High-compression-resistance carbon molecular sieve and preparation process thereof

Abstract

The invention relates to the field of carbon molecular sieves, and particularly discloses a high-pressure-resistance carbon molecular sieve and a preparation process thereof. The preparation process comprises the following steps: S1, pretreatment of raw materials: crushing flower mud, dispersing the crushed flower mud and tetraethoxysilane in ethanol according to a weight ratio of 100: (1.5-3), carrying out a stirring reaction under the condition that the pH value is 9-10, adjusting the pH value to 7 after the reaction is finished, and carrying out filtering, washing, drying and ball milling to obtain flower mud powder; s2, mixing and forming: blending the flower mud powder, liquid phenolic resin, a binder and water, stirring, kneading, extruding and forming to obtain a blank body; and S3, carbonization and deposition: heating the green body for carbonization, then raising the temperature, adding benzene for deposition, cooling and screening to obtain the high-compression-resistance carbon molecular sieve. The compressive strength of the high-compressive-strength carbon molecular sieve is greater than or equal to 105N / particle, the bulk density is less than or equal to 670g / L, and the high-compressive-strength carbon molecular sieve has excellent nitrogen production capacity, high mechanical strength and low bulk density.

Description

Technical Field

[0001] This application relates to the technical field of carbon molecular sieves, and particularly to a high-compressive carbon molecular sieve and its preparation process. Background Art

[0002] Due to its unique pore structure and surface chemical properties, carbon molecular sieve exhibits important values in many fields. In the field of gas separation, it can efficiently separate different types of gases, improve gas purity, and provide high-quality feed gas for chemical production; in catalysis, its special surface properties can be used as a catalyst support to enhance the efficiency and selectivity of catalytic reactions; in the field of energy storage, it also provides possibilities for the research and development of new energy storage materials. With the continuous progress of technology, the requirements for the performance of carbon molecular sieves are also increasing day by day, and its application prospects in various fields are very broad.

[0003] In the preparation of traditional carbon molecular sieves, the common method is to achieve it through the carbonization of polymers or biomass. This method is relatively simple to operate and the raw materials are relatively easy to obtain. However, this traditional method faces some challenges. In addition, in recent years, biomass-derived carbon materials have received extensive attention due to their low cost and renewable nature. However, in the process of biomass carbonization, there are common problems, such as large volume shrinkage after carbonization, which will lead to poor structural stability, and the pore structure is uneven, affecting its performance in gas adsorption and separation processes. In order to improve these situations, chemical activation or physical activation methods are often used in the prior art to optimize the pore structure. Chemical activation generally uses specific chemical reagents to react with carbon materials to form more pores; physical activation is to change the structure of carbon materials and increase the porosity through physical means such as high temperature and gas atmosphere.

[0004] However, these existing preparation methods have obvious limitations. Whether it is the traditional polymer or biomass carbonization method, or the method of using chemical activation or physical activation to improve biomass-derived carbon materials, it is difficult to achieve the goals of high mechanical strength and low bulk density at the same time. Summary of the Invention

[0005] In order to solve the above technical problems, this application provides a high-compressive carbon molecular sieve and its preparation process.

[0006] In a first aspect, the present application provides a preparation process for a high-compressive carbon molecular sieve, comprising the following steps: S1. Pretreatment of raw materials: After crushing the flower mud, it is dispersed in ethanol with tetraethyl orthosilicate in a weight ratio of 100:(1.5 - 3), and stirred and reacted under the condition of pH = 9 - 10. After the reaction, the pH is adjusted to 7, the solid is filtered out, washed, dried, and ball-milled to obtain flower mud powder; S2. Mixing and forming: The flower mud powder obtained in step S1, liquid phenolic resin, binder, and water are blended in a weight ratio of (35 - 40):(10 - 15):20:30, stirred, kneaded, extruded, and formed to obtain a green body; S3. Carbonization and deposition: The green body is heated for carbonization, then the temperature is adjusted to 700 - 800 °C, benzene is added for deposition, and after the deposition is completed, it is cooled and screened to obtain a high-compressive carbon molecular sieve.

