Preparation and application of an amine-based aromatic carbon dioxide selective adsorbent

Abstract

The present invention provides a preparation of an amino-based pillar aromatic carbon dioxide selective adsorbent and its use for selective adsorption and separation of carbon dioxide from methane and nitrogen. The present invention uses fully brominated pillar aromatics to bond aminopropyl porous silicon and further react with diethylenetriamine for halogenation, efficiently preparing a diethylenetriamine-grafted pillar aromatic modified porous silicon carbon dioxide selective adsorbent, and carries out a carbon dioxide adsorption process and a carbon dioxide / methane, carbon dioxide / nitrogen selective adsorption and separation process to study its carbon dioxide saturation adsorption capacity, selectivity, repeatability and practical applicability, proving that the adsorbent has good separation potential for carbon dioxide and nitrogen, carbon dioxide and methane, and has good reusability, and is expected to be applied to the efficient capture and storage of carbon dioxide in industrial flue gas or mixed gas.

Description

Technical Field

[0001] The present invention relates to the field of "dual carbon" module carbon dioxide capture and storage in energy and environment, and specifically to the preparation of an amino-based column aromatic carbon dioxide selective adsorbent and the evaluation of carbon dioxide / methane and carbon dioxide / nitrogen selective adsorption and separation performance. Background Art

[0002] Excessive emissions of carbon dioxide from the combustion of fossil fuels are the main cause of the greenhouse effect, but carbon dioxide is also a very important carbon resource in the preparation of fine chemicals, beverage additives and other industries. Recent studies have confirmed that carbon dioxide capture and storage is a potential method for carbon emission reduction. To date, a variety of capture and adsorption technologies and new materials have been studied for capturing carbon dioxide. Among them, solid adsorbents are considered to be the most promising adsorbents in capture materials due to their simple preparation, good repeatability and stability. However, these adsorbents have the disadvantages of poor selectivity or low adsorption capacity. Therefore, it is crucial to develop new solid adsorbents with high efficiency in capturing carbon dioxide.

[0003] In order to explore the actual adsorption and separation performance of solid amine adsorbents, improving the CO2 capture capacity of adsorbents and the selectivity of CO2 to methane and nitrogen, as well as stability and regenerability are issues of great concern in the development of adsorbents. In recent years, solid amine adsorbents prepared by grafting or impregnating porous silica with organic amines have attracted widespread attention due to their high selectivity, easy regeneration and high CO2 capture capacity. The gas adsorption capacity and selectivity of porous solid amine adsorbents may depend on their specific surface area, pore volume and porosity, as well as the interaction between gas molecules and the active sites of the main skeleton groups. Among these factors, pore volume and active sites are crucial to the adsorption capacity, especially for selective adsorption. However, how to optimize the design scheme to simultaneously achieve high adsorption capacity and high selectivity remains a great challenge. Especially in the separation of CO2 from nitrogen and methane, it is difficult to perform selective adsorption due to similar sizes and interactions between molecules. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing an amino-based pillar aromatic carbon dioxide selective adsorbent.

[0005] Another object of the present invention is to provide an application of the adsorbent in selectively adsorbing and separating carbon dioxide in adsorbing carbon dioxide, in a mixture of carbon dioxide and methane, or in a mixture of carbon dioxide and nitrogen.

[0006] 1. Preparation of amino-based aromatic carbon dioxide selective adsorbent

[0007] (1) Preparation of perbrominated pillar aromatics: Under air atmosphere and room temperature, 1,4-bis(2-bromoethoxy)benzene was dissolved in anhydrous 1,2-dichloroethane solution, and polyformaldehyde was added as polymerization reagent and boron trifluoride etherate as catalyst. The mixture was stirred at room temperature for 1.0-1.2 hours. After the reaction, the mixture was added to methanol to quench the reaction. The solid obtained after filtration was washed with water and saturated sodium bicarbonate solution, and then the organic layer was dried with anhydrous magnesium sulfate. The organic solvent was removed in vacuo and purified by column chromatography to obtain perbrominated pillar aromatics. The mass ratio of polyformaldehyde to 1,4-bis(2-bromoethoxy)benzene was 0.3:1-0.4:1; the mass ratio of polyformaldehyde to boron trifluoride etherate was 0.5:1-0.6:1. The synthetic route is as follows:

