A high-pressure carbon molecular sieve and its preparation process

Abstract

The present application relates to the field of carbon molecular sieves, and specifically discloses a high-compression carbon molecular sieve and its preparation process. A preparation process for a high-compression carbon molecular sieve comprises the following steps: S1. Raw material pretreatment: crush the flower mud and disperse it in ethanol with ethyl orthosilicate in a weight ratio of 100:(1.5-3), stir and react under pH=9-10, adjust the pH to 7 after the reaction, filter, wash, dry, and ball mill to obtain flower mud powder; S2. Mixing and molding: blend the flower mud powder, liquid phenolic resin, binder and water, stir, knead, extrude, and mold to obtain a blank; S3. Carbonization and precipitation: heat the blank for carbonization, then increase the temperature, add benzene for precipitation, cool, and sieve to obtain a high-compression carbon molecular sieve. The high-compression carbon molecular sieve of the present application has a compressive strength of ≥105N / particle and a bulk density of ≤670g / L, and has excellent nitrogen production capacity, high mechanical strength and low bulk density.

Description

Technical Field

[0001] The present application relates to the technical field of carbon molecular sieves, and in particular to a high-compression-resistant carbon molecular sieve and a preparation process thereof. Background Art

[0002] Carbon molecular sieves, with their unique pore structure and surface chemical properties, demonstrate significant value in numerous fields. In gas separation, they can efficiently separate different types of gases, improving gas purity and providing high-quality feedstock for chemical production. In catalysis, their unique surface properties can serve as catalyst supports, enhancing the efficiency and selectivity of catalytic reactions. In energy storage, they also facilitate the development of new energy storage materials. With the continuous advancement of science and technology, the performance requirements for carbon molecular sieves are also increasing, and their application prospects in various fields are very broad.

[0003] In the preparation of traditional carbon molecular sieves, a common method is to achieve it through polymer or biomass carbonization. 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 attracted widespread attention due to their low cost and renewability. However, there are common problems in the biomass carbonization process, such as large volume shrinkage after carbonization, which will lead to poor structural stability and uneven pore structure, which affects its performance in processes such as gas adsorption and separation. In order to improve these situations, chemical activation or physical activation methods are often used in the existing technology to optimize the pore structure. Chemical activation generally uses specific chemical reagents to react with carbon materials to form more pores; physical activation uses physical means such as high temperature and gas atmosphere to change the structure of carbon materials and increase porosity.

[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, the present application provides a high-compression-resistant carbon molecular sieve and a preparation process thereof.

[0006] In the first aspect, the present application provides a preparation process for a high-compression carbon molecular sieve, comprising the following steps: S1, raw material pretreatment: crush the flower mud and disperse it in ethanol with ethyl orthosilicate in a weight ratio of 100: (1.5-3), stir and react under pH = 9-10, adjust the pH to 7 after the reaction, filter out the solid, wash, dry, and ball mill to obtain flower mud powder; S2, mixing and molding: 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 molded to obtain a blank; S3, carbonization and deposition: heat the blank for carbonization, then adjust the temperature to 700-800°C, add benzene for deposition, cool after deposition, and sieve to obtain a high-compression carbon molecular sieve.

[0007] By adopting the above technical solution, the present application firstly blends floral mud with ethyl orthosilicate, adjusts the pH of the system to alkaline, causes ethyl orthosilicate to undergo hydrolysis and condensation reaction, and the formed silica particles are relatively evenly distributed in the floral mud base material. The hydroxyl groups on the surface of the silica particles react with the hydroxymethyl groups on the surface of the floral mud to undergo dehydration condensation reaction to form Si-OC covalent bonds, forming a relatively good bonding interface; then, the present application blends the floral mud powder obtained after ethyl orthosilicate modification and post-treatment with liquid phenolic resin, binder and water. Stirring, kneading, extruding, and molding to obtain an embryo body. The present application controls the ratio between the materials to ensure that the micropore ratio in the final carbon molecular sieve is more appropriate. At the same time, the flower mud powder and the liquid phenolic resin are active precursors of the carbon molecular sieve, so the ratio of the two directly affects the number of micropores in the carbon molecular sieve. The binder is an "ineffective component". Excessive addition will block the micropores of the carbon molecular sieve, and insufficient addition will cause the structural stability of the carbon molecular sieve to deteriorate. Finally, the present application heats the embryo body for carbonization, and some Si-OC covalent bonds will form SiO 2 / C composite skeleton, in order to further improve the compressive ability of the carbon molecular sieve, and then add benzene for deposition and pore making, and then cool and screen to obtain a high-compression carbon molecular sieve with both high mechanical strength and low bulk density. After testing, its compressive strength is ≥105N / particle, and its bulk density is ≤670g / L. In addition, the main raw material of the high-compression carbon molecular sieve of the present application is flower mud. The product quality of the carbon molecular sieve with high flower mud content is more stable and has a longer service life. Compared with carbon molecular sieves with other substances as the base material, the carbon molecular sieve of the present application has a lower empty nitrogen ratio and a higher nitrogen yield, and has both excellent nitrogen production capacity and good mechanical stability.

