Preparation of metal organic framework material UiO-66 and research of metal organic framework material UiO-66 in catalysis of CO2 conversion

Abstract

The invention relates to an improved UiO-66 synthesis process based on a nitrogen-containing ligand. A metal organic framework material with high specific surface area, thermal stability, chemical stability and mechanical stability is synthesized through a solvothermal method. The specific preparation process comprises the following steps: mixing 4-aminomethyl benzoic acid (4-(Aminomethyl) benzoic acid (AMBA) with terephthalic acid (1, 4-dicarboxybenzene, H2BDC) and zirconium tetrachloride (ZrCl4) according to a certain ratio, transferring the mixture into a crystallization kettle, and synthesizing, so as to obtain the nitrogen modified UiO-66 with different contents, which is recorded as UiO-66-AMBAX. According to the method, the catalysts of the nitrogen-modified UiO-66 with different contents are used for the CO2 cycloaddition reaction, the catalyst shows excellent conversion rate and selectivity, and the reaction conditions are mild.

Description

Technical Field

[0001] The present invention belongs to the field of chemical technology and relates to the preparation of zirconium-based metal organic framework material UiO-66 by using nitrogen-containing ligands of different concentrations and its effect on CO 2 Applications of cycloaddition reactions. Background Art

[0002] In the 21st century, when the economy is highly developed, the main energy used in life and industry is still traditional fossil fuels such as coal, oil and natural gas. Excessive burning of fossil fuels is the main cause of global climate change so far, accounting for more than 75% of global greenhouse gas emissions and all CO 2 Nearly 90% of emissions. So reducing CO in the environment 2 In principle, there are three ways to reduce CO in the environment. 2 The main method is to reduce CO 2 Emissions, CO 2 CO capture and storage (CCS) and CO 2 Capture and Utilization (CCU). At present, CCS technology faces the core problems of high cost and high energy consumption. Secondly, there are environmental risks. If CO 2 If the concentration of the leaked substance increases in the local environment, it may cause soil environmental damage, ocean acidification, and even human CO 2 poisoning, etc. Compared with this, CCU technology is more attractive, capturing CO 2 Not only can it be effectively converted into a variety of valuable products, it also has the advantages of broad economic prospects and low risks. 2 The addition reaction of epoxides to form cyclic carbonates has become the most promising and one of the few industrially scalable CO 2 -containing esters due to its 100% atomic utilization, green and economical process. 2 One of the ways.

[0003] Due to CO 2 The inherent high thermodynamic stability and kinetic inertness make the catalyst an important factor in its transformation. Metal organic frameworks (MOFs) are considered to be excellent catalysts for cycloaddition reactions due to their unique adjustable structure and polarity, high specific surface area, high porosity, good thermal stability and acid and alkali resistance. 6 O 4 (OH) 4 ]Metal clusters and 12 H 2UiO-66, which is connected by BDC coordination, has attracted a lot of attention as one of the MOFs with the largest specific surface area and the best stability. The ideal ligand coordination number of UiO-66 is 12, but there are certain ligand defects in its actual structure. The degree of ligand defects in the UiO-66 structure directly affects the size of its specific surface area. Ligand defects can be regulated by adding different types of ligands. Defects can greatly improve the porosity and reactivity of the material, which is more conducive to cycloaddition reactions. By adding ligands with structures similar to terephthalic acid, competitive coordination can be produced to adjust the catalyst structure, and 4-aminomethylbenzoic acid as a monocarboxylic acid ligand can realize this concept. At the same time, in the cycloaddition reaction, the unsaturated metal site zirconium ion as Lewis acid and the nucleophilic reagent X on the co-catalyst - The presence of a halogenide (usually a halide) can open the epoxide ring, while the presence of a Lewis base (amino or nitrogen-containing substances) can further activate CO 2 To accelerate CO 2 Cycloaddition reaction to improve its reactivity. We chose 4-aminomethylbenzoic acid as a ligand mainly to explore the effect of the catalyst on the cycloaddition reaction by introducing different amounts of amino groups. Summary of the invention

[0004] We synthesized Zr-MOF materials using 4-aminomethylbenzoic acid as a ligand in different proportions to explore the effect of 4-aminomethylbenzoic acid on the structure, specific surface area, pore volume, etc. of UiO-66. At the same time, we compared it in the cycloaddition reaction to observe its effect on CO 2 The purpose of the present invention is to provide a method for preparing a catalyst having an amino group, which has a simple preparation process, low cost, mild reaction conditions, and the catalyst has the characteristics of high thermal stability, high porosity and large specific surface area, and has a high adsorption capacity for CO 2 It has good catalytic ability in cycloaddition reaction with epoxides.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is: A method for preparing a zirconium-based metal organic framework material UiO-66 regulated by a nitrogen-containing ligand, wherein the reaction is carried out according to the following reaction equation:

