Preparation method and application of carbon-based adsorbent with silicon-aluminum molecular sieve as skeleton

Abstract

The application discloses a preparation method and application of a carbon-based adsorbent with a silico-alumina molecular sieve as a skeleton. The method comprises the following steps: (1) immersing the silico-alumina molecular sieve in an alkali solution with a certain concentration for impregnation treatment, and then performing washing, filtration and drying; (2) placing the product in step (1) in a rotary tube furnace, performing programmed temperature heating to a certain temperature under an inert atmosphere, and introducing a proper amount of a carbon source to crack and deposit carbon on the surface of the silico-alumina molecular sieve by a gas phase deposition method, so as to obtain the carbon-based adsorbent with the silico-alumina molecular sieve as the skeleton. The adsorbent is used in a process for separating CH4 / N2 by adopting a pressure swing adsorption method. The application has a high adsorption capacity and CH4 / N2 selectivity for N2 in the application of CH4 / N2 separation by adopting the pressure swing adsorption technology with the composite material as the adsorbent, and has a good industrial application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of adsorbent material preparation and application, and specifically relates to a preparation method and application of a carbon-based adsorbent with a silicon-aluminum molecular sieve as a framework. BACKGROUND

[0002] Energy problems are closely related to the sustainable development of human beings. In view of the current situation of poor oil and gas in China, actively developing and efficiently utilizing low-quality energy is the direction of future energy field development. Coalbed methane is a kind of unconventional clean energy existing in coal seams or coal measures, with CH4 as the main gas component. The key to the development and utilization of coalbed methane lies in the concentration and purification of CH4. When the CH4 concentration is greater than 80%, it can enter the city natural gas network as an efficient fuel; when used as a high-quality chemical raw material, CH4 needs to meet higher concentration requirements.

[0003] The concentration of coalbed methane mainly removes water, nitrogen, oxygen, carbon dioxide, sulfides and heavy carbon hydrogen compounds and other impurities. Due to the similar physical properties of CH4 and N2, the removal of N2 is the most challenging. PSA technology has become the most potential and promising technology for CH4 / N2 separation due to its low energy consumption, large processing capacity, high efficiency, simple equipment and small pollution. The development of high-efficiency adsorbents is the core of PSA technology. The current CH4 / N2 mixed gas separation adsorbents include carbon molecular sieve (CMS), activated carbon (AC), zeolite molecular sieve and MOF material. Each adsorbent material has advantages and disadvantages. Carbon-based adsorbent material is cheap and has developed pore structure, but the pore structure is greatly affected by the type of raw material, the structure is unstable, the pore structure is not uniform, and other problems limit the improvement of its separation selectivity; zeolite molecular sieve has regular pore structure, large specific surface area and good stability. Researchers first systematically studied the CH4 and N2 adsorption performance of conventional molecular sieves, such as 4A, 5A, mordenite and 13X, and found that the equilibrium adsorption amounts of CH4 and N2 are relatively small, which makes it difficult to achieve efficient separation. At present, molecular sieve-based materials still face many problems, such as the highly polarized surface of zeolite molecular sieve preferentially adsorbing CH4, but the diffusion dynamics preferentially adsorbing N2, the existence of competitive adsorption problems; CH4 has a high polarization rate, while N2 has a quadrupole moment, and there are also adsorption contradiction problems on the surface of adsorbents with polar sites; these problems still seriously restrict the industrial application of silicon-aluminum molecular sieves in the direction of methane and nitrogen separation. MOF material has a high separation factor and separation efficiency, but its preparation cost is extremely high and its stability is poor, which is not conducive to the industrial application of large-scale gas purification. In view of the above problems, the carbon-silicon-aluminum molecular sieve composite material is prepared by using silicon-aluminum molecular sieve as the framework and through a carbon deposition modification process. The purpose of improving the N2 adsorption amount and the CH4 / N2 separation coefficient is achieved by combining the characteristics of different materials.