[0007] By adopting the above technical solution, first, the present application blends the flower mud with tetraethyl orthosilicate, adjusts the pH of the system to be alkaline, and makes tetraethyl orthosilicate undergo hydrolysis and condensation reaction. The formed silicon dioxide particles will be more evenly distributed in the flower mud base material. The hydroxyl groups on the surface of the silicon dioxide particles will undergo dehydration condensation reaction with the hydroxymethyl groups on the surface of the flower mud to form Si - O - C covalent bonds, forming a relatively good bonding interface; Subsequently, the present application blends the flower mud powder obtained after being modified by tetraethyl orthosilicate and post-treatment with liquid phenolic resin, binder, and water, stirs, kneads, extrudes, and forms to obtain a green body. The present application controls the ratio between the materials here to ensure that the micropore proportion in the finally formed carbon molecular sieve is appropriate. At the same time, the flower mud powder and liquid phenolic resin are the active precursors of the carbon molecular sieve, so their proportions directly affect the number of micropores in the carbon molecular sieve. The binder belongs to the "inactive component". Excessive addition will block the micropores of the carbon molecular sieve, and insufficient addition will lead to poor structural stability of the carbon molecular sieve; Finally, the present application heats and carbonizes the green body, and some Si - O - C covalent bonds will form a SiO 2 / C composite skeleton to further improve the compressive strength of the carbon molecular sieve. Then benzene is added for pore formation by deposition, cooled after completion, and screened to obtain a high-compressive carbon molecular sieve with both high mechanical strength and low bulk density. After testing, its compressive strength ≥ 105 N / particle, and the bulk density ≤ 670 g / L. Moreover, the main raw material of the high-compressive carbon molecular sieve of the present application is flower mud. The product quality of the carbon molecular sieve with a high flower mud content is more stable and has a longer service life. Compared with the carbon molecular sieve with other substances as the base material, the carbon molecular sieve of the present application has a lower air-nitrogen ratio and a higher nitrogen production rate, and has excellent nitrogen production capacity and good mechanical stability.

[0008] Preferably, in step S1, after crushing the flower mud, it is dispersed in ethanol with tetraethyl orthosilicate in a weight ratio of 100:2.5.

[0009] By adopting the above technical solution, the present application strictly controls the weight ratio of the broken floral foam to tetraethyl orthosilicate, enabling the dosage ratio of the silicon dioxide particles formed by the hydrolysis and condensation of tetraethyl orthosilicate to the floral foam base material to be more appropriate. Combining with the overall process steps helps to finally obtain a high-compressive-strength carbon molecular sieve with a compressive strength of up to 110 N / particle.

[0010] Preferably, in step S2, the floral foam powder, liquid phenolic resin, binder, and water obtained in step S1 are blended in a weight ratio of 37.5:12.5:20:30.

[0011] By adopting the above technical solution, the present application strictly controls the weight ratio of the floral foam powder, liquid phenolic resin, binder, and water, further optimizing the structural stability of the carbon molecular sieve and ensuring a more appropriate proportion of micropores in the finally formed carbon molecular sieve.

[0012] Preferably, in step S3, the specific operation of carbonization is as follows: heating up to 600 - 700 °C at a rate of 2 - 5 °C / min, holding for 30 - 60 min for the first-stage carbonization, and then heating up to 800 - 1000 °C at a rate of 1 - 2 °C / min, holding for 30 - 60 min for the second-stage carbonization.

[0013] By adopting the above technical solution, the present application carbonizes the material in two stages and controls different heating rates and holding times respectively, enabling the green body to be carbonized more fully and evenly, helping to form a stable structure, thereby improving the compressive strength of the carbon molecular sieve, reasonably controlling the bulk density, and making both the nitrogen production and nitrogen production concentration of the carbon molecular sieve at a relatively high level.

[0014] Preferably, a mixed gas is also introduced during the second-stage carbonization, and the mixed gas includes carbon dioxide and water vapor with a volume ratio of (1 - 5):1.

[0015] By adopting the above technical solution, the present application also introduces a mixed gas composed of carbon dioxide and water vapor with a volume ratio of (1 - 5):1 during the second-stage carbonization, selectively etching the amorphous carbon region at a temperature of 800 - 1000 °C to form a gradient-distributed microporous-mesoporous structure, optimizing the nitrogen production of the carbon molecular sieve, and further reducing its bulk density without affecting the compressive strength of the carbon molecular sieve.

[0016] Preferably, the mixed gas includes carbon dioxide and water vapor with a volume ratio of (2.5 - 3):1.

[0017] By adopting the above technical solution, the present application further controls the ratio of carbon dioxide and water vapor to be a mixed gas with a ratio of (2.5 - 3):1 during the second-stage carbonization, which helps to further optimize the pore structure and internal composition of the carbon molecular sieve, improve its compressive strength, and reduce the bulk density of the prepared high-compressive-strength carbon molecular sieve by 20 - 25 g / L.

[0018] Preferably, divide the time of the second-stage carbonization equally. In the first stage, control the feeding rate of the mixed gas at 30 - 40 mL / g / min, and in the second stage, control the feeding rate of the mixed gas at 70 - 80 mL / g / min.

[0019] By adopting the above technical solution, in this application, after dividing the second-stage carbonization time equally, the feeding rate of the mixed gas is controlled in stages, which helps to further optimize the carbonization process. First, the mixed gas is slowly fed at a rate of 30 - 40 mL / g / min, which can gently initiate the carbonization reaction and gradually stabilize the internal structure of the carbon molecular sieve to form a basic framework; then, the mixed gas is quickly fed at a rate of 70 - 80 mL / g / min, which can accelerate the carbonization process and further optimize the pore structure, thus facilitating the preparation of a high-compressive carbon molecular sieve with both high mechanical strength and low bulk density.

