Zirconium-based metal-organic framework for use as a heavy metal adsorbent in condensate and method for preparing same

Abstract

The present invention relates to a method for producing a tetravalent zirconium ion (Zr 4+ ) and the tetravalent zirconium ion (Zr 4+ The present invention also relates to a method for preparing a zirconium-based metal-organic framework comprising the steps of: (a) preparing a reaction mixture in a solvent comprising a zirconium compound, a linking ligand, and optionally a modifier; (b) heating the reaction mixture obtained in step (a); and (c) washing the reaction product obtained in step (b) with a solvent and drying the reaction product. The zirconium-based metal-organic framework according to the present invention is suitable for use in a process for removing heavy metals in a condensate, in particular for the adsorption, removal, or reduction of arsenic and mercury content in the condensate.

Description

[Technical Field]

[0001] Chemistry relating to zirconium-based metal-organic frameworks for use as adsorbents for heavy metals in condensates and methods for their preparation. [Background technology]

[0002] In the petroleum exploration and production industry, petroleum products, such as crude oil, natural gas, and natural gas liquids (NGLs) (also known as condensate or natural gas condensate), which are natural hydrocarbon compounds obtained from the production process, generally contain heavy metal contaminants such as arsenic (As) and mercury (Hg). These heavy metal contaminants cause disadvantages in terms of toxicity and corrosiveness, and are problematic for subsequent processes that use petroleum products, especially condensate, as starting materials, for example in the petrochemical industry. Arsenic and mercury contained in condensate are in the form of various compounds, such as mercury sulfide (HgS), mercury oxide (HgO), and arsenopyrite (AsFeS).

[0003] Therefore, to meet the need to reduce or remove heavy metal contaminants, particularly arsenic and mercury compounds contained in condensates, attempts have been made to develop methods and materials for use in adsorbing these contaminants.

[0004] Metal-organic frameworks, which have structures consisting of metal clusters and organic linking ligands, are considered as novel porous materials of great interest and have been applied in various applications such as gas storage, gas separation, chemical sensors, heterogeneous catalysis, etc. Industrially, metal-organic frameworks are another interesting option for use as adsorbents with required adsorption properties depending on the structure and porosity, which can be tuned depending on the type of selected metal cluster and linking ligand.

[0005] An example of an invention relating to the development of metal organic frameworks for use as pollutant adsorbents is provided below.

[0006] WO 2020 / 130953 discloses a copper-based metal-organic framework for use in removing carbon dioxide (CO) and other contaminants such as mercury, arsenic, and hydrogen sulfide (HS) from petroleum. The copper-based metal-organic framework is obtained by a process comprising mixing a copper(II) (Cu(II)) salt with 2,5-dibromobenzene-1,4-dicarboxylic acid, dimethylformamide (DMF), and methanol, heating the mixture, and recovering the product.

[0007] WO 2020 / 130954 discloses a copper-based metal-organic framework for use in removing carbon dioxide (CO) and other contaminants such as Hg, As, and hydrogen sulfide (HS) from petroleum. The copper-based metal-organic framework is obtained by a process comprising mixing together a copper(II) (Cu(II)) salt, 1,2,4,5-tetrabromobenzenedicarboxylic acid, methanol, and water, heating the mixture, and recovering the product.

[0008] US Pat. No. 10,260,148 discloses a porous material comprising a metal-organic framework and a porous organic polymer for purifying electronic gases and removing mercury from hydrocarbon streams. Summary of the Invention

[0009] The first aspect of the present invention is a method for producing a tetravalent zirconium ion (Zr 4+ ) and the tetravalent zirconium ion (Zr 4+ and a bidentate or tridentate linking ligand binding a zirconium-based metal organic framework (Zr-based metal organic framework) for use as a heavy metal adsorbent in condensate, wherein the zirconium-based metal organic framework of the present invention may be subjected to a surface treatment with a solution of an alkali metal hydroxide to improve or enhance the adsorption efficiency of heavy metals in the condensate.

[0010] A second aspect of the present invention is (a) preparing a reaction mixture in a solvent comprising a zirconium compound, a linking ligand, and optionally a modifier; (b) heating the reaction mixture obtained in step (a) at a temperature in the range of 80 to 150°C for 6 to 48 hours; (c) washing the reaction product obtained in step (b) with a solvent and drying the reaction product at a temperature in the range of 80 to 150°C for 6 to 15 hours; The present invention relates to a method for preparing a zirconium-based metal-organic framework for use as a heavy metal adsorbent in condensate, comprising:

[0011] Optionally, the method for preparing the zirconium-based metal-organic framework according to the present invention may further comprise a step (d) of contacting the reaction product obtained in the step (c) with an aqueous alkali metal hydroxide solution at ambient temperature for 12 to 36 hours.

[0012] A third aspect of the present invention relates to a method for removing heavy metals from a condensate, comprising contacting the condensate with an adsorbent comprising the zirconium-based metal-organic framework according to the present invention.

[0013] An object of the present invention is to provide a zirconium-based metal-organic framework capable of adsorbing, removing, or reducing contaminants that are heavy metal compounds, particularly arsenic (As) and mercury (Hg) that may be present in condensate as compounds containing these heavy metals.

[0014] It is a further object of the present invention to provide a method for preparing zirconium-based metal-organic frameworks that allows optimizing the properties of the frameworks for use as adsorbents for the aforementioned contaminants in condensates.

[0015] Another object of the present invention is to provide a method for removing the above-mentioned contaminants from condensate using an adsorbent that is the zirconium-based metal-organic framework of the present invention or an adsorbent that includes the zirconium-based metal-organic framework of the present invention.

