Preparation and application of direct air capture carbon dioxide adsorbent with flexibility and electrothermal properties

Abstract

The application relates to a preparation and application of a direct air capture carbon dioxide adsorbent with flexibility and electrothermal characteristics. The direct air capture carbon dioxide adsorbent with flexibility and electrothermal characteristics prepared in the application selects a cheap and easily obtained filter paper as a raw material, can directly capture low-concentration carbon dioxide from air, has a carbon dioxide adsorption capacity of 0.91 mmol / g, and can realize rapid adsorbent regeneration under direct current voltage by utilizing the excellent electrothermal performance of the adsorbent. The average electrothermal temperature can reach 200 DEG C in 20s under a direct current voltage of 30V and is maintained stable, problems such as the disturbance of water in the high-temperature steam regeneration process and the excessively high regeneration energy consumption are avoided, and the carbon footprint can be reduced as a whole by using renewable electric energy. The direct air capture carbon dioxide adsorbent has the characteristics of high adsorption capacity, cycle stability, low cost, low regeneration cost, large-scale preparation and the like, and has a good application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of carbon capture, and particularly relates to preparation and application of a direct air capture carbon dioxide adsorbent with flexibility and electrothermal properties. BACKGROUND

[0002] Since the industrial revolution, the rising concentration of carbon dioxide in the atmosphere has led to global warming. The resulting problems such as land desertification, glacier melting, tropical rainforest disappearance, and sea level rise are becoming increasingly serious. Carbon capture and storage is a key problem that needs to be solved by all mankind. According to the IPCC Special Report on Global Warming of 1.5°C, the concentration of carbon dioxide in the atmosphere will continue to rise in the short term. Therefore, the importance of negative carbon technology research is more prominent. Direct air capture (DAC) is a solution to mobile emission sources and the stock of carbon dioxide in the atmosphere, and is a key technology for solving global warming.

[0003] The biggest challenge for direct air capture technology is to selectively remove carbon dioxide with a concentration of only 400 ppm in air, which requires the adsorbent to have high adsorption capacity, excellent selectivity and low regeneration energy consumption. Eloy et al. mentioned in Direct Capture of CO2 from Ambient Air that the related research on DAC adsorbents focuses on the research of solid supported amine materials. For example, Jones et al. in Amine-Tethered Solid Adsorbents Coupling High Adsorption Capacity and Regenerability for CO2 Capture from Ambient Air and Mesoporous Alumina Supported Amines as Potential Steam-Stable Adsorbents for Capturing CO2 from Simulated Flue Gas and Ambient Air used grafting, impregnation and other methods to immobilize amines on the surface of silica solids to achieve the absorption of carbon dioxide from simulated air. Wang Tao et al. in patent application number CN202210472743.3 Amine Metal-Organic Framework Adsorbent for Absorbing Carbon Dioxide in Air and Its Preparation and Application, grafted amine compounds to metal-organic frameworks for absorbing carbon dioxide in air. A. Goertzer et al. in patent application number CN201480074687.1 Regenerable adsorbent of modified amine on nanostructured carrier, used modified polyamine and nanostructured solid carrier to achieve high selective carbon dioxide separation and multiple adsorption-desorption cycles in air. Zhao Hongyu et al. in patent application number CN201611039491.6 Preparation method and application of carbon-based carbon dioxide adsorbent, constructed a carbon-based adsorbent with strong metal ions, which has excellent adsorption performance under low pressure conditions. Zhang Rong et al. in patent application number CN202210068407.2 Melamine resin-based nitrogen-doped mesoporous carbon dioxide adsorbent, used the high specific surface area and high porosity of nitrogen-doped mesoporous carbon material to improve the carbon dioxide capture performance of mesoporous carbon material.

[0004] We noticed that the adsorbent materials for direct air capture of carbon dioxide using amine immobilization methods are being continuously developed, but the mainstream high-temperature steam regeneration method has high energy consumption, and the high production and processing costs of related adsorbents (such as MOF, metal oxide, cellulose, etc.) further limit the popularization and application of the technology. Using the electrothermal properties of carbon materials, the regeneration energy consumption of the material is greatly reduced, but there is no related report on the electrothermal properties of carbon materials, which is a research gap in the field. SUMMARY

[0005] The present application aims at the defects existing in the adsorbent design of the existing direct air capture carbon dioxide technology, and provides a direct air capture carbon dioxide adsorbent with flexibility and electrothermal characteristics and preparation and application thereof.