[0006] The preparation method of zirconium-based metal organic framework material UiO-66 containing different molar ratios of 4-aminomethylbenzoic acid comprises the following steps:

[0007] (1) Zirconium tetrachloride (ZrCl 4 ) were dispersed in 25 mL of DMF and completely dissolved by sonication;

[0008] (2) Disperse different proportions of mixed ligands (terephthalic acid and 4-aminomethylbenzoic acid) in 25 mL of DMF and dissolve them completely by ultrasonication;

[0009] (3) The molar ratio of zirconium tetrachloride to the mixed ligand is 1:1;

[0010] (4) After the above metal source and ligand solution are mixed and dissolved by ultrasonication, they are placed in a stainless steel reactor lined with polytetrafluoroethylene, placed in a homogeneous reactor and reacted at 120 °C. After crystallization for 24 h, the desired solid is obtained; After the reaction was completed, the stainless steel reactor was cooled to room temperature, the solid product was collected by centrifugation, and washed with DMF and methanol for several times;

[0011] (5) Place the washed solid in a vacuum drying oven and dry at 60 °C for 24 h. Collect the obtained white solid sample, grind it into powder, and seal it for storage.

[0012] An application of the zirconium-based metal organic framework material UiO-66 containing different molar ratios of 4-aminomethylbenzoic acid as described above, and the obtained catalyst is subjected to CO 2 The specific operation process of the reaction of preparing cyclic carbonate by cycloaddition reaction with epoxy compounds is as follows.

[0013] As a preferred technical solution, the catalyst needs to be activated in a vacuum drying oven at 80°C for 12 h before the cycloaddition reaction test.

[0014] As a preferred technical solution, propylene oxide (PO) is used as a substrate and tetrabutylammonium bromide (TBAB) is used as a co-catalyst to catalyze the cycloaddition reaction.

[0015] As a preferred technical solution, the amount of tetrabutylammonium bromide added as a co-catalyst is 0.5 mol% of propylene oxide.

[0016] As a preferred technical solution, 0.05 g of the UiO-66 catalyst containing different molar ratios of 4-aminomethylbenzoic acid as described above is taken.

[0017] As a preferred technical solution, in CO 2 In the reaction of preparing cyclocarbonate by cycloaddition of epoxy compounds, the reaction temperature is 80-100 °C, CO 2 The pressure is 1 MPa and the reaction time is 4 to 8 h.

[0018] As a preferred technical solution, after the reaction is completed and cooled to room temperature, 8 mL of ethyl acetate is used as a solvent to transfer the reactants to a 10 mL centrifuge tube, and wait for gas chromatography-mass spectrometry (GC-MS) detection for qualitative and quantitative determination.

[0019] Compared with the prior art, the technical solution of the present invention has the following beneficial effects.

[0020] (1) The present invention successfully prepared a single-step synthesis method containing a defective structure and an amino group (−NH 2 Compared with post-synthetic modification technology, this method has a simple operation process and shortens the production time.

[0021] (2) Mixing cheap 4-aminomethylbenzoic acid with terephthalic acid to prepare UiO-66 saves costs.

[0022] (3) The zirconium-based metal organic framework catalyst provided by the present invention is used in the CO 2 The reaction conditions for the cycloaddition reaction with epoxides are mild, and the activity of the catalyst containing amino groups is higher than that of the catalyst without amino groups, indicating that the amino groups play a certain role in the cycloaddition reaction. The presence of Lewis bases (amino groups or nitrogen-containing substances) can activate CO 2 To accelerate CO 2 Cycloaddition reaction rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 For UiO-66-AMBA X X-ray diffraction patterns of the catalysts.

[0024] Figure 2 For UiO-66-AMBA X Nitrogen adsorption-desorption curves.

[0025] Figure 3 For UiO-66-AMBA X Pore ​​size distribution diagram. DETAILED DESCRIPTION

[0026] In combination with the accompanying drawings and technical solutions, the specific implementation of the present invention is further described below. Regarding the specific preparation method of UiO-66 material regulated by nitrogen-containing ligands: Example 1

[0027] UiO-66-AMBA 0 Preparation method:

[0028] (1) Dissolve zirconium chloride (4 mmol, 0.95 g) in 25 mL of DMF and mix thoroughly by ultrasonication.