[0004] CN 106693896 B discloses a composite structure adsorbent material for methane adsorption and separation, which uses metal organic framework material as a cladding layer and activated carbon, molecular sieve or mixture of the two as a cladded layer. Although this method has a certain separation effect on CH4 / N2, the raw material cost is high, the preparation process is complex, and the balance separation ratio of CH4 / N2 is not high. CN110354803 B discloses a whole composite porous carbon adsorbent material for separating CH4 / N2, which is prepared by phenol formaldehyde condensation, aging, drying, carbonization and activation. The amount of carbon surface polar sites is adjusted by adjusting the activation time. Since CH4 has a high polarization rate, it will be preferentially adsorbed on the polar sites, thereby realizing the separation of CH4 / N2. However, the surface polar sites of the adsorbent material will form a strong force with CH4, which is not conducive to the desorption of CH4, resulting in low economic efficiency and hindering the industrial application of the adsorbent material. Korean scientists Liu Long of KAIST used MCM-48 ordered mesoporous silica molecular sieve as a hard template, sucrose as a precursor, and sulfuric acid as a catalyst to carbonize sucrose molecules, thereby synthesizing ordered mesoporous carbon material for the first time. However, this carbon material is composed of a small number of partially graphitized amorphous nanocarbon rods or nanowire arrays, and the pore channels are generated by the stacking gap between the rods, so the pore size distribution is relatively wide. In addition, silica-based mesoporous materials are used as templates in the synthesis, and the templates cannot be recycled, and a large amount of acid and alkali is also used as a solvent, which greatly limits its application.

[0005] At present, the research on separating CH4 / N2 by using composite materials as adsorbents by pressure swing adsorption method has made certain progress. In order to further improve the separation effect of CH4 / N2, the construction idea and preparation process of the composite material need to be further improved and perfected. SUMMARY

[0006] The purpose of the present application is to solve the problem of coal bed gas recovery, further improve the adsorption capacity of the adsorbent for N2 and the separation selectivity of CH4 / N2, and provide a preparation method and application of a carbon-based adsorbent with a silica-alumina molecular sieve as a skeleton. The adsorbent is successfully synthesized by alkali treatment and carbon deposition steps using a silica-alumina molecular sieve as a base material. The adsorbent is a carbon-silica-alumina molecular sieve composite adsorbent material with high N2 adsorption capacity and high CH4 / N2 selectivity, which can solve the problems of low CH4 purity and low yield in gas recovery and utilization, and has good industrial application prospect.

[0007] In order to achieve the above purposes, the technical solutions of the present application are as follows:

[0008] A preparation method of a carbon-based adsorbent with a silica-alumina molecular sieve as a skeleton, comprising the following steps:

[0009] (1) placing the silicon-aluminum molecular sieve into an alkali solution with a certain concentration for impregnation treatment, then washing, filtering and drying;

[0010] (2) placing the product in step (1) into a rotary tube furnace, heating to a certain temperature under an inert atmosphere, and introducing a proper amount of carbon source to crack and deposit carbon on the surface of the silicon-aluminum molecular sieve by gas phase deposition to obtain a carbon-based adsorbent with the silicon-aluminum molecular sieve as the skeleton.

[0011] As a preferred embodiment in the present application, the adsorbent is used in a process for separating CH4 / N2 by pressure swing adsorption, and has a good adsorption capacity for N2 and selectivity for CH4 / N2.

[0012] As a preferred embodiment in the present application, the silicon-aluminum molecular sieve used in step (1) is any one of natural clinoptilolite, ZSM-5, 13X and 5A.

[0013] As a preferred embodiment in the present application, the drying temperature in step (1) is 120°C, and the drying time is 12 h.

[0014] As a preferred embodiment in the present application, in step (1), the alkali used is any one of sodium hydroxide, potassium hydroxide and sodium metaaluminate; and the concentration of the alkali solution is 0.1-0.8 mol / L (specifically, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L, 0.8 mol / L, etc.).

[0015] As a preferred embodiment in the present application, the impregnation treatment time in step (1) is 2-8 h (specifically, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, etc.).

[0016] As a preferred embodiment in the present application, the inert atmosphere in step (2) is N2 atmosphere, argon atmosphere or a mixed atmosphere of N2 and argon.

[0017] As a preferred embodiment in the present application, the temperature rising in step (2) is performed at a temperature rising rate of 10°C / min.

[0018] As a preferred embodiment in the present application, in step (2), the carbon source is any one of benzene, methane and cyclohexane.

[0019] As a preferred embodiment of the present application, in step (2), the temperature for vapor deposition is 600-900℃ (specifically, 600℃, 650℃, 700℃, 750℃, 800℃, 850℃, 900℃, etc.); the time for vapor deposition is 30-200min (specifically, 30min, 40min, 50min, 60min, 70min, 80min, 90min, 100min, 110min, 120min, 130min, 140min, 150min, 160min, 170min, 180min, 190min, 200min, etc.).

