658501A1
Application number: EP18765694.7A
Authority: EP
Inventors: Thu-Hoa Tran-Thi; Ana Borta; Mickael GINEYS; Marie-Pierre SOM; Frédéric HAMMEL
Original assignee: Centre National de la Recherche Scientifique CNRS; Commissariat a lEnergie Atomique CEA; Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Current assignee: Centre National de la Recherche Scientifique CNRS; Commissariat a lEnergie Atomique et aux Energies Alternatives CEA
Priority date: 2017-07-28
Filing date: 2018-07-27
Publication date: 2020-06-03
Also published as: KR102513555B1; CN111094183B; US20200230542A1; WO2019020965A1; KR20200033931A; US11571650B2; FR3069534A1; FR3069534B1; US20230121377A1; CN111094183A; US11904268B2

Abstract

The invention relates to a method for preparing a nanoporous silica sol-gel matrix containing at least one amine reactant selected from hydroxylamine, methylhydroxylamine, tertbutylhydroxylamine, methoxyamine, tetraethylenepentamine, dicarboxylic acid dihydrazides, particularly adipic acid dihydrazide, and the salts thereof, said method comprising the following steps: a) synthesising a gel from tetramethoxysilane or from a mixture of tetramethoxysilane and another organosilicon precursor selected from among phenyltrimethoxysilane, phenyltriethoxysilane, a fluoroalkyltrimethoxysilane, a fluoroalkyltriethoxysilane, a chloroalkylmethoxysilane, a chloroalkylethoxysilane, an alkyltrimethoxysilane, an alkyltriethoxysilane, an aminopropyltriethoxysilane and the mixtures thereof, the synthesis being performed in an aqueous medium at a temperature ranging from 10 to 70°C in the presence of at least one amine reactant selected from among hydroxylamine, methylhydroxylamine, tertbutylhydroxylamine, methoxyamine, dicarboxylic acid dihydrazides, particularly adipic acid dihydrazide, and the salts thereof; b) drying the gel obtained during step a) so as to obtain a sol-gel matrix containing at least one amine reactant.

Description

Preparation of new sensors and filters of aldehydes and / or ketones

The invention relates to a method for preparing a novel nanoporous silicate sol-gel matrix containing at least one amino reactant, the matrix as such and its use as aldehyde and ketone filters. Most of the adsorbent materials used to trap carbonyl compounds such as aldehydes and ketones are porous materials impregnated with reagents capable of reacting with the aldehydes or carbonyl compounds, producing products of different stability and often not colored.

This is the case of RADIELLO® silica cartridges impregnated with 2,4 dinitrophenylhydrazine widely used in the world for the trapping of carbonyl compounds. The products formed by the reaction between hydrazine and aldehydes and ketones are hydrazone derivatives which absorb in the UV and are therefore not colored. On the same principle, the company Dràger (Lubeck, Germany) offers reactive tubes filled either with glass fibers or silica gel (silica gel) impregnated with hydrazine derivatives for the trapping of aldehydes. The hydrazone derivatives obtained are not colored. It should also be noted that RADIELLO® cartridges such as Dràger® tubes are only used for measuring the content of aldehydes and ketones and not as specific filters. The hydrazones formed are eluted and then separated by liquid chromatography and measured optically. For RADIELLO® cartridges such as Dràger® tubes, this involves impregnating the adsorbent material with reagents.

Nanoporous filters for trapping doped aldehydes of an enaminone, preferably of Fluoral-P, have been described in international patent application WO 2007/031657 A2. Such filters are marketed by the company ETHERA under the name Puretech® as selective filters for the trapping of aldehydes with a gradual change of color from pale yellow to dark yellow, orange and brown saturation. This filter, however, traps only the aldehydes; Fluoral-P reacts only with aldehydes and only stains with formaldehyde because it forms with the latter a cyclic compound absorbing in the visible with a maximum centered around 410 nm. Thus, if the filter is used to trap other aldehydes than formaldehyde, the color will not be developed at saturation of the filter. Many amino reactants are known to react with carbonyl compounds such as aldehydes and ketones, such as, for example, ammonia, primary amines, hydroxylamine, hydrazine, phenylhydrazine, semicarbazide and hydrazide. These reactions are all catalyzed in acid medium and the pH of the reaction medium plays an important role in the stability of the products formed. Moreover, these amino compounds when used in the commercialized processes do not produce coloring.

To produce a coloration, it is thus necessary to add a dye to the amino reactants. In a first case described in the literature, Denda et al (Thin films exhibiting multicolor changes induced by formaldehyde -responsive release of anionic dyes, Talanta 144 (2015), 816-822) used protonated primary and secondary amines in a film of polyacrylamide in the presence of various anionic dyes. These form with the cationic amines electrostatic complexes more or less stable. Thus, when the film is immersed in a solution containing formaldehyde, the reaction of the amines with formaldehyde will release the dye which is found released in the solution which is colored. In a second case described in the literature, Suslick et al. (A Simple and Highly

Sensitive Colorimetric Detection Method for Gaseous Formaldehyde; J. Am. Chem. Soc. 2010, 132, 4046-4047) report another method in which the amino reactant is mixed with a pH-sensitive dye in a polyvinylidene difluoride membrane. The variation of the pH during the reaction of the amine with formaldehyde induces a coloring of the dye whose pKa has been chosen wisely.

In both cases, the materials are based on low porosity polymer and the sensors are in the form of thin films to promote the diffusion of formaldehyde, the smallest of the aldehydes. Such a process is not conceivable for the trapping of carbonyl compounds of larger size and especially to make filters for the depollution because it would be necessary to renew the film quickly saturated.

Finally, the filters of the prior art do not always take into account that it is necessary to irreversibly trap and / or avoid releases of pollutant when the trapping reaction is reversible or when the filter reaches saturation. The object of the present invention is thus to propose new materials making it possible to effectively trap aldehydes and ketones present in the ambient air and to prevent their release into the environment.

It is the merit of the inventors to have discovered, very unexpectedly and after much research, that it was possible to achieve this goal with filters based on a nanoporous silicate sol-gel matrix containing in its pores. high concentrations of hydroxylamine chloride derivatives, methylhydroxylamine hydrochloride, tertbutylhydroxylamine hydrochloride, methoxyamine hydrochloride. Under these conditions, these compounds form with the aldehydes and the ketones, in acidic medium, colored reaction products, the color appearing only when the matrix is saturated with these pollutants. For example, a green color is obtained when the pollutant is formaldehyde or acetone and a red-brown color with benzaldehyde. Thus, the filters according to the invention can easily be changed before release of the trapped pollutant (s) can occur. A sol gel matrix is a material obtained by a sol-gel process consisting of using, as precursors, metal alkoxides of formula M (OR) _x R ' _n ' _x where M is a metal, in particular silicon, R is an alkyl group and R is a group bearing one or more functions with n = 4 and x being able to vary between 2 and 4. In the case where M is Si, the alkoxy groups (OR) are hydrolysed in the presence of water in silanol groups (Si - OH). The latter condense to form siloxane bonds (Si-O-Si-). Small particles of size generally smaller than 1 μιη are formed, which aggregate and form clusters which remain in suspension without precipitating, forming a soil. The increase of the clusters and their condensation increases the viscosity of the medium which gels. A porous solid material is obtained by drying the gel, with the expulsion of the solvent outside the formed polymer network (syneresis). The sol-gel matrices obtained from metal alkoxides of the formula M (OR) _x R ' _n ' _x where M is Si are referred to as the sol-gel silicate matrices herein.

By nanoporous matrix is meant a porous matrix whose pores have a size less than 100 nm.

