Method for synthesizing eco-friendly mofs, in particular flexible mofs

Abstract

The invention relates to a method for producing a MOF, wherein a MOF is a structured metal-organic compound comprising a two- or three-dimensional porous network consisting of inorganic entities that are connected by polydentate chelating ligands bonded to multiple metal centers; the polydentate chelating ligands being selected in particular from the group comprising C5-C24 heteroaromatic ligands and aromatic ligands, comprising at least one carboxylic acid function, preferably benzyl or naphthyl di-, tri- or tetracarboxylate, and the aromatic or heteroaromatic ligands optionally bearing, on at least one aromatic ring, a group selected from among -NH2, -OH, -CH3, -NO2, -CF3, -COOH, - SO3H, -SH, -OCH3.

Description

[0001] Title of the invention: Process for the synthesis of eco-compatible MOFs, in particular flexible MOFs

[0002] Description

[0003]

[0001] The present invention is in the field of the synthesis of coordination polymers, and more particularly relates to the preparation of crystallized metal-organic structures, also referred to as structured metal-organic compounds, or MOFs, according to synthesis routes that have not yet been explored, and which are eco-compatible. A compound is said to be eco-compatible when its release into the natural environment is acceptable. An eco-compatible MOF compound does not cause predictable or identifiable malfunctions or significant variation in its ecological balance, and corresponds to a MOF whose preparation, use and end-of-life disposal are environmentally friendly in accordance with the article: “MOFs industrialization: a complete assessment of production costs, Maria Inès Severino, Effrosyni Gkaniatsou, Farid Nouar, Moisés L. Pinto, Christian Serre, Faraday Discuss., 2021, 231, 326”.

[0004] [2] Bibliographic references in the following text are noted in the description text as follows: [] ; and listed in the reference table.

[0005] State of the art

[0006] [3] The preparation and study of metal-organic framework compounds is a field of coordination chemistry in its own right, with clearly identified applications in toxic gas capture [1-5], gas storage [6-7], separation techniques [8-12], small molecule catalysis and electrocatalysis [13-15], heat reallocation [16, 17], water harvesting

[0018] , sensing

[0019] , biological applications

[0020] , etc. In most of the targeted industrial applications, including gas separation, gas storage, heat reallocation, and water harvesting, the targeted MOF must be produced on a very large scale using an environmentally friendly method with minimal energy cost.

[0007] [4] However, the number of MOFs that can be produced in large quantities, on an industrial scale, remains very limited compared to the number of MOFs known to date

[0021] , However, the synthesis routes identified to date for the vast majority of MOFs only use the hydrothermal or solvothermal technique, which technique requires a significant amount of energy impacting the final production cost. This is not compatible with simple methods such as heating at ambient pressure, while allowing the use of green solvents such as the aqueous water / alcohol mixture to be retained or considered

[0022] ,

[0008] [5] Among the different classes of MOFs known, those based on trivalent metal carboxylates, in particular those with Al, are considered the most promising for industrial applications due to their greater hydrolytic stability compared to MOFs based on divalent metal carboxylates [23-26], MIL-53(A1), an Al dicarboxylate, is a reference MOF, very stable and with a flexible framework

[0027] ,

[0009] [6] Considering its high structural flexibility, excellent water stability, this MOF has been studied for a wide range of potential applications such as gas separation [28-30], gas storage

[0031] , catalysis [32, 33], sensing

[0034] , mechanical energy storage

[0035] , nonlinear optics

[0036] etc. It has also been demonstrated that the flexibility of this MOF could be used for CO2 separation (adsorption followed by regeneration) in the presence / absence of external stimulus, such as mechanical pressure

[0037] ,

[0010] [7] Other flexible MOFs of interest are solids of MIL-53 structure but with a functional group on the organic spacer of the MOF: MIL-53(A1)-NH2 and MIL-53(A1)-OH [38-41],

[0011] [8] These flexible MOFs must generally be prepared under hydro- or solvothermal conditions, which are not very compatible with large-scale production. To overcome this drawback, one of the objectives of the present invention is to produce MOFs using an innovative process implementing easy-to-implement techniques, such as heating at ambient pressure, using commercial starting materials and green solvents such as water, alcohols or a mixture thereof.

[0012] [9] Although the synthesis of MIL-53(A1) has been reported using several protocols, whether by room temperature precipitation using water as an environmentally friendly solvent

[0043] , the use of metal salts requires dilute solutions, which significantly reduces the spatio-temporal yield (STY) and makes this process unrealistic from an industrial point of view. Furthermore, to develop flexible aluminum-based MOFs, such as MIL-53(A1), the use of A1(NO3)3.6H2O as the source of Al 3+ entails a significant chemical risk (nitrates) which makes their production on an industrial scale less obvious, which demonstrates that there is a real need to develop alternative synthesis methods.