[0008] Preferably, in step S1, the flower mud is crushed and dispersed in ethanol with ethyl orthosilicate at a weight ratio of 100:2.5.

[0009] By adopting the above-mentioned technical solution, the present application strictly controls the weight ratio of the crushed flower mud to tetraethyl orthosilicate, which can make the usage ratio of silica particles formed by hydrolysis and condensation of tetraethyl orthosilicate to the flower mud base material more suitable. Combined with the overall process steps, it helps to finally obtain a high-compression carbon molecular sieve with a compressive strength of up to 110N / particle.

[0010] Preferably, in step S2, the flower mud powder obtained in step S1, the liquid phenolic resin, the binder and the water 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 flower mud powder, liquid phenolic resin, binder and water, further optimizes the structural stability of the carbon molecular sieve, and ensures that the proportion of micropores in the final carbon molecular sieve is more appropriate.

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

[0013] By adopting the above-mentioned technical solution, the present application divides the material into two stages for carbonization, and controls different heating rates and holding times respectively, which can make the green body more fully and evenly carbonized, help to form a stable structure, thereby improving the compressive strength of the carbon molecular sieve, reasonably controlling the packing density, and making the nitrogen production and nitrogen concentration of the carbon molecular sieve at a high level.

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

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

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

[0017] By adopting the above technical solution, the present application further controls the mixed gas of carbon dioxide and water vapor to 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-compression carbon molecular sieve by 20-25g / L.

[0018] Preferably, the time of the two carbonization stages is evenly divided, and the introduction rate of the mixed gas is controlled to be 30-40 mL / g / min during the first stage, and the introduction rate of the mixed gas is controlled to be 70-80 mL / g / min during the second stage.

[0019] By adopting the above technical solution, the present application divides the carbonization time into two stages and then controls the rate of introduction of the mixed gas in stages, which helps to further optimize the carbonization process. The mixed gas is first introduced slowly at a rate of 30-40mL / g / min, which can start the carbonization reaction gently and allow the internal structure of the carbon molecular sieve to gradually stabilize and form a basic framework; then the mixed gas is quickly introduced at a rate of 70-80mL / g / min, which can accelerate the carbonization process and further optimize the pore structure, thereby facilitating the preparation of a high-compression carbon molecular sieve with both high mechanical strength and low bulk density.

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

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

[0022] Preferably, in the deposition of step S3, the amount of benzene used is 4 wt % of the total amount of the embryo.

[0023] By adopting the above technical solution, the present application accurately controls the amount of benzene to be deposited at 4wt% of the total amount of the embryo, which helps to form a suitable pore structure on the embryo after carbonization, optimize the pore structure, and thus optimize the nitrogen production and nitrogen concentration of the carbon molecular sieve.

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

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

[0026] In summary, this application has the following beneficial technical effects:

[0027] 1. The preparation process of this application blends floral mud with ethyl orthosilicate and controls the pH reaction, allowing silica particles to be evenly distributed in the floral mud base and form covalent bonds, thereby enhancing the material bonding strength. Furthermore, this application precisely controls the material ratio, ensuring a more reasonable proportion of carbon molecular sieve micropores, ensuring structural stability and unobstructed micropores.