[0029] (2) Dissolve terephthalic acid (4 mmol, 0.66 g) in 25 mL of DMF and mix thoroughly by ultrasonication.

[0030] (3) After mixing the two liquids, ultrasonically disperse them again to make them uniformly dispersed, and then transfer the solution to a reaction vessel, i.e., a stainless steel autoclave with a 100 mL polytetrafluoroethylene liner, and react in an oven at 120 °C for 24 h.

[0031] (4) After cooling to room temperature, the sample was centrifuged and then washed repeatedly with DMF and methanol three times each.

[0032] (5) The product was dried at 60°C for one day, and then the obtained material was ground into powder to obtain the catalyst UiO-66-AMBA. 0 . Example 2

[0033] UiO-66-AMBA 0.1 Preparation method:

[0034] (1) Dissolve zirconium chloride (4 mmol, 0.95 g) in 25 mL of DMF and mix thoroughly by ultrasonication.

[0035] (2) Dissolve 4-aminomethylbenzoic acid (0.4 mmol, 0.06 g) and terephthalic acid (3.6 mmol, 0.60 g) in 25 mL of DMF and mix them by ultrasonication.

[0036] (3) After mixing the two liquids, ultrasonically disperse them again to make them uniformly dispersed, and then transfer the solution to a reaction vessel, i.e., a stainless steel autoclave with a 100 mL polytetrafluoroethylene liner, and react in an oven at 120 °C for 24 h.

[0037] (4) After cooling to room temperature, the sample was centrifuged and then washed repeatedly with DMF and methanol three times each.

[0038] (5) The product was dried at 60°C for one day, and then the obtained material was ground into powder to obtain the catalyst UiO-66-AMBA. 0.1 . Example 3

[0039] UiO-66-AMBA 0.2 Preparation method:

[0040] (1) Dissolve zirconium chloride (4 mmol, 0.95 g) in 25 mL of DMF and mix thoroughly by ultrasonication.

[0041] (2) Dissolve 4-aminomethylbenzoic acid (0.8 mmol, 0.12 g) and terephthalic acid (3.2 mmol, 0.53 g) in 25 mL of DMF and mix well by ultrasonication.

[0042] (3) After mixing the two liquids, ultrasonically disperse them again to make them uniformly dispersed, and then transfer the solution to a reaction vessel, i.e., a stainless steel autoclave with a 100 mL polytetrafluoroethylene liner, and react in an oven at 120 °C for 24 h.

[0043] (4) After cooling to room temperature, the sample was centrifuged and then washed repeatedly with DMF and methanol three times each.

[0044] (5) The product was dried at 60°C for one day, and then the obtained material was ground into powder to obtain the catalyst UiO-66-AMBA. 0.2 . Example 4

[0045] UiO-66-AMBA 0.3 Preparation method:

[0046] (1) Dissolve zirconium chloride (4 mmol, 0.95 g) in 25 mL of DMF and mix thoroughly by ultrasonication.

[0047] (2) Dissolve 4-aminomethylbenzoic acid (1.2 mmol, 0.18 g) and terephthalic acid (2.8 mmol, 0.46 g) in 25 mL of N,N-dimethylformamide (DMF) and mix them by ultrasonication.

[0048] (3) After mixing the two liquids, ultrasonically disperse them again to make them uniformly dispersed, and then transfer the solution to a reaction vessel, i.e., a stainless steel autoclave with a 100 mL polytetrafluoroethylene liner, and react in an oven at 120 °C for 24 h.

[0049] (4) After cooling to room temperature, the sample was centrifuged and then washed repeatedly with DMF and methanol three times each.

[0050] (5) The product was dried at 60°C for one day, and then the obtained material was ground into powder to obtain the catalyst UiO-66-AMBA. 0.3 .