[0013]

[0010] Although Biswas et al. described a method for synthesizing several functionalized MIL-53(A1) structures starting from AICI3.6H2O

[0044] , this method involves the hydrothermal or solvothermal route, with the aforementioned drawbacks with regard to industrial requirements.

[0014]

[0011] The following syntheses may also be cited as prior art:

[0015] - the synthesis of MIL-53(Fe) and MIL-53(Fe)-NH2 using green solvents such as water as solvent and a water-ethanol mixture as washing solution, but requiring high temperature and pressure conditions (by hydro / solvo-thermal route) [45, 46];

[0016] - the synthesis of a MOF, more precisely In(OH)BDC 0.75BDCH2, in, again, solvothermal conditions in the presence of hydrofluoric acid and / V-A'-di methyl formamide (or so-called DMF), DMF being known in itself as a toxic solvent

[0047] ; and

[0017] - the synthesis, by microwave heating, of MIL-53(X), with X being aluminum or chromium, at ambient pressure

[0048] using a mixture of water and organic solvent (which may be DMF or dimethyl sulfoxide, also called DMSO) and using exclusively DMF as washing solution.

[0018]

[0012] To overcome these drawbacks, one of the objectives of the present invention is to be able to produce MOFs using an innovative process implementing techniques that are easy to implement, such as heating at ambient pressure, from inexpensive commercial constituents and green solvents such as water, (ethyl) alcohol, DMSO or a mixture containing a high proportion of water.

[0019] Description of the invention

[0020]

[0013] The present invention relates to a method for manufacturing a MOF, a MOF being a structured metal-organic compound comprising a two- or three-dimensional porous network consisting of inorganic entities connected by polydentate chelating ligands linked to several metal centers; said polydentate chelating ligands being chosen from the group comprising:

[0021] - C4-C24 aliphatic ligands comprising at least one carboxylic acid function, selected from ligands comprising a linear alkyl chain without unsaturation and ligands comprising carbon chains comprising at least one unsaturation such as fumaric acid or muconic acid;

[0022] - aromatic ligands and heteroaromatic ligands in C4-C24, comprising at least one carboxylic acid function, preferably benzyl or naphthyl di-, tri- or tetracarboxylate, and said aromatic or heteroaromatic ligands, optionally carrying on at least one aromatic nucleus a group selected from -NH2, -OH, -CH3, -OCH3, -NO2, -CF3, -COOH, -SO3H, -SH; said method comprising the following steps: a) dispersing in water a molecule of polydentate chelating ligand, and at least one metal precursor (i.e. at least one metal salt), preferably chosen from metal sulfate salts and metal chlorate salts, preferably an aluminum sulfate salt; b) optionally heat the dispersion obtained in a) to ambient pressure, and maintain it at a temperature of 50 to 150°C, for a period of 10 minutes to 96 hours; c) allow to return to ambient temperature, filter and wash the solid obtained with water;d) drying the solid obtained in c); e) dispersing with stirring the solid obtained in d) in a solution comprising, or even consisting of, DMSO for a period of 30 minutes to 15 hours, at a temperature less than or equal to 150°C.;

[0023]

[0014] The inventors have demonstrated that it is possible to carry out syntheses of MOFs in water, thanks to a subsequent washing step with DMSO making it possible to eliminate untransformed reagents. Conventional synthesis methods usually require carrying out the synthesis (or at least the washing step) in toxic solvents, such as DMF, so that the impurities are eliminated with the washing solvent and do not remain confined in the pores of the MOFs, all while heating the solid for several days in the solution brought to 150°C.

[0024]

[0015] It is specified that, in the above and the following, the terms washing and activation are understood in the same way and can therefore be completely interchangeable.

[0025]

[0016] The inventors have also demonstrated that the use of DMSO during the washing step makes it possible to reduce the time of this step compared to such a washing step carried out with DMF. Indeed, thanks to the relatively higher polarity of DMSO and the better solubility of certain ligands in this solvent - compared to DMF - the unconverted reagents are eliminated more quickly.

[0026]

[0017] In the context of the invention, the term "aromatic group" refers to stable, substituted or unsubstituted, unsaturated mono- or polycyclic hydrocarbon fragments, preferably having 3 to 14 carbon atoms, comprising at least one cycle satisfying Hückel's rule for aromaticity.