A first subject of the invention therefore relates to a process for the preparation of a nanoporous silicated sol-gel matrix containing at least one amine reactant chosen from hydroxylamine, methylhydroxylamine, tert-butylhydroxylamine, methoxyamine, tetraethylenepentamine and dihydrazides of dicarboxylic acids, especially adipic acid dihydrazide and their salts, said process comprising the following steps: a) synthesis of a gel from tetramethoxysilane or a mixture of tetramethoxysilane and another organosilicon precursor chosen from phenyltrimethoxysilane, phenyltriethoxysilane, a chloroalkylmethoxysilane, a chloroalkylethoxysilane, an alkyltrimethoxysilane, an alkyltriethoxysilane, an aminopropyltriethoxysilane and their mixtures, the synthesis being carried out in an aqueous medium at a temperature ranging from 10 to 70 ° C. in the presence of at least an amine reactant chosen from hydroxylamine, methylhydroxylamine, tert-butylhydroxylamine, methoxyamine, dihydrazides of dicarboxylic acids and especially adipic acid dihydrazide, and their salts;

b) drying the gel obtained in step a) so as to obtain a sol-gel matrix containing the at least one amino reactant.

The sol-gel silicate matrix thus obtained is nanoporous. In one embodiment, the nanoporous sol-gel matrix obtained according to the invention is a so-called microporous matrix having a proportion of micropores greater than 50% with respect to the entirety of the pores. The diameter of these micropores is advantageously between 0.8 and 2 nm. The micropores prevent the molecules of the amino reactant (s) from coming out. While small aldehydes and / or ketones such as formaldehyde, acetaldehyde or acetone, can easily diffuse into the porous network. In another embodiment, the nanoporous sol-gel matrix obtained according to the invention is a so-called mesoporous matrix having a proportion of mesopores greater than 50% with respect to the entirety of the pores. The diameter of these mesopores is advantageously between 2 and 6 nm. Such porosity promotes the diffusion into the pores of larger aldehydes or ketones such as benzaldehyde. As for the probe molecules, present in protonated forms in the pores thanks to the interstitial water, they remain trapped in the matrix because they lose their volatile character.

In both types of microporous or mesoporous matrices, when the aldehyde or ketone comes into contact with the amino reactant (s), the carbonyl group reacts with the amino group to give an imine group. In general, this first reaction does not produce coloring. It requires the presence of a high concentration of amine compounds and pollutants in the pores to induce other reactions that lead to a colored product. By way of example and as indicated above, a green coloration is obtained at saturation when the matrix according to the invention is exposed to formaldehyde or acetone and a red-brown coloration with benzaldehyde.

Here, micropores are understood to mean pores whose diameter is less than 2 nm and mesopores of pores whose diameter is between 2 and 50 nm according to the IUPAC definition. In general, the micropore diameter is 0.8 to 2 nm. In the present invention, in cases where the matrices are essentially microporous, the diameter of the micropores is advantageously centered around 1.1 + 0.1 nm, ie at least 40 to 60% of the micropores have a diameter of about 1.1 + 0.1 nm. In cases where the matrices are essentially mesoporous, the mesopore diameter is generally between 2 and 6 nm. According to the formulations, the mesopore diameter may be between 3 and 6 nm, with a maximum centered around 4.9 + 0.1 nm or between 2 and 5 nm with a maximum centered around 2.6 + 0, 1 nm. In the present invention, the diameter of the mesopores is preferably between 3 and 6 nm and centered around 4.9 + 0.1 nm, that is to say at least 40 to 60% of the micropores have a diameter of about 4.9 ± 0.1 nm. When the expression "comprised between [a first value] and [a second value]" is used in the present application, it is understood that the terminals are included in the indicated range.

The microporous sol-gel matrices according to the invention have a proportion of micropores greater than 50%, preferably from 55% to 98%, more preferably from 60% to 96%, the 100% complement corresponding to the proportion of mesopores. The percentages are expressed with respect to all the pores of the matrix.

The mesoporous sol-gel matrices according to the invention advantageously have a proportion of mesopores greater than 50%, preferably from 55% to 98%, more preferably from 60% to 96%, the 100% complement corresponding to the proportion of micropores. .

Those skilled in the art will be able to choose the ad hoc proportions of micropores / mesopores according to the intended application and its constraints. Thus, for a use of the matrix according to the invention as a filter, the objective is to trap as much as possible the carbonyl pollutant (s) (aldehydes, ketones), while ensuring a long life of the filter and avoiding all release. Therefore, the proportions of high micropores and preferably greater than 50% and more preferably greater than 80%, will be preferred. especially when the targeted pollutants are small (formaldehyde, acetaldehyde, acetone). When pollutants are large in size such as benzaldehyde, the aldehydes / ketones must be rapidly diffused into the matrix in order to trap them and react with the amino compounds to obtain a saturation color change. The high proportions of mesopores will then be preferred and preferably greater than 60% and more preferably greater than 80%.

The nanoporous sol-gel matrices according to the invention are especially characterized in that they have a specific adsorption surface area of 15 + 2 to 900 + 100 m ² · g ^-1 , preferably 150 + 20 m ² · g ^-1. 900 + 100 m ² .g ^_1 . Advantageously, the microporous sol-gel matrices according to the invention also have a specific adsorption surface area of 500 + 50 m ² · g ^-1 to 900 + 100 m ² · g ^-1 , preferably 650 + 70. m ² .g ^-1 at 900 + 100 m ² · g ^_1 and more preferably still 750 + 70 m ² .g ^-1 to 900 + 100 m ² .g ^_1 . The mesoporous sol-gel matrices according to the invention advantageously have a specific adsorption surface area of 15 + 2 to 400 + 40 m ² · g ^-1 and more preferably still 150 + 20 m ² · g ^-1 to 300 + 50 m ² .g ^_1 . The specific surface area and the pore size distribution are determined by analysis of the adsorption-desorption isotherm with liquid nitrogen using the DFT (Functional Density Theory) model.

The synthesis of the gel in step a) of the process according to the invention is advantageously a monotopic synthesis (English: one-pot), that is to say it is carried out in a single step with tetramethoxysilane or the mixture of tetramethoxysilane and the other organosilicon precursor, and the amine reactant (s) in the presence of water and optionally of a polar organic solvent.

The synthesis of the gel in step a) is advantageously carried out using tetramethoxysilane or a mixture of tetramethoxysilane and at least one other organosilicon precursor chosen from phenyltrimethoxysilane, phenyltriethoxysilane, n-fluoroalkyltrimethoxysilane, a fluoroalkyltriethoxysilane and a chloroalkyltrimethoxysilane, a chloroalkyltriethoxysilane, an alkyltrimethoxysilane, an alkyltriethoxysilane, an aminopropyltriethoxysilane and their mixtures, preferably from a chloroalkyltrimethoxysilane, a chloroalkyltriethoxysilane, an aminopropyltriethoxysilane and mixtures thereof, more preferably from a chloropropyltrimethoxysilane, a chloropropyltriethoxysilane, a (C 3 -Cio) alkyltrimethoxysilane, a (C ₃ -C ₁₀ ) alkyl triethoxysilane, an aminopropyltriethoxysilane and mixtures thereof, preferably from a propyltrimethoxysilane, a propyltriethoxysilane, a chloropropyltrimethoxysilane, a chloropropyltriethoxysilane, a propyltrimethoxysilane, a propyltriethoxysilane, an aminopropyltriethoxysilane and their mixtures, more preferentially from a chloropropyltrimethoxysilane and an aminopropyltriethoxysilane, more preferably still from (3-chloropropyl) trimethoxysilane (CITMOS) and (3-aminopropyl) triethoxysilane (APTES) and more preferably still, step a) is carried out from tetramethoxysilane or a mixture of tetramethoxysilane and (3-chloropropyl) trimethoxysilane (CITMOS) or a mixture of tetramethoxysilane and (3-aminopropyl) triethoxysilane (APTES) .