[0020] In step (2), the temperature for vapor deposition is more preferably 650-850℃; the time for vapor deposition is 70-150min.

[0021] The carbon-silicon aluminum molecular sieve composite adsorption material prepared by the above preparation method or any step is protected in the present application.

[0022] The composite adsorption material is a porous material with narrow pore opening and large pore volume, and the silicon aluminum molecular sieve treated with alkali has increased defect sites on the pore opening surface and improved openness of internal active sites. When carbon-containing organic matter is introduced into the silicon aluminum molecular sieve by vapor deposition, the organic matter is cracked and carbonized at the internal active sites and the defect sites of the pore opening, and the carbon layer on the inner and outer surfaces is gradually formed by adjusting the deposition reaction degree, so as to passivate the acid centers on the surface of the molecular sieve and adjust the pore size of the molecular sieve. The chemical properties and pore channel of the carbon material and the silicon aluminum molecular sieve are combined, so that the high-performance composite adsorbent material with different micro-pore sizes can be simply and easily prepared.

[0023] The carbon-silicon aluminum molecular sieve composite adsorption material is also protected in the present application, which is applied to the CH4 / N2 separation process; in the CH4 / N2 separation application, the adsorption amount of N2 and the CH4 / N2 selectivity are high.

[0024] Compared with the prior art, the present application has the following beneficial effects:

[0025] (1) The carbon-silicon aluminum molecular sieve composite adsorption material prepared by the present application has a significant desilication effect and a slight dealumination effect by alkali treatment, which can increase the defect sites and active sites on the inner and outer surfaces of the molecular sieve, and is beneficial to the uniform performance of the subsequent carbon deposition reaction.

[0026] (ii) The carbon-silicon aluminum molecular sieve composite adsorbent material prepared by the present application can passivate the acid center on the surface of the molecular sieve, adjust the polar site on the surface of the molecular sieve, and adjust the pore size of the molecular sieve, so that the adsorbent material has obviously improved adsorption selectivity and adsorption capacity for N2, and further improves the CH4 purification and separation effect of the adsorbent material on CH4 / N2 mixed gas.

[0027] (iii) The preparation process of the carbon-silicon aluminum molecular sieve composite adsorbent prepared by the present application is based on the actual production of the adsorbent product in the current industrial production, and is a process technology that can be quickly applied in industrial production. DETAILED DESCRIPTION

[0028] The present application will be further described in detail through specific examples, so that the technical solutions and purposes of the present application can be better understood. The specific examples described herein are only used to explain the present application, and do not limit the content involved in the present application.

[0029] The static adsorption data (CH4 adsorption capacity and CH4 / N2 separation coefficient) involved in the embodiments of the present application are obtained by using a manual adsorption instrument EA-III to preliminarily evaluate and screen the CH4 / N2 mixed gas separation performance of the adsorbent. Under the condition of normal pressure and a certain temperature, the adsorption volume of the adsorbent on single components He, CH4 and N2 within 3 min is tested, so as to calculate the adsorption capacity of the adsorbent on CH4 and N2 respectively, and obtain the corresponding dynamic separation coefficient of the CH4 / N2 mixed gas, which are respectively shown in formula (1) and formula (2).

[0030]

[0031]

[0032] In the formula, q i and q j are the adsorption capacities of gas components i and j, mL / g; V i is the adsorption volume of gas component i, mL; V He is the adsorption volume of He, mL; K value corresponds to the equilibrium coefficient at the test temperature; m is the mass of the test sample, g; S ads is the separation coefficient of the mixed gas; p i and p j are the adsorption pressures, MPa.

[0033] The product gas CH4 purity and yield data involved in the embodiments of the present application are determined by single-tower pressure swing adsorption experiment. The specific method is as follows: CH4 gas (100%) is charged, the charging time is 5 s, the charging pressure is 0.3 MPa, the adsorption time is controlled for 60 s, the desorption is stopped, the desorption is performed to 0.2 MPa for 15 s, then the reverse desorption is performed to normal pressure for 30 s, the vacuum pump reaches a vacuum degree of -0.08 MPa for 90 s, and the adsorbent is regenerated. After the single-tower adsorption process reaches a steady state, the corresponding purified gas, desorption gas, reverse desorption gas and evacuation desorption gas are collected and measured. The collected gas is analyzed for component content by gas chromatography.

[0034] In the single-tower pressure swing adsorption desorption experiment, the raw material gas is composed of 75% CH4 and 25% N2, and the product gas is composed of purified gas and desorption gas. The CH4 concentration and recovery rate of the product gas are shown in formula (3) and formula (4).