[0027]

[0018] The term "heteroaromatic group", as used herein, refers to stable, substituted or unsubstituted monoheterocyclic or polyheterocyclic moieties, preferably having from 3 to 14 carbon atoms, comprising at least one ring satisfying Hückel's rule for aromaticity. Examples of heteroaromatic entities include, but are not limited to, furanyl, pyridinyl (pyridine radical), indolinyl (indole radical), imidazolinyl (imidazole radical), pyrrolinyl (pyrrole radical), quinolinyl, dihydroquinolinyl, isoquinolinyl, quinazolinyl, dihydroquinazolyl and tetrahydroquinazolyl groups. Ligands comprising such a group include 2,5 FDCA: 2,5-furanedicarboxylic acid.

[0028]

[0019] Preferably, the polydentate chelating ligand is selected from at least one type of ligand chosen from a bidendate ligand, a tridentate ligand and a tetradentate ligand, and advantageously comprises C6-C24 aromatic compounds comprising at least one function selected from a carboxylic acid, phosphonic acid, amine, alcohol, ketone and azole function; preferably the polydentate chelating ligand is selected from at least one of the ligands: benzene-1,4-dicarboxylic acid or terephthalic acid (CSHÔC, CAS: 100-21-0, known by the abbreviation 1,4-BDC, BDC, H2-BDC or BDCH2), nitro-terephthalic acid (CSHSNOÔ, CAS: 610-29-7, known by the abbreviation NO2-1,4-BDC), 2-amino-terephthalic acid (C8H5NO4, CAS: 10312-55-7, known by the abbreviation NH2-1,4-BDC), chloro-2-terephthalic acid (C8H5CIO4, CAS: 1967-31-3, known by the abbreviation C1-1,4-BDC), benzene- 1,3, 5 -tricarboxylic acid (CôH CChHTh, CAS: 554-95-0), 3,3',5,5'-azobenzenetetracarboxylic acid (C16H10N2O8, CAS: 365549-33-3), 3,5-pyrazoledicarboxylic acid (C5H4N2O4, CAS: 303180-11-2), 2,5-bistrifluoromethyl-l,4-benzenedicarboxylic acid (C10H4F6O4, CAS: 366008-67-5), 2-(trifluoromethyl)-l,4-benzenedicarboxylic acid (C9H5F3O4, CAS: 1483-47-2), 1,2,4-triazole (C2H3N3, CAS: 288-88- 0), 2-methylimidazole (C4H6N2, CAS: 693-98-1), N,N'- piperazine(methylenephosphonic acid) (C6H16N2O6P2, CAS: 89280-71-7), L-aspartic acid (C4H7NO4, CAS: 56-84-8), 2,5-dihydroxyterephthalic acid (CSOÔHÔ, CAS: 610-92-4) and 3,4-dihydroxy-3-cyclobutene-1,2-dione (C4O4H2, CAS: 2892-51-5).,

[0029]

[0020] Advantageously, the DMSO is removed by rinsing in a step f) of treatment with ethanol after step e).

[0030]

[0021] Preferably, the metal center of the method for manufacturing a MOF according to the invention comprises at least one metal selected from Cu, Zn, Ca, Mg, Ti, Zr, In, Ga, V, Cr, Mn, Fe and Al, preferably the metal is a metal ion selected from at least one metal ion of Fe, Al, Cr and Zr, even more preferably selected from at least one metal ion of Fe, Al, Cr and V.

[0031]

[0022] Preferably, the MOF prepared according to the method of the invention is selected from a MIL-53, a MIL-68, a MIL-69, a MIL-101, a MIP-206, and a DUT-7. Particularly preferably, it is a MOF selected from MIL-53(A1), MIL-53(Fe), MIL-53(Cr), MIL-68(A1), MIL-68(Fe), MIL-68(Cr) and MIP-206(Zr).

[0032]

[0023] Preferably, wherein the MOF is selected from the MIL-53 class comprising a metal ion at the oxidation state +3 of a metal selected from Cr, Al, Fe, V, Ga and In, and the aromatic ligand is benzene-1,4-dicarboxylic acid or a derivative.

[0033]

[0024] Preferably, the benzene-1,4-dicarboxylic acid derivative is benzene-1,4-dicarboxylic acid substituted on the aromatic ring by at least one group chosen from: -NH2, -OH, -CH3, -NO2, -CF3, -COOH, -SO3H, -SH, -OCH3, and preferably a -NH2, -OH and -NO2 group.

[0034]

[0025] Such ligands may for example be NO2-1,4-BDC, NH2-1,4-BDC, or C1-1,4-BDC.

[0035]

[0026] According to the invention, a base may be added during step a), such as sodium hydroxide, piperazine or urea.

[0036]

[0027] Preferably, the metal sulfate used in step a) is A12(SO4)3.16H2O, and preferably urea is added to the dispersion in step a).

