Method for Producing Organically Functionalized Inorganic Substrates

Abstract

The present invention discloses a method for producing an organically functionalized solid inorganic substrate, the surface of which comprises a hydroxide and / or oxide comprising an element M, which is a metal or metalloid. The method comprises the steps of drying the surface; optionally removing protons from the surface; and contacting the surface with an organometallic reagent comprising at least one organic functional moiety, thereby obtaining an organically functionalized inorganic substrate, the at least one organic functional moiety being bonded to the hydroxide and / or oxide element M by a direct MC bond, the drying step comprising contacting the surface with a flow comprising an inert gas. The organically functionalized inorganic substrate obtained by the method of the present invention may be used as a membrane, catalyst, sorbent, sensor or electronic component, or as a substrate in filtration, adsorption, chromatography and / or separation processes.

Description

[Technical field]

[0001] The present invention relates to a method for producing organofunctionalized inorganic substrates. In particular, the present invention provides a method for modifying metal or metalloid hydroxides and / or metal or metalloid oxides contained in the surface of an inorganic substrate with organometallic reagents such as Grignard reagents. The present invention further relates to the use of organofunctionalized inorganic substrates obtained by the method of the present invention. [Background technology]

[0002] Ceramic materials, such as membranes, shaped supports or carrier materials, coated layers or powders, are made from inorganic materials, such as silica, titania and zirconia oxides, including mixtures thereof. Compared to polymeric membranes, ceramic membranes exhibit several advantages in that they are chemically inert and feature high mechanical, thermal, chemical and hydrothermal stability. Ceramic materials are known to be robust in extreme processing conditions, such as high temperatures and corrosive environments, and exhibit long service life. Thus, surface-modified ceramics are suitable for use in processes where stability or specific compatibility is required, as well as in those applications where chemical resistance is required.

[0003] Ceramic membranes usually consist of an inorganic substrate, the surface of which comprises hydroxides and / or oxides of element M. Element M is usually, but not necessarily, a metal, such as a transition metal or metalloid. As a result of the presence of hydroxyl and / or oxide groups of element M at the surface, most inorganic substrates tend to be hydrophilic. However, compared to the diversity of functional groups that can be obtained with organic molecules and their functional groups, the diversity of interactions that inorganic substrates can perform is limited. Consequently, this is a limiting factor for the use of inorganic substrates for specific applications. There is therefore a need to adapt the surface properties taking into account the intended application.

[0004] The properties of the surface can be altered by surface modification, also referred to as chemical surface modification, functionalization or grafting. The hydrophilic character can be modified to be more hydrophobic by the addition of further hydrophobic groups and / or the replacement of hydroxyl groups (-OH) or steric hindrance of the surface of inorganic substrates by other groups such as organic functional groups. Other surface properties that can be altered are, for example, the presence and / or number of selective adsorption or interaction sites, anchoring positions for immobilization, chiral sites, reactive sites for further modification, etc.

[0005] A variety of methods have been reported for the surface modification of inorganic substrates, such as solid inorganic substrates, including methods involving co-condensation or grafting reactions with organosilane, organophosphonic acid, or organometallic reagents.

[0006] US Patent Application Publication No. 2006 / 0237361 discloses a method for impregnating ceramic membranes with an organosilane agent having the general formula R 1 R 2 R 3 R 4 Si, where at least one R group is a hydrolyzable group and at least one R group is a non-hydrolyzable group, e.g., alkyl group, phenyl group, which can be at least partially fluorinated. Condensation reaction of the hydrolyzable groups with hydroxide (-OH) groups on the substrate surface bonds the organosilane agent to the surface through MO-Si-R bonds containing oxygen bridges. However, these oxygen bridges are known to be susceptible to hydrolysis, which can result in leaching of the organic functional groups from the substrate during use.

[0007] 'Optimization of reaction conditions for the metalorganic modification of MCM-41', S. Angloher, J. Kecht et al., Chem. Mater. 19, 3568-3574 (2007) discloses the grafting of organometallic reagents on periodic mesoporous silica. The substrate is dried under vacuum at 150° C. for 15 hours, after which the grafting is carried out using organolithium or Grignard reagents, such as n-butyllithium or allylmagnesium bromide, in solvents such as n-hexane or tetrahydrofuran (THF), at temperatures varying between −78° C. and 68° C., and for durations between 2 and 24 hours. The Si-R bond is formed by direct attack of the organometallic reagent at the silicon atom of the siloxane bridge.

[0008] 'Synthesis - properties correlation and the unexpected role of the titania support on the Grignard surface modification', J. Van Dijck, P. Mampuys et al., Applied Surface Science 527 (2020) 146851, discloses the grafting of Grignard reagents on the surface of titania supports. The titania supports were first prepared by 10 -4 mbar and 190° C. for 16 h and subsequently reacted with a Grignard reagent, in particular ethylmagnesium bromide, propylmagnesium chloride or octylmagnesium chloride, in dry tetrahydrofuran (THF) at room temperature for a period of 72 h.

[0009] WO 2010 / 106167 discloses a method for obtaining an organically functionalized inorganic matrix. The method comprises the steps of vacuum drying the inorganic matrix at high temperature, reacting the surface of the dried inorganic matrix with a liquid reagent such as an alcohol by submerging the matrix in the liquid reagent to remove protons from the surface of the matrix, removing the excess liquid reagent, and reacting the matrix with an organometallic reagent. Upon reaction with the organometallic reagent, one or more organic functional groups of the reagent are bonded (grafted) to the surface of the inorganic matrix by direct MC bonds. The total process time comprises several days.

[0010] It is noted that the above-mentioned methods using the grafting of organometallic reagents to attach functional groups to all inorganic substrates include a long drying step in the form of a drying step at vacuum pressure combined with high temperatures to remove all water present on the substrate surface before grafting with the organometallic reagent, which would otherwise react with the organometallic reagent and reduce the amount of reactants available for attachment to the surface.To overcome this undesirable side reaction, state-of-the-art methods report that the long drying combined with high temperatures makes the prior art methods expensive in terms of cost, energy and time. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] US Patent Application Publication No. 2006 / 0237361 [Patent Document 2] International Publication No. 2010 / 106167 [Non-patent literature]

[0012] [Non-Patent Document 1] 'Optimization of reaction conditions for the metalorganic modification of MCM-41', S. Angloher, J. Kecht et al., Chem. Mater. 19, pp. 3568-3574 (2007) [Non-Patent Document 2] 'Synthesis - properties correlation and the unexpected role of the titania support on the Grignard surface modification', J. Van Dijck, P. Mampuys et al., Applied Surface Science 527 (2020) 146851 [Non-Patent Document 3] 'Novel grafting method efficiently decreases irreversible fouling of ceramic nanofiltration membranes', G. Mustafa, K. Wyns et al., Journal of Membrane Science 470 (2014) pp. 369-377 Summary of the Invention [Problem to be solved by the invention]

[0013] The present invention aims to overcome one or more of the above mentioned drawbacks. The aim of the present invention is to provide an improved method for producing organically functionalized solid inorganic substrates, which has one or more of the following advantages: it is better suited for scale-up to industrial scale, it is more economical, it is less complicated, it has a shorter total processing time, it reduces energy consumption and it reduces the number of processing steps. [Means for solving the problem]

[0014] Thus, according to a first aspect of the present invention, there is provided a method as described in the appended claims. The method described herein allows converting a solid inorganic substrate into an organically functionalized inorganic substrate. The surface of the solid inorganic substrate comprises a hydroxide and / or oxide. The hydroxide and / or oxide comprises an element M which is a metal or metalloid. The method comprises the steps of (i) drying the surface of the inorganic substrate; (ii) optionally removing protons from the surface; and (iii) contacting the surface of the inorganic substrate with an organometallic reagent comprising at least one organic functional moiety, thereby obtaining an organically functionalized inorganic substrate. The at least one organic functional moiety is bonded to the element M of the hydroxide and / or oxide by a direct MC bond. The drying step comprises contacting the inorganic substrate with a flow comprising an inert gas.

