CN110776522B - A kind of copper metal organic framework material and preparation method thereof, gas capture method, gas separation method - Google Patents

Abstract

The present invention provides a copper metal organic framework material, the molecular formula of which is {[Cu ₂ (P)·(H ₂ O) ₂ ]·2H ₂ O·3DMF·(CH ₃ ) ₂ NH ₂ ]} _n , where P is a negative pentavalent anion ligand, the metal organic framework material belongs to the trigonal crystal system, the space group is R-3m, has a (4, 4)-connected NbO configuration topology, and the unit cell parameter is

α/deg=90.0, β/deg=90.0, γ/deg=120.0,

The invention uses the copper metal organic framework material as the adsorbent, the metal organic framework material has good stability, can capture carbon dioxide and selectively adsorb the mixed gas of carbon dioxide and methane, and has high adsorption selectivity.

Description

A kind of copper metal organic framework material and its preparation method, gas capture method, gas separation method

technical field

The invention relates to the field of materials, in particular to a copper metal organic framework material, a preparation method for a copper metal organic framework material, a _CO2 gas capture method, and a _CO2 gas and _CH4 gas separation method.

Background technique

With the development of the global economy and technology, human demand for fossil fuels, oil, coal, etc. continues to increase, and fossil fuels will still occupy a dominant position at present and for a period of time in the future. Combustion leads to a large amount of _CO2 emissions, which causes serious pollution to the environment. CO ₂ is an important part of greenhouse gas, and many environmental problems caused by its massive emission will also lead to the destruction of the earth's ecology to a great extent. Therefore, how to effectively remove _CO2 from industrial mixed gas has been the focus of both scientific and industrial circles in recent years.

On the one hand, adopting a low-consumption and high-efficiency method for _CO adsorption will be the key to alleviating environmental and economic conflicts. On the other hand, natural gas has the advantages of high calorific value, abundant resources and environmental friendliness, and is considered as a good alternative energy. The main component of natural gas is methane, but in the process of exploitation and transportation of natural gas, other impurities such as CO ₂ are often mixed with the main components. If CO ₂ cannot be effectively removed, it will affect the quality of natural gas and reduce the calorific value. At the same time, it will cause pipeline corrosion and cause safety hazards. Effective adsorption and separation of _CO2 and _CH4 gas can not only alleviate environmental pollution, but also improve the quality of natural gas. Therefore, the adsorption separation of _CO2 is of great environmental and industrial significance. The traditional porous adsorption materials such as zeolite, molecular sieve, and carbon materials have low adsorption capacity and poor selectivity for _CO2 .

In recent years, metal-organic frameworks (MOFs) have become the most rapidly developing new porous materials in the field of materials due to their high specific surface area, tunable pore structure and pore surface chemical properties. Compared with traditional materials, MOFs materials exhibit excellent properties such as good selectivity, large adsorption capacity, and strong stability, and show great potential in the field of gas adsorption and separation. For example, metal-organic framework materials can be constructed by adjusting the size of ligands to construct materials with large specific surface area to enhance the adsorption capacity; constructing MOF materials with suitable pore size, the dynamic radii of different gas molecules can be used to achieve different molecular interactions. separation. Through functional modification, the chemical environment of the pore surface is changed and unsaturated sites are generated, so that the force of the pore surface on the gas molecules is different, and the recognition ability of the skeleton to the gas is improved.

At present, there are few technical solutions for the adsorption and separation of gas molecules using metal organic framework materials, which have both high CO ₂ adsorption capacity and CO ₂ /CH ₄ separation.

SUMMARY OF THE INVENTION

In order to solve the problems in the prior art, the present invention proposes a copper metal organic framework material and a preparation method thereof, a gas capture method and a gas separation method. The prepared metal organic framework material can be effectively used in the efficient adsorption of CO ₂ . Selective adsorption with _CO2 / _CH4 .

The technical scheme of the present invention is realized as follows:

According to a first aspect of the present invention, a copper metal organic framework material is proposed.