[0028] 2. The carbon molecular sieve of this application is mainly made of floral mud. The carbon molecular sieve with a high floral mud content has more stable product quality and a longer service life. Compared with carbon molecular sieves based on other materials, the carbon molecular sieve of this application has a lower air-to-nitrogen ratio and a higher nitrogen yield, and has both excellent nitrogen production capacity and good mechanical stability.

[0029] 3. The high-compression carbon molecular sieve of the present application has high compressive strength and low bulk density, with compressive strength ≥105N / particle and bulk density ≤670g / L, which solves the problem that the existing preparation method is difficult to achieve both high mechanical strength and low bulk density. DETAILED DESCRIPTION

[0030] Material Source

[0031] Unless otherwise specified, the raw materials used in this application are all commercially available products, specifically:

[0032] Flower mud, carbon content 75-80wt%;

[0033] The present application is further described in detail below with reference to the following examples and comparative examples.

[0034] <Example 1.1>

[0035] A process for preparing a high-compression carbon molecular sieve comprises the following steps:

[0036] S1. Raw material pretreatment: The floral mud was conveyed to a crusher using a closed stainless steel conveyor belt for crushing. 1 kg of crushed floral mud and 15 g of ethyl orthosilicate were dispersed in 5 L of ethanol. 20 wt% sodium hydroxide solution was added to adjust the pH of the system to 9-10. The mixture was heated to 60 ° C and stirred at a speed of 500 r / min for 30 minutes. The mixture was then heated to 90 ° C at a heating rate of 2 ° C / min, stirred for 45 minutes, cooled, and 6 mol / L hydrochloric acid was added to adjust the pH of the system to 9-10. H=7, filter out the solid, wash it, and then pneumatically convey it through a closed pipe into an electric dryer for drying. Drying removes moisture from the raw material. The drying temperature is 170°C. The material is continuously scooped up and scattered in a spiral motion under the lifting plate to achieve heat exchange. Dry it to a moisture content between 0.5-5wt% (within 2-3 hours). The dried material is pneumatically conveyed through a closed pipe into a ball mill for ball milling. After ball milling, it is ground into a micronized material with a controlled particle size of 5-30μm to obtain flower mud powder.

[0037] S2, mixing and molding: 400 g of the flower mud powder obtained in step S1, 100 g of liquid phenolic resin, 200 g of a binder, and 300 mL of water were blended and added to a blender for closed stirring. The flower mud powder was conveyed to the blender in a closed manner, the liquid phenolic resin was pumped into the blender by a diaphragm pump in a ton barrel, and the binder was directly conveyed through a storage tank pipeline. The opening of the ton barrel was sealed, and after being uniformly kneaded in the blender, it was extruded into an embryo with a diameter of 1.1-1.5 mm and a length of 1.5-3 mm.

[0038] S3. Carbonization and deposition: The blank is sent to a continuous carbonization furnace for carbonization. Nitrogen is used for protection during the entire carbonization process. The temperature in the furnace is maintained by electric continuous heating. The temperature is raised to 900°C at a rate of 4°C / min and kept warm for 60 minutes. The temperature is then adjusted to 700°C. Benzene in an amount of 4wt% of the total amount of the blank and water in an amount of 4wt% of the total amount of the blank are added for deposition. Nitrogen is used for protection during the entire process. The deposition is completed after 2-3 hours. After the deposition is completed, the carbon molecular sieve is naturally cooled and sieved through a closed separator to obtain a high-compression carbon molecular sieve.

[0039] <Example 1.2>

[0040] A process for preparing a high-compression carbon molecular sieve comprises the following steps:

[0041] S1. Raw material pretreatment: The floral mud was conveyed to a crusher using a closed stainless steel conveyor belt for crushing. 1 kg of crushed floral mud and 30 g of ethyl orthosilicate were dispersed in 5 L of ethanol. 20 wt% sodium hydroxide solution was added to adjust the pH of the system to 9-10. The mixture was heated to 60 ° C and stirred at a speed of 500 r / min for 30 minutes. The mixture was then heated to 90 ° C at a heating rate of 2 ° C / min, stirred for 45 minutes, cooled, and 6 mol / L hydrochloric acid was added to adjust the pH of the system to 9-10. H=7, filter out the solid, wash it, and then pneumatically convey it through a closed pipe into an electric dryer for drying. Drying removes moisture from the raw material. The drying temperature is 170°C. The material is continuously scooped up and scattered in a spiral motion under the lifting plate to achieve heat exchange. Dry it to a moisture content between 0.5-5wt% (within 2-3 hours). The dried material is pneumatically conveyed through a closed pipe into a ball mill for ball milling. After ball milling, it is ground into a micronized material with a controlled particle size of 5-30μm to obtain flower mud powder.

