Preparation of metal-organic frameworks using precursors and crystallization aids

Abstract

Provided herein is a method for producing a metal-organic framework, comprising combining a pre-ligand with a metal source to provide a plurality of solid reactants, adding a solvent to the plurality of solid reactants to form a reaction mixture, heating the reaction mixture, and cooling the reaction mixture to produce a metal-organic framework, wherein at least 50 wt% of the reaction mixture is the plurality of solid reactants, the pre-ligand is converted to a ligand in the reaction mixture, and the ligand reacts with a metal component. The methodology is carried out without the presence of dimethylformamide in the reaction mixture. The method may further comprise adding a crystallization aid, such as zinc oxide, to the reaction mixture.

Description

[Technical field]

[0001] (CROSS-REFERENCE TO RELATED APPLICATIONS) This application claims priority to and the benefit of U.S. Provisional Application No. 63 / 296,178, filed January 4, 2022, and U.S. Provisional Application No. 63 / 202,856, filed June 28, 2021, which are incorporated by reference in their entireties.

[0002] The present disclosure is directed to methods for preparing metal-organic frameworks without the use of dimethylformamide (i.e., in the reaction mixture), and more particularly, to methods for preparing metal-organic frameworks using reaction mixtures of at least 50 wt. % solid reactants and low amounts of solvent. [Background technology]

[0003] Scaling up for commercial production of metal-organic frameworks is challenged by the need for toxic and expensive organic solvents. In some cases, water and / or other low-cost benign solvents can be utilized. However, in many cases, polar aprotic solvents such as dimethylformamide ("DMF") must be used due to the low solubility of the organic ligands. Under such conditions, it is desirable to operate with reaction mixtures that have as high a concentration of reactants as possible. This can be challenging in some reactions, as the resulting materials can exhibit poor crystallinity or lose phase specificity at high concentrations, ultimately limiting the application of the materials. Summary of the Invention

[0004] Provided herein is a method for producing a metal-organic framework, comprising combining a pre-ligand with a metal source comprising a metal component to provide a plurality of solid reactants, adding a solvent to the plurality of solid reactants to form a reaction mixture, heating the reaction mixture, and cooling the reaction mixture to produce an insoluble portion and a soluble portion. At least 50% by weight of the total reaction mixture weight is the plurality of solid reactants. When the reaction mixture is heated, the pre-ligand is converted to a ligand in the reaction mixture, and the ligand reacts with the metal component. The insoluble portion comprises a plurality of metal-organic frameworks. Each metal-organic framework comprises a ligand and a metal component. Each method step is performed without a formamide solvent, and in particular the reaction mixture is free of formamide, e.g., free of dimethylformamide. The method may further comprise the step of adding a crystallization aid to the reaction mixture with the solvent.

[0005] Also provided herein is a method for preparing a metal-organic framework comprising a plurality of tetravalent cations and a plurality of terephthalate linkers, the method comprising the steps of: combining a pre-ligand selected from an ester of terephthalic acid with a metal source comprising a tetravalent metal component to provide a plurality of solid reactants; adding a solvent comprising a monocarboxylic acid, optionally a mineral acid, and optionally a crystallization aid comprising a divalent metal to the plurality of solids to form a reaction mixture having a molar ratio of monocarboxylic acid:(pre)ligand of 1:1 to 20:1; heating the reaction mixture to a temperature between about 100° C. and about 220° C.; cooling the reaction mixture to produce an insoluble portion and a soluble portion; separating the insoluble portion from the soluble portion; and drying the insoluble portion to produce a plurality of metal-organic frameworks. The crystallization aid comprises a divalent metal. The insoluble portion comprises a plurality of metal-organic frameworks. Each metal-organic framework comprises a ligand and a metal component (during heating of the reaction mixture, the pre-ligand is converted to a ligand and the ligand reacts with the metal component). At least 50 wt. % of the total weight of the reaction mixture is a plurality of solid reactants. Each step of the method is carried out without using a formamide solvent, and in particular the reaction mixture is formamide-free, e.g., dimethylformamide-free.

[0006] These and other features and attributes of the disclosed methods of the present disclosure, as well as their advantageous applications and / or uses, will become apparent from the following detailed description. [Brief description of the drawings]

[0007] To assist those of ordinary skill in the relevant art in making and using the subject matter herein, reference is made to the accompanying drawings, in which: [Figure 1] 1 shows powder X-ray diffraction patterns of the samples described in Example 1 (Comparative) and Example 2. [Diagram 2] Figure 1 shows powder X-ray diffraction patterns of UiO-66 metal-organic framework before (upper curve) and after (lower curve) calcination, prepared by the method described in Example 2 using 2 grams of zinc oxide and 20 mL of acetic acid; the arrows point to the unreacted species present in the uncalcined material. [Diagram 3] FIG. 1 is an isotherm of dimethyl terephthalate-derived ("DMT-derived") UiO-66 after water washing and calcination at 250° C. (darkest grey); after formate washing and calcination at 250° C. as described in Example 2 (medium grey); and the comparative method as described in Example 1 (light grey). [Figure 4] FIG. 1 shows the powder X-ray diffraction pattern of UiO-66 synthesized from unpurified post-consumer polyethylene terephthalate ("PET") as described in Example 3. [Diagram 5]FIG. 1 shows the powder X-ray diffraction pattern of a UiO-66 sample prepared using dimethyl terephthalate ("DMT") in the absence of DMF and ZnO crystallization aids, as described in Example 4. [Figure 6] FIG. 1 shows powder X-ray diffraction patterns of UiO-66 samples prepared with DMT and zinc oxide ("ZnO") under different loadings of acetic acid, as described in Example 5. [Figure 7] The powder X-ray diffraction pattern of EMM-32 synthesized at 70°C is shown. [Figure 8] After synthesis, solvent exchange and air drying, powder X-ray diffraction patterns of EMM-32 synthesized at 70° C. and 100° C. are shown. [Figure 9A] The powder X-ray diffraction pattern of EMM-32 that was freeze-dried and then activated at 150°C under vacuum and a scanning electron microscope image of EMM-32 crystals are shown. [Figure 9B] FIG. 1 shows the nitrogen adsorption isotherm of EMM-32 after the metal-organic framework was freeze-dried in benzene and activated at 150° C. for 12 h. [Figure 10] 1 is a thermogravimetric analysis ("TGA") curve for EMM-32 showing decomposition at about 400° C. [Figure 11] The powder X-ray diffraction pattern of EMM-32 synthesized at 100℃ with a ligand concentration of 0.019mol / L. [Figure 12] Powder X-ray diffraction patterns of EMM-32 synthesized at ligand concentrations of 0.035 mol / L and 0.060 mol / L are shown. In each case, the ligand:metal ratio was 1:1 and the reaction temperature was 100°C. [Figure 13A] Powder X-ray diffraction patterns of EMM-32 samples synthesized at concentrations ranging from 0.07 mol / L to 0.17 mol / L with optimized acetic acid / ligand ratios are shown. Note the low signal intensity of the sample synthesized at 0.17 mol / L shown in the top curve. [Figure 13B] The powder X-ray diffraction pattern of EMM-32 synthesized with a ligand concentration of 0.35 mol / L is shown. [Figure 14]The powder X-ray diffraction pattern of EMM-32 synthesized using zinc oxide as a crystallization aid is shown. [Figure 15A] The powder X-ray diffraction pattern of the EMM-32 sample using magnesium oxide as a mediator is shown. [Figure 15B] The powder X-ray diffraction patterns of EMM-32 samples using sodium acetate as a crystallization aid are shown. [Figure 16] Powder X-ray diffraction patterns of 0.35 mol / L EMM-32 samples using zinc chloride and zinc acetate as mediators are shown. [Figure 17] 1 shows the powder X-ray diffraction pattern of EMM-71 synthesized as described in Example 6. [Figure 18] 1 shows the adsorption isotherm performed at 77° C. for EMM-71 synthesized in Example 6. [Figure 19] 1 shows the powder X-ray diffraction pattern of EMM-71 synthesized as described in Example 7. [Figure 20] 1 shows the powder X-ray diffraction pattern of NH2-EMM-71 synthesized as described in Example 8. [Figure 21] 1 shows the powder X-ray diffraction pattern of Zr fumarate synthesized as described in Example 9. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Before the present compounds, components, compositions, and / or methods are disclosed and described, it is to be understood that, unless otherwise specified, the disclosure is not limited to particular compounds, components, compositions, reactants, reaction conditions, ligands, catalyst structures, MOF structures, etc. It is also to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting.

[0009] All numerical values ​​within the detailed description and claims herein are modified by "about" or "approximately" the stated value to account for experimental error and variation.