[0006] The technical scheme of the present application is as follows:

[0007] The preparation and application of a direct air capture carbon dioxide adsorbent with flexibility and electrothermal characteristics use filter paper as a raw material, and the filter paper is subjected to freeze drying, immersion in carbon tube dispersion liquid and polyethyleneimine solution, so as to form a direct air capture carbon dioxide adsorbent with flexibility and electrothermal characteristics.

[0008] The preparation method of a direct air capture carbon dioxide adsorbent with flexibility and electrothermal characteristics comprises the following steps:

[0009] In the first step, phase change hole expansion, the filter paper is wetted in deionized water for 1-2 min, and then subjected to freeze drying under vacuum for 36-48 h, so as to obtain filter paper with greater porosity and micro-pore size;

[0010] In the second step, conductive layer coating, multi-walled carbon nanotubes are added to a sodium cholate solution with a concentration of 10 mg / mL and shaken uniformly, wherein the addition amount of the multi-walled carbon nanotubes is 5-10 mg / mL; the mixed solution is first subjected to bath ultrasonic for 5 min, and then subjected to tip ultrasonic for 5 min; after the bath ultrasonic for 30 min and the tip ultrasonic for 5 min, the obtained dispersion liquid is subjected to high-speed centrifugation to remove the un-exfoliated multi-walled carbon nanotubes, and the high-speed centrifugation obtains a high-concentration multi-walled carbon nanotube dispersion liquid; the filter paper with greater porosity is cut and immersed in the multi-walled carbon nanotube dispersion liquid for 30-60 s, and then dried in an oven at 80-100℃ for 1-2 h; the immersion-drying process is repeated 1-5 times to obtain a sample with a multi-walled carbon nanotube carbon tube loading amount of 5%-10%.

[0011] In the third step, amine functionalization, the sample obtained in the second step is immersed in a polyethyleneimine aqueous solution with a mass fraction of 5%-10% and a molecular weight of 600-1800, and then dried at a temperature of 80-100℃ for 1-2 h after 30 s; the immersion-drying process is repeated 1-3 times to obtain a sample with a loading amount of 10%-30%.

[0012] The obtained sample is heated in high-purity nitrogen at 90-110 DEG C for 120 min to remove the carbon dioxide adsorbed by the sample; after the heating process is completed and the sample is sufficiently wetted with humid air, air is introduced at room temperature to test the adsorption performance. After the sample is saturated, the sample is subjected to electric heating adsorbent regeneration under a direct current voltage of 5V-30V. The adsorbent temperature is maintained at 90-110 DEG C during the regeneration.

[0013] The present application has the following advantages: the filter paper is used as a raw material, which is cheap and easy to obtain; the flexible carbon dioxide adsorbent with high porosity, high specific surface area, stable mechanical strength and electrothermal properties can be mass-produced by freeze-drying, impregnating multi-walled carbon nanotube dispersion and polyethyleneimine solution. The density and air resistance of the adsorbent formed by the filter paper are much lower than those of the traditional packed bed adsorbent due to the low density and high porosity of the filter paper. The carbon paper substrate introduces an electrothermal regeneration function, which avoids the energy-consuming and low-efficiency steam regeneration adsorbent process, and improves the integration and efficiency of the adsorption equipment. The adsorbent has the characteristics of high adsorption capacity, stable cycle, low cost, low regeneration cost, mass production, etc. BRIEF DESCRIPTION OF DRAWINGS

[0014] Figure 1 is the resistance value change of the sample impregnated with multi-walled carbon tube dispersion for different times.

[0015] Figure 2 is the electrothermal performance temperature curve of the sample impregnated with carbon tube for five times under different voltages.

[0016] Figure 3 is the carbon dioxide adsorption performance of the sample impregnated with carbon tube for five times and impregnated with polyethyleneimine aqueous solution for different times. DETAILED DESCRIPTION

[0017] The present application will be further described in detail below in combination with specific implementation examples, but is not limited to the following examples.

