JP2017014146A - Separation method of para-xylene using metal organic structure - Google Patents

Abstract

An object of the present invention is to provide a metal organic structure for separating paraxylene from an organic mixture containing paraxylene. Another object of the present invention is to provide a method for separating paraxylene from an organic mixture containing paraxylene using the metal organic structure. Furthermore, another object of the present invention is to provide a method for producing high-purity paraxylene using the metal organic structure. A metal organic structure for separating para-xylene comprising a Group 4 metal and an aliphatic carboxylic acid ligand. [Selection] Figure 9

Description

  The present invention relates to a method for separating para-xylene using a metal organic structure.

  In petrochemistry, naphtha is cracked to produce ethylene, propylene, and the like. At this time, an aromatic compound is simultaneously produced from naphtha. Among them, the fraction of the aromatic compound having 8 carbon atoms to be recovered contains four components of ethylbenzene, orthoxylene, metaxylene and paraxylene. Of these, it is well known that paraxylene is a very useful compound as a raw material for polyethylene terephthalate (PET). Up to now, it has been attempted to separate the above four components by a distillation method or a complicated column separation method (Patent Documents 1 and 2). However, these four components are close to each other in boiling point, and the difference in molecular size is also small. Therefore, separating only paraxylene from the four components has a problem in that energy consumption, equipment cost, and the like increase. It was.

JP 2013-53676 A JP 2008-518781

  An object of the present invention is to provide a metal organic structure for separating paraxylene from an organic mixture containing paraxylene. Another object of the present invention is to provide a method for separating paraxylene from an organic mixture containing paraxylene using the metal organic structure. Furthermore, another object of the present invention is to provide a method for producing high-purity paraxylene using the metal organic structure.

  As a result of intensive studies to achieve the above object, the present invention has found that a metal organic structure containing a Group 4 metal and an aliphatic carboxylic acid ligand can achieve the above object. As a result of further research based on these findings, the present invention has been completed.

That is, the present invention provides a metal organic structure for separation of paraxylene, a method for producing the metal organic structure for separation of paraxylene, which contains the following Group 4 metal and an aliphatic carboxylic acid ligand, Another object of the present invention is to provide a method for separating para-xylene from an organic mixture containing the same, and a method for producing high-purity para-xylene.
Item 1.
A method for separating para-xylene from an organic mixture containing para-xylene, comprising:
A method using a metal organic structure comprising a Group 4 metal and an aliphatic carboxylic acid ligand.
Item 2.
Item 2. The method according to Item 1, wherein the organic mixture containing para-xylene is an organic mixture containing an aromatic hydrocarbon having 8 carbon atoms.
Item 3.
Item 3. The method according to Item 1 or 2, wherein the Group 4 metal is at least one selected from the group of metals consisting of Ti, Zr, and Hf.
Item 4.
Item 4. The method according to any one of Items 1 to 3, wherein the aliphatic carboxylic acid ligand is an aliphatic dicarboxylic acid ligand, an aliphatic tricarboxylic acid ligand, or an aliphatic tetracarboxylic acid ligand. .
Item 5.
The aliphatic carboxylic acid ligand is
A saturated or unsaturated aliphatic dicarboxylic acid ligand having 2 to 7 carbon atoms,
Item 5 is a saturated or unsaturated aliphatic tricarboxylic acid ligand having 3 to 8 carbon atoms, or a saturated or unsaturated aliphatic tetracarboxylic acid ligand having 5 to 8 carbon atoms. The method described.
Item 6.
Item 6. The method according to any one of Items 1 to 5, wherein the aliphatic carboxylic acid ligand is a fumaric acid ligand or a maleic acid ligand.
Item 7.
A method for producing high purity para-xylene, comprising:
The manufacturing method including the process of isolate | separating paraxylene using the organic mixture containing a paraxylene, and the metal organic structure containing a group 4 metal and an aliphatic carboxylic acid ligand.
Item 8.
Item 8. The method according to Item 7, wherein the organic mixture containing para-xylene is an organic mixture containing an aromatic hydrocarbon having 8 carbon atoms.
Item 9.
Item 9. The method according to Item 7 or 8, wherein the Group 4 metal is at least one selected from the group of metals consisting of Ti, Zr, and Hf.
Item 10.
Item 10. The method according to any one of Items 7 to 9, wherein the aliphatic carboxylic acid ligand is an aliphatic dicarboxylic acid ligand, an aliphatic tricarboxylic acid ligand, or an aliphatic tetracarboxylic acid ligand. .
Item 11.
The aliphatic carboxylic acid ligand is
A saturated or unsaturated aliphatic dicarboxylic acid ligand having 2 to 7 carbon atoms,
In any one of Items 7 to 10, which is a saturated or unsaturated aliphatic tricarboxylic acid ligand having 3 to 8 carbon atoms, or a saturated or unsaturated aliphatic tetracarboxylic acid ligand having 5 to 8 carbon atoms. The method described.
Item 12.
Item 12. The method according to any one of Items 7 to 11, wherein the aliphatic carboxylic acid ligand is a fumaric acid ligand or a maleic acid ligand.
Item 13.
A metal organic structure for separation of para-xylene, comprising a Group 4 metal and an aliphatic carboxylic acid ligand.
Item 14.
Item 14. The metal organic structure for paraxylene separation according to Item 13, for separating paraxylene from a mixture containing an aromatic hydrocarbon having 8 carbon atoms.
Item 15.
Item 15. The metal organic structure for paraxylene separation according to Item 13 or 14, wherein the Group 4 metal is at least one selected from the group of metals consisting of Ti, Zr, and Hf.
Item 16.
Paragraph as described in any one of Items 13 to 15, wherein the aliphatic carboxylic acid ligand is an aliphatic dicarboxylic acid ligand, an aliphatic tricarboxylic acid ligand, or an aliphatic tetracarboxylic acid ligand. Metal organic structure for xylene separation.
Item 17.
The aliphatic carboxylic acid ligand is
A saturated or unsaturated aliphatic dicarboxylic acid ligand having 2 to 7 carbon atoms,
In any one of Items 13 to 16, which is a saturated or unsaturated aliphatic tricarboxylic acid ligand having 3 to 8 carbon atoms, or a saturated or unsaturated aliphatic tetracarboxylic acid ligand having 5 to 8 carbon atoms. Metal organic structure for separation of paraxylene as described.
Item 18.
Item 18. The organic metal structure for separating para-xylene according to any one of Items 13 to 17, wherein the aliphatic carboxylic acid ligand is a fumaric acid ligand or a maleic acid ligand.
Item 19.
Item 14. A method for producing a metal-organic structure for separation of paraxylene according to Item 13,
A production method comprising a step of reacting a Group 4 metal salt and an aliphatic carboxylic acid.
Item 20.
Item 20. The production method according to Item 19, wherein the Group 4 metal salt is at least one selected from the group of metals consisting of Ti, Zr, and Hf.
Item 21.
Item 21. The production method according to Item 19 or 20, wherein the aliphatic carboxylic acid is an aliphatic dicarboxylic acid, an aliphatic tricarboxylic acid, or an aliphatic tetracarboxylic acid.
Item 22.
The aliphatic carboxylic acid is
A saturated or unsaturated aliphatic dicarboxylic acid having 2 to 7 carbon atoms,
Item 22. The production method according to any one of Items 19 to 21, which is a saturated or unsaturated aliphatic tricarboxylic acid having 3 to 8 carbon atoms, or a saturated or unsaturated aliphatic tetracarboxylic acid having 5 to 8 carbon atoms.
Item 23.
Item 23. The production method according to any one of Items 19 to 22, wherein the aliphatic carboxylic acid is fumaric acid or maleic acid.