In some optional embodiments, the above-mentioned copper metal organic framework material, its chemical formula is {[Cu ₂ (P)·(H ₂ O) ₂ ]·2H ₂ O·3DMF·(CH ₃ ) ₂ NH ₂ ]} _n , where P is a negative pentavalent anion ligand, and the structural formula of H ₅ P is:

α/deg＝90.0，β/deg＝90.0，γ/deg＝120.0，

Optionally, the metal organic framework material belongs to the trigonal crystal system, the space group is R-3m, has a (4,4)-connected NbO configuration topology, and the unit cell parameter is

α/deg=90.0, β/deg=90.0, γ/deg=120.0,

更大的梭型笼是由十二个无机SBUs和六个有机配体构成的，孔道直径为

两者之间为三角形窗口相互连接；球状笼和梭型笼以1:1的比例交替连接形成3D周期性网状结构。Alternatively, each Cu ²⁺ ion adopts a five-coordination mode to coordinate with the oxygen of four carboxylic acids and the oxygen of one water molecule, presenting a quadrangular pyramid, with two adjacent Cu ²⁺ centers passing through the four carboxylic acids. The base is bridged to form a paddle wheel-shaped secondary building unit Cu ₂ (COO) ₄ (H ₂ O) ₂ , and a 3D periodic network structure is constructed through ligand bridges; along the c-axis direction, the 3D periodic network There are two types of pore cages in the 1:1 pore structure: the small spherical cage is composed of six inorganic SBUs and six organic ligands, and the pore diameter is

The larger shuttle cage is composed of twelve inorganic SBUs and six organic ligands with a pore diameter of

The two are connected by triangular windows; spherical cages and shuttle-shaped cages are alternately connected at a ratio of 1:1 to form a 3D periodic network structure.

According to the second aspect of the present invention, a preparation method of a copper metal organic framework material is proposed.

In some optional embodiments, the preparation method of the above-mentioned copper metal organic framework material includes the following steps:

1.8-2.1 parts by weight of solid Cu(NO ₃ ) ₂ ·3H ₂ O and 2.7-3.0 parts by weight of white powder H ₅ P were added to a glass bottle, H ₅ P=4-((3,5-dicarboxyphenyl)ethynyl) -[1,1'-biphenyl]-2,3',5'-tricarboxylic acid;

A mixed solution of 290-310 parts by weight of DMF/H ₂ O was added to the glass bottle, the volume ratio of DMF/H ₂ O was 6:1, and 2.8-3.1 parts by weight of concentrated hydrochloric acid solution ( 37.5%), the mixed solution was sealed and put into a blast drying oven, heated from room temperature to 85-90 °C;

Keep at 85～90℃ for 2500min～3500min;

Then, the mixture is cooled to 25-35°C at a rate of 5-8°C per hour to obtain blue bulk crystals;

Filtering the above blue crystals is copper metal organic framework material, its molecular formula is {[Cu ₂ (P)·(H ₂ O) ₂ ]·2H ₂ O·3DMF·(CH ₃ ) ₂ NH ₂ ]} _n , the formula Among them, P is a negative pentavalent anion ligand, and the structural formula of H ₅ P is:

Optionally, the mixed solution is sealed and placed in a blast drying oven, heated from room temperature to 87°C.

Optionally, the mixed solution is sealed and put into a blast drying oven, heated from room temperature to 85-90° C., and kept at 85-90° C. for 3000 min.

Optionally, the mixture was cooled to 25-35°C at a rate of 7°C per hour to obtain blue bulk crystals.

Alternatively, the mixture was cooled to 30°C at a rate of 7°C per hour to obtain blue bulk crystals.

According to a third aspect of the present invention, a _CO2 gas capture method is proposed.

In some optional embodiments, the above-mentioned CO ₂ gas capture method adopts the copper metal organic framework material described in any of the above-mentioned optional embodiments to adsorb CO ₂ gas.

According to a fourth aspect of the present invention, a _CO2 gas and _CH4 gas separation method is proposed.

In some optional embodiments, the above-mentioned CO ₂ gas and CH ₄ gas separation method adopts the copper metal organic framework material described in any of the above-mentioned optional embodiments to adsorb CO ₂ gas.