[0051] On the CO responsiveness of UiO-66 materials regulated by nitrogen-containing ligands 2 Specific operation method of cycloaddition reaction with epoxide: Weigh 0.05 g of the catalyst UiO-66-AMBA on a balance. X and TBAB in a polytetrafluoroethylene liner. Use a pipette to add (20 mmol, 1.4 mL) of propylene oxide into the polytetrafluoroethylene liner, and fill the reactor with 1 MPa of CO. 2Gas. The above liner was placed in a reactor and heated to 80-100 °C for 4-8 h at a speed of 720 rpm. After the reaction was completed and cooled to room temperature, 8 mL of ethyl acetate was used as a solvent to transfer the reactants to a 10 mL centrifuge tube, and the quantitative analysis was performed using a gas chromatograph (GC), and the qualitative analysis was performed using a gas chromatography-mass spectrometry (GC-MS). Example 5

[0052] The co-catalyst TBAB (0.03 g) and the catalyst UiO-66-AMBA 0 (0.05 g) was added to a high pressure reactor and stirred at 80 °C for 4 h to obtain a mixture containing propylene carbonate product. According to gas chromatography analysis, the propylene oxide conversion rate was 64% and the propylene carbonate product selectivity was 97%. Example 6

[0053] The co-catalyst TBAB (0.03 g) and the catalyst UiO-66-AMBA 0.1 (0.05 g) was added to a high pressure reactor and stirred at 80 °C for 4 h to obtain a mixture containing propylene carbonate product. According to gas chromatography analysis, the propylene oxide conversion rate was 76% and the propylene carbonate product selectivity was 98%. Example 7

[0054] The co-catalyst TBAB (0.03 g) and the catalyst UiO-66-AMBA 0.2 (0.05 g) was added to a high-pressure reactor and stirred at 80 °C for 4 h to obtain a mixture containing propylene carbonate product. According to gas chromatography analysis, the propylene oxide conversion rate was 65% and the propylene carbonate product selectivity was 97%. Example 8

[0055] The co-catalyst TBAB (0.03 g) and the catalyst UiO-66-AMBA 0.3 (0.05 g) was added to a high-pressure reactor and stirred at 80 °C for 4 h to obtain a mixture containing propylene carbonate product. According to gas chromatography analysis, the propylene oxide conversion rate was 70% and the propylene carbonate product selectivity was 97%. Example 9

[0056] The co-catalyst TBAB (0.03 g) and the catalyst UiO-66-AMBA 0 (0.05 g) was added to a high pressure reactor and stirred at 100 °C for 4 h to obtain a mixture containing propylene carbonate product. According to gas chromatography analysis, the propylene oxide conversion rate was 88% and the propylene carbonate product selectivity was 99%.

[0057] Embodiment 10: The co-catalyst TBAB (0.03 g) and the catalyst UiO-66-AMBA 0.1 (0.05 g) was added to a high pressure reactor and stirred at 100 °C for 4 h to obtain a mixture containing propylene carbonate product. According to gas chromatography analysis, the propylene oxide conversion rate was 94% and the propylene carbonate product selectivity was 99%.

[0058] Embodiment 11: The co-catalyst TBAB (0.03 g) and the catalyst UiO-66-AMBA 0.2 (0.05 g) was added to a high pressure reactor and stirred at 100 °C for 4 h to obtain a mixture containing propylene carbonate product. According to gas chromatography analysis, the propylene oxide conversion rate was 92% and the propylene carbonate product selectivity was 99%.

[0059] Embodiment 12: The co-catalyst TBAB (0.03 g) and the catalyst UiO-66-AMBA 0.3 (0.05 g) was added to a high pressure reactor and stirred at 100 °C for 4 h to obtain a mixture containing propylene carbonate product. According to gas chromatography analysis, the propylene oxide conversion rate was 91% and the propylene carbonate product selectivity was 99%.

[0060] Embodiment 13: The co-catalyst TBAB (0.03 g) and the catalyst UiO-66-AMBA 0 (0.05 g) was added to a high-pressure reactor and stirred at 80 °C for 8 h to obtain a mixture containing propylene carbonate product. According to gas chromatography analysis, the propylene oxide conversion rate was 85% and the propylene carbonate product selectivity was 98%.

[0061] Embodiment 14: The co-catalyst TBAB (0.03 g) and the catalyst UiO-66-AMBA 0.1 (0.05 g) was added to a high-pressure reactor and stirred at 80 °C for 8 h to obtain a mixture containing propylene carbonate product. According to gas chromatography analysis, the propylene oxide conversion rate was 91% and the propylene carbonate product selectivity was 99%.

[0062] Embodiment 15: The co-catalyst TBAB (0.03 g) and the catalyst UiO-66-AMBA 0.2(0.05 g) was added to a high pressure reactor and stirred at 80 °C for 8 h to obtain a mixture containing propylene carbonate product. According to gas chromatography analysis, the propylene oxide conversion rate was 88% and the propylene carbonate product selectivity was 99%.

[0063] Embodiment 16: The co-catalyst TBAB (0.03 g) and the catalyst UiO-66-AMBA 0.3 (0.05 g) was added to a high-pressure reactor and stirred at 80 °C for 8 h to obtain a mixture containing propylene carbonate product. According to gas chromatography analysis, the propylene oxide conversion rate was 89% and the propylene carbonate product selectivity was 99%.

[0064] The conversion rate, selectivity and yield of the cycloaddition reaction were calculated, and the reaction results are shown in the following table: Table 1. CO 2 Cycloaddition reaction with propylene oxide catalyst Temperature / ℃ Time / h Conversion rate Selectivity <![CDATA[UiO-66-AMBA 0.0 ]]> 80 4 64 97 <![CDATA[UiO-66-AMBA 0.1 ]]> 80 4 76 98 <![CDATA[UiO-66-AMBA 0.2 ]]> 80 4 65 97 <![CDATA[UiO-66-AMBA 0.3 ]]> 80 4 70 97 Table 2. CO after increasing temperature 2 Cycloaddition reaction with propylene oxide catalyst Temperature / ℃ Time / h Conversion rate Selectivity <![CDATA[UiO-66-AMBA 0.0 ]]> 100 4 88 99 <![CDATA[UiO-66-AMBA 0.1 ]]> 100 4 94 99 <![CDATA[UiO-66-AMBA 0.2 ]]> 100 4 92 99 <![CDATA[UiO-66-AMBA 0.3 ]]> 100 4 91 99 Table 3. CO after increasing time 2 Cycloaddition reaction with propylene oxide catalyst Temperature / ℃ Time / h Conversion rate Selectivity <![CDATA[UiO-66-AMBA 0.0 ]]> 80 8 85 98 <![CDATA[UiO-66-AMBA 0.1 ]]> 80 8 91 99 <![CDATA[UiO-66-AMBA 0.2 ]]> 80 8 88 99 <![CDATA[UiO-66-AMBA 0.3 ]]> 80 8 89 99

Claims

1. A method for preparing a zirconium-based metal organic framework material UiO-66 containing different molar ratios of 4-aminomethylbenzoic acid, characterized in that: The following steps are involved: (1) The zirconium source and the organic ligand are placed in an equal amount of DMF, respectively, and after ultrasonic mixing, a regulator is added to the mixed solution and ultrasonically mixed again to make it uniform; (2) placing the mixed solution of step (1) in a reaction kettle for high-temperature synthesis in a homogeneous reactor, and then centrifuging and discarding the clear liquid to obtain a white product; (3) The white product obtained in step (2) is heated and dried to obtain the zirconium-based metal organic framework material UiO-66-AMBA. X .

2. The method for preparing the zirconium-based metal organic framework material UiO-66 according to claim 1, characterized in that: The zirconium source is zirconium tetrachloride.

3. The method for preparing the zirconium-based metal organic framework material UiO-66 according to claim 1, characterized in that: The organic ligands are terephthalic acid and 4-aminomethylbenzoic acid.

4. The method for preparing the zirconium-based metal organic framework material UiO-66 according to any one of claims 1 to 3, characterized in that: The molar ratio of the zirconium source to the organic ligand is 1:

1.

5. The method for preparing the zirconium-based metal organic framework material UiO-66 according to claim 1, characterized in that: In step (1), the zirconium source and the organic ligand solvent DMF are both 25 mL, and the molar ratio of the ligand 4-aminomethylbenzoic acid to terephthalic acid is (X:1-X), that is, 0:1, 1:9, 2:8, and 3:7, respectively. The catalyst is named UiO-66-AMBA0, UiO-66-AMBA 0.1 , UiO-66-AMBA 0.2 , UiO-66-AMBA 0.3 .

6. The method for preparing the zirconium-based metal organic framework material UiO-66 according to claim 1, characterized in that: In step (2), UiO-66 is heated at 120 °C for 24 h in a homogeneous reactor.

7. The method for preparing the zirconium-based metal organic framework material UiO-66 according to claim 1, characterized in that: In step (3), the heating and drying is performed in a vacuum drying oven at 60° C. for 24 h.

8. Zirconium-based metal organic framework material UiO-66 containing different molar ratios of 4-aminomethylbenzoic acid, characterized in that: The method is obtained by the preparation method according to any one of claims 1 to 7.

9. The use of the zirconium-based metal organic framework material UiO-66 as claimed in claim 8, characterized in that: The zirconium-based metal-organic framework material UiO-66 was used for CO2 cycloaddition reaction using propylene oxide as substrate.

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