Carbon molecular sieve aperture fine trimming process

Abstract

The invention discloses a carbon molecular sieve aperture fine trimming process. The process comprises the following steps: a, preparing raw materials; b, sol preparation; c, curing and forming; d, drying and crushing; e, carbonizing and pyrolyzing; f, activating and chambering; and g, CVD (Chemical Vapor Deposition) fine trimming. According to the present invention, through the flexible ratio regulation and control of the polymer, the micropore pore-forming agent and the mesopore pore-forming agent, and the combination of the soft-hard double-template cooperation, the gradient pyrolysis and the CVD post-treatment technology, the ratio of the micropores to the mesopores can be optimized to 5: 5 or even 4: 6 from the traditional 7: 3, the high selectivity is maintained while the mass transfer efficiency is significantly improved, and the separation performance of the carbon molecular sieve breaks through the existing bottleneck.

Description

Technical Field

[0001] This invention relates to the field of carbon molecular sieves, and more particularly to a process for refining the pore size of carbon molecular sieves. Background Technology

[0002] Traditional carbon molecular sieve manufacturing technology mainly involves crushing, grinding, carbonization, and deposition. The common understanding is that the pore size of carbon molecular sieves is primarily determined by the carbonization process, which is considered crucial to the quality of the sieve. However, the selectivity of carbon molecular sieves is not solely determined by the carbonization process; it is also closely related to the raw material ratio, pyrolysis temperature gradient, atmosphere control, and post-processing. The proportion of polymer compounds in the raw material ratio directly affects the formation of microporous structures during carbonization. Furthermore, the construction of mesopores is not precisely controlled, resulting in a well-developed microporous structure but uneven mesopore distribution, limiting its high selectivity in gas separation. Summary of the Invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art.

[0004] Therefore, the technical solution adopted by the present invention to solve the technical problem is: a carbon molecular sieve pore size refinement process, comprising the following steps: a. Raw material preparation: Weigh the required raw materials according to their mass components, including 60 parts of polymeric carbon source 15 parts of microporous pore-forming agent 20 parts of medium-pore pore-forming agent 5 parts of solidified catalyst 30 parts of solvent 1 part dispersant 20 parts of auxiliary agent; b. Sol preparation: Add solvent, additives and dispersant to the reaction vessel, stir and then add mesoporous pore-forming agent. After dissolving, add microporous pore-forming agent. After dissolving, add polymeric carbon source. Stir thoroughly and then add curing catalyst and continue stirring until cooled to room temperature to obtain solution. c. Solidification and molding: The solution is placed in a spray drying tower, and microspheres are obtained after drying and spraying. d. Drying and pulverizing: After further drying, the microspheres are pulverized in a ball mill to obtain coarse particles; e. Carbonization pyrolysis: The coarse particles are placed in a three-temperature zone tubular furnace for high-temperature pyrolysis; f. Activation and pore expansion: After pyrolysis, the coarse particles are further activated and expanded in a three-temperature zone tubular furnace by adding an activator to obtain the coarse product. g. CVD finishing: The crude product is placed in a CVD tube furnace for finishing to obtain carbon molecular sieve products.

[0005] Preferably, in step a, the high molecular carbon source is phenolic resin, the phenolic resin has a viscosity of 4000-5000 mPa·s at 25°C, the microporous pore-forming agent is anhydrous glucose, the mesoporous pore-forming agent is Pluronic F127, the curing catalyst is oxalic acid, the solvent is anhydrous ethanol, the dispersant is polyvinylpyrrolidone, and the auxiliary agent is deionized water.

[0006] Preferably, anhydrous glucose is ball-milled to a particle size of <50μm and then dried.

[0007] Preferably, in step b, after adding the polymeric carbon source, the temperature is raised to 60°C and stirred continuously for 4 hours at a stirring speed of 300 rpm.

[0008] Preferably, in step c, the inlet temperature of the spray drying tower is 180°C, the outlet temperature is 80-90°C, and the rotation speed of the atomizing disc is 14000 rpm.

[0009] Preferably, in step d, the microspheres are first dried in a drying oven at low temperature, and then placed in a planetary ball mill and ball-milled at 300 rpm for 30 minutes, with the diameter of the coarse particles controlled at 0.5-0.8 mm.

[0010] Preferably, step e includes first deep drying at 120°C under a nitrogen atmosphere for 2–4 hours, then gradually increasing the temperature to 300°C under a nitrogen atmosphere for 2–4 hours to form micropores, then increasing the temperature from 300°C to 600°C at a rate of 1°C per minute while maintaining an oxygen input of 5%–10% of the nitrogen atmosphere, holding the temperature at 600°C for 1 hour and then turning off the oxygen input to maintain stable carbonization of the mesopores under a nitrogen atmosphere, and finally heating to 900°C and holding under a nitrogen atmosphere for 2–4 hours to solidify the structure. At 300°C, the pore-forming agent decomposes and preliminary pores form; at 300–600°C, the mesopores are stabilized and the edge functional groups are modified; at 600–900°C, the carbon skeleton shrinks and the micropores are refined; finally, holding at this temperature achieves structural solidification.