[0015] A direct MC bond does not include an oxygen bridge between M and C. Without wishing to be bound by theory, the inventors believe that a direct MC bond can be an MC covalent or coordinate bond.

[0016] Advantageously, the drying step is carried out at at least atmospheric pressure.

[0017] Advantageously, the step of contacting the surface with a flow comprising an inert gas is carried out at a temperature of at least 90°C, such as at least 95°C, preferably at least 100°C, such as at least 125°C, more preferably at least 150°C, such as at least 175°C, most preferably at least 200°C, such as at least 225°C, in particular at least 250°C.

[0018] Advantageously, the inert gas is nitrogen, dry air, a noble gas, or a mixture of any two or more thereof. When a noble gas is used, it is preferably argon (Ar) or helium (He). Advantageously, the flow containing the inert gas is a dry flow. Depending on the water content of the mixture of each step, the skilled person is capable of determining the maximum water concentration allowed in the gas flow. For example, the inert gas flow may contain less than or equal to 5% by volume of water, preferably less than or equal to 1% by volume of water, more preferably less than or equal to 0.1% by volume of water, for example less than or equal to 500 ppm of water, or less than or equal to 100 ppm of water.

[0019] Advantageously, the method of the invention also comprises a proton removal step. The proton removal step comprises contacting the surface of the solid inorganic substrate with a reagent capable of reacting with protons at the surface. Advantageously, contacting the surface with the reagent removes reactive protons from the surface. The reagent may be any reagent that the skilled person considers suitable for removing protons from the surface of the substrate. Examples of suitable reagents include alcohols, organophosphonate esters, organophosphonic acid esters, organophosphinic acid esters, organophosphinic acids, or carboxylic acids or carboxylates.

[0020] During the proton removal step, the reagent may be a gas or vapor, i.e. a reagent in the vapor or gas phase. In the context of the present invention, the words gas and vapor are used interchangeably and refer to a reagent in a volatilized state (and thus not liquid or solid). Alternatively, or in addition, the reagent may be a liquid reagent or an aerosol. For example, the surface of the inorganic substrate may be contacted with a first reagent in the vapor phase and a second reagent in liquid form, i.e. a solution.

[0021] According to an embodiment, the flow comprising an inert gas further comprises a reagent such that the drying and proton removal steps are performed simultaneously, i.e. drying and proton removal are obtained simultaneously. Preferably, the reagents contained in the flow comprising an inert gas are present as vapor. Flows comprising an inert gas and gaseous reagents or reagents in the vapor phase can be obtained by methods known in the art. For example, flows can be obtained by bubbling an inert gas through a liquid bath of the reagent, by spraying the reagent in a flow comprising an inert gas, or by evaporating the reagent and subsequently mixing the evaporated reagent with a flow of an inert gas (which can be heated to avoid condensation of the evaporated reagent).

[0022] According to another embodiment, the step of removing protons from the surface of the inorganic substrate comprises contacting the surface with an organometallic reagent. In other words, the organometallic reagent is, according to this embodiment, a reagent capable of reacting with protons at the surface. Advantageously, the organometallic reagent is a liquid, such as a solution of the organometallic reagent in a solvent.

[0023] The organometallic reagent used to remove the protons may be the same or different from the organometallic reagent used to contact the surface of the inorganic substrate to obtain an organofunctionalized inorganic substrate. For example, a first organometallic reagent, preferably in a liquid phase, e.g. a solution of the first organometallic reagent in a first solvent, can be used to remove protons from the surface, and a second organometallic reagent, preferably in a liquid phase, e.g. a solution of the second organometallic reagent in a second solvent, advantageously comprising at least one organofunctional moiety, can also be used to react to obtain an organofunctionalized solid inorganic substrate.

[0024] According to further embodiments, two or more reagents can be used to remove protons from a surface simultaneously, i.e., by exposing the surface to two or more reagents simultaneously, subsequently, i.e., by exposing the surface to a first reagent followed by a further reagent, or in combination with simultaneous and subsequent proton removal, i.e., by exposing the surface to two or more reagents simultaneously followed by a simultaneous subsequent exposure to two or more further reagents. For example, the first reagent may be a gas or vapor contained in a flow of inert gas and the second reagent may be a liquid reagent, such as an organometallic reagent, preferably a solution of the organometallic reagent in a solvent, more preferably a solution of the organometallic reagent diluted in a solvent.

[0025] Preferably, the organometallic reagent is of formula R 1 -M 1 , R 1 -M 1 -X or R 1 -M 1 -R 2 Advantageously, R 1 and R 2 is an organic functional group. 1 and R 2 may be different or the same. The organometallic reagent may also be represented by the formula M 1 (R 1 , R 2 , R 3 ), where R 1 and R 2 is as defined above, and R 3 is an organic functional group, and R 1 and / or R 2 may be different or identical. Advantageously, M 1 is a group Ia element, a group IIa element or Al, in particular Li, Mg or Al. Advantageously, X is a halogen.

[0026] Advantageously, element M is a group IVb metal, ie a group IVb transition metal, a group IVa metal or a group IVa metalloid.

[0027] The method may further comprise a washing step, which advantageously removes any salts present or remaining on the surface of the solid inorganic substrate after contacting the surface with the organometallic reagent.

[0028] The present disclosure further provides the use of an organic functionalized inorganic substrate as described in the appended claims.The organic functionalized inorganic substrate can be used as, but not limited to, a membrane, a catalyst, a sorbent, a sensor or an electronic component.The organic functionalized inorganic substrate can also be used as a substrate in filtration, adsorption, chromatography and / or separation processes.