In a particular embodiment, the synthesis of the gel in step a) is advantageously carried out using tetramethoxysilane or a mixture of tetramethoxysilane and at least one other organosilicon precursor chosen from phenyltrimethoxysilane and phenyltriethoxysilane, a fluoroalkyltrimethoxysilane. a fluoroalkyltriéthoxysilane a chloroalkyltriméthoxysilane a chloroalkyltriéthoxysilane, an aminopropyltriethoxysilane and mixtures thereof, preferably from a chloroalkyltriméthoxysilane a chloroalkyltriéthoxysilane, an aminopropyltriethoxysilane and mixtures thereof, more preferably from a chloropropyltrimethoxysilane, a chloropropyltriethoxysilane and aminopropyltriethoxysilane and mixtures thereof, preferably from a chloropropyltrimethoxysilane and an aminopropyltriethoxysilane, more preferably from (3-chloropropyl) trimethoxysilane (CITMOS) and (3-aminopropyl) triethoxysilane (APTES) and more still further step a) is carried out from tetramethoxysilane or a mixture of tetramethoxysilane and (3-chloropropyl) trimethoxysilane (CITMOS) or a mixture of tetramethoxysilane and (3-aminopropyl) triethoxysilane (APTES).

When using a mixture of tetramethoxysilane and another organosilicon precursor, the molar proportions of tetramethoxysilane / other organosilicon precursor can be varied between 1.0 / 0.01 and 1.0 / 0.2, preferably between 1.0 / 0, 01 and 1.0 / 0.04.

The synthesis of the gel in step a) is advantageously carried out in an aqueous medium in the presence of an acid. An acid is a chemical compound, acceptor in the broad sense of electronic doublets, and generally defined by standard reactions in different solvents, in particular by releasing the hydronium ion in the water solvent. Non-limiting examples of acids that may be used in the context of the invention include hydrochloric acid, sulfuric acid, nitric acid, polystyrene sulfonic acid (CAS = 28210-41-5). The acid can also be provided with the amino reagent when it is used in the form of an acid addition salt such as, for example, methoxyamine which is generally used in the form of the hydrochloric acid addition salt. (methoxyammonium chloride). In other words, the acid is provided in this variant of the gel synthesis in aqueous acidic medium in the form of an acid addition salt of the amino reactant. In general, suitable acid addition salts include, but are not limited to, hydrochlorides and hydrogen sulfites (HSO ₃ ), with hydrochlorides being preferred.

The realization of the synthesis in acidic medium makes it possible to obtain better staining performances of the sol-gel matrix when the amine reactant reacts with aldehydes and / or ketones. Particularly good performances are obtained when the pH of the aqueous medium is less than 3, preferably 2.

The synthesis of the gel in step a) is carried out in an aqueous medium. Advantageously, the aqueous medium is water or a mixture of water and a polar organic solvent. The polar organic solvent may be a protic organic solvent, preferably a C1 to C6 aliphatic alcohol, more preferably methanol or ethanol and more preferably still methanol. Those skilled in the art will be able to easily determine the amounts of water and possibly polar organic solvent depending on the organosilicon precursor (s) employed.

The gel preparation step a) uses at least one amine reactant chosen from hydroxylamine, methylhydroxylamine, tert-butylhydroxylamine, methoxyamine, tetraethylenepentamine and dihydrazides of dicarboxylic acids, in particular adipic acid dihydrazide. and their salts, preferably hydroxylamine, methylhydroxylamine, tert-butylhydroxylamine, methoxyamine, dihydrazides of dicarboxylic acids, especially adipic acid dihydrazide, and their salts, preferably still among methylhydroxylamine, methoxyamine, dihydrazides of dicarboxylic acids, especially adipic acid dihydrazide, and their salts, more preferably still among methylhydroxylamine, methoxyamine, dihydrazides of dicarboxylic acids, especially adipic acid dihydrazide, and their salts. Since the amine function of the amine reactants is a basic functional group, they may be in the form of salts. These salts include in particular the acid addition salts. Examples of suitable acid addition salts include, but are not limited to, hydrochlorides, hydrogen sulfites (HSO ₃ ) and adipic acid salts, preferably hydrochlorides and the like. hydrogen sulfites, hydrochlorides being particularly preferred. Also, in a preferred embodiment, the amino reactant is selected from methylhydroxylamine hydrochloride, methoxyamine hydrochloride, tetraethylenepentamine and adipic acid dihydrazide. The amount of amine reactant or mixture of amine reactants is preferably 0.1 mol L ^"1 to 1.0 mol ^{L" 1,} preferably 0.15 mol L ^"1 to 0.8 mol ^{L" 1} and more preferably 0.2 mol.L ^"1 to 0.6 mol.L ^{" 1} of amine reagent. Below 0.1 mol.L ^"1 , the porous matrix will not contain enough reagent to effectively trap aldehydes and / or ketones for a long time and there will be no color change. of 1.0 mol.L ^"1 , the limitation is the mechanical strength of the matrices which is more fragile. With these starting concentrations, at the end of stage b) of the process according to the invention, a porous matrix having an amine reactant content of 0.8 mol is obtained. dm 3 to 8.0 mol.dm 3, preferably 1.2 mol.dm 3 to 6.4 mol.dm 3, more preferably still 1.6 mol.dm 3 to 4.8 mol.dm ³ . The preparation of the gel in step a) is advantageously carried out at a temperature of

10 to 70 ° C. The use of a high temperature makes it possible to accelerate the hydrolysis and condensation of the organosilicon precursors. For example, heating the reaction mixture (sol) at 60 ° C accelerates the gelation by a factor of 6 to 7 compared to a gel preparation at room temperature (20-25 ° C). The gel obtained in step a) is finally dried by evaporation of the water and optionally the organic solvent to obtain the nanoporous sol-gel matrix containing the amine reagent or reagents according to the invention. The evaporation of the water and, if appropriate, of the organic solvent for drying the matrix may be carried out according to any method known to those skilled in the art. The drying may for example be carried out at ambient temperature or at a higher temperature, in particular from 40 to 80.degree. Preferably, the drying is carried out at a temperature ranging from room temperature to 50 ° C, the term ambient temperature denoting a temperature of about 20 ° C. Advantageously, the drying is carried out under an inert atmosphere.

The process according to the invention not only makes it possible to really trap the amine reactant in the pores but also considerably increase its concentration in the matrix, since during the shrinkage during the passage from the ground to the gel, there is a volume contraction by a factor of at least seven, generally from 7 to 10, and therefore an intrapore concentration of amine reactant at least seven times higher, generally 7 to 10 times higher, than in solution. The volume contraction factor of the matrix corresponds to the ratio between the volume of the soil and the matrix after drying. With solution doping, that is to say by impregnation of a nanoporous matrix, the solubility of the dihydrazide is limited and by the equilibrium of the concentrations in the solution and in the matrix.

The invention also relates to the nanoporous silicate sol-gel matrix containing at least one amino reactant chosen from hydroxylamine, methylhydroxylamine, tert-butylhydroxylamine, methoxyamine, tetraethylenepentamine and dihydrazides of dicarboxylic acids, in particular adic acid dihydrazide. , and their salts, obtainable by the process according to the invention as such, that is to say from an amino reactant as defined above and tetramethoxysilane or a mixture of tetramethoxysilane and another organosilicon precursor as defined above. Such a matrix is especially characterized in that it has a specific adsorption surface area of 15 + 2 to 900 + 100 m ² · g ^-1 , preferably 150 + 20 m ² · g ^-1 to 900 + 100 m ² · g ^_1 .