[0016] The zirconium-based metal-organic frameworks prepared and characterized according to the present invention have demonstrated excellent efficiency in adsorbing heavy metal compounds, particularly arsenic and mercury, in condensate. They can remove up to about 85% of the arsenic compounds in the condensate and up to about 99% of the mercury compounds in the condensate. Furthermore, the zirconium-based metal-organic frameworks according to the present invention have been found to have significantly higher removal rates (%) of arsenic and mercury compounds in condensate than other types of commonly available metal-organic frameworks. [Brief explanation of the drawings]

[0017] [Figure 1] 1(a) shows powder X-ray diffraction patterns of Example 1 (FIG. 1(a)), Example 2 (FIG. 1(b)), and Example 3 (FIG. 1(c)), which are examples of the zirconium-based metal-organic framework according to the present invention. [Figure 2] FIG. 1(a) shows nitrogen adsorption and desorption isotherms for Example 1 (FIG. 1(a)), Example 2 (FIG. 1(b)), and Example 3 (FIG. 1(c)), which are examples of the zirconium-based metal-organic framework according to the present invention. [Figure 3] 1 shows nitrogen adsorption / desorption isotherms for Example 1, which is an example of the zirconium-based metal-organic framework according to the present invention, and Comparative Examples A and B. DETAILED DESCRIPTION OF THE INVENTION

[0018] Any embodiment shown herein is intended to encompass applications to other embodiments of the invention as well, unless otherwise indicated. Unless otherwise specified, technical and scientific terms used herein have the meanings understood by one of ordinary skill in the art. Throughout this invention, the term "about" is used to indicate that any value appearing or indicated herein may have a variation or deviation. Such variation or deviation may be due to instrument error or the method used to determine the value. The words "consist(s) of," "comprise(s)," "contain(s)," and "include(s)" are open-ended verbs. For example, a method that "consist(s) of," "comprise(s)," "contain(s)," or "include(s)" an element or elements, or a step or steps, is not limited to only the element or step, or the step or steps, but also includes unspecified elements or steps. Any tools, apparatus, methods, materials, or chemicals referred to herein mean tools, apparatus, methods, materials, or chemicals commonly used or practiced by those skilled in the art, unless otherwise specified. All components and / or methods disclosed and claimed in the present invention are intended to encompass aspects of the present invention resulting from the act, practice, modification, or alteration of any element, even if not specifically recited in the claims, that confer the characteristics and utility of the aspects of the present invention and provide the same effects according to the judgment of one skilled in the art without requiring substantially different experimentation from the present invention. Accordingly, substitutions or similarities of the aspects of the present invention, and slight modifications or variations that are obvious to those skilled in the art, are also deemed to be within the spirit, scope, and concept of the present invention. The term "condensate" in the present invention is intended to encompass "condensate oil," "natural gas liquids (NGL)," or "natural gas condensate," as commonly used in the art. As an example, the term "condensate" encompasses a mixture of liquid hydrocarbons having a molecular weight ranging from 1 to 14 carbon atoms, preferably 3 to 14 carbon atoms. Aspects of the present invention are described in more detail below.

[0019] Zirconium-based metal-organic frameworks The first aspect of the present invention is a method for producing a tetravalent zirconium ion (Zr 4+ ) and the tetravalent zirconium ion (Zr 4+and a bidentate or tridentate linking ligand that binds a zirconium-based metal-organic framework (MOR) to a heavy metal sorbent.

[0020] In an alternative embodiment, the zirconium-based metal-organic framework is subjected to a surface treatment with an alkali metal hydroxide solution, in particular, a surface treatment with an alkali metal hydroxide solution whose pH is controlled in the range of 7 to 12, preferably 7 to 8.

[0021] By way of example, such a surface treatment with an alkali metal hydroxide solution may be carried out at ambient temperature for 12 to 36 hours.

[0022] Alkali metal hydroxides suitable for surface treatment according to the present invention may be selected from the group consisting of sodium hydroxide, potassium hydroxide, and mixtures thereof.

[0023] Preferably, such alkali metal hydroxide solution is aqueous sodium hydroxide.

[0024] The linking ligand may be selected from the group consisting of 1,4-benzenedicarboxylic acid, 1,3,5-benzenetricarboxylic acid, but-2-enedioic acid, and mixtures thereof.

[0025] In more specific embodiments, tetravalent zirconium ions (Zr 4+ ) is derived from either zirconium tetrachloride, zirconium oxychloride, zirconium oxychloride octahydrate, zirconium dioxide, zirconium tetrahydroxide, or mixtures thereof.

[0026] Preferably, tetravalent zirconium ions (Zr 4+ ) is derived from zirconium tetrachloride or zirconium oxychloride octahydrate.

[0027] The zirconium-based metal-organic framework of the present invention comprises a cluster node of six zirconium atoms (Zr6 cluster node) and eight oxygen atoms partially linked to linking ligands.

[0028] Preferably, the zirconium-based metal organic framework contains tetravalent zirconium ions (Zr 4+ ) to the linking ligand is in the range of 1:1 to 3.

[0029] Furthermore, the zirconium-based metal organic framework has a molecular weight of 300 to 1000 m. 2 / g.

[0030] Preferably, the zirconium-based metal organic framework according to the present invention has a thickness of 0.2 to 1.2 cm 3 / g and has an average pore diameter in the range of 3 to 5 nm.

[0031] Preferably, the zirconium-based metal-organic framework has a type I or type IV nitrogen adsorption-desorption isotherm.

[0032] The zirconium-based metal-organic framework of the present invention is particularly suitable for use as a sorbent for arsenic and / or mercury in condensates.

[0033] Furthermore, the present invention also relates to an adsorbent comprising the zirconium-based metal-organic framework having the above-described characteristics according to the present invention.

[0034] A second aspect of the present invention relates to a method for preparing a zirconium-based metal-organic framework for use as a heavy metal adsorbent in condensate.

[0035] The method for preparing a zirconium-based metal-organic framework for use as a heavy metal adsorbent in condensate according to the present invention comprises the steps of: (a) preparing a reaction mixture in a solvent comprising a zirconium compound, a linking ligand, and optionally a modifier; (b) heating the reaction mixture obtained in step (a) at a temperature in the range of 80 to 150°C for 6 to 48 hours; (c) washing the reaction product obtained in step (b) with a solvent and drying the reaction product at a temperature in the range of 80 to 150°C for 6 to 15 hours; Includes:

[0036] The method for producing the zirconium-based metal organic framework according to the present invention may further comprise a step (d) of contacting the reaction product obtained in the step (c) with an aqueous alkali metal hydroxide solution at ambient temperature for 12 to 36 hours.

[0037] Preferably, in step (d), the pH of the aqueous alkali metal hydroxide solution is controlled in the range of 7-12, preferably 7-8.