[0029] In the art of surface modification of inorganic substrates by direct MC bonding, it is considered that the water content of the inorganic substrate and the concentration of reactive, usually acidic, protons at the surface must be as low as possible when the substrate is subjected to the reaction. The reason is that the water remaining in the substrate and the reactive, usually acidic, protons present at the surface are considered to react with the organometallic reactant to such an extent that the desired organic surface modification cannot be achieved. Besides, the formation of a large amount of salts that must be removed and are undesired is expected. It has now been found that the desired degree of organic surface modification can nevertheless be achieved even if a less prolonged drying is performed and the substrate still contains some water. Thus, in the method according to the present disclosure, it is not necessary to carry out expensive and time-consuming (high degree) vacuum drying and can be omitted. Furthermore, it has been found that a separate proton removal step can be omitted and that proton removal can be performed to a sufficient extent by the organometallic reactant. It has been found that the undesired salt formation is thereby negligible. This is surprising.

[0030] Without wishing to be bound by theory, it is believed that during the functionalization step, a portion of the organometallic reagent reacts with remaining water, but the reaction of the organometallic reagent with any remaining water molecules does not significantly reduce the extent to which the surface of the substrate can be functionalized, so long as the amount of water present on the surface is limited. The presence of some water molecules on the surface also does not cause an undesirable degree of salt formation.

[0031] As a result, in the disclosed method, the drying step may therefore be shorter, can be performed at lower temperatures, and / or does not need to be performed under (high) vacuum conditions. This results in a drying step and the overall process having a shorter duration, lower energy consumption, and / or requiring reduced installation costs. The disclosed method is therefore less complex than state-of-the-art methods, allowing for easier scale-up to industrial scale.

[0032] Aspects of the present disclosure relate to the preparation of an organic-functionalized solid inorganic substrate substantially as described herein, and the use of the organic-functionalized solid inorganic substrate as a membrane, catalyst, sorbent, sensor or electronic component. Aspects of the present disclosure relate to filtration, adsorption, chromatography and / or separation processes comprising the preparation of an organic-functionalized solid inorganic substrate substantially as described herein, and the use of the organic-functionalized solid inorganic substrate as a substrate in the process.

[0033] Aspects of the present invention will now be described in more detail with reference to the accompanying drawings, in which like reference numbers illustrate like features. [Brief description of the drawings]

[0034] [Figure 1] 2 illustrates diagrammatically the process steps of a method according to a first embodiment of the invention; [Diagram 2] 5 illustrates diagrammatically the process steps of a method according to a second embodiment of the invention; [Diagram 3] 5 illustrates diagrammatically the process steps of a method according to a third embodiment of the invention; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] According to an aspect of the present invention, a method for functionalizing an inorganic substrate with an organic group is provided.

[0036] The surface of the inorganic substrate comprises a hydroxide and / or an oxide, the hydroxide and / or the oxide comprising the element M. The element M is a metal or metalloid. In particular, the hydroxide may be a hydroxide of M and / or the oxide may be an oxide of M.

[0037] Advantageously, the element M is a group IVb or group IVa metal. Preferably, the metal M is tin (Sn). Alternatively, the element M is a group IVb transition metal, in particular titanium (Ti) or zirconium (Zr).

[0038] Advantageously, element M is a group IVa metalloid, such as silicon (Si), germanium (Ge), antimony (Sb) or tellurium (Te). A preferred example of a metalloid is silicon (Si).

[0039] The oxides and / or hydroxides may comprise combinations of the above elements M, in particular combinations of the above metals and / or metalloids.

[0040] The surface of the inorganic substrate can comprise two or more different hydroxides and / or two or more different oxides, each containing a different element M, or a different combination of elements M. For example, the surface of the solid inorganic substrate can comprise a combination of silica and titania, i.e., a combination of an oxide containing Si and an oxide containing Ti.

[0041] The oxide comprising element M can be present throughout the bulk of the inorganic substrate. In particular, the inorganic substrate consists (substantially) of the oxide. Alternatively, the oxide comprising element M can be provided in a surface layer comprising the (exposed) surface of the inorganic substrate. Possibly, the bulk layer adjacent to the surface layer can be substantially free of oxide. However, the bulk layer can comprise element M, e.g., not an oxide compound. For example, the bulk layer can be or substantially comprise silicon carbide (SiC), and the top layer can substantially comprise silicon dioxide (SiO2).

[0042] The hydroxide comprising element M is advantageously provided on the (exposed) surface of the inorganic substrate, i.e. in the form of hydroxyl groups (-OH) in a surface layer. The bulk layer adjacent to the surface layer may contain hydroxide, but the amount of hydroxide in the bulk layer adjacent to the surface is preferably as small as possible, or the bulk layer adjacent to the surface is substantially free of hydroxide. Possibly, the bulk layer may contain element M as a compound other than hydroxide, for example as an oxide or carbide.

[0043] The inorganic substrate may be porous, for example a porous membrane, a powder containing porous particles, porous particles or porous beads. The inorganic substrate may have high or low porosity, or it may be non-porous. The inorganic substrate may be in the form of a tube, a sheet such as a membrane, a disk, a hollow fiber, a capillary, a particulate powder, a bead, a hollow shell, a coated film, or any other shape that is advantageously permeable to a substance or gas in solution.

[0044] Referring to Figure 1, which illustrates a first embodiment 10 of the method of the present invention, a solid inorganic substrate is provided in step 1. The solid inorganic substrate is dried in drying step 2. Drying step 2 comprises contacting the inorganic substrate with a flow comprising an inert gas. In particular, the exposed surface of the inorganic substrate is subjected to drying step 2.

[0045] Advantageously, the inert gas is nitrogen, dry air, a noble gas, or a mixture of any two or more thereof. When a noble gas is used, it is preferably argon (Ar) or helium (He). Preferably, the inert gas is nitrogen, dry air or argon. Advantageously, the flow comprises at least 75% by volume, such as at least 80% by volume, more preferably at least 90% by volume, such as at least 95% by volume, at least 96% by volume, at least 97% by volume, at least 98% by volume, most preferably at least 99% by volume, such as 99.5% by volume, 99.9% by volume of an inert gas. Preferably, the flow comprising an inert gas consists essentially of one or more inert gases.

[0046] Advantageously, the flow containing inert gas is a dry flow. Depending on the water content of the mixture of each step, the person skilled in the art is capable of determining the maximum water concentration allowed in the gas flow. By way of example, the gas flow may contain less than or equal to 5% by volume of water, preferably less than or equal to 1% by volume of water, more preferably less than or equal to 0.5% by volume of water, such as less than or equal to 0.1% by volume of water, such as less than or equal to 750 ppm of water, less than or equal to 500 ppm of water, less than or equal to 250 ppm of water, or less than or equal to 100 ppm of water.

[0047] Advantageously, the flow rate of the flow comprising the inert gas, i.e. the gas flow rate, is at least 5 ml / min, such as at least 10 ml / min, preferably at least 15 ml / min, such as at least 20 ml / min, at least 25 ml / min, at least 30 ml / min, at least 40 ml / min, at least 50 ml / min, at least 75 ml / min, at least 100 ml / min, at least 125 ml / min, at least 150 ml / min, at least 175 ml / min, at least 200 ml / min, at least 250 ml / min, at least 300 ml / min, at least 350 ml / min, at least 400 ml / min, at least 500 ml / min, at least 600 ml / min, at least 700 ml / min, at least 750 ml / min, at least 800 ml / min, at least 900 ml / min or at least 1000 ml / min. As will be appreciated, the optimal gas flow rate will depend on, but is not limited to, the inorganic substrate, particularly its composition, shape (e.g. film or powder), mass, thickness, surface area, and porosity (if porous), as well as the equipment used, particularly the drying section, drying temperature, and the inert gas, particularly its composition.