The beneficial effects of the present invention are:

(1) Using copper metal organic framework material as adsorbent, metal organic framework material has good stability, and can capture carbon dioxide and selectively adsorb mixed gas of carbon dioxide and methane, with high adsorption selectivity;

(2) The pentacarboxylic acid ligand is used, and the ligand on the intermediate benzene ring does not participate in the coordination and deprotonation, forming an anionic framework; the uncoordinated carboxylic acid in the pore channel is a strong polar functional group, which can enhance the The polarizability of _CO2 , thereby increasing the interaction between the framework and _CO2 , which is beneficial to the adsorption and separation of _CO2 ;

(3) The functional modification of acetylenic bonds and unsaturated copper sites on the pore surface of copper metal organic framework materials enhances its electrostatic interaction with _CO ;

(4) The synthesis method is simple and easy to operate, has strong operability, low reaction temperature and high process safety, and has wide application in solving the greenhouse effect and industrial purification of natural gas.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained according to these drawings without creative efforts.

Figure 1 is a diagram of the ligands used in the blue bulk crystal and the coordination environment of Cu ²⁺ ions.

Figure 2 is a schematic diagram of the spherical and fusiform cage structures of the blue bulk crystal along the a-axis.

Figure 3 is a schematic diagram of the three-dimensional frame stacking of blue bulk crystals along the c-axis.

FIG. 4 is a graph of the thermogravimetric loss of the initial synthesized sample of copper metal organic framework material.

Figure 5 is the powder X-ray diffraction pattern of the initial synthesized sample and the activated sample of the copper metal organic framework material.

Figure ₆ is a schematic diagram of the N adsorption isotherm of copper metal organic frameworks at 77 K.

Figure 7a is a schematic diagram of _CO adsorption isotherms for copper metal organic frameworks at 273K and 295K.

Figure 7b is a schematic diagram of the CH adsorption isotherms of Cu metal organic frameworks at 273K and _295K .

Figure 8 is the selective adsorption curve of _CO2 for _CH4 of copper metal organic framework materials.

Detailed ways

In order for those with ordinary knowledge in the art to understand the features and effects of the present invention, general descriptions and definitions of terms and terms mentioned in the specification and the scope of the patent application are provided below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meanings understood by those skilled in the art to the present invention, and in case of conflict, the definitions in this specification shall prevail.

As used herein, the terms "comprising", "including", "having", "containing" or any other similar terms are open-ended transitional phrases intended to cover non-exclusive inclusions. For example, a composition or article of manufacture containing a plurality of elements is not limited to only those elements listed herein, but can also include other elements not expressly listed, but which are generally inherent to the composition or article of manufacture. Otherwise, unless expressly stated to the contrary, the term "or" refers to an inclusive "or" rather than an exclusive "or". For example, the condition "A or B" is satisfied by any of the following: A is true (or present) and B is false (or absent), A is false (or absent) and B is true (or present), Both A and B are true (or exist). In addition, in this document, the terms "comprising", "including", "having", "containing" should be interpreted as having specifically disclosed and encompassing both "consisting of" and "substantially consisting of" and other closures Formal or semi-closed connectives.

In this document, all features or conditions defined as numerical ranges or percentage ranges are for brevity and convenience only. Accordingly, the description of numerical ranges or percentage ranges should be considered to encompass and specifically disclose all possible sub-ranges and individual numerical values within the range, particularly integer numerical values. For example, a range description of "1 to 8" should be deemed to have specifically disclosed all subranges such as 1 to 7, 2 to 8, 2 to 6, 3 to 6, 4 to 8, 3 to 8, etc., particularly are sub-ranges bounded by all integer values, and should be deemed to have specifically disclosed individual values within the range such as 1, 2, 3, 4, 5, 6, 7, 8, etc. Unless otherwise indicated, the foregoing method of interpretation applies to all matters throughout this disclosure, whether broad or not.

If a quantity or other value or parameter is expressed as a range, a preferred range, or a series of upper and lower limits, it should be understood that any upper or preferred value of the range and the lower limit of the range have been specifically disclosed herein or all ranges of preferred values, whether or not those ranges are disclosed separately. Furthermore, when a range of values is referred to herein, unless otherwise indicated, the range shall include its endpoints and all integers and fractions within the range.