[0011] Preferably, in step f, a carbon dioxide atmosphere is introduced into a three-zone tube furnace and held at 850°C for 2–4 hours to obtain a rough product. Selective etching is then used to seal the holes and improve the connectivity of the intermediate holes.

[0012] Preferably, in step g, the crude product is placed in a CVD tube furnace and heated to 600°C under a nitrogen atmosphere. After reaching 600°C, methane gas is introduced while maintaining the nitrogen atmosphere and held at that temperature for 10–30 minutes. Then, the methane gas input is turned off, and the temperature is reduced to 200°C within 60 minutes. Finally, the product is allowed to cool naturally to room temperature to obtain the carbon molecular sieve product. This reduces excessively large mesopore openings and improves the uniformity of pore size distribution.

[0013] The beneficial effects of this invention are as follows: by flexibly controlling the ratio of polymers, microporous pore-forming agents, and mesoporous pore-forming agents, combined with soft-hard dual-template synergy, gradient pyrolysis, and CVD post-processing technology, the ratio of micropores to mesopores can be optimized from the traditional 7:3 to 5:5 or even 4:6. While maintaining high selectivity, the mass transfer efficiency is significantly improved, enabling the separation performance of carbon molecular sieves to break through existing bottlenecks. This whole-process control approach of "precursor structure design - pyrolysis process control - post-processing refinement" represents a paradigm shift in carbon molecular sieve manufacturing technology from "experience-based carbonization" to "precision construction". Detailed Implementation

[0014] The present invention will be further described below with reference to embodiments, but is not limited to the contents of the specification.

[0015] Example 1: A process for refining the pore size of carbon molecular sieves, comprising the following steps: a. Raw material preparation: Weigh the required raw materials according to their mass components, including 60 parts of polymeric carbon source 15 parts of microporous pore-forming agent 20 parts of medium-pore pore-forming agent 5 parts of solidified catalyst 30 parts of solvent 1 part dispersant 20 parts of auxiliary agent; b. Sol preparation: Add solvent, additives and dispersant to the reaction vessel, stir and then add mesoporous pore-forming agent. After dissolving, add microporous pore-forming agent. After dissolving, add polymeric carbon source. Stir thoroughly and then add curing catalyst and continue stirring until cooled to room temperature to obtain solution. c. Solidification and molding: The solution is placed in a spray drying tower, and microspheres are obtained after drying and spraying. d. Drying and pulverizing: After further drying, the microspheres are pulverized in a ball mill to obtain coarse particles; e. Carbonization pyrolysis: The coarse particles are placed in a three-temperature zone tubular furnace for high-temperature pyrolysis; f. Activation and pore expansion: After pyrolysis, the coarse particles are further activated and expanded in a three-temperature zone tubular furnace by adding an activator to obtain the coarse product. g. CVD finishing: The crude product is placed in a CVD tube furnace for finishing to obtain carbon molecular sieve products.

[0016] In step a, the high molecular carbon source is phenolic resin, which has a viscosity of 4000-5000 mPa·s at 25°C. The microporous pore-forming agent is anhydrous glucose, the mesoporous pore-forming agent is Pluronic F127, the curing catalyst is oxalic acid, the solvent is anhydrous ethanol, the dispersant is polyvinylpyrrolidone, and the auxiliary agent is deionized water.

[0017] Anhydrous glucose was ball-milled to a particle size of <50μm and then dried.

[0018] After adding the polymeric carbon source in step b, the temperature is raised to 60°C and stirred continuously for 4 hours at a stirring speed of 300 rpm.

[0019] In step c, the inlet temperature of the spray drying tower is 180℃, the outlet temperature is 80~90℃, and the rotation speed of the atomizing disc is 14000rpm.

[0020] In step d, the microspheres are first dried in a drying oven at low temperature, and then placed in a planetary ball mill and ball-milled at 300 rpm for 30 minutes. The diameter of the coarse particles is controlled at 0.5-0.8 mm.

[0021] Step e includes first drying at 120°C under a nitrogen atmosphere for 2-4 hours, then gradually increasing the temperature to 300°C under a nitrogen atmosphere for 2-4 hours to form micropores, then increasing the temperature from 300°C to 600°C at a rate of 1°C per minute while maintaining an oxygen input of 5%-10% of the nitrogen intake under a nitrogen atmosphere, then holding the temperature at 600°C for 1 hour and turning off the oxygen input to maintain stable carbonization of the mesopores under a nitrogen atmosphere, and finally heating to 900°C and holding under a nitrogen atmosphere for 2-4 hours to solidify the structure.

[0022] In step f, a carbon dioxide atmosphere is introduced into a three-temperature zone tubular furnace and kept at 850°C for 2 to 4 hours to obtain the crude product.