[0048] Advantageously, the drying step is carried out at a pressure equal to or greater than atmospheric pressure. Advantageously, the drying step does not involve a vacuum treatment. As will be appreciated, the optimal pressure will depend, but is not limited to, on the nature of the inorganic substrate, in particular its composition, shape (e.g. film or powder), mass, thickness, surface area and porosity (if porous), as well as on the equipment used to perform the drying, in particular the drying compartment, the drying temperature and the nature of the inert gas.

[0049] Advantageously (at least), the surface of the inorganic substrate is contacted with a flow comprising an inert gas at a temperature of at least 90°C, such as 95°C, preferably at least 100°C, such as 110°C, 120°C, 125°C, 130°C, 140°C, 150°C, 160°C, 170°C, 175°C, 180°C, 190°C, more preferably at least 200°C, such as 210°C, 220°C, 225°C, 230°C, 240°C, even more preferably at least 250°C, such as 260°C, 270°C, 275°C, 280°C, 290°C or 300°C or higher.

[0050] The inventors have noticed that contacting the surface of the inorganic substrate with a flow comprising an inert gas at a temperature below 90° C. reduces the quality of the inorganic substrate for further processing steps and of the organic-functionalized inorganic substrate obtained using the method of the present invention. Therefore, the drying step is preferably carried out at a temperature of at least 90° C.

[0051] Advantageously, the drying time, defined as the duration of contacting the inorganic substrate with the flow comprising an inert gas, is between 15 minutes and 48 hours, such as between 30 minutes and 40 hours, between 1 hour and 36 hours, preferably between 1.5 hours and 30 hours, more preferably between 2 hours and 24 hours, such as 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours, 6 hours, 6.5 hours, 7 hours, 7.5 hours, 8 hours, 8.5 hours, 9 hours, 10 hours, 11 hours, 12 hours, 13 hours, 14 hours, 15 hours, 16 hours, 17 hours, 18 hours, 19 hours, 20 hours, 21 hours, 22 hours, 23 hours, 24 hours, 25 hours, 26 hours, 27 hours, 28 hours, 29 hours, 30 hours, 31 hours, 32 hours, 33 hours, 34 hours, 35 hours, 36 hours, 37 hours, 38 hours, 39 hours, 40 hours, 41 hours, 42 hours, 43 hours, 44 hours, 45 hours, 46 hours, 47 hours, 48 ​​hours, 49 hours, 50 hours, 51 hours, 52 hours, 53 hours, 54 hours, 55 hours, 56 hours, 57 hours, 58 hours, 59 hours, 60 hours, 61 hours, 62 hours, 63 hours, 64 hours, 65 hours, 66 hours, 67 hours, 68 hours, 69 hours, 70 hours, 71 hours, 72 hours, 73 hours, 74 hours, 75 hours, 76 hours, 77 hours, 78 hours, 79 hours, 9 hours, 9.5 hours, 10 hours, 10.5 hours, 11 hours, 11.5 hours, 12 hours, 12.5 hours, 13 hours, 13.5 hours, 14 hours, 14.5 hours, 15 hours, 15.5 hours, 16 hours, 16.5 hours, 17 hours, 17.5 hours, 18 hours, 18.5 hours, 19 hours, 19.5 hours, 20 hours, 20.5 hours, 21 hours, 21.5 hours, 22 hours, 22.5 hours, 23 hours, 23.5 hours, or 24 hours.

[0052] The drying time depends on, but is not limited to, the temperature and pressure at which the inorganic substrate is contacted with the flow containing the inert gas, on the composition of the gas flow, in particular on the nature of the inert gas, on the gas flow rate, and on the nature of the solid inorganic substrate, in particular its composition. Lower temperatures may require longer drying times. Higher gas flow rates may lead to shorter drying times. More hydrophilic substrates may require longer drying times.

[0053] Still referring to Figure 1, the drying step 2 is preferably followed by a proton removal step 3. Advantageously, the proton removal step 3 comprises contacting the surface of the solid inorganic substrate with a reagent capable of reacting with protons at the surface of the inorganic substrate.

[0054] The reagent may be selected from a wide range of compounds, such as one or more of an alcohol, an organophosphonate ester, an organophosphonic acid ester, an organophosphinic acid ester, an organophosphinic acid, a carboxylic acid or carboxylate, a catechol, an organosulfonic acid, an alkene, an alkyne, a hydroxamic acid, an alkoxide, or a halogenide. However, the list of suitable reagents is not limited to the aforementioned compounds.

[0055] The reagent capable of reacting with protons may be a gas or a vapor, i.e. a reagent in the vapor phase. In the context of the present invention, the words gas and vapor are used interchangeably and refer to a reagent in a volatilized state and thus neither liquid nor solid. Alternatively, or in addition, the reagent may be an aerosol, or a liquid reagent, such as an organometallic reagent. Liquid reagents may be used in the form of a solution or emulsion. The proton removal step carried out using a gas or vapor as reagent is preferably carried out at a temperature of at least 90° C. to counteract the re-adsorption of water on the substrate surface.

[0056] The surface of the solid inorganic substrate can be contacted simultaneously or sequentially with two or more reagents capable of reacting with protons at the surface. The two or more reagents can have an affinity, allowing them to be used simultaneously to remove protons from the surface of the inorganic substrate, e.g., both reagents react with the surface but not with each other. The two or more reagents can be incompatible, and they are preferably used in successive proton removal steps. For example, the substrate can be contacted with a first reagent in the vapor phase and a second reagent in liquid form, or with a first liquid reagent and a second liquid reagent prepared together, such as a solution containing both liquid reagent and a solvent.

[0057] When a gas or vapour is used, the proton removal step is advantageously carried out at a temperature of at least 90°C, for example 95°C, preferably at least 100°C. The inventors have discovered that when the proton removal step 3 is carried out at a temperature below 90°C by contacting the gaseous reagent or reagent with the surface in the vapour phase, water formed in the proton removal may remain on the surface. Such water may reduce the quality of the inorganic substrate for further processing steps and of the organo-functionalised inorganic substrate obtained using the method of the invention. When the proton removal step is carried out using a liquid, lower temperatures can be maintained.

[0058] The proton removal step 3 is followed by an optional purging step 4 in which the surface of the inorganic substrate is contacted with a purging compound to remove excess reagent from the surface and the reactor. The purging compound can include an additional flow comprising a gas, such as an inert gas. The additional flow comprising an inert gas can have the same or a different composition as the flow comprising an inert gas used for drying the substrate. Alternatively or additionally, the purging compound can include a liquid, such as a solvent.