[0042] S2, mixing and molding: 350g of the flower mud powder obtained in step S1, 150g of liquid phenolic resin, 200g of a binder, and 300mL of water were blended and added to a blender for closed stirring. The flower mud powder was conveyed to the blender in a closed manner, the liquid phenolic resin was pumped into the blender by a diaphragm pump in a ton barrel, and the binder was directly conveyed through a storage tank pipeline. The opening of the ton barrel was sealed, and the mixture was evenly kneaded in the blender and then extruded into an embryo with a diameter of 1.1-1.5mm and a length of 1.5-3mm.

[0043] S3. Carbonization and deposition: The blank is sent to a continuous carbonization furnace for carbonization. Nitrogen is used for protection during the entire carbonization process. The temperature in the furnace is maintained by electric continuous heating. The temperature is raised to 900°C at a rate of 4°C / min and kept warm for 60 minutes. The temperature is then adjusted to 800°C. Benzene in an amount of 4wt% of the total amount of the blank and water in an amount of 4wt% of the total amount of the blank are added for deposition. Nitrogen is used for protection during the entire process. The deposition is completed after 2-3 hours. After the deposition is completed, the carbon molecular sieve is naturally cooled and sieved through a closed separator to obtain a high-compression carbon molecular sieve.

[0044] <Example 2.1>

[0045] A preparation process of a high-compression-resistant carbon molecular sieve is different from that of Example 1.1 in that, in step S1, the amount of ethyl orthosilicate used is 17.5 g, and the rest is the same as that of Example 1.1.

[0046] <Example 2.2>

[0047] A preparation process of a high-compression-resistant carbon molecular sieve is different from that of Example 1.1 in that, in step S1, the amount of ethyl orthosilicate used is 20 g, and the rest is the same as that of Example 1.1.

[0048] <Example 2.3>

[0049] A preparation process of a high-compression-resistant carbon molecular sieve is different from that of Example 1.1 in that, in step S1, the amount of ethyl orthosilicate used is 22.5 g, and the rest is the same as that of Example 1.1.

[0050] <Example 2.4>

[0051] A preparation process of a high-compression-resistant carbon molecular sieve is different from that of Example 1.1 in that, in step S1, the amount of ethyl orthosilicate used is 25 g, and the rest is the same as that of Example 1.1.

[0052] <Example 2.5>

[0053] A preparation process of a high-compression-resistant carbon molecular sieve is different from that of Example 1.1 in that, in step S1, the amount of ethyl orthosilicate used is 27.5 g, and the rest is the same as that of Example 1.1.

[0054] <Example 3.1>

[0055] A preparation process of a high-compression-resistant carbon molecular sieve, which is different from Example 1.1 in that, in step S2, the amount of flower mud powder obtained in step S1 is 365g, and the amount of liquid phenolic resin is 135g, and the rest is the same as Example 1.1.

[0056] <Example 3.2>

[0057] A preparation process of a high-compression-resistant carbon molecular sieve, which is different from Example 1.1 in that, in step S2, the amount of flower mud powder obtained in step S1 is 375 g, and the amount of liquid phenolic resin is 125 g, and the rest is the same as Example 1.1.

[0058] <Example 3.3>

[0059] A preparation process of a high-compression-resistant carbon molecular sieve, which is different from Example 1.1 in that, in step S2, the amount of flower mud powder obtained in step S1 is 390 g, and the amount of liquid phenolic resin is 110 g, and the rest is the same as Example 1.1.

[0060] <Example 4.1>

[0061] A preparation process for a high-compression carbon molecular sieve, which differs from Example 1.1 in that, in step S3, the specific operation of carbonization is: heating to 700°C at a rate of 5°C / min, keeping warm for 30 minutes, and performing a first-stage carbonization, and then heating to 1000°C at a rate of 2°C / min, keeping warm for 30 minutes, and performing a second-stage carbonization. The rest is the same as Example 1.1.

