Preparation and application of imidazole column aromatic hydrocarbon impregnated silicon carbon dioxide adsorption material

Abstract

The invention provides a preparation method of an imidazole column aromatic hydrocarbon impregnated silicon carbon dioxide adsorption material and application of selective adsorption and separation of carbon dioxide. According to the invention, under the protection of nitrogen, a dibromo phenol ether derivative 1, 4-bis (2-bromoethoxy) benzene of 1, 4-benzenediol is used as a module to prepare the bromoethoxy substituted brominated pillararene. And further modifying the brominated pillararene with 2-aminoimidazole to prepare the aminoimidazole modified brominated pillararene. And finally, impregnating the amino imidazole modified brominated column aromatic hydrocarbon into the porous silicon dioxide by adopting a multi-step impregnation method to prepare the imidazole column aromatic hydrocarbon impregnated silicon carbon dioxide adsorption material. The imidazole column aromatic hydrocarbon impregnated silicon carbon dioxide adsorption material provided by the invention is rich in active action sites, wide in pore size distribution range and designable in structure. The adsorption material shows good adsorption and selective separation capability on carbon dioxide. In addition, the adsorption material has good repeatability and stability.

Description

Technical Field

[0001] The invention relates to the preparation of an imidazole column aromatic hydrocarbon impregnated silicon carbon dioxide adsorption material and its application in high-efficiency adsorption and selective separation of carbon dioxide, belonging to the technical field of environment and energy utilization. Background Art

[0002] Carbon dioxide (CO) in flue gases from burning fossil fuels 2 ) is an important cause of the "greenhouse effect". With the further intensification of industrialization, if no action is taken or emission reduction control is carried out, CO 2 The concentration of CO2 will further increase, seriously threatening the environment and human health. The climate change caused by this, such as the 1-3 mm annual rise in sea level, is caused by atmospheric CO2. 2 concentration. In addition, ocean acidification caused by carbon dioxide is believed to have an impact on organisms and ecosystems. Currently, carbon capture and storage / sequestration, carbon capture and utilization are one of the key research topics in the field of solving environmental pollution problems today.

[0003] In recent years, porous carbon, zeolite molecular sieves, resins, porous organic polymers, metal-organic frameworks, covalent organic frameworks, and ionic liquids have been widely used in CO 2 However, among many materials, supramolecular macrocyclic compounds such as crown ethers, cyclodextrins, calix[n]arene and cucurbituril have macrocyclic cavities and can be used in CO adsorption after functional modification. 2 Therefore, functionalization of supramolecular macrocyclic main body is expected to develop CO 2 Adsorption materials for CO 2 As a new type of supramolecular macrocyclic host, pillar[5]arene has many advantages in CO catalysis due to its high yield, easy functionalization and self-cavity. 2 It has good research prospects in adsorption.

[0004] Based on this, the present invention proposes a new method for effectively preparing an imidazole column aromatic hydrocarbon impregnated silicon carbon dioxide adsorption material, and applies it to CO 2 Study on efficient adsorption and selective separation. Investigate the effects of changes in the pore structure of adsorbent materials, functional groups, temperature and gas flow rate on CO 2 Dynamic adsorption capacity changes, and CO 2 / CH 4 , CO 2 / N 2 The effect of selective separation performance. It is expected that the adsorbent can be applied to actual CO 2 In the field of adsorption separation, it has important research value and application prospects. Summary of the invention

[0005] The purpose of the present invention is to provide a simple and efficient preparation method and use of imidazole column aromatic hydrocarbon impregnated silicon carbon dioxide adsorbent material, to develop new types of imidazole column aromatic hydrocarbon adsorbents, and the imidazole column aromatic hydrocarbon impregnated silicon adsorbent material prepared by the method has good CO 2 It has high adsorption performance and separation selectivity.

[0006] 1. Preparation of Imidazole Column Aromatic Hydrocarbon Impregnated Silicon Carbon Dioxide Adsorption Material (1) 1,4-benzenediol and ethylene dibromide are subjected to reflux reaction in the presence of potassium hydroxide and potassium iodide as catalysts and acetonitrile as solvent at 75-80°C for 20-24 hours. The solid obtained after vacuum distillation is purified by column chromatography to obtain 1,4-bis(2-bromoethoxy)benzene.