[0035]

[0036]

[0037] In the formula, C is the CH4 concentration of the product gas, %; η is the CH4 recovery rate of the product gas, %; C0 is the CH4 concentration of the raw material gas, %; V0 is the raw material gas volume when charging, mL; C1 is the CH4 concentration of the purified gas, %; V1 is the purified gas volume, mL; C2 is the CH4 concentration of the desorption gas, %; V2 is the desorption gas volume, mL; V3 is the reverse desorption gas volume, mL; V4 is the evacuation desorption gas volume, mL; C5 is the CH4 concentration of the charging gas, %; and V5 is the CH4 volume of the charging gas, mL.

[0038] Example 1:

[0039] A preparation method of a carbon-based adsorbent with a silicon-aluminum molecular sieve as a skeleton, and the specific preparation process is as follows:

[0040] (1) 50 g of clinoptilolite molecular sieve is added to 1 L of 0.2 mol / L sodium hydroxide solution for immersion for 8 h, then washed, suction filtered, and dried in an oven at 120℃ for 12 h.

[0041] (2) The clinoptilolite molecular sieve treated with alkali in step (1) is placed in a rotary tube furnace, a N2 gas flow of 250 mL / min is continuously introduced, the temperature is raised to 700℃ at a heating rate of 10℃ / min, then an appropriate amount of benzene vapor is continuously introduced with a N2 gas flow of 100 mL / min, the introduction of benzene vapor is stopped after 40 min, heating is stopped, and the temperature is naturally reduced to room temperature, then the carbon-silicon-aluminum molecular sieve composite adsorbent is taken out, and numbered as Example 1.

[0042] The static adsorption device was used to test the adsorption capacity of N2 and the separation coefficient of CH4 / N2 mixed gas, and the results are shown in Table 1.

[0043] The single-tower pressure swing adsorption device was used to test the adsorption separation effect of 75% CH4-25% N2 mixed gas, and the results are shown in Table 2.

[0044] Example 2

[0045] A preparation method of a carbon-based adsorbent with a silicon-aluminum molecular sieve as a skeleton, and the specific preparation process is as follows:

[0046] (1) 50g of ZSM-5 molecular sieve was added to 1L of 0.4mol / L sodium hydroxide solution for 5h, then washed, suction filtered, and dried in an oven at 120℃ for 12h.

[0047] (2) The alkali-treated ZSM-5 molecular sieve was placed in a rotary tube furnace, and a N2 gas stream of 250mL / min was continuously introduced, and the temperature was raised to 650℃ at a heating rate of 10℃ / min, then a proper amount of benzene vapor was continuously introduced with a N2 gas stream of 100mL / min, after 150min, the benzene vapor was stopped and the heating was stopped, and after the temperature naturally dropped to room temperature, the carbon-silicon-aluminum molecular sieve composite adsorbent was taken out, numbered as Example 2.

[0048] The static adsorption device was used to test the adsorption capacity of N2 and the separation coefficient of CH4 / N2 mixed gas, and the results are shown in Table 1.

[0049] The single-tower pressure swing adsorption device was used to test the adsorption separation effect of 75% CH4-25% N2 mixed gas, and the results are shown in Table 2.

[0050] Example 3

[0051] A preparation method of a carbon-based adsorbent with a silicon-aluminum molecular sieve as a skeleton, and the specific preparation process is as follows:

[0052] (1) 50g of 13X molecular sieve was added to 1L of 0.8mol / L potassium hydroxide solution for 3h, then washed, suction filtered, and dried in an oven at 120℃ for 12h.

[0053] (2) The alkali-treated 13X molecular sieve was placed in a rotary tube furnace, and an argon gas stream of 250mL / min was continuously introduced, and the temperature was raised to 850℃ at a heating rate of 10℃ / min, then an argon gas stream of 100mL / min and a CH4 gas stream of 100mL / min were continuously introduced at the same time, after 100min, the CH4 was stopped and the heating was stopped, and after the temperature naturally dropped to room temperature, the carbon-silicon-aluminum molecular sieve composite adsorbent was taken out, numbered as Example 3.

[0054] The adsorption capacity for N2 and the separation coefficient for CH4 / N2 mixed gas were tested by using a static adsorption device, and the results are shown in Table 1.

[0055] The adsorption separation effect for a 75% CH4-25% N2 mixed gas by volume was tested by using a single-tower pressure swing adsorption device, and the results are shown in Table 2.