  ADVANTAGE OF THE INVENTION According to this invention, the metal organic structure which can selectively isolate | separate paraxylene from the organic mixture containing paraxylene can be provided. Moreover, according to this invention, the method of isolate | separating paraxylene from the organic mixture containing paraxylene using this metal organic structure can also be provided. Furthermore, the present invention can also provide a method for producing high-purity paraxylene using the metal organic structure.

FIG. 1 is a diagram showing the results of Test Example 1 using the metal organic structure of Example 1. FIG. FIG. 2 is a diagram showing the results of Test Example 1 using the metal organic structure of Comparative Example 1. FIG. 3 is a diagram showing the results of Test Example 1 using the metal organic structure of Comparative Example 2. FIG. 4 is a diagram showing the results of Test Example 1 using the metal organic structure of Comparative Example 3. FIG. 5 is a diagram showing the results of Test Example 1 using the metal organic structure of Comparative Example 4. 6 is a diagram showing the results of Test Example 1 using the metal organic structure of Comparative Example 5. FIG. FIG. 7 is a diagram showing the results of Test Example 1 using the metal organic structure of Comparative Example 6. FIG. 8 is a diagram showing the results of Test Example 1 using the metal organic structure of Comparative Example 7. FIG. 9 is a view showing the separation result of the xylene mixture of Test Example 1 using the metal organic structure of Example 1. FIG. FIG. 10 is a diagram showing the separation result of the xylene mixture of Test Example 1 using the metal organic structure of Comparative Example 1. FIG. 11 is a graph showing measurement results of powder X-ray diffraction, BET specific surface area, and pore size distribution using the metal organic structure of Example 1. 12 is a graph showing measurement results of powder X-ray diffraction, BET specific surface area, and pore size distribution using the metal organic structure of Comparative Example 1. FIG. FIG. 13 is a graph showing measurement results of powder X-ray diffraction, BET specific surface area, and pore size distribution using the metal organic structure of Comparative Example 2. FIG. 14 is a graph showing measurement results of powder X-ray diffraction, BET specific surface area, and pore size distribution using the metal organic structure of Comparative Example 3. FIG. 15 is a diagram showing measurement results of powder X-ray diffraction, BET specific surface area, and pore size distribution using the metal organic structure of Comparative Example 4. FIG. 16 is a graph showing measurement results of powder X-ray diffraction, BET specific surface area, and pore size distribution using the metal organic structure of Comparative Example 5. FIG. 17 is a graph showing measurement results of powder X-ray diffraction, BET specific surface area, and pore size distribution using the metal organic structure of Comparative Example 6. FIG. 18 is a diagram showing measurement results of powder X-ray diffraction, BET specific surface area, and pore size distribution using the metal organic structure of Comparative Example 7. FIG. 19 is a diagram showing a thermogravimetric analysis (TG) measurement result using the metal organic structure of Example 1. FIG.

1. Metal organic structure (MOF)
In the metal-organic structure of the present invention (Metal-Organic Framework, hereinafter sometimes referred to as “MOF”), a group 4 metal ion and an aliphatic carboxylate ligand form a coordinate bond. The basic structure is a continuous growth to particles. The metal organic structure thus obtained contains a Group 4 metal and an aliphatic carboxylic acid ligand, and the metal organic structure can selectively separate paraxylene from an organic mixture containing paraxylene. .