[0018] Example 1

[0019] A flexible and electrothermal carbon dioxide adsorbent with direct air capture and its preparation and application, comprising the following steps:

[0020] S1, phase change hole expansion

[0021] The filter paper is wetted in deionized water for 1 min, and then subjected to freeze-drying under vacuum for 36 h to obtain filter paper with larger porosity and micro-pore size.

[0022] S2, conductive layer coating

[0023] For multi-walled carbon nanotube dispersion, the preparation process is as follows: multi-walled carbon nanotubes are added to a sodium cholate solution with a concentration of 10 mg / mL and shaken uniformly, wherein the added amount of multi-walled carbon nanotubes is 5 mg / mL. The mixed solution is first subjected to bath ultrasonic for 5 min, and then subjected to tip ultrasonic for 5 min. After being subjected to bath ultrasonic for 30 min and tip ultrasonic for 5 min in turn, the obtained dispersion is subjected to high-speed centrifugation to remove un-exfoliated multi-walled carbon nanotubes, and a high-concentration multi-walled carbon nanotube dispersion is obtained after centrifugation. A filter paper with a larger porosity is cut and immersed in a multi-walled carbon nanotube dispersion with a concentration of 1 mg / mL for 30 s, and then dried in an oven at 80°C for 1-2 h. The immersion-drying process is repeated 1-5 times to obtain a sample with a multi-walled carbon nanotube loading of 5%.

[0024] S3, amine functionalization

[0025] The sample after the carbon tube immersion is immersed in a polyethyleneimine aqueous solution with a mass fraction of 5% and a molecular weight of 1800. After 30 s, drying is performed at a temperature of 80°C for 1 h. The immersion-drying process is repeated 3 times to obtain a sample with a loading of 30%.

[0026] S4, carbon dioxide capture and electrothermal adsorbent regeneration

[0027] The obtained sample is heated in high-purity nitrogen at 90°C for 120 min to remove the carbon dioxide adsorbed by the sample; after the heating process is completed and the sample is fully wetted with humid air, air is introduced at room temperature for adsorption performance testing. After the sample is saturated, the sample is subjected to electrothermal adsorbent regeneration under a direct current voltage of 20 V. The electrothermal temperature of the adsorbent is maintained at 110°C during the process.

[0028] Figure 1 The change in the resistivity of the sample after 1-5 times of immersion of the multi-walled carbon tube dispersion is shown. The conductivity of the sample can be intuitively reflected by the resistivity of the sample, and the loading of the multi-walled carbon tube in the sample increases as the number of immersion times increases. The resistivity of the sample decreases exponentially from 104.7 Ω / cm after 1 time of immersion to 10.2 Ω / cm after 5 times of immersion. The improvement in the conductivity of the sample shows that immersion is an effective means for the filter paper to load multi-walled carbon tubes.

[0029] Example 2

[0030] A direct air capture carbon dioxide adsorbent with flexibility and electrothermal properties, and a preparation and application thereof, comprising the following steps:

[0031] S1, phase change pore expansion

[0032] The filter paper is wetted in deionized water for 2 min, and then subjected to freeze-drying under vacuum for 36 h to obtain a filter paper with a larger porosity and micro-pore size.

[0033] S2, conductive layer coating

[0034] For multi-walled carbon nanotube dispersion, the preparation process is as follows: multi-walled carbon nanotubes are added to a sodium cholate solution with a concentration of 10 mg / mL and shaken uniformly, wherein the added amount of multi-walled carbon nanotubes is 5 mg / mL. The mixed solution is first subjected to bath ultrasonic for 5 min, and then subjected to tip ultrasonic for 5 min. After sequentially subjected to bath ultrasonic for 30 min and tip ultrasonic for 5 min, the obtained dispersion is subjected to high-speed centrifugation to remove un-exfoliated multi-walled carbon nanotubes, and a high-concentration multi-walled carbon nanotube dispersion is obtained after centrifugation. A filter paper with a larger porosity is cut and immersed in a multi-walled carbon nanotube dispersion with a concentration of 1 mg / mL for 30 s, and then dried in an oven at 80°C for 1-2 h. The immersion-drying process is repeated 5 times to obtain a sample with a multi-walled carbon nanotube loading of 10%.