[0010] For the sake of brevity, only certain ranges are explicitly disclosed herein. However, a range from any lower limit may be combined with any upper limit to describe a range not explicitly described, and similarly, a range from any lower limit may be combined with any other lower limit to describe a range not explicitly described, and similarly, a range from any upper limit may be combined with any other upper limit to describe a range not explicitly described. Furthermore, a range includes every point or individual value between its endpoints, even if not explicitly described. Thus, every point or individual value can be combined with any other point or individual value, or with any other lower or upper limit, to act as its own lower or upper limit, to describe a range not explicitly described.

[0011] For the purposes of this disclosure, the following definitions apply: As used herein, the terms "a" and "the" are understood to encompass the plural as well as the singular.

[0012] As used herein, a "metal-organic framework" may be a mixed metal-organic framework or a metal-organic framework system or a mixed metal mixed organic framework system as described in WO 2020 / 219907.

[0013] As used herein, a ligand (also called a "linker") is a compound that bridges two or more metals (metal nodes) to form the coordination network of a metal-organic framework. The protonation state of a ligand can change during the course of a reaction, and different protonation states of a ligand are collectively referred to as a single ligand.

[0014] As used herein, a pre-ligand or precursor is a compound that participates in a chemical reaction that produces another compound and / or the compound from which a ligand is formed.

[0015] As used herein, the term "divalent" refers to the oxidation state of a divalent cation, not whether it is part of an overall charged molecule (e.g., ZnCl2 is dissolved and not dissociated).

[0016] In compounds described herein that have one or more chiral centers, where the absolute stereochemistry is not specified, it is understood that each center may independently be in the R- or S-configuration, or a mixture thereof. Thus, the compounds provided herein may be enantiomerically pure or may be stereoisomeric mixtures.

[0017] Additionally, in compounds described herein that have one or more double bonds that give rise to geometric isomers that can be defined as E or Z, it is understood that each double bond can independently be E or Z, or a mixture thereof. Likewise, it is understood that in any compound described, all tautomeric forms are also intended to be included.

[0018] In addition, the compounds provided herein may also contain unnatural proportions of atomic isotopes at one or more of the atoms that constitute such compounds. For example, the compounds may contain isotopes of, for example, tritium ( 3 H), Iodine-125( 125 I) or carbon-14 ( 14 C). All isotopic variations of the subject compounds, whether radioactive or not, are intended to be encompassed within the scope of the present disclosure.

[0019] Additionally, the compounds provided herein can include different protonation states depending on the pH of the solution. All conjugate acids and bases of the compounds are intended to be encompassed within the scope of the present disclosure.

[0020] Metal-organic frameworks ("MOFs") are constructed from three-dimensional assemblies of metal ions / metal clusters and organic ligands. With their high pore volume, ordered structure and tunability, metal-organic frameworks are suitable for many applications such as photocatalysis, catalysis, separation and purification, gas / energy storage, and sensing. The high surface area and high concentration of isolated metal ions enhance the gas storage capacity and mass transport.

[0021] Metal-organic frameworks are composed of organic ligands (sometimes called "linkers") bridging metal nodes (called "secondary building blocks" or "SBUs") through coordination bonds, which can self-assemble to form coordination networks. Through equiaxed extension or functionalization of the organic ligand / metal nodes, metal-organic frameworks can be customized for a variety of different applications, ranging from catalytic conversion to adsorption and separation, to biomedical applications. Metal-organic frameworks have properties that are useful for industrial applications such as gas adsorption, gas separation, catalysis, heating / cooling, batteries, gas storage, sensing, and environmental purification.

[0022] The stability of metal-organic frameworks ("MOFs") is due to the strong interactions between low polarizability ions, such as carboxylates, and trivalent metals. Stable metal-organic frameworks are initially formed by the interaction of trivalent cations, i.e. Al 3+ , Fe 3+ , Cr 3+ The first MOFs were based on phthalic acid derived from Zr 4+ , Hf 4+ , Ti 4+Other multivalent cations such as , have been utilized to provide even stronger frameworks. The metal-organic framework UiO-66 was first discovered by reacting zirconium salts with linear dicarboxylic acids. Cavka, JH et al. (2008) "A New Zirconium Inorganic Building Brick Forming Metal Organic Frameworks with Exceptional Stability", J. Am. Chem. Soc., v. 130(42), pp.13850-13851. EMM-71 is a metal-organic framework composed of multiple tetravalent cations and terephthalate linkers, crystallized in a pristine cubic lattice, and characterized by a high number of missing cluster / node defects, and is described in U.S. Provisional Application No. 63 / 202856, filed June 28, 2021.

[0023] In metal-organic frameworks, organic ligands bridge metal nodes (secondary building blocks, SBUs) through coordination bonds, while in MOFs, metal ions form nodes that connect ligands, forming repeating cage-like structures. The resulting hollow structure allows MOFs to offer a large internal surface area.

[0024] In contrast to other porous materials, MOFs further offer unique structural diversity, including uniform pore structures, atomic-level structural uniformity, tunable porosity, and flexibility in a wide variety of network topology, shape, dimensions, and chemical functionality that allows engineering of framework topology, porosity, and functionality. This vast catalog of tunable topologies makes MOFs highly customizable, enabling a wide range of applications from catalytic conversion to adsorption and separations to biomedical applications.

[0025] MOFs consist of both organic and inorganic components in a rigid periodic network structure that is not easily accessible in traditional porous materials, e.g., purely inorganic zeolites. MOFs with various structures can be synthesized depending on the type of metal ions and organic ligands. By creating MOFs with different metal atoms and ligands, materials can be made that selectively absorb specific gases in tailor-made pockets within the structure. Metal-organic frameworks, with their high pore volume, ordered structure, and infinite tunability, have emerged as a new frontier in porous active materials for many applications. However, MOFs are relatively unstable, especially compared to traditional porous silica and alumina.

[0026] Therefore, chemically and thermally stable metal-organic frameworks have been developed using high-valent metals (Al / Cr / Fe 3+ and Zr / Hf / Ti 4+ ), have been developed based on the ZnO-based ...

[0027] The metal-organic framework UiO-66 has been extensively studied for its myriad applications due to its thermal and chemical stability and has been synthesized by many synthetic routes, including continuous flow, mechanochemical, and mainly solvothermal. Outside of a few isolated examples where pre-assembled molecular zirconium clusters were used to direct the synthesis of UiO-66, multiple synthetic conditions involve the reaction of zirconium salts (often chlorides or oxychlorides) with linear dicarboxylic acids. UiO-66 is the prototypic member within the UiO family, composed of terephthalic acid, and was discovered in 2008; see Cavka. Since then, dozens of functionalized derivatives and isorectic analogues (composed of long linear diacids such as 4,4′-biphenyldicarboxylic acid) have been studied. A common theme in the pantheon of synthetic conditions is the use of high-boiling aprotic solvents, with the majority of examples utilizing N,N-dimethylformamide (DMF). Coupled with the use of high boiling aprotic solvents, modifiers in the form of monocarboxylic acids are utilized to increase the reactivity and improve the crystallinity of the resulting materials.

[0028] The synthesis of metal-organic frameworks requires strong solvents such as dimethylformamide (DMF), which has prevented them from being widely commercialized. To date, several approaches have been attempted to circumvent this limitation. For example, alternative synthesis conditions include the use of water dilution to alleviate the need for dimethylformamide (DMF) in the solvent mixture. Another alternative is the use of solubilizing groups such as amino or carboxy groups that can be added to the terephthalic acid ligand to improve solubility. However, this method increases the cost of the starting materials and can reduce the properties of the material, such as reduced crystallinity and reduced intrinsic adsorption selectivity. Other methods include utilizing less toxic solvents, using bio-derived lactones as metal-organic framework precursors, and using depolymerized polyethylene terephthalate ("PET") as the ligand source. See Zhou, L. et al. (2019) "Direct Synthesis of Robust hcp UiO-66 (Zr) MOF Using Poly(ethylene terephthalate) Waste as Ligand Source," Micro. Meso. Mater., v. 290, pg. 109674; Dyosiba, X. et al. (2019) "Feasibility of Varied Polyethylene Terephthalate Wastes as a Linker Source in Metal-Organic Framework UiO-66 (Zr) Synthesis," Ind. Eng. Chem. Res., v.58, pp. 17010-17016. PET contains two main components, namely benzenedicarboxylic acid (BDC) and ethylene glycol, which are building blocks in the synthesis of BDC-based metal-organic frameworks. PET may be extracted by various techniques. BDC obtained from PET waste can be applied in the green synthesis of functional metal-organic frameworks.

[0029] However, even these alternatives suffer from the problem of the need for solvent recovery systems in commercial production lines.Thus, despite efforts to avoid the use of DMF, it remains an important component in the synthesis of metal-organic frameworks.