[0062] <Example 4.2>

[0063] A preparation process for a high-compression carbon molecular sieve, which differs from Example 1.1 in that, in step S3, the specific operation of carbonization is: heating to 600°C at a rate of 2°C / min, keeping warm for 60 minutes, and performing a first-stage carbonization, and then heating to 800°C at a rate of 1°C / min, keeping warm for 60 minutes, and performing a second-stage carbonization. The rest is the same as Example 1.1.

[0064] <Example 4.3>

[0065] A preparation process for a high-compression carbon molecular sieve, which differs from Example 1.1 in that, in step S3, the specific operation of carbonization is: heating to 650°C at a rate of 3.5°C / min, keeping warm for 50 minutes, and performing a first-stage carbonization, and then heating to 900°C at a rate of 1.5°C / min, keeping warm for 40 minutes, and performing a second-stage carbonization. The rest is the same as Example 1.1.

[0066] <Example 5.1>

[0067] A preparation process for a high-compression carbon molecular sieve, which differs from Example 4.3 in that a mixed gas is also introduced into the second-stage carbonization. The specific operation is as follows: a mixed gas consisting of carbon dioxide and water vapor in a volume ratio of 1:1 is introduced at an introduction rate of 60 mL / g / min. The rest is the same as Example 4.3.

[0068] <Example 5.2>

[0069] A preparation process for a high-compression carbon molecular sieve, which differs from Example 4.3 in that a mixed gas is also introduced into the second-stage carbonization. The specific operation is: a mixed gas consisting of carbon dioxide and water vapor with a volume ratio of 2:1 is introduced at an introduction rate of 60 mL / g / min. The rest is the same as Example 4.3.

[0070] <Example 5.3>

[0071] A preparation process for a high-compression carbon molecular sieve, which differs from Example 4.3 in that a mixed gas is also introduced into the second-stage carbonization. The specific operation is: a mixed gas consisting 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. The rest is the same as Example 4.3.

[0072] <Example 5.4>

[0073] A preparation process for a high-compression carbon molecular sieve, which differs from Example 4.3 in that a mixed gas is also introduced into the second-stage carbonization. The specific operation is: a mixed gas consisting of carbon dioxide and water vapor with a volume ratio of 3:1 is introduced at an introduction rate of 60 mL / g / min. The rest is the same as Example 4.3.

[0074] <Example 5.5>

[0075] A preparation process for a high-compression carbon molecular sieve, which differs from Example 4.3 in that a mixed gas is also introduced into the second-stage carbonization. The specific operation is: a mixed gas consisting of carbon dioxide and water vapor with a volume ratio of 4:1 is introduced at an introduction rate of 60 mL / g / min. The rest is the same as Example 4.3.

[0076] <Example 5.6>

[0077] A preparation process for a high-compression carbon molecular sieve, which differs from Example 4.3 in that a mixed gas is also introduced into the second-stage carbonization. The specific operation is as follows: a mixed gas consisting of carbon dioxide and water vapor with a volume ratio of 5:1 is introduced at an introduction rate of 60 mL / g / min. The rest is the same as Example 4.3.

[0078] <Example 6.1>

[0079] A preparation process of a high-compression-resistant carbon molecular sieve, which differs from Example 5.3 in that the introduction rate of the mixed gas is controlled to be 30 mL / g / min in the first 20 minutes of the second-stage carbonization, and the introduction rate of the mixed gas is controlled to be 70 mL / g / min in the last 20 minutes of the second-stage carbonization, and the rest is the same as Example 5.3.

[0080] <Example 6.2>

[0081] A preparation process of a high-compression-resistant carbon molecular sieve, which differs from Example 5.3 in that the introduction rate of the mixed gas is controlled to be 35 mL / g / min in the first 20 minutes of the second-stage carbonization, and the introduction rate of the mixed gas is controlled to be 75 mL / g / min in the last 20 minutes of the second-stage carbonization, and the rest is the same as Example 5.3.

[0082] <Example 6.3>

[0083] A preparation process of a high-compression carbon molecular sieve, which differs from Example 5.3 in that the introduction rate of the mixed gas is controlled to be 40 mL / g / min in the first 20 minutes of the second-stage carbonization, and the introduction rate of the mixed gas is controlled to be 80 mL / g / min in the last 20 minutes of the second-stage carbonization, and the rest is the same as Example 5.3.

