Concentrated ultra-microporous activated carbon fiber material, and preparation method therefor and use thereof

Abstract

The present application belongs to the technical field of adsorption separation, and particularly relates to a concentrated ultra-microporous activated carbon fiber material, and a preparation method therefor and the use thereof. The concentrated ultra-microporous activated carbon fiber material provided by the present application has a concentrated pore diameter, and separates benzene from cyclohexane by means of a screening action generated by the fact that the pore diameter thereof is between the kinetic diameter of benzene and the kinetic diameter of cyclohexane; moreover, benzene is selectively adsorbed by means of the π-π interactions between C=C double bonds on the surface of the concentrated ultra-microporous activated carbon fiber material and the π bonds of benzene. By means of the superposition of pore size screening and surface interactions, the breakthrough points of benzene and cyclohexane are different during the adsorption of benzene and cyclohexane with the concentrated ultra-microporous activated carbon fiber, and a high separation degree can be maintained in a very wide time window, thereby achieving the separation of benzene from cyclohexane. The separation operation is simple, high efficiency and low energy consumption are achieved, energy is saved on, and the material has a high level of stability and a low cost, can be recycled and is suitable for industrial separation.

Description

A concentrated ultra-microporous activated carbon fiber material and its preparation method and application

[0001] This application claims priority to the Chinese patent application filed with the Patent Office of China on February 2, 2024, with application number CN202410145427.4 and invention name “A concentrated ultra-microporous activated carbon fiber material, its preparation method and application”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application belongs to the field of adsorption separation technology, and specifically relates to a concentrated ultra-microporous activated carbon fiber material and its preparation method and application. Background Art

[0003] Cyclohexane is an important chemical raw material, widely used as an organic solvent and a fundamental raw material for the production of nylon-6 and nylon-66. Cyclohexane is typically produced industrially through the hydrogenation of benzene. However, due to incomplete reactions, a certain amount of benzene remains in the product. Therefore, efficient removal of benzene to obtain high-purity cyclohexane is crucial during industrial separation processes. Given the similar physical properties of benzene and cyclohexane molecules, particularly the boiling point difference of only 0.6°C, conventional azeotropic and extractive distillation methods struggle to effectively separate them. Furthermore, these traditional methods are energy-intensive and complex. Furthermore, the use of azeotropic inducers in these methods increases costs and may pose environmental risks. Membrane pervaporation technology also suffers from limited material availability and instability. Given these limitations, there is an urgent need for a feasible and efficient separation method.

[0004] Adsorption separation technology has shown great potential in the separation of benzene and cyclohexane due to its low energy consumption, simple operation process and high separation efficiency. The selection of suitable porous materials is the key to achieving effective adsorption separation. Although new adsorption materials such as Metal-organic Frameworks (MOFs), Covalent Organic Frameworks (COFs) and Porous Molecular Crystals (PMCs) have been studied, they are complex in structure, high in cost and lack stability. The materials have poor acid, alkali and heat resistance and their structures are easily damaged, which limits their practical applications.

[0005] Summary of the Invention

[0006] In view of this, the purpose of this application is to provide a concentrated ultra-microporous activated carbon fiber material, a preparation method and application thereof. The concentrated ultra-microporous activated carbon fiber material prepared in this application has different adsorption penetration points for benzene and cyclohexane, maintains high separation within a very wide time window, realizes the separation of benzene and cyclohexane, has high separation efficiency, high material stability and can be recycled.

[0007] In order to achieve the above objectives, this application provides the following technical solutions:

[0008] The present application provides a concentrated ultra-microporous activated carbon fiber material having a pore size of The pore size distribution concentration is 90-100%.

[0009] Preferably, the diameter of the concentrated ultra-microporous activated carbon fiber material is 0.6-0.82 μm, and the t-plot specific surface area is 555-696 m 2 / g, t-plot pore volume is 0.21~0.26cm 3 / g.

[0010] Preferably, the surface of the concentrated ultramicroporous activated carbon fiber material has C=C double bonds.

[0011] Preferably, the concentrated ultramicroporous activated carbon fiber material has a C mass content of 84-92%, a H mass content of 0.96-1.07%, an O mass content of 4.54-7.14%, and a N mass content of 1.32-3.71%.

[0012] The present application also provides a method for preparing the concentrated ultra-microporous activated carbon fiber material described in the above technical solution, comprising the following steps:

[0013] The resin, organic solvent and additive are mixed, and the obtained suspension is subjected to solid-liquid separation to obtain a supernatant;

[0014] electrospinning the supernatant to prepare a fiber mat, and stabilizing the obtained fiber mat in an air atmosphere to obtain a stabilized fiber mat;

[0015] The stabilized fiber felt is carbonized and activated under a protective atmosphere to obtain a concentrated ultra-microporous activated carbon fiber material;

[0016] The carbonization activation process is as follows: heating to 800-1200° C. at 1-6° C. / min, cooling to 180-200° C. at 3-8° C. / min, and finally naturally cooling to room temperature.