[0037]

[0028] Preferably, in which the metal chlorate used in step a) is FeCl3.6H2O.

[0038]

[0029] Preferably, step b) is maintained for 8 hours and 48 hours; and in step e) the dispersion is heated to a temperature less than or equal to 130°C for 1 to 4 hours, with vigorous mechanical stirring.

[0039]

[0030] Another subject of the present invention relates to a MOF of the MIL-53 class, chosen from MIL-53(A1), MIL-53(A1)-NH2, MIL-53(A1)-NO2, MIL-53(A1)-OH, MIL-53(Fe) and MIL-53(Cr), prepared according to the process as described above without the use of DMF, and not involving a calcination step.

[0040]

[0031] Particle size is assessed by imaging, preferably by SEM microscopy.

[0041]

[0032] The present invention also relates to a use of a MOF as described in the context of the present invention for separation (gases, vapors, etc.); in particular the capture of CO2 (postcombustion, precombustion, or biogas); the separation of aromatics (xylenes), aliphatics (branched alkanes); the capture of organovolatile compounds; water-alcohol purification; desalination; materials for batteries; catalysis such as the dehydrogenation of alcohols, or if the MOF is doped or combined with a co-catalyst, for the adsorption and conversion of small molecules (CO2, CH4, NH3, etc.); the management of waste heat, for example by adsorption-flexibility compensation; and detection; separation or storage / release controlled by stimuli such as pressure, electric current, microwave irradiation, and magnetic field.

[0042]

[0033] In the context of the present invention, the BET specific surface area as well as the pore volume were determined by the N2 adsorption method, on the basis of the N2 adsorption-desorption isotherms at -196°C (77K), measured in particular with a device of the Micromeritics® TriStar brand.

[0043]

[0034] Advantageously, a “degassing” step (i.e. heating under vacuum) can be implemented for the preparation of the samples before the sorption isotherm measurement, this step being able to follow step f) mentioned above.

[0044]

[0035] The present invention is also described in the detailed description which follows, using the experimental part which details certain embodiments using examples, given solely for illustrative purposes and which should not be considered as limiting, and the figures briefly described in the part which follows.

[0045] Brief description of the figures

[0046]

[0036] [Fig. l ] - Figure 1 shows the FTIR spectra of MIL-53(A1) (synthesized using SO4 salt) and its activated form in comparison with the free ligand;

[0047]

[0037] [Fig.2] - Figure 2 shows the FTIR spectra of MIL-53(A1)-NO2 (synthesized using SO4 salt) and its activated form in comparison with the free ligand;

[0048]

[0038] [Fig.3] - Figure 3 shows the FTIR spectra of MIL-53(A1)-NH2 (synthesized using SO4 salt) and its activated form in comparison with the free ligand;

[0049]

[0039] [ F ig .4 ] - Figure 4 shows a comparative powder X-ray diffractogram (PXRD plot) of MIL-53-(Al) synthesized from SO4 salt. The sample washed with DMSO and then dried at 100 °C exists mainly in a narrow pore (or np for "narrow pore") configuration as opposed to a large pore (or Ip for "large pore");

[0050]

[0040] [Fi g.5] - Figure 5 shows a comparative FTIR plot of MIL-53 -(Al) synthesized from SO4 salt. Washing with DMSO followed by drying at 100 °C produces a sample of MIL-53 which is free of any ligand inside the pore;

[0051]

[0041] [Fi g.6] - Figure 6 represents a comparative PXRD plot of MIL-53 -(Al) synthesized from chloride salt between a non-activated form and an activated form (dried under vacuum at 100 °C);

[0052]

[0042] [Fig.7] - Figure 7 represents a comparative PXRD plot of MIL-53-(Al)-NO2 synthesized from chloride salt between a non-activated form and an activated form;

[0053]

[0043] [Fig. 8] - Figure 8 represents a comparative PXRD plot of MIL-53-(Al)-NH2 synthesized from chloride salt between a non-activated form and an activated form;

[0044] [Fig. 9] - Figure 9 represents FTIR spectra of MIL-53(A1) and its activated form (synthesized from the chloride salt) in comparison with the ligand;

[0054]

[0045] [Fig. 10] - Figure 10 shows FTIR spectra of MIL-53(A1)-NO2 and its activated form (synthesized from the chloride salt) in comparison with the ligand;

[0055]

[0046] [Fig. 11] - Figure 11 shows FTIR spectra of MIL-53(A1)-NH2 and its activated form (synthesized from the chloride salt) in comparison with the ligand;

[0056]

[0047] [Fig. 12] - Figure 12 represents the thermogravimetric analysis (TGA) curve of MIL-53(A1) (synthesized using SO4 salt) showing the thermal stability of the structure before and after activation;