[0035] S3, amine functionalization

[0036] The sample after the carbon tube immersion is immersed in a polyethyleneimine aqueous solution with a mass fraction of 10% and a molecular weight of 1800. After 30 s, drying is performed at a temperature of 100°C for 1 h. The immersion-drying process is repeated once to obtain a sample with a loading of 30%.

[0037] S4, carbon dioxide capture and electrothermal adsorbent regeneration

[0038] The obtained sample is heated in high-purity nitrogen at 110°C for 120 min to remove the carbon dioxide adsorbed by the sample; after the heating process is completed and the sample is fully wetted with humid air, air is introduced at room temperature for adsorption performance testing. After the sample is saturated, the sample is subjected to electrothermal adsorbent regeneration under a direct current voltage of 5V-30V. During the process, the electrothermal temperature of the adsorbent is maintained at 90°C.

[0039] Figure 2 The electrothermal performance of the sample immersed in the multi-walled carbon tube dispersion for 5 times is demonstrated under different voltages. From the curve of the average electrothermal temperature over time, it can be seen that the sample can be rapidly heated and maintained stable under different sizes of direct current voltage. Taking a direct current voltage of 30V as an example, after being connected to the power supply, the average electrothermal temperature of the sample rapidly rises from room temperature to about 210°C within 20 s, and can be maintained stable for a long time. As the voltage decreases, the average electrothermal temperature of the sample decreases regularly. This confirms that the electrothermal temperature of the sample can be adjusted in real time by adjusting the size of the voltage. At the same time, the highest electrothermal temperature of the sample is 210°C, which indicates that the electrothermal performance of the sample fully meets the sample regeneration temperature requirement, and the regeneration of the carbon dioxide adsorbent can be realized according to the actual application occasion.

[0040] Example 3

[0041] The application discloses a direct air capture carbon dioxide adsorbent with flexibility and electrothermal characteristics, and preparation and application thereof.

[0042] S1, phase change reaming

[0043] After the filter paper is wetted in deionized water for 1 min, freeze-drying is performed under vacuum for 36 h to obtain the filter paper with larger porosity and micropore size.

[0044] S2, conductive layer coating

[0045] For the multi-walled carbon nanotube dispersion liquid, the preparation process is as follows: the multi-walled carbon nanotubes are added into a sodium cholate solution with a concentration of 10 mg / mL and shaken uniformly, wherein the addition amount of the multi-walled carbon nanotubes is 5 mg / mL. The mixed solution is first subjected to bath ultrasonic for 5 min, and then subjected to tip ultrasonic for 5 min. After the bath ultrasonic for 30 min and the tip ultrasonic for 5 min are sequentially performed, the obtained dispersion liquid is subjected to high-speed centrifugation to remove the un-exfoliated multi-walled carbon nanotubes, and the high-concentration multi-walled carbon nanotube dispersion liquid is obtained after centrifugation. The filter paper with larger porosity is cut and immersed in the multi-walled carbon nanotube dispersion liquid with a concentration of 1 mg / mL for 60 s, and then dried in an oven at 100 DEG C for 1-2 h. The immersion-drying process is repeated for 5 times to obtain a sample with a multi-walled carbon nanotube loading amount of 10%.

[0046] S3, amine functionalization

[0047] The sample after the carbon tube immersion is immersed in a polyethyleneimine aqueous solution with a mass fraction of 10% and a molecular weight of 600. After 30 s, drying is performed at a temperature of 80 DEG C for 2 h. The immersion-drying process is repeated for 1-3 times to obtain a sample with a loading amount of 30%.

[0048] S4, carbon dioxide capture and electrothermal adsorbent regeneration

[0049] The obtained sample is heated in high-purity nitrogen at 90 DEG C for 120 min to remove the carbon dioxide adsorbed by the sample; after the heating process is completed and the sample is sufficiently wetted with humid air, air is introduced at a flow rate of 100 ml / min at room temperature to test the adsorption performance. After the sample is saturated, the sample is subjected to electrothermal adsorbent regeneration under a direct current voltage of 20 V. During the process, the electrothermal temperature of the adsorbent is maintained at 110 DEG C.