[0017] Preferably, the resin is a phenolic resin; and the auxiliary agent includes polyvinyl pyrrolidone and / or polyvinyl butyral.

[0018] Preferably, the mass ratio of the resin to the auxiliary agent is 5:(1-5).

[0019] Preferably, the electrospinning conditions include: needle size 16-24, receiving distance 18-30 cm, syringe pushing speed 0.03-0.05 mm / min, ambient humidity RH 20%-40%, temperature 25-30° C., and voltage 15-18 kV.

[0020] Preferably, the stabilization treatment includes: first heating to a first temperature and performing a first heat preservation, and then second heating from the first temperature to a second temperature and performing a second heat preservation.

[0021] Preferably, the first temperature is 120° C., the first insulation time is 12 to 15 hours, the second temperature is 180° C., and the second insulation time is 2 to 6 hours.

[0022] Preferably, the first heating time is 40 to 60 minutes; the second heating time is 45 to 75 hours.

[0023] Preferably, the protective atmosphere includes nitrogen and / or argon; the gas flow rate of the protective atmosphere is 80-100 sccm.

[0024] Preferably, the organic solvent is N,N-dimethylformamide; the mass ratio of the resin to the organic solvent is 5:(10-15).

[0025] Preferably, the mixing is carried out under stirring conditions; the stirring rate is 600-1000 rpm.

[0026] Preferably, the solid-liquid separation is performed by centrifugation; the rotation speed of the centrifugation is 4000-8000 rpm; and the time of the centrifugation is ≥4 min.

[0027] The present application also provides the use of the concentrated ultra-microporous activated carbon fiber material described in the above technical solution or the concentrated ultra-microporous activated carbon fiber material prepared by the preparation method described in the above technical solution in the adsorption separation of benzene and cyclohexane.

[0028] The present application also provides a method for the adsorption separation of benzene and cyclohexane, comprising the following steps:

[0029] The concentrated ultra-microporous activated carbon fiber material is placed in a fixed bed layer to perform adsorption separation on a mixed gas containing benzene and cyclohexane, thereby obtaining the ultra-microporous activated carbon fiber material fixing benzene and the tail gas containing cyclohexane.

[0030] The concentrated ultra-microporous activated carbon fiber material is the concentrated ultra-microporous activated carbon fiber material described in the above technical solution or the concentrated ultra-microporous activated carbon fiber material prepared by the preparation method described in the above technical solution.

[0031] Preferably, the adsorption capacity of the concentrated ultramicroporous activated carbon fiber material for benzene is 0.65 to 0.88 mmol / g.

[0032] Preferably, the temperature of the adsorption separation is 20 to 100°C;

[0033] Preferably, the volume ratio of benzene to cyclohexane is (1-99):(1-99); and the flow rate of the mixed gas is 0.1-100 sccm.

[0034] Preferably, the load gas in the adsorption separation is one or more of nitrogen, helium and argon; and the volume ratio of the mixed gas to the load gas is (1-2):(1-5).

[0035] Preferably, after the adsorption separation is completed, the method further comprises: desorbing the ultra-microporous activated carbon fiber material that fixes benzene and then reusing it.

[0036] Preferably, the desorption treatment is heating and purging; the temperature of the heating and purging is 80 to 200°C; the purge gas used for the heating and purging is one or more of nitrogen, argon and helium; the flow rate of the purge gas is 80 to 200 sccm; and the time of the heating and purging is 1 to 5 hours.

[0037] Preferably, the number of reuses is 3 to 8 times.

[0038] The present application provides a concentrated ultra-microporous activated carbon fiber material having a pore size of The pore size distribution concentration is 90-100%. The concentrated ultra-microporous activated carbon fiber material provided by the present application has a concentrated pore size, and the pore size is between the kinetic diameters of benzene and cyclohexane. The resulting sieving effect separates benzene and cyclohexane. Simultaneously, the π-π interaction between the C=C double bond on the surface of the concentrated ultraporous activated carbon fiber and the π bond of benzene selectively adsorbs benzene and cyclohexane. The combined effects of pore size screening and surface interaction result in different adsorption penetration points for benzene and cyclohexane on the concentrated ultraporous activated carbon fiber: cyclohexane penetrates within 1 to 3 minutes, while benzene penetrates within 42 to 57 minutes. High resolution is maintained over a wide time window, achieving the separation of benzene and cyclohexane. The separation process is simple, efficient, and energy-efficient, with low energy consumption and energy conservation. The structural stability is high, and the material is not susceptible to deactivation and denaturation. It is stable, reusable, and cost-effective, making it suitable for industrial separation.