[0084] <Example 7.1>

[0085] A preparation process of a high-compression-resistant carbon molecular sieve is different from that of Example 1.1 in that, during the carbonization in step S3, a pulse current with a frequency of 1 Hz is also applied to the system, and the rest is the same as that of Example 1.1.

[0086] <Example 7.2>

[0087] A preparation process of a high-compression-resistant carbon molecular sieve is different from that of Example 1.1 in that, during the carbonization in step S3, a pulse current with a frequency of 3 Hz is also applied to the system, and the rest is the same as that of Example 1.1.

[0088] <Example 7.3>

[0089] A preparation process of a high-compression-resistant carbon molecular sieve is different from that of Example 1.1 in that, during the carbonization in step S3, a pulse current with a frequency of 5 Hz is also applied to the system, and the rest is the same as that of Example 1.1.

[0090] <Comparative Example 1>

[0091] The difference from Example 1.1 is that the ethyl orthosilicate in step S1 is removed. Step S1 is specifically as follows: the floral 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 pipe for drying to remove moisture from the raw materials. The drying temperature is 170°C, and the material is continuously picked up and scattered in a spiral motion under the scooping plate to realize heat exchange, and is dried to a moisture content between 0.5-5wt% (within 2-3h). The dried material is pneumatically conveyed into a ball mill through a closed pipe for ball milling treatment, and is ground into a micronized material by ball milling, and the particle size is controlled to be 5-30um to obtain floral mud powder; the rest is the same as Example 1.1.

[0092] <Comparative Example 2.1>

[0093] The difference from Example 1.1 is that in step S1, the amount of ethyl orthosilicate used is 10 g, and the rest is the same as Example 1.1.

[0094] <Comparative Example 2.2>

[0095] The difference from Example 1.1 is that in step S1, the amount of ethyl orthosilicate used is 40 g, and the rest is the same as Example 1.1.

[0096] <Comparative Example 3.1>

[0097] The difference from Example 1.1 is that in step S2, the amount of the flower mud powder obtained in step S1 is 300 g, and the amount of liquid phenolic resin is 200 g. The rest is the same as Example 1.1.

[0098] <Comparative Example 3.2>

[0099] The difference from Example 1.1 is that in step S2, the amount of the flower mud powder obtained in step S1 is 400 g, and the amount of liquid phenolic resin is 100 g. The rest is the same as Example 1.1.

[0100] <Comparative Example 3.3>

[0101] The difference from Example 1.1 is that the amount of binder used in step S2 is 150 g, and the rest is the same as Example 1.1.

[0102] <Comparative Example 3.4>

[0103] The difference from Example 1.1 is that the amount of binder used in step S2 is 250 g, and the rest is the same as Example 1.1.

[0104] Performance testing

[0105] The compressive strength (N / particle), bulk density (g / L), air-to-nitrogen ratio, nitrogen yield (L / h·kg) and nitrogen concentration (%) of the high-compression carbon molecular sieves obtained in the examples and comparative examples were tested. The adsorption pressure in the tests of the air-to-nitrogen ratio, nitrogen yield and nitrogen concentration was 0.7-0.8 MPa, and the results are recorded in Table 1.

[0106] Table 1 Performance test table

[0107]

[0108] Data Analysis:

[0109] As can be seen from Table 1, the compressive strength of the high-compression 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 99.99%, the nitrogen yield is 123-125 L / h·kg, and the air-nitrogen ratio is 4.6, which proves that the high-compression carbon molecular sieve of the present application has excellent nitrogen production capacity, high mechanical strength and low bulk density.

[0110] The difference between Examples 2.1-2.5 and Example 1.1 is that the present application adjusts the amount of tetraethyl orthosilicate added in step S1. The results show that the compressive strength of the high-compression carbon molecular sieve of Example 2.4 is significantly improved, which proves that the present application strictly controls the weight ratio of the crushed floral mud and tetraethyl orthosilicate, so that the amount ratio of silica particles formed by the hydrolysis and condensation of tetraethyl orthosilicate to the floral mud base material can be more suitable. Combined with the overall process steps, it helps to finally obtain a high-compression carbon molecular sieve with a compressive strength of 110N / particle.

