CN110437464B

CN110437464B - Linear imidazole ligand strong electronegativity copper complex and preparation method thereof

Info

Publication number: CN110437464B
Application number: CN201910774279.1A
Authority: CN
Inventors: 刘双; 刘澜涛; 周艳丽; 张付力; ***
Original assignee: Shangqiu Normal University
Current assignee: Shangqiu Normal University
Priority date: 2019-08-21
Filing date: 2019-08-21
Publication date: 2021-05-28
Anticipated expiration: 2039-08-21
Also published as: CN110437464A

Abstract

The invention discloses a linear imidazole ligand strong electronegativity copper complex and a preparation method thereof, belonging to the technical field of polymer self-assembly and supramolecular materials. The chemical formula is [ Cu (L)₂SiF₆]Wherein L is a 1, 4-diimidazolyl benzene ligand. The preparation method has the advantages of simple preparation process, low cost, mild conditions and strong electronegativity in the three-dimensional structure₆The catalyst has good adsorption performance on acetylene, has good selectivity, can well remove trace acetylene in ethylene, and meets the requirement of industrial ethylene polymerization reaction on ethylene purity.

Description

Linear imidazole ligand strong electronegativity copper complex and preparation method thereof

Technical Field

The invention belongs to the technical field of high polymer chemistry, polymer self-assembly and supramolecular materials, and particularly relates to a linear imidazole ligand strong electronegativity copper complex and a preparation method thereof.

Background

Ethylene is one of the most widely used chemical raw materials in the world, and particularly, the downstream polyolefin industry puts high requirements on the purity of ethylene. In the ethylene produced by naphtha steam cracking technology, acetylene as a byproduct accounts for 1 percent of the content, but the acetylene can poison the catalyst of polymerization reaction to deactivate the catalyst, so that the development of a trace acetylene removal technology in the ethylene is very important. Mainstream cryogenic distillation and catalytic hydrogenation technologies consume very much energy, and metal organic framework materials show great potential in the aspect of ethylene purification because of having special pore channel structures and being capable of adjusting and modifying pore channel sizes and pore channel environments [ Coordination Chemistry Reviews,2019,378,87 ]. Research shows that strong electronegative groups are introduced into the metal organic framework material through structural design and modulation, and the acetylene separation efficiency is extremely high by utilizing the hydrogen bond effect formed by the strong electronegative groups and acetylene.

Disclosure of Invention

Based on the fact that the performance of the existing metal organic framework material in the aspect of acetylene adsorption separation is not ideal enough, the invention aims to design and synthesize a strong electronegativity metal organic framework material with a novel crystal structure. Another object is to provide a process for the preparation thereof.

In order to achieve the purpose, the invention adopts the technical scheme that:

the linear imidazole ligand strong electronegative copper complex has a chemical formula of [ Cu (L)₂SiF₆]Wherein L is a 1, 4-diimidazole benzene ligand (I) having the formula:

the linear imidazole ligand strong-electronegativity copper complex crystal belongs to a monoclinic system, C2/m space group, and is connected by 6-C to form a pcu topological network, the point symbol is {4^12.6^3}, the cell parameters are a ═ 12.755(4), b ═ 25.512(7),

α＝90，β＝117.474(7)，γ＝90°，

the preparation method comprises the following steps:

(1) preparation of L ligand: mixing and uniformly grinding 1, 4-dibromobenzene, imidazole, potassium carbonate and copper sulfate, putting into a polytetrafluoroethylene lining reactor, purging with nitrogen, and putting into an oven for heating reaction; after the reaction is finished, cooling to room temperature, washing with water, carrying out suction filtration, retaining filter residue, extracting, filtering, and carrying out rotary evaporation to obtain a ligand L;

(2) mixing CuSiF₆Dripping the aqueous solution on the bottom layer of the test tube, slowly adding the N, N-dimethylformamide/water mixture into the test tube along the tube wall to serve as a buffer layer, and finally slowly adding the N, N-dimethylformamide solution of the L ligand into the test tube to form a three-layer interface solution;

(3) and (3) covering the layered solution prepared in the step (2), standing at room temperature for reaction, and filtering, washing and drying after the reaction is finished to obtain the linear imidazole ligand electronegative copper complex.