[0038] Such alkali metal hydroxides used in step (d) may be selected from the group consisting of sodium hydroxide, potassium hydroxide, and mixtures thereof.

[0039] Preferably, the aqueous alkali metal hydroxide solution according to the method of the present invention is aqueous sodium hydroxide solution.

[0040] In a further embodiment, the method for preparing a zirconium-based metal-organic framework further comprises step (e) of washing the product obtained in step (d) with a solvent and drying the product at a temperature in the range of 80 to 150°C for 6 to 12 hours.

[0041] Preferably, in step (e), the solvent is water.

[0042] In certain embodiments, the molar ratio of zirconium compound to linking ligand in step (a) ranges from 1:1-3.

[0043] Alternatively, the molar ratio of the zirconium compound to the modifier in step (a) is in the range of 1:4-6.

[0044] Optionally, the molar ratio of zirconium compound to modifier in step (a) is in the range of 1:300-400.

[0045] In a particular embodiment of the present invention, the method for preparing a zirconium-based metal-organic framework comprises: (a) preparing a reaction mixture comprising a zirconium compound and a linking ligand in a solvent; (b) heating the reaction mixture obtained in step (a) at a temperature in the range of 100 to 150°C for 12 to 36 hours; (c) washing the reaction product obtained in step (b) with a solvent and drying the reaction product at a temperature in the range of 100 to 150°C for 6 to 15 hours; (d) contacting the reaction product obtained in step (c) with an aqueous alkali metal hydroxide solution having a pH controlled in the range of 7 to 12 at ambient temperature for 12 to 36 hours; (e) washing the product obtained in step (d) with a solvent and drying the product at a temperature in the range of 80 to 150°C for 6 to 12 hours; In step (a), the molar ratio of the zirconium compound to the linking ligand is in the range of 1:1-3.

[0046] In a more specific embodiment of the present invention, the method for preparing a zirconium-based metal-organic framework comprises: (a) preparing a reaction mixture in a solvent comprising a zirconium compound, a linking ligand, and a modifier; (b) heating the reaction mixture obtained in step (a) at a temperature in the range of 80 to 150°C for 24 to 48 hours; (c) washing the reaction product obtained in step (b) with a solvent and drying the reaction product at a temperature in the range of 100 to 150°C for 6 to 12 hours; (d) contacting the reaction product obtained in step (c) with an aqueous alkali metal hydroxide solution having a pH controlled in the range of 7 to 12 at ambient temperature for 12 to 36 hours; (e) washing the product obtained in step (d) with a solvent and drying the product at a temperature in the range of 80 to 150°C for 6 to 12 hours; In step (a), the molar ratio of the zirconium compound to the linking ligand is in the range of 1:1 to 3; In step (a), the molar ratio of the zirconium compound to the modifier is in the range of 1:300-400.

[0047] In another particular embodiment of the present invention, the method for preparing a zirconium-based metal-organic framework comprises the steps of: (a) preparing a reaction mixture in a solvent comprising a zirconium compound, a linking ligand, and a modifier; (b) heating the reaction mixture obtained in step (a) at a temperature in the range of 90 to 110°C for 4 to 8 hours; (c) washing the reaction product obtained in step (b) with a solvent and drying the reaction product at a temperature in the range of 80 to 150°C for 6 to 12 hours; In step (a), the molar ratio of the zirconium compound to the linking ligand is in the range of 1:1 to 3; In step (a), the molar ratio of the zirconium compound to the modifier is in the range of 1:4-6.

[0048] Preferred zirconium compounds according to the method of the present invention may be selected from the group consisting of zirconium tetrachloride, zirconium oxychloride, zirconium oxychloride octahydrate, zirconium dioxide, zirconium tetrahydroxide, and mixtures thereof.

[0049] More preferably, the zirconium compound is zirconium oxychloride octahydrate or zirconium tetrachloride.

[0050] Preferred linking ligands according to the method of the present invention may be selected from the group consisting of 1,4-benzenedicarboxylic acid, 1,3,5-benzenetricarboxylic acid, but-2-enedioic acid, and mixtures thereof.

[0051] Preferred modifiers according to the method of the present invention may be selected from the group consisting of formic acid, acetic acid, propionic acid, and mixtures thereof.

[0052] Even more preferably, the modifier is formic acid or acetic acid.

[0053] According to the method of the present invention, the solvent that can be used in steps (a) and (c) can be water and / or an organic solvent, for example, acetone, dimethylformamide (DMF), dimethyl sulfoxide (DMSO), alcohols such as methanol, ethanol, etc.

[0054] Specifically, in step (a), the solvent may be selected from the group consisting of dimethylformamide, water, dimethyl sulfoxide, methanol, ethanol, and mixtures thereof.

[0055] Preferably, in step (a), the solvent is dimethylformamide or water.

[0056] Specifically, in step (c), the solvent may be selected from the group consisting of dimethylformamide, acetone, methanol, ethanol, water, and mixtures thereof.

[0057] A third aspect of the present invention relates to a method for removing heavy metals from a condensate, comprising contacting the condensate with an adsorbent comprising a zirconium-based metal-organic framework characterized according to the present invention or prepared according to the methods of the present invention.

[0058] In certain embodiments, the heavy metal removal process of the present invention comprises contacting the condensate with an adsorbent at a temperature in the range of 18-80° C. and a pressure in the range of 1-30 bar. [Example]

[0059] The present invention will now be described in more detail with reference to the following experimental examples and accompanying drawings, which should not be construed as limiting the scope of the present invention.

[0060] 1. Preparation of Zirconium-Based Metal-Organic Framework Examples The following chemicals, methods, and conditions are used to prepare exemplary zirconium-based metal-organic frameworks (Examples 1-3) according to the present invention.

[0061] Example 1 ZrOCl2·8H2O and 1,4-benzenedicarboxylic acid (the molar ratio of ZrOCl2·8H2O to 1,4-benzenedicarboxylic acid was approximately 1:1) were dissolved in DMF. The resulting mixture (i.e., reaction mixture) was sonicated for 1 minute. The mixture was then heated in an oven at 120 °C for 24 hours to allow the reaction to proceed. Upon completion, the resulting solid product was collected by centrifugation. The product was washed with DMF (three times) and acetone (three times) and then dried under vacuum at 150 °C for 12 hours. The surface of the dried product was then treated by stirring in an aqueous NaOH solution for 24 hours. Upon completion, the product was washed with deionized water (DI water) (three times) and dried under vacuum at 150 °C for 12 hours to obtain the final product as a white solid.