[0111] The difference between Examples 3.1-3.3 and Example 1.1 is that the present application adjusts the amount of flower mud powder and liquid phenolic resin in step S2. The results show that the nitrogen yield of Example 3.2 is significantly improved, and the air-nitrogen ratio is also reduced without significant change in nitrogen concentration. This proves that the present application further optimizes the structural stability of the carbon molecular sieve by strictly controlling the weight ratio of flower mud powder, liquid phenolic resin, binder and water, ensuring that the proportion of micropores in the final formed carbon molecular sieve is more appropriate.

[0112] The difference between Examples 4.1-4.3 and Example 1.1 is that the present application divides the carbonization into one-stage carbonization and two-stage carbonization, and controls the heating rate, temperature and holding time of the two respectively. The results show that the compressive strength and nitrogen concentration of the high-compression carbon molecular sieve of Examples 4.1-4.3 are significantly improved, which proves that the present application divides the material into two stages for carbonization and controls different heating rates and holding times respectively, which can make the green body more fully and evenly carbonized, help to form a stable structure, thereby improving the compressive strength of the carbon molecular sieve, reasonably controlling the packing density, and making the nitrogen production and nitrogen concentration of the carbon molecular sieve at a high level.

[0113] The difference between Examples 5.1-5.6 and Example 4.3 is that the present application also introduces a mixed gas during the second-stage carbonization. The results show that the nitrogen yield of the high-compression carbon molecular sieve is significantly improved and the packing density is greatly reduced, which proves that the present application also introduces a mixed gas during the second-stage carbonization, which can selectively etch the amorphous carbon area at high temperature to form a gradient-distributed microporous-mesoporous structure, optimize the nitrogen production and nitrogen concentration of the carbon molecular sieve, and further reduce its packing density without affecting the compressive strength of the carbon molecular sieve.

[0114] Compared with other groups in Example 5, Examples 5.3-5.4 have higher nitrogen yields and lower bulk densities, and the nitrogen concentration and air-nitrogen ratio are basically unchanged, proving that the present application helps to further optimize the pore structure and internal composition of the carbon molecular sieve and improve its compressive strength by further controlling the ratio of carbon dioxide and water vapor during the second-stage carbonization, thereby reducing the bulk density of the prepared high-compression carbon molecular sieve by 20-25 g / L.

[0115] The difference between Examples 6.1-6.3 and Example 5.3 is that the present application also controls the introduction rate of the mixed gas in the two-stage carbonization, with low-speed introduction in the first half and high-speed introduction in the second half. The results show that the nitrogen yield of the high-pressure carbon molecular sieve is significantly improved, the bulk density is greatly reduced, and the nitrogen concentration and the air-nitrogen ratio are basically unchanged. This proves that the present application helps to further optimize the carbonization process by controlling the introduction rate of the mixed gas in stages after dividing the two-stage carbonization time. Slow introduction of the mixed gas can start the carbonization reaction gently, allowing the internal structure of the carbon molecular sieve to gradually stabilize and form a basic framework. Rapid introduction of the mixed gas can accelerate the carbonization process and further optimize the pore structure, which is conducive to the preparation of a high-pressure carbon molecular sieve with both high mechanical strength and low bulk density.

[0116] The difference between Examples 7.1-7.3 and Example 1.1 is that in the carbonization of step S3, a pulse current is also applied to the system. The results show that the compressive strength and nitrogen yield of the high-compression carbon molecular sieve are both improved to a certain extent, proving that the present application can promote the orderly arrangement of the internal microstructure of the carbon molecular sieve, accelerate the carbonization reaction process, and help form a more stable and uniform pore structure by using a pulse current as an auxiliary in the carbonization.

[0117] The difference between Comparative Example 1 and Example 1.1 is that the present application removes the tetraethyl orthosilicate. The results show that the compressive strength of the carbon molecular sieve is greatly reduced, proving that the tetraethyl orthosilicate undergoes a hydrolysis and condensation reaction, and the silica particles formed are more evenly distributed in the floral mud base material. The hydroxyl groups on the surface of the silica particles react with the hydroxymethyl groups on the surface of the floral mud to form Si-OC covalent bonds, forming a relatively good bonding interface. When the embryo is heated and carbonized, some of the Si-OC covalent bonds will form SiO 2 / C composite skeleton, thereby further improving the compressive resistance of carbon molecular sieve.