Advantageously, this matrix has a content of reactant (s) amine (s) of 0.8 mol. dm to

8.0 mol.dm 3, preferably 1.2 mol. dm 3 to 6.4 mol.dm 3, more preferably still

1.6 mol.dm 3 to 4.8 mol.dm 3.

In one embodiment, the sol-gel matrix according to the invention is a microporous matrix. It then has a proportion of micropores greater than 50%, preferably 55% to 98%, more preferably 60% to 96%, the complement to 100% corresponding to the proportion of mesopores. The percentages are expressed with respect to all the pores of the matrix. Advantageously, the matrix of this embodiment has a specific adsorption surface area of 500 + 50 m ² .g ^-1 at 900 + 100 m ² · g ^-1 , preferably 650 + 70. m ² .g ^-1 at 900 + 100 m ² · g ^_1 and more preferably still 750 + 70 m ² .g ^-1 to 900 + 100 m ² .g ^_1 . In this embodiment, the content of amino reactant is advantageously from 0.8 mol.dm 3 to 8.0 mol.dm 3, preferably from 1.2 mol.dm 3 to 6.4 mol.dm 3, more preferably still 1.6 mol.dm 3 to 4.8 mol.dm 3.

In another embodiment, the sol-gel matrix according to the invention is a mesoporous matrix. The proportion of mesopores is then greater than 50%, preferably 55% to 98%, more preferably 60% to 96%, the 100% complement corresponding to the proportion of micropores. The percentages are expressed with respect to all the pores of the matrix. The diameter of the mesopores is generally between 2 and 6 nm. According to the formulations, the mesopore diameter may be between 3 and 6 nm, with a maximum centered around 4.9 + 0.1 nm or between 2 and 5 nm with a maximum centered around 2.6 + 0, 1 nm. In the present invention, the diameter of the mesopores is preferably 3 to 6 nm and centered around 4.9 + 0.1 nm, i.e. at least 40 to 60% of the micropores have a diameter of about 4.9 ± 0.1 nm. Advantageously, the mesoporous sol-gel matrices according to the invention have a specific adsorption surface area of 15 + 2 to 400 + 40 m ² · g ^-1 and more preferably still 150 + 20 m ² · g ^-1 to 300 + 50 m ² · g ^-1. The mesoporous silicate sol-gel matrix of this embodiment preferably has an amine reactant content of 0.8 mol. dm 3 to 8.0 mol.dm 3, preferably 1.2 mol. dm 3 to 6.4 mol. dm 3, more preferably still 1.6 mol.dm 3 to 4.8 mol.dm 3.

Thanks to their particular physico-chemical characteristics described above, porous silicate sol-gel matrices containing one or more amino reactants according to the invention are capable of selectively trapping aldehydes and ketones by changing their color to saturation, which makes it possible to change filter and avoid the drawbacks of saturation release encountered with other materials such as activated carbon. When the matrix reaches its saturation color, for example green in the case of formaldehyde or acetone, this indicates that the matrix is saturated and the pollutant can no longer be retained in the micropores of the matrix.

An object of the invention therefore also relates to the use of a nanoporous silicate sol-gel matrix containing at least one amino reactant according to the invention for selectively trapping one or more aldehydes and / or ketones present in the air.

In a first aspect of the use according to the invention, the nanoporous silicate sol-gel matrix containing at least one amine reagent according to the invention is used as an air filter for reducing aldehydes and / or ketones. in particular formaldehyde, acetone and / or benzaldehyde, preferably formaldehyde. The invention therefore also relates to a filter for reducing aldehydes and / or ketones, in particular formaldehyde, acetone and / or benzaldehyde, preferably formaldehyde, comprising a nanoporous silicate sol-gel matrix comprising at least one less an amine reagent according to the invention as well as a process for filtering air by trapping aldehydes and / or ketones present in the air, in particular formaldehyde, acetone and / or benzaldehyde, preferably formaldehyde, in the pores of a nanoporous silicate sol-gel matrix containing at least one amino reactant according to the invention by bringing said matrix into contact with air so as to sequester the aldehydes and / or ketones present in the air in the pores of the said matrix. As described above, when the aldehyde or ketone comes into contact with the amino reactant (s), the carbonyl group reacts with the amino group to give an imine group. In general, this first reaction does not produce coloring. It requires the presence of a high concentration of amine compounds and pollutants in the pores to induce other reactions that lead to a colored product. It is this color change that determines when the filter is saturated.

For use as an air filter for reducing aldehydes and / or ketones, the nanoporous silicate sol-gel matrix according to the invention advantageously has an amino compound content of 0.8 mol.dm 3 to 8, 0 mol.dm 3, preferably 1.2 mol. dm 3 to 6.4 mol.dm 3, more preferably still 1.6 mol.dm 3 to 4.8 mol.dm 3. The sol-gel matrices according to the invention can be used in combination with a purifier of air using activated carbon filters, allowing to trap aldehydes and / or ketones, molecules that activated carbon traps badly or not at all.

In a first embodiment, the nanoporous sol-gel matrix according to the invention used for the filtration of air is a microporous matrix as defined above. This embodiment is particularly suitable for the reduction of aldehydes and / or small ketones such as formaldehyde.

In a second embodiment, the nanoporous sol-gel matrix according to the invention used for the filtration of air is a mesoporous matrix as defined above. This embodiment is particularly suitable for the reduction of aldehydes and / or ketones of large size, in particular benzaldehyde.

Naturally, other embodiments of the invention could have been envisaged by those skilled in the art without departing from the scope of the invention defined by the claims below.

Non-limiting examples of embodiments of the invention are described below. FIGURES

FIG. 1: Concentration curves as a function of time of a filter consisting of the material of Example 3 exposed to formaldehyde: the "upstream" curve for the concentration of formaldehyde measured without filter and the "downstream" curve for the concentration of formaldehyde measured after passing through.

Figure 2: Difference between the "upstream" and "downstream" curves of Figure 1 corresponding to the amount of formaldehyde trapped over time.

EXAMPLES

Abbreviations: TMOS: tetramethoxysilane

Cl-TMOS: 3-chloropropyltrimethoxysilane

MeHA, HCl: methylhydroxyamine hydrochloride

CH30NH2, HC1: methoxyamine hydrochloride

TEPA: tetraethylene pentamine

MeOH: methanol

I. Preparation and analysis of porous sol-gel matrices

Example 1: TMOS Matrix Doped With Methylhydroxyamine:

Reagents: MeHA, HCl (Sigma Aldrich, CAS Number 4229-44-1, Molar mass = 83.52 g / mol, purity 98%), TMOS (CAS number: 681-84-5, Molar mass = 152.2 g / mol and density d = 1.023 mg / L). Plastic honeycomb mold with cylindrical wells 6 mm in diameter and 10 mm deep.

MeHA solution, 5M HCl with 6.264 g dissolved in 15 mL of H ₂ O

V (TMOS) = 7.993 mL

V (H ₂ O) = 23.083 mL

V (MeHA, 5M HCl) = 5.92 mL (0.8M)

V (total) = 37 mL Procedure: In a 60 mL flask, 7.993 mL of TMOS are mixed with 23.083 mL of water with magnetic stirring. The mixture is stirred for 5 minutes, then the 5.92 ml of aqueous solution of MeHA, 5M HCl is added. We observe the formation of two phases and a warming of the mixture which becomes homogeneous over time. When the temperature of the mixture returns to room temperature, the mixture is poured into a honeycomb mold placed in a crystallizer. The mold is covered with an aluminum membrane and placed in a desiccator equipped with a relative humidity indicator. Gelation occurs after 20 hours. Three days after gelation, the aluminum membrane is replaced by a semi-breathable membrane (AB-Gene Greiner one). The dryer is flushed with a flow of inert gas (Ar or N2) at a rate of 300 mL / min and drying is stopped when the humidity indicator indicates between 0.5 to 2% relative humidity.