[0039] The present application also provides a method for preparing the above-mentioned concentrated ultra-microporous activated carbon fiber material, by stabilizing and carbonizing the fiber precursors prepared by electrospinning, and controlling the heating rate and carbonization activation temperature, so that the pore size distribution and concentration of the activated carbon fiber are more conducive to the separation of benzene and cyclohexane, and the prepared concentrated ultra-microporous activated carbon fiber material has high structural stability, is not easily deactivated and denatured, and can be stably reused. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] FIG1 is a diagram of the temperature rise schedule for the stabilization treatment in Example 1;

[0041] FIG2 is a SEM image of the concentrated ultramicroporous activated carbon fiber material (ACF-1000° C.) prepared in Example 2;

[0042] FIG3 is a pore size distribution diagram of concentrated ultramicroporous activated carbon fiber materials prepared in Examples 1 to 3;

[0043] FIG4 is a graph showing the adsorption capacity of concentrated ultramicroporous activated carbon fiber materials (ACF-800°C, ACF-1000°C, ACF-1200°C) prepared in Examples 2 and 3;

[0044] FIG5 is a penetration adsorption diagram of ACF-800°C in Example 2;

[0045] FIG6 is a penetration adsorption diagram of ACF-1000°C in Example 2;

[0046] FIG7 is a penetration adsorption diagram of ACF-1200°C in Example 3;

[0047] FIG8 is a penetration adsorption diagram of the commercially available activated carbon fiber material of Comparative Example 1;

[0048] FIG9 is a static adsorption curve of benzene and cyclohexane by the ACF-1000°C material in Example 2;

[0049] FIG10 is a graph showing the cyclic adsorption performance of the ACF-1000°C material after adsorption and separation of benzene and cyclohexane in the application example. DETAILED DESCRIPTION

[0050] The present application provides a concentrated ultra-microporous activated carbon fiber material having a pore size of The pore size distribution concentration is 90-100%.

[0051] In the present application, the C mass content of the concentrated ultra-microporous activated carbon fiber material is preferably 84-92%, more preferably 85-91.79%, the H mass content is preferably 0.96-1.07%, more preferably 0.96-1%, the O mass content is preferably 4.54-7.14%, more preferably 4.54-7%, and the N mass content is preferably 1.32-3.71%, more preferably 1.32-3%; the pore size of the concentrated ultra-microporous activated carbon fiber material is Preferably The pore size distribution concentration is 90-100%, preferably 95-100%, the diameter is preferably 0.6-0.82 μm, more preferably 0.63-0.8 μm, and the t-plot specific surface area is preferably 555-696 m 2 / g, more preferably 600 to 680 m 2 / g, and the t-plot pore volume is preferably 0.21 to 0.26 cm 3 / g, more preferably 0.23 to 0.25 cm 3 / g.

[0052] The concentrated ultra-microporous activated carbon fiber material provided by the present application has a concentrated pore size, and the pore size is between the kinetic diameters of benzene and cyclohexane. The resulting sieving effect separates benzene and cyclohexane. Simultaneously, the π-π interaction between the C=C double bonds on the surface of the concentrated ultraporous activated carbon fiber and the π bonds of benzene selectively adsorbs benzene and cyclohexane. The combined effects of pore size screening and surface interaction result in different adsorption penetration points for benzene and cyclohexane on the concentrated ultraporous activated carbon fiber, maintaining high resolution over a wide time window and achieving separation of benzene and cyclohexane. This separation process is simple, efficient, energy-efficient, and structurally stable. The material is not susceptible to deactivation and denaturation, allowing for stable, reusable, low-cost, and recyclable use, making it suitable for industrial separation.

[0053] The present application also provides a method for preparing the concentrated ultra-microporous activated carbon fiber material described in the above technical solution, comprising the following steps:

[0054] The resin, organic solvent and additive are mixed, and the obtained suspension is subjected to solid-liquid separation to obtain a supernatant;

[0055] electrospinning the supernatant to prepare a fiber mat, and stabilizing the obtained fiber mat in an air atmosphere to obtain a stabilized fiber mat;

[0056] The stabilized fiber felt is carbonized and activated under a protective atmosphere to obtain a concentrated ultra-microporous activated carbon fiber material;

[0057] The carbonization activation process is as follows: heating to 800-1200° C. at 1-6° C. / min, cooling to 180-200° C. at 3-8° C. / min, and finally naturally cooling to room temperature.

[0058] Unless otherwise specified, this application has no special requirements on the sources of the raw materials used in the preparation, and commercially available products known to those skilled in the art can be used.

[0059] In the present application, resin, organic solvent and auxiliary agent are mixed, and the obtained suspension is subjected to solid-liquid separation to obtain a supernatant.

[0060] In the present application, the resin is preferably a phenolic resin; the auxiliary agent preferably includes polyvinyl pyrrolidone and / or polyvinyl butyral, more preferably polyvinyl pyrrolidone; the mass ratio of the resin to the auxiliary agent is preferably 5:(1-5), more preferably 5:(2-3).

[0061] In the present application, the organic solvent is preferably N,N-dimethylformamide; the mass ratio of the resin to the organic solvent is preferably 5:(10-15), more preferably 5:(12-15).

[0062] In the present application, the mixing is preferably carried out under stirring conditions; the stirring rate is preferably 600-1000 rpm, more preferably 700-800 rpm; the present application has no special limitation on the stirring time, as long as the materials are mixed evenly.