  In addition, the metal organic structure of the present invention may be referred to as a porous coordination polymer (hereinafter sometimes referred to as “PCP”). The porous coordination polymer (PCP) is sometimes collectively referred to as “MOF”.

Group 4 metal The metal of Group 4 may be a metal having at least two sites to which a ligand can coordinate. For example, titanium (Ti), zirconium (Zr), hafnium (Hf), etc. Is mentioned. A preferred Group 4 metal is zirconium.

  Group 4 metals may be used alone or in combination of two or more. Group 4 metals are present as metal ions in metal organic structures.

  The metal organic structure of the present invention can contain a metal atom other than the Group 4 metal.

The aliphatic carboxylic acid ligand is not particularly limited, and examples thereof include an aliphatic dicarboxylic acid ligand, an aliphatic tricarboxylic acid ligand, and an aliphatic tetracarboxylic acid ligand. Can be mentioned.

Here, the aliphatic carboxylic acid ligand means a compound having a carboxylate ion (COO ⁻ ) obtained by removing a hydrogen atom from a carboxylic acid (COOH) site in the aliphatic carboxylic acid. The aliphatic carboxylic acid ligand may have a side chain in addition to the main chain having the longest carbon chain length. The chain length of the main chain is preferably 2-8. The main chain may contain elements other than carbon atoms. Further, the side chain may be bonded to the main chain with a carbon atom and an element other than the carbon atom.

Examples of the aliphatic dicarboxylic acid ligand include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, propylmalonic acid, butylmalonic acid, heptylmalonic acid, dipropylmalonic acid, malic acid, tartaric acid, asparagine. Linear or branched saturated aliphatic dicarboxylic acid ligands which may be substituted via a hetero element such as acid, glutamic acid, iminodiacetic acid, thiodipropionic acid and thiomaleic acid ;
Linear or branched unsaturated dicarboxylic acids that may be substituted with a hetero-element such as maleic acid, fumaric acid, itaconic acid, citraconic acid, hexadiene diacid (muconic acid), etc. An acid ligand etc. are mentioned.

  Examples of the substituent bonded to the main chain include a hydroxyl group, an amino group, a sulfoxide group, a sulfone group, and an alkyl group (for example, an alkyl group having 1 to 6 carbon atoms).

  In the aliphatic dicarboxylic acid ligand, examples of the hetero element that may be interposed in the main chain include a nitrogen atom, an oxygen atom, and a sulfur atom.

  Examples of the aliphatic tricarboxylic acid ligand may include a hetero element such as tricarballylic acid, aconitic acid, citric acid, 1,2,3-butanetricarboxylic acid, and may have a substituent. Examples thereof include a linear or branched aliphatic tricarboxylic acid ligand.

  Examples of the aliphatic tetracarboxylic acid ligand include cyclobutanetetracarboxylic acid, 1,2,3,4-cyclopentanetetracarboxylic acid, 2,3,5,6-cyclohexanetetracarboxylic acid, 1,2,3. , 4-butanetetracarboxylic acid and the like, and a linear or branched aliphatic tetracarboxylic acid ligand which may have a substituent and may have a hetero element.

  Preferred aliphatic carboxylic acid ligands are aliphatic dicarboxylic acid ligands, more preferably aliphatic dicarboxylic acid ligands having 2 to 6 carbon atoms in the main chain, and even more preferably fumaric acid coordination. Ligands and maleic acid ligands, most preferably fumaric acid ligands.

  Although the metal organic structure of the present invention is also a porous material, its average pore diameter is usually 0.3 to 2 nm, preferably 0.3 to 1.5 nm, more preferably 0.4 to 1 nm.

  The pore diameter can be estimated by isotherm analysis of nitrogen adsorption / desorption or adsorption of probe molecules having a known molecular size.

  When the pore diameter is in the above range, only x-xylene selectively passes through the pores in the metal organic structure in the xylene mixture, and other meta-xylene and ortho-xylene do not pass through the pores. It is presumed to pass through the metal organic structure.

  The average particle diameter of the metal organic structure is about 10 nm to 20 μm, preferably about 50 nm to 10 μm.

The BET specific surface area of the metal organic structure is about 500 to about 2000 m ² / g, preferably about 800 to about 1200 m ² / g, and more preferably about 1000 m ² / g.

  The metal organic structure is manufactured in a powder form. For this reason, the powder may be used as it is, or the powder may be molded and used. In molding, there is no particular limitation on the shape, and it can be molded into any shape such as a spherical shape or a cylindrical shape. In molding, a known molding aid may be added.

  A divalent or higher valent aliphatic carboxylic acid ligand is a complex spread in one, two, or three dimensions by coordinating to two separate metal ions. In the metal organic structure used in the production method of the present invention, the unit cell of the metal organic structure is polymerized in at least one dimension. In other words, two or more metal ions are coordinated to one aliphatic carboxylic acid ligand. It is necessary to. Such metal organic structures include MOF, PCP, etc., but do not include mononuclear complexes.

  In the present specification, the expression “containing” or “including” includes the concepts “containing”, “including”, “consisting essentially only”, and “consisting only”.

2. Method for Producing Metal Organic Structure The method for producing a metal organic structure of the present invention includes a step of reacting a metal salt of Group 4 and an aliphatic carboxylic acid. Furthermore, the reaction in this step can be performed in water and / or an organic solvent in the presence of a modulator, if necessary.