[0008]

[0009] (2) Preparation of porous silica powder material modified by diethylenetriamine grafted columnar aromatics: Disperse aminopropyl silica gel in anhydrous toluene, add perbrominated columnar aromatics obtained in step (1), diethylenetriamine and catalyst triethylamine, reflux at 95-100°C for 46-48h, and filter to obtain a light yellow filter cake after the reaction is completed. After washing with acetonitrile, ethanol and methanol, vacuum dry to obtain a porous silicon powder material modified by diethylenetriamine grafted columnar aromatics. Among them, the mass ratio of perbrominated columnar aromatics to aminopropyl silica gel is 0.3:1-0.5:1; the mass ratio of perbrominated columnar aromatics to diethylenetriamine is 0.8:1-0.9:1; the mass ratio of triethylamine to perbrominated columnar aromatics is 0.06:1-0.08:1. The synthesis route of the porous silicon powder material modified by diethylenetriamine grafted columnar aromatics is as follows:

[0010]

[0011] (3) Preparation of amino-based aromatic carbon dioxide selective adsorbent: Add diethylenetriamine grafted aromatic carbon dioxide modified porous silicon powder material and silica sol into 8-10 ml of water, stir for 25-30 minutes, remove the solvent under reduced pressure, and dry the obtained material under vacuum at 50-55 degrees Celsius and pass through a 30-mesh sieve to obtain amino-based aromatic carbon dioxide selective adsorbent particles. The mass ratio of silica sol to diethylenetriamine grafted aromatic carbon dioxide modified porous silicon powder material is 0.02:1-0.08:1.

[0012] 2. Characterization of amine-based aromatic carbon dioxide selective adsorbent

[0013] 1. Scanning electron microscope

[0014] The morphology of the amino-pillar aromatic carbon dioxide selective adsorbent was characterized by scanning electron microscopy. Figure 1As shown, from the scanning electron microscope image magnified 2000 times, it can be seen that the adsorbent presents a rough surface silica particle accumulation agglomeration morphology structure, and these pore structures are more conducive to high-capacity adsorption and selective separation of carbon dioxide.

[0015] 2. Infrared spectroscopy

[0016] The infrared spectrum of the adsorbent is shown in Figure 2 As shown in the figure, the increased intensity of the absorption bands at 3439 and 1638 wavenumbers is attributed to the stretching vibration and bending vibration of the N−H bond. The characteristic absorption peaks at 2933 and 2856 wavenumbers belong to the symmetric stretching and asymmetric stretching vibration peaks corresponding to the C−H bond, respectively. The peak at 1506 wavenumber corresponds to the symmetric vibration absorption of the N−H bond. The wavenumbers at 1095, 807 and 466 wavenumbers are the characteristic vibration peaks of the Si−O−Si bond in the porous adsorbent. These data confirm the successful preparation of the amino-based pillar aromatic carbon dioxide selective adsorbent.

[0017] 3. Mercury Intrusion Analysis

[0018] Mercury intrusion porosimetry further confirmed that the total pore volume of the amino-based aromatic carbon dioxide selective adsorbent is 1.66 ml / g, the pore diameter is 77.17 nm, and the porosity reaches 67.73%, providing favorable conditions for the adsorption of carbon dioxide. The macropores formed may be the pores between porous silica in the aggregate granulation, and the mesopores come from porous silica. The specific results of mercury intrusion analysis are as follows: Figure 3 shown.

[0019] 3. Performance evaluation of amine-based aromatic carbon dioxide selective adsorbent

[0020] 1. Flow rate investigation

[0021] In order to investigate the optimal adsorption capacity of the amino-based aromatic carbon dioxide selective adsorbent for carbon dioxide, the breakthrough curves of different gas flow rates were firstly investigated. Figure 4 As shown in the figure, the results show that when the gas flow rate is 10 ml / min, the saturated adsorption capacity of 0.2 g of the amino-based aromatic carbon dioxide selective adsorbent reaches 7.41 mmol / g, but as the gas flow rate further increases, the breakthrough time and saturated adsorption capacity of carbon dioxide decrease. Therefore, the gas flow rate of 10 ml / min is selected as the gas flow rate of the amino-based aromatic carbon dioxide selective adsorbent during the adsorption process.