[0056] Example 4

[0057] A preparation method of a carbon-based adsorbent with a silicon-aluminum molecular sieve as a skeleton, and the specific preparation process is as follows:

[0058] (1) 50g of 5A molecular sieve was immersed in 1L of 0.1mol / L sodium hydroxide solution for 8h, then washed, suction filtered, and dried in an oven at 120℃ for 12h.

[0059] (2) The 5A molecular sieve treated with alkali was placed in a rotary tube furnace, and a mixed gas stream of 250mL / min of nitrogen and argon was continuously introduced, and the temperature was raised to 750℃ at a heating rate of 10℃ / min, then a mixed gas stream of 100mL / min of nitrogen and argon and a cyclohexane gas stream of 100mL / min were continuously introduced, and after 70min, the introduction of cyclohexane was stopped, heating was stopped, and after the temperature naturally decreased to room temperature, the carbon-silicon-aluminum molecular sieve composite adsorbent was taken out, and was numbered as Example 4.

[0060] The adsorption capacity for N2 and the separation coefficient for CH4 / N2 mixed gas were tested by using a static adsorption device, and the results are shown in Table 1.

[0061] The adsorption separation effect for a 75% CH4-25% N2 mixed gas by volume was tested by using a single-tower pressure swing adsorption device, and the results are shown in Table 2.

[0062] Comparative Example 1

[0063] A preparation method and application of a traditional ion exchange type silicon-aluminum molecular sieve adsorbent for separating CH4 / N2 by using a pressure swing adsorption method, and the specific preparation process is as follows:

[0064] 50g of ZSM-5 molecular sieve was added to 1L of 0.8mol / L calcium chloride solution, and the calcium chloride solution was exchanged at a temperature of 60℃ for 8h, and the exchange was performed twice, and after each exchange, the sample was washed with deionized water and dried in an oven at 120℃ for 12h, to obtain a traditional ion exchange type silicon-aluminum molecular sieve sample, and was numbered as Comparative Example 1.

[0065] The adsorption capacity for N2 and the separation coefficient for CH4 / N2 mixed gas were tested by using a static adsorption device, and the results are shown in Table 1.

[0066] The single-tower pressure swing adsorption device was used to test the adsorption separation effect of the adsorbent on the 75% CH4-25% N2 mixed gas, and the results are shown in Table 2.

[0067] Comparative Example 2

[0068] A preparation method and application of a traditional carbon molecular sieve adsorbent for separating CH4 / N2 by pressure swing adsorption are provided, and the specific preparation process is as follows:

[0069] 50g of phenolic resin carbon precursor was placed in a rotary tube furnace, and 250mL / min of N2 gas flow was continuously introduced, and the temperature was raised to 650℃ at a heating rate of 10℃ / min, then 100mL / min of N2 gas flow was used to continuously introduce appropriate amount of benzene vapor, 40min later, stop introducing benzene vapor and stop heating, after the temperature naturally dropped to room temperature, the carbon molecular sieve adsorbent was taken out, numbered as Comparative Example 2.

[0070] The static adsorption device was used to test the adsorption capacity of N2 and the separation coefficient of CH4 / N2 mixed gas, and the results are shown in Table 1.

[0071] The single-tower pressure swing adsorption device was used to test the adsorption separation effect of the adsorbent on the 75% CH4-25% N2 mixed gas, and the results are shown in Table 2.

[0072] Comparative Example 3

[0073] A preparation method and application of a carbon-silicon aluminum molecular sieve composite adsorbent for separating CH4 / N2 by pressure swing adsorption are provided, and the specific preparation process is as follows:

[0074] ZSM-5 molecular sieve was placed in a rotary tube furnace, and 250mL / min of N2 gas flow was continuously introduced, and the temperature was raised to 650℃ at a heating rate of 10℃ / min, then 100mL / min of N2 gas flow was used to continuously introduce appropriate amount of benzene vapor, 150min later, stop introducing benzene vapor and stop heating, after the temperature naturally dropped to room temperature, the carbon-silicon aluminum molecular sieve composite adsorbent was taken out, numbered as Comparative Example 3. The static adsorption device was used to test the adsorption capacity of N2 and the separation coefficient of CH4 / N2, and the results are shown in Table 1.

[0075] The single-tower pressure swing adsorption device was used to test the adsorption separation effect of the adsorbent on the 75% CH4-25% N2 mixed gas, and the results are shown in Table 2.