The dry granules obtained are transparent and pale yellow in color.

After drying, pale yellow transparent gel sol granules with dimensions close to cylinders 3 mm in diameter and 5 mm in length are obtained. Méthylhydroxyamine content in the porous sol-gel matrix is 6.4 mol.dm ^".

Example 2: TMOS / C1-TMOS matrix doped with methoxyamine.

Reagents: CH30NH2, HC1 (Sigma Aldrich, CAS No. 593-56-6, Molar mass = 83.52 gmol- ¹ , purity 98%), TMOS (CAS number: 681-84-5, Molar mass = 152.2 g.mol ^"1 and density d = 1.023 mg.cm ^{" 3} ), Cl-TMOS (CAS RN: 2530-87-2, purity 97%, Molar mass = 198.72 g.mol ^"1 , and density = 1.09 g.cm ^"3) Methanol (CH ₃ OH molecular weight 32.04 g ^{mol" 1,} density = 0.792 g. cm ^", purity 98%). honeycomb plastic mold with cylindrical wells 6 mm in diameter and 10 mm deep.

Solution of CH30NH2, 5M HC1 with 2.506 g dissolved in 6 ml of H ₂ 0

V (TMOS) = 9.182 mL

V (Cl-TMOS) = 0.359 mL

V (MeOH) = 20.589 mL

V (H20) = 0.950 mL

V (CH 3 OH, 5M HCl) = 5.92 mL (0.8 M)

V (total) = 37 mL Procedure: In a 60 mL flask, 9182 mL of TMOS, 0.359 mL of Cl-TMOS are mixed with 20.589 mL of MeOH with magnetic stirring. The mixture is stirred for 5 min, then 0.95 mL of water and 5.92 mL of aqueous CH 3 OH 2 HCl, 5M HCl are added. The mixture is left stirring for 7 days at room temperature and then poured into a honeycomb mold placed in a crystallizer equipped with a relative humidity indicator. The mold is covered with an aluminum membrane and placed in a desiccator equipped with a relative humidity indicator. Gelation occurs after 13 days. Three days after gelation, the aluminum membrane is replaced by a semi-breathable membrane (AB-Gene Greiner one). The dryer is flushed with a flow of inert gas (Ar or N ₂ ) at a rate of 300 mL / min and drying is stopped when the humidity indicator indicates between 0.5 to 2% relative humidity.

The dry granules obtained are translucent and pale yellow in color.

In the present example, the molar proportions of the reactants are TMOS / Cl-TMOS / MeOH / H ₂ 0 / CH 3 OH / HCl = 1 / 0.032 / 8.3 / 6.25 / 0.484. The content of CH 3 OHH 2 in the porous matrix is 6.4 mol. dm ^" .

Example 3: TMOS Matrix of Methoxyamine

Reagents: CH30NH2, HC1 (Sigma Aldrich, CAS No. 593-56-6, Molar mass = 83.52 gmol ^-1 , purity 98%), TMOS (CAS number: 681-84-5, Molar mass = 152.2 g.mol ¹ and density d = 1.023 mg.cm ^" .) Plastic honeycomb mold with cylindrical wells 6 mm in diameter and 10 mm deep.

V (TMOS) = 12.604 mL

V (H2O) = 24.396 mL

CH3ONH2, HCl = 2.52 g (0.815M)

V (total) = 37 mL

Procedure: 2.52 g of CH3ONH2, HCl are introduced into a 60 ml flask and 24.396 ml of water are added. The mixture is stirred until complete dissolution of methoxyamine. 12.064 ml of TMOS are added and the mixture is left under magnetic stirring for 6 hours at the end of which, the mixture is poured into a honeycomb mold placed in a crystallizer. The mold is covered with an aluminum membrane and the mold is placed in a desiccator equipped with a relative humidity indicator. The gelation occurs between 72 and 96 H. the aluminum membrane is replaced by a semi-breathable membrane and the desiccator is swept with a flow of N2 with a flow rate of 300 mL / min and the drying is stopped when the indicator of humidity indicates between 0.5 to 2% relative humidity. The dry granules obtained are white.

In the present example, the molar proportions of the reagents are TM0S / H20 / CH30NH, HC1 = 1 / 16.16 / 0.353. The methoxyamine content in the porous matrix is 6.52 mol.dm ^-3 .

EXAMPLE 4 Matrix TMOS doped dihydrazide of adipic acid Reagents: Adipic acid dihydrazide (Sigma Aldrich, CAS No. 1071-93-8, molar mass = 174.2 g.mol ^-1 , purity 98%), TMOS (CAS number: 681-84-5, Molar mass = 152.2 g.mol ^" and density d = 1.023 mg.cm ^" ). Plastic honeycomb mold with cylindrical wells 6 mm in diameter and 10 mm deep.

V (TMOS) = 12.37 mL

V (H ₂ O) = 24.65 mL

adipic acid dihydrazide = 0.65 g (0.1M)

V (total) = 37 mL

Procedure: 0.65 g of adipic acid dihydrazide are introduced into a 60 ml flask and 24.65 ml of water are added. The mixture is stirred until complete dissolution of the adipic acid dihydrazide. 12.37 ml of TMOS are added and the mixture is left with magnetic stirring. We observe the formation of 2 phases. To accelerate the reaction, the flask is heated to 40 ° C. The mixture is stirred until the mixture becomes homogeneous (20 min). The mixture is poured into a honeycomb mold placed in a crystallizer. The mold is covered with an aluminum membrane and the mold is placed in a desiccator equipped with a relative humidity indicator. Gelation is fast (35 min). After 3 days, the aluminum membrane is replaced by a semi-breathable membrane and the desiccator is flushed with a flow of N2 at a flow rate of 300 mL / min and the drying is stopped when the humidity indicator indicates between 0.5 and 2% relative humidity. The dry granules obtained are white.

In the present example, the molar proportions of the reagents are TMOS / H ₂ O / adipic acid dihydrazide = 1 / 16.64 / 0.044. The content of adipic acid dihydrazide in the porous matrix is 0.8 mol.dm ^".

Example 5: TMOS matrix doped with adipic acid dihydrazide.

Reagents: Adipic acid dihydrazide (Sigma Aldrich, CAS No. 1071-93-8, molar mass = 174.2 g.mol ^-1 , purity 98%), TMOS (CAS number: 681-84-5, Molar mass = 152.2 g.mol ^" and density d = 1.023 mg.cm ^" ) Plastic honeycomb mold with cylindrical wells 6 mm in diameter and 10 mm deep.

V (TMOS) = 12.37 mL

V (H20) = 24.65 mL

adipic acid dihydrazide = 1.3 g (0.2M)

V (total) = 37 mL

Procedure: 1.3 g of adipic acid dihydrazide are introduced into a 60 ml flask and 24.65 ml of water are added. The mixture is stirred until complete dissolution of the adipic acid dihydrazide. 12.37 ml of TMOS are added and the mixture is left with magnetic stirring. We observe the formation of 2 phases. To accelerate the reaction, the flask is heated to 40 ° C. The mixture is stirred until the mixture becomes homogeneous (40 min). The mixture is poured into a honeycomb mold placed in a crystallizer. The mold is covered with an aluminum membrane and the mold is placed in a desiccator equipped with a relative humidity indicator. Gelation is fast (43 min). After 3 days, the aluminum membrane is replaced by a semi-breathable membrane and the desiccator is flushed with a flow of N2 at a flow rate of 300 mL / min and the drying is stopped when the humidity indicator indicates between 0.5 and 2% relative humidity.

The dry granules obtained are transparent.

In the present example, the molar proportions of the reagents are TMOS / H20 / adipic acid dihydrazide = 1 / 16.64 / 0.176. The content of adipic acid dihydrazide in the porous matrix is 1.6 mol.dm ^". Example 6: TMOS matrix doped with dihydrolide of adipic acid and methoxyamine.