[0062] <Example 2> ZrOCl2·8H2O and but-2-enedioic acid (the molar ratio of ZrOCl2·8H2O to but-2-enedioic acid was approximately 1:1) were dissolved in a mixture of water and formic acid (the molar ratio of ZrOCl2·8H2O to formic acid was approximately 1:6). The resulting mixture (i.e., reaction mixture) was sonicated for 5 minutes. The mixture was then heated in an oven at 100 °C for 6 hours to allow the reaction to proceed. Upon completion, the resulting solid product was collected by centrifugation. The product was washed with deionized water (three times) and ethanol (three times) and then dried under vacuum at 150 °C for 12 hours to obtain the final product as a white solid.

[0063] Example 3 ZrCl4 and 1,3,5-benzenetricarboxylic acid (ZrCl4 to 1,3,5-benzenetricarboxylic acid molar ratio: approximately 1:3) were dissolved in a mixture of DMF and formic acid (ZrCl4 to formic acid molar ratio: approximately 1:358). The mixture was sonicated for 20 minutes. The mixture was then heated in an oven at 130 °C for 48 hours to allow the reaction to proceed. Upon completion, the resulting solid product was collected by centrifugation. The product was washed with DMF (three times) and ethanol (three times) and then dried under vacuum at 150 °C for 12 hours. The surface of the dried product was then treated by stirring in an aqueous NaOH solution for 24 hours. Upon completion, the product was washed with deionized water (three times) and dried under vacuum at 120 °C for 12 hours to obtain the final product as a white solid.

[0064] 2. Characterization of Zirconium-Based Metal-Organic Framework Examples The zirconium-based metal-organic framework examples (Examples 1-3) with different types of linking ligands prepared as described above were further characterized using powder X-ray diffraction (XRD) to confirm the structure of the synthesized zirconium-based metal-organic frameworks, and nitrogen adsorption measurements (N adsorption) to characterize the porosity, average BET surface area, and pore volume of these examples.

[0065] 2.1. Analysis results by powder X-ray diffraction Figure 1(a) shows the XRD patterns of Example 1 obtained in the preparation of two separate batches of the gel-form product consisting of nanoparticles of the material. The gel-like state is one of the key features that distinguishes it from typical metal-organic frameworks, which are usually synthesized as fine crystals or powders. Figure 1(a) shows the gel-form of the material, as can be seen from the broad peaks.

[0066] One advantage of the gel form of the material is that it is a stable and viscous liquid, making it easier to use than powdered materials that need to be formed into granules before use.

[0067] Furthermore, a small peak was also observed at 2θ=6.5°, which is a diffraction peak from a defect site in the structure of the metal organic framework of Example 1. This peak at this position is not observed in the simulation pattern of an ideal UiO-66 crystal.

[0068] Figure 1(b) and Figure 1(c) show the XRD patterns of Example 2 and Example 3, respectively, obtained from the preparation of two separate batches. It can be observed that in Example 3, three additional peaks from structural defect sites were found at 2θ = approximately 7°, suggesting that the Zr nodes of Example 3 have many structural defects.

[0069] Furthermore, from the XRD patterns of the three examples, peaks were found at 2θ = approximately 7° to 9°, corresponding to the diffraction planes (111) and (200) of the six zirconium atom cluster (Zr6 cluster). This indicates that the tetravalent zirconium ions (Zr 4+ ) is in the form of a cluster of six zirconium atoms.

[0070] 2.2. Analysis results by nitrogen adsorption method Figure 2(a) shows the type IV nitrogen adsorption / desorption isotherm of Example 1, which was evaluated as a microporous material with mesopores due to the gel morphology of the material. The characteristics of the type IV nitrogen adsorption / desorption isotherm have a positive effect on the adsorption of arsenic compounds, especially arsenate (As(V), which is usually in the form of a large oxidized compound such as H3AsO4, which requires a larger surface area inside the adsorbent).

[0071] Figures 2(b) and 2(c) show the nitrogen adsorption-desorption isotherms of Type I for Examples 2 and 3, respectively. Example 2 exhibits reduced gas adsorption compared to Example 1 as a result of the smaller size of the linking ligands in the structure of Example 2.

[0072] 3 shows the nitrogen adsorption / desorption isotherms for Example 1, which is a zirconium-based metal-organic framework that differs from Comparative Examples A and B, which have the same type of linking ligands. The Comparative Examples are described in detail below.

[0073] The analysis results of the average BET surface area and pore volume of Examples 1 to 3 and Comparative Example are shown in Table 1. However, Comparative Example A and Comparative Example B are as follows. 1. Comparative Example A is a commercially available zirconium-based metal-organic framework (UiO-66), 2. Comparative Example B is a commercially available zirconium-based metal organic framework (UiO-66) that has been surface-treated for 24 hours with an aqueous sodium hydroxide solution whose pH is controlled in the range of 7 to 12.

[0074] [Table 1]

[0075] 3. Study on the effect of pH of sodium hydroxide solution According to the present invention, the adsorption efficiency of arsenic (As) and mercury (Hg) compounds is improved or enhanced by treating the surface of the material with an aqueous solution of an alkali metal hydroxide, for example, sodium hydroxide, to increase the amount of hydroxyl groups (—OH) on the surface of the zirconium-based metal-organic framework according to the present invention. When the amount of hydroxyl groups is increased in this way, the number of arsenic-specific active sites increases due to the oxygen-philicity of arsenic, which easily forms bonds with oxygen atoms.

[0076] This experiment was conducted to further study the effect of pH of the aqueous sodium hydroxide solution used in the surface treatment step of the zirconium-based metal-organic framework according to the method of the present invention by comparing the adsorption efficiency of arsenic compounds of exemplary zirconium-based metal-organic frameworks obtained using aqueous sodium hydroxide solutions with different pHs of 7, 8, 9, and 10. In the experiment, the pH of the aqueous sodium hydroxide solution before addition to the dried exemplary zirconium-based metal-organic framework in step (c) (referred to herein as pH before treatment) was NaOH aq ) and a portion of the aqueous sodium hydroxide solution during the surface treatment (represented as pH NaOH aq The pH of the solution was measured. The surface treatment was carried out at ambient temperature for 24 hours.