[0020] Preferably, during the carbonization in step S3, a pulsed current with a frequency of 1 - 5 Hz is also applied to the system.

[0021] By adopting the above technical solution, in this application, a pulsed current is also used as an auxiliary during carbonization. The pulsed electric field formed by the pulsed current can promote the orderly arrangement of the internal microstructure of the carbon molecular sieve, accelerate the carbonization reaction process, and help to form a more stable and uniform pore structure.

[0022] Preferably, during the deposition in step S3, the dosage of benzene is 4 wt% of the total amount of the green body.

[0023] By adopting the above technical solution, in this application, the dosage of benzene is precisely controlled at 4 wt% of the total amount of the green body for deposition, which helps to form a suitable pore structure on the carbonized green body, optimize the pore structure, and thus optimize the nitrogen production and nitrogen production concentration of the carbon molecular sieve.

[0024] In the second aspect, this application provides a high-compressive carbon molecular sieve prepared by the above preparation process. The compressive strength of the high-compressive carbon molecular sieve is ≥ 105 N / particle, and the bulk density is ≤ 670 g / L.

[0025] By adopting the above technical solution, the compressive strength of the high-compressive carbon molecular sieve in this application is ≥ 105 N / particle, and the bulk density is ≤ 670 g / L. Compared with traditional polymer or biomass carbonization methods, and even carbon molecular sieves prepared by methods using chemical activation or physical activation to improve biomass-derived carbon materials, the high-compressive carbon molecular sieve in this application has the advantages of both high compressive strength and low bulk density, showing good development prospects for carbon molecular sieves.

[0026] To sum up, this application has the following beneficial technical effects: 1. The preparation process of this application involves blending flower mud with tetraethyl orthosilicate and controlling the pH of the reaction, enabling silicon dioxide particles to be evenly distributed in the flower mud base material and form covalent bonds, enhancing the material binding force. Moreover, this application precisely controls the material ratio, making the micropore proportion of the carbon molecular sieve more reasonable, ensuring structural stability and smooth micropores; 2. The main raw material of the carbon molecular sieve in this application is flower mud. The product quality of the carbon molecular sieve with a high flower mud content is more stable and has a longer service life. Compared with carbon molecular sieves using other substances as the base material, the carbon molecular sieve in this application has a lower air-nitrogen ratio and a higher nitrogen production rate, and has excellent nitrogen production capacity and good mechanical stability; 3. The high compressive strength carbon molecular sieve of this application has high compressive strength and low bulk density, with a compressive strength ≥ 105 N / particle and a bulk density ≤ 670 g / L, solving the problem that it is difficult to balance high mechanical strength and low bulk density in existing preparation methods. Specific Embodiments

[0027] Material Sources Except as otherwise specified, the raw materials used in this application are all commercially available products, specifically: Flower mud, containing 75 - 80 wt% carbon; The following further elaborates on this application in combination with examples and comparative examples.

[0028] <Example 1.1> A preparation process of a high compressive strength carbon molecular sieve includes the following steps: S1. Pretreatment of raw materials: The flower mud is conveyed to a crusher for crushing treatment by a closed stainless steel conveyor belt. Take 1 kg of the crushed flower mud and disperse 15 g of tetraethyl orthosilicate in 5 L of ethanol. Add a 20 wt% sodium hydroxide solution to adjust the pH of the system to 9 - 10. Heat to 60 °C and stir and react at a rotation speed of 500 r / min for 30 min. Then, increase the temperature at a rate of 2 °C / min to 90 °C, stir for 45 min, cool, add 6 mol / L hydrochloric acid to adjust the pH in the system to 7, filter out the solid, wash it, and pneumatically convey it through a closed pipeline into an electric dryer for drying. The drying removes the moisture in the raw materials, with a drying temperature of 170 °C. Under the scraper plate, the material is continuously lifted and scattered in a spiral progressive manner to achieve heat exchange, and dried until the moisture content is between 0.5 - 5 wt% (within 2 - 3 h). The dried material is pneumatically conveyed through a closed pipeline into a ball mill for ball milling to grind it into a fine powder material, controlling the particle size to be 5 - 30 um to obtain flower mud powder; S2. Mixing and forming: Mix 400 g of the flower mud powder obtained in step S1, 100 g of liquid phenolic resin, 200 g of binder, and 300 mL of water, add them to a mixer for sealed stirring. The flower mud powder is transported to the mixer in a sealed manner, the liquid phenolic resin is pumped to the mixer through a diaphragm pump in a ton barrel, the binder is directly transported through a storage tank pipeline, the opening of the ton barrel is closed. After being evenly kneaded by the mixer, it is extruded into a blank by a twin-screw extruder, obtaining a blank with a diameter of 1.1 - 1.5 mm and a length of 1.5 - 3 mm; S3. Carbonization and deposition: Send the blank into a continuous carbonization furnace for carbonization. The whole process of carbonization is protected by nitrogen. The temperature in the furnace is maintained by continuous electric heating. It is heated to 900 °C at a rate of 4 °C / min, and held for 60 min. Then the temperature is adjusted to 700 °C, and benzene with a dosage of 4 wt% of the total amount of the blank and water with a dosage of 4 wt% of the total amount of the blank are added for deposition. The whole process is protected by nitrogen. After 2 - 3 h, the deposition ends. After the carbon molecular sieve after deposition is naturally cooled, it is screened by a sealed classifier to obtain a high-compression carbon molecular sieve.