Reagents: Adipic acid dihydrazide (Sigma Aldrich, CAS No. 1071-93-8, molar mass = 174.2 g.mol ^-1 , purity 98%), CH30NH2, HCl (Sigma Aldrich, CAS No. 593-56-6 Molar mass = 83.52 gmol ^-1 , purity 98%), TMOS (CAS number: 681-84-5, Molar mass = 152.2 gmol ^" and density d = 1.023 mg.cm ^" ), methanol (CH ₃ OH molecular weight 32.04 g mol ^", density = 0.792 g. ^cm", purity 98%). Plastic honeycomb mold with cylindrical wells 6 mm in diameter and 10 mm deep.

V (TMOS) = 12.604 mL

V (H ₂ O) = 24.396 mL

Adipic acid dihydrazide = 0.65 g (0.1 M)

CH3ONH2, HCl = 1.855 g (0.6 M)

V (total) = 37 mL

Procedure: 0.65 g of adipic acid dihydrazide and 1.855 g of CH3ONH2, HCl are introduced into a 60 ml flask and 24.65 ml of water are added. The mixture is stirred until the two compounds are completely dissolved. 12.604 ml of TMOS are added and the mixture is left stirring magnetically. The formation of 2 phases is observed and the mixture is left stirring until the mixture becomes homogeneous. The mixture is poured into a honeycomb mold placed in a crystallizer. The mold is covered with an aluminum membrane and the mold is placed in a desiccator equipped with a relative humidity indicator. After 3 days after gelation, the aluminum membrane is replaced by a semi-breathable membrane and the desiccator is flushed with a flow of N2 with a flow rate of 300 mL / min. Drying is stopped when the humidity indicator indicates between 0.5 to 2% relative humidity. The dry granules obtained are transparent.

In the present example, the molar proportions of the reagents are TMOS / H2O / adipic acid dihydrazide / CH3ONH2, HCl = 1 / 16.16 / 0.044 / 0.265. The dihydrazide content in the porous matrix is 0.8 mol.dm ^" and that in methoxyamine is 4.8 mol.dm ^{" 3} . Example 7: TMOS matrix doped with dihydric acid of adipic acid and methoxyamine.

V (TMOS) = 17.033 mL

V (H ₂ O) = 32.967 mL

Adipic acid dihydrazide = 1.745 g (0.2M)

CH30NH2, HC1 = 0.42 g (0.1M)

V (total) = 50 mL

Procedure: 1.745 g of adipic acid hydrazide and 0.42 g of CH _{3 0} NH ₂ , HCl are introduced into a 100 ml flask and 32.967 ml of water are added. The mixture is stirred until the two compounds are completely dissolved. 17.033 ml of TMOS are added and the mixture is left stirring magnetically. The formation of 2 phases is observed and the mixture is left stirring until the mixture becomes homogeneous. The mixture is poured into a honeycomb mold placed in a crystallizer. The mold is covered with an aluminum membrane and the mold is placed in a desiccator equipped with a relative humidity indicator. After 3 days after gelation, the aluminum membrane is replaced by a semi-breathable membrane and the desiccator is flushed with a flow of N2 with a flow rate of 300 mL / min. Drying is stopped when the humidity indicator indicates between 0.5 to 2% relative humidity. The dry granules obtained are transparent.

In the present example, the molar proportions of the reactants are TMOS / H ₂ O / adipic acid dihydrazide / CH 3 OH 2, HCl = 1 / 16.16 / 0.0866 / 0.043. The dihydrazide content in the matrix is 1.6 mol.dm ^" and that in methoxyamine is 0.8 mol.dm ^{" 3} . Example 8: TMOS / APTES matrix doped with methoxyamine.

Reagents: CH ₃ 0NH ₂ , HCl (Sigma Aldrich, CAS No. 593-56-6, Molar mass = 83.52 g.mol ^-1 , purity 98%), TMOS (CAS number: 681-84-5, Molar mass = 152.2 gmol ^"1 and density d = 1.023 mg.cm ^{" 3} ), APTES (CAS number: 919-30-2, purity 99%, molar mass = 221.37 g.mol ^" and density d = 0.946 mg.cm ^" ), Methanol (CH ₃ OH, molar mass

2

32.04 g.mol ^", density = 0.792 g. ^Cm", purity 98%). Plastic honeycomb mold with cylindrical wells 6 mm in diameter and 10 mm deep.

Solution of CH30NH2, 5M HC1 with 2.506 g dissolved in 6 ml of H ₂ 0

V (TMOS) = 9.447 mL

V (APTES) = 0.150 mL

V (MeOH) = 20.547

V (H ₂ O) = 0.937 mL

CH30NH2, HCl = 5.92 mL of the 5 M aqueous solution (0.8M)

V (total) = 37 mL

Procedure: 9.447 ml of TMOS and 0.15 ml of APTES are introduced into a 60 ml flask and 20.547 ml of MeOH are added. The mixture is stirred and then 5.92 ml of the aqueous methoxyamine solution, and 0.937 ml of water are added and the mixture is left stirring magnetically. The mixture is poured into a honeycomb mold placed in a crystallizer. The mold is covered with an aluminum membrane and the mold is placed in a desiccator equipped with a relative humidity indicator. After 3 days after gelation, the aluminum membrane is replaced by a semi-breathable membrane and the desiccator is flushed with a flow of N2 with a flow rate of 300 mL / min. Drying is stopped when the humidity indicator indicates between 0.5 to 2% relative humidity.

The dry granules obtained are white.

In the present example, the molar proportions of the reagents are TMOS / APTES / MeOH / H ₂ O / CH 3 NH ₂ HCl = 0.99 / 0.01 / 8/6 / 0.466. The content of methoxyamine in the matrix is 6.4 mol.dm ^". Example 9: TMOS / C1-TMOS matrix doped with methylhydroxyamine in a buffered medium:

Reagents: MeHA, HCl (Sigma Aldrich, CAS Number 4229-44-1, Molar mass = 83.52 g / mol, purity 98%), TMOS (CAS number: 681-84-5, Molar mass = 152.2 g / mol and density d = 1.023 mg / mL), C1TMOS (CAS number: 2530-87-2, Molar mass = 198.7 g / mol, density = 1.09 mg / mL), MeOH (Molar weight = 32.04 g / mol) , d = 0.791 mg / mL, 0.51 M citrate buffer (pH = 4.6), plastic honeycomb mold with cylindrical wells 6 mm in diameter and 10 mm deep.

MeHA solution, 5M HCl with 6.264 g dissolved in 15 mL of H ₂ O

Citrate buffer at pH = 4.6 obtained by mixing 25.5 mL of citric acid (2M) and 24.5 mL of sodium citrate (2M) in 50 mL of water.

V (TMOS) = 22.823 mL

V (Cl-TMOS) = 0.939 mL

MeOH = 13.354 mL

V (H ₂ O) = 0.384 mL

V (MeHA, 5M HCl) = 4 mL (0.4M)

7.5 mL of citrate buffer

V (total) = 50 mL

Procedure: In a 100 mL flask, 22.823 mL of TMOS are mixed with 0.939 mL of Cl-TMOS and 13.354 mL of MeOH. 23.083 mL of water with magnetic stirring. The mixture is cooled to -25 ° C. A second mixture is made with 7.5 mL of buffer solution, 4 mL of the aqueous MeHA solution, HCl and 0.384 mL of water and is poured into the first mixture cooled to -25 ° C. Stirring is maintained for 6 minutes then the mixture is brought to room temperature and poured into a honeycomb mold placed in a crystallizer. The mold is covered with an aluminum membrane and placed in a desiccator equipped with a relative humidity indicator. Gelation occurs after 30-35 min. Two days after gelation, the aluminum membrane is replaced by a semi-breathable membrane (AB-Gene Greiner one). The dryer is flushed with a flow of inert gas (Ar or N2) at a rate of 300 mL / min and drying is stopped when the humidity indicator indicates between 0.5 to 2% relative humidity. After drying, transparent gel sol granules with dimensions close to cylinders 3 mm in diameter and 5 mm in length are obtained. Méthylhydroxyamine the content in the porous sol-gel matrix is 4.0 mol.dm ^".