[0022] 2. Temperature inspection

[0023] Temperature has a significant effect on the saturated adsorption capacity of carbon dioxide. Figure 5The effect of adsorption temperature on the saturated adsorption of carbon dioxide in the range of 30 to 60 degrees Celsius for 0.2 grams of amino-column aromatic carbon dioxide selective adsorbent at a gas flow rate of 10 ml / min was studied. The results show that when the temperature is 40 degrees Celsius, the saturated adsorption of carbon dioxide by the amino-column aromatic carbon dioxide selective adsorbent reaches 8.41 mmol / g, but as the temperature further increases, the adsorption capacity gradually decreases. These results show that the adsorption of carbon dioxide by the amino-column aromatic carbon dioxide selective silicon-based adsorbent may be a kinetically controlled process. Therefore, the amino-column aromatic carbon dioxide selective silicon-based adsorbent is an important factor as a candidate material for carbon dioxide adsorption at 40 degrees Celsius.

[0024] 3. Investigation of carbon dioxide / methane selective adsorption

[0025] In order to further evaluate the actual separation performance of the amino-based aromatic carbon dioxide selective adsorbent, the effect of temperature on the dynamic adsorption performance selectivity of carbon dioxide / methane was evaluated by a breakthrough test. A mixture of carbon dioxide / methane / argon was used with a composition of 5%:5%:90% (the volume fraction of carbon dioxide, methane and argon in the carbon dioxide / methane / argon mixture was 5%, 5% and 90%, respectively), a flow rate of 10 ml / min and a temperature of 30-60 degrees Celsius. During the entire adsorption process, the adsorption time of carbon dioxide was longer than that of methane, indicating that the adsorption capacity of carbon dioxide was strong and the breakthrough time was longer than that of methane. The breakthrough curve clearly shows that the amino-based aromatic carbon dioxide selective adsorbent has good separation potential for carbon dioxide / methane. The results confirmed that the selectivity factor for carbon dioxide / methane was 19 ( Figure 6 ), the adsorbent is expected to be used to capture carbon dioxide in mixed gases or methane components.

[0026] 4. Investigation of carbon dioxide / nitrogen selective adsorption

[0027] In order to further evaluate the simulated industrial flue gas separation performance of the amino-column aromatic carbon dioxide selective adsorbent, the effect of temperature on the dynamic adsorption performance selectivity of carbon dioxide / nitrogen was evaluated by a breakthrough test. A mixture of carbon dioxide / nitrogen / argon was used with a composition of 5%:5%:90% (the volume fraction of carbon dioxide, nitrogen and argon in the carbon dioxide / nitrogen / argon mixture was 5%, 5% and 90%), a flow rate of 10 ml / min and a temperature of 30-60 degrees Celsius. During the entire adsorption process, the adsorption time of carbon dioxide was longer than that of nitrogen, indicating that the adsorption capacity of carbon dioxide was strong and the breakthrough time was longer than that of nitrogen. The breakthrough curve clearly shows that the amino-column aromatic carbon dioxide selective adsorbent has good separation potential for carbon dioxide / nitrogen. The results confirmed that the selectivity factor of carbon dioxide / nitrogen was 14 ( Figure 7), the adsorbent is expected to be used to capture carbon dioxide from industrial flue gas.

[0028] 5. Cycle repeatability test

[0029] As an adsorbent with excellent performance, in addition to large adsorption capacity and strong selective separation, it should also have the advantages of stable adsorption over multiple cycles. During the adsorption process, the amine-based aromatic carbon dioxide selective adsorbent was tested for carbon dioxide cyclic adsorption capacity at an adsorption temperature of 40 degrees Celsius and a desorption temperature of 110 degrees Celsius ( Figure 8 ), the results showed that after 10 cycles of adsorption and desorption, its adsorption capacity for carbon dioxide decreased from 8.2 mmol / g to 7.7 mmol / g, but still maintained a high saturated adsorption capacity of carbon dioxide. The results show that the amino-based pillar aromatic carbon dioxide selective adsorbent can be used for cyclic carbon dioxide adsorption operations.