[0057]

[0048] [Fig. 13] - Figure 13 represents the thermogravimetric analysis (TGA) curve of MIL-53(A1)-NO2 (synthesized using SO4 salt) before and after activation;

[0058]

[0049] [Fig. 14] - Figure 14 represents the thermogravimetric analysis (TGA) curve of MIL-53(A1)-NH2 (synthesized using SO4 salt) before and after activation;

[0059]

[0050] [Fig. 15] - Figure 15 represents the thermogravimetric analysis (TGA) curve of MIL-53(A1) (synthesized using the chloride salt);

[0060]

[0051] [Fig. 16] - Figure 16 represents the thermogravimetric analysis (TGA) curve of MIL-53(A1)-NO2 (synthesized using the chloride salt);

[0061]

[0052] [Fig. 17] - Figure 17 represents the thermogravimetric analysis (TGA) curve of MIL-53(A1)-NH2 (synthesized using the chloride salt);

[0062]

[0053] [Fig. 18] - Figure 18 shows the 77KN2 isotherms of MIL-53(A1) synthesized using a chloride salt. Activation by calcination produces the sample with a slightly lower surface area than activation by DMSO washing;

[0063]

[0054] [Fig. 19] - Figure 19 represents a comparative powder X-ray diffractogram (PXRD plot) of MIL-53(Fe)-Cl;

[0064]

[0055] [Fig.20] - Figure 20 shows the FTIR spectra of MIL-53(Fe)-Cl and its activated form in comparison with the free ligand; and

[0065]

[0056] [Fig.21 ] - Figure 21 represents the thermogravimetric analysis (TGA) curve of MIL-53(Fe)-Cl).

[0066] Experimental Part

[0067]

[0057] Materials and methods

[0068] The reagents used are marketed by the company Alfa Aesar® and used without further purification.

[0058] Instrumentation

[0069] PXRD: Powder X-ray diffraction (PXRD) data were collected using a Bruker® D8 Advance high-throughput diffractometer operating in transmission mode and equipped with a focusing Gobel mirror. The X-ray source was Cu-Ka radiation (X = 1.5418 Å).

[0070]

[0059] Sorption measurement

[0071] All nitrogen porosimetry data were collected on a Micromeritics® TriStar instrument at 77K. CO2 and N2 isotherms at 298K were recorded on a Micromeritics® Triflex instrument. In all cases, measurements were recorded using ultra-high purity gases (grade >4.8). Before adsorption measurement, all samples were degassed at a certain temperature (180-200°C) for 8 hours. Degassing was performed in a single step using a Micromeritics® SmartVacPrep degassing unit: evacuation at 180-200°C on the degassing port (P=10 -6 mbar), the degassing rate then being < 2 pbar / min.

[0072]

[0060] TGA: TGA data were collected on a Mettler Toledo® TGA / DSC 2, STAR System instrument with a heating rate of 5°C / min under oxygen flow.

[0073]

[0061] FTIR: Infrared spectra were measured with a Nicolet iS5 ThermoFisher™ FTIR spectrometer.

[0074]

[0062] Observation of the surface topography of the samples was carried out by scanning electron microscopy (SEM) using an FEI Magellan 400™.

[0075]

[0063] The particle size distribution is carried out using SEM and the particle size measurements are carried out using ImageJ™ software.

[0076]

[0064] In the context of the invention, a mass percentage expressed in % m / m, defines the mass percentage of an ingredient used in the preparation and taken in relation to the total mass of the object considered: a mixture, a material (composite, etc.), a membrane, etc.

[0077] Examples

[0078]

[0065] Part 1: syntheses

[0079] The synthesis of MIL-53(A1), and its derivatives, is optimized using different metal salts such as AICI3.6H2O, A12(SO4)3.16-18H2O, Al(OH)(CH3COO)2.xH2O, A1(OH)3 and NaAlCL in the presence of different bases (NaOH, Urea). Sulfate and chloride salts are reagents of choice for obtaining MIL-53(A1) MOFs. The synthesis methods using these sulfate (Ex.1-3) and chloride (Ex.4-6) salts of said MIL-53 MOFs are described below.

[0066] Example 1:

[0080]

[0067] Preparation of MIL-536AI)

[0081]

[0068] MIL-53(A1) is synthesized using the reflux technique. 100 mmol (66.6 g) of A12(SO4)3.16H2O, 100 mmol (16.6 g) of 1,4-BDC (CAS: 100-21-0) and 100 mmol (6.0 g) of urea are dispersed in 200 ml of water in a 500 ml flask. The mixture is heated to reflux at 120°C and maintained at reflux for 12 hours. After cooling the reaction mixture to room temperature, the colorless powder is filtered and washed with 80 ml of water. The sample is then air-dried overnight. The as-synthesized product contains free 1,4-BDC.