[0063] In the present application, the solid-liquid separation is preferably centrifugation; the centrifugal speed is preferably 4000-8000 rpm, more preferably 5000-6000 rpm; the centrifugal time is preferably ≥4 min, more preferably 5-10 min.

[0064] After obtaining the supernatant, the present application performs electrostatic spinning on the supernatant to prepare a fiber felt.

[0065] In the present application, the conditions for electrospinning include: the needle model is preferably 16 to 24, more preferably 18 to 20; the receiving distance is preferably 18 to 30 cm, more preferably 20 to 25 cm; the push speed of the syringe is preferably 0.03 to 0.05 mm / min, more preferably 0.04 mm / min; the ambient humidity is preferably RH20 to 40%, more preferably 25 to 35%; the temperature is preferably 25 to 30°C, more preferably 25°C; the voltage is preferably 15 to 18 kV, more preferably 16 to 17 kV.

[0066] After obtaining the fiber mat, the present application performs a stabilization treatment on the fiber mat in an air atmosphere to obtain a stabilized fiber mat.

[0067] In the present application, the stabilization treatment preferably includes: first heating to a first temperature and performing a first heat preservation, and then second heating from the first temperature to a second temperature and performing a second heat preservation.

[0068] In the present application, the first temperature is preferably 120°C, the first insulation time is preferably 12 to 15 hours, more preferably 13 to 14 hours; the second temperature is preferably 180°C, the second insulation time is preferably 2 to 6 hours, more preferably 3 to 5 hours.

[0069] In the present application, the first heating time is preferably 40 to 60 minutes, more preferably 45 to 55 minutes; the second heating time is preferably 45 to 75 hours, more preferably 50 to 70 hours.

[0070] During the stabilization process, the resin undergoes cross-linking with the presence of oxygen, increasing the material's strength. Furthermore, due to the introduction of oxygen atoms, these oxygen atoms escape from the material during carbonization and activation, thereby increasing the material's specific surface area. The present invention achieves stabilization through cross-linking, primarily due to the stability of the resin in the material and the high structural stability of the material, making it less susceptible to deactivation and denaturation, and enabling stable and reusable use.

[0071] After obtaining the stabilized fiber felt, the present application performs carbonization activation on the stabilized fiber felt under a protective atmosphere to obtain concentrated ultra-microporous activated carbon fiber material.

[0072] In the present application, the protective atmosphere preferably includes nitrogen and / or argon, more preferably argon; the gas flow rate of the protective atmosphere is preferably 80 to 100 sccm, more preferably 85 to 95 sccm.

[0073] In the present application, the carbonization activation process is: heating to 800-1200°C at 1-6°C / min, cooling to 180-200°C at 3-8°C / min, and finally naturally cooling to room temperature. Preferably, the process is: heating to 900-1100°C at 2-5°C / min, cooling to 200°C at 4-6°C / min, and finally naturally cooling to room temperature.

[0074] The present application improves the adsorption performance of concentrated ultra-microporous activated carbon fiber materials through high-temperature carbonization activation, and limits the carbonization activation temperature within the above-mentioned range to avoid excessive carbonization or incomplete carbonization of the stabilized fiber felt due to excessively high or low temperatures, which affects the pore size distribution and concentration of the activated carbon fiber material and thus reduces its separation performance; the heating rate to the carbonization activation temperature is limited within the above-mentioned range to avoid the pore size distribution and concentration being unfavorable due to the heating rate being too fast or too slow, and the concentrated pore size activated carbon fiber material with the best separation effect is obtained by controlling the heating rate and the carbonization activation temperature. In addition, the high-temperature carbonization activation can also improve the structural stability of the concentrated ultra-microporous activated carbon fiber material, making the material less likely to be deactivated and denatured, and capable of stable repeated use.

[0075] The present application also provides the use of the concentrated ultra-microporous activated carbon fiber material described in the above technical solution or the concentrated ultra-microporous activated carbon fiber material prepared by the preparation method described in the above technical solution in the adsorption separation of benzene and cyclohexane.

[0076] The present application also provides a method for the adsorption separation of benzene and cyclohexane, comprising the following steps:

[0077] The concentrated ultra-microporous activated carbon fiber material is placed in a fixed bed layer to perform adsorption separation on a mixed gas containing benzene and cyclohexane, thereby obtaining the ultra-microporous activated carbon fiber material fixing benzene and the tail gas containing cyclohexane.

[0078] The concentrated ultra-microporous activated carbon fiber material is the concentrated ultra-microporous activated carbon fiber material described in the above technical solution or the concentrated ultra-microporous activated carbon fiber material prepared by the preparation method described in the above technical solution.