[0029] <Example 1.2> A preparation process of a high-compression carbon molecular sieve, comprising the following steps: S1. Pretreatment of raw materials: Transport the flower mud to a crusher for crushing treatment by a sealed stainless-steel conveyor belt. Take 1 kg of the crushed flower mud and disperse it in 5 L of ethanol with 30 g of tetraethyl orthosilicate. Add a 20 wt% sodium hydroxide solution to adjust the pH of the system to 9 - 10. Heat it to 60 °C and stir and react at a rotation speed of 500 r / min for 30 min. Then heat it to 90 °C at a heating rate of 2 °C / min and stir for 45 min. Cool it, add 6 mol / L hydrochloric acid to adjust the pH in the system to 7, filter out the solid, wash it, and transport it into an electric dryer for drying through a sealed pipeline by pneumatic conveying. The moisture in the raw materials is removed during drying. The drying temperature is 170 °C. Under the beating plate, the material is continuously lifted and scattered in a spiral progressive manner to achieve heat exchange. Dry it until the moisture content is between 0.5 - 5 wt% (the time is within 2 - 3 h). The dried material is transported into a ball mill for ball milling through a sealed pipeline and ground into a fine powder material, controlling the particle size to be 5 - 30 μm to obtain the flower mud powder; S2. Mixing and forming: Mix 350 g of the flower mud powder obtained in step S1, 150 g of liquid phenolic resin, 200 g of binder, and 300 mL of water, add them to a mixer for sealed stirring. The flower mud powder is transported to the mixer in a sealed manner, the liquid phenolic resin is pumped to the mixer through a diaphragm pump in a ton barrel, the binder is directly transported through a storage tank pipeline, the opening of the ton barrel is closed. After being evenly kneaded by the mixer, it is extruded into a blank by a twin-screw extruder, obtaining a blank with a diameter of 1.1 - 1.5 mm and a length of 1.5 - 3 mm; S3, Carbonization and Deposition: Feed the green body into a continuous carbonization furnace for carbonization. Nitrogen is used for protection throughout the carbonization process. The temperature inside the furnace is maintained by continuous electric heating. Heat up to 900 °C at a rate of 4 °C / min, hold for 60 min, then adjust the temperature to 800 °C, add benzene with a dosage of 4 wt% of the total amount of the green body and water with a dosage of 4 wt% of the total amount of the green body for deposition. Nitrogen is used for protection throughout the process. After 2 - 3 h, the deposition ends. After natural cooling, the carbon molecular sieve after deposition is screened by an airtight classifier to obtain a high compressive strength carbon molecular sieve.

[0030] <Example 2.1> A preparation process of a high compressive strength carbon molecular sieve, different from Example 1.1 in that in step S1, the dosage of tetraethyl orthosilicate is 17.5 g, and the rest are the same as in Example 1.1.

[0031] <Example 2.2> A preparation process of a high compressive strength carbon molecular sieve, different from Example 1.1 in that in step S1, the dosage of tetraethyl orthosilicate is 20 g, and the rest are the same as in Example 1.1.

[0032] <Example 2.3> A preparation process of a high compressive strength carbon molecular sieve, different from Example 1.1 in that in step S1, the dosage of tetraethyl orthosilicate is 22.5 g, and the rest are the same as in Example 1.1.

[0033] <Example 2.4> A preparation process of a high compressive strength carbon molecular sieve, different from Example 1.1 in that in step S1, the dosage of tetraethyl orthosilicate is 25 g, and the rest are the same as in Example 1.1.

[0034] <Example 2.5> A preparation process of a high compressive strength carbon molecular sieve, different from Example 1.1 in that in step S1, the dosage of tetraethyl orthosilicate is 27.5 g, and the rest are the same as in Example 1.1.

[0035] <Example 3.1> A preparation process of a high compressive strength carbon molecular sieve, different from Example 1.1 in that in step S2, the dosage of the flower mud powder obtained in step S1 is 365 g, and the dosage of liquid phenolic resin is 135 g, and the rest are the same as in Example 1.1.