[0082] Free 1,4-BDC is removed from the sample by washing with dimethyl sulfoxide (DMSO):

[0083]

[0069] Activation of MIL-53(A1)

[0084]

[0070] The synthesized MIL-53(A1) powder (22.5g) is suspended in 250ml of DMSO in a 500ml flask. Then the mixture is heated to 120°C with continuous stirring and maintained for about 2 hours under these conditions. After cooling to 50°C, the suspension is centrifuged and washed with ethanol (70ml), then with water (100ml). The product is then dried in an oven at 100°C. The mass of isolated product is 18.5g.

[0085]

[0071] Alternatively, activation can also be carried out by calcining the MIL-53(A1) sample in air, at 330°C for 36 hours. These reaction conditions for activation by high-temperature calcination are not very compatible with implementation on an industrial scale.

[0086]

[0072] Example 2: (outside the invention)

[0087]

[0073] Preparation of MIL-53(A1)-NO2

[0088]

[0074] The synthesis is carried out using the reflux technique. 100 mmol (66.6 g) of A12(SC>4)3.16H2O, 100 mmol (21.1 g) of nitroterephthalic acid (NO2-1,4-BDC, CAS: 610-29-7) and 100 mmol (6.0 g) of urea were dispersed in 200 ml of water in a 500 ml flask. The mixture was then refluxed to 120°C and maintained at reflux for 12 hours. After cooling the reaction mixture to room temperature, the colorless powder was filtered and washed with 80 ml of water. The sample was then air-dried (overnight). The as-synthesized product contains free nitroterephthalic acid. It is removed from the sample by washing with ethanol (EtOH):

[0089]

[0075] Activation of MIL-53(A1)-NO2

[0090]

[0076] The synthesized powder (26.5g) was suspended in 250 ml of EtOH in a 500 ml flask. Then, the mixture was heated to 100°C with continuous stirring and maintained for about 4 hours under these conditions. After cooling to 50°C, the suspension was filtered and then rinsed with ethanol (60 ml). The product was then dried in an oven at 100°C. The mass of isolated product is 22.5 g.

[0091]

[0077] Example 3:

[0092]

[0078] Preparation of MIL-53(A1)-NH2

[0093]

[0079] The synthesis is carried out using the reflux technique. 100 mmol (66.6 g) of Ah(SO4)3.16H2O, 100 mmol (18.1 g) of 2-amino-terephthalic acid (NH2-1,4-BDC, CAS: 10312-55-7) and 100 mmol (6.0 g) of urea were dispersed in 200 ml of water in a 500 ml flask. The mixture was then refluxed to 120°C and maintained at reflux for 12 hours. After cooling the reaction mixture to room temperature, the colorless powder was filtered and washed with 80 ml of water. The sample was then air-dried (overnight). The as-synthesized product contains free 2-amino-terephthalic acid 1,4-BDC.

[0094] Free 2-aminoterephthalic acid is removed from the sample by washing with dimethyl sulfoxide (DM SO):

[0095]

[0080] Activation of MIL-53(A1)-NH2

[0096]

[0081] The synthesized powder (25.5g) is suspended in 250 ml of DMSO in a 500 ml flask. Then the mixture is heated to 120°C with continuous stirring and maintained for approximately 2 hours under these conditions. After cooling to 50°C, the suspension is centrifuged and washed with ethanol (70 ml) and then with water (100 ml). The product was then dried in an oven at 100°C. The mass of isolated product is 19.0 g.

[0097]

[0082] Example 4:

[0098]

[0083] Preparation of MIL-53(A1)

[0099]

[0084] MIL-53(A1) is synthesized using the reflux technique. 150 mmol (36.15 g) of AICh.ôFLO is dissolved in 260 ml of water in a 500 ml flask and the solution was heated to 100°C. Then, 125 mmol (20.75 g) of 1,4-BDC dissolved in 65 ml of 2M NaOH is added to the flask with stirring. Then the mixture was refluxed for 12 hours at 120°C. After that, the colorless gel is filtered and washed with 200 ml of water. The sample is then air-dried (overnight). The mass of isolated product is 23.0 g. The as-synthesized product contains free 1,4-BDC. Free 1,4-BDC is removed from the sample by washing with dimethyl sulfoxide (DMSO):

[0100]

[0085] Activation of MIL-53(A1)

[0101]

[0086] The synthesized powder (23.0 g) is suspended in 250 ml of DMSO in a 500 ml flask. Then the mixture was heated to 120°C with continuous stirring and maintained for about 2 hours under these conditions. After cooling to 50°C, the suspension is centrifuged followed by washing with ethanol (70 ml) then with water (100 ml). The product is dried in an oven at 100°C. The product is then dried in an oven at 100°C. The mass of isolated product is 17.5 g.