[0030] In summary, the present invention proposes a preparation technology of an amino-based pillar aromatic carbon dioxide selective adsorbent and a new application of selective adsorption and separation of carbon dioxide, methane and nitrogen. The aminopropyl porous silicon bonded with perbrominated pillar aromatics is further subjected to a halogenation reaction with diethylenetriamine to efficiently prepare an amino-based pillar aromatic carbon dioxide selective adsorbent. The primary and secondary amines of the amino-based pillar aromatic carbon dioxide selective adsorbent have weak nucleophilic properties and can interact with carbon dioxide, and the adsorption of carbon dioxide is better than that of methane and nitrogen. Under 40 degrees Celsius, when the gas flow rate of 5 vol% carbon dioxide is 10 ml / min, the optimal capture amount of the amino-based pillar aromatic carbon dioxide selective adsorbent is 8.2 mmol / g, indicating that the introduction of diethylenetriamine provides amino active sites and the cavity of the pillar aromatics provides capture pores, which promote the adsorption of carbon dioxide. In addition, the obtained amino-based pillar aromatic carbon dioxide selective adsorbent has high carbon dioxide / methane selectivity (19) and carbon dioxide / nitrogen selectivity (14). At the same time, after 10 regeneration cycles, the amino-based aromatic carbon dioxide selective adsorbent can still maintain excellent carbon dioxide adsorption capacity. This adsorbent is expected to be used for the efficient capture and storage of carbon dioxide in mixed gases, methane components or industrial flue gases. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a scanning electron microscope image of the adsorbent of the present invention.

[0032] Figure 2 It is the infrared spectrum of the adsorbent of the present invention.

[0033] Figure 3 This is the mercury injection analysis of the adsorbent of the present invention.

[0034] Figure 4 The effect of gas flow rate on the saturated adsorption capacity of carbon dioxide.

[0035] Figure 5 The effect of adsorption temperature on the saturated adsorption amount of carbon dioxide.

[0036] Figure 6 The adsorbent selectively adsorbs carbon dioxide / methane.

[0037] Figure 7 The adsorbent selectively adsorbs carbon dioxide / nitrogen.

[0038] Figure 8 The saturated adsorption capacity of carbon dioxide was investigated for cyclic adsorption. DETAILED DESCRIPTION

[0039] The technical solution of the present invention is further described in detail below in conjunction with the embodiments, but the protection scope of the present invention is not limited thereto.

[0040] Example

[0041] (1) Preparation of perbrominated columnar aromatics: Under air atmosphere and room temperature, weigh 5.0 g of 1,4-bis(2-bromoethoxy)benzene and dissolve it in 50 ml of anhydrous 1,2-dichloroethane solution, add 1.8 g of paraformaldehyde as a polymerization reagent and 3.0 g of boron trifluoride ether as a catalyst, stir magnetically at room temperature for 1.0 hour, and pour into 80-100 ml of methanol to quench the reaction. After filtration, the obtained solid is washed with 80-100 ml of water and 50-60 ml of saturated sodium bicarbonate solution. Then, the organic layer is dried with 25-30 g of anhydrous magnesium sulfate, and the organic solvent is removed in vacuo. Column chromatography is performed to purify the perbrominated columnar aromatics using a volume ratio of petroleum ether: dichloromethane = 1.5:1~1:1.

[0042] (2) Preparation of diethylenetriamine grafted aromatic column modified porous silicon powder material: Weigh 3.0 g of aminopropyl silica gel and disperse it in 110 ml of anhydrous toluene, add 1.2 g of perbrominated aromatic column obtained in the above steps, 1.4 g of diethylenetriamine and 0.08 g of triethylamine as catalyst, reflux at 95°C for 48 hours, and after the reaction is completed, filter to obtain a light yellow filter cake, wash with 50-60 ml of acetonitrile, 50-60 ml of ethanol and 40-50 ml of methanol, and vacuum dry at 50-55°C for 20-24 hours to obtain diethylenetriamine grafted aromatic column modified porous silicon material.