[0036] <Example 3.2> A preparation process of a high compressive strength carbon molecular sieve, which is different from Example 1.1 in that in step S2, the amount of the flower mud powder obtained in step S1 is 375 g, and the amount of the liquid phenolic resin is 125 g, and the rest are the same as those in Example 1.1.

[0037] <Example 3.3> A preparation process of a high compressive strength carbon molecular sieve, which is different from Example 1.1 in that in step S2, the amount of the flower mud powder obtained in step S1 is 390 g, and the amount of the liquid phenolic resin is 110 g, and the rest are the same as those in Example 1.1.

[0038] <Example 4.1> A preparation process of a high compressive strength carbon molecular sieve, which is different from Example 1.1 in that in step S3, the specific operation of carbonization is: heating up to 700 °C at a rate of 5 °C / min, holding for 30 min for the first-stage carbonization, then heating up to 1000 °C at a rate of 2 °C / min, holding for 30 min for the second-stage carbonization, and the rest are the same as those in Example 1.1.

[0039] <Example 4.2> A preparation process of a high compressive strength carbon molecular sieve, which is different from Example 1.1 in that in step S3, the specific operation of carbonization is: heating up to 600 °C at a rate of 2 °C / min, holding for 60 min for the first-stage carbonization, then heating up to 800 °C at a rate of 1 °C / min, holding for 60 min for the second-stage carbonization, and the rest are the same as those in Example 1.1.

[0040] <Example 4.3> A preparation process of a high compressive strength carbon molecular sieve, which is different from Example 1.1 in that in step S3, the specific operation of carbonization is: heating up to 650 °C at a rate of 3.5 °C / min, holding for 50 min for the first-stage carbonization, then heating up to 900 °C at a rate of 1.5 °C / min, holding for 40 min for the second-stage carbonization, and the rest are the same as those in Example 1.1.

[0041] <Example 5.1> A preparation process of a high compressive strength carbon molecular sieve, which is different from Example 4.3 in that a mixed gas is also introduced in the second-stage carbonization, and the specific operation is: introducing a mixed gas composed of carbon dioxide and water vapor with a volume ratio of 1:1 at an introduction rate of 60 mL / g / min, and the rest are the same as those in Example 4.3.

[0042] <Example 5.2> A preparation process of a high-compressive carbon molecular sieve, which is different from Example 4.3 in that a mixed gas is also introduced during the secondary carbonization. The specific operation is as follows: A mixed gas composed of carbon dioxide and water vapor with a volume ratio of 2:1 is introduced at an introduction rate of 60 mL / g / min, and the rest is the same as in Example 4.3.

[0043] <Example 5.3> A preparation process of a high-compressive carbon molecular sieve, which is different from Example 4.3 in that a mixed gas is also introduced during the secondary carbonization. The specific operation is as follows: A mixed gas composed of carbon dioxide and water vapor with a volume ratio of 2.5:1 is introduced at an introduction rate of 60 mL / g / min, and the rest is the same as in Example 4.3.

[0044] <Example 5.4> A preparation process of a high-compressive carbon molecular sieve, which is different from Example 4.3 in that a mixed gas is also introduced during the secondary carbonization. The specific operation is as follows: A mixed gas composed of carbon dioxide and water vapor with a volume ratio of 3:1 is introduced at an introduction rate of 60 mL / g / min, and the rest is the same as in Example 4.3.

[0045] <Example 5.5> A preparation process of a high-compressive carbon molecular sieve, which is different from Example 4.3 in that a mixed gas is also introduced during the secondary carbonization. The specific operation is as follows: A mixed gas composed of carbon dioxide and water vapor with a volume ratio of 4:1 is introduced at an introduction rate of 60 mL / g / min, and the rest is the same as in Example 4.3.

[0046] <Example 5.6> A preparation process of a high-compressive carbon molecular sieve, which is different from Example 4.3 in that a mixed gas is also introduced during the secondary carbonization. The specific operation is as follows: A mixed gas composed of carbon dioxide and water vapor with a volume ratio of 5:1 is introduced at an introduction rate of 60 mL / g / min, and the rest is the same as in Example 4.3.

[0047] <Example 6.1> A preparation process of a high-compressive carbon molecular sieve, which is different from Example 5.3 in that the introduction rate of the mixed gas is controlled at 30 mL / g / min for the first 20 min of the secondary carbonization and 70 mL / g / min for the last 20 min of the secondary carbonization, and the rest is the same as in Example 5.3.

[0048] <Example 6.2> A preparation process of a high compressive strength carbon molecular sieve, which is different from Example 5.3 in that the feeding rate of the mixed gas is controlled at 35 mL / g / min in the first 20 min of the second-stage carbonization and the feeding rate of the mixed gas is controlled at 75 mL / g / min in the last 20 min of the second-stage carbonization, and the rest is the same as Example 5.3.