[0102]

[0087] Alternatively, activation can also be achieved by calcination. The synthesized MIL-53(A1) powder is finely ground and spread well on a watch glass. Then the watch glass is placed in a programmable furnace. The sample is heated to 330°C (for 2 hours) and maintained at 330°C for 36 hours. After cooling to room temperature, the powder is collected and characterized by PXRD, TGA and IR.

[0103]

[0088] Example 5: (outside the invention)

[0104]

[0089] Preparation of MIL-53(A1)-NC>2

[0105]

[0090] The synthesis is carried out using the reflux technique. 100 mmol (66.6 g) of AICI3.6H2O is dissolved in 250 ml of water in a 500 ml flask and the solution was heated to 100°C. Then, 125 mmol (26.39 g) of nitroterephthalic acid dissolved in 65 ml of 2M NaOH (in a beaker) is added to the flask with stirring. An additional 20 ml of water is added to rinse the beaker. Then the mixture is refluxed for 12 hours at 120°C. After that, the colorless solid is filtered and washed with 150 ml of water and rinsed with 50 ml of ethanol. The sample is then air-dried (overnight). The mass of isolated product is 26.0 g. The product as synthesized contains free nitro-terephthalic acid.

[0106] It is removed from the sample by washing with ethanol (EtOH):

[0107]

[0091] Activation of MIL-53(A1)-NO2

[0108]

[0092] The synthesized powder is finely ground and placed in a 500 ml flask. 250 ml of ethanol are added. The product is refluxed at 100°C for 10 hours and filtered while hot (approximately 60°C) and washed with 40 ml of hot ethanol. The mass of isolated product is 24.25 g-

[0109]

[0093] Note: In some cases, the sample may contain some traces of free ligand after the first wash. In this case, it should be washed once more with 150 ml of ethanol (100°C for 5 hours).

[0110]

[0094] Example 6:

[0111]

[0095] Preparation of MIL-53(A1)-NH2

[0112]

[0096] The synthesis is carried out using the reflux technique. 150 mmol (36.15 g) of AICI3.6H2O is dissolved in 200 ml of water in a 500 ml flask and the solution was heated to 100°C. Then, 125 mmol (22.64 g) of 2-amino-terephthalic acid (NH2-1,4-BDC, CAS: 10312-55-7) dissolved in 120 ml of 2M NaOH (in a beaker) is added to the flask with stirring. 30 ml of water is added to rinse the beaker. Then the mixture is refluxed for 12 hours at 120°C. After that, the yellowish solid is filtered and washed with 200 ml of water and rinsed with 30 ml of ethanol. The sample is then air-dried (overnight). The mass of the isolated product is 19.0 g. The as-synthesized product contains free 2-aminoterephthalic acid NH2-1,4-BDC.

[0113] Free 2-aminoterephthalic acid is removed from the sample by washing with dimethyl sulfoxide (DM SO):

[0114]

[0097] Activation of MIL-53(A1)-NH2

[0115]

[0098] The powder thus synthesized is finely ground and placed in a 500 ml flask. 250 ml of DMSO are added. The mixture is refluxed at 120°C for 2 hours. After cooling to 50°C, the suspension is centrifuged followed by washing with ethanol (70 ml) then with water (100 ml). The product was then dried in an oven at 100°C. The mass of isolated product is 16.2 g.

[0116]

[0099] Example 7:

[0117]

[0100] Preparation of MIL-53(Fe)-Cl

[0118]

[0101] The synthesis is carried out using the reflux technique. 15 mmol (4.10 g) of FeCh.ôEhO and 15 mmol (3.00 g) of 2-chloro-terephthalic acid (C1-1,4-BDC, CAS: 1967-31-3) are dissolved in 120 ml of water in a 250 ml flask. Then the mixture is refluxed for 48 hours. After that, the colorless solid obtained is filtered and washed with 80 ml of water. The sample is then air-dried (overnight). The mass of the isolated product is 3.4 g. The as-synthesized product contains free 2-amino-terephthalic acid 1,4-BDC.

[0119] Free 2-aminoterephthalic acid is removed from the sample by washing with dimethyl sulfoxide (DMSO):

[0120]

[0102] Activation of MIL-53(Fe)-Cl

[0121]

[0103] The powder thus synthesized is finely ground and placed in a 100 ml flask. 50 ml of DMSO are added. The mixture is refluxed at 120°C with stirring for 2 hours. After cooling to 50°C, the suspension is centrifuged followed by washing with ethanol (20 ml) then with water (15 ml). The product was then dried in an oven at 100°C. The mass of isolated product is 3.0 g.