[0059] The temperature at which the purge step is carried out may be varied and may be selected by the skilled artisan, taking into account the nature of the proton-removing agent used, so as to be high enough to ensure desorption of the agent removing the adsorbed protons from the substrate surface. Preferably, the optional purge step 4 is carried out at a temperature of at least 25°C, such as at least 30°C or at least 50°C or at least 90°C, such as 95°C, preferably at least 100°C, such as 110°C, 120°C, 125°C, 130°C, 140°C, 150°C, 160°C, 170°C, 175°C, 180°C, 190°C, more preferably at least 200°C, such as 210°C, 220°C, 225°C, 230°C, 240°C, even more preferably at least 250°C, such as 260°C, 270°C, 275°C, 280°C, 290°C, or 300°C or higher. The temperature of the purge step may be the same as that of the drying step.

[0060] The purging step 4 may be carried out for a period between 15 seconds and 120 minutes, such as between 30 seconds and 100 minutes, for example between 1 minute and 90 minutes, preferably between 2 minutes and 60 minutes, such as between 5 minutes and 50 minutes, more preferably between 10 minutes and 45 minutes, for example between 15 minutes and 30 minutes.

[0061] The functionalization step 5 involves contacting the surface of the inorganic substrate with an organometallic reagent, thereby obtaining an organo-functionalized inorganic substrate.

[0062] Advantageously, the organometallic reagent comprises at least one organofunctional moiety. Advantageously, upon contacting the surface with the organometallic reagent, at least one organofunctional moiety of the organometallic reagent is bonded directly to element M of the hydroxide and / or oxide by an MC bond.

[0063] The direct MC bond may be a covalent or coordinate bond that forms an organometallic complex with M. The direct MC bond does not include an oxygen bridge between M and C.

[0064] Advantageously, the organometallic reagent is of formula R 1 -M 1 , R 1 -M 1 -X or R 1 -M 1 -R 2 Alternatively, the organometallic reagent is a component of formula M 1 (R 1 , R 2 , R 3 Advantageously, R 1 , R 2 , R 3 is an organic functional group. 1 , R 2 , R 3 Two or all of may be different or identical. For example, R 1 and R 2 may be identical, R 3 is R 1 and R 2 may be different from.

[0065] Part R 1 , R2 and R 3 The moiety R may include any functional group that is compatible with organometallic compounds. 1 , R 2 and R 3 also includes any functional group that is provided in protected form, i.e., incompatible with the organometallic compound bearing a protecting group. Protecting groups are well known in the art and will not be disclosed in detail herein.

[0066] R 1 , R 2 and R 3 Examples of moieties include, but are not limited to, alkyl, haloalkyl, aryl, haloaryl, amines (primary, secondary and tertiary amines), thiols, chiral hydrocarbons, and any combination thereof.

[0067] Preferably, R 1 , R 2 and R 3 is an alkyl, preferably C 1~16 Alkyl, more preferably C1-C8 alkyl; haloalkyl, preferably fluoroalkyl or perfluoroalkyl, more preferably fluoro C1-C 16 Alkyl or perfluoro C1-C 16 Alkyl, more preferably fluoro C1-C8 alkyl or (per)fluoro C1-C8 alkyl; aryl, preferably C6-C 18 Aryl, more preferably C6-C 12 Aryl; haloaryl, preferably fluoroaryl or perfluoroaryl, more preferably fluoroC-C 18 Aryl or perfluoro C6-C 18 Aryl, more preferably fluoro C6-C 12 Aryl or perfluoro C6-C 12 aryl; and any combination thereof.

[0068] In certain embodiments, R 1 , R 2 and / or R 3is selected from the group comprising amines, diamines, triamines, thiols, chiral hydrocarbons, and any combination thereof. Combinations in this context may include combinations within these groups as well as combinations between groups.

[0069] As used herein, R 1 , R 2 or R 3 The moiety may include linear, branched or cyclic molecules. For example, the term "alkyl" is intended to include linear, branched, as well as cyclic alkyls. The term "aryl" is intended to include monocyclic, polycyclic, or heterocyclic aryls. The term "haloalkyl" is intended to include alkyl as defined herein substituted with one or more halogen atoms. The term "(per)fluoroalkyl" is intended to include alkyl as defined herein substituted with one or more fluorine atoms. The term "haloaryl" is intended to include aryl as defined herein substituted with one or more halogen atoms, preferably substituted with 1 to 5 halogen atoms. The term "(per)fluoroaryl" is intended to include aryl as defined herein substituted with one or more fluorine atoms, preferably substituted with 1 to 5 fluorine atoms.

[0070] Whenever the term "substituted" is used in the context of the present invention, it is intended to indicate that one or more hydrogens or carbons on the atom indicated in the phrase using "substituted" are replaced with a selection from the indicated group, provided that the standard valence of the indicated atom is not exceeded and that the substitution results in a chemically stable compound, i.e., a compound that is sufficiently robust to survive isolation to a useful degree of purity from a reaction mixture.

[0071] Advantageously, M 1 is a group Ia element, a group IIa element, or Al. 1 is Li, Mg or Al.

[0072] Advantageously, X is a halogen. Preferably, X is Br, Cl or I.

[0073] Specific examples of suitable organometallic reagents are organomagnesium reagents (preferably Grignard reagents), organolithium, organoaluminium and derivatives.

[0074] Organolithium reagents refer to organometallic reagents that have a direct bond between the carbon and lithium atoms. Organolithium reagents are R 1 is a moiety as defined herein above, 1 -Li.

[0075] Organomagnesium reagents refer to organometallic reagents that have a direct bond between the carbon and magnesium atoms. Organomagnesium reagents have the general formula R 1 -Mg-X or R 1 -Mg-R 2 [In the formula, R 1 and R 2 is a moiety as defined herein above, and X is a halogen atom, preferably Br, Cl or I. The organometallic reagent used within the present invention is more preferably a Grignard reagent.

[0076] Non-limiting examples of Grignard reagents are phenylmagnesium chloride, phenylmagnesium bromide, propylmagnesium chloride, propylmagnesium bromide, pentylmagnesium chloride, pentylmagnesium bromide, octylmagnesium chloride, octylmagnesium bromide and methylmagnesium bromide.

[0077] Organometallic reagents, and in particular Grignard reagents, are known to be very reactive. In particular, they are strong bases and therefore react easily with hydroxides of element M, a metal or metalloid contained in the surface of inorganic substrates. In their reactive conditions, the organometallic reagents may leave salts on the surface after bonding to the functional moiety and element M by a direct MC bond or after deprotonation. These salts have proven difficult to remove from the surface, requiring a cleaning step using harsh conditions or at least two successive cleaning steps. Furthermore, the use of organometallic reagents in their pure and undiluted form may lead to an unsafe processing environment due to their high reactivity.

[0078] The inventors have discovered that using an organometallic reagent diluted in a solvent offers several advantages, including a more stable organometallic reagent, reduced salt formation, and a safer processing environment. Although the absolute amount of organometallic reagent present or used may be less than neat dilution of the reagent in a solvent, the reduced salt formation and improved stability make it possible to obtain the same or even improved degree of modification of inorganic substrates in a safer processing environment.