  Metal ions from the fourth metal salt form a metal organic structure. Examples of such metal ions include metal ions of metals belonging to Group 4 of the periodic table, specifically titanium ions and zirconium ions. And metal ions such as hafnium ions, preferably zirconium ions.

  The metal ion is obtained from a metal salt containing a Group 4 metal element, and the metal salt containing the Group 4 metal element is not particularly limited, and examples thereof include metal chlorides, metal bromides, and metal iodides. And metal halides such as metal fluorides; metal nitrates; metal sulfates; metal carbonates; metal formates; metal phosphates; metal sulfides; The metal salt containing a Group 4 metal element is preferably a metal nitrate or metal chloride.

  Specific examples of Group 4 metal salts include metal halides belonging to Group 4 such as zirconium chloride, titanium chloride, zirconium oxide chloride, titanium oxide chloride; zirconium nitrate, titanium nitrate, zirconium oxide nitrate, nitric oxide Examples thereof include nitrates such as titanium. A preferred metal salt containing a Group 4 metal element is zirconium chloride.

  As the metal ion, a single metal ion can be used, or two or more metal ions can be used in combination.

  There is no restriction | limiting in particular as aliphatic carboxylic acid, For example, aliphatic dicarboxylic acid, aliphatic tricarboxylic acid, aliphatic tetracarboxylic acid etc. are mentioned.

  The aliphatic carboxylic acid may have a side chain in addition to the main chain having the longest carbon chain length. The chain length of the main chain is preferably 2-8. The main chain may contain elements other than carbon atoms. Further, the side chain may be bonded to the main chain with a carbon atom and an element other than the carbon atom.

Examples of the aliphatic dicarboxylic acid include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, propylmalonic acid, butylmalonic acid, heptylmalonic acid, dipropylmalonic acid, malic acid, tartaric acid, aspartic acid, glutamic acid. A linear or branched saturated aliphatic dicarboxylic acid which may be substituted by a hetero element and may have a substituent such as iminodiacetic acid, thiodipropionic acid and thiomaleic acid;
Linear or branched unsaturated dicarboxylic acids that may be substituted with a hetero-element such as maleic acid, fumaric acid, itaconic acid, citraconic acid, hexadiene diacid (muconic acid), etc. An acid etc. are mentioned.

  Examples of the substituent bonded to the main chain include a hydroxyl group, an amino group, a sulfoxide group, a sulfone group, and an alkyl group (for example, an alkyl group having 1 to 6 carbon atoms).

  In the aliphatic dicarboxylic acid, examples of the hetero element which may be interposed in the main chain include a nitrogen atom, an oxygen atom and a sulfur atom.

  As the aliphatic tricarboxylic acid, for example, a linear chain which may be substituted with a hetero element such as tricarballylic acid, aconitic acid, citric acid, 1,2,3-butanetricarboxylic acid, etc. And aliphatic aliphatic tricarboxylic acids and the like.

  Examples of the aliphatic tetracarboxylic acid include cyclobutanetetracarboxylic acid, 1,2,3,4-cyclopentanetetracarboxylic acid, 2,3,5,6-cyclohexanetetracarboxylic acid, 1,2,3,4- Examples thereof include a linear or branched aliphatic tetracarboxylic acid which may be introduced through a hetero element and may have a substituent, such as butanetetracarboxylic acid.

  Preferred aliphatic carboxylic acids are aliphatic dicarboxylic acids, more preferably aliphatic dicarboxylic acids having 2 to 6 carbon atoms in the main chain, more preferably fumaric acid and maleic acid, and most preferably fumaric acid. It is an acid.

  The amount of the aliphatic carboxylic acid used can be appropriately selected from a wide range. For example, it is usually 0.1 to 100 mol, preferably 0.5 to 50 mol, relative to 1 mol of the metal salt of Group 4 It is.

  In the production method of the present invention, when an organic solvent is used, the organic solvent may be a metal salt and / or aliphatic carboxylic acid suspended or at least partially dissolved when the metal organic structure is formed. There is no particular limitation. Examples of such organic solvents include aliphatic hydrocarbons such as pentane, hexane, and heptane; aromatic hydrocarbons such as benzene, toluene, and xylene; dichloromethane, chloroform, 1,2-dichloroethane, 1,1,1- Halogenated hydrocarbons such as trichloroethane, trichlorethylene and carbon tetrachloride; ethers such as isopropyl ether, tetrahydrofuran and dioxane; N, N-dimethylformamide (DMF), N, N-dimethylacetamide, 1,3-dimethylimidazolidinone and the like Amides; sulfoxides such as dimethyl sulfoxide; nitriles such as acetonitrile and propanenitrile; or a mixed solvent thereof. A preferred organic solvent is DMF.

  In the case of using a solvent, the amount used can be appropriately selected from a wide range. For example, it is usually 0.01 to 500 liters, preferably 0.1 to 30 liters per mole of aliphatic carboxylic acid. is there.

  When an acid is used as the modulator, examples of the acid include organic acids such as formic acid and acetic acid. A preferred organic acid is formic acid.

  In the production method of the present invention, when an acid is used, the amount used can be appropriately selected from a wide range. For example, it is usually 0.1 to 100 mol, preferably 1 mol to 1 mol of an aliphatic carboxylic acid. 1 to 30 moles.

  The reaction temperature in the production method of the present invention is about 30 to 500 ° C, preferably about 50 to 400 ° C, more preferably about 70 to 300 ° C, and further preferably about 100 to 200 ° C.