[0122]

[0104] Part 2: analyses and results

[0123]

[0105] Comparison of the FTIR and PXRD spectra in Figures 1 to 11 shows that activation allows the removal of all the free ligand that has not reacted in the MOF synthesis.

[0106] Comparison of the thermogravimetric analysis (TGA) spectra in Figures 12 to 17 also shows that activation allows the removal of all the free ligand that has not reacted in the MOE synthesis.

[0124]

[0107] The gas absorption spectrum shown in Figure 18, shows that activation by calcination produces a MOF MIE-53(A1) with a slightly lower BET surface area than activation by DMSO wash.

[0125] References

[0108] The following table lists the references cited previously in the text:

[0126] [Table 1]

[0127]

[0128]

[0129]

[0130]

Claims

Claims

1. A method of manufacturing a MOF, a MOF being a structured metal-organic compound comprising a two- or three-dimensional porous network consisting of inorganic entities connected by polydentate chelating ligands linked to several metal centers; said polydentate chelating ligands being selected from the group comprising: - C4-C24 aliphatic ligands comprising at least one carboxylic acid function, selected from ligands comprising a linear alkyl chain without unsaturation, and ligands comprising carbon chains comprising at least one unsaturation; - aromatic ligands and heteroaromatic ligands in C5-C24, comprising at least one carboxylic acid function, preferably benzyl or naphthyl di-, tri- or tetracarboxylate, and said aromatic or heteroaromatic ligands, optionally carrying on at least one aromatic nucleus a group selected from -NH2, -OH, -CH3, -OCH3, -NO2, -CF3, -COOH, -SO3H, -SH; said process comprising the following steps: a) dispersing in water a molecule of polydentate chelating ligand, and at least one metal salt, preferably chosen from metal sulfate salts and metal chlorate salts, preferably an aluminum sulfate salt; b) optionally heating the dispersion obtained in a) at ambient pressure, and maintaining it at a temperature of 50 to 150°C, for a period of 10 minutes to 96 hours; c) allow to return to room temperature, filter and wash the solid obtained with water; d) dry the solid obtained in c);e) dispersing with stirring the solid obtained in d) in a solution comprising DMSO for a period of 30 minutes to 15 hours, at a temperature less than or equal to 150°C.;

2. A preparation method according to claim 1, wherein the metal center comprises at least one metal selected from Cu, Zn, Ca, Mg, Ti, Zr, In, Ga, V, Cr, Mn, Fe and Al, preferably the metal is a metal ion selected from at least one metal ion of Fe, Al, Cr and V.

3. Preparation method according to one of claims 1 or 2, wherein the MOF prepared according to the method of the invention is selected from a MIL-53, a MIL-68, a MIL-69, a MIL-101, a MIP-206, and a DUT-7.

4. A preparation method according to any one of claims 1 to 3, wherein the MOF is selected from the MIL-53 class comprising a metal ion in the oxidation state +3 of a metal selected from Cr, Al, Fe, V, Ga and In, and the aromatic ligand is benzene-1,4-dicarboxylic acid or a derivative thereof.

5. A preparation process according to claim 4, wherein the 1,4-benzodicarboxylic acid derivative is 1,4-benzodicarboxylic acid substituted on the aromatic ring by at least one group chosen from: -NH2, -OH and -NO2.

6. Preparation process according to any one of claims 1 to 5, in which the metal sulfate used in step a) is A12(SO4)3.16H2O, and preferably urea is added to the dispersion in step a).

7. Preparation process according to any one of claims 1 to 5, in which the metal chlorate used in step a) is FcCL.ôFLO.

8. Preparation process according to any one of claims 1 to 7, in which step b) is maintained for 8h and 48 hours; and in step e) the dispersion is heated to a temperature less than or equal to 130°C for 1 to 4h, with mechanical stirring.

9. MOF of the MIL-53 class, selected from MIL-53(A1), MIL-53(A1)-NH2, MIL-53(A1)-NO2, MIL-53(A1)-OH, MIL-53(Fe) and MIL-53(Cr), prepared according to the process as described in the preceding claims without the use of DMF, and not involving a calcination step.

10. Use of a MOF according to claim 9, for separation; CO2 capture; separation of aromatics, aliphatics; capture of organo-volatile compounds; water-alcohol purification; desalination; battery materials; catalysis such as dehydrogenation of alcohols; adsorption and conversion of small molecules; waste heat management for example by adsorption-flexibility compensation; detection; and separation or storage / release controlled by stimuli such as pressure, electric current, microwave irradiation, and magnetic field.

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