Protonated covalent organic framework materials, their preparation methods and applications

Abstract

The present invention provides a method for improving the hydrogen adsorption properties of a covalent organic framework, comprising the steps of providing a covalent organic framework containing imine bonds and protonating it with hydrochloric acid vapor; the present invention further provides the protonated covalent organic framework and its use as a hydrogen storage medium.

Description

[Technical Field]

[0001] The present invention relates to the technical field of hydrogen storage materials, and in particular to the preparation and application of protonated covalent organic framework materials. [Background technology]

[0002] As humankind's energy demand and use increases, non-renewable energy sources such as fossil fuels (coal, oil, and natural gas) are becoming increasingly scarce, and the large-scale development and utilization of renewable energy has become an important component of the energy strategies of countries around the world. Hydrogen Energy Hydrogen energy is the most ideal energy source for the future, as it is abundantly available, environmentally friendly, renewable, and has high energy density. One of the biggest technical obstacles to using hydrogen energy as fuel is its storage. Hydrogen is in a gaseous state at room temperature and pressure, and its density is only 1 / 14 that of air. A car needs to consume approximately 5 to 13 kg of hydrogen to travel 482.7 km (300 miles), and 5 kg of hydrogen at room temperature and pressure can store 56 m 3 Therefore, hydrogen vehicle applications require more practical and feasible hydrogen storage methods.

[0003] Currently, various hydrogen storage methods have been proposed, with the most common being compressed gas storage and liquid hydrogen storage. While these methods are easy to implement and the technologies are mature, they each have drawbacks that are difficult to overcome. For example, storing and transporting high-pressure hydrogen gas in cylinders poses a risk because the high-pressure hydrogen can dissolve and penetrate the steel walls of the storage cylinder, potentially causing hydrogen embrittlement. This poses a significant safety risk for long-term hydrogen storage, as well as small hydrogen storage capacity and high costs. While liquid hydrogen is denser than hydrogen gas, its storage temperature is -252.8°C, which means that storage requires significant energy consumption and good insulation, resulting in high equipment requirements and high costs. Therefore, finding new hydrogen storage materials and storage and transportation methods is crucial, and porous materials have become one of the recent hot spots in materials exploration.

[0004] Adsorption is the partial retention of gas after contact with a solid. It can be divided into two categories: chemisorption and physisorption, depending on the adsorption strength, heat of adsorption, adsorption rate, selectivity, adsorption temperature, and pressure. The main chemical hydrogen storage materials are metal hydrides. Chemisorption is usually associated with an activation energy, meaning that for adsorption to be complete, molecules attracted to the surface must first pass an energy barrier and firmly bond with the surface. Therefore, most chemisorption processes have high reaction activation energies, the desorption process is slow, and some metal hydrides are irregenerate. Physisorption hydrogen storage involves accumulating gas molecules on the surface of a material without chemical reaction with the material, and adsorbing and storing the gas through molecular interactions between the gas and the material. Because the interaction between hydrogen molecules and the pore surface of the adsorbent is very weak, physisorption hydrogen storage has fast adsorption and desorption rates and is typically operated at low temperatures and high pressures. Major physical hydrogen storage materials include porous materials such as zeolites, activated carbon, carbon nanotubes, and metal-organic frameworks.

[0005] Metal-organic frameworks (MOFs) and covalent organic frameworks (COFs) are both crystalline porous materials that have been rapidly developing in recent years. MOFs are three-dimensional network crystalline structures composed of porous organic ligands, primarily aromatic acid or base nitrogen and oxygen, hybridized with inorganic metal centers through coordination bonds. Therefore, MOFs are also known as porous coordination polymers (PCPs). Their pore structure resembles that of zeolites, but their flexible frameworks mean they are also called "soft zeolites." The first generation of MOF materials was synthesized in the mid-1990s. At that time, the pore structure of MOF materials required the support of guest molecules. When the guest molecules were removed, the framework collapsed, resulting in a stable pore structure. Subsequently, researchers began assembling anionic, cationic, and neutral ligands into coordination polymers, synthesizing a new generation of MOF materials. The organic ligands in this type of MOF material are primarily carboxyl-containing organic anionic ligands, sometimes mixed with nitrogen-containing heterocyclic organic neutral ligands. This generation of MOF materials overcomes the shortcomings of previous generations by allowing the framework structure of the material to change to some extent when guest molecules are introduced or removed, or when certain external stimuli (such as pressure) are applied, but not to collapse. Covalent organic framework (COF) materials are a new type of framework material recently synthesized that can have a variety of 1D, 2D, and 3D crystalline structures. The framework of this type of material contains only organic structural units, connected by very strong covalent bonds (e.g., C—C, C—O, and B—O). Three of these materials, COF-6, COF-8, and COF-10, have a layered 2D structure similar to graphite. The other three, COF-102, COF-105, and COF-108, have a 3D structure formed by introducing triangular and tetrahedral nodes. This type of material has the advantages of large porosity and specific surface area, good thermal stability, and ease of functionalization. Compared to MOFs, COFs have a lower crystalline density, which increases the possibility of their effective use in gas storage.At the same time, the materials have greater stability and potential for further modification, since the covalent bonds connecting the COF building blocks are more stable than the coordinate bonds of MOFs.