[0030] Lieb, A. et al. disclose the preparation of large pore vanadium(III) trimesate MIL-100(V) at low solids concentration (about 20 wt%) from a mixture of VCl3 and triethyl-1,3,5-benzenetricarboxylate in water. Lieb, A. et al. (2012) "MIL-100(V) - A Mesoporous Vanadium Metal Organic Framework with Accessible Metal Sites", Micro. Meso. Mater., v.15, pp.48-23.

[0031] The current methodology avoids the need for DMF in the synthesis of metal-organic frameworks containing metal ions of multivalent cations, especially tetravalent cations, such as zirconium, titanium, cerium, and hafnium. The methodology of the present invention also avoids the need for large amounts of solvent by utilizing a pre-ligand (e.g., fumarate or terephthalate ester) that has high solubility in low volumes of solvent (e.g., water or acetic acid, or any component present in liquid form in the reaction mixture described herein). Under reaction conditions, the pre-ligand converts to a ligand (e.g., fumaric acid, terephthalic acid, or derivatives thereof) and reacts with the metal component to form the metal-organic framework. The method of the present invention has the advantage that it is possible to produce metal-organic frameworks without the use of any organic solvents, except for monocarboxylic acids (e.g., acetic acid, and other similar solvents such as formic acid, propionic acid, etc.). Additionally or alternatively, the method of the present invention may use mineral acids (e.g., HCl, and other similar acids such as HBr). The method of the present invention also has the advantage of using less solvent in the synthesis of metal-organic frameworks. In particular, at most one weight equivalent of solvent (including acetic acid, hydrochloric acid, etc., or mixtures thereof, and optionally water) is combined with the solid reactants, as opposed to about 15 to about 35 weight equivalents used in conventional Zr-MOF synthesis. Furthermore, the method of the present invention can provide the ability to operate at high space-time yields, for example, at about 0.4 kg / liter / day (~0.4 kg / L / day) in syntheses having more than 50 wt% solid reactants. In the method of the present invention, a divalent metal source (e.g., zinc oxide) can be added to the synthesis to increase the crystallinity of the metal-organic framework formed and limit the presence of side phases.

[0032] Furthermore, we found that our methodology can utilize post-consumer plastics as acceptable reactants (pre-ligands). This was surprising since literature has reported that these reactants result in denser, lower surface area materials. However, we found that this result was likely due to the high concentration of formic acid and the inclusion of additional organic solvents (e.g., acetone) utilized in the prior art.

[0033] Conventional synthesis method Traditionally, metal-organic frameworks are prepared by the reaction of pre-synthesized or commercially available linkers with metal ions. In an alternative approach, called "in situ linker synthesis", it is possible to generate the organic linker (linker) in situ from the starting material in the reaction medium.

[0034] In the synthesis of metal-organic frameworks, organic molecules are not only structure-directing agents, but also reactants that are incorporated as part of the framework structure. With this in mind, traditional synthesis generally employs elevated reaction temperatures. Solvothermal reaction conditions, structure-directing agents, mineralizing agents, as well as microwave-assisted synthesis and steam-assisted conversion have been recently introduced.

[0035] As mentioned herein, conventional synthesis is typically an application of reactions carried out by conventional electrical heating without parallel reactions. In conventional synthesis, the reaction temperature is the main parameter for the synthesis of metal-organic frameworks, and two temperature ranges are usually distinguished, solvothermal and nonsolvothermal, which determine the type of reaction setup used. Solvothermal reactions are generally carried out in a closed vessel under autogenous pressure, around the boiling point of the solvent used. Nonsolvothermal reactions are carried out at atmospheric pressure, below or at the boiling point, simplifying the synthesis requirements. Nonsolvothermal reactions can be further classified as room temperature and elevated temperature.

[0036] Conventional synthesis of metal-organic frameworks is carried out in a solvent at temperatures ranging from room temperature to about 250°C. Heat is transferred by convection from a high temperature source, an oven. Alternatively, energy can be introduced by electrical potential, electromagnetic radiation, mechanical waves (ultrasound), or mechanically. The energy source is closely related to the time, pressure, and energy per molecule introduced into the system, each of which has a strong influence on the metal-organic framework formed and its morphology. Conventional synthesis methods are described in McDonald, TM et al. (2015) "Cooperative Insertion of CO2in Diamine Appended Metal-Organic Frameworks," Nature, v.519, pp.303-308, and Shearer, GC et al. (2016) "Defect Engineering: Tuning the Porosity and Composition of the Metal-Organic Framework UiO-66 via Modulated Synthesis," Chem. Matter., v.28, pp.3749-3761, both of which are incorporated herein by reference.For additional synthesis of metal-organic frameworks, see McDonald, TM, et al. (2012) "Capture of Carbon Dioxide from Air and Flue Gas in the Alkylamine-Appended Metal-Organic Framework mmen-Mg2(dobpdc)", J. Am. Chem. Soc., v.134, pp.7056-7065; Shearer, GC et al. (2014) "Tuned to Perfection: Ironing Out the Defects in Metal-Organic Framework UiO-66," Chem. Matter., v.26, pp.4068-4071; Cavka, JH et al. (2008) "A New Zirconium Inorganic Building Brick Forming Metal Organic Frameworks with Exceptional Stability" J. Am. Chem. Soc., v.130, pp.113850-13851; Milner, PJ et al. (2018) "Overcoming Double-step CO2 Adsorption and Minimizing Water Co-Adsorption in Bulky Diamine-Appended Variants of Mg2(dobpdc)," Chem. Sci., v. 9, pp. 160-174; further described in U.S. Pat. No. 8,653,292, and U.S. Patent Publication Nos. 2007 / 0202038, 2010 / 0307336, and 2016 / 0031920.

[0037] Synthesis of metal-organic frameworks using preligands Provided herein is a method for producing a metal-organic framework, the method comprising the steps of: (a) combining a pre-ligand with a metal source comprising a metal component to provide a plurality of solid reactants; (b) adding a solvent to the plurality of solid reactants to form a reaction mixture, wherein at least 50% by weight of the reaction mixture is the plurality of solid reactants; (c) heating the reaction mixture, wherein the pre-ligand is converted to a ligand in the reaction mixture and the ligand reacts with the metal component; and (d) cooling the reaction mixture to produce an insoluble portion and a soluble portion; each of steps (a)-(d) is carried out without a formamide solvent, particularly the reaction mixture is free of formamide, such as dimethylformamide, the insoluble portion comprises a plurality of metal-organic frameworks, each metal-organic framework comprising a ligand and a metal component. The method may further comprise the step of adding a crystallization aid to the reaction mixture with the solvent.

[0038] Also provided herein is a method of making a metal-organic framework comprising a plurality of tetravalent cations and a plurality of terephthalate linkers, the method comprising: (a) combining a pre-ligand selected from an ester of terephthalic acid with a metal source comprising a tetravalent metal component to provide a plurality of solid reactants; (b) adding a solvent comprising a monocarboxylic acid and a crystallization aid comprising a divalent metal to the plurality of solids to form a reaction mixture having a molar ratio of monocarboxylic acid:ligand of 1:1 to 20:1; (c) heating the reaction mixture to a temperature between about 100° C. and about 220° C.; (d) cooling the reaction mixture to produce an insoluble portion and a soluble portion; (e) separating the insoluble portion from the soluble portion; and (f) drying the insoluble portion to produce a plurality of metal-organic frameworks. In the method, the metal source comprises a metal component. The insoluble portion comprises a plurality of metal-organic frameworks. Each metal-organic framework comprises a ligand and a metal component. At least 50% by weight of the total weight percent of the reaction mixture is a plurality of solid reactants.

[0039] Each step of the methodology of the present invention (i.e., steps (a)-(d) and (a)-(f), respectively) is carried out without the use of a formamide solvent, particularly dimethylformamide. More specifically, the reaction mixture used in the methodology does not include a formamide solvent, such as dimethylformamide.

[0040] The pre-ligand is a derivative or precursor of a linker (or ligand), such as a fumarate ligand or a terephthalate ligand, which can undergo a reaction, such as hydrolysis or oxidation, to form said ligand, such as fumaric acid, terephthalic acid, or a derivative thereof. More specifically, the pre-ligand may be any 1,4-substituted benzene derivative containing a group, such as a cyano group or an ester group, which can undergo a hydrolysis reaction to obtain terephthalic acid, a deprotonated form of terephthalic acid, or a functionalized derivative thereof. More specifically, the pre-ligand may be a terephthalic acid ester or a derivative thereof, such as polyethylene terephthalate, dimethyl terephthalate, dimethyl 2-amino terephthalate, dimethyl 2-nitro terephthalate, dimethyl 2-chloro terephthalate, dimethyl 2-bromo terephthalate, trimethyl 1,2,4-benzene tricarboxylate, trimethyl 1,3,5-benzene tricarboxylate, and / or tetramethyl 1,2,4,5-benzene tetracarboxylate. Additionally or alternatively, the pre-ligand may be a fumarate ester, such as dimethyl fumarate.