[0079] Advantageously, step 5, contacting the surface of the inorganic substrate with the organometallic reagent, is carried out in liquid phase, comprising the organometallic reagent diluted in a solvent. The solvent may be any solvent known in the state of the art to be compatible with the organometallic reagent. Examples of suitable solvents are tetrahydrofuran (THF), diethyl ether, cyclopentyl methyl ether, or a mixture of any two or more thereof.

[0080] Preferably, the solvent is a dry solvent. The solvent is considered to be dry when it contains up to 250 ppm water, preferably up to 200 ppm water, more preferably up to 150 ppm water, for example, up to 125 ppm water, up to 100 ppm water, up to 90 ppm water, up to 80 ppm water, up to 70 ppm water, up to 60 ppm water, up to 50 ppm water, up to 40 ppm water, up to 30 ppm water, up to 25 ppm water, or up to 20 ppm water. For example, when 0.067M Grignard reagent is diluted in THF for the treatment of 1 gram of TiO2 (titania) powder as solid inorganic substrate, the THF is considered to be substantially dry when it contains up to 100 ppm water.

[0081] The inventors have surprisingly found that some water molecules may be present in a solution of the organometallic reagent diluted in a solvent. For example, it has been shown that the reagent can react with water molecules without affecting the degree of modification of the inorganic substrate. However, it is clear that the lower the amount of water, the less the organometallic reagent is consumed by reactions other than the bonding of its functional moiety to the element M and is therefore preferred. The possible presence of limited amounts of water allows the use of less dry solvent, which is usually less expensive, thereby reducing the overall cost of the process.

[0082] Advantageously, step 5, of contacting the surface with an organometallic reagent comprising at least one organofunctional moiety, is carried out at a temperature between −80° C. and 75° C., such as between −75° C. and 75° C., between −50° C. and 75° C., between −25° C. and 70° C., between −10° C. and 70° C., between 0° C. and 70° C., between 5° C. and 65° C., preferably between 10° C. and 60° C., such as between 12° C. and 55° C., between 15° C. and 50° C., more preferably between 18° C. and 45° C., such as at about room temperature. If the organometallic reagent is diluted in a solvent, the temperature is preferably below the boiling point of the solvent.

[0083] Advantageously, the organometallic reagent, particularly the Grignard reagent, is a strong base and is capable of removing all remaining protons on the surface, whether or not an additional proton removal step is performed.

[0084] The functionalization step 5 may be followed by an optional washing step 8. Advantageously, the washing step is carried out by methods well known to those skilled in the art and may include, for example, washing with water, a solvent and / or with an acid, such as, for example, a dilute acid. The washing step 8 may be carried out in a single step or in multiple steps, advantageously without requiring the use of harsh conditions.

[0085] A second embodiment 20 of the method of the present invention is depicted in FIG. 2. The embodiment 20 differs from the embodiment 10 in that the step 2 of drying the inorganic substrate and the step 3 of removing protons are combined into a single step 6. All other steps are equal to the embodiment 10. In particular, the flow containing an inert gas used in the drying step 2 further contains a proton removing reagent, so that the drying step and the proton removing step are performed simultaneously in the step 6. In other words, the surface of the inorganic substrate is dried and the protons are removed therefrom by the same flow flowing over the surface of the inorganic substrate. The flow containing an inert gas and a reagent can be considered as a reactive gas flow. Preferably, the reagent contained in the flow containing an inert gas is present as a gas or vapor or aerosol.

[0086] The present inventors have surprisingly discovered that with a proton-removing agent present during the drying process, drying can be accomplished at lower temperatures.

[0087] A flow comprising an inert gas, a gaseous reagent or a reagent in the vapor phase can be obtained by methods known in the art, for example by bubbling an inert gas through a liquid bath of the reagent, by spraying the reagent in a flow comprising an inert gas, or by evaporating the reagent and subsequently mixing it with a flow of inert gas, which can be heated to avoid condensation of the evaporated reagent.

[0088] The reagent used for proton removal according to the second embodiment 20 may be, but is not limited to, an alcohol, a phosphonate ester, a phosphonic acid ester, a phosphinic acid, a phosphinic acid ester, a carboxylic acid or carboxylate, a hydroxamic acid, an alkoxide, a halogenide, or any combination of two or more thereof. The alkoxide is preferably a metal alkoxide. The most suitable reagent for proton removal depends on the composition of the inorganic substrate surface, and in particular on the element M. The skilled person is capable of selecting the most suitable reagent.

[0089] Preferred reagents are those which form water molecules upon removal of protons from the surface of the inorganic substrate, since the formed water molecules are removed from the surface and the drying apparatus by combining the drying step 2 and the proton removal step 3 as described in a single step 6 in connection with FIG.

[0090] Preferably, the reagent is an alcohol. The alcohol may be aliphatic or aromatic. The alcohol may be linear, branched or cyclic, and optionally contains one or more side chains, which may be linear or branched. Preferably, the alcohol has the formula R 10 -OH, where R 10 is alkyl, preferably C 1~8 Alkyl, e.g. C 1~6 Alkyl, more preferably C 1~4 Alkyl, most preferably C 1~2 Preferred examples of alcohols are methanol, ethanol, isopropanol and butanol.

[0091] The amount of reagent contained in the flow containing the inert gas is not particularly limited. The flow of inert gas can be saturated with the reagent, especially if the reagent exists as a vapor. Alternatively, the flow of inert gas can contain the reagent in an amount below the saturation level.

[0092] Advantageously, the temperature of step 6 of combined drying and proton removal is high enough to minimize physisorption of the proton-removing reagent. Physisorption is the binding of the reagent to the surface of the inorganic substrate instead of the reagent that removes one or more protons and should therefore be minimized and preferably avoided. For example, if the reagent is an alcohol such as methanol, the temperature is preferably as indicated in relation to drying step 2 of embodiment 10, i.e. at least 90°C, for example at least 100°C, preferably at least 150°C, more preferably at least 175°C, most preferably at least 200°C. The inventors further realized that at temperatures below 90°C, dissociative adsorption of the proton-removing reagent may be impaired and physisorption of the reagent and / or the water formed may occur, thereby reducing the quality of the organically functionalized inorganic substrate obtained using the method of embodiment 20.

[0093] One advantage of working at a temperature that minimizes physisorption of reagents is that it minimizes recondensation at the surface of water molecules that were released from the surface during drying or formed during proton removal.

[0094] One advantage of the presence of a reagent in the flow with an inert gas is that it can improve the evacuation of water molecules leaving the surface and leaving the device. Thus, step 6, which combines drying and proton removal, reduces the drying time and / or drying temperature to reach a given level of drying compared to prior art drying methods. Furthermore, since protons are also removed simultaneously, the total process time is reduced in two ways compared to prior art methods and also compared to embodiment 10: - the drying time is reduced and a separate proton removal step is eliminated - the number of processing steps is reduced as well.