[0006] Currently, for physical hydrogen storage materials, MOF / COF materials mainly improve the hydrogen storage properties of the material in terms of increasing its specific surface area and pore volume.

[0007] For example, MOF-5 is a representative example of many MOF compounds, and its framework [Zn4O(bdc)3] consists of Zn4O(-COO)6 units and terephthalate bdc 2- It is a three-dimensional network with a pcu topology formed by interconnecting these. Patent document WO2005003622A1 discloses a hydrogen storage container to which MOF-5 material is added, and shows that under a pressure of 3 bar, the hydrogen storage weight of the container to which MOF-5 is added increases by 1.46 times compared to a container to which MOF-5 is not added.

[0008] Physical hydrogen storage materials have a trade-off between large specific surface area and material stability. MOF / COF materials with large specific surface area are always produced by highly reversible reactions (e.g., boric acid in COF, 3D boric acid COF, its BET reaches ~5000), which means they have a high tendency to decompose (low chemical stability). In addition, pore collapse is also an unavoidable problem for MOF / COF materials with large specific surface area. For example, a MOF / COF with a BET specific surface area of ​​5000 m 2 MOFs with a specific surface area exceeding 7200 m / g always require a complex activation process, requiring methods such as supercritical CO2. This shows that if the specific surface area is too large, problems arise in both chemical stability and the collapse of the pore structure. 2Even with MOF materials with a specific surface area of ​​0.1 / g, the hydrogen storage density requirements proposed by the US Department of Energy for hydrogen storage systems cannot be met, so finding solutions other than increasing the BET specific surface area has become a worthwhile research direction for MOF / COF-type physical hydrogen storage materials. Further tuning the heat of adsorption based on COF materials with a high specific surface area product is a very good starting point, but systematic investigation is still needed into how to achieve heat of adsorption control at the material level.

[0009] Combining the properties of physical and chemical hydrogen storage materials is key to developing effective hydrogen storage materials and a major challenge in the field of hydrogen storage. To achieve the desired hydrogen storage properties for hydrogen storage and transportation, the current scientific field needs to combine the high heat of adsorption of chemical hydrogen storage materials with the low heat of adsorption of porous physical hydrogen storage materials, i.e., to adjust the pore environment of the porous material to enhance interaction with hydrogen molecules. Summary of the Invention [Problem to be solved by the invention]

[0010] To solve the above-mentioned technical problems, the present inventors discovered that protonating a covalent organic framework (COF) compound can significantly increase the heat of hydrogen adsorption and the hydrogen storage capacity. By selecting a highly stable imine-bonded COF and protonating the imine bond through treatment with hydrochloric acid vapor, the hydrogen storage capacity of the COF can be enhanced. [Means for solving the problem]

[0011] A first aspect of the present invention provides a protonated covalent organic framework, the covalent organic framework having a structure represented by formula (I): TIFF2025539033000001.tif124170

[0012] wherein R1 and R2 are each independently selected from H, a C1-C6 alkyl group, a methoxy group, and an ethoxy group; A is a 6-membered aromatic ring or a heteroaromatic ring; J is a protonatable site, and One or more J's are protonated.

[0013] A second aspect of the present invention provides a method for improving the hydrogen adsorption properties of a covalent organic framework comprising imine bonds, the method comprising the step of protonating the covalent organic framework with hydrochloric acid vapor.