[0077] The initial removal of arsenic compounds in water was tested using an example of a zirconium-based metal-organic framework obtained by using aqueous sodium hydroxide solutions of different pH values. The details are as follows:

[0078] Test Method 1. A test example zirconium-based metal-organic framework according to the present invention was activated by heating at a temperature of 150° C. under vacuum for 24 hours. 2. 2 mg of the activated metal-organic framework was added to a 20 ml flask. 3. 10 ml of an aqueous solution containing either As(III) or As(V) was added to the flask and allowed to stand for 1 hour. 4. The zirconium-based metal-organic framework example was extracted by centrifugation at 12,000 rpm for 5 minutes. 5. The concentration of arsenic compounds remaining in the aqueous solution was measured using graphite furnace atomic absorption spectrometry (GFAAS), and the concentration of mercury compounds remaining in the aqueous solution was measured using a mercury analyzer. 6. The removal rate (%) of arsenic compounds was calculated by comparing the amount of As(III) or As(V) before and after adsorption using the example zirconium-based metal organic framework, and the arsenic compound adsorption capacity, which is the amount of arsenic compounds adsorbed (mg) relative to the amount of adsorbent used (g), was determined. The experimental results are shown in Table 2.

[0079] [Table 2]

[0080] The experimental results in Table 2 show that the zirconium-based metal-organic framework examples prepared by treatment with aqueous sodium hydroxide solutions at pH 7 to 10 have good removal capabilities for arsenic compounds, namely As(III) and As(V). The zirconium-based metal-organic framework examples prepared by treatment with aqueous sodium hydroxide solutions at pH 7 and 8 had the highest arsenic removal capabilities.

[0081] Furthermore, the initial adsorption efficiencies of arsenic compounds, namely As(III) and As(V), in water of the zirconium-based metal organic frameworks of the present invention in Examples and Comparative Examples were compared according to the above test method. The experimental results are shown in Table 3 below.

[0082] Explanation of the metal-organic framework examples used in the experiment 1. Example 1 is a zirconium-based metal-organic framework having 1,4-benzenedicarboxylic acid as a ligand, prepared according to the method of the present invention. 2. Example 2 is a zirconium-based metal-organic framework having but-2-enedioic acid as a ligand, prepared according to the method of the present invention. 3. Comparative Example A is a commercially available zirconium-based metal-organic framework (UiO-66) with 1,4-benzenedicarboxylic acid as the linking ligand. 4. Comparative Example B is a commercially available zirconium-based metal-organic framework (UiO-66) having 1,4-benzenedicarboxylic acid as a linking ligand, which was further surface-treated for 24 hours with an aqueous sodium hydroxide solution whose pH was controlled in the range of 7 to 12. 5. Comparative Example C is a commercially available zirconium-based metal-organic framework (UiO-67) with biphenyl-4,4'-dicarboxylic acid as the linking ligand.

[0083] [Table 3]

[0084] The experimental results showed that, when comparing structures with the same type of metal center and linking ligand, surface treatment with an aqueous sodium hydroxide solution at pH 7-12 (Examples 1-3 and Comparative Example B) significantly improved or enhanced the adsorption capacity of the zirconium-based metal-organic framework for arsenic compounds, particularly As(III), compared to an example without surface treatment (Comparative Example A). However, Examples 1 and 2, which were prepared using the chemicals, ratios, and specific steps of the method of the present invention, showed higher arsenic compound removal rates (%), with Example 1 showing the highest removal rates (%) for As(III) and As(V).

[0085] 4. Test on adsorption efficiency of arsenic and mercury compounds in condensate The adsorption efficiency of arsenic and mercury compounds in example condensates obtained from two different sources was tested using adsorbents, namely, example zirconium-based metal-organic frameworks prepared according to the method of the present invention (Examples 1-3) and Comparative Examples A-G, which are metal-organic frameworks containing different types of metal centers and linking ligands. The details are as follows:

[0086] Explanation of the metal-organic framework examples used in the experiment 1. Example 1 is a zirconium-based metal-organic framework having 1,4-benzenedicarboxylic acid as a ligand, prepared according to the method of the present invention. 2. Example 2 is a zirconium-based metal-organic framework having but-2-enedioic acid as a ligand, prepared according to the method of the present invention. 3. Example 3 is a zirconium-based metal-organic framework having 1,3,5-benzenetricarboxylic acid as a ligand, prepared according to the method of the present invention. 4. Comparative Example A is a commercially available zirconium-based metal-organic framework (UiO-66) with 1,4-benzenedicarboxylic acid as the linking ligand. 5. Comparative Example C is a commercially available zirconium-based metal-organic framework (UiO-67) with biphenyl-4,4'-dicarboxylic acid as the linking ligand. 6. Comparative Example D is a manganese-based metal-organic framework (Mn-MOF) with 2,5-dioxide-1,4-benzenedicarboxylate as the linking ligand. 7. Comparative Example E is an iron-based metal-organic framework having 1,3,5-benzenetricarboxylic acid as a linking ligand, which is subjected to a surface treatment for 24 hours with an aqueous sodium hydroxide solution whose pH is controlled in the range of 8 to 12.

[0087] Test Method 1. Test metal-organic framework examples (the above-mentioned Examples 1 to 3 and Comparative Example) were activated by heating at a temperature of 150° C. for 24 hours under vacuum. 2. 50 mg of the activated metal-organic framework example was added to a 100 ml flask. 3.37 ml of condensate was added to the flask and allowed to stand for 1 hour. 4. The zirconium-based metal-organic framework example was extracted by centrifugation at 12,000 rpm for 5 minutes. 5. The concentration of arsenic compounds remaining in the condensate was measured using graphite furnace atomic absorption spectrometry (GFAAS), and the concentration of mercury compounds remaining in the aqueous solution was measured using a mercury analyzer. 6. The adsorption capacity of arsenic compounds and mercury compounds was calculated from the amount of arsenic compounds or mercury compounds adsorbed (mg) relative to the amount of adsorbent used (g). 7. The removal rates (%) of arsenic compounds and mercury compounds were calculated by comparing the amounts of arsenic compounds and mercury compounds before and after adsorption by the example zirconium-based metal organic framework.