[0095] A third embodiment 30 of the method of the invention is represented in Figure 3. The embodiment 30 differs from the first embodiment 10 in that the proton removal step 3 and the functionalization step 5 are combined in a single step 7. In such a case, protons are removed from the surface simultaneously with the attachment of at least one organic functional moiety to the hydroxide and / or oxide element M by a direct MC bond, thereby obtaining an organic-functionalized inorganic substrate. As a result, the optional purging step 4 is not performed in the embodiment 30. The steps 1 of providing the inorganic substrate, the drying step 2 and the optional washing step 8 can be carried out as described in connection with the embodiment 10.

[0096] In step 7, the organometallic reagent that removes protons may be the same or different from the organometallic reagent that reacts with the surface of the inorganic substrate, ie, the reagent used in step 5 above.

[0097] When the organometallic reagent used in step 7 is the same for removing the proton and reacting with the surface, a first portion of the organometallic reagent can remove a proton from the surface, while a second portion of the organometallic reagent can simultaneously react with the surface to bind a functional moiety to element M, thereby obtaining an organo-functionalized inorganic substrate.

[0098] If different organometallic reagents are used in step 7 for deprotonation and for reaction with the surface, a mixture of reagents is advantageously used to perform simultaneous deprotonation and functionalization of the surface.

[0099] The preferred organometallic reagent used in step 7 is a Grignard reagent.

[0100] The advantage of simultaneously removing protons and functionalizing the surface of the substrate in a single step 7 is that the total processing time is reduced and the process is less complicated.

[0101] It is convenient to note that the steps of embodiments 20 and 30 can be combined. In particular, in a fourth embodiment (not shown), embodiment 20 is modified in that step 5 is replaced with step 7 of embodiment 30. Thus, a first portion of protons is removed from the surface of the inorganic substrate as in step 6. An organometallic reagent then removes a second remaining portion of protons from the surface of the inorganic substrate in step 7 as described above.

[0102] The organic-functionalized inorganic substrates obtained by the method of the present disclosure are advantageously used as membranes, sorbents, catalysts, sensors or electronic components. The organic-functionalized inorganic substrates obtained by the method of the present disclosure can further be used as substrates for filtration, adsorption, chromatography and / or separation processes. EXAMPLES

[0103] Example 1 As reference samples (Reference Samples 1 and 2 in Table 1), organically functionalized inorganic substrates were prepared by prior art processes.

[0104] Titania powder was used as the solid inorganic substrate and was prepared according to the details disclosed in 'Synthesis - properties correlation and the unexpected role of the titania support on the Grignard surface modification', J. Van Dijck, P. Mampuys et al., Applied Surface Science 527 (2020) 146851.

[0105] 10 in the absence of inert gas flow -4 Reference sample 1 was obtained by drying the surface of the titania powder at 190°C and 1000 mbar pressure for 16 hours. Protons were then removed from the surface of the dried titania powder by submerging the dried substrate in liquid methanol (50 ml) at 120°C for 48 hours. -4The powder was dried at 0.5 MPa (16 h at 1000 sq. mbar pressure) to remove any remaining methanol from its surface, and then the powder was contacted with octylmagnesium chloride (abbreviated as 8Gr), an organometallic reagent, diluted in 30 ml of THF at a concentration of 2 mmol per gram of titania substrate, for 24 h at room temperature (RT) to obtain Reference Sample 1.

[0106] The same drying as for Reference Sample 1 was carried out to obtain Reference Sample 2. Then, a combined proton removal and surface functionalization process was carried out by contacting the powder with 8Gr diluted in 30 ml of THF at a concentration of 2 mmol per gram of titania substrate for 24 hours at room temperature (RT) to obtain Reference Sample 2.

[0107] The degree of modification was measured by thermogravimetric analysis (TGA), and was 0.80 groups / nm for reference sample 1. 2 and 0.79 groups / nm for reference sample 2. 2 This was 0.7 atoms / nm 2 which is considered a minimum value for a good degree of modification for this type of titania substrate and this organometallic reagent.

[0108] Example 2 Three samples (samples 1, 2 and 3 in Table 1) were prepared according to the second embodiment of the present invention. The process parameters of the combined drying and proton removal step were varied. The inorganic substrate was the same as that for the reference sample.

[0109] Methanol was used as the reagent for proton removal. A flow of 30 ml / min of N2+methanol (vapor) was used for a duration of 4 hours, and methanol was added to the N2 until the N2 was saturated with methanol. The temperatures used were 80°C, 100°C and 200°C.

[0110] The substrate was then contacted with 8Gr diluted in 30ml of THF at a concentration of 2mmol / g of titania powder at room temperature for 24 hours to obtain an organic functionalized inorganic substrate. In other words, the functionalization process was the same as that of the reference sample in Example 1.

[0111] The degree of modification was measured as described above. From Table 1, it can be seen that for a temperature of 80° C., the degree of modification is not sufficient (0.63 groups / nm ) for this particular combination of titania powder and organometallic reagent (8Gr). 2 It is clear that at this temperature physisorption of methanol occurred and, as explained above, the water probably recondensed and was 2 ) and 200°C (0.76 groups / nm 2 The degree of modification was found to be lower than that of the same process performed in the previous study. 2 If so, samples 1 and 2 show similar quality to the reference sample.

[0112] Example 3 Three samples (samples 4, 5 and 6 in Table 1) were prepared according to the third embodiment of the present invention, and the process parameters of the drying step were varied. The inorganic substrate was the same as that of Examples 1 and 2.

[0113] Drying was accomplished by using a flow of N2. The flow rate was varied between 30 ml / min and 100 ml / min. The temperature was varied between 200° C. and 250° C. The duration was varied between 4 h and 16 h.

[0114] The substrate was then contacted with 8Gr diluted in 30ml of THF at a concentration of 2mmol / g titania powder at room temperature for 24 hours to remove protons and attach at least one functional moiety, thereby obtaining an organic-functionalized inorganic substrate. In other words, the functionalization process was the same as that of Reference Sample 1.

[0115] The degree of modification was measured as described above, see Table 1. When drying was performed at 200° C., the degree of modification after 4 hours was 0.67 groups / nm for this particular titania powder and organometallic reagent. 2 ), even with an increased flow rate of 100 ml / min, good modification was obtained (0.77 groups / nm) after 16 h at a lower flow rate of 30 ml / min. 2 ). The tolerance is 0.1g / nm 2If so, sample 4 shows a similar quality to the reference sample. By increasing the temperature to 250°C and maintaining a flow rate of 30 ml / min, a borderline sufficient degree of modification can be obtained after 4 hours (0.71 groups / nm 2 ).