As used herein, numerical values should be understood to have an accuracy of significant digits of the numerical value, provided that the purpose of the invention can be achieved. For example, the number 40.0 should be understood to cover the range from 39.50 to 40.49.

Where Markush group or alternative terminology is used herein to describe features or examples of the invention, those skilled in the art will understand the Markush group or subgroups of all elements within a list of options Groups or any individual element may also be used to describe the invention. For example, if X is described as "selected from the group consisting of X ₁ , X ₂ and X ₃ ", it also means that the claim that X is X ₁ and that X is X ₁ and/or X ₂ have been fully described claim. Furthermore, where Markush group or option terminology is used to describe features or instances of the invention, those skilled in the art will recognize subgroups or individual elements of all elements within the Markush group or option list Any combination of , can also be used to describe the invention. Accordingly, for example, if X is described as "selected from the group consisting of X ₁ , X ₂ and X ₃ " and Y is described as "selected from the group consisting of Y ₁ , Y ₂ and Y ₃ group of "," means that the claim that X is X ₁ or X ₂ or X ₃ and Y is Y ₁ or Y ₂ or Y ₃ has been fully described.

The following detailed description is merely exemplary in nature and is not intended to limit the invention and its uses. Furthermore, there is no intention to be bound by any theory presented in the preceding prior art or this summary or in the following detailed description or examples.

Elemental Analysis Results

Elemental analysis is performed on the material obtained by the above-mentioned preparation method of the copper metal organic framework material of the present invention.

Elemental Analysis Results

The contents of C, N and O are determined according to elemental analysis and single crystal diffraction data, and then the chemical formula of the metal-organic framework material is determined to be C ₃₆ Cu ₂ O ₁₇ H ₄₆ N ₄ .

Structural description of copper metal organic frameworks

更大一些的梭型笼是由十二个无机SBUs和六个有机配体构成的，孔道直径大约为

两者之间为三角形窗口相互连接。上述两种孔笼以1:1的比例交替连接形成3D周期性网状结构。As shown in Figure 1, Figure 2 and Figure 3, based on elemental analysis, TGA and single crystal X-ray diffraction, the molecular formula of the copper metal organic framework material is {[Cu ₂ (P)·(H ₂ O) ₂ ]·2H ₂ O·3DMF·(CH ₃ ) ₂ NH ₂ ]} _n . The copper metal organic framework material belongs to the trigonal crystal system, the space group is R-3m, and has a (4,4)-connected NbO configuration topology, which has the same spatial structure as NOTT-101 and ZJU-24, except Replace all link chains with P. Each Cu ²⁺ ion adopts a five-coordination mode to coordinate with the oxygen of four carboxylic acids and the oxygen of one water molecule, showing a quadrangular pyramid, and the adjacent two Cu ²⁺ centers are bridged by four carboxylic acid groups, A paddle-wheel-shaped secondary building block Cu ₂ (COO) ₄ (H ₂ O) ₂ is formed, and a 3D periodic network structure is further constructed by ligand bridging. Along the c-axis, there are two 1:1 "pore-cage" types of pore structures in the above-mentioned 3D periodic network structure: the small spherical cage is composed of six inorganic SBUs (secondary structural units) and six organic composed of ligands, the pore diameter is approximately

The larger shuttle cages are composed of twelve inorganic SBUs and six organic ligands, with pore diameters of approximately

The two are connected with each other by triangular windows. The above two kinds of pore cages are alternately connected in a 1:1 ratio to form a 3D periodic network structure.

Thermal Stability Analysis of Copper Metal Organic Frameworks

Figure 4 shows the thermogravimetric curve of the copper metal organic framework material. It can be seen from the figure that in the temperature variation range of 0–800 °C, the thermogravimetric curve shows three obvious declines; in the first stage, it is 100 Before ℃, the corresponding free water molecules in the pores of the copper metal organic framework material are lost; in the second stage, from 100 to 285 ℃, the solvent molecules DMF (N,N-dimethylformamide) and coordination water molecules are mainly lost. Above 310°C, the crystal framework begins to collapse.