The water used in the step (1) and the step (2) is deionized water, and the preferred molar ratio of the 1, 4-dibromobenzene, the imidazole, the potassium carbonate and the copper sulfate is 100:1200:315: 2.

CuSiF in step (2)₆The concentration of the aqueous solution is 0.09-0.12 mol/L.

In the step (2), the concentration of the L ligand in the N, N-dimethylformamide solution is 0.06-0.08 mol/L.

And (3) in the step (2), the volume ratio of the N, N-dimethylformamide to the water in the buffer solution is 1: 2-2: 1.

As a preferable scheme, the oven reaction temperature in the step (1) is 180 ℃, and the reaction time is 24 hours;

as a preferable mode, the solution of L ligand in N, N-dimethylformamide, the buffer solution of N, N-dimethylformamide/water mixture and CuSiF in the step (2)₆The volume ratio of the aqueous solution is 1:2: 1;

as a preferable mode, the reaction temperature in the step (3) is 25 ℃.

The invention has the following beneficial effects:

the invention synthesizes a novel copper-based three-dimensional layer column crystal structure with strong electronegativity by using a binary linear imidazole ligand, the synthesis method is simple, and the yield reaches more than 80%. The complex three-dimensional structure has a suspended SiF with strong electronegativity₆The catalyst has good adsorption performance on acetylene, has good selectivity, can well remove trace acetylene in ethylene, realizes separation of ethylene and acetylene, meets the requirement of industrial ethylene polymerization reaction on ethylene purity, and has good application prospect in the field of olefin purification.

Drawings

FIG. 1 is a schematic diagram of the synthesis of a complex of the present invention.

FIG. 2 is an asymmetric unit of a complex of the present invention.

FIG. 3 is a diagram of the ligand L linkage of the ligand of the present invention.

FIG. 4 is a metal connection diagram of the ligand of the present invention.

FIG. 5 is a diagram of channels in the c-axis direction of a complex of the present invention.

FIG. 6 is a powder X-ray diffraction pattern of a complex of the present invention, in which 1-the powder X-ray diffraction pattern of a complex of the present invention, 2-is a simulated pattern.

FIG. 7 is a graph showing the isothermal adsorption of ethylene and acetylene by the complex of the present invention at a temperature of 298K.

FIG. 8 is a schematic diagram of a fixed bed separation experiment of the complex of the present invention.

FIG. 9 is a fixed bed separation performance and repeatability test curve of the complex of the present invention at a temperature of 298K with a mixed gas of 99% ethylene/1% acetylene.

Detailed Description

The present invention will be further explained with reference to specific examples, which are not intended to limit the present invention in any way. Unless otherwise indicated, all reagents referred to in the examples are those commonly used in the art.

Example 1

(1) Preparation of ligand L

1, 4-dibromobenzene (2.34g,10mmol), imidazole (2.86g,120mmol), potassium carbonate (4.36g,31.5mmol) and copper sulfate (32mg,0.2mmol) are uniformly ground and then put into a polytetrafluoroethylene lining reactor, and after nitrogen purging for 10 minutes, the polytetrafluoroethylene lining reactor is put into a stainless steel reaction kettle, fastened and put into an oven for reaction at 180 ℃ for 24 hours. After the reaction, the temperature was reduced to room temperature, and the mixture was washed with water (3 × 500mL) by suction filtration to remove inorganic salts and unreacted imidazole; the filter residue is extracted by dichloromethane (3X 100mL), and is dried by adding magnesium sulfate (standing for 3-4 hours) to remove the residual water after extraction, and the product is obtained after filtration and rotary evaporation, wherein the yield is 83 percent.