[0014] Another aspect of the present invention includes the use of the protonated covalent organic framework material described above, or the covalent organic framework material obtained by the above method, as a hydrogen storage medium. [Effects of the Invention]

[0015] The beneficial effects of the present invention are as follows:

[0016] 1. In the prior art, modification treatments of hydrogen storage materials usually involve increasing the specific surface area of ​​the material or doping the material to improve the material's hydrogen storage properties, which requires complicated operations and high costs. In comparison, the present invention improves the hydrogen adsorption properties of imine-type covalent organic frameworks through a simple protonation treatment, which is advantageous in solving the problem of low hydrogen storage capacity of existing hydrogen storage materials.

[0017] 2. The low heat of adsorption of covalent organic framework compounds in the prior art hinders their widespread use and application as hydrogen storage media. The present invention proposes a simple protonation treatment method to increase the heat of adsorption of porous physical hydrogen storage materials, thereby improving the hydrogen storage capacity of the materials, which is beneficial to promoting the practical application and development of covalent organic frameworks in the field of hydrogen storage.

[0018] 3. The method of the present invention is versatile and works well for covalent organic frameworks of different structures.

[0019] 4. In the prior art, all methods for modifying hydrogen storage materials are limited to milligram-level laboratory scale. In comparison, the method of the present invention can be scaled up for production, which is advantageous for industrial application. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 1 is a schematic diagram of a process for preparing a protonated covalent organic framework according to the present invention. [Figure 2] X-ray diffraction (XRD) patterns of the covalent organic framework material before and after protonation treatment. [Figure 3] 1 shows infrared spectra of covalent organic framework materials before and after protonation. [Figure 4] Hydrogen adsorption-desorption isotherms of covalent organic framework materials before and after protonation treatment. [Figure 5] 1 is a graph showing the relationship between the amount of hydrogen adsorption and pressure (bar) of a covalent organic framework material before and after protonation. DETAILED DESCRIPTION OF THE INVENTION

[0021] As used herein, the terms covalent organic framework, covalent organic framework, and COF can be used interchangeably.

[0022] The terms "protonation" and "acidification" can be used interchangeably and refer to the attachment of a proton (or positively charged hydrogen ion) to a protonatable site on a compound.

[0023] The term "protonatable site" refers to an electron-donating group in a compound that can be protonated by bonding with a proton in an acid.

[0024] Additionally, unless otherwise defined, all terms used herein should be understood to have the same meaning as commonly understood by one of ordinary skill in the art.

[0025] In order to make the technical solutions and advantages of the present invention clearer and easier to understand, the present invention will be clearly and completely described below through specific embodiments in conjunction with the drawings, and it should be noted that, provided that they are not mutually contradictory, each embodiment or each technical feature described below can be arbitrarily combined to form a new embodiment.

[0026] It should also be noted that terms such as "exemplary" or "for example" are used herein to indicate an example, instance, or illustration. An embodiment or design described as "exemplary" or "for example" herein is not to be construed as preferred or more advantageous over other embodiments or designs. Rather, the use of terms such as "exemplary" or "for example" is intended to concretely illustrate the relevant concept.

[0027] In the present invention, "at least one" means one or more, and "multiple" means two or more. "And / or" describes a relationship between related objects and indicates that a three-way relationship may exist. For example, A and / or B can represent the singular presence of A, the simultaneous presence of A and B, or the singular presence of B, where A and B may be singular or plural. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or multiple items. For example, "at least one of a, b, or c" can represent a, b, c, a and b, a and c, b and c, or a, b, and c, where a, b, and c are singular or plural. It should be noted that "at least one" can be interpreted as "one or multiple items."

[0028] As described above, the present invention provides a protonated covalent organic framework, the covalent organic framework having a structure represented by formula (I), wherein J is a protonatable moiety. The protonatable moiety refers to any group that can be protonated. Preferably, J is an imine bond, and the C atom of each imine bond is connected to a benzene ring containing R1 and R2 in formula (I).

[0029] According to the protonated covalent organic framework of the present invention, the protonation is achieved by contacting the covalent organic framework with hydrochloric acid vapor, which refers to hydrogen chloride gas that is substantially free of water molecules or free of water molecules, obtained after volatilizing concentrated hydrochloric acid.