Powder Diffraction Testing of Copper Metal Organic Frameworks

Powder diffraction testing (PXRD) was used to detect the phase purity of copper metal organic framework material samples at room temperature. As shown in Figure 5, the diffraction pattern (As-synthesized) of the crystal sample synthesized by the experiment is consistent with the diffraction pattern (Simulated) derived from the single crystal data cif file, indicating that the copper metal organic framework material of the crystal sample has been successfully prepared and has a relatively high quality. High phase purity. The diffraction peaks of activated copper metal organic frameworks (Activatecd) and the diffraction peaks of experimentally synthesized samples (As-synthesized) are basically the same, indicating that the activated copper metal organic frameworks have stable frameworks.

Study on the performance of gas adsorption and separation

In order to prove that the gold _- copper metal organic framework material has permanent pores, its N adsorption amount at 77K was tested. The specific test process is as follows: first, the sample is activated by the solvent exchange method, soaked in dichloromethane for 1 day and then in chromatographic methanol for 3 days. During the period, fresh methanol solution is replaced every 12 hours to replace DMF and water that are not involved in the coordination. Molecules were then activated under vacuum at 95°C for 10 hours. The desolvated copper metal organic framework material was obtained, and the color of the sample changed from blue to dark blue, indicating that the coordination water of the copper metal organic framework material had been removed after activation.

The adsorption isotherm of _N2 at 77K was tested, as shown in Fig. 6, the _N2 adsorption curve of the activated copper metal-organic framework material is a typical type-I adsorption isotherm. This indicates that the copper metal organic framework material has a continuous microporous structure, and the original pore structure is retained after the solvent molecules are removed. The adsorption capacity of the adsorption curve in the low pressure region (P/P ⁰ <0.01) increased sharply, which means that the micropores of the copper metal organic framework material exist and are filled in an orderly manner. After that, the nitrogen adsorption capacity was saturated at about 0.1 bar, and the N ₂ adsorption capacity of the copper metal organic framework material reached 656 cm ³ (STP)·g ^-1 under the condition of 77K and 1 bar. The BET surface area of copper metal organic framework material is 2560m ² ·g ^-1 , which is larger than that of ZJU-24-0.5 (1700m ² ·g ^-1 ), but larger than that of structure NOTT-101 (2800m ² ·g ^-1 ) Small. The reason is that the uncoordinated carboxyl group extends into the channel, and the counter ion dimethylamine (dimethylamine is the decomposition product of DMF at high temperature, it is the protest ion of the skeleton, and it is a cationic compound) is also in the channel. , making the pore volume of copper metal organic framework materials smaller. Copper metal-organic frameworks have large specific surface areas, carboxyl- and acetylenic bond-functionalized pore surfaces, and stable pore structures. In Fig. 7a and Fig. 7b, the _CO and CH adsorption properties of copper metal _- organic framework materials were further determined. It can be seen from Fig. 7a that under the condition of 1 bar and 273K, the adsorption amount of CO ₂ reaches 161cm ³ (STP)·g ^-1 , which is higher than that of CPF-1 (83.5cm ³ (STP)·g ^-1 ) and NTU-101-Cu (101cm ³ (STP)·g ^-1 ), but lower than some MOFs with strong CO ₂ adsorption properties, such as NOTT-101 (164cm ³ (STP)·g ^-1 ). It can be seen from Figure 7b that under the condition of 273K and 1bar, the adsorption amount of _CH4 is only 28.5cm ³ (STP)·g ^-1 , and under the condition of 295K and 1bar, the adsorption amount of CH ₄ is 17.2cm ³ ( STP)·g ⁻¹ .

As shown in Fig. 8, it can be seen that the adsorption selectivity of copper metal organic framework material in CO ₂ /CH ₄ (50:50) mixed gas is 12.6 under the condition of 273K, and the high selectivity indicates that the carboxylic acid group is used in the pores. The group modification can enhance the affinity of the framework for _CO2 , and the formation of hydrogen bond interactions can significantly improve its separation performance. On the other hand, _CO2 has a four-dipole moment and strong electrostatic interaction with the framework. With the increase of _CO adsorption, _CO molecules occupy more adsorption sites, resulting in a relative decrease in the amount of CH adsorption _. The selective adsorption of CO ₂ by copper metal organic framework materials indicates that copper metal organic framework materials have the potential to purify natural gas.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the scope of the present invention. within the scope of protection.