[0079] In the present application, the adsorption amount of the concentrated ultra-microporous activated carbon fiber material for benzene is preferably 0.65-0.88 mmol / g, more preferably 0.70-0.80 mmol / g, and most preferably 0.75 mol / g; the temperature of the adsorption separation is preferably 20-100°C, more preferably 25-30°C, and most preferably 25°C; the volume ratio of benzene and cyclohexane is preferably (1-99):(1-99), more preferably (20-50):(50-80), and most preferably 50:50; the flow rate of the mixed gas is preferably 0.1-100 sccm, more preferably 1-50 sccm; the load gas in the adsorption separation is preferably one or more of nitrogen, helium and argon, more preferably nitrogen; the volume ratio of the mixed gas and the load gas is preferably (1-2):(1-5), more preferably (1-2):(1-3), and most preferably 1:1.

[0080] After the adsorption separation is completed, the present application preferably further includes: desorbing the ultra-microporous activated carbon fiber material that fixes benzene and then reusing it; the desorption treatment is preferably heating and purging; the temperature of the heating and purging is preferably 80-200°C, more preferably 100-200°C; the purge gas used for the heating and purging is preferably one or more of nitrogen, argon and helium, more preferably nitrogen; the flow rate of the purge gas is preferably 80-200sccm, more preferably 100-150sccm, and most preferably 100sccm; the time of the heating and purging is preferably 1-5h, more preferably 2-3h; the number of times of the reuse is preferably 3-8 times, more preferably 5 times.

[0081] The ultra-microporous activated carbon fiber material provided in the present application can be reused after desorption, and its adsorption and separation performance has almost no attenuation, and the material stability is high.

[0082] The technical solutions in this application will be clearly and completely described below in conjunction with the embodiments in this application, but they should not be understood as limiting the scope of protection of this application.

[0083] Example 1

[0084] 2.2 g of polyvinylpyrrolidone (PVP) was added to 15 g of N,N-dimethylformamide (DMF) and stirred until completely dissolved. Then, 5 g of phenolic resin was added and stirred at 800 rpm to obtain a uniform suspension. The suspension was centrifuged at 8000 rpm for 4 min to remove insoluble matter and obtain a supernatant.

[0085] The supernatant was subjected to electrospinning using a No. 22 needle, a receiving distance of 23.5 cm, a solution pushing speed of 0.04 mm / min, an ambient humidity of RH30%, a temperature of 28° C., and a voltage of 16.5 kV to obtain a fiber mat;

[0086] The fiber felt was placed in an oven and programmed to undergo stabilization treatment, specifically, the temperature was raised from room temperature to 120°C over 40 minutes, maintained at 120°C for 12 hours, then raised from 120°C to 180°C over 60 hours, and maintained at 180°C for 2 hours, to obtain a yellow fiber cloth having a certain degree of flexibility and strength, which is a stabilized fiber felt. The temperature rise program is shown in FIG1 ;

[0087] The stabilized fiber felt was heated to 1000°C at heating rates of 1°C / min, 2°C / min, 4°C / min, and 6°C / min under a nitrogen atmosphere with a gas flow rate of 100 sccm, then cooled to 200°C at a cooling rate of 5°C / min, and finally naturally cooled to room temperature to obtain concentrated ultramicroporous activated carbon fiber materials (respectively recorded as ACF-1°C / min, ACF-2°C / min, ACF-4°C / min, and ACF-6°C / min).

[0088] Example 2

[0089] 2.2 g of polyvinylpyrrolidone (PVP) was added to 15 g of N,N-dimethylformamide (DMF) and stirred until completely dissolved. Then, 5 g of phenolic resin was added and stirred at 800 rpm to obtain a uniform suspension. The suspension was centrifuged at 8000 rpm for 4 min to remove insoluble matter and obtain a supernatant.

[0090] The supernatant was subjected to electrospinning using a No. 22 needle, a receiving distance of 23.5 cm, a solution pushing speed of 0.04 mm / min, an ambient humidity of RH30%, a temperature of 28° C., and a voltage of 16.5 kV to obtain a fiber mat;

[0091] The fiber felt was placed in an oven and programmed to undergo stabilization treatment, specifically, the temperature was raised from room temperature to 120°C over 40 minutes, maintained at 120°C for 12 hours, then raised from 120°C to 180°C over 60 hours, and maintained at 180°C for 2 hours, to obtain a yellow fiber cloth having a certain degree of flexibility and strength, which is a stabilized fiber felt. The temperature program is shown in FIG1 ;

[0092] The stabilized fiber felt was heated to 800°C and 1000°C at a heating rate of 2°C / min under a nitrogen atmosphere with a gas flow rate of 100 sccm, then cooled to 200°C at a cooling rate of 5°C / min, and finally naturally cooled to room temperature to obtain concentrated ultramicroporous activated carbon fiber materials (respectively recorded as ACF-800°C and ACF-1000°C).

[0093] Example 3

[0094] 2.2 g of polyvinylpyrrolidone (PVP) was added to 15 g of N,N-dimethylformamide (DMF) and stirred until completely dissolved. Then, 5 g of phenolic resin was added and stirred at 800 rpm to obtain a uniform suspension. The suspension was centrifuged at 8000 rpm for 4 min to remove insoluble matter and obtain a supernatant.