[0030] In this specification, "substantially free of water molecules" means that the proportion of gaseous water molecules in the mixture of hydrogen chloride gas and gaseous water molecules is less than 7% by volume, preferably less than 3% by volume, and more preferably less than 1% by volume.

[0031] According to the protonated covalent organic framework of the present invention, A in the structure represented by formula (I) is a benzene ring or an S-triazine ring.

[0032] According to the protonated covalent organic framework material of the present invention, R1 and R2 in the structure represented by formula (I) may each independently be selected from -H, an alkyl group, a hydroxyalkyl group, and an alkoxy group; preferably, R1 and R2 may each independently be selected from -H, a C1-C6 alkyl group, a C1-C6 hydroxyalkyl group, and a C1-C6 alkoxy group; more preferably, R1 and R2 may each independently be selected from -H, a methyl group, an ethyl group, an isopropyl group, an isobutyl group, a tert-butyl group, a methoxy group, an ethoxy group, a hydroxyisopropyl group, and a hydroxyethyl group; and most preferably, R1 and R2 are methoxy groups.

[0033] The present invention further provides a method for improving the hydrogen adsorption properties of a covalent organic framework comprising an imine bond, the method comprising protonating the covalent organic framework with hydrochloric acid vapor.

[0034] The protonation treatment can be achieved by placing the covalent organic framework in hydrochloric acid vapor or by introducing hydrochloric acid vapor into the covalent organic framework, as long as the covalent organic framework and hydrochloric acid vapor are in contact for an appropriate period of time. For example, concentrated hydrochloric acid of a predetermined concentration can be placed in a dryer filled with discoloring silicone balls at room temperature and pressure, and the vaporized hydrogen chloride gas can be brought into contact with the covalent organic framework. For example, the concentration of the concentrated hydrochloric acid is greater than 20 wt%, preferably greater than 36 to 38 wt%, and more preferably greater than 37 wt%.

[0035] In the method of the present invention, the hydrochloric acid vapor refers to hydrogen chloride gas that is substantially free of water molecules or that is free of water molecules and obtained after volatilizing concentrated hydrochloric acid. In a preferred embodiment of the present invention, the water molecules in the hydrogen chloride gas obtained after volatilizing concentrated hydrochloric acid are substantially adsorbed by a desiccant, so that the hydrochloric acid vapor is hydrogen chloride gas that is substantially free of water molecules. The desiccant may be a common desiccant in the art that does not react with hydrogen chloride gas. For example, the desiccant may be selected from calcium chloride, silica gel, silicon tetrachloride, phosphorus pentoxide, or concentrated sulfuric acid. After extensive research, the present inventors unexpectedly discovered that the protonated covalent organic framework material of the present invention obtained by protonation with hydrochloric acid vapor has a larger pore volume, a larger specific surface area, and better gas adsorption properties. When COF is treated with an aqueous hydrochloric acid solution, the reaction process is too violent. On the one hand, the presence of a large amount of hydrogen chloride molecules and water molecules in the pores of the COF causes a rapid decrease in the pore volume and specific surface area of ​​the material, resulting in a significant deterioration in gas adsorption properties. On the other hand, water molecules are adsorbed in the pores of the COF and are difficult to remove. If the COF is dried, the water molecules and hydrogen chloride molecules are removed together, resulting in the loss of the protonation effect. Therefore, within the scope of the present invention, it is advantageous to perform the protonation treatment using hydrochloric acid vapor containing a small amount of water molecules or substantially no water molecules.

[0036] In the method of the present invention, the protonation time is preferably 30 to 180 minutes, more preferably 45 to 120 minutes, such as 35, 40, 45, 50, 52, 54, 56, 58, 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 85, 90, 95, 100, 105, 110, 115, 120, 130, 140, 150, 160, or 170 minutes. Those skilled in the art can adjust the protonation time within the above range depending on the COF material used, thereby avoiding insufficient protonation due to a treatment time that is too short, or damage to the structure of the COF material due to a treatment time that is too long.

[0037] According to the method of the present invention, the covalent organic framework material containing imine bonds is produced by reacting a polyamino monomer and a polyaldehyde monomer in a mixed solvent and catalyzing the reaction with a catalyst. Typically, the reaction is carried out at 100 to 150°C, preferably 100 to 130°C, more preferably 110, 112, 114, 116, 118, or 120°C, and most preferably 120°C.