[0088] Test results Table 4 shows the test results for the adsorption efficiency of arsenic and mercury compounds in example condensates obtained from Sources 1 and 2 using different types of metal-organic frameworks (the above-mentioned Examples 1 to 3 and Comparative Example) as adsorbents.

[0089] [Table 4]

[0090] From the above experimental results, when comparing the zirconium-based metal-organic frameworks (i.e., Examples 1 to 3 and Comparative Examples A and C), it was found that the zirconium-based metal-organic framework according to the present invention exhibited significantly better adsorption efficiency of arsenic compounds in condensate (from both Sources 1 and 2) than the Comparative Examples. That is, when considering structures having the same type of linking ligand, in Example 1, the removal rate (%) of arsenic compounds in condensate from Source 1 was up to about 85%, and in condensate from Source 2 it was up to about 71%, while in Comparative Example A, the removal rate (%) of arsenic compounds in condensate from Source 1 was about 52%, and in condensate from Source 2 it was about 54%. From these results, it is clear that the method for preparing a zirconium-based metal-organic framework according to the present invention can significantly improve the adsorption efficiency of arsenic compounds.

[0091] When structures having different types of linking ligands were considered, in Comparative Example C, the removal rate (%) of arsenic compounds in the condensate from Source 1 was about 48%, and from Source 2 it was about 36%, whereas in Examples 1 to 3, the removal rate (%) of arsenic compounds in the condensate from Source 1 was about 85% (Example 1), about 73% (Example 2), and about 71% (Example 3), and in the condensate from Source 2 it was about 72% (Example 1), about 61% (Example 2), and about 67% (Example 3).

[0092] Furthermore, when comparing metal-organic frameworks having different types of metal centers and / or linking ligands (i.e., Examples 1 to 3 and Comparative Examples D and E), it was found that the zirconium-based metal-organic frameworks according to the present invention (Examples 1 to 3) had significantly higher removal rates (%) of arsenic compounds in condensates from both Sources 1 and 2 than the Comparative Examples.

[0093] For example, when structures having the same type of linking ligand but different types of metal centers are considered, it was found that the removal rate (%) of arsenic compounds in the condensate from Source 2 was about 67% in Example 3 (metal center was zirconium), while the removal rate (%) of arsenic compounds in the condensate from Source 2 was about 45% in Comparative Example E (metal center was iron). These results clearly demonstrate that the metal-organic framework having a zirconium metal center according to the present invention has significantly superior adsorption efficiency for arsenic compounds compared to metal-organic frameworks having other types of metal centers.