Claims (10)

1. A copper metal organic frame material is characterized in that the molecular formula is { [ Cu ] ₂ (P)·(H ₂ O) ₂ ]·2H ₂ O·3DMF·(CH ₃ ) ₂ NH ₂ ]} _n Wherein P is a negative pentavalent anionic ligand, H ₅ The structural formula of P is:

2. the copper metal-organic framework material according to claim 1, wherein the metal-organic framework material belongs to the trigonal system, has a space group of R-3m, has a (4, 4) -connected NbO topology, and has a unit cell parameter of

α/deg＝90.0，β/deg＝90.0，γ/deg＝120.0，

3. The copper metal-organic framework material according to claim 1,

each of Cu ²⁺ The ion adopts a penta-coordination mode to coordinate with oxygen of four carboxylic acids and oxygen of one water molecule, and presents a quadrangular pyramid shape, and two adjacent Cu ²⁺ The center is bridged by four carboxylic acid groups to form a paddle-wheel-shaped secondary construction unit Cu ₂ (COO) ₄ (H ₂ O) ₂ Constructing a 3D periodic network structure through ligand bridging; along the c-axis direction, there is 1:1, two types of pore cage: the small spherical cage is composed of six inorganic SBUs and six organic ligands, and the diameter of the pore channel is

The larger shuttle cage is composed of twelve inorganic SBUs and six organic ligands, and the diameter of the pore channel is

The two are connected with each other through a triangular window; the spherical cages and the shuttle-shaped cages are alternately connected in a ratio of 1:1 to form a 3D periodic reticular structure.

4. A preparation method of a copper metal organic framework material is characterized by comprising the following steps:

1.8 to 2.1 parts by weight of solid Cu(NO ₃ ) ₂ ·3H ₂ O and 2.7-3.0 parts by weight of white powder H ₅ Adding P into a glass bottle;

290-310 parts by weight of DMF/H is added into a glass bottle ₂ Mixed solution of O, DMF/H ₂ The volume ratio of O is 6: 1, dropwise adding 2.8-3.1 parts by weight of concentrated hydrochloric acid solution into the mixed solution, sealing the mixed solution, putting the sealed mixed solution into a forced air drying oven, and heating the mixed solution to 85-90 ℃ from room temperature;

keeping the temperature for 2500-3500 min at 85-90 ℃;

then, cooling the mixture to 25-35 ℃ at the rate of 5-8 ℃ per hour to obtain a blue blocky crystal;

filtering the blue crystal to obtain copper metal organic frame material with molecular formula { [ Cu { [ ₂ (P)·(H ₂ O) ₂ ]·2H ₂ O·3DMF·(CH ₃ ) ₂ NH ₂ ]} _n Wherein P is a negative pentavalent anionic ligand, H ₅ The structural formula of P is:

5. the method according to claim 4, wherein the organic framework material of copper is selected from the group consisting of,

the mixed solution was sealed and placed in an air-blown dry box and heated from room temperature to 87 ℃.

6. The method according to claim 4, wherein the organic framework material of copper is selected from the group consisting of,

and sealing the mixed solution, putting the sealed solution into a blast drying oven, heating the solution to 85-90 ℃ from room temperature, and keeping the temperature at 85-90 ℃ for 3000 min.

7. The method according to claim 4, wherein the organic framework material of copper is selected from the group consisting of,

and cooling the mixture to 25-35 ℃ at the rate of 7 ℃ per hour to obtain blue blocky crystals.

8. The method according to claim 7, wherein the organic framework material of copper is selected from the group consisting of,

the mixture was cooled to 30 ℃ at a rate of 7 ℃ per hour to give blue blocky crystals.

9. CO (carbon monoxide) ₂ A gas capture process, characterized in that the copper metal organic framework material according to any of claims 1 to 3 is used for CO ₂ The gas is adsorbed.

10. CO (carbon monoxide) ₂ Gas and CH ₄ Gas separation process, characterized in that the copper metal organic framework material according to any of claims 1 to 3 is used for CO ₂ The gas is adsorbed.

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