[0041] The metal source includes a metal component. The metal component may be a tetravalent metal such as zirconium, cerium, hafnium, and titanium, or a mixture thereof, preferably Zr or Zr / Hf. Preferably, the metal source may generate the metal component in solution, particularly as a tetravalent cation. Suitable examples of metal sources include, but are not limited to, zirconium tetrachloride, zirconyl chloride, zirconyl nitrate, zirconyl sulfate, cerium ammonium nitrate, cerium nitrate, titanium tetrachloride, titanium oxysulfate, hafnium tetrachloride, hafnium oxychloride, hafnium oxynitrate, or hafnium oxysulfate. In some embodiments, the molar ratio of tetravalent cation:ligand may be between about 1.75:1 and about 1:1.75.

[0042] The solvent used in connection with the process of the present invention is any component present in the reaction mixture in liquid form (e.g., at room temperature under normal pressure). In the process of the present invention, the solvent typically comprises at least one monocarboxylic acid and / or mineral acid, in particular at least one monocarboxylic acid, and optionally water. Suitable examples of monocarboxylic acids include acetic acid (e.g., glacial acetic acid) and its analogues, such as formic acid, propionic acid and mixtures thereof. Suitable examples of mineral acids include hydrochloric acid and its analogues, such as hydrobromic acid.

[0043] The solvent may be added to the reaction mixture in an amount between about 0.1 and about 1.0 weight equivalent relative to the solid reactants. For example, the solvent is added to the reaction mixture in an amount between about 0.1 and about 0.9, about 0.1 and about 0.8, about 0.1 and about 0.7, about 0.1 and about 0.6, about 0.1 and about 0.5, about 0.1 and about 0.4, about 0.1 and about 0.3, or about 0.1 and about 0.2 weight equivalent relative to the solid reactants.

[0044] When the solvent comprises a monocarboxylic acid, the molar ratio of monocarboxylic acid:ligand in the reaction mixture is preferably 1:1 to 20:1, in particular 1:1 to less than 20:1. In this embodiment, the expression "amount of ligand" corresponds to the amount of ligand resulting from the transformation of the preligand during the heating step, for example the amount of fumaric acid or terephthalic acid (or its deprotonated form or functionalized derivative) resulting from the hydrolysis of the corresponding fumaric acid ester or terephthalic acid ester (or its derivative). More specifically, the amount of monocarboxylic acid (e.g. acetic acid) to ligand (expressed as a molar ratio) may be about 20:1, 19:1, 18:1, 17:1, 16:1, 15:1, 14:1, 13:1, 12:1, 11:1 or less, and may be about 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, or 10:1 or more.

[0045] When the solvent comprises a mineral acid instead of or in addition to the monocarboxylic acid, the molar ratio of mineral acid:ligand in the reaction mixture is preferably at most 5: 1. More particularly, the amount of mineral acid (e.g., HCl) to ligand (expressed as a molar ratio) may range from 1:10 to 5:1, or from 1:2 to 3:1, for example from 1:1 to 2:1.

[0046] The crystallization aid may be a divalent metal, in particular a divalent metal selected from the group consisting of zinc, cobalt, tin, copper, and combinations thereof, such as zinc. Preferably, the divalent metal source may generate the divalent metal in solution, in particular as a divalent cation. Suitable divalent metal sources include divalent metal oxides, chlorides, bromides, acetates, formates, oxylates, nitrates, sulfates, and / or their oxyanion salts, such as divalent metal oxides. For example, when the divalent metal is zinc, the divalent metal source may be selected from the group consisting of zinc oxide, zinc chloride, zinc oxychloride, zinc bromide, zinc acetate, zinc sulfate, zinc nitrate, zinc oxynitrate, zinc oxyacid, zinc formate, and mixtures thereof, such as zinc oxide. In one embodiment, the molar ratio of divalent cations to tetravalent cations can be from about 0 to about 5, such as 2 or less, or 1 or less, such as 0.5 or less, and / or at least 0.05, or at least 0.1, such as at least 0.15.

[0047] In the heating step, the reaction mixture is heated at a temperature and for a time sufficient to convert the pre-ligands to ligands and react said ligands with the metal component. The heating step may include heating the sealed reaction mixture at a static condition for at least 4-6 hours. The heating step may also include heating the sealed reaction mixture under dynamic (e.g., stirring, shaking, mixing, agitation) conditions, for example, for up to about 24 hours. The heating step may include heating the sealed reaction mixture in a static or rotating oven between about 70°C and about 180°C. Heating may also be performed without sealing, synthesizing the MOFs under reflux with a solvent at a pressure of about 1 bar. In one embodiment, the reaction mixture is generally heated to 70° C. to 220° C., 100° C. to 220° C., about 70° C. to about 160° C., 100° C. to 160° C., 140° C. to 160° C., about 70° C., about 100° C., about 130° C., about 150° C., or about 160° C., for at least 4 hours to 7 days, or 6 hours to 5 days, or 12 hours to 3 days.

[0048] After cooling, for example to room temperature, an insoluble portion and a soluble portion are produced, the insoluble portion comprising a plurality of metal-organic frameworks. The method may further include separating the insoluble portion from the soluble portion and drying the insoluble portion to produce a plurality of metal-organic frameworks. This may be done by any standard means. For example, the reaction mixture may be centrifuged or filtered to obtain the metal-organic frameworks.

[0049] The method of the invention may further comprise washing the metal-organic framework material separated from the reaction mixture by any standard means, for example, the metal-organic framework material may be washed with solvents such as DMF, methanol, ethanol, acetone and / or water, for example to remove excess organic ligands. The metal-organic framework material may also be washed with a slightly basic solution, for example a borate or formate solution, for example boron borate or boron formate, to remove pendant ligands.

[0050] The method of the invention is particularly suitable for the preparation of zirconium-, titanium-, cerium- and / or hafnium-based metal-organic frameworks, in particular Zr-based (or Zr / Hf-based) metal-organic frameworks, more particularly Zr / Hf-based metal-organic frameworks constructed from polytopic carboxylates. - (or Zr / Hf - ) Metal-organic frameworks, more specifically Zr - (or Zr / Hf - ) terephthalate metal-organic framework and / or Zr - (or Zr / Hf - For example, the method of the present invention can be used to prepare a metal-organic framework selected from the group consisting of UiO-66, EMM-71, Zr-Fumarate, UiO-67, MOF-808, NU-1000, or functionalized derivatives thereof.

[0051] The method of the present invention is advantageous because it reduces the cost and effort required to obtain high quality MOFs, and is economically advantageous because the method takes less time and allows for the synthesis of more material, making more material available for testing and characterization, and requiring significantly less time.

[0052] It is essential that the quality of the MOFs is not sacrificed throughout the scale-up process. Several characterization techniques, detailed below, demonstrate that the novel methods disclosed herein produce MOFs of comparable or superior quality when compared to conventional syntheses.

[0053] Synthesis and characterization of EMM-32 Additionally, described herein is a method for the preparation of EMM-32, a metal-organic framework that exhibits challenging scale-up characteristics. First disclosed in Marshall, RJ et al. "Postsynthetic bromination of UiO-66 analogues: altering linker flexibility and mechanical compliance", Dalton Trans., v.45, 2016, pp. 4132-4135, EMM-32 was discovered as an advanced adsorbent for natural gas, but was subsequently found to exhibit advantageous adsorption properties for the separation of molecules in the lubricant range.

[0054] EMM-32 was synthesized by the solvothermal reaction of commercially available 4,4'-stilbenedicarboxylic acid (SDC) with zirconyl dichloride in dimethylformamide using acetic acid (HOAc) as a reaction modifier. During the optimization of the synthesis, EMM-32 was found to be highly sensitive not only to the reaction conditions but also to the workup and activation.

[0055] Figure 7 shows the X-ray diffraction patterns of EMM-32 synthesis using slight differences in modifier (HOAc) concentration. We found that a molar ratio of HOAc:L of approximately 20:1 was optimal for producing the highest crystallinity in the 70°C synthesis. In fact, going below or above this yielded only small amounts of crystalline EMM-32 and large amounts of amorphous material. This ratio increased as a function of temperature, with an optimum of approximately 40 / 1 (40:1) at 100°C. As with the 70°C case, this optimum modifier to ligand ratio exists within a very narrow window, outside of which amorphous material exists.