[0049] <Example 6.3> A preparation process of a high compressive strength carbon molecular sieve, which is different from Example 5.3 in that the feeding rate of the mixed gas is controlled at 40 mL / g / min in the first 20 min of the second-stage carbonization and the feeding rate of the mixed gas is controlled at 80 mL / g / min in the last 20 min of the second-stage carbonization, and the rest is the same as Example 5.3.

[0050] <Example 7.1> A preparation process of a high compressive strength carbon molecular sieve, which is different from Example 1.1 in that a pulsed current with a frequency of 1 Hz is applied to the system during the carbonization in step S3, and the rest is the same as Example 1.1.

[0051] <Example 7.2> A preparation process of a high compressive strength carbon molecular sieve, which is different from Example 1.1 in that a pulsed current with a frequency of 3 Hz is applied to the system during the carbonization in step S3, and the rest is the same as Example 1.1.

[0052] <Example 7.3> A preparation process of a high compressive strength carbon molecular sieve, which is different from Example 1.1 in that a pulsed current with a frequency of 5 Hz is applied to the system during the carbonization in step S3, and the rest is the same as Example 1.1.

[0053] <Comparative Example 1> Different from Example 1.1, tetraethyl orthosilicate in step S1 is removed. Step S1 is specifically as follows: The flower mud is conveyed to a crusher for crushing by a closed stainless steel conveyor belt, and is pneumatically conveyed into an electric dryer through a closed pipeline for drying to remove the moisture in the raw materials. The drying temperature is 170 °C. Under the action of the plowshare, the materials are continuously lifted and scattered to achieve heat exchange in a spiral progressive manner, and dried to a moisture content between 0.5-5 wt% (within 2-3 h). The dried materials are pneumatically conveyed into a ball mill through a closed pipeline for ball milling to form micro-powdered materials, and the particle size is controlled to be 5-30 um to obtain flower mud powder; the rest is the same as Example 1.1.

[0054] <Comparative Example 2.1> The difference from Example 1.1 is that in step S1, the amount of tetraethyl orthosilicate used is 10 g, and the rest is the same as in Example 1.1.

[0055] <Comparative Example 2.2> The difference from Example 1.1 is that in step S1, the amount of tetraethyl orthosilicate used is 40 g, and the rest is the same as in Example 1.1.

[0056] <Comparative Example 3.1> The difference from Example 1.1 is that in step S2, the amount of the flower mud powder obtained in step S1 used is 300 g, and the amount of liquid phenolic resin used is 200 g, and the rest is the same as in Example 1.1.

[0057] <Comparative Example 3.2> The difference from Example 1.1 is that in step S2, the amount of the flower mud powder obtained in step S1 used is 400 g, and the amount of liquid phenolic resin used is 100 g, and the rest is the same as in Example 1.1.

[0058] <Comparative Example 3.3> The difference from Example 1.1 is that in step S2, the amount of the binder used is 150 g, and the rest is the same as in Example 1.1.

[0059] <Comparative Example 3.4> The difference from Example 1.1 is that in step S2, the amount of the binder used is 250 g, and the rest is the same as in Example 1.1. Performance detection

[0060] Detect the compressive strength (N / particle), bulk density (g / L), air-nitrogen ratio, nitrogen production rate (L / h·kg), and nitrogen concentration (%) of the high compressive strength carbon molecular sieve obtained in the examples and comparative examples. In the detection of the air-nitrogen ratio, nitrogen production rate, and nitrogen concentration, the adsorption pressure is 0.7 - 0.8 MPa, and record the results in Table 1.

[0061] Table 1 Performance detection table

[0062] Data analysis: It can be seen from Table 1 that the compressive strength of the high compressive strength carbon molecular sieve prepared in Examples 1.1 - 1.2 is 105 - 107 N / particle, the bulk density is 668 - 670 g / L, the nitrogen concentration is at the 99.99% level, the nitrogen production rate is 123 - 125 L / h·kg, and the air-nitrogen ratio is 4.6, proving that the high compressive strength carbon molecular sieve of the present application has excellent nitrogen production capacity, high mechanical strength, and low bulk density.

[0063] Examples 2.1 - 2.5 are different from Example 1.1 in that the present application adjusts the addition amount of tetraethyl orthosilicate in step S1. The results show that the compressive strength of the high compressive strength carbon molecular sieve in Example 2.4 is significantly improved, proving that by strictly controlling the weight ratio of the crushed flower mud to tetraethyl orthosilicate, the dosage ratio of the silicon dioxide particles formed by the hydrolysis and condensation of tetraethyl orthosilicate to the flower mud base material can be made more appropriate. Combining with the overall process steps, it helps to finally obtain a high compressive strength carbon molecular sieve with a compressive strength of 110 N / particle.