[0095] The supernatant was subjected to electrospinning using a No. 22 needle, a receiving distance of 23.5 cm, a solution pushing speed of 0.04 mm / min, an ambient humidity of RH30%, a temperature of 28° C., and a voltage of 16.5 kV to obtain a fiber mat;

[0096] The fiber felt was placed in an oven and programmed to undergo stabilization treatment, specifically, the temperature was raised from room temperature to 120°C over 40 minutes, maintained at 120°C for 12 hours, then raised from 120°C to 180°C over 60 hours, and maintained at 180°C for 2 hours, to obtain a yellow fiber cloth having a certain degree of flexibility and strength, which is a stabilized fiber felt. The temperature rise program is shown in FIG1 ;

[0097] The stabilized fiber felt was heated to 1200°C at a heating rate of 2°C / min under a nitrogen atmosphere with a gas flow rate of 100 sccm, then cooled to 200°C at a cooling rate of 5°C / min, and finally naturally cooled to room temperature to obtain a concentrated ultra-microporous activated carbon fiber material (denoted as ACF-1200°C).

[0098] Comparative Example 1

[0099] Commercially available phenolic-based activated carbon fibers were used as a comparative example.

[0100] Application Examples

[0101] The concentrated ultra-microporous activated carbon fiber materials (ACF-1°C / min, ACF-2°C / min, ACF-4°C / min, ACF-6°C / min, ACF-800°C, ACF-1000°C) prepared in Examples 1 to 2 were placed in a fixed bed for adsorption separation of a mixed gas of benzene and cyclohexane. The adsorption separation temperature was 25°C, the volume ratio of benzene and cyclohexane was 50:50, the flow rate of the mixed gas was 50 sccm, the load gas in the adsorption separation was nitrogen, and the volume ratio of the mixed gas to the load gas was 1:1.

[0102] Performance Testing

[0103] (1) Figure 2 is a SEM image of the concentrated ultramicroporous activated carbon fiber material (ACF-1000°C) prepared in Example 2.

[0104] As shown in Figure 2, the fibers are in good condition and have obvious fiber filaments without obvious breaks.

[0105] (2) The pore size of the concentrated ultra-microporous activated carbon fiber materials (ACF-1°C / min, ACF-2°C / min, ACF-4°C / min, ACF-6°C / min, ACF-800°C, ACF-1000°C, ACF-1200°C) prepared in Examples 1 to 3 was tested. Specifically, nitrogen adsorption and desorption were used for the test: 40 to 60 mg of dry sample was weighed and placed in a test tube for vacuum degassing. After the degassing was completed, the nitrogen 77K adsorption and desorption curve of each sample was tested respectively, and the pore size distribution of the material was calculated by NLDFT. The results are shown in Figure 3.

[0106] As shown in Figure 3, the pore size concentration of the concentrated ultra-microporous activated carbon fiber material (ACF-2℃ / min) with a heating rate of 2℃ / min is the best. The pore size is between the molecular dynamics diameters of benzene and cyclohexane At other heating rates, different types of pores appear, and the specific surface area is relatively small. At a heating rate of 2°C / min, the temperature is raised to 800°C, 1000°C and 1200°C respectively. As the temperature increases, the specific surface area also increases accordingly, but the pore size distribution of the material changes due to the increase in temperature. The material activated by carbonization at 1200°C has All materials showed typical type I N2 adsorption isotherms, and the pore size distribution surface indicated ultramicropores.

[0107] (3) The adsorption results of the concentrated ultra-microporous activated carbon fiber materials (ACF-800℃, ACF-1000℃, ACF-1200℃) prepared in Examples 2 to 3 are shown in Figure 4. The specific test process is the BET adsorption-desorption test, which calculates the material specific surface area, pore size and other physical properties by the volume method at 77K. Test conditions: Take 40 mg of sample in a test tube, first degas the part, use a heating bag to increase the temperature to 200℃ at a rate of 5℃ / min, and then keep it for 6 hours. After the degassing is completed, call the existing template (the standard microporous test template of the BET test instrument of Mack) to test the sample

[0108] According to the test results in Figure 4, the specific surface area of ​​the material increases with the increase of carbonization activation temperature.

[0109] (4) Dynamic adsorption separation test.

[0110] A dynamic adsorption device analyzes the adsorption and separation properties of materials under dynamic flow conditions. Its principle is to use a penetrating column loaded with activated carbon fiber as the adsorption and separation material, which is stacked into a bed of a certain height. The bed is stationary. A mixed gas flows through the adsorber inlet, is adsorbed by the bed, and then flows out through the outlet. Chromatography is used to measure the concentration of each component in the outlet gas over time and generate a breakthrough curve. The breakthrough time of components other than the carrier gas and the selective adsorption capacity of each component of the mixed gas by the activated carbon fiber can also be measured.