(2) Preparation of linear imidazole ligand strong electronegative copper complex

10mg of CuSiF₆Dissolving in 0.5mL of water, dripping into the bottom layer of a test tube with the inner diameter of 6mm multiplied by the height of 150mm, slowly adding 1mL of N, N-dimethylformamide/water mixture with the volume ratio of 1:1 into the test tube along the tube wall to serve as a buffer layer, finally dissolving 7.5mg of L ligand in 0.5mL of N, N-dimethylformamide solution, and then slowly adding into the test tube to divide into three distinct layers (see figure 1); and (3) covering the test tube with a cover, standing at 25 ℃ for 7 days at room temperature, and after the reaction is finished, filtering, washing and drying to obtain the linear imidazole ligand electronegative copper complex with the yield of 85%.

Comparative example 1

(1) Preparation of ligand L

The same as in example 1.

Same as example 1, CuSiF₆The dosage of the compound is 20mg, and a large amount of floccule is arranged at the bottom of the test tube without crystal precipitation.

Comparative example 2

(1) Preparation of ligand L

The same as in example 1.

In the same manner as in example 1, the buffer solution used in step (2) was a mixture of N, N-dimethylformamide/ethanol/water in a volume ratio of 6:3:1, and no crystal precipitated.

The complex prepared by the invention has acetylene adsorption capacity of 75mL/g under the conditions of 298K and 1bar, and ethylene is basically not adsorbed (figure 7). In view of this, the separation performance of the complex 99% ethylene/1% acetylene mixed gas was tested by a fixed bed separation device (fig. 8), the acetylene breakthrough time was 90 minutes at 298K, and after 10 cycles, the performance was not attenuated (fig. 9). Compared with similar materials in the literature, the complex has a slightly low acetylene adsorption amount, but almost no adsorption to ethylene is beneficial to ensure that the complex shows extremely excellent ethylene/acetylene separation performance, the performance is not attenuated after 10 cycles, and the material stability is more significant for industrial application.

*Angew.Chem.Int.Ed.2018,57,16067-16071(doi:10.1002/anie.201809884)。

Claims

1. A linear imidazole ligand copper complex is characterized in that the chemical formula is [ Cu (L) ]₂SiF₆]Wherein L is a 1, 4-diimidazole benzene ligand (I) having the formula:

the linear imidazole ligand copper complex crystal belongs to a monoclinic system, namely a C2/m space group, and is connected by 6-C to form a pcu topological network, the point symbol is {4^12.6^3}, and the unit cell parameter is {4^12.6^3}

α＝90°，β＝117.474(7)°，γ＝90°，

2. The method of preparing a linear imidazole ligand copper complex according to claim 1, achieved by the steps of:

(2) mixing CuSiF₆Dripping the aqueous solution on the bottom layer of the test tube, slowly adding the N, N-dimethylformamide/water mixture into the test tube along the tube wall to serve as a buffer layer, and finally slowly adding the N, N-dimethylformamide solution of the L ligand into the test tube to form a three-layer interface solution; CuSiF₆The concentration of the aqueous solution is 0.09-0.12 mol/L;

(3) and (3) covering the layered solution prepared in the step (2), standing at room temperature for reaction, and filtering, washing and drying after the reaction is finished to obtain the linear imidazole ligand copper complex.

3. The method for preparing a linear imidazole ligand copper complex according to claim 2, wherein the concentration of the L ligand in the N, N-dimethylformamide solution in step (2) is 0.06 to 0.08 mol/L.

4. As claimed in claim 2The preparation method of the linear imidazole ligand copper complex is characterized in that in the step (2), N-dimethylformamide solution, N-dimethylformamide/water mixture buffer solution and CuSiF of L ligand₆The volume ratio of the aqueous solution is 1:2: 1.

5. The method for preparing a linear imidazole ligand copper complex according to claim 2, wherein the volume ratio of N, N-dimethylformamide to water in the buffer layer solution in step (2) is 1:2 to 2: 1.