[0064] Examples 3.1 - 3.3 are different from Example 1.1 in that the present application adjusts the dosage of the flower mud powder and the liquid phenolic resin in step S2. The results show that the nitrogen yield in Example 3.2 is significantly improved, and the air-nitrogen ratio is reduced on the premise that the nitrogen concentration has no obvious change, proving that by strictly controlling the weight ratio of the flower mud powder, the liquid phenolic resin, the binder and water, the structural stability of the carbon molecular sieve is further optimized, ensuring that the micropore proportion in the finally formed carbon molecular sieve is more appropriate.

[0065] Examples 4.1 - 4.3 are different from Example 1.1 in that the present application divides the carbonization into one-stage carbonization and two-stage carbonization, and respectively controls the heating rate, temperature and holding time of the two. The results show that the compressive strength and nitrogen concentration of the high compressive strength carbon molecular sieve in Examples 4.1 - 4.3 are significantly improved, proving that the present application carbonizes the material in two stages and respectively controls different heating rates and holding times, which can make the green body carbonize more fully and evenly, help to form a stable structure, thereby improving the compressive strength of the carbon molecular sieve, reasonably controlling the bulk density, and making both the nitrogen yield and nitrogen production concentration of the carbon molecular sieve at a relatively high level.

[0066] Examples 5.1 - 5.6 are different from Example 4.3 in that the present application also introduces a mixed gas in the two-stage carbonization. The results show that the nitrogen yield of the high compressive strength carbon molecular sieve is significantly improved and the bulk density is greatly reduced, proving that introducing a mixed gas in the two-stage carbonization can selectively etch the amorphous carbon region at high temperature to form a gradient distribution of micropore-mesopore structure, optimize the nitrogen yield and nitrogen production concentration of the carbon molecular sieve, and further reduce its bulk density without affecting the compressive strength of the carbon molecular sieve.

[0067] Compared with other groups in Example 5, Examples 5.3 - 5.4 have a higher nitrogen yield and a lower bulk density, and the nitrogen concentration and air-nitrogen ratio are basically unchanged, proving that by further controlling the ratio of carbon dioxide and water vapor during the two-stage carbonization, the present application helps to further optimize the pore structure and internal composition of the carbon molecular sieve, improve its compressive strength, and reduce the bulk density of the prepared high compressive strength carbon molecular sieve by 20 - 25 g / L.

[0068] Examples 6.1 - 6.3 are different from Example 5.3 in that the present application also controls the gas mixture feeding rate during the second-stage carbonization. In the first half of the time, the gas is fed at a low speed, and in the second half of the time, it is fed at a high speed. The results show that the nitrogen yield of the high-compressive-strength carbon molecular sieve has been significantly improved, the bulk density has been greatly reduced, and the nitrogen concentration and the air-nitrogen ratio have basically remained unchanged. It is proved that by evenly dividing the second-stage carbonization time and controlling the gas mixture feeding rate in stages, the present application helps to further optimize the carbonization process. Feeding the gas mixture slowly can gently initiate the carbonization reaction, allowing the internal structure of the carbon molecular sieve to gradually and stably form a basic framework. Feeding the gas mixture quickly can accelerate the carbonization process and further optimize the pore structure, thus facilitating the preparation of a high-compressive-strength carbon molecular sieve with both high mechanical strength and low bulk density.

[0069] Examples 7.1 - 7.3 are different from Example 1.1 in that during the carbonization in step S3 of the present application, a pulsed current is also applied to the system. The results show that both the compressive strength and the nitrogen yield of the high-compressive-strength carbon molecular sieve have been improved to a certain extent. It is proved that by using a pulsed current as an auxiliary during carbonization, the present application can promote the orderly arrangement of the internal microstructure of the carbon molecular sieve, accelerate the carbonization reaction process, and help to form a more stable and uniform pore structure.

[0070] Comparative Example 1 is different from Example 1.1 in that tetraethyl orthosilicate is removed in the present application. The results show that the compressive strength of the carbon molecular sieve has been greatly reduced, which proves that tetraethyl orthosilicate undergoes a hydrolysis and condensation reaction, and the formed silicon dioxide particles will be relatively evenly distributed in the flower mud base material. The hydroxyl groups on the surface of the silicon dioxide particles will undergo a dehydration condensation reaction with the hydroxymethyl groups on the surface of the flower mud to form Si-O-C covalent bonds, forming a relatively good bonding interface. When the embryo is heated and carbonized, some Si-O-C covalent bonds will form a SiO 2 / C composite skeleton, thereby further enhancing the compressive capacity of the carbon molecular sieve.