  When water and / or an organic solvent is used as the solvent, the pressure may exceed normal pressure depending on the reaction temperature in the production method of the present invention. In this case, the metal organic structure of the present invention can be produced using a pressure vessel (such as an autoclave). There is no restriction | limiting in particular as the container, A stainless steel airtight container, a pressure-resistant specification glass airtight container, etc. are mentioned.

  The production method of the present invention can be carried out in an atmosphere of an inert gas such as nitrogen or argon, or in an atmosphere containing oxygen.

  When water is produced by the production method of the present invention, the metal organic structure can be produced while removing water.

  The reaction pressure in the production method of the present invention is about 10 MPa or less, preferably about 5 MPa or less, particularly preferably about 3 MPa.

  The reaction time in the production method of the present invention is not particularly limited, and is usually about 1 minute to 30 days, preferably about 1 hour to 72 hours.

  After completion of the reaction in the production method of the present invention, unreacted raw material compounds, by-products, etc. are removed from the resulting reaction mixture by usual purification methods such as washing (water, acetone, etc.), filtration, and centrifugation. The target metal organic structure can be taken out.

3. Paraxylene separation method and high-purity paraxylene production method The paraxylene separation method of the present invention is a method for separating paraxylene from an organic mixture containing paraxylene, which comprises a Group 4 metal and an aliphatic carboxylic acid. This is a method using a metal organic structure containing a ligand.

  The method for producing high-purity para-xylene according to the present invention separates para-xylene using an organic mixture containing para-xylene and a metal organic structure containing a Group 4 metal and an aliphatic carboxylic acid ligand. It is a manufacturing method including a process.

  The organic mixture containing para-xylene (hereinafter sometimes referred to as “raw material mixture”) is not particularly limited, and examples thereof include organic mixtures obtained from naphtha cracking in the petrochemical industry, mixed xylenes in petroleum refining, and the like. It is done. Among them, a preferable raw material mixture is a mixture containing an aromatic hydrocarbon having 8 carbon atoms, more preferably paraxylene (p-xylene), metaxylene (m-xylene), orthoxylene (o-xylene), and A mixture containing ethylbenzene.

In this raw material mixture,
The content of para-xylene is usually 15-20% by weight;
The content of meta-xylene is usually 40% by weight;
The content of ortho-xylene is usually 15-25% by weight;
The content of ethylbenzene is usually 15 to 30% by weight.

  The raw material mixture may contain aromatic hydrocarbons other than those having 8 carbon atoms, such as benzene and cumene.

  In the present invention, paraxylene can be selectively separated from an organic mixture containing paraxylene by using the metal organic structure described above. That is, the amount of paraxylene can be improved from the organic mixture mainly containing aromatic hydrocarbons having 8 carbon atoms such as paraxylene, metaxylene, orthoxylene, ethylbenzene, etc., and high purity paraxylene can be produced. . Since ethylbenzene can be relatively easily separated from paraxylene by distillation, there is essentially no problem even if ethylbenzene is contained in paraxylene.

  Therefore, in the present invention, a paraxylene separation process with high apparatus efficiency can be provided by the metal organic structure.

  The separation method of the present invention is not particularly limited, and various methods can be mentioned. Typical separation methods include a separation method using the difference in adsorptivity between paraxylene and other components; a method of separating the remaining components by passing paraxylene through the pores in the metal organic structure, etc. Is mentioned.

  Examples of the separation method using the difference in adsorptivity include a gas phase method and a liquid phase method. When implementing a liquid phase method, the separation method including an adsorption process and a desorption process is mentioned. The temperature in the adsorption step and desorption step is usually room temperature to 200 ° C, preferably room temperature to 180 ° C. The pressure in the adsorption step and the desorption step may be a pressure sufficient to keep the system in a liquid phase state. The adsorptive separation method of the present invention is carried out by a chromatographic method, and can be carried out by any method such as a fixed bed, a fluidized bed, a moving bed, etc. Among them, it is preferably industrially carried out by a simulated moving bed method. . Adsorption separation by a simulated moving bed system is an established technology. When the gas phase method is carried out, it can be carried out by the same method as the liquid phase method.

  An example of a method for separating paraxylene by passing through pores in the metal organic structure is a membrane separation method. In this case, a self-supporting film or a metal organic structure formed on a support can be used.

4). Use of Metal Organic Structure The metal organic structure of the present invention can be used for the purpose of selectively separating paraxylene from an organic mixture containing paraxylene. In particular, the metal organic structure of the present invention can be used for the purpose of selectively separating para-xylene from an organic mixture containing an aromatic hydrocarbon having 8 carbon atoms.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, the scope of the present invention is not limited by these Examples.

<Powder X-ray diffraction>
Using a powder X-ray diffractometer (RINT2000 manufactured by Rigaku Corporation, light source CuKα, tube voltage 40 kV, tube current 20 mA), a scanning angle of 0.01 °, a scanning speed of 4 ° / min, and a vertical divergence range of 2θ = 3-50 ° The measurement was performed at room temperature under the conditions of a limiting slit of 10 mm, a divergence slit of 1/3 °, a light receiving slit of 0.3 mm, and a scattering slit of 1/3 °.

<BET specific surface area, pore size distribution>
A nitrogen adsorption / desorption isotherm was measured by a constant-volume gas adsorption method using a nitrogen adsorption / desorption measurement apparatus (manufactured by Microtrac BEL, BELSORP-mini) to give a sample of 0.02 g, and nitrogen gas as an adsorption gas. The specific surface area was analyzed by the BET method, and the micropore pore distribution was analyzed by the MP method. Pretreatment before measurement was performed at 200 ° C. for 1 hour in a nitrogen atmosphere.