[0076] Table 1 Static adsorption test results of adsorbents in examples and comparative examples on CH4 and N2 (3min)

[0077]

[0078]

[0079] Table 2 Results of single column pressure swing adsorption of adsorbents in examples and comparative examples on 75% CH4-25% N2mixed gas

[0080]

[0081] As can be seen from Table 1 and Table 2, the static adsorption data (N2adsorption capacity and CH4 / N2separation coefficient) and single column pressure swing adsorption data (CH4purity and yield of product gas) of the ion exchange type silicon-aluminum molecular sieve and carbon molecular sieve adsorbents prepared by the traditional method in the comparative examples are low, while the separation and adsorption performance of the adsorbents prepared by the composite method of carbon material and silicon-aluminum molecular sieve in the examples is effectively improved (the CH4purity of product gas can reach 95%, and the CH4yield of product gas can reach 85%). Compared with Example 2 and Comparative Example 3, the CH4 / N2separation effect obtained by the modification method of alkali treatment and re-deposition of the molecular sieve adsorbent is obviously better than that of the sample directly deposited, and the alkali treatment process not only exposes more active sites to facilitate the uniform deposition of the subsequent deposition, but also expands the pore size to some extent, providing more space for the deposition process.

[0082] The silicon-aluminum molecular sieve is a porous material with large specific surface area, regular pore structure, polar surface and acid center. In CH4 / N2separation, since the polarization rate of CH4is higher than that of N2, the silicon-aluminum molecular sieve will adsorb a large amount of CH4, but N2has a faster diffusion speed than CH4, resulting in low selectivity of the molecular sieve in separating CH4 / N2. Therefore, by depositing carbon on the surface of the molecular sieve through gas phase deposition of an organic carbon source, the acid center of the molecular sieve is used to adjust the pore size of the molecular sieve, and the characteristics of the carbon material and the silicon-aluminum molecular sieve are appropriately combined to design a high-performance composite adsorbent material with narrow pore opening and large pore volume, which is simple and easy to control, thereby improving the adsorption capacity of the adsorbent for N2and the selectivity of the adsorbent for CH4 / N2. Especially, the use of an alkali solution for pretreatment of the molecular sieve can increase the openness of the defect sites on the surface of the molecular sieve and the internal active center sites, thereby improving the adjustment of the chemical properties and pore structure of the molecular sieve by the cracked carbon in the carbon deposition.

[0083] The aforementioned basic examples and each further selected example can be freely combined to form a plurality of embodiments, all of which are embodiments that can be used and claimed by the present application. In the present application, each selected example can be combined with any basic example and selected example. Those skilled in the art can know that there are numerous combinations.

[0084] The above merely describes preferred embodiments of the present application, and is not used to limit the present application, any modification, equivalent replacement and improvement within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. Use of a carbon-based adsorbent having a silicoaluminous molecular sieve backbone for separating CH4 / N2 by pressure swing adsorption, characterized in that, The method comprises the following steps: (1) immersing the silico-alumina molecular sieve in an alkali solution with a certain concentration, then washing, filtering and drying; (2) placing the product in step (1) in a rotary tube furnace, heating to a certain temperature under an inert atmosphere, and introducing a proper amount of carbon source to deposit carbon on the surface of the silico-alumina molecular sieve by gas phase deposition, thereby obtaining a carbon-based adsorbent with the silico-alumina molecular sieve as a skeleton; In step (1), the silico-alumina molecular sieve used is ZSM-5; the alkali used is any one of sodium hydroxide, potassium hydroxide and sodium metaaluminate; the concentration of the alkali solution is 0.1-0.8 mol / L; In step (2), the carbon source is any one of benzene, methane and cyclohexane; the temperature for gas phase deposition is 600-900 ℃; and the time for gas phase deposition is 30-200 min.

2. Use according to claim 1, characterized in that: The drying temperature in step (1) is 120 ℃, and the drying time is 12 h.

3. Use according to claim 1, characterized in that: The time for immersing treatment in step (1) is 2-8 h.

4. Use according to claim 1, characterized in that: The inert atmosphere in step (2) is N2 atmosphere, argon atmosphere or a mixed atmosphere of N2 and argon.

5. Use according to claim 1, characterized in that, The temperature in step (2) is raised at a rate of 10 ℃ / min.

6. Use according to claim 1, characterized in that: In step (2), the temperature for gas phase deposition is 650-850 ℃; and the time for gas phase deposition is 70-150 min.

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