[0056] However, we also found that increasing the reaction temperature was essential to produce a material that was stable to activation. Figure 8 shows the powder X-ray diffraction patterns of EMM-32 synthesized at 70 and 100 °C, as synthesized and after solvent exchange and air drying. The as-synthesized sample was left immersed in the protective solvent because of the large background observed. The material grown under the optimal conditions at 70 °C quickly lost much of its order upon solvent exchange and air drying. EMM-32 was also synthesized at 100 °C. In contrast to EMM-32 synthesized at 70 °C, EMM-32 synthesized at 100 °C maintained its crystallinity after solvent exchange and air drying even after 1 day. The synthesis performed at 100 °C maintained its crystallinity after activation and retained much of its crystallinity after 24 hours of exposure to atmospheric moisture.

[0057] In addition to the synthesis conditions, the isolation method was found to be important in obtaining samples with high crystallinity and high surface area. Samples filtered and washed with low boiling point solvents such as acetone generally lose crystallinity, ostensibly due to the rapid evaporation of the solvent from the pore structure. Figure 9A shows the powder X-ray diffraction pattern of EMM-32 lyophilized and activated at 150 °C under vacuum. Figure 9B shows the nitrogen adsorption isotherm of EMM-32 after benzene lyophilization and activation at 150 °C under dynamic vacuum for 12 h. Predicted diffraction peaks shown for the indexed unit cell of EMM-32. All non-indexed peaks correlate to the Cu4331 peak.

[0058] Empirically, it was observed that solvent exchange with a moderately volatile solvent such as acetonitrile, followed by air drying, afforded reasonably crystalline material. However, these materials must be stored under dry conditions, ideally in a nitrogen glove box. For unit cell determination and gas sorption studies, a solvent exchange with benzene was performed. The sample was then heated to 150 °C under vacuum for 12 h to yield simple EMM-32.

[0059] EMM-32 crystallizes in the cubic F432 space group with unit cell dimensions of 30.060 Å as determined by powder X-ray diffraction and adopts an octahedral crystal habit typical of the UiO-66 family of materials. The symmetry in Figure 9A is identical to that reported for the isostructural analogues UiO-66 and UiO-67, as well as identical materials discovered simultaneously in the external literature. For example, Cavka, JH et al. (2008) "A New Zirconium Inorganic Building Brick Forming Metal Organic Frameworks with Exceptional Stability", J. Am. Chem. Soc., v.130(42), pp.13850-13851; Marshall, RJ et al. (2016) "Postsynthetic Modification of Zirconium Metal-Organic Frameworks," Eur. J. Inorg. Chem. 4310-4331. This is almost the same as the unit cell dimensions (30.2 Å) predicted from the UFF4MOF optimized structure generated based on AuToGraFS. Figure 9B shows the nitrogen adsorption isotherm performed at 77 K for the optimally synthesized and activated EMM-32. 2A micropore BET surface area of ​​1.01 m / g was observed with a micropore volume of 1.178 cc / g, which was in agreement with the predicted pore volume from the employed high-throughput simulation system. The discrepancy between the predicted and realized pore volumes is likely due to the inherent inaccuracy of pore volume predictions, as well as imperfections and defects in the material. Zirconium-based UiO-type materials are known to present both linker-missing and node-missing defects, which are highly dependent on the synthesis conditions. For example, Shearer, GC et al. (2014) "Tuning to Perfection: Ironing Out the Defects in Metal-Organic Framework UiO-66," Chemistry of Materials, 14, v.26, pp. 4068-4071; Wu, H. et al. (2013) "Unusual and Highly Tunable Missing-Linker Defects in Zirconium Metal-Organic Framework UiO-66 and Their Important Effects on Gas Adsorption," J. Am. Chem. Chem. Soc. 135, v.28, pp.10525-10532; Gutov, O., et al. (2015) "Metal-Organic Framework (MOF) Defects Under Control: Insights into the Missing Linker Sites and Their Implication in the Reactivity of Zirconium Based Frameworks," Inorg. Chem. v.54(17), pg. 8396. Thermogravimetric analysis (TGA) indicates that these defects are widespread in nature, with evidence by TGA that approximately forty percent (40%) of the linkers are missing from the structure. Figure 10 is a thermogravimetric analysis (TGA) curve of EMM-32 showing decomposition at approximately 400°C. The relative amount of remaining ZrO2 content and organic mass loss indicates the extent of the defects in the structure.

[0060] Current methodological developments Under standard conditions where the molar ratio of modifier to ligand is greater than 20, EMM-32 is poorly crystalline or has a different crystalline phase. In one embodiment, by synthesizing EMM-32 in a unique synthetic regime, we have discovered that it is possible to obtain crystalline samples at concentrations 5-10 times higher than those used in conventional syntheses. However, above a concentration of 0.17 moles of 4,4'-stilbenedicarboxylic acid ("SDC") per liter of solvent, it is possible to obtain crystalline material suitable for scale-up even under optimal conditions.

[0061] To achieve a high solids fraction of reactants in the reaction mixture, the amount of crystallization aid in the reaction mixture provides a material with high crystallinity and good phase selectivity. In one embodiment, zinc compounds have been found to effectively promote the crystallization of metal-organic frameworks, including EMM-32, allowing successful synthesis at concentrations up to (and possibly beyond) 0.52 mol / L.

[0062] Previously, EMM-32 was synthesized under dilute conditions with ligand concentrations below 0.06 mol / L, as shown in Table 1 below. This corresponds to 16 grams per liter of solvent, or 1.6% solid reactant (3% if ZrCl4 is added). Acetic acid, benzoic acid, or hydrochloric acid were used as modifiers (Mod.). When acetic acid was used in the literature, the amount of acetic acid is listed in the "Acetic acid" column. When hydrochloric acid or benzoic acid was used, the molar ratio of modifier to ligand is given in the "Mod:L" column. The superscript number in the "Mod:L" column indicates the modifier used. TIFF2024527540000001.tif80162

[0063] With respect to Table 1, "D" represents the number of days, "[L]" represents the ligand concentration as moles of ligand (SDC) per liter of solvent (DMF + acetic acid + optional water), "[Zr]" represents the zirconium concentration as moles of Zr per liter of solvent (DMF + acetic acid + optional water), and "modifier:L" represents the molar ratio of modifier (acetic acid or benzoic acid) per ligand (SDC).

[0064] During the synthesis studies, it was found that the amount of solid reactants was unacceptably small and little space-time yield could be obtained in a fixed batch reactor with increasing solvent costs. As described herein, it was found that reactions at higher concentrations only work up to a point. For example, when the initial synthesis was operated with an SDC and Zr concentration of 0.019 mol / L, crystalline samples were only obtained at sufficiently high modifier / ligand molar ratios (i.e., 55 and 36 vs. 27 and 9). See Figure 11. However, when similar conditions were used with SDC concentrations of 0.035 mol / L or 0.06 mol / L and modifier to ligand molar ratios between 17.5 and 56, it was found that the resulting material was only partially crystallized. See Figure 12.

[0065] When synthesis was performed with limited HOAc:L (acetic acid / ligand molar ratios from 5.73 to 13.8), crystalline samples could be obtained even at ligand (SDC) concentrations as high as 0.14 mol / L. Figure 13A shows the powder X-ray diffraction patterns of EMM-32 samples synthesized with the optimized acetic acid / ligand molar ratio and ligand concentrations ranging from 0.07 mol / L to 0.17 mol / L. Low signal intensities were obtained for the sample synthesized at 0.17 mol / L. However, above this ratio only partially crystalline material was obtained.

[0066] Typically, crystallinity is improved by increasing the modifier concentration. However, impurities can be formed when high concentrations of reactants are used. Figure 13B shows the powder X-ray diffraction pattern of EMM-32 synthesized at a ligand (SDC) concentration of 0.35 mol / L. As shown in Figure 13B, the materials formed were poorly crystalline. Only with zero acetic acid was a semi-crystalline EMM-32 sample observed. Above that, impurity phases predominated. Addition of modifier did not improve the crystallinity of these materials.

[0067] With this data in hand, we realized that while the unique reaction conditions provided an avenue to achieve a reaction as high as 0.14 mol / L, a method to assist crystallization was needed to obtain even higher concentrations. Unexpectedly, zinc oxide (not expected to interact or entrap within the framework) was able to effectively assist crystallization, at least doubling the reaction concentration. For example, Figure 14 shows powder X-ray diffraction patterns for EMM-32 samples synthesized using zinc oxide as a crystallization aid at ligand concentrations ranging from 0.17 to 0.54 mol / L. All reactions were performed at a 10 mL scale (vs. DMF). The amount of acetic acid in each sample was independently optimized. Different amounts of zinc oxide were added to these reactions and were found to yield crystalline samples. Similar to the metal-free synthesis, the ideal acetate to ligand molar ratio was low compared to the prior art and decreased to lower values ​​at higher concentrations.