In the present example, the molar proportions of the reagents are TMOS / ClTMOS / MeOH / H20 / MeHA, HCl / citric acid / sodium citrate =

1 / 0.033 / 2.21 / 4.3 / 0.13 / 0.024 / 0.025

Example 10: TMOS-C1-TMOS matrix doped with tetraethylene pentamine (TEPA).

Reagents: TEPA (Sigma Aldrich, CAS No. 112-57-2, Molar Mass = 194.34 g.mol ^-1 , technical grade, d = 0.998 g / mL), TMOS (CAS Number: 681-84-5, Mass molar = 152.2 g.mol ^"1 and density d = 1.023 mg.cm ^{" 3} ), C1TMOS (CAS number: 2530-87-2, molar mass = 198.7 g / mol, density = 1.09 mg / ml) , Methanol (molecular weight = 32.04 g mol ^"1, d = 0,791g.mL ^_1) HC1 12,18 M. plastic mold honeycomb with cylindrical wells of 6 mm in diameter and 10 mm of depth V (TMOS) = 11,903 mL

V (CITMOS) = 0.469 mL

V (MeOH) = 18.78 mL

V (H 2 O) = 5.938 mL

V (HC1) = 4.51 mL

TEPA = 3.41 mL

V (total) = 50 mL

Procedure: In a 100 mL flask, 11.903 mL of TMOS are mixed with 0.469 mL of C1TMOS and 8.0 mL of MeOH. The mixture is held at -25 ° C and stirred for 10 min. A second mixture of 10.78 mL of MeOH, 3.41 mL of TEPA, 4.51 mL of concentrated HCl (37% fuming HCl, Sigma Aldrich, CAS # 7647-01-0) is poured into the flask. and the final mixture is stirred vigorously for 2 minutes. The mixture is poured into a honeycomb mold placed in a crystallizer. Gelation occurs 5 minutes later. The mold is covered with an aluminum membrane and the mold is placed in a desiccator equipped with a relative humidity indicator. The aluminum membrane is replaced by a semi-breathable membrane and the desiccator is swept with a flow of N2 with a flow rate of 300 mL / min and drying is stopped when the humidity indicator indicates between 0.5 to 2% relative humidity.

The dry granules obtained are transparent and yellow-pale color.

In the present example, the molar proportions of the reagents are TMOS / ClTMOS / MeOH / H2O / HCl / TEPA = 1 / 0.03 / 5.75 / 6.5 / 0.7 / 0.2 The concentration of TEPA in the matrix is 2.88 mol. dm ^" .

IL Characterization of porosity and filtration properties

II.1 Porosity and specific surface area The specific surfaces, pore diameters and proportions of micro- and mesopores were determined by analysis of the adsorption-desorption isotherm with liquid nitrogen (77 K) with the DFT model (Theory of Functional Density) using Quantachrome's Autosorb 1.

The results are summarized in Table 1 below. II.2 Effectiveness of trapping under formaldehyde flux

The underwater entrapment efficiency measurement tests are carried out with gaseous mixtures containing formaldehyde at high concentration with the device described below.

Exposure device for formaldehyde filters

A permeation furnace (PUL010 Calibration-fivespill model) is used to generate a nitrogen gas stream containing formaldehyde. Since formaldehyde is unstable in monomeric form, paraformaldehyde is used. This polymer is put in a permeation tube closed by a permeable membrane and placed in the oven. The oven is heated to 103 ° C to release monomer formaldehyde vapor. A gas flow of 150 mL / min scans the oven. At the outlet of the permeation oven, the concentration of formaldehyde in the nitrogen flow of 150 ml / min is 10.7 ppm or 13.375 mg / m. This mixture is diluted with air wet and is sent into an IL balloon which has 4 exit lanes. The ^ere the output channel is connected to a formaldehyde collector Profile 'air® (Ethera, France), which allows to measure the concentration of formaldehyde in the flask. The 2 ^nd and 3 ^rd tracks are each dedicated to the exposure of a filter and the 4 ^th channel is the vent. In the flask, the concentration of formaldehyde is 900 + 100 ppb with a moisture of 30 + 3%.

Each filter consists of 0.5 g of test material placed in a 3 mL syringe equipped with two tips. The syringe is connected by one of the tips to the mixing gas balloon and the other end to a formaldehyde filter itself connected to a pump. The formaldehyde / air mixture is aspirated with a flow rate of 200 ml / min through the syringe. The concentration of formaldehyde measured upstream (lane 1) and downstream of the filter (lanes 2 and 3) twice a day and makes it possible to deduce the quantity of formaldehyde trapped in each filter after a determined duration of exposure.

Release tests were also carried out to show the irreversibility of the reaction. Each filter already exposed is subjected to a wet flow of N ₂ (50% RH) at a flow rate of 400 ml / min. The flow coming out of the filter is fed into a 500 ml flask, from which the gas is pumped at 200 ml / min for the measurement of formaldehyde with a Profil 'air® sensor (Ethera, France).

Measurement of trapping efficiency

The trapping efficiency of the filters of Examples 1 to 10 was evaluated. The results are summarized in Table 1.

FIG. 1 shows a concentration curve called "upstream" corresponding to the concentration of formaldehyde measured without a filter and a concentration curve called "downstream" measured after passing through a filter consisting of the material of example 3. FIG. 2 represents the difference and corresponds to the amount of formaldehyde trapped over time. With the calculation of the area under this curve, the total amount of trapped formaldehyde is obtained. After 25,000 minutes or 17.4 days, the filter still does not show saturation. The amount of formaldehyde trapped is 10.9 mg / g (g of filter). With the entrapment of formaldehyde, the filter becomes green and the intensity of the coloration increases with the amount of trapped pollutant. Porosity

No. Formulation Sads Efficiency Rate Example (molar ratio) (BET / DFT) trapping mg release

V (pore) CH20 / g of filter

% for x h

micro / mesopor of exposure

es

Distribution

diameters

pore

2 TMOS / ClTMOS / MeOH / H20 / CH30N 404/508 m2 / g 9.56mg / g-124h

H2, HC1 0.16 cc / g

1 / 0.032 / 8.3 / 6.25 / 0.484 93.5% / 6.5%

10-26 To Change

color :

yellow → green

3 TMOS / H20 / CH30NH2, HCl 1060/1150 m2 / g 10.9 mg g- 427h 0.09%

1 / 16.16 / 0.353 0.52 cc / g Change

65.2% / 34.8% color:

11-40 White → green

4 TMOS / H2O / acid dihydrazide 423/316 m2 / g 9.59 mg g -360h 0.30% adipic 1 / 16.64 / 0.044 0.33 cc / g

0% / 100%

21-80 to

TMOS / H2O / acid dihydrazide 267/205 m2 / g 9.03 mg / g -333h 0.33% adipic 1 / 16.64 / 0.088 0.24 cm3 / g