[0116] [Table 1]

[0117] Example 4 The degree of irreversible fouling was measured for an untreated single tubular TiO2 membrane (delivered by Inopor) with a top layer with a pore size of 0.9 nm, an outer diameter of 10 mm and a length of 25 cm (sample "untreated" in Table 2). This was done by measuring the water flux after fouling the membrane with humic acid as disclosed in 'Novel grafting method efficiently decreases irreversible fouling of ceramic nanofiltration membranes', G. Mustafa, K. Wyns et al., Journal of Membrane Science 470 (2014) 369-377, and comparing it with the water flux before fouling. The normalized water flux, also called the reforming grade, is defined as the ratio of the water flux after fouling to the water flux before fouling and is a measure of the irreversible fouling of the membrane. A lower normalized flux indicates a higher irreversible fouling and vice versa. As reported in the paper, the untreated sample showed a normalized water flux (i.e., modification grade) of 45%±5%, which is much lower than that found for membranes modified with methylmagnesium bromide, which has a good modification grade of at least 90% for this particular type of substrate. Therefore, the normalized water flux, i.e., modification grade, is a good way to measure the modification grade of this particular type of membrane substrate.

[0118] 10 in the absence of inert gas flow -4A reference sample ("Reference Sample" in Table 2) was obtained by drying the surface of the titania membrane at 190°C and mbar pressure for 16 hours. The titania membrane was the same as the untreated membrane described above. The substrate was then contacted with methylmagnesium bromide (CH3MgBr, abbreviated as C1) (an organometallic reagent having a methyl group as a functional moiety) diluted in THF at a concentration of 0.045 M at room temperature for 24 hours to remove protons and attach at least one functional moiety, thereby obtaining an organofunctionalized titania membrane.

[0119] The normalized water flux of the reference sample was measured following the same method as for the untreated titania membrane, reporting an excellent reforming quality of 94%.

[0120] Example 5 One sample (sample 1 in Table 2) was prepared according to the second embodiment of the present invention. The inorganic substrate was the same as the titania membrane used in Example 4.

[0121] A flow of N2 was used to dry the membrane surface for 12 h at 150° C., followed by the addition of methanol vapor, a proton removal reagent, to the N2 flow for 4 h at 150° C. for combined drying and proton removal. During the combined drying and proton removal step, a flow of 20 l / h of N2+methanol (vapor) was used, where methanol was added to the N2 until the N2 was saturated with methanol.

[0122] The substrate was then contacted with C1 diluted in THF at a concentration of 0.045 M at room temperature for 24 h to obtain an organofunctionalized titania film.

[0123] The normalized water flux was measured as described in Example 4. From Table 2, it is clear that although a lower temperature and no vacuum were used to obtain the organic functionalized titania membrane, the modification quality was in the same range as the reference sample and therefore considered good, thereby reducing the overall energy consumption and therefore the cost of the process.

[0124] Example 6 Three samples (samples 2, 3 and 4 in Table 2) were prepared according to the third embodiment of the present invention. The inorganic substrate was the same as the titania membrane used in Example 4.

[0125] Drying was accomplished by using a flow of N2. Both dry N2 (samples 2 and 3) and humidified N2 (sample 4) were used. The dry N2 contained a maximum of 0.02 ppm water. The flow rate was 20 l / h. The temperature was 200° C. The duration for the dry N2 flow varied between 4 and 16 h, and for the humidified N2 flow it was 16 h.

[0126] The substrate was then contacted with C1 diluted in THF at a concentration of 0.045 M at room temperature for 24 hours to remove protons and attach at least one functional moiety, thereby obtaining an organic functionalized titania membrane. In other words, the combination of proton removal and functionalization was the same as that of the reference sample in Example 4.

[0127] The normalized water flux, i.e., reforming quality, was measured as described in Example 4 using the procedure disclosed in 'Novel grafting method efficiently decreases irreversible fouling of ceramic nanofiltration membranes', G. Mustafa, K. Wyns et al., Journal of Membrane Science 470 (2014) pp. 369-377. From Table 2, it is clear that when the N2 flow is dry, the reforming quality is excellent, and even at a drying time of 4 hours, it is much higher than for the reference sample. However, when the N2 flow is not dry enough, the reforming quality decreases significantly, but is still better than the untreated titania membrane.

[0128] [Table 2] [Explanation of symbols]

[0129] 1. Preparing an inorganic substrate 2 Drying process 3. Proton removal process 4. Purging process 5 Functionalization step 6. Combined drying and proton removal process 7 Single Process 8. Cleaning process 10 First embodiment 20 Second embodiment 30 Third embodiment

Claims

1. A method for producing an organo-functionalized solid inorganic substrate, wherein the surface of the inorganic substrate contains a hydroxide and / or an oxide, and the hydroxide and / or the oxide contains an element M which is a metal or a metalloid, the method comprising: (i) drying the surface; (ii) optionally removing protons from the surface; and (iii) contacting the surface with an organometallic reagent containing at least one organo-functional part, wherein the at least one organo-functional part is bonded to the element M of the hydroxide and / or the oxide by a direct M-C bond not containing an oxygen bridge, thereby obtaining the organo-functionalized inorganic substrate. In the method, the drying step comprises contacting the surface with a flow containing an inert gas and / or dry air.

2. The method according to claim 1, wherein the drying step is carried out at least at atmospheric pressure.

3. The method according to claim 1 or 2, wherein the step of contacting the surface with the flow containing an inert gas is carried out at a temperature of at least 90 °C.

4. The method according to claim 1, wherein the inert gas is selected from the group consisting of nitrogen, noble gases, and mixtures of any two or more thereof.

5. The method according to claim 1, wherein the step of removing protons from the surface comprises contacting the surface with a reagent capable of reacting with protons.

6. The method according to claim 5, wherein the reagent is an alcohol, an organophosphonate ester, an organophosphonic acid ester, an organophosphinic acid, a carboxylic acid or a carboxylate.

7. The method according to claim 5 or 6, wherein the reagent is contacted with the surface as a gas, a vapor, an aerosol or a liquid.

8. The method according to claim 5, wherein the flow containing the inert gas further contains the reagent so as to simultaneously perform the step of drying the surface and the step of removing protons from the surface.

9. The method according to claim 8, wherein the inert gas is bubbled through a liquid bath of the reagent, or the reagent is sprayed in the flow containing the inert gas, thereby obtaining the flow containing the inert gas and the reagent.

10. The method according to claim 1, wherein the step of removing protons from the surface comprises contacting the surface with the organometallic reagent.

11. wherein the organometallic reagent is of the formula R 1 -M 1 、R 1 -M 1 -X or R 1 -M 1 -R 2 [wherein, R 1 and R 2 are organic functional groups, R 1 and R 2 are different or the same, M 1 is Li or Mg, and X is a halogen.], the method according to claim 1.

12. The method according to claim 1, wherein the element M is a Group IVb transition metal, a Group IVa metal or a metalloid.

13. The method according to claim 1, further comprising a washing step.

14. The method according to claim 1, wherein the solid inorganic substrate is a powder, a particle, a shaped substrate, a coated film or a membrane.

15. A method comprising a step of producing an organo-functionalized solid inorganic substrate according to claim 1, and a step of using the organo-functionalized solid inorganic substrate as a film, a catalyst, an adsorbent, a sensor or an electronic component.

16. A method comprising a step of producing an organo-functionalized solid inorganic substrate according to claim 1, and a step of performing a filtration, adsorption, chromatography and / or separation process, wherein the organo-functionalized solid inorganic substrate is used as a substrate in the process.

Images