[0043] (3) Preparation of amine-based aromatic carbon dioxide selective adsorbent: 3.5 g of diethylenetriamine grafted aromatic modified porous silicon material and 0.12 g of silica sol were weighed and dissolved in 10 ml of water. After stirring for 25 minutes, the solvent was removed under reduced pressure. The obtained material was dried and ground through a 30-mesh sieve to obtain a diethylenetriamine grafted aromatic modified porous silicon carbon dioxide selective adsorbent. At 40 degrees Celsius, when the flow rate of 5 vol% carbon dioxide gas was 10 ml / min, the optimal capture capacity of the diethylenetriamine grafted aromatic modified porous silicon carbon dioxide selective adsorbent was 8.2 mmol / g. The carbon dioxide adsorption process and the carbon dioxide / methane and carbon dioxide / nitrogen selective adsorption separation processes were carried out in a fixed bed at normal pressure. The selectivity coefficients of carbon dioxide and methane were 19, and the selectivity coefficients of carbon dioxide and nitrogen were 14.

Claims

1. A method for preparing an amino-based pillar aromatic carbon dioxide selective adsorbent, comprising the following steps: (1) Preparation of perbrominated pillar aromatics: Under air atmosphere and room temperature, 1,4-bis(2-bromoethoxy)benzene was dissolved in anhydrous 1,2-dichloroethane solution, and paraformaldehyde was added as polymerization reagent and boron trifluoride etherate was used as catalyst. The mixture was stirred at room temperature for 1.0-1.2 h. After the reaction, the mixture was added to methanol to quench the reaction. The solid obtained after filtration was washed with water and saturated sodium bicarbonate solution, and the organic layer was then dried over anhydrous magnesium sulfate. The organic solvent was removed in vacuo and purified by column chromatography to obtain perbrominated pillar aromatics. (2) Preparation of porous silica powder material modified by diethylenetriamine grafted aromatic hydrocarbons: aminopropyl silica gel was dispersed in anhydrous toluene, and perbrominated aromatic hydrocarbons, diethylenetriamine and catalyst triethylamine were added. The mixture was refluxed at 95-100°C for 46-48 hours. After the reaction was completed, a light yellow filter cake was obtained by filtration. The cake was washed with acetonitrile, ethanol and methanol, and then vacuum dried to obtain a porous silica powder material modified by diethylenetriamine grafted aromatic hydrocarbons. (3) Preparation of amino-column aromatic carbon dioxide selective adsorbent: Add diethylenetriamine grafted column aromatic hydrocarbon modified porous silica powder material and silica sol into water, stir for 25-30 minutes, and then remove the solvent under reduced pressure. The obtained material is vacuum dried at 50-55 degrees Celsius and passed through a 30-mesh sieve to obtain amino-column aromatic carbon dioxide selective adsorbent particles.

2. The method for preparing the amino-pillar aromatic carbon dioxide selective adsorbent according to claim 1, characterized in that: In step (1), the mass ratio of paraformaldehyde to 1,4-bis(2-bromoethoxy)benzene is 0.3:1-0.4:1; and the mass ratio of paraformaldehyde to boron trifluoride ether is 0.5:1-0.6:

1.

3. The method for preparing the amino-pillar aromatic carbon dioxide selective adsorbent according to claim 1, characterized in that: In step (2), the mass ratio of perbrominated aromatic hydrocarbon to aminopropyl silica gel is 0.3:1 to 0.5:1; The mass ratio of perbrominated aromatic hydrocarbons to diethylenetriamine is 0.8:1~0.9:

1.

4. The method for preparing the amino-pillar aromatic carbon dioxide selective adsorbent according to claim 1, characterized in that: In step (2), the mass ratio of triethylamine to perbrominated aromatic hydrocarbon is 0.06:1 to 0.08:

1.

5. The method for preparing the amino-pillar aromatic carbon dioxide selective adsorbent according to claim 1, characterized in that: In step (3), the mass ratio of silica sol to diethylenetriamine grafted aromatic hydrocarbon modified porous silica powder material is 0.02:1 to 0.08:

1.

6. Use of the amino-pillar aromatic carbon dioxide selective adsorbent prepared by the method according to claim 1 in the adsorption of carbon dioxide.

7. Use of the amino-based pillar aromatic carbon dioxide selective adsorbent prepared by the method according to claim 1 for selectively adsorbing and separating carbon dioxide from a mixture of carbon dioxide and methane.

8. Use of the amino-based pillar aromatic carbon dioxide selective adsorbent prepared by the method according to claim 1 for selectively adsorbing and separating carbon dioxide in a mixture of carbon dioxide and nitrogen.

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