[0071] Comparative Examples 2.1 - 2.2 are different from Example 1.1 in that the amount of tetraethyl orthosilicate is adjusted in the present application. The results show that the compressive strength of the carbon molecular sieve has been greatly reduced and the nitrogen concentration has also decreased. It is proved that by strictly controlling the weight ratio of the crushed flower mud to tetraethyl orthosilicate, the dosage ratio of the silicon dioxide particles formed by the hydrolysis and condensation of tetraethyl orthosilicate to the flower mud base material can be made more appropriate. Combining with the overall process steps, it helps to finally obtain a high-compressive-strength carbon molecular sieve with higher compressive strength.

[0072] Comparative Examples 3.1 - 3.4 are different from Example 1.1 in that the present application adjusts the material ratios during kneading. The results show that the compressive strength of the carbon molecular sieves in Comparative Examples 3.1 - 3.2 is significantly reduced, and the nitrogen concentration and nitrogen production rate are also decreased. The compressive strength of the carbon molecular sieve in Comparative Example 3.3 is severely reduced, and the nitrogen production rate in Comparative Example 3.4 is severely reduced. This proves that the present application controls the ratio between the materials here to ensure that the proportion of micropores in the finally formed carbon molecular sieve is appropriate. At the same time, the flower mud powder and liquid phenolic resin are the active precursors of the carbon molecular sieve. Therefore, their proportions directly affect the number of micropores in the carbon molecular sieve. The binder belongs to the "ineffective component". Excessive addition will block the micropores of the carbon molecular sieve, and insufficient addition will lead to poor structural stability of the carbon molecular sieve.

[0073] The examples of this specific implementation mode are all the preferred examples of the present application, and do not limit the protection scope of the present application accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A preparation process of a high-compressive carbon molecular sieve, characterized in that, It includes the following steps: S1. Pretreatment of raw materials: After crushing the flower mud, it is dispersed in ethanol with tetraethyl orthosilicate according to a weight ratio of 100:(1.5 - 3), and stirred and reacted under the condition of pH = 9 - 10. After the reaction, the pH is adjusted to 7, the solid is filtered out, washed, dried, and ball-milled to obtain flower mud powder; S2. Mixing and forming: The flower mud powder, liquid phenolic resin, binder, and water obtained in step S1 are blended according to a weight ratio of (35 - 40):(10 - 15):20:30, stirred, kneaded, extruded, and formed to obtain a green body; S3. Carbonization and deposition: The green body is heated for carbonization, then the temperature is adjusted to 700 - 800 °C, benzene is added for deposition, and after the deposition is completed, it is cooled and screened to obtain a high compressive strength carbon molecular sieve.

2. The preparation process of a highly compressive carbon molecular sieve according to claim 1, wherein, In step S1, after crushing the flower mud, it is dispersed in ethanol with tetraethyl orthosilicate according to a weight ratio of 100:2.

5.

3. The preparation process of a high compressive strength carbon molecular sieve according to claim 1, characterized in that, In step S2, the flower mud powder, liquid phenolic resin, binder, and water obtained in step S1 are blended according to a weight ratio of 37.5:12.5:20:

30.

4. The preparation process of a high compressive strength carbon molecular sieve according to claim 1, characterized in that, In step S3, the specific operation of carbonization is as follows: The temperature is raised to 600 - 700 °C at a rate of 2 - 5 °C / min, held for 30 - 60 min for the first-stage carbonization, and then the temperature is raised to 800 - 1000 °C at a rate of 1 - 2 °C / min, held for 30 - 60 min for the second-stage carbonization.

5. The preparation process of a high compressive strength carbon molecular sieve according to claim 4, characterized in that, In the second-stage carbonization, a mixed gas is also introduced, and the mixed gas includes carbon dioxide and water vapor with a volume ratio of (1 - 5):

1.

6. The preparation process of a high compressive strength carbon molecular sieve according to claim 5, characterized in that, The mixed gas includes carbon dioxide and water vapor with a volume ratio of (2.5 - 3):

1.

7. The preparation process of a high compressive strength carbon molecular sieve according to claim 5, characterized in that, The time of the second-stage carbonization is evenly divided. The feeding rate of the mixed gas is controlled at 30 - 40 mL / g / min in the first stage and 70 - 80 mL / g / min in the second stage.

8. The preparation process of a high compressive strength carbon molecular sieve according to claim 1, characterized in that, In the carbonization of step S3, a pulsed current with a frequency of 1 - 5 Hz is also applied to the system.

9. The preparation process of a high compressive strength carbon molecular sieve according to claim 1, characterized in that, In the deposition of step S3, the dosage of benzene is 4 wt% of the total amount of the green body.

10. A high compressive strength carbon molecular sieve obtained by the preparation process according to any one of claims 1-9, characterized in that, The compressive strength of the high compressive strength carbon molecular sieve is ≥105 N / particle, and the bulk density is ≤670 g / L.

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