[0050] Figure 3The carbon nanotube samples were immersed in the polyethyleneimine solution for different times, and the carbon dioxide adsorption performance of the samples was tested. As shown in the figure, the sample immersed for 1 time already has a carbon dioxide capture capacity of 0.52 mmol / g, and the capture capacities of the samples immersed for 2 and 3 times are 0.91 mmol / g and 0.75 mmol / g respectively. Within a certain range, the increase of the amine loading can improve the capture capacity of the adsorbent. However, with the further increase of the amine loading, the decrease of the specific surface area of the material will reduce the contact area between the air and the adsorbent, resulting in the decrease of the amine efficiency and the adsorption performance.

[0051] Example 4

[0052] A direct air capture carbon dioxide adsorbent with flexibility and electrothermal properties, and a preparation and application thereof, comprising the following steps:

[0053] S1, phase change reaming

[0054] After the filter paper is wetted in deionized water for 2 min, it is subjected to freeze-drying under vacuum for 48 h to obtain a filter paper with larger porosity and micro-pore size.

[0055] S2, conductive layer coating

[0056] For the multi-walled carbon nanotube dispersion, the preparation process is as follows: the multi-walled carbon nanotube is added to a sodium cholate solution with a concentration of 10 mg / mL and shaken uniformly, wherein the addition amount of the multi-walled carbon nanotube is 10 mg / mL. The mixed solution is first subjected to bath ultrasonic for 5 min, and then subjected to tip ultrasonic for 5 min. After sequentially subjected to bath ultrasonic for 30 min and tip ultrasonic for 5 min, the obtained dispersion is subjected to high-speed centrifugation to remove the un-exfoliated multi-walled carbon nanotube, and a high-concentration multi-walled carbon nanotube dispersion is obtained after centrifugation. The filter paper with larger porosity is cut and immersed in a multi-walled carbon nanotube dispersion with a concentration of 2 mg / mL for 30 s, and then dried in an oven at 100°C for 1-2 h. The immersion-drying process is repeated 4 times to obtain a sample with a multi-walled carbon nanotube loading of 8%.

[0057] S3, amine functionalization

[0058] The sample after the carbon nanotube immersion is immersed in a polyethyleneimine aqueous solution with a mass fraction of 5% and a molecular weight of 1800. After 30 s, drying is performed at a temperature of 80°C for 2 h. The immersion-drying process is repeated 2 times to obtain a sample with a loading of 20%.

[0059] S4, carbon dioxide capture and electrothermal adsorbent regeneration

[0060] The obtained sample was heated in high-purity nitrogen at 90°C for 120 min to remove the carbon dioxide adsorbed by the sample; after the heating process was completed and the sample was sufficiently wetted with humid air, the air adsorption performance test was carried out at room temperature with the air flowing at 100 ml / min. After the sample was saturated with adsorption, the electric heating adsorbent regeneration was carried out at a direct current voltage of 25 V. During the process, the electric heating temperature of the adsorbent was maintained at 110°C.

[0061] Example 5

[0062] A direct air capture carbon dioxide adsorbent with flexibility and electric heating characteristics, and preparation and application thereof, comprising the following steps:

[0063] S1, phase change hole expansion

[0064] After the filter paper was wetted in deionized water for 1 min, it was subjected to freeze-drying under vacuum for 48 h to obtain a filter paper with larger porosity and micro-pore size.

[0065] S2, conductive layer coating

[0066] For the multi-walled carbon nanotube dispersion solution, the preparation process is as follows: multi-walled carbon nanotubes are added to a sodium cholate solution with a concentration of 10 mg / mL and shaken uniformly, wherein the addition amount of multi-walled carbon nanotubes is 10 mg / mL. The mixed solution is first subjected to bath ultrasonic for 5 min, and then subjected to tip ultrasonic for 5 min. After sequentially subjected to bath ultrasonic for 30 min and tip ultrasonic for 5 min, the obtained dispersion solution is subjected to high-speed centrifugation to remove un-exfoliated multi-walled carbon nanotubes, and a high-concentration multi-walled carbon nanotube dispersion solution is obtained after centrifugation. The filter paper with larger porosity is cut and immersed in a multi-walled carbon nanotube dispersion solution with a concentration of 2 mg / mL for 60 s, and then dried in an oven at 100°C for 1-2 h. The immersion-drying process is repeated 5 times to obtain a sample with a multi-walled carbon nanotube loading of 10%.