[0111] Testing was conducted using the commercially available activated carbon fiber materials from Example 2 (ACF-800°C), Example 3 (ACF-1200°C), and Comparative Example 1. The test conditions were: a 50:50 volume ratio of benzene and cyclohexane, each with a concentration of 500 ppm, nitrogen as the carrier gas, a test flow rate of 50 seem, a test temperature of 25°C, and an adsorbent bed mass of 30 mg. Breakthrough adsorption plots for the four materials were obtained, and the results are shown in Figures 5, 6, 7, and 8, respectively. The horizontal axis in each figure represents time, and the vertical axis, C / C0, represents the ratio of the outlet concentration to the inlet concentration, i.e., the relative concentration. Breakthrough is considered to have occurred when the outlet concentration reaches 5% of the inlet concentration, and the corresponding point is referred to as the breakthrough point.

[0112] As shown in Figures 5 and 6, the separation times for ACF-800°C and ACF-1000°C are 42 minutes and 57 minutes, respectively (separation time is equal to the difference in breakthrough time between the two materials). The corresponding dynamic adsorption capacities for benzene and cyclohexane are 0.65 / 0.04 mmol / g and 0.75 / 0.06 mmol / g, respectively. This demonstrates that these materials can achieve the separation of benzene and cyclohexane, with ACF-1000°C exhibiting superior separation performance.

[0113] As can be seen from Figures 7 and 8, the separation time of ACF-1200℃ and commercially available Sutong Company's activated carbon fiber is 42min and 6min respectively. The dynamic adsorption capacity of the corresponding materials for benzene / cyclohexane is 0.88 / 0.23mmol / g and 0.58 / 0.36mmol / g. It is proved that ACF-1200℃ also has a certain benzene / cyclohexane separation effect, but due to the generation of 7.5a mixed pores, although the specific surface area has been greatly improved, the separation performance has not been improved accordingly. The commercially available activated carbon fiber has almost no separation ability due to its non-concentrated pore size. It can be concluded that ACF-1000℃ has a concentrated The pore size plays a key role in the separation of benzene and cyclohexane.

[0114] (5) The ACF-1000℃ material with the best separation performance in the application example was used to perform static adsorption performance tests using an intelligent gravimetric analyzer (IGA-100).

[0115] The intelligent gravimetric adsorption instrument uses a highly precise gravimetric method to examine the adsorption performance of solid adsorbents. The IGA-100 comprises a thermostatic balance, temperature control system, high vacuum system, pressure control system, piping system, and real-time online display software, forming a complete gravimetric adsorption testing system. Before testing, the sample undergoes a degassing pretreatment under the control of the temperature and pressure control system. The weight of the degassed sample is then read and recorded. During the adsorption test, by precisely controlling the temperature and vapor pressure, the sample weight changes as the adsorption process progresses. During this process, changes in weight, pressure, and temperature are recorded and stored in real time by a computer. The temperature control system allows the temperature during adsorption to be adjusted, allowing adsorption isotherms to be obtained at different temperatures.

[0116] Test conditions: material mass 40 mg, benzene and cyclohexane used were of HPLC purity, test temperature was 25°C, and static adsorption curves of benzene and cyclohexane for ACF-1000°C material were obtained, respectively. The results are shown in Figure 9.

[0117] Figure 9 shows that the static saturated adsorption capacities for benzene and cyclohexane are 2.52 mmol / g and 0.37 mmol / g, respectively. This indicates that the concentrated ultra-microporous activated carbon fiber material prepared in this application exhibits a high adsorption capacity for benzene, while only exhibiting a low adsorption capacity for cyclohexane. The excellent separation performance of the concentrated ultra-microporous activated carbon fiber material was further validated in the static test.

[0118] (6) The ACF-1000℃ material after the adsorption separation of benzene and cyclohexane in the application example was used as the adsorption separation material. It was heated at 200℃ and purged with a nitrogen flow rate of 100 sccm for regeneration. This was repeated 5 times to test the cyclic adsorption performance. The results are shown in Figure 10.

[0119] As shown in FIG10 , the concentrated ultramicroporous activated carbon fiber material prepared in the present application has good cyclic adsorption and separation performance, and the separation performance hardly decays during the 5 cycles.

[0120] Although the above embodiment provides a detailed description of the present application, it is only a part of the embodiments of the present application rather than all the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present application.

Claims

1. A concentrated ultra-microporous activated carbon fiber material, characterized in that: The pore size of the concentrated ultra-microporous activated carbon fiber material is The pore size distribution concentration is 90-100%.

2. The concentrated ultra-microporous activated carbon fiber material according to claim 1, characterized in that: The concentrated ultra-microporous activated carbon fiber material has a diameter of 0.6 to 0.82 μm and a t-plot specific surface area of 555 to 696 m 2 / g, t-plot pore volume is 0.21~0.26cm 3 / g.

3. The concentrated ultra-microporous activated carbon fiber material according to claim 1, characterized in that: The surface of the concentrated ultramicroporous activated carbon fiber material has C=C double bonds.

