Porous carbon material with high ethane adsorption selectivity and preparation method thereof

Abstract

This invention belongs to the field of adsorption materials and discloses a porous carbon material with high ethane adsorption selectivity and its preparation method. The preparation method includes the following steps: (1) adding commercial activated carbon to a mixed solution of sodium hydroxide and sodium carbonate and ultrasonically treating it; (2) transferring the above mixture to a silicon carbide crucible and drying it in a forced-air drying oven; (3) placing the silicon carbide crucible containing the dried sample into a microwave catalytic instrument and performing a microwave activation reaction in a nitrogen atmosphere; (4) after the reaction is completed, allowing the sample to cool naturally to room temperature, removing the sample, washing it until the washing solution is neutral, and drying it to obtain a porous carbon material with high ethane adsorption selectivity. The porous carbon material prepared by this invention has excellent ethane adsorption selectivity, excellent ethane adsorption capacity, and a well-developed porous structure, and has good industrial application value in the adsorption and separation of ethane / ethylene mixed gases.

Description

Technical Field

[0001] This invention relates to the field of adsorption materials, specifically to a porous carbon material with high ethane adsorption selectivity and its preparation method. Background Technology

[0002] Ethylene is the world's most consumed chemical, and its derivatives account for more than 70% of global petrochemical products, earning it the title of "mother of the petrochemical industry." Ethylene is primarily produced through ethane cracking. However, due to the extreme similarity in physical properties between ethylene and ethane, high-pressure cryogenic distillation is currently the main industrial method for separation. This process accounts for 75-85% of the total ethylene production cost and suffers from high energy consumption and high carbon emissions. Therefore, developing energy-saving and carbon-reducing ethylene / ethane separation and purification processes has significant industrial value.

[0003] To overcome these limitations, academia and industry have shifted their core objective from "energy-consuming separation" to "selective separation." Adsorption separation technology utilizes the difference in selective adsorption of ethylene and ethane by porous materials, enabling the separation of mixed gases at room temperature. It offers advantages such as mild operating conditions and low energy consumption, and its core lies in the development of high-performance selective adsorbents.

[0004] Materials used for ethylene / ethane adsorption separation can be divided into two categories: ethylene-selective adsorption materials and ethane-selective adsorption materials. The development of ethylene-selective adsorption materials mainly follows two approaches: one is to introduce unsaturated metal sites (such as Cu) into the material framework or pores. + Ag + There are two main approaches to ethylene / ethane separation: one is to preferentially adsorb ethylene by forming stronger π-complexes with ethylene molecules; the other is to utilize the adjustable pore size of porous materials to prepare materials with pore sizes between the dynamic diameters of ethylene and ethane molecules, achieving separation through sieving. While these materials exhibit high selectivity for ethylene / ethane separation, their application in industrial cracked gas separation still presents several challenges: industrial cracked gas contains up to 90% ethylene, requiring large amounts of adsorbent and larger adsorption beds; the target product, ethylene, must be obtained through desorption, resulting in a complex and energy-intensive separation process; materials based on π-complexes have high energy consumption for desorption and regeneration; and materials based on sieving suffer from slow ethylene diffusion rates, elongated mass transfer zones, and low adsorbent utilization, necessitating longer adsorption beds, slower inlet gas flow rates, or longer circulation times, significantly reducing the processing capacity per unit volume of adsorbent and increasing equipment size and energy consumption.

[0005] In contrast, when using ethane selective adsorption materials to separate ethylene / ethane from cracked gas, only a low concentration of ethane (typically about 5%-10% by volume) needs to be removed through a single adsorption process to directly obtain high-purity ethylene. This greatly simplifies the separation process, reduces energy consumption, and significantly improves the economics of the entire separation and purification process. Therefore, ethane selective adsorption is an ideal technical approach to solving the energy consumption problem in ethylene / ethane separation, and a breakthrough in this technology will have a profound impact on the petrochemical industry.