[0094] Best Mode for Carrying Out the Invention The best mode of the present invention is as described in the detailed description of the invention. The present disclosure also includes the following aspects. <1> Tetravalent zirconium ions (Zr 4+ ) and the tetravalent zirconium ion (Zr 4+ and a bidentate or tridentate linking ligand binding a zirconium-based metal-organic framework (MOR) to a heavy metal sorbent. <2> The surface is treated with an alkali metal hydroxide solution. <1> The zirconium-based metal organic structure according to claim 1. <3> The pH of the alkali metal hydroxide solution is controlled in the range of 7 to 12, preferably in the range of 7 to 8. <2> The zirconium-based metal organic structure according to claim 1. <4> 4. The surface treatment with the alkali metal hydroxide solution is carried out at ambient temperature for 12 to 36 hours. <2> or <3> The zirconium-based metal organic structure according to claim 1. <5> 10. The method of claim 9, wherein the alkali metal hydroxide is selected from the group consisting of sodium hydroxide, potassium hydroxide, and mixtures thereof. <2> ~ <4> 1. The zirconium-based metal organic framework according to any one of . <6> 10. The method of claim 9, wherein the linking ligand is selected from the group consisting of 1,4-benzenedicarboxylic acid, 1,3,5-benzenetricarboxylic acid, but-2-enedioic acid, and mixtures thereof. <1> The zirconium-based metal organic structure according to claim 1. <7> The tetravalent zirconium ions (Zr 4+ ) is derived from zirconium tetrachloride, zirconium oxychloride, zirconium oxychloride octahydrate, zirconium dioxide, zirconium tetrahydroxide, or a mixture thereof. <1> The zirconium-based metal organic structure according to claim 1. <8> A cluster node of six zirconium atoms (Zr 6 cluster nodes) and eight oxygen atoms partially linked to said linking ligands. <1> ~ <7> 1. The zirconium-based metal organic framework according to any one of . <9> The tetravalent zirconium ions (Zr 4+ ) to said linking ligand is in the range of 1:1 to 3. <1> ~ <8> 1. The zirconium-based metal organic framework according to any one of . <10> Average BET surface area of ​​300-1000m 2 / g range. <1> ~ <9> 1. The zirconium-based metal organic framework according to any one of . <11> Average pore volume of 0.2 to 1.2 cm 3 / g range. <1> ~ <9> 1. The zirconium-based metal organic framework according to any one of . <12> The average pore diameter is in the range of 3 to 5 nm. <1> ~ <9> 1. The zirconium-based metal organic framework according to any one of . <13> having a type I or type IV nitrogen adsorption / desorption isotherm; <1> ~ <9> 1. The zirconium-based metal organic framework according to any one of . <14> Claims: For use as an arsenic adsorbent in condensate. <1> ~ <13> 1. The zirconium-based metal organic framework according to any one of . <15> Claims: For use as a mercury adsorbent in condensate <1> ~ <13> 1. The zirconium-based metal organic framework according to any one of . <16> Claim <1> ~ <15> An adsorbent comprising the zirconium-based metal-organic framework according to any one of the above. <17> (a) preparing a reaction mixture in a solvent comprising a zirconium compound, a linking ligand, and optionally a modifier; (b) heating the reaction mixture obtained in step (a) at a temperature in the range of 80 to 150°C for 6 to 48 hours; (c) washing the reaction product obtained in step (b) with a solvent and drying the reaction product at a temperature in the range of 80 to 150°C for 6 to 15 hours; 1. A method for preparing a zirconium-based metal-organic framework for use as a heavy metal adsorbent in condensate, comprising: <18> and (d) contacting the reaction product obtained in step (c) with an aqueous alkali metal hydroxide solution at ambient temperature for 12 to 36 hours. <17> The method described below. <19> In step (d), the pH of the aqueous alkali metal hydroxide solution is controlled in the range of 7 to 12, preferably in the range of 7 to 8. <18> The method described below. <20> In step (d), the alkali metal hydroxide is selected from the group consisting of sodium hydroxide, potassium hydroxide, and mixtures thereof. <18> or <19> The method described below. <21> and (e) washing the product obtained in step (d) with a solvent and drying the product at a temperature in the range of 80 to 150° C. for 6 to 12 hours. <18> ~ <20> 10. The method according to claim 9, wherein <22> In step (e), the solvent is water. <21> The method described below. <23> In step (a), the molar ratio of the zirconium compound to the linking ligand is in the range of 1:1 to 3. <17> The method described below. <24> In step (a), the molar ratio of the zirconium compound to the modifier is in the range of 1:4-6. <17> The method described below. <25> In step (a), the molar ratio of the zirconium compound to the modifier is in the range of 1:300-400. <17> The method described below. <26> (a) preparing a reaction mixture comprising the zirconium compound and the linking ligand in a solvent; (b) heating the reaction mixture obtained in step (a) at a temperature in the range of 100 to 150°C for 12 to 36 hours; (c) washing the reaction product obtained in step (b) with a solvent and drying the reaction product at a temperature in the range of 100 to 150°C for 6 to 15 hours; (d) contacting the reaction product obtained in step (c) with an aqueous alkali metal hydroxide solution having a pH controlled in the range of 7 to 12 at ambient temperature for 12 to 36 hours; (e) washing the product obtained in step (d) with a solvent and drying the product at a temperature in the range of 80 to 150°C for 6 to 12 hours; In step (a), the molar ratio of the zirconium compound to the linking ligand is 1 : 1 to 3, <17> ~ <25> 10. The method according to claim 9, wherein <27> (a) preparing the reaction mixture in a solvent, the reaction mixture comprising the zirconium compound, the linking ligand, and the modifier; (b) heating the reaction mixture obtained in step (a) at a temperature in the range of 80 to 150°C for 24 to 48 hours; (c) washing the reaction product obtained in step (b) with a solvent and drying the reaction product at a temperature in the range of 100 to 150°C for 6 to 12 hours; (d) contacting the reaction product obtained in step (c) with an aqueous solution of an alkali metal hydroxide having a pH controlled in the range of 7 to 12 at ambient temperature for 12 to 36 hours; (e) washing the product obtained in step (d) with a solvent and drying the product at a temperature in the range of 80 to 150°C for 6 to 12 hours; In step (a), the molar ratio of the zirconium compound to the linking ligand is in the range of 1:1 to 1:3; In step (a), the molar ratio of the zirconium compound to the modifier is in the range of 1:300-400. Claim <16> ~ <25> 10. The method according to claim 9, wherein <28> (a) preparing the reaction mixture in a solvent, the reaction mixture comprising the zirconium compound, the linking ligand, and the modifier; (b) heating the reaction mixture obtained in step (a) at a temperature in the range of 90 to 110°C for 4 to 8 hours; (c) washing the reaction product obtained in step (b) with a solvent and drying the reaction product at a temperature in the range of 80 to 150°C for 6 to 12 hours; In step (a), the molar ratio of the zirconium compound to the linking ligand is in the range of 1:1 to 1:3; In step (a), the molar ratio of the zirconium compound to the modifier is in the range of 1:4 to 1:6. Claim <16> ~ <25> 10. The method according to claim 9, wherein <29> 10. The method of claim 9, wherein the zirconium compound is selected from the group consisting of zirconium tetrachloride, zirconium oxychloride, zirconium oxychloride octahydrate, zirconium dioxide, zirconium tetrahydroxide, and mixtures thereof. <17> ~ <28> 10. The method according to claim 9, wherein <30> 10. The method of claim 9, wherein the linking ligand is selected from the group consisting of 1,4-benzenedicarboxylic acid, 1,3,5-benzenetricarboxylic acid, but-2-enedioic acid, and mixtures thereof. <17> ~ <28> 10. The method according to claim 9, wherein <31> 2. The method of claim 1, wherein the modifier is selected from the group consisting of formic acid, acetic acid, propionic acid, and mixtures thereof. <17> ~ <28> 10. The method according to claim 9, wherein <32> In step (a), the solvent is selected from the group consisting of dimethylformamide, water, dimethyl sulfoxide (DMSO), methanol, ethanol, and mixtures thereof. <17> ~ <28> 10. The method according to claim 9, wherein <33> In step (c), the solvent is selected from the group consisting of dimethylformamide, acetone, methanol, ethanol, water, and mixtures thereof. <17> ~ <28> 10. The method according to claim 9, wherein <34> Condensate, <1> ~ <15> The zirconium-based metal containing mechanism according to any one of 1. A method for removing heavy metals from a condensate, comprising contacting the condensate with an adsorbent comprising a structure. <35> 2. The method of claim 1, wherein the contacting of the condensate with the adsorbent is carried out at a temperature in the range of 18 to 80° C. and a pressure in the range of 1 to 30 bar. <34> 2. A method for removing heavy metals according to claim 1.

Claims

1. Tetravalent zirconium ions (Zr ４＋ ) and the tetravalent zirconium ion (Zr ４＋ and a bidentate or tridentate linking ligand binding a zirconium-based metal-organic framework (MOR) to a heavy metal sorbent, the linking ligand is selected from the group consisting of 1,4-benzenedicarboxylic acid, 1,3,5-benzenetricarboxylic acid, but-2-enedioic acid, and mixtures thereof; the zirconium-based metal-organic framework has an average BET surface area in the range of 300 to 1000 m 2 / g; The zirconium-based metal organic framework has a hydroxy group on its surface. Zirconium-based metal-organic framework.

2. The tetravalent zirconium ion (Zr ４＋ 2. The zirconium-based metal-organic framework of claim 1, wherein the zirconium-based metal-organic framework is derived from any of zirconium tetrachloride, zirconium oxychloride, zirconium oxychloride octahydrate, zirconium dioxide, zirconium tetrahydroxide, or a mixture thereof.