[0118] The difference between Comparative Examples 2.1-2.2 and Example 1.1 is that the present application adjusts the dosage of ethyl orthosilicate. The results show that the compressive strength of the carbon molecular sieve is greatly reduced, and the nitrogen concentration is also reduced. This proves that the present application strictly controls the weight ratio of the crushed floral mud to ethyl orthosilicate, so that the dosage ratio of the silica particles formed by the hydrolysis and condensation of ethyl orthosilicate to the floral mud base material can be more suitable. Combined with the overall process steps, it helps to finally obtain a high-compressive carbon molecular sieve with higher compressive strength.

[0119] The difference between Comparative Examples 3.1-3.4 and Example 1.1 is that the present application adjusts the ratio of various substances during kneading. The results show that the compressive strength of the carbon molecular sieve of Comparative Examples 3.1-3.2 is greatly reduced, and the nitrogen concentration and nitrogen yield are also reduced. The compressive strength of the carbon molecular sieve of Comparative Example 3.3 is seriously reduced, and the nitrogen yield of Comparative Example 3.4 is seriously reduced, which proves that the present application controls the ratio between the materials to ensure that the proportion of micropores in the final carbon molecular sieve is more appropriate. At the same time, flower mud powder and liquid phenolic resin are active precursors of carbon molecular sieves, so the proportion of the two directly affects the number of micropores in the carbon molecular sieve. The binder is an "invalid component". Excessive addition will clog the micropores of the carbon molecular sieve, and insufficient addition will lead to poor structural stability of the carbon molecular sieve.

[0120] The embodiments of this specific implementation method are all preferred embodiments of the present application and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A process for preparing a high-compression carbon molecular sieve, characterized in that: The following steps are involved: S1. Raw material pretreatment: crush the flower mud and disperse it in ethanol with ethyl orthosilicate in a weight ratio of 100: (1.5-3), stir and react under the condition of pH = 9-10, adjust the pH to 7 after the reaction, filter out the solid, wash, dry, and ball mill to obtain flower mud powder; S2. Mixing and molding: 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, stir, knead, extrude, and mold to obtain an embryo; S3. Carbonization and deposition: heat the embryo to carbonize, then adjust the temperature to 700-800℃, add benzene for deposition, cool after deposition, and sieve to obtain a high-compression carbon molecular sieve; in step S3, the specific operation of carbonization is: heating to 600- 700°C, keep warm for 30-60 minutes, carry out the first stage carbonization, then raise the temperature to 800-1000°C at a rate of 1-2°C / min, keep warm for 30-60 minutes, and carry out the second stage carbonization, during which a mixed gas is also introduced, the mixed gas comprising carbon dioxide and water vapor in a volume ratio of (1-5):1, and the time of the two stages of carbonization is evenly divided, the introduction rate of the mixed gas in the first period is controlled to be 30-40 mL / g / min, and the introduction rate of the mixed gas in the second period is controlled to be 70-80 mL / g / min.

2. The process for preparing a high-compression carbon molecular sieve according to claim 1, characterized in that: In the step S1, the floral mud is crushed and dispersed in ethanol with ethyl orthosilicate in a weight ratio of 100:2.

5.

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

30.

4. The process for preparing a high-compression-resistant carbon molecular sieve according to claim 1, characterized in that: The mixed gas includes carbon dioxide and water vapor in a volume ratio of (2.5-3):

1.

5. The process for preparing a high-compression-resistant carbon molecular sieve according to claim 1, characterized in that: During the carbonization in step S3, a pulse current with a frequency of 1-5 Hz is also applied to the system.

6. The process for preparing a high-compression-resistant carbon molecular sieve according to claim 1, characterized in that: In the deposition of step S3, the amount of benzene used is 4 wt % of the total amount of the embryo.

7. A high-compression-resistant carbon molecular sieve obtained by the preparation process according to any one of claims 1 to 6, characterized in that: The high-compression carbon molecular sieve has a compressive strength of ≥105N / particle and a bulk density of ≤670g / L.

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