[0006] Developing high-performance ethane-selective adsorption materials is one of the core research directions in academia and industry. Carbon materials, with their excellent structural stability, unique tunable pore structure, and cost advantages, are currently the most practically applicable and cost-effective adsorption materials, and ideal candidates for ethylene / ethane adsorption and separation. In recent years, scholars both domestically and internationally have conducted extensive research on ethane-selective carbon-based adsorption materials: Professor Lu Anhui's research group at Dalian University of Technology prepared highly graphitized porous carbon GC-800, which achieved an ethane adsorption capacity of 2.16 mmol / g and an ethane / ethylene selectivity of 2.40 at room temperature and pressure; Professor João Pires' research group at the University of Lisbon, Portugal, prepared a series of porous carbon materials using crude glycerol, a byproduct of biodiesel, as raw material, with G@800 / 1 achieving a BET specific surface area of ​​1720 m². 2 The ethane / ethylene selectivity is 2.40 for g, and approximately 1.75 for Gdop0.75. These studies indicate that porous carbon materials possess well-developed pore structures and good ethane adsorption capacity. However, the core bottleneck currently restricting their industrial application is the still relatively low ethane / ethylene adsorption selectivity (generally below 3.0), which is significantly lower than the minimum selectivity of 4.0 required for practical applications. Summary of the Invention

[0007] To address the shortcomings and deficiencies of existing adsorption materials and preparation techniques, the present invention aims to provide a porous carbon material with high ethane adsorption selectivity and its preparation method. Compared with currently reported ethane / ethylene adsorption and separation materials, the present invention provides a porous carbon material and its preparation method that possess excellent ethane adsorption selectivity, superior ethane adsorption capacity, and a well-developed porous structure.

[0008] The objective of this invention is achieved through the following technical solution: In a first aspect, the present invention provides a method for preparing a porous carbon material with high ethane adsorption selectivity, comprising the following steps: (1) Take 1.0g of commercial activated carbon and add it to a 20mL mixed solution of sodium hydroxide and sodium carbonate, and sonicate for 10min.

[0009] (2) Transfer the mixture to a silicon carbide crucible, and then place the silicon carbide crucible containing commercial coconut shell activated carbon and a mixed solution of sodium hydroxide and sodium carbonate in a forced-air drying oven and dry at 80°C for 6 hours.

[0010] (3) Place the silicon carbide crucible containing the dried sample into the microwave catalytic instrument, purge the instrument cavity with nitrogen gas (flow rate of 100 mL / min) for 20 min, and then start the microwave catalytic instrument to carry out the activation reaction in the nitrogen atmosphere.

[0011] (4) After the reaction is complete, the sample is cooled to room temperature, then removed and washed with 1.0 mol / L hydrochloric acid and water sequentially until the washing solution is neutral. Then the sample is placed in a forced-air drying oven and dried at 80°C for 6 hours to obtain the porous carbon material disclosed in this invention.

[0012] Preferably, in step (1), the preparation ratio of the mixed solution of sodium hydroxide and sodium carbonate is 1.0:(0.5-2.0):(1.0-3.0) of the mass ratio of commercial activated carbon to sodium hydroxide and sodium carbonate.

[0013] Preferably, in step (3), the output power of the microwave catalytic converter is 500-800W.

[0014] Preferably, the microwave irradiation time in step (3) is 5-20 min.

[0015] Secondly, the present invention provides a porous carbon material with high ethane adsorption selectivity, which is prepared by the above method.

[0016] Thirdly, the present invention provides a porous carbon material with high ethane adsorption selectivity for adsorption and separation of ethane / ethylene mixed gas.

[0017] Preferably, the porous carbon material preferentially adsorbs ethane. Under conditions of 25°C and 1.0 bar, the porous carbon material exhibits an adsorption selectivity of up to 4.47 for an equimolar mixture of ethane and ethylene, and an adsorption capacity of 4.94 mmol / g for ethane.

[0018] The beneficial effects of this invention are as follows: 1. The porous carbon material prepared by this invention has excellent ethane adsorption selectivity, excellent ethane adsorption capacity and well-developed porous structure, and has great industrial application value in adsorbing and separating ethane / ethylene mixed gases.

[0019] 2. The raw materials used in this invention are inexpensive commercial activated carbon and sodium hydroxide / sodium carbonate solution with low concentration, making the raw materials economical. The carbonization and activation process is carried out in a microwave catalytic instrument with low output power and short preparation time. The entire preparation process is simple, easy to implement, and highly repeatable.

[0020] 3. This invention uses commercial activated carbon as the carbon source and employs microwave-assisted activation technology. By adjusting and optimizing the preparation parameters, the prepared porous carbon material achieves a high ethane adsorption selectivity of 4.47 and an ethane adsorption capacity of 4.94 mmol / g. Attached Figure Description

[0021] The present invention will be further described with reference to the accompanying drawings, but the embodiments in the drawings do not constitute any limitation on the present invention. For those skilled in the art, other drawings can be obtained based on the following drawings without creative effort.