[0007] Among them, the molar ratio of 1,4-benzenediol to ethylene dibromide is 1:2~1:3; the molar ratio of 1,4-benzenediol to potassium hydroxide is 1:1~1:1.5; the molar ratio of 1,4-benzenediol to potassium iodide is 1:2~1:2.5.

[0008] (2) 1, 4-bis(2-bromoethoxy)benzene is used as a structural module, boron trifluoride etherate is used as a catalyst, polyformaldehyde is used as a bridging polymerization agent, and dry 1, 2-dichloromethane is used as a reaction solvent. The reaction is carried out at room temperature under a nitrogen atmosphere for 1.5 to 2.0 hours. After the reaction is completed, methanol is poured into the reaction mixture to terminate the reaction. The mixture is extracted with water and a saturated sodium bicarbonate solution. The organic phase is dried over anhydrous magnesium sulfate. The solid obtained after vacuum distillation is then subjected to column chromatography to obtain brominated columnar aromatics substituted with bromoethoxy.

[0009] Among them, the mass ratio of boron trifluoride ether to 1, 4-bis(2-bromoethoxy)benzene is 1:1~1:1.5; the mass ratio of 1, 4-bis(2-bromoethoxy)benzene to paraformaldehyde is 1:0.5~1:1.0.

[0010] The synthesis and structure of bromoethoxy-substituted brominated pillar aromatics are as follows: (3) The brominated columnar aromatic hydrocarbon substituted with bromoethoxy and 2-aminoimidazole are dissolved in an acetone-acetonitrile mixed solvent, diethylamine is used as a catalyst, and the reaction is carried out at 85-90°C for 10-12 hours. After the reaction is completed, the columnar aromatic hydrocarbon modified with 2-aminoimidazole is directly distilled under reduced pressure to obtain the columnar aromatic hydrocarbon. The molar ratio of the brominated columnar aromatic hydrocarbon substituted with bromoethoxy to 2-aminoimidazole is 1:10-1:15. The acetone-acetonitrile mixed solvent has a volume ratio of acetone to acetonitrile of 1:1.

[0011] The synthesis and structure of 2-aminoimidazole modified pillar arene are as follows: (4) Dissolve 2-aminoimidazole modified columnar aromatic hydrocarbon in acetone-acetonitrile solution, disperse porous silica in the solution, immerse for 10-12 hours at room temperature and pressure, and then dry to complete one immersion. Repeat the immersion process twice. Finally, the obtained solid material is dried, calcined, and sieved with 20-40 mesh to obtain imidazole columnar aromatic hydrocarbon impregnated silicon carbon dioxide adsorption material.

[0012] The mass concentration of 2-aminoimidazole modified pillar aromatic hydrocarbon in the acetone-acetonitrile solution is 30%-40%, the mass ratio of 2-aminoimidazole modified pillar aromatic hydrocarbon to porous silica is 1:3-1:5, and the volume ratio of acetone to acetonitrile in the acetone-acetonitrile solution is 1:1.

[0013] 2. Characterization of Imidazole Column Aromatic Hydrocarbon Impregnated Silicon Carbon Dioxide Adsorption Material Infrared spectrum of imidazole column aromatic hydrocarbon impregnated silicon carbon dioxide adsorption material Figure 3 As shown, 3550~3300 cm -1 The broad peak at 3432 cm -1 The wavenumbers are assigned to the stretching vibration peaks of N−H and Si−OH of 2-aminoimidazole, 2929 and 2852 cm −1 The characteristic peaks at 1645 cm-1 belong to the symmetric and asymmetric stretching vibrations of the C-H bonds in the alkyl chain. -1 The characteristic peak at 1511 cm is the -C=N double bond stretching vibration peak of the imidazole ring in the 2-aminoimidazole structure, while the peak at 1511 cm -1 The characteristic peak at 1415 cm is attributed to the C=C stretching vibration peak of the imidazole ring in the 2-aminoimidazole structure in the imidazole-modified column aromatic impregnated silicon-based adsorbent material. -1 The characteristic peaks at 1096, 806, and 462 cm −1 These characteristic peaks are attributed to the vibration peaks of Si-O-Si bonds. The above infrared data confirm the successful preparation of imidazole-modified columnar aromatics impregnated silicon-based adsorbent materials.

[0014] Scanning electron microscopy of imidazole column aromatic hydrocarbon impregnated silicon carbon dioxide adsorption material Figure 4 As shown in the figure, the imidazole-modified column aromatic hydrocarbon impregnated silica gel material presents a morphology of silica sphere stacking particles, and the surface of the material is rough, indicating that the material was successfully prepared.

[0015] Thermogravimetric analysis of imidazole modified column aromatic hydrocarbon impregnated silica-based adsorbent material Figure 5 Thermogravimetric curve analysis shows that SiO 2 In N 2It has high thermal stability under protective atmosphere, and its weight loss rate is only 6% even when heated to 750 ℃. The thermal stability of columnar aromatics impregnated silica gel and imidazole-modified columnar aromatics impregnated silica gel is also very good, and the temperature range of the stage with faster mass loss is 260~750 ℃. This may be due to the decomposition, combustion and volatilization of columnar aromatics or imidazole groups in the adsorbent. The final loss rates of columnar aromatics impregnated silica gel and imidazole-modified columnar aromatics impregnated silica gel are 11% and 17%, respectively.

[0016] N-type carbon dioxide adsorbent material impregnated with imidazole aromatics 2 Adsorption / desorption and BJH pore size distribution spectra are shown in Figure 6 The test results show that the imidazole-modified column aromatic hydrocarbon-impregnated silicon-based adsorbent material has a typical IV type N 2 Desorption curve, its surface area is 240 m² / g, which is larger than SiO 2 The porous material (261 m² / g) was reduced, indicating that the imidazole column aromatic hydrocarbon impregnated silicon carbon dioxide adsorption material has a mesoporous pore structure and was successfully prepared.

[0017] 3. Application of High Efficiency Adsorption and Selective Separation of Carbon Dioxide Gas flow rate is closely related to mass transfer and is an important factor affecting the adsorption capacity of porous solid materials. The gas flow rate of imidazole column aromatic impregnated silicon carbon dioxide adsorption material was investigated ( Figure 7 ), at 30 °C, the material was subjected to a fixed bed at atmospheric pressure with a gas flow rate of 0.2 g for CO 2 Dynamic adsorption experiment. The adsorption experiment showed that as the gas flow rate increased from 10 to 40 ml / min, CO 2 The saturated adsorption time and breakthrough process time are shortened at the same time. When the gas flow rate is 10 ml / min, the dynamic saturated adsorption capacity of the adsorbent reaches the maximum value of 6.6 mmol / g. With the further increase of gas flow rate, the saturated adsorption capacity of the material shows a downward trend. At this time, the amino groups on the surface of the imidazole column aromatic impregnated silicon carbon dioxide adsorption material have been combined with CO 2 Fully react to form a stable structure, CO 2 The mass transfer resistance increases, making it difficult to fully react further, and the contact time is shortened to reduce CO 2 Saturated adsorption capacity.

[0018] Temperature and CO 2 The dynamic adsorption capacity has a significant impact. Figure 8 The adsorption of CO at a flow rate of 10 ml / min was investigated in the adsorption temperature range of 30-60 °C. 2 The experimental data show that as the temperature increases, CO 2 The saturated adsorption capacity increases. When the temperature is 40 ℃, the CO2 The saturated adsorption capacity reached 6.8 mmol / g, but further increase in temperature would lead to a decrease in the adsorption capacity, indicating that the material has a low adsorption capacity for CO 2 The adsorption of CO may be a kinetically controlled process. 2 Desorption at the adsorption sites within the pores may be more preferential, leading to CO 2 Adsorption decreased.

[0019] like Fig. 9 As shown in Figure 2, the effect of adsorption material dosage on CO at a flow rate of 10 ml / min at 40 °C was investigated. 2 The experimental results show that as the mass of the imidazole column aromatic impregnated silicon carbon dioxide adsorption material increases from 0.2 to 0.8 g, the breakthrough time gradually shortens. 2 The saturated adsorption capacity decreased, indicating that the adsorption capacity of the material for acidic gases may be related to the ratio of amines. 2 The adsorption capacity of CO is enhanced, and the adsorption mode is the dominant adsorption mode. 2 The diffusion resistance of the adsorbent material increases, thereby reducing CO 2 ability.

[0020] In addition, compared with SiO 2 , columnar aromatics impregnated silica gel and imidazole columnar aromatics impregnated silica adsorption materials for CO 2 adsorption capacity. Fig.10 As shown in the figure, it was found that the imidazole aromatics impregnated silicon adsorbent material has a high CO 2 The saturated adsorption capacity of is the highest. This indicates that the bonding of 2-aminoimidazole to the columnar aromatics greatly improves the CO 2 The adsorption capacity of CO was significantly increased by 2-aminoimidazole and bromoethoxy-substituted brominated aromatic hydrocarbons. 2 adsorption performance.

[0021] In order to further evaluate the actual separation performance of imidazole column aromatics impregnated silicon adsorbent material, dynamic separation selectivity experiments were performed to evaluate the CO separation under optimal conditions. 2 / CH 4 and CO 2 / N 2 The influence of dynamic adsorption on the selective separation performance. Fig.11 , 12 As shown, during the whole adsorption process, CO 2 The breakthrough time of CH 4 and N 2 The adsorption time is long, indicating that CO 2 The breakthrough curve shows that the imidazole column aromatic hydrocarbon impregnated silicon adsorbent has a strong adsorption capacity for CO 2 , CH4 and N 2 Has good separation potential.

[0022] In order to further explore the practical industrial application prospects and application value of imidazole column aromatics impregnated silicon adsorbent materials, the cyclic regeneration performance of continuous CO 2 Dynamic adsorption evaluation. Specifically, a binary CO 2 The regeneration performance of the standard was evaluated by using / Ar as the adsorption agent. 2 Dynamic adsorption was performed, and then desorption cycles were performed at 110 °C with pure argon as carrier gas at a flow rate of 15 ml / min. 2 The adsorption capacity data can be obtained ( Fig.13 ), after 15 consecutive adsorptions, the saturated adsorption capacity of the adsorbent was 6.0 mmol / g. The results show that the imidazole pillar aromatics impregnated silicon adsorbent prepared by 2-aminoimidazole modified pillar aromatics has good cyclic regeneration performance.

[0023] In summary, the present invention proposes a simple and efficient new preparation method and new use of an imidazole column aromatic hydrocarbon impregnated silicon carbon dioxide adsorbent material. Under nitrogen protection, the present invention uses 1,4-diphenol derivative 1,4-bis(2-bromoethoxy)benzene as a structural module to prepare a bromoethoxy-substituted brominated column aromatic hydrocarbon raw material. Then, porous silicon is dispersed in an acetone-acetonitrile solution containing bromoethoxy-substituted brominated column aromatic hydrocarbons, and the imidazole column aromatic hydrocarbon impregnated silicon carbon dioxide adsorbent material is prepared by multiple impregnation methods. The imidazole column aromatic hydrocarbon impregnated silicon adsorbent material has a high CO2 absorption capacity. 2 The adsorption capacity is 6.8 mmol / g. By studying the changes in the pore structure of imidazole column aromatic hydrocarbon impregnated silicon adsorption materials, CO 2 Adsorption performance and CO 2 Dynamic adsorption and CO 2 / CH 4 , CO 2 / N 2 This indicates that the introduction of 2-aminoimidazole in the imidazole columnar aromatics impregnated silicon adsorbent provides amine active sites, and the cavity of the columnar aromatics provides a pore structure that is conducive to adsorption, thereby promoting CO 2 After 15 cycles of regeneration, the dynamic saturated adsorption capacity can still reach 6.0 mmol / g, which is a CO adsorption method with research value. 2 Adsorbent material. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the hydrogen nuclear magnetic resonance spectrum of 1,4-bis(2-bromoethoxy)benzene; Figure 2 This is the H NMR spectrum of bromoethoxy-substituted brominated aromatic hydrocarbons; Figure 3 (a) SiO 2 , infrared spectra of (b) brominated pillared arene, (c) pillared arene impregnated silica gel and (d) imidazole pillared arene impregnated silica adsorption materials; Figure 4 This is a scanning electron microscope image of imidazole column aromatics impregnated silicon adsorbent material; Figure 5 (a) SiO 2 , Thermogravimetric graphs of (b) pillared aromatics impregnated silicon and (c) imidazole pillared aromatics impregnated silicon adsorbent materials; Figure 6 Nitrogen adsorption / desorption isotherms for imidazole column aromatic impregnated silicon adsorbent material; Figure 7 is the flow rate to CO 2 Effect of dynamic adsorption performance; Figure 8 is the adsorption temperature and 2 Effect of adsorption performance; Fig. 9 is the adsorbent dosage for CO 2 Effect of adsorption performance; Fig.10 CO for different adsorbent materials 2 Adsorption performance; Fig.11 Imidazole aromatics impregnated silicon adsorbent material for CO 2 / CH 4 Selective separation performance (the inset shows the dynamic saturated adsorption capacity); Fig.12 Imidazole aromatics impregnated silicon adsorbent material for CO 2 / N 2 Selective separation performance (the inset shows the dynamic saturated adsorption capacity); Fig.13 Imidazole aromatics impregnated silicon adsorbent for CO 2 Recyclability. DETAILED DESCRIPTION

[0025] The present invention will be further described below by way of examples. Example

[0026] (1) 6.5 g (60 mmol) of 1,4-benzenediol, 22.5 g (120 mmol) of ethylene dibromide, 2.4 g (60 mmol) of potassium hydroxide and 20.0 g (120 mmol) of potassium iodide were added to 400 ml of acetone solution, reacted at 80°C for 24 hours, filtered with a sand core funnel and washed with dichloromethane. After filtration, the solution was distilled under reduced pressure, purified by silica gel column chromatography (petroleum ether: dichloromethane, 20 / 1, v / v) and vacuum dried to obtain 1, 4-bis(2-bromoethoxy)benzene. The NMR data of 1, 4-bis(2-bromoethoxy)benzene are δ(ppm):6.79 (s, 4H), 4.18 (t, J = 6.0 Hz, 4H), 3.54 (t, J =6.0 Hz, 4H), proving the successful synthesis of 1, 4-bis(2-bromoethoxy)benzene. The NMR spectrum is shown in Figure 1 shown.

[0027] (2) Add 3.5 g (10 mmol) of 1, 4-bis(2-bromoethoxy)benzene, 2.86 g (20 mmol) of boron trifluoride etherate, and 1.0 g of paraformaldehyde to 60 ml of 1, 2-dichloromethane and react at room temperature for 2.0 hours. After the reaction is completed, pour 80-100 ml of methanol to quench the reaction. Wash the reaction mixture with 30-40 ml of water and 20-30 ml of saturated sodium bicarbonate solution. Then, dry the organic layer with 15-20 g of anhydrous magnesium sulfate and remove the organic solvent by vacuum distillation. Separate by petroleum ether: dichloromethane (10:1, volume ratio) column chromatography to obtain bromoethoxy-substituted brominated aromatic hydrocarbons. Bromoethoxy substituted brominated aromatic hydrocarbons NMR δ (ppm): 6.91 (s, 10H), 4.23 (t, J = 6.0 Hz, 20H), 3.84 (s, 10H), 3.63 (t, J = 4.0 Hz, 20H) proved the successful synthesis of bromoethoxy substituted brominated aromatic hydrocarbons. The NMR spectrum is shown in Figure 2 shown.

[0028] (3) 1.6 g (1.0 mmol) of bromoethoxy-substituted brominated columnar aromatic hydrocarbon and 0.9 g (10 mmol) of 2-aminoimidazole were dissolved in 50 ml of acetone-acetonitrile mixed solvent (volume ratio 1:1), 0.1 g of diethylamine was used as a catalyst, and the reaction was carried out at 85 °C for 12 hours. After the reaction was completed, it was directly subjected to reduced pressure distillation to obtain 2-aminoimidazole modified columnar aromatic hydrocarbon. Then 0.2 g of 2-aminoimidazole modified columnar aromatic hydrocarbon was dissolved in 80 ml of acetone-acetonitrile solution (volume ratio 1:1), 2.5 g of porous silica was dispersed in the solution, and the precipitation was impregnated at normal pressure and temperature for 12 hours and then dried to complete one impregnation. The impregnation process was repeated twice, and a total of 0.6 g of 2-aminoimidazole modified columnar aromatic hydrocarbon was used. Finally, the obtained solid material was dried, calcined, and sieved with 20-40 mesh to obtain imidazole columnar aromatic hydrocarbon impregnated silicon carbon dioxide adsorption material.

Claims

1. A method for preparing an imidazole column aromatic hydrocarbon impregnated silicon carbon dioxide adsorbent material, comprising the following steps: (1) 1,4-benzenediol and ethylene dibromide are subjected to reflux reaction in the presence of potassium hydroxide and potassium iodide as catalysts and acetonitrile as solvent at 75-80°C for 20-24 hours. The solid obtained after vacuum distillation is purified by column chromatography to obtain 1,4-bis(2-bromoethoxy)benzene; (2) Using 1, 4-bis(2-bromoethoxy)benzene as a structural module, boron trifluoride ethyl ether as a catalyst, polyformaldehyde as a bridging polymerization agent, and dry 1, 2-dichloromethane as a reaction solvent, the reaction was carried out at room temperature for 1.5 to 2.0 hours in a nitrogen atmosphere. After the reaction was completed, methanol was poured into the reaction to terminate the reaction, and the reaction was extracted with water and a saturated sodium bicarbonate solution. The organic phase was dried over anhydrous magnesium sulfate, and the solid obtained after vacuum distillation was subjected to column chromatography to obtain a brominated columnar aromatic hydrocarbon substituted with bromoethoxy; (3) The brominated pillar aromatic hydrocarbon substituted with bromoethoxy and 2-aminoimidazole are dissolved in a mixed solvent of acetone-acetonitrile, diethylamine is used as a catalyst, and the reaction is carried out at 85-90 °C for 10-12 hours. After the reaction is completed, the reaction is directly subjected to reduced pressure distillation to obtain 2-aminoimidazole-modified pillar aromatic hydrocarbon; (4) Dissolve 2-aminoimidazole modified column aromatic hydrocarbon in acetone-acetonitrile solution, disperse porous silica in the solution, immerse for 10 to 12 hours at room temperature and pressure, and then dry to complete the immersion. Repeat the immersion process twice. Finally, the obtained solid material is dried, calcined, and sieved to obtain imidazole column aromatic hydrocarbon impregnated silicon carbon dioxide adsorption material.

2. The method for preparing the imidazole column aromatic impregnated silicon carbon dioxide adsorbent material according to claim 1, characterized in that: In step (1), the molar ratio of 1,4-benzenediol to ethylene dibromide is 1:2-1:3; the molar ratio of 1,4-benzenediol to potassium hydroxide is 1:1-1:1.5; and the molar ratio of 1,4-benzenediol to potassium iodide is 1:2-1:2.

5.

3. The method for preparing the imidazole column aromatic impregnated silicon carbon dioxide adsorbent material according to claim 1, characterized in that: In step (2), the mass ratio of boron trifluoride etherate to 1,4-bis(2-bromoethoxy)benzene is 1:1-1:1.5; the mass ratio of 1,4-bis(2-bromoethoxy)benzene to paraformaldehyde is 1:0.5-1:1.

0.

4. The method for preparing the imidazole column aromatic hydrocarbon impregnated silicon carbon dioxide adsorbent material according to claim 1, characterized in that: In step (3), the molar ratio of the brominated columnar aromatic hydrocarbon substituted with bromoethoxy to 2-aminoimidazole is 1:10 to 1:

15.

5. The method for preparing the imidazole column aromatics impregnated silicon carbon dioxide adsorbent material according to claim 1, characterized in that: In step (3), the acetone-acetonitrile mixed solvent has a volume ratio of acetone to acetonitrile of 1:

1.

6. The method for preparing the imidazole column aromatics impregnated silicon carbon dioxide adsorbent material according to claim 1, characterized in that: In step (4), the mass concentration of 2-aminoimidazole-modified pillar aromatic hydrocarbon in the acetone-acetonitrile solution is 30% to 40%; and the mass ratio of 2-aminoimidazole-modified pillar aromatic hydrocarbon to porous silica is 1:3 to 1:

5.

7. The method for preparing the imidazole column aromatics impregnated silicon carbon dioxide adsorbent material according to claim 1, characterized in that: In step (4), in the acetone-acetonitrile solution, the volume ratio of acetone to acetonitrile is 1:

1.

8. Use of the imidazole column aromatic hydrocarbon-impregnated silicon carbon dioxide adsorption material prepared by the method according to claim 1 in the selective adsorption of carbon dioxide.

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