[0068] Surprised by this result, we attempted to isolate the effect of the presence of zinc cations, which form during the reaction from the reaction of ZnO with SDC and acetic acid. To test this, we screened the effect of magnesium oxide on the synthesis of EMM-32. As shown in Figure 15A, when the same 0.35 mol / L reaction that was successful with ZnO was attempted with an equimolar amount of magnesium oxide, a poorly crystalline sample was obtained. Similarly, when an equivalent amount of acetic acid (assumed to form from the reaction of ZnO with acetic acid) was added, poor quality material was observed; see Figure 15B.

[0069] Since simple basic oxides and salts such as magnesium oxide and sodium acetate are unable to aid in the crystallization of EMM-32, it is believed that the zinc cation itself plays the role of a mediator for crystallization. To test this, zinc acetate or zinc chloride were used as mediators. As can be seen in Figure 16, the addition of zinc acetate appeared to be equally effective in aiding the crystallization of EMM-32. Also, the material made in the presence of zinc chloride showed a significantly higher degree of crystallinity compared to the sample made without the presence of salt. Furthermore, the material made by the method of the present invention does not show the same amount of sensitivity observed when the material was originally made, even without special activation. The metal-organic framework was found to be stable and did not degrade over time.

[0070] The aspects of the present disclosure will be described in more detail by specific examples.The following examples are provided for illustrative purposes and are not intended to limit the present disclosure in any manner.Those skilled in the art in the relevant technical field can easily recognize that various parameters can be changed or modified to obtain essentially the same results. EXAMPLES

[0071] Features of the present disclosure are illustrated in the following non-limiting examples.

[0072] In these examples, X-ray diffraction (XRD) patterns of the materials were recorded in the 2θ range of 2 to 60° using either a Panalytical XPert Pro powder X-ray diffractometer fitted with an Anton Parr HTK-16N environmental stage equipped with platinum strip heaters, or a Bruker D8 Envdevor instrument in continuous mode using copper Kα radiation, Bragg-Bentano geometry, equipped with a Lynxeye detector. In both cases, interplanar spacing, d-spacing, was calculated in angstroms. Intensities are uncorrected for Lorentz and polarization effects. The positions of the diffraction peaks in 2θ, and the relative peak area intensities of the lines, I / I(o), where Io is the intensity of the line stronger than the background, were determined with the MDI Jade peak fitting algorithm using a third order polynomial background fit. It should be understood that diffraction data described as single lines may, under certain conditions, such as differences in crystallographic changes, consist of multiple overlapping lines that appear as resolved or partially resolved lines. Typically, crystallographic changes involve minor changes in unit cell parameters and / or changes in crystal symmetry, without altering framework connectivity. These minor effects, including changes in relative intensity, may also result from differences in cation content, framework composition, the nature and degree of pore filling, crystal size and shape, preferred orientation, and thermal and / or hydrothermal history. All samples were analyzed as is, without further polishing.

[0073] Relative intensity is measured by the method of Shearer, GC et al., Defect Engineering: Tuning the Porosity and Composition of the Metal-Organic Framework UiO-66 via modulated Synthesis, Chem. Mater., v.28(11), pp.3749-3761, 2016. Relative intensity characterizes the degree of defects in the framework, especially nodal defects. As detailed in Shearer et al., the relative intensity of broad peaks (i.e., between 3 and 7° 2θ), for example in the UiO-66 framework, is a quantitative descriptor of the concentration of missing cluster defects in the framework. The relative intensity is calculated as the integrated intensity of the broad peak (near 5° 2θ, e.g., between 2° and 7° 2θ, i.e., corresponding to the total integrated intensity of the (100) peak and the (110) peak in the present invention) divided by the average of the intensities of the (111), (200) and (600) peaks, which correspond to peaks at approximately 7.4, 8.5 and 25.8° 2θ, respectively. TIFF2024527540000002.tif18131

[0074] The peak width ratio is the ratio of the calculated half-widths (as calculated by the MDI Jade peak fitting algorithm) of the (110) and (111) peaks occurring below 6 and 7.4° 2θ.

[0075] Scanning electron microscopy (SEM) images of the as-synthesized materials were obtained on a Hitachi 4800 scanning electron microscope.

[0076] The total surface area of ​​a material (BET surface area or S BET ) was measured using nitrogen adsorption-desorption at liquid nitrogen temperature as described by S. Brunauer, PH Emmett and E. Teller, J. Am. Chem. Chem. Soc., 1938, v.60, pg.309. The external surface area (S ext ) is obtained from the t-plot method and the micropore surface area (Smicro ) is the total BET surface area (S BET ) to the external surface area (S ext ) was calculated by subtracting

[0077] The total pore volume and micropore volume of a material can be determined using methods known in the relevant art. For example, the porosity of a material can be measured by nitrogen physisorption and the data can be analyzed by the t-plot method described in Lippens, BC et al., "Studies on pore systems in catalysts: V. t method", J. Catal., v.4, pg. 319 (1965).

[0078] Thermogravimetric analysis (TGA) was performed by heating from room temperature to 800°C in air.

[0079] High pressure CH4 adsorption was measured using a Hidden Volumetric gas adsorption analyzer (Kortunov, et al., 2016).

[0080] Example 1: Synthesis of UiO-66 for naphthalene separation (comparative example) 66.375 grams (400 millimoles ("mmol") of terephthalic acid and 92.25 grams (297 mmol) of zirconyl chloride octahydrate (ZrOCl2·8H2O) were charged to a round-bottom flask along with 937 mL of dimethylformamide (DMF) and 573 mL of glacial acetic acid (HOAc: L = 24.21) and heated to 120 °C for 16 hours. The resulting product was centrifuged and washed three times ("3x") with DMF (200 mL each), followed by two solvent washes with acetone (2x 200 mL). The resulting acetone-wet solid was allowed to air dry. Figure 1 shows the X-ray diffraction pattern of a sample prepared by this method.

[0081] Example 2: Use of Dimethyl Terephthalate ("DMT") to Form UiO-66 Without the Use of Dimethylformamide ("DMF") 25 grams of dimethyl terephthalate ("DMT", 127 mmol) and 41.25 grams of zirconyl chloride octahydrate (ZrOCl2·8H2O, 128 mmol) were charged to a 125 mL Teflon-lined Parr reactor. Zinc oxide (0–6 grams [0–74 mmol]) was added, followed by 16–24 mL of acetic acid (molar ratio HOAc:DMT = 2.15–3.30). The reaction mixture was mixed manually to homogenize, sealed, and heated to 140°C–160°C for 16 hours and cooled. The insoluble material was then extracted from the reactor, suspended in 300 mL of water, and heated between room temperature and 100°C for 5–240 minutes. The metal-organic framework was isolated and optionally washed with additional water. The metal-organic framework was then solvent exchanged with a low boiling point solvent such as acetone. The metal-organic framework was air-dried and optionally calcined at 150°C to 350°C.

[0082] After washing with water, some impurity peaks were observed in the X-ray diffraction pattern. Several impurity peaks are observed in the X-ray diffraction pattern ("PXRD") of the obtained metal-organic framework (Figure 2, upper curve), which can be removed by calcination (Figure 2, lower curve).

[0083] As shown in FIG. 3, the gas adsorption of the sample prepared according to this example (water or formate washed, then calcined at 250°C (darkest and medium grey curves, respectively)) was compared to the sample prepared according to the comparative method of Comparative Example 1 (light grey curve). A more pronounced feature is observed in the sample prepared via Example 2 and at 0.0001 P / P0, followed by a more gradual increase in adsorption in the pressure range of 0.001 to 1 P / P0. This feature indicates a relatively low level of node and / or ligand defects.

[0084] Example 3: Use of post-consumer polymers as starting materials 312 milligrams ("mg") of polyethylene terephthalate (PET) plastic chip (cm 2) was added to a 23 mL Parr reactor along with 298 mg of zirconium tetrachloride. 200 microliters ("μL") of acetic acid was added and the reactor was heated to 160° C. for 16 hours. The reactor was cooled and the solid was washed with water, then acetone, and air-dried. The resulting brown powder was analyzed by PXRD and found to be phase pure UiO-66, as shown in FIG. 4.