[0038] According to the method of the present invention, the polyamino monomer is a compound containing two or more amino groups, for example, the polyamino monomer can be selected from ethylenediamine, diethylenetriamine, triethylenetetramine, tetraethylenepentamine, pentaethylenehexamine and other polyenepolyamines, p-phenylenediamine, triaminobenzene and other polyamino aromatic compounds, diaminoheterocyclic compounds, triaminoheterocyclic compounds or polyaminoheterocyclic compounds. Preferably, the polyamino compound is 1,3,5-tris(4-aminophenyl)benzene.

[0039] According to the method of the present invention, the polyaldehyde monomer is a compound containing two or more aldehyde groups. For example, the polyaldehyde monomer is selected from substituted or unsubstituted terephthalaldehyde, substituted or unsubstituted biphenyldicarboxaldehyde, and substituted or unsubstituted p-thiophenedicarboxaldehyde. Preferably, the polyaldehyde monomer is a substituted terephthalaldehyde. More preferably, the polyaldehyde monomer is 2,5-dimethoxyterephthalaldehyde.

[0040] According to the method of the present invention, the catalyst can be selected from any catalyst known in the art, for example, the catalyst can be selected from one or more of formic acid, acetic acid, p-toluenesulfonic acid, oxalic acid, lactic acid, hydrochloric acid, sulfuric acid, and pyrrolidine, preferably, the catalyst is selected from acetic acid.

[0041] According to the method of the present invention, the mixed solvent can be selected from any mixed solvent known in the art. For example, the mixed solvent may be any of ethylene glycol + cyclohexane, mesitylene + dioxane, n-butanol + dioxane, o-dichlorobenzene + n-butanol, and mesitylene + n-butanol. In the mixed solvent, the volume ratio of the former to the latter is 9:1 to 1:9, for example, 5:1 to 1:5, 3:1 to 1:3, and preferably the volume ratio of the two liquids is 1:1.

[0042] Preferred conditions of the present invention will be further described below with reference to the drawings in conjunction with examples. It should be understood that the preferred examples described herein are merely for the purpose of explaining and interpreting the present invention, and are not intended to limit the present invention.

[0043] All raw materials or reagents used in the following examples are commercially available or self-made.

[0044] Example 1 (Preparation of imine-type covalent organic frameworks) 1,3,5-Tris(4-aminophenyl)benzene (TPB) (0.1 mmol) and 2,5-dimethoxyterephthalaldehyde (DMTP) (0.15 mmol) were added to a 1 mL o-dichlorobenzene (o-DCB) + n-butanol (BuOH) mixed solvent (1:1 volume ratio) and dissolved in the mixed solvent to obtain a mixture. Acetic acid (6 mol / L, 0.1 mL) was added to the mixture, which was then heated to 120 °C and incubated for 3 days. The reaction product was filtered, washed, and purified to obtain an imine-type covalent organic framework named DMTP-TPB-COF. See Figure 1.

[0045] (Preparation of Protonated Imine-Type Covalent Organic Frameworks) A protonated imine-type covalent organic framework was prepared by treating it with hydrochloric acid vapor. A 37 wt% hydrochloric acid solution was placed in a dryer filled with discoloring silicone balls at room temperature and atmospheric pressure. The resulting DMTP-TPB-COF was then left in the dryer for 60 minutes to obtain a protonated COF designated H@DMTP-TPB-COF. See Figure 1.

[0046] Effectiveness measurement (crystal structure analysis and chemical composition measurement) The crystalline structure of the materials was analyzed using powder crystal X-ray diffraction (XRD), and the chemical composition of the materials was analyzed by infrared. As shown in Figure 2, the powder crystal XRD results for DMTP-TPB-COF and H@DMTP-TPB-COF confirmed that the protonation treatment did not significantly affect the crystalline structure of the COF materials. Figure 3 shows that the imine bonds were successfully protonated after the protonation treatment.

[0047] (BET specific surface area measurement and hydrogen storage capacity measurement) Using a gas adsorption apparatus, the obtained covalent organic framework compound was subjected to BET specific surface area measurement and hydrogen storage capacity measurement.

[0048] The atmospheric pressure gas adsorption apparatus used was a BELSORP-max II manufactured by MicrotracBEL.

[0049] The high-pressure hydrogen adsorption apparatus used was a Micromerics Instrument Corporation HPVA-100 high-pressure volumetric analyzer.

[0050] The BET specific surface area was determined from the N2 adsorption isotherm at 77 K, and the surface area of ​​the material was calculated using the BET (Brunauer-Emmett-Teller) equation.

[0051] The hydrogen storage capacity at 77K under atmospheric pressure was measured by using an atmospheric pressure gas adsorption analyzer and determining the hydrogen adsorption isotherm by the dynamic volumetric method.

[0052] The hydrogen storage capacity at 77K and high pressure was measured by using a high-pressure gas adsorption analyzer to obtain the high-pressure adsorption isotherm of hydrogen by the static volumetric method.

[0053] The measured BET specific surface area, hydrogen storage capacity at 77 K under normal pressure, and hydrogen storage capacity at 77 K under high pressure (80 bar) are shown in Table 1.

[0054] TIFF2025539033000002.tif87170

[0055] The inventors discovered that after protonation, the specific surface area of ​​the COF decreased to some extent due to the introduction of protons. However, surprisingly, the protonation of the imine bonds increased the heat of adsorption of the imine moiety, significantly increasing the hydrogen storage capacity of the COF. Referring to the ambient pressure hydrogen adsorption-desorption isotherms in Figure 4 and the hydrogen adsorption-pressure curves in Figure 5, the hydrogen adsorption capacity of H@DMTP-TPB-COF was found to be much higher than that of DMTP-TPB-COF under both ambient and high pressure conditions. This demonstrates that protonation improves the hydrogen adsorption properties of covalent organic frameworks, which is a simple, versatile, and effective strategy for improving the hydrogen storage properties of covalent organic frameworks.

Claims

1. A protonated covalent organic framework, the covalent organic framework having a structure shown in formula (I): However, R １ and R ２ are each independently —H, C １ ~C ６ Alkyl group, C １ ~C ６ Hydroxyalkyl groups, and C １ ~C ６ alkoxy groups, A is a 6-membered aromatic ring or a heteroaromatic ring; J is a protonatable site, and a protonated covalent organic framework, wherein one or more J are protonated;

2. J is an imine bond, and the C atom of each of said imine bonds is R １ and R ２ 10. The protonated covalent organic framework of claim 1, wherein the protonated covalent organic framework is connected to a benzene ring containing

3. 3. The protonated covalent organic framework of claim 1, wherein A is a benzene ring or an S-triazine ring.

4. R １ and R ２ are each independently selected from —H, methyl, ethyl, isopropyl, isobutyl, tert-butyl, methoxy, ethoxy, hydroxyisopropyl, and hydroxyethyl groups.

5. 1. A method for enhancing the hydrogen adsorption properties of a covalent organic framework material, the method comprising the step of protonating a covalent organic framework material comprising imine bonds with hydrochloric acid vapor.

6. The covalent organic framework material containing imine bonds has a structure represented by formula (I): However, R １ and R ２ are each independently H, C １ ~C ６ selected from alkyl groups, methoxy groups, and ethoxy groups; A is a 6-membered aromatic ring or a heteroaromatic ring; J is an imine bond, and the C atom of each of said imine bonds is R １ and R ２ 6. The method of claim 5, wherein the alkyl group is connected to a benzene ring containing

7. The method of claim 6, wherein A is a benzene ring or an S-triazine ring.

8. R １ and R ２ The method of claim 6 , wherein is a methoxy group.

9. The method according to claim 5 or 6, wherein the protonation treatment time is 30 to 180 minutes.

10. 7. The method according to claim 5 or 6, wherein the covalent organic framework material containing imine bonds is prepared by reacting polyamino monomers and polyaldehyde monomers as reactants in a mixed solvent and catalyzing the reaction with a catalyst.

11. The method of claim 10, wherein the reaction is carried out at 100°C to 150°C.

12. 7. The method according to claim 5 or 6, wherein the hydrochloric acid vapor is obtained by volatilizing concentrated hydrochloric acid.

13. 7. The method according to claim 5 or 6, wherein the hydrochloric acid vapor is hydrogen chloride gas that is substantially free of water molecules or free of water molecules, obtained by volatilizing concentrated hydrochloric acid and then drying it with a desiccant.

14. Use of a protonated covalent organic framework according to any one of claims 1 to 4 or a covalent organic framework obtainable by the method according to any one of claims 5 to 13 as a hydrogen storage medium.

Images