[0023] In step g, the crude product is placed in a CVD tube furnace and heated to 600°C under a nitrogen atmosphere. After heating to 600°C, methane gas is introduced while maintaining the nitrogen atmosphere and the temperature is held for 10-30 minutes. Then, the methane gas input is turned off and the temperature is reduced to 200°C within 60 minutes. Finally, the product is naturally cooled to room temperature to obtain the carbon molecular sieve product.

[0024] This carbon molecular sieve product has a micropore volume of 0.30–0.40 cm³ / g, a mesopore volume of 0.20–0.35 cm³ / g, a mesopore ratio of 40–55%, and a pore size distribution half-peak width of <1.2 nm.

[0025] The above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is impossible to exhaustively list all embodiments here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A process for refining the pore size of carbon molecular sieves, characterized in that: Includes the following steps: a. Raw material preparation: Weigh the required raw materials according to their mass components, including 60 parts of polymeric carbon source 15 parts of microporous pore-forming agent 20 parts of medium-pore pore-forming agent 5 parts of solidified catalyst 30 parts of solvent 1 part dispersant 20 parts of auxiliary agent; b. Sol preparation: Add solvent, additives and dispersant to the reaction vessel, stir and then add mesoporous pore-forming agent. After dissolving, add microporous pore-forming agent. After dissolving, add polymeric carbon source. Stir thoroughly and then add curing catalyst and continue stirring until cooled to room temperature to obtain solution. c. Solidification and molding: The solution is placed in a spray drying tower, and microspheres are obtained after drying and spraying. d. Drying and pulverizing: After further drying, the microspheres are pulverized in a ball mill to obtain coarse particles; e. Carbonization pyrolysis: The coarse particles are placed in a three-temperature zone tubular furnace for high-temperature pyrolysis; f. Activation and pore expansion: After pyrolysis, the coarse particles are further activated and expanded in a three-temperature zone tubular furnace by adding an activator to obtain the coarse product. g. CVD finishing: The crude product is placed in a CVD tube furnace for finishing to obtain carbon molecular sieve products.

2. The carbon molecular sieve pore size refinement process according to claim 1, characterized in that: In step a, the high molecular carbon source is phenolic resin, the microporous pore-forming agent is anhydrous glucose, the mesoporous pore-forming agent is Pluronic F127, the curing catalyst is oxalic acid, the solvent is anhydrous ethanol, the dispersant is polyvinylpyrrolidone, and the auxiliary agent is deionized water.

3. The carbon molecular sieve pore size refinement process according to claim 2, characterized in that: The anhydrous glucose was ball-milled to a particle size of <50μm and then dried.

4. The carbon molecular sieve pore size refinement process according to claim 1, characterized in that: In step b, after adding the polymeric carbon source, the temperature is raised to 60°C and stirred continuously for 4 hours at a stirring speed of 300 rpm.

5. The carbon molecular sieve pore size refinement process according to claim 1, characterized in that: In step c, the inlet temperature of the spray drying tower is 180℃, the outlet temperature is 80~90℃, and the rotation speed of the atomizing disc is 14000rpm.

6. The carbon molecular sieve pore size refinement process according to claim 1, characterized in that: In step d, the microspheres are first dried in a drying oven at low temperature, and then placed in a planetary ball mill and ball-milled at 300 rpm for 30 minutes, with the diameter of the coarse particles controlled at 0.5-0.8 mm.

7. The carbon molecular sieve pore size refinement process according to claim 1, characterized in that: Step e includes first drying at 120°C under a nitrogen atmosphere for 2-4 hours, then gradually increasing the temperature to 300°C under a nitrogen atmosphere for 2-4 hours to form micropores, then increasing the temperature from 300°C to 600°C at a rate of 1°C per minute while maintaining an oxygen input of 5%-10% of the nitrogen intake under a nitrogen atmosphere, maintaining a constant temperature of 600°C for 1 hour and turning off the oxygen input to maintain stable carbonization of the mesopores under a nitrogen atmosphere, and finally heating to 900°C and maintaining a nitrogen atmosphere for 2-4 hours to solidify the structure.

8. The carbon molecular sieve pore size refinement process according to claim 7, characterized in that: In step f, a carbon dioxide atmosphere is introduced into a three-temperature zone tubular furnace and kept at 850°C for 2 to 4 hours to obtain a crude product.

9. The carbon molecular sieve pore size refinement process according to claim 1, characterized in that: In step g, the crude product is placed in a CVD tube furnace and heated to 600°C under a nitrogen atmosphere. After heating to 600°C, methane gas is introduced while maintaining the nitrogen atmosphere and kept at that temperature for 10-30 minutes. Then, the methane gas input is turned off and the temperature is reduced to 200°C within 60 minutes. Finally, the product is naturally cooled to room temperature to obtain the carbon molecular sieve product.