3. A cluster node of six zirconium atoms (Zr ６ 2. The zirconium-based metal-organic framework of claim 1, comprising: a first oxygen atom (a cluster node) and eight oxygen atoms partially linked to said linking ligands.

4. The tetravalent zirconium ion (Zr ４＋ 2. The zirconium-based metal-organic framework of claim 1, wherein the molar ratio of the linking ligand to the linking ligand is in the range of 1:1-3.

5. Average pore volume is 0.2 to 1.2 cm ３ The zirconium-based metal-organic framework according to claim 1, wherein the Zr content is in the range of 1 / g.

6. The zirconium-based metal-organic framework according to claim 1, wherein the average pore diameter is in the range of 3 to 5 nm.

7. The zirconium-based metal-organic framework according to claim 1, having a type I or type IV nitrogen adsorption / desorption isotherm.

8. 10. The zirconium-based metal-organic framework of claim 1 for use as an arsenic adsorbent in condensate.

9. 10. The zirconium-based metal-organic framework of claim 1 for use as a mercury sorbent in condensate.

10. An adsorbent comprising the zirconium-based metal-organic framework according to any one of claims 1 to 9.

11. A method for producing a zirconium compound, a zirconium ion-containing compound, a linking ligand, and optionally a modifier, comprising the steps of: (a) preparing a reaction mixture in a solvent; (b) heating the reaction mixture obtained in step (a) at a temperature ranging from 80 to 150°C for a period of 6 to 48 hours; (c) washing the reaction product obtained in step (b) with a solvent and drying the reaction product at a temperature in the range of 80 to 150°C for 6 to 15 hours; (d) contacting the reaction product from step (c) with an aqueous alkali metal hydroxide solution at ambient temperature for 12 to 36 hours; Including, the linking ligand is selected from the group consisting of 1,4-benzenedicarboxylic acid, 1,3,5-benzenetricarboxylic acid, but-2-enedioic acid, and mixtures thereof; A method for preparing a zirconium-based metal-organic framework for use as a heavy metal adsorbent in condensates.

12. 12. The method according to claim 11, wherein in step (d), the pH of the aqueous alkali metal hydroxide solution is controlled in the range of 7 to 12.

13. The method of claim 11, wherein in step (d), the pH of the aqueous alkali metal hydroxide solution is controlled in the range of 7 to 8.

14. 12. The method of claim 11, wherein in step (d), the alkali metal hydroxide is selected from the group consisting of sodium hydroxide, potassium hydroxide, and mixtures thereof.

15. 12. The process of claim 11, further comprising the step (e) of washing the product obtained in step (d) with a solvent and drying the product at a temperature in the range of 80 to 150°C for 6 to 12 hours.

16. 16. The method of claim 15, wherein in step (e), the solvent is water.

17. 12. The method of claim 11, wherein the molar ratio of the zirconium compound to the linking ligand in step (a) is in the range of 1:1-3.

18. 12. The method of claim 11, wherein the molar ratio of the zirconium compound to the modifier in step (a) is in the range of 1:300-400.

19. (a) preparing a reaction mixture comprising the zirconium compound and the linking ligand in a solvent; (b) heating the reaction mixture obtained in step (a) at a temperature ranging from 100 to 150°C for 12 to 36 hours; (c) washing the reaction product obtained in step (b) with a solvent and drying the reaction product at a temperature in the range of 100 to 150°C for 6 to 15 hours; (d) contacting the reaction product obtained in step (c) with an aqueous alkali metal hydroxide solution having a pH controlled in the range of 7 to 12 at ambient temperature for 12 to 36 hours; (e) washing the product obtained in step (d) with a solvent and drying the product at a temperature in the range of 80 to 150°C for 6 to 12 hours; In step (a), the molar ratio of the zirconium compound to the linking ligand is 1 12. The method of claim 11, wherein the ratio of the number of saturates to the number of saturates is in the range of 1 to 3.

20. (a) preparing the reaction mixture comprising the zirconium compound, the linking ligand, and the modifier in a solvent; (b) heating the reaction mixture obtained in step (a) at a temperature ranging from 80 to 150°C for 24 to 48 hours; (c) washing the reaction product obtained in step (b) with a solvent and drying the reaction product at a temperature in the range of 100 to 150°C for 6 to 12 hours; (d) contacting the reaction product obtained in step (c) with an aqueous solution of an alkali metal hydroxide having a controlled pH in the range of 7 to 12 at ambient temperature for 12 to 36 hours; (e) washing the product obtained in step (d) with a solvent and drying the product at a temperature in the range of 80 to 150°C for 6 to 12 hours; In step (a), the molar ratio of the zirconium compound to the linking ligand is in the range of 1:1 to 3; In step (a), the molar ratio of the zirconium compound to the modifier is in the range of 1:300-400; The method of claim 11.

21. 21. The method of any one of claims 11 to 20, wherein the zirconium compound is selected from the group consisting of zirconium tetrachloride, zirconium oxychloride, zirconium oxychloride octahydrate, zirconium dioxide, zirconium tetrahydroxide, and mixtures thereof.

22. 21. The method of any one of claims 11 to 20, wherein the modifier is selected from the group consisting of formic acid, acetic acid, propionic acid, and mixtures thereof.

23. 21. The method of any one of claims 11 to 20, wherein in step (a), the solvent is selected from the group consisting of dimethylformamide, water, dimethyl sulfoxide (DMSO), methanol, ethanol, and mixtures thereof.

24. 21. The method of any one of claims 11 to 20, wherein in step (c), the solvent is selected from the group consisting of dimethylformamide, acetone, methanol, ethanol, water, and mixtures thereof.

25. The condensate is mixed with the zirconium-based metal containing mechanism according to any one of claims 1 to 9.

1. A method for removing heavy metals from a condensate, comprising contacting the condensate with an adsorbent comprising a structure.

26. 26. The method for removing heavy metals according to claim 25, wherein the contacting of the condensate with the adsorbent is carried out at a temperature in the range of 18 to 80° C. and a pressure in the range of 1 to 30 bar.

Images