[0085] Example 4: Use of DMT to form UiO-66 without the use of DMF or ZnO Dimethyl terephthalate ("DMT") and ZrOCl2 hydrate were charged to a 10 CC autoclave and acetic acid was added (0-500 μL). The reaction mixture was sealed and heated at 150 °C overnight. After cooling to room temperature, the samples were analyzed by X-ray diffraction. As shown in Figure 5, samples with less than 150 μL of acetic acid showed an impurity peak at 7° 2θ, while samples with 150 μL or more of acetic acid showed the presence of an impurity peak at 9.5° 2θ. These impurities are soluble in water and can be removed by further washing the material with water, resulting in a lower yield of UiO-66.

[0086] Example 5: UiO-66 prepared using DMT and ZnO without DMF 312 mg of dimethyl terephthalate (DMT), 414 mg of zirconyl chloride, and 25-50 mg of zinc oxide was added to a Parr 25 mL autoclave. 50-300 μL of acetic acid was added and the reaction was heated to 150 °C for 12-15 h. Compared to Example 4, the formation of the impurity at 9.5° 2θ is effectively suppressed by the presence of zinc oxide in the recipe at higher acetic acid concentrations (e.g., 150 to 300 μL of HOAc). See Figure 6.

[0087] Example 6: Synthesis of EMM-71 using DMT and HCl without DMF 18 g of dimethyl terephthalate was added to a 125 mL autoclave along with 29.64 g of zirconium oxychloride. 14.4 mL of acetic acid and 8.64 mL of hydrochloric acid were added and mixed with a spatula. The autoclave was sealed and heated to 150 °C over 0-8 hours and held at 150 °C for 5-10 hours. The autoclave was then cooled. The solids (the insoluble portion of the reaction mixture) were suspended in water and isolated by filtration. The insoluble portion was then washed with dimethylformamide at 70 °C and isolated again by filtration. These solids were then washed with 0.25 M aqueous sodium formate at 80 °C, isolated by filtration, and the filter cake was washed with water and then acetone. Figure 17 shows the PXRD pattern of the resulting EMM-71 metal-organic framework. Figure 18 shows the adsorption isotherm performed at 77 °C for the synthesized EMM-71. The surface area was 1700 m 2 / g.

[0088] Example 7: Synthesis of EMM-71 at low temperature using DMT and HCl without DMF 25 g of dimethyl terephthalate was added to a 125 mL autoclave along with 41.17 g of zirconium oxychloride. 20 mL of acetic acid and 12 mL of hydrochloric acid were added and mixed with a spatula. The autoclave was sealed and heated to 120°C over 0-8 hours and held at 120°C for 5-10 hours. This can optionally be done with tumbling in an oven. The autoclave was heated for 14-18 hours and then cooled. The solids (the insoluble portion of the reaction mixture) were suspended in water and isolated by filtration. The insoluble portion was then washed with dimethylformamide at 70°C and again isolated by filtration. These solids were then washed with 0.25 M aqueous sodium formate at 80°C, isolated by filtration, and the filter cake was washed with water and then acetone. Figure 19 shows the powder X-ray diffraction pattern of EMM-71 synthesized as described in this example.

[0089] Example 8: Functionalized NH without DMF 2 EMM-71(NH 2 Synthesis of -EMM-71 1.45 grams of dimethyl 2-aminoterephthalate, 2.635 grams of zirconium oxychloride and 0.84 grams of hafnium oxychloride were charged into a 23 mL autoclave. 0.8–1.2 mL of acetic acid and 0.7–1.1 mL of concentrated hydrochloric acid were added. The mixture was homogenized to a paste and heated to 120–150 °C over 0–8 hours and held at 120–150 °C for 5–10 hours. The solid was then suspended in water and isolated by filtration or centrifugation. The solid was optionally washed with dimethylformamide and / or acetone. The solid was dried to obtain yellow NH2-EMM‐71. X-ray photographs of samples prepared under different solvent conditions are shown in Figure 20. The relative intensities of the samples from the bottom to the top are 0.88, 1.0, 2.5, 1.1, and 1.1, respectively. The peak width ratios from bottom to top are 2.56, 3.02, 1.94, 2.17, and 2.47.

[0090] Example 9: Synthesis of Zr-Fumarate using dimethyl fumarate without using DMF 3.5 g of a solid mixture of dimethyl fumarate, zirconium oxychloride, and hafnium oxychloride (weight ratio of dimethyl fumarate:ZrOCl2·8H2O:HfOCl2·8H2O=1:1.85:0.48) was added to a 23 mL Teflon-lined autoclave. 0.5-1 mL of concentrated hydrochloric acid was added, followed by 0.8-1.4 mL of acetic acid. The reaction was sealed and heated to 120-150 °C over 0-8 hours and then held at that temperature for 5-10 hours. The solid was then suspended in water and isolated by filtration or centrifugation. The solid was optionally washed with dimethylformamide and / or acetone. The solid was dried to obtain white zirconium fumarate. X-rays of a sample prepared according to Example 9 are shown in Figure 21. In this case, no defects were formed and the relative intensity and peak ratio values ​​are not calculated.

[0091] Additionally or alternatively, the present invention relates to: EMBODIMENT 1 combining the pre-ligand with a metal source comprising a metal component to provide a plurality of solid reactants; adding a solvent to a plurality of solid reactants to form a reaction mixture; heating the reaction mixture; and Cooling the reaction mixture to produce an insoluble portion and a soluble portion. Including, At least 50% by weight of the reaction mixture is a plurality of solid reactants; The pre-ligand is converted to a ligand in the reaction mixture, and the ligand reacts with the metal component; The method for preparing a metal-organic framework, wherein the reaction mixture is free of dimethylformamide, and the insoluble portion comprises a plurality of metal-organic frameworks, each metal-organic framework comprising a ligand and a metal component.

[0092] EMBODIMENT 2 2. The method of embodiment 1, wherein the pre-ligand is a fumarate ester or a terephthalate ester.

[0093] EMBODIMENT 3 3. The method according to embodiment 2, wherein the pre-ligand is selected from the group consisting of dimethyl fumarate, dimethyl terephthalate, dimethyl 2-aminoterephthalate, dimethyl 2-nitroterephthalate, dimethyl 2-chloroterephthalate, dimethyl 2-bromoterephthalate, trimethyl 1,2,4-benzenetricarboxylate, trimethyl 1,3,5-benzenetricarboxylate, tetramethyl 1,2,4,5-benzenetetracarboxylate, polyethylene terephthalate, and mixtures thereof, preferably dimethyl fumarate, dimethyl terephthalate, dimethyl 2-aminoterephthalate, and / or polyethylene terephthalate.

[0094] EMBODIMENT 4 4. The method of any one of the preceding claims, wherein the metal component is a tetravalent metal selected from the group consisting of zirconium, titanium, cerium, hafnium, and combinations thereof, preferably zirconium, or a mixture of zirconium and hafnium, more preferably zirconium.

[0095] EMBODIMENT 5 4. The method according to any one of the preceding claims, wherein the metal-organic framework is a zirconium-based metal-organic framework or a zirconium-based metal-organic framework further comprising hafnium, preferably a zirconium-based metal-organic framework.

[0096] EMBODIMENT 6 6. The method according to any one of the preceding embodiments, wherein the solvent comprises at least one of a monocarboxylic acid and / or a mineral acid, and optionally water, preferably the solvent comprises at least a monocarboxylic acid.

[0097] EMBODIMENT 7 7. The method of embodiment 6, wherein the monocarboxylic acid is selected from the group consisting of acetic acid, formic acid, propionic acid, and mixtures thereof, preferably acetic acid, more preferably glacial acetic acid.

[0098] EMBODIMENT 8 8. The method according to embodiment 6 or 7, wherein the mineral acid is selected from the group consisting of hydrochloric acid, hydrobromic acid, and mixtures thereof, preferably hydrochloric acid.

[0099] EMBODIMENT 9 9. The process according to any one of embodiments 6 to 8, wherein the amount of monocarboxylic acid, in particular acetic acid, to ligand in the reaction mixture is from 1:1 to 20:1 in molar ratio.

[0100] EMBODIMENT 10 10. The process according to any one of embodiments 6 to 9, wherein the amount of mineral acid, in particular HCl, to ligand in the reaction mixture is at most 5:1, expressed as a molar ratio.

[0101] EMBODIMENT 11 11. The method of any one of the preceding embodiments, wherein the solvent is added to the reaction mixture in an amount of 0.1 to 1.0 weight equivalents relative to the solid reactants.

[0102] EMBODIMENT 12 12. The method of any one of the preceding embodiments, further comprising adding a crystallization aid to the reaction mixture with the solvent.

[0103] EMBODIMENT 13 13. The method of embodiment 12, wherein the crystallization aid is a divalent metal selected from the group consisting of zinc, cobalt, tin, copper, and combinations thereof, preferably zinc.