<Thermogravimetry TG>
Using a differential thermogravimetric analyzer (manufactured by Rigaku, Thermo plus EV02), about 15 mg of the metal organic structure powder was heated from room temperature to 800 ° C. at a heating rate of 5 ° C./min under air flow (300 mL / min). Measured in the temperature range up to.

Example 1: Preparation of MOF-801 (metal: Zr, aliphatic carboxylic acid ligand: fumaric acid ) 2.60 mmol of zirconium tetrachloride (ZrCl ₄ ), 8.35 mmol of fumaric acid, 3 mL of formic acid (HCOOH), and dimethylformamide ( DMF) 20 mL was weighed in order into a 50 mL beaker and stirred for 10 minutes. The obtained mixture was put into a 50 mL stainless steel autoclave whose inner surface was Teflon-treated, and then replaced with nitrogen four times to make the inside an atmospheric atmosphere of nitrogen. Thereafter, the temperature was raised from room temperature to 120 ° C. over 1 hour, kept at 120 ° C. for 24 hours, and then allowed to cool to room temperature. The solid was centrifuged under conditions of 5000 rpm and 10 minutes, and ultrasonic washing and centrifugation were performed under conditions of 28 kHz and 10 minutes respectively with 50 mL of acetone, 50 mL of methanol, and then 50 mL of pure water to obtain a product. Then, it was dried overnight at 80 ° C., and further dried at 200 ° C. for 2 hours under reduced pressure of 20 hPa to obtain 0.54 g of the desired product (91% yield based on Zr).
Specific surface area: 930 m ² / g
Average pore diameter: 0.6 nm

Comparative Example 1: Preparation of UiO-66 (metal: Zr, aliphatic carboxylic acid ligand: terephthalic acid) Zirconium tetrachloride (ZrCl ₄ ) 8.35 mmol, 8.35 mmol of terephthalic acid (TPA), and 30 mL of DMF were sequentially measured in a beaker and stirred for 10 minutes. The obtained mixture was put in a 50 mL stainless steel autoclave whose inner surface was Teflon-processed, and then replaced with nitrogen four times to make the inside a nitrogen atmosphere at atmospheric pressure. Thereafter, the temperature was raised from room temperature to 180 ° C. over 1 hour, kept at 180 ° C. for 12 hours, and then allowed to cool to room temperature. During the synthesis, the liquid was stirred with a stirrer at 200 rpm. The solid was centrifuged at 5000 rpm for 10 minutes. Subsequently, ultrasonic cleaning (28 kHz, 10 minutes) and centrifugation were performed with acetone, methanol, and pure water, respectively, and the product was recovered. Then, it dried at 80 degreeC overnight, and also dried under reduced pressure at 200 degreeC for 2 hours, and obtained the target object.
Specific surface area: 740 m ² / g
Average pore diameter: 0.6 nm

Comparative Example 2: UiO-67 (metal: Zr, aliphatic carboxylic acid ligands: 4,4'-biphenyl dicarboxylic acid) Preparation of zirconium tetrachloride (ZrCl ₄₎ 1.40 mmol, 4,4'-biphenyl dicarboxylic acid 1.40 mmol and DMF 20 mL were sequentially measured in a beaker and stirred for 10 minutes. The obtained mixture was put in a 50 mL stainless steel autoclave whose inner surface was Teflon-processed, and then replaced with nitrogen four times to make the inside a nitrogen atmosphere at atmospheric pressure. Thereafter, the temperature was raised from room temperature to 120 ° C. over 1 hour, kept at 120 ° C. for 24 hours, and then allowed to cool to room temperature. During the synthesis, the liquid was stirred with a stirrer at 200 rpm. The solid was centrifuged at 5000 rpm for 10 minutes. Subsequently, ultrasonic cleaning (28 kHz, 10 minutes) and centrifugation were performed with acetone, methanol, and pure water, respectively, and the product was recovered. Then, it dried at 80 degreeC overnight, and also dried under reduced pressure at 200 degreeC for 2 hours, and obtained the target object.
Specific surface area: 1530 m ² / g
Average pore diameter: 0.6 nm

Comparative Example 3: Preparation of MOF-808 (metal: Zr, aliphatic carboxylic acid ligand: trimesic acid) Zirconium oxychloride (ZrCl ₂ O · 8H ₂ O) 2.60 mmol, trimesic acid 2.60 mmol, DMF 20 mL, formic acid Formic acid 10 mL were measured in this order in a beaker and stirred for 10 minutes. The obtained mixture was put in a 50 mL stainless steel autoclave whose inner surface was Teflon-processed, and then replaced with nitrogen four times to make the inside a nitrogen atmosphere at atmospheric pressure. Thereafter, the temperature was raised from room temperature to 120 ° C. over 1 hour, kept at 120 ° C. for 24 hours, and then allowed to cool to room temperature. No agitation was performed during the synthesis. The solid was centrifuged at 5000 rpm for 10 minutes. Subsequently, ultrasonic cleaning (28 kHz, 10 minutes) and centrifugation were performed with acetone, methanol, and pure water, respectively, and the product was recovered. Then, it dried at 80 degreeC overnight, and also dried under reduced pressure at 200 degreeC for 2 hours, and obtained the target object.
Specific surface area: 1430 m ² / g
Average pore diameter: 0.7 nm
<Alternative method>
In addition, a product having almost the same pattern in both the XRD pattern and the adsorption / desorption isotherm can be obtained even if it is prepared using the same method as in Comparative Example 3 except that ZrCl ₂ O · 8H ₂ O is replaced with ZrCl _4. I was able to.