[0067] S3, amine functionalization

[0068] The sample after immersion of carbon nanotubes is immersed in a polyethyleneimine aqueous solution with a mass fraction of 5% and a molecular weight of 600. After 30 s, drying is carried out at a temperature of 100°C for 2 h. The immersion-drying process is repeated once to obtain a sample with a loading of 10%.

[0069] S4, carbon dioxide capture and electric heating adsorbent regeneration

[0070] The obtained sample was heated in high purity nitrogen at 90°C for 120 minutes to remove the carbon dioxide adsorbed by the sample; after the heating process was completed and the sample was sufficiently humidified with humid air, the adsorption performance test was carried out by passing air at a rate of 100 ml / min at room temperature. After the sample was saturated with adsorption, the sample was subjected to electrothermal adsorbent regeneration under a direct current voltage of 30 V. The electrothermal temperature of the adsorbent was maintained at 110°C during the process.

[0071] The above description is only a description of the preferred embodiments of the present application and is not intended to limit the scope of the present application. Those skilled in the art can make various modifications and variations to the present application without departing from the spirit and scope of the present application. Thus, if these modifications and variations of the present application fall within the scope of the claims of the present application and equivalent technologies thereof, the present application is intended to include these modifications and variations.

Claims

1. A method for preparing a direct air capture carbon dioxide adsorbent having flexible, electrocaloric properties, characterized in that, Comprising the following steps: The first step, phase transition hole expansion: after the filter paper is wetted in deionized water for 1-2 min, freeze-drying is carried out under vacuum for 36-48 h to obtain filter paper with larger porosity and micro-pore size; The second step, conductive layer coating: the multi-walled carbon nanotubes are added to the sodium cholate solution and shaken uniformly; the mixed solution is first subjected to bath ultrasonic for 5 min, and then subjected to tip ultrasonic for 5 min; after being subjected to bath ultrasonic for 30 min and tip ultrasonic for 5 min in turn, the obtained dispersion liquid is subjected to high-speed centrifugation to remove the un-exfoliated multi-walled carbon nanotubes, and a high-concentration multi-walled carbon nanotube dispersion liquid is obtained after centrifugation; the filter paper treated in the first step is cut and immersed in the multi-walled carbon nanotube dispersion liquid for 30-60 s, and then dried; the immersion-drying process is repeated 1-5 times to obtain a sample with a multi-walled carbon nanotube carbon nanotube loading of 5%-10%; The third step, amine functionalization: the sample obtained in the second step is immersed in a polyethyleneimine aqueous solution with a mass fraction of 5%-10% and a molecular weight of 600-1800, and dried at a temperature of 80-100℃ for 1-2 h after 30 s; the immersion-drying process is repeated 1-3 times to obtain a sample with a loading of 10%-30%, which is a direct air capture carbon dioxide adsorbent with flexibility and electrothermal properties.

2. The production method according to claim 1, characterized by, The filter paper is wetted in deionized water for 1-2 min, and then freeze-dried under vacuum for 36-48 h.

3. The production method according to claim 1, characterized by, The concentration of the sodium cholate solution is 10 mg / mL, and the addition amount of the multi-walled carbon nanotubes is 5-10 mg / mL.

4. The method of claim 1, wherein, In the second and third steps, the drying conditions are: 80-100℃ drying for 1-2 h.

5. The preparation method according to claim 1, characterized in that, The power of the two bath ultrasonic is 80 W, and the parameters of the two tip ultrasonic are set as 25% power, 2 s on and 2 s off.

6. Use of the direct air capture carbon dioxide adsorbent having flexibility and electrocaloric properties obtained by the production method according to any one of claims 1 to 5, characterized in that, The carbon dioxide adsorbent is heated in nitrogen at 90-110℃ for 120 min to remove the carbon dioxide adsorbed in the carbon dioxide adsorbent; after the heating process is completed and the carbon dioxide adsorbent is fully wetted with humid air, air is introduced at room temperature to test the adsorption performance.

7. Use according to claim 6, characterized in that, After the carbon dioxide adsorbent is saturated, the carbon dioxide adsorbent is subjected to electrothermal adsorbent regeneration under a direct current voltage of 5 V-30 V, and the electrothermal temperature of the carbon dioxide adsorbent is maintained at 90-110℃ during the regeneration.

Images