[0104] EMBODIMENT 14 14. The method of embodiment 13, wherein the divalent metal source is a divalent metal oxide, chloride, bromide, acetate, formate, oxalate, nitrate, sulfate, and / or an oxyanion salt thereof, preferably a divalent metal oxide, in particular zinc oxide.

[0105] EMBODIMENT 15 15. The method of any one of the preceding embodiments, wherein the reaction mixture is heated to a temperature between about 100° C. and 220° C.

[0106] EMBODIMENT 16 16. The method of any one of the preceding embodiments, wherein the metal-organic framework is a Zr-terephthalate metal-organic framework or a Zr-fumarate metal-organic framework.

[0107] EMBODIMENT 17 17. The method according to any one of the preceding claims, wherein the metal-organic framework is selected from UiO-66, EMM-71, zirconium fumarate, MOF-808, NU-1000, or functionalized derivatives thereof, preferably selected from UiO-66, EMM-71, and zirconium fumarate.

[0108] EMBODIMENT 18 Separating the insoluble portion from the soluble portion, and / or drying the insoluble portion to produce a plurality of metal-organic frameworks. 18. The method of any one of embodiments 1 to 17, further comprising:

[0109] EMBODIMENT 19 combining a pre-ligand selected from an ester of terephthalic acid with a metal source comprising a tetravalent metal component to provide a plurality of solid reactants; adding a solvent comprising a monocarboxylic acid and a crystallization aid comprising a divalent metal to the plurality of solids to form a reaction mixture having a molar ratio of monocarboxylic acid:ligand of 1:1 to 20:1; heating the reaction mixture to a temperature between about 100° C. and about 220° C.; cooling the reaction mixture to produce an insoluble portion and a soluble portion; separating the insoluble portion from the soluble portion; and drying the insoluble portion to produce a plurality of metal-organic frameworks; Including, At least 50% by weight of the reaction mixture is a plurality of solid reactants; the insoluble portion comprises a plurality of metal-organic frameworks, each metal-organic framework comprising a ligand and a metal component; A method for preparing a metal-organic framework comprising a plurality of tetravalent cations and a plurality of terephthalate linkers, wherein the reaction mixture is free of dimethylformamide.

[0110] EMBODIMENT 20 20. The method of embodiment 19, wherein the pre-ligand is selected from the group consisting of dimethyl terephthalate, dimethyl 2-amino terephthalate, dimethyl 2-nitro terephthalate, dimethyl 2-chloro terephthalate, dimethyl 2-bromo terephthalate, trimethyl 1,2,4-benzenetricarboxylate, trimethyl 1,3,5-benzenetricarboxylate, tetramethyl 1,2,4,5-benzenetetracarboxylate, polyethylene terephthalate, and mixtures thereof, preferably dimethyl terephthalate, dimethyl 2-amino terephthalate, and / or polyethylene terephthalate.

[0111] EMBODIMENT 21 21. The method of embodiment 19 or 20, wherein the tetravalent metal component is selected from the group consisting of zirconium, hafnium, and combinations thereof.

[0112] EMBODIMENT 22 22. The method according to any one of embodiments 19 to 21, wherein the monocarboxylic acid is selected from the group consisting of acetic acid, formic acid, propionic acid, and mixtures thereof, preferably acetic acid, more preferably glacial acetic acid.

[0113] EMBODIMENT 23 23. The method of any one of embodiments 19-22, wherein the crystallization aid is zinc oxide.

[0114] EMBODIMENT 24 24. The method of any one of embodiments 19 to 23, wherein the reaction mixture is heated to a temperature between about 100° C. and 220° C.

[0115] EMBODIMENT 25 25. The method of any one of embodiments 19 to 24, wherein the metal-organic framework is selected from UiO-66, EMM-71, zirconium fumarate, MOF-808, NU-1000, or functionalized derivatives thereof, preferably selected from UiO-66, EMM-71, and zirconium fumarate.

[0116] Numerous changes, modifications, and variations will be apparent to those of ordinary skill in the art in light of the foregoing description without departing from the spirit or scope of the present disclosure, and where numerical lower and upper limits are listed herein, ranges from any lower limit to any upper limit are contemplated.

Claims

1. providing a plurality of solid reactants by combining a pre-ligand with a metal source containing a metal component; adding a solvent to the plurality of solid reactants to form a reaction mixture; heating the reaction mixture; and cooling the reaction mixture to produce an insoluble portion and a soluble portion comprising: at least 50% by weight of the reaction mixture being the plurality of solid reactants; the pre-ligand being converted to a ligand in the reaction mixture, and the ligand reacting with the metal component; the reaction mixture not containing dimethylformamide, and the insoluble portion containing a plurality of metal-organic frameworks, each metal-organic framework containing a ligand and a metal component, a method for producing a metal-organic framework.

2. The method according to claim 1, wherein the pre-ligand is a fumaric acid ester or a terephthalic acid ester.

3. The method according to claim 2, wherein the pre-ligand is selected from the group consisting of dimethyl fumarate, dimethyl terephthalate, dimethyl 2-aminoterephthalate, dimethyl 2-nitroterephthalate, dimethyl 2-chloroterephthalate, dimethyl 2-bromoterephthalate, trimethyl 1,2,4-benzenetricarboxylate, trimethyl 1,3,5-benzenetricarboxylate, tetramethyl 1,2,4,5-benzenetetracarboxylate, polyethylene terephthalate, and mixtures thereof.

4. The method according to claim 1, wherein the metal component is a tetravalent metal selected from the group consisting of zirconium, titanium, cerium, hafnium, and combinations thereof.

5. The method according to claim 1, wherein the metal-organic framework is a zirconium metal-organic framework or a zirconium-based metal-organic framework further containing hafnium.

6. The method according to claim 1, wherein the solvent contains at least one of a monocarboxylic acid and / or a mineral acid.

7. The method according to claim 6, wherein the monocarboxylic acid is selected from the group consisting of acetic acid, formic acid, propionic acid, and mixtures thereof.

8. The method according to claim 6, wherein the mineral acid is selected from the group consisting of hydrochloric acid, hydrobromic acid, and mixtures thereof.

9. The method according to claim 7, wherein the solvent contains a monocarboxylic acid, particularly acetic acid, and the amount of the monocarboxylic acid, particularly acetic acid, relative to the ligand in the reaction mixture is in a molar ratio of 1:1 to 20:

1.

10. The method according to claim 1, wherein the solvent is added to the reaction mixture in an amount of 0.1 to 1.0 weight equivalents relative to the solid reactant.

11. The method according to claim 1, further comprising adding a crystallization aid to the reaction mixture together with the solvent, wherein the crystallization aid is a divalent metal selected from the group consisting of zinc, cobalt, tin, copper, and combinations thereof.

12. The method according to claim 11, wherein the divalent metal source is a divalent metal oxide, chloride, bromide, acetate, formate, oxalate, nitrate, sulfate, and / or an oxyanion salt thereof, preferably a divalent metal oxide.

13. The method according to claim 1, wherein the reaction mixture is heated to a temperature between 100°C and 220°C.

14. The method according to claim 1, wherein the metal-organic framework is a Zr-terephthalate metal-organic framework or a Zr-fumarate metal-organic framework.

15. The method according to claim 1, wherein the metal-organic framework is selected from UiO-66, EMM-71, zirconium fumarate, MOF-808, NU-1000, or a functionalized derivative thereof.

16. Separating the insoluble portion from the soluble portion, and / or Drying the insoluble portion to produce a plurality of metal-organic frameworks The method according to claim 1, further comprising.

17. Providing a plurality of solid reactants by combining a pre-ligand selected from esters of terephthalic acid with a metal source containing a tetravalent metal component; Adding a solvent containing a monocarboxylic acid and a crystallization aid containing a divalent metal to the plurality of solids to form a reaction mixture having a monocarboxylic acid:ligand molar ratio of 1:1 to 20:1; Heating the reaction mixture to a temperature between 100°C and 220°C; Cooling the reaction mixture to produce an insoluble portion and a soluble portion; Separating the insoluble portion from the soluble portion; and Drying the insoluble portion to produce a plurality of metal-organic frameworks, Comprising At least 50% by weight of the reaction mixture is a plurality of solid reactants, The insoluble portion contains a plurality of metal-organic frameworks, and each metal-organic framework contains a ligand and a metal component, The method according to claim 1, wherein the reaction mixture does not contain dimethylformamide.

18. The method according to claim 17, wherein the crystallization aid is zinc oxide.

19. The method according to claim 17 or 18, wherein the tetravalent metal component is selected from the group consisting of zirconium, hafnium or a mixture thereof.

20. The method according to claim 17 or 18, wherein the metal-organic framework is selected from the group consisting of UiO-66, EMM-71, zirconium fumarate, MOF-808, NU-1000, or a functionalized derivative thereof.

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