Comparative Example 4: MOF-Al-F (metal: Al, aliphatic carboxylic acid ligands: Fumaric acid) Preparation of aluminum nitrate Al (NO ₃₎ of _{3 · 9H 2 O 7.42 mmol,} TPA 12.6 mmol, DMF 17.2 mL, Acetic acid 12.8 mL was placed in a beaker in order and stirred for 10 minutes. The obtained mixture was put in a 50 mL stainless steel autoclave whose inner surface was Teflon-processed, and then replaced with nitrogen four times to make the inside a nitrogen atmosphere at atmospheric pressure. Thereafter, the temperature was raised from room temperature to 130 ° C. over 1 hour, kept at 130 ° C. for 17 hours, and then allowed to cool to room temperature. During the synthesis, the liquid was stirred with a stirrer at 200 rpm. The solid was centrifuged at 5000 rpm for 10 minutes. Subsequently, ultrasonic cleaning (28 kHz, 10 minutes) and centrifugation were performed with acetone, methanol, and pure water, respectively, and the product was recovered. Then, it dried at 80 degreeC overnight, and also dried under reduced pressure at 200 degreeC for 2 hours, and obtained the target object.
Specific surface area: 1440 m ² / g
Average pore diameter: 0.6 nm

Comparative Example 5: Preparation of MIL-88A (metal: Fe, aliphatic carboxylic acid ligand: fumaric acid) Iron chloride (III) FeCl ₃ · 6H ₂ O 10.0 mmol, fumaric acid 10.0 mmol, DMF 50 mL It measured in order in the beaker and stirred for 10 minutes. Half of the obtained mixture was put in a 50 mL stainless steel autoclave whose inner surface was Teflon-treated, and then replaced with nitrogen four times to make the inside a nitrogen atmosphere at atmospheric pressure. Thereafter, the temperature was raised from room temperature to 100 ° C. in 30 minutes, kept at 100 ° C. for 12 hours, and then allowed to cool to room temperature. During the synthesis, the mixture was stirred with a stirrer at 200 rpm. The solid was filtered off with suction. Next, the product was recovered by washing with pure water and acetone. Then, it dried at 80 degreeC overnight, and also dried under reduced pressure at 120 degreeC for 2 hours, and obtained the target object.
Specific surface area: 170 m ² / g
Average pore diameter: 0.6 nm

Comparative Example 6: MIL-101 (metal: Cr, aliphatic carboxylic acid ligand: terephthalic acid) prepared chromium nitrate Cr (NO ₃₎ of ₃ · 9H ₂ O 8.35 mmol, terephthalic acid Terephthalic acid (hereinafter, TPA) 12.6 mmol and 30 mL of pure water were sequentially measured in a beaker and stirred for 10 minutes. The obtained mixture was put in a 50 mL stainless steel autoclave whose inner surface was Teflon-processed, and then replaced with nitrogen four times to make the inside a nitrogen atmosphere at atmospheric pressure. Thereafter, the temperature was raised from room temperature to 180 ° C. over 1 hour, kept at 180 ° C. for 12 hours, and then allowed to cool to room temperature. During the synthesis, the liquid was stirred with a stirrer at 200 rpm. The solid was centrifuged at 5000 rpm for 10 minutes. Subsequently, ultrasonic cleaning (28 kHz, 10 minutes) was performed with DMF, followed by centrifugation. Further, in order to remove DMF, ultrasonic washing with acetone and centrifugation (5000 rpm, 5 minutes) were performed, followed by drying at 80 ° C. overnight, and then drying under reduced pressure at 200 ° C. for 2 hours to obtain the desired product.
Specific surface area: 2730 m ² / g
Average pore diameter: 0.9nm

Comparative Example 7: MOF-Al-T (metal: Al, aliphatic carboxylic acid ligand: terephthalic acid) Preparation of Preparation of aluminum nitrate _{Al (NO 3) 3 · 9H} 2 O 8.75 mmol, TPA 8.75 mmol, purified water 30 mL was put into a beaker in order and stirred for 10 minutes. The obtained mixture was put in a 50 mL stainless steel autoclave whose inner surface was Teflon-processed, and then replaced with nitrogen four times to make the inside a nitrogen atmosphere at atmospheric pressure. Thereafter, the temperature was raised from room temperature to 180 ° C. over 1 hour, kept at 180 ° C. for 12 hours, and then allowed to cool to room temperature. During the synthesis, the liquid was stirred with a stirrer at 200 rpm. The solid was centrifuged at 5000 rpm for 10 minutes. Subsequently, ultrasonic cleaning (28 kHz, 10 minutes) was performed with DMF, followed by centrifugation. Furthermore, in order to remove DMF, ultrasonic cleaning with acetone and centrifugation (5000 rpm, 5 minutes) were performed, followed by drying at 80 ° C. overnight. Finally, the target product was obtained by heat treatment at 330 ° C. for 72 hours in a nitrogen atmosphere.
Specific surface area: 1280 m ² / g
Average pore diameter: 0.6 nm

Test example 1
The metal organic structure 0.025 g or 0.050 g obtained in Example 1 and Comparative Examples 1 to 7 was put in a column (inner diameter 3 mm × length 10 cm), and both ends were fixed with glass wool. The filling length of the metal organic structure was about 12 mm to about 20 mm because the bulk density of the metal organic structure was different. This was set in the column tank of gas chromatography (Shimadzu Corporation GC-8A). Carrier gas was supplied at a flow rate of 15 mL / min. The column bath temperature was 170 ° C., and p-xylene, m-xylene, and o-xylene were each injected into the column from the gas chromatography inlet maintained at 0.2 ° C. or 1.0 μL at 220 ° C. The response at the column outlet was detected with a thermal conductivity detector (220 ° C.). Table 1 shows the time at the peak of each peak, which is an index of separability.