0% / 100%

29-80 To

6 TMOS / H2O / acid dihydrazide 560/420 m2 / g 37 mg / g-450h 0.1% adipic / CH30NH2, HC1 0.32 cc / g

1 / 16.16 / 0.044 / 0.265 16.2% / 83.8%> 50 mg / g to

11-55 At saturation

7 TMOS / H20 / acid dihydrazide 14.3 / 6.5 m2 / g 11 mg / g-288h

adipic / CH30NH2, HC1 0.015 cm3 / g

1 / 16,16 / 0,087 / 0,043 0/100%

36-96 TO

8 TMOS / APTES / MeOH / H20 / 8.91 mg / g 334h

CH30NH2, HC1 White to green

0.99 / 0.01 / 8/6 / 0.446

9 TMOS / ClTMOS / MeOH / H2O / 242/249 m2 / g 4.16 mg / g HOh

MeHA, HCl + citrate buffer pH = 4.7 11-27A

61.9%

TMOS / ClTMOS / MeOH / H20 / HCl 16.18mg / g, 273h

TEPA light yellow-yellow

1 / 0.03 / 5.75 / 6.5 / 0.7 / 0.2 dark / brown II.3 Trapping under a stream of acetone and under a stream of benzaldeh

The underwater trapping efficiency measurement tests are carried out with saturated steam or acetone or benzaldehyde at high concentration by passing the saturated vapor in static mode. For this the filter is exposed above the pure liquid. When exposed matrices exposed to saturated vapor of pollutant, a green color with acetone (tests with samples of Examples 3 and 6) and a red-brown coloring with benzaldehyde (test with sample of l Example 6).

Claims

A process for the preparation of a porous silicate sol-gel matrix containing at least one amine reactant chosen from hydroxylamine, methylhydroxylamine, tert-butylhydroxylamine, methoxyamine, tetraethylenepentamine and dihydrazides of dicarboxylic acids, especially dihydrazide. adipic acid, and salts thereof, said process comprising the following steps: a) synthesizing a gel from tetramethoxysilane or a mixture of tetramethoxysilane and another organosilicon precursor selected from phenyltrimethoxysilane, phenyltriethoxysilane, fluoroalkyltrimethoxysilane, a fluoroalkyltriethoxysilane, a chloroalkylmethoxysilane, a chloroalkylethoxysilane, an alkyltrimethoxysilane, an alkyltriethoxysilane, an aminopropyltriethoxysilane and their mixtures, the synthesis being carried out in an aqueous medium at a temperature ranging from 10 to 70 ° C. in the presence of at least one amine reactant chosen from 1 hydroxylamine, the methylh ydroxylamine, tertbutylhydroxylamine, methoxyamine, dicarboxylic acid dihydrazides, especially adipic acid dihydrazide, and their salts;

b) drying the gel obtained in step a) so as to obtain a sol-gel matrix containing at least one amino reactant.

2. Method according to claim 1, characterized in that the sol-gel porous silicate matrix obtained at the end of step b) has a specific surface area of 15 + 2 m ² .g ^-1 to 900 + 100 m ² . g ^_1, preferably 150 + 20 m ² .g ^-1 to 900 + 100 m ² .g ^-1.

3. Method according to claim 1 or 2, characterized in that the porous silicate sol-gel matrix obtained at the end of step b) has a proportion of micropores greater than 50%, preferably ranging from 55% to 98%. %, more preferably from 60 to 96%, the complement to 100% corresponding to the proportion of mesopores.

4. Method according to claim 3, characterized in that the porous silicate sol-gel matrix obtained at the end of step b) has a specific adsorption surface of 500 + 50 m ² .g ^-1 to 900 + 100. m ² .g ^_1

5. Method according to claim 1 or 2, characterized in that the porous silicate sol-gel matrix obtained at the end of step b) has a proportion of mesopores. greater than 50%, preferably ranging from 55% to 98%, more preferably from 60% to 96%, the 100% complement corresponding to the proportion of micropores.

6. Method according to claim 5, characterized in that the porous silicate sol-gel matrix obtained at the end of step b) has a specific adsorption surface of 15 + 2 m ² .g ^-1 to 400 + 40. m ² .g ^_1 .

7. Method according to any one of the preceding claims, characterized in that the synthesis of the gel in step a) is a monotopic synthesis.

8. Method according to any one of the preceding claims, characterized in that the synthesis of the gel in step a) is carried out from tetramethoxysilane or from a mixture of tetramethoxysilane and at least one other organosilicon precursor chosen from a chloroalkyltrimethoxysilane, a chloroalkyltriethoxysilane, an aminopropyltriethoxysilane and their mixtures, preferably from a chloropropyltrimethoxysilane, a chloropropyltriethoxysilane, an aminopropyltriethoxysilane.

9. The method of claim 8, characterized in that the synthesis of the gel in step a) is carried out from tetramethoxysilane.

10. Method according to claim 8, characterized in that the synthesis of the gel in step a) is carried out from a mixture of tetramethoxysilane and (3-chloropropyl) trimethoxysilane or a mixture of tetramethoxysilane and ( 3-aminopropyl) triethoxysilane (APTES).

11. Method according to any one of the preceding claims, characterized in that the aqueous medium consists of water or a mixture of water and a polar organic solvent.

12. Method according to any one of the preceding claims, characterized in that the synthesis of the gel in step a) is carried out in an aqueous medium in the presence of an acid.

13. The method of claim 12, characterized in that the acid is provided in the form of an acid addition salt of the amino reactant.

14. Process according to any one of the preceding claims, characterized in that the at least one amino reactant is chosen from methylhydroxylamine, methoxyamine, adipic acid dihydrazide and their salts.

15. porous silicate sol-gel matrix containing at least one amino reactant chosen from hydroxylamine, methylhydroxylamine, tertbutylhydroxylamine, methoxyamine, tetraethylenepentamine, dihydrazides of dicarboxylic acids, in particular adipic acid dihydrazide, and their salts; characterized in that it has a specific adsorption surface area of 15 ± 2 m ² .g ^-1 at 900 ± 100 m ² · g ^-1 , preferably 150 ± 20 m ² · g ^-1 at 900 ± 100 m ² . g

16. Sol-gel matrix according to claim 15, characterized in that it has a proportion of micropores greater than 50%, preferably ranging from 55% to 98%, more preferably from 60 to 96%, the complement to 100%. corresponding to the proportion of mesopores.

17. Sol-gel matrix according to claim 16, characterized in that the micropores have diameters of between 0.8 and 2 nm, with a maximum centered around

1.1 + 0.1 nm.

18. sol-gel matrix according to any one of claims 16 or 17, characterized in that it has a specific adsorption surface of 500 + 50 m ² .g ^_1 to 900 + 100 m ^2. ^ ¹ .

19. Sol-gel matrix according to claim 15, characterized in that it has a proportion of mesopores greater than 50%, preferably ranging from 55% to 98%, more preferably from 60 to 96%, the 100% complement. corresponding to the proportion of micropores.

20. Sol-gel matrix according to claim 19, characterized in that the mesopores have diameters of between 3 and 6 nm, with a maximum centered around 4.9 + 0.1 nm or between 2 and 5 nm with a maximum centered around 2.6 + 0.1 nm.

21. Sol-gel matrix according to claim 19 or 20, characterized in that it has a specific adsorption surface of 15 + 2 m ² .g ^-1 to 400 + 40 m ² .g ^-1 .

22. sol-gel matrix according to any one of claims 15 to 21, characterized in that the at least one amino reactant is selected from methylhydroxylamine, methoxyamine, adipic acid dihydrazide and their salts.

23. Use of a porous silicate sol-gel matrix according to any one of claims 15 to 22 or obtained by the process according to any one of claims 1 to 13 for trapping aldehydes and / or ketones present in the air. .

24. Use according to claim 23 characterized in that the matrix is used as an air filter for the reduction of aldehydes and / or ketones.

25. A filter for reducing aldehydes and / or ketones, characterized in that it comprises a porous silicate sol-gel matrix according to any one of claims 15 to 22 or obtained according to the process according to any one of Claims 1 to 14.