4. The concentrated ultra-microporous activated carbon fiber material according to claim 1, characterized in that: The concentrated ultramicroporous activated carbon fiber material has a C mass content of 84-92%, a H mass content of 0.96-1.07%, an O mass content of 4.54-7.14%, and a N mass content of 1.32-3.71%.

5. The method for preparing the concentrated ultra-microporous activated carbon fiber material according to any one of claims 1 to 4, characterized in that: The following steps are involved: The resin, organic solvent and auxiliary agent are mixed, and the obtained suspension is subjected to solid-liquid separation to obtain a supernatant; electrospinning the supernatant to prepare a fiber mat, and stabilizing the obtained fiber mat in an air atmosphere to obtain a stabilized fiber mat; The stabilized fiber felt is carbonized and activated under a protective atmosphere to obtain a concentrated ultra-microporous activated carbon fiber material; The carbonization activation process is as follows: heating to 800-1200° C. at a rate of 1-6° C. / min, cooling to 180-200° C. at a rate of 3-8° C. / min, and finally naturally cooling to room temperature.

6. The preparation method according to claim 5, characterized in that The resin is phenolic resin; the auxiliary agent includes polyvinyl pyrrolidone and / or polyvinyl butyral.

7. The preparation method according to claim 6, characterized in that The mass ratio of the resin to the auxiliary agent is 5:(1-5).

8. The preparation method according to claim 5, characterized in that The electrospinning conditions include: needle size 16-24, receiving distance 18-30 cm, syringe pushing speed 0.03-0.05 mm / min, ambient humidity RH 20%-40%, temperature 25-30° C., and voltage 15-18 kV.

9. The preparation method according to claim 5, characterized in that The stabilization treatment includes: first heating to a first temperature and performing a first heat preservation, and then second heating from the first temperature to a second temperature and performing a second heat preservation.

10. The preparation method according to claim 9, characterized in that The first temperature is 120° C., the first heat preservation time is 12 to 15 hours, the second temperature is 180° C., and the second heat preservation time is 2 to 6 hours.

11. The preparation method according to claim 9, characterized in that The first heating time is 40 to 60 minutes; the second heating time is 45 to 75 hours.

12. The preparation method according to claim 5, characterized in that The protective atmosphere includes nitrogen and / or argon; the gas flow rate of the protective atmosphere is 80-100 sccm.

13. The preparation method according to claim 5, characterized in that The organic solvent is N,N-dimethylformamide; the mass ratio of the resin to the organic solvent is 5:(10-15).

14. The preparation method according to claim 5, characterized in that The mixing is carried out under stirring conditions; the stirring rate is 600-1000 rpm.

15. The preparation method according to claim 5, characterized in that The solid-liquid separation is performed by centrifugation; the centrifugal speed is 4000-8000 rpm; and the centrifugal time is ≥4 min.

16. Use of the concentrated ultramicroporous activated carbon fiber material according to any one of claims 1 to 4 or the concentrated ultramicroporous activated carbon fiber material prepared by the preparation method according to any one of claims 5 to 15 in the adsorptive separation of benzene and cyclohexane.

17. A method for separation of benzene and cyclohexane by adsorption, characterized in that: The following steps are involved: The concentrated ultra-microporous activated carbon fiber material is placed in a fixed bed layer to perform adsorption separation on a mixed gas containing benzene and cyclohexane, thereby obtaining the ultra-microporous activated carbon fiber material fixing benzene and the tail gas containing cyclohexane. The concentrated ultra-microporous activated carbon fiber material is the concentrated ultra-microporous activated carbon fiber material according to any one of claims 1 to 4 or the concentrated ultra-microporous activated carbon fiber material prepared by the preparation method according to any one of claims 5 to 15.

18. The adsorption separation method according to claim 17, characterized in that: The adsorption capacity of the concentrated ultra-microporous activated carbon fiber material for benzene is 0.65-0.88 mmol / g.

19. The adsorption separation method according to claim 17, characterized in that: The temperature of the adsorption separation is 20 to 100°C; 20. The adsorption separation method according to claim 17, characterized in that: The volume ratio of benzene to cyclohexane in the mixed gas is (1-99):(1-99); and the flow rate of the mixed gas is 0.1-100 sccm.

21. The adsorption separation method according to claim 17 or 20, characterized in that: The load gas in the adsorption separation is one or more of nitrogen, helium and argon; the volume ratio of the mixed gas to the load gas is (1-2):(1-5).

22. The adsorption separation method according to claim 17, characterized in that: After the adsorption separation is completed, the method further includes: desorbing the ultra-microporous activated carbon fiber material that fixes benzene and then reusing it.

23. The adsorption separation method according to claim 22, characterized in that: The desorption treatment is heating and purging; the temperature of the heating and purging is 80-200°C; the purging gas used for the heating and purging is one or more of nitrogen, argon and helium; the flow rate of the purging gas is 80-200sccm; and the time of the heating and purging is 1-5h.

24. The adsorption separation method according to claim 22 or 23, characterized in that: The number of times of repeated utilization is 3 to 8 times.

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