  For the metal organic structures of Example 1 and Comparative Example 1, 0.4 μL of a xylene mixture of p-xylene (33.3 mol%), m-xylene (33.3 mol%), and o-xylene (33.4 mol%) was added to the column temperature. The results of injection at 170 ° C. are shown in FIGS. 9 and 10, respectively.

<Result>
The metal organic structure of Example 1 was found to be separated into a mixed peak of m-xylene (0.23 minutes) and o-xylene (0.20 minutes) and a peak of p-xylene (1.94 minutes).

  Using this metal organic structure of Example 1, exhaust gas corresponding to the peak of the p-xylene portion when 1.0 μL of the xylene mixture of Test Example 1 was injected was collected, and a gas chromatography having a hydrogen detector ( As a result of analysis by Shimadzu Corporation GC-2014), when p-xylene is converted to 100, the ratio is m-xylene 12.4 and o-xylene 1.3, and high-purity p-xylene can be produced. I understood.

  As described above, the metal organic structure obtained in Example 1 was able to selectively separate paraxylene.

  On the other hand, the metal organic structures obtained in Comparative Examples 1 to 7 could not selectively separate paraxylene.

Claims (18)

A method for separating para-xylene from an organic mixture containing para-xylene, comprising:
A method using a metal organic structure comprising a Group 4 metal and an aliphatic carboxylic acid ligand. The method according to claim 1, wherein the organic mixture containing para-xylene is an organic mixture containing an aromatic hydrocarbon having 8 carbon atoms. The method according to claim 1, wherein the Group 4 metal is at least one selected from the group consisting of Ti, Zr, and Hf. 4. The aliphatic carboxylic acid ligand according to any one of claims 1 to 3, wherein the aliphatic carboxylic acid ligand is an aliphatic dicarboxylic acid ligand, an aliphatic tricarboxylic acid ligand, or an aliphatic tetracarboxylic acid ligand. Method. The aliphatic carboxylic acid ligand is
A saturated or unsaturated aliphatic dicarboxylic acid ligand having 2 to 7 carbon atoms,
The saturated or unsaturated aliphatic tricarboxylic acid ligand having 3 to 8 carbon atoms, or the saturated or unsaturated aliphatic tetracarboxylic acid ligand having 5 to 8 carbon atoms. The method described in 1. The method according to claim 1, wherein the aliphatic carboxylic acid ligand is a fumaric acid ligand or a maleic acid ligand. A method for producing high purity para-xylene, comprising:
The manufacturing method including the process of isolate | separating paraxylene using the organic mixture containing a paraxylene, and the metal organic structure containing a group 4 metal and an aliphatic carboxylic acid ligand. The method according to claim 7, wherein the organic mixture containing para-xylene is an organic mixture containing an aromatic hydrocarbon having 8 carbon atoms. The method according to claim 7 or 8, wherein the Group 4 metal is at least one selected from the group consisting of Ti, Zr, and Hf. 10. The aliphatic carboxylic acid ligand according to claim 7, wherein the aliphatic carboxylic acid ligand is an aliphatic dicarboxylic acid ligand, an aliphatic tricarboxylic acid ligand, or an aliphatic tetracarboxylic acid ligand. Method. The aliphatic carboxylic acid ligand is
A saturated or unsaturated aliphatic dicarboxylic acid ligand having 2 to 7 carbon atoms,
The saturated or unsaturated aliphatic tricarboxylic acid ligand having 3 to 8 carbon atoms or the saturated or unsaturated aliphatic tetracarboxylic acid ligand having 5 to 8 carbon atoms. The method described in 1. The method according to any one of claims 7 to 11, wherein the aliphatic carboxylic acid ligand is a fumaric acid ligand or a maleic acid ligand. A metal organic structure for separation of para-xylene, comprising a Group 4 metal and an aliphatic carboxylic acid ligand. The metal organic structure for paraxylene separation according to claim 13, for separating paraxylene from a mixture containing an aromatic hydrocarbon having 8 carbon atoms. The metal-organic structure for paraxylene separation according to claim 13 or 14, wherein the Group 4 metal is at least one selected from the group of metals consisting of Ti, Zr, and Hf. 16. The aliphatic carboxylic acid ligand according to any one of claims 13 to 15, wherein the aliphatic carboxylic acid ligand is an aliphatic dicarboxylic acid ligand, an aliphatic tricarboxylic acid ligand, or an aliphatic tetracarboxylic acid ligand. Metal organic structure for separation of para-xylene. The aliphatic carboxylic acid ligand is
A saturated or unsaturated aliphatic dicarboxylic acid ligand having 2 to 7 carbon atoms,
The saturated or unsaturated aliphatic tricarboxylic acid ligand having 3 to 8 carbon atoms, or the saturated or unsaturated aliphatic tetracarboxylic acid ligand having 5 to 8 carbon atoms. Metal organic structure for separation of para-xylene as described in 1. The metal organic structure for paraxylene separation according to any one of claims 13 to 17, wherein the aliphatic carboxylic acid ligand is a fumaric acid ligand or a maleic acid ligand.