[0022] Figure 1 The nitrogen adsorption-desorption isotherms at -196°C for the porous carbon materials prepared in Examples 1-6 and the material prepared in Comparative Example 1.

[0023] Figure 2 The adsorption isotherms of ethane at 25°C for the porous carbon materials prepared in Examples 1-6 and the material prepared in Comparative Example 1.

[0024] Figure 3 The adsorption isotherms of ethylene at 25°C for the porous carbon materials prepared in Examples 1-6 and the material prepared in Comparative Example 1.

[0025] Figure 4 The IAST adsorption selectivity of the porous carbon materials prepared in Examples 1-6 for equimolar ethane / ethylene mixed gas at 25°C.

[0026] Figure 5 The porous carbon materials prepared in Examples 4-6 are compared with those in Control Example 2 (in the figure, blue represents metal-organic framework material and purple represents porous carbon material) under the conditions of 25°C and 1.0 bar for the adsorption selectivity of equimolar ethane / ethylene mixed gas. Detailed Implementation

[0027] The technical solution of the present invention is illustrated below through specific examples. It should be understood that the one or more method steps mentioned in the present invention do not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps; it should also be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Furthermore, unless otherwise stated, the numbering of each method step is merely a convenient tool for identifying each method step, and not for limiting the order of the method steps or defining the scope of the present invention. Changes or adjustments to their relative relationships, without substantially altering the technical content, should also be considered within the scope of the present invention.

[0028] For the adsorption separation of ethylene / ethane, adsorbent materials can be divided into two types: ethylene-selective adsorbent materials and ethane-selective adsorbent materials. Regarding the development of ethylene-selective adsorbent materials, researchers have mainly adopted two approaches: one is to introduce unsaturated metal sites (such as Cu) into the material's framework / pores. + Ag + (etc.), so that the adsorbent material forms a stronger π-complex with ethylene gas molecules (Ling Zhang, Libo Li, Enlai Hu, et al. Boosting ethylene / ethane separation within copper(I)-chelated Metal-organic frameworks through tailor-made aperture and specific π-complexation [J]. AdvancedScience. 2020; 7: 1901918-1901924); secondly, by utilizing the adjustable pore size of porous materials, porous materials with pore sizes slightly larger than the dynamic diameter of ethylene molecules and slightly smaller than the dynamic diameter of ethane molecules are developed, and the separation of ethylene / ethane is achieved through the sieving principle (Haoyuan Luo, Daohao Zhou, Fei Teng, et al. Precisecontrolling pore size distribution at sub-angstrom scale in granular novelcarbon molecular sieves derived from coconut shell for separating ethyleneand ethane [J]. SCIENCE CHINA Materials. 2025; 68(7): 2449-2458).

[0029] Professor Lu Anhui's research group at Dalian University of Technology prepared highly graphitized porous carbon GC-800 for the adsorption and separation of ethylene / ethane mixed gases. This material exhibits an adsorption capacity of 2.16 mmol / g for ethane at room temperature and pressure, and a selectivity of 2.40 for ethane / ethylene (Liu Ru-shuai, Tang Fan, Shi Xiao-dong, et al. Preparation of highly graphitized porous carbon and its ethane / ethylene separation performance [J]. New Carbon Materials. 2024; 39(5): 1027-1036). Professor João Pires' research group at the University of Lisbon, Portugal, prepared a series of porous carbon materials using crude glycerol, a byproduct of biodiesel, as raw material. Among them, the BET specific surface area of ​​the G@800 / 1 material reached 1720 m². 2 / g, the selectivity for ethane / ethylene at room temperature and pressure is 2.40 (Mary Batista, Moisés L. Pinto, Renato Carvalho, et al. Glycerin-based adsorbents for the separation of ethane and ethylene [J]. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 2022; 634:127975-127984); the selectivity for ethane / ethylene of Gdop0.75 material is approximately 1.75 (Mary Batista, RenatoCarvalho, Moisés L. Pinto et al. Novel carbonaceous adsorbents prepared from glycerin waste and dopamine for gas separation [J]. Molecules. 2023; 28:4071-4084).

[0030] To better understand the above technical solutions, exemplary embodiments of the present invention are described in more detail below. While exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the invention to those skilled in the art.

[0031] The present invention will be further described below with reference to the following embodiments.

[0032] Example 1 (1) Weigh 0.5g of sodium hydroxide and 1.0g of sodium carbonate and dissolve them in 20mL of water. Weigh 1.0g of commercial activated carbon and add it to the 20mL mixed solution of sodium hydroxide and sodium carbonate prepared above (the mass ratio of commercial activated carbon / sodium hydroxide and sodium carbonate is 1.0 / 0.5 / 1.0). Sonicate for 10min.

[0033] (2) Transfer the mixture to a silicon carbide crucible, and then place the silicon carbide crucible containing commercial coconut shell activated carbon and a mixed solution of sodium hydroxide and sodium carbonate in a forced-air drying oven and dry at 80°C for 6 hours.

[0034] (3) Place the silicon carbide crucible containing the dried sample into the microwave catalytic instrument, purge the instrument cavity with nitrogen gas at 100 mL / min for 20 min, then start the microwave catalytic instrument with an output power of 500 W and a microwave irradiation time of 5 min.

[0035] (4) After the reaction is complete, the sample is cooled to room temperature, taken out, and washed with 1.0 mol / L hydrochloric acid and water sequentially until the washing solution is neutral. Then the sample is placed in a forced-air drying oven and dried at 80°C for 6 hours to obtain the porous carbon material disclosed in this invention, denoted as material 1#.

[0036] Example 2 (1) Weigh 0.5g of sodium hydroxide and 3.0g of sodium carbonate and dissolve them in 20mL of water. Weigh 1.0g of commercial activated carbon and add it to the 20mL mixed solution of sodium hydroxide and sodium carbonate prepared above (the mass ratio of commercial activated carbon / sodium hydroxide and sodium carbonate is 1.0 / 0.5 / 3.0). Sonicate for 10min.

[0037] (2) Same as Example 1.

[0038] (3) Place the silicon carbide crucible containing the dried sample into the microwave catalytic instrument, purge the instrument cavity with nitrogen gas at 100 mL / min for 20 min, then start the microwave catalytic instrument with an output power of 500 W and a microwave irradiation time of 20 min.

[0039] (4) Same as in Example 1, the porous carbon material prepared is referred to as Material 2#.

[0040] Example 3 (1) Weigh 1.0g of sodium hydroxide and 2.0g of sodium carbonate and dissolve them in 20mL of water. Weigh 1.0g of commercial activated carbon and add it to the 20mL mixed solution of sodium hydroxide and sodium carbonate prepared above (the mass ratio of commercial activated carbon / sodium hydroxide and sodium carbonate is 1.0 / 1.0 / 2.0). Sonicate for 10min.

[0041] (2) Same as Example 1.

[0042] (3) Place the silicon carbide crucible containing the dried sample into the microwave catalytic instrument, purge the instrument cavity with nitrogen gas at 100 mL / min for 20 min, then start the microwave catalytic instrument with an output power of 600 W and a microwave irradiation time of 10 min.

[0043] (4) Same as in Example 1, the porous carbon material prepared is referred to as Material 3#.

[0044] Example 4 (1) Weigh 1.0g of sodium hydroxide and 3.0g of sodium carbonate and dissolve them in 20mL of water. Weigh 1.0g of commercial activated carbon and add it to the 20mL mixed solution of sodium hydroxide and sodium carbonate prepared above (the mass ratio of commercial activated carbon / sodium hydroxide and sodium carbonate is 1.0 / 1.0 / 3.0). Sonicate for 10min.

[0045] (2) Same as Example 1.

[0046] (3) Place the silicon carbide crucible containing the dried sample into the microwave catalytic instrument, purge the instrument cavity with nitrogen gas at 100 mL / min for 20 min, then start the microwave catalytic instrument with an output power of 700 W and a microwave irradiation time of 20 min.

[0047] (4) Same as in Example 1, the porous carbon material prepared is referred to as material 4#.

[0048] Example 5 (1) Weigh 2.0g of sodium hydroxide and 2.0g of sodium carbonate and dissolve them in 20mL of water. Weigh 1.0g of commercial activated carbon and add it to the 20mL mixed solution of sodium hydroxide and sodium carbonate prepared above (the mass ratio of commercial activated carbon / sodium hydroxide and sodium carbonate is 1.0 / 2.0 / 2.0). Sonicate for 10min.

[0049] (2) Same as Example 1.

[0050] (3) Place the silicon carbide crucible containing the dried sample into the microwave catalytic instrument, purge the instrument cavity with nitrogen gas at 100 mL / min for 20 min, then start the microwave catalytic instrument with an output power of 800 W and a microwave irradiation time of 10 min.

[0051] (4) Same as in Example 1, the porous carbon material prepared is referred to as material 5#.

[0052] Example 6 (1) Weigh 2.0g of sodium hydroxide and 3.0g of sodium carbonate and dissolve them in 20mL of water. Weigh 1.0g of commercial activated carbon and add it to the 20mL mixed solution of sodium hydroxide and sodium carbonate prepared above (the mass ratio of commercial activated carbon / sodium hydroxide and sodium carbonate is 1.0 / 2.0 / 3.0). Sonicate for 10min.

[0053] (2) Same as Example 1.

[0054] (3) Place the silicon carbide crucible containing the dried sample into the microwave catalytic instrument, purge the instrument cavity with nitrogen gas at 100 mL / min for 20 min, then start the microwave catalytic instrument with an output power of 800 W and a microwave irradiation time of 20 min.

[0055] (4) Same as in Example 1, the porous carbon material prepared is referred to as material 6#.

[0056] Example 7 (1) Weigh 0.5g of sodium hydroxide and 1.0g of sodium carbonate and dissolve them in 20mL of water. Weigh 1.0g of commercial activated carbon and add it to the 20mL mixed solution of sodium hydroxide and sodium carbonate prepared above (the mass ratio of commercial activated carbon / sodium hydroxide / sodium carbonate is 1.0 / 0.5 / 1.0). Sonicate for 10min.

[0057] (2) Same as Example 1.

[0058] (3) Place the silicon carbide crucible containing the dried sample into the microwave catalytic instrument, purge the instrument cavity with nitrogen gas at 100 mL / min for 20 min, then start the microwave catalytic instrument with an output power of 500 W and a microwave irradiation time of 10 min.

[0059] (4) Same as in Example 1, the porous carbon material prepared is referred to as material 7#.

[0060] Example 8 (1) Weigh 2.0g of sodium hydroxide and 3.0g of sodium carbonate and dissolve them in 20mL of water. Weigh 1.0g of commercial activated carbon and add it to the 20mL mixed solution of sodium hydroxide and sodium carbonate prepared above (the mass ratio of commercial activated carbon / sodium hydroxide / sodium carbonate is 1.0 / 2.0 / 3.0). Sonicate for 10min.

[0061] (2) Same as Example 1.

[0062] (3) Place the silicon carbide crucible containing the dried sample into the microwave catalytic instrument, purge the instrument cavity with nitrogen gas at 100 mL / min for 20 min, then start the microwave catalytic instrument with an output power of 800 W and a microwave irradiation time of 10 min.

[0063] (4) Same as in Example 1, the porous carbon material prepared is referred to as Material 8#.

[0064] Compare with Example 1 Comparative Example 1 is commercial activated carbon without any treatment, denoted as Material 0#.

[0065] Compare with Example 2 Currently reported adsorption materials include metal-organic frameworks and porous carbon materials.

[0066] Metal-organic framework materials include: IITKGP-39: ①Debolina Mukherjee, Shyam Chand Pal, Jia-Xin Wang, etal. Two-in-one flexible metal-organic framework: one-step C2H4 purificationvia inverse C2H6-C2H4 and C2H2-CO2 separations [J]. Journal of the AmericanChemical Society. 2025; 147: 29255-29270. PCP-IPA-NH2: ② Haoran Sun, Fuqiang Chen, Rundao Chen, et al. Customizing metal-organic frameworks by Lego-brick strategy for one-steppurification of ethylene from a quaternary gas mixture [J]. Small. 2023; 19:2208182-2208189. ZU-925: ③ Peixin Zhang, Dengzhuo Zhou, Xian Suo, et al. Tailored synergistic binding environment in metal-organic frameworks for record one-step ethylene purification from multicomponent mixtures [J]. Angew. Chem. Int. Ed. 2025, 64, e18996. CAU-23: ④ Donghyun Kim, Bao Nguyen Truong a, Donghui Jo, et al. Single-step ethylene purification from ternary C2 hydrocarbon mixtures in a scalable metal-organic framework [J]. Chemical Engineering Journal. 2023;470: 143858-143864).

[0067] Porous carbon materials include: G@800 / 1: ① Mary Batista, Moisés L.Pinto, Renato Carvalho, et al. Glycerin-based adsorbents for the separation of ethane and ethylene [J]. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 2022; 634: 127975-127984. [[ID=⑨]]Gdop0.75: ② Mary Batista, Renato Carvalho, Moisés L. Pinto et al. Novel carbonaceous adsorbents prepared from glycerin waste and dopamine for gas separation [J]. Molecules. 2023; 28: 4071-4084.

[0068] Experimental examples It should be noted that there is a small error in the original text where "⑨" is used instead of "②" in the ID=9 content. This has been corrected in the translation.To illustrate the pore structure characteristics and adsorption / separation performance of the porous carbon materials 1#-6# prepared in each embodiment, we characterized the pore structure of the porous carbon materials 1#-6# and evaluated their adsorption / separation performance for ethane / ethylene.

[0069] Pore ​​structure characterization was performed using a Mack ASAP2460 surface area and pore size analyzer. The BET specific surface area and pore volume of the material were obtained by measuring the nitrogen adsorption-desorption curves at -196℃ (test range: relative pressure P / P0 < 0.995) and applying built-in analytical and calculation methods. The adsorption performance of ethane and ethylene was evaluated using a Mack 3Flex three-station multi-functional gas adsorption analyzer, where the adsorption isotherms for ethane and ethylene at 25℃ were measured. The adsorption selectivity of the material for an equimolar ethane / ethylene mixture was calculated based on the measured adsorption isotherm data using the ideal adsorption solution theory (IAST). This adsorption selectivity is termed the IAST adsorption selectivity. The results are as follows: Figure 1 The nitrogen adsorption-desorption isotherms at -196°C for porous carbon materials 1#-6# prepared for the examples and material 0# prepared for Control Example 1. Figure 1 The curves show that the adsorption isotherms of porous carbon materials 1#-6# are typical type I adsorption curves. In the low-pressure region, the N2 adsorption capacity increases sharply with increasing pressure, indicating that materials 1#-6# possess narrow micropores. Within these narrow micropores, the adsorbent-adsorbate interaction strengthens, leading to micropore filling at low pressures. This also demonstrates that materials 1#-6# have a rich microporous structure. On the other hand, from... Figure 1 It was observed that in the region of higher pressure, the adsorption-desorption curves of materials 1#-6# did not completely overlap, but instead showed a hysteresis loop. According to the classification of the International Union of Pure and Applied Chemistry (IUPAC), this hysteresis loop is an H4 type hysteresis loop, which indicates that mesoporous structures also exist in the materials.

[0070] Table 1 Material parameters of the examples and comparative examples

[0071] in: a 25℃ and 1.0 bar; b 25℃ and 1.0 bar, and an equimolar mixture of ethane and ethylene. Table 1 lists the BET specific surface area and pore volume parameters of porous carbon materials 1#-6# prepared in the examples and material 0# prepared in Control Example 1. From the data in the table, we can observe that compared with material 0#, the BET specific surface area and pore volume of materials 1#-6# are significantly increased. Combined with the preparation conditions of the examples, it was found that with the increase of the amount of activators sodium hydroxide and sodium carbonate, the increase of the output power of the microwave catalytic converter, and the extension of the microwave irradiation time, the specific surface area and pore volume of the prepared porous carbon materials are larger, with material 6# reaching a BET specific surface area of ​​828.7 m². 2 / g, pore volume reaches 0.49cm³. 3 / g.

[0072] Figure 2 and Figure 3 The adsorption isotherms of ethane and ethylene at 25°C are shown for the porous carbon materials 1#-6# prepared in the examples and material 0# prepared in Control Example 1, respectively. (Comparison) Figure 2 and Figure 3 It was found that, under the same temperature and pressure conditions, the porous carbon materials 1#-6# prepared in the examples all exhibited higher adsorption capacities for ethane than for ethylene. This indicates that the porous carbon materials disclosed in this invention preferentially adsorb ethane and possess a high ethane adsorption capacity. Porous carbon material 6# achieved an ethane adsorption capacity of 4.94 mmol / g at 25°C and 1.0 bar. Under the same conditions, the ethane adsorption capacities of porous carbon materials 1#-6#, ranked from largest to smallest, were: 6#>5#>4#>3#>2#>1#. This result is consistent with the order of their BET specific surface area and pore volume. This demonstrates that the well-developed microporous-mesoporous structure is a crucial structural basis for the adsorption and separation of ethane / ethylene by porous carbon materials.

[0073] Figure 4 The porous carbon materials 1#-6# prepared for the examples exhibit IAST adsorption selectivity for equimolar ethane / ethylene mixed gases at 25°C. Figure 4 It can be observed that the IAST adsorption selectivity of porous carbon materials 1#-6# for equimolar ethane / ethylene mixed gases gradually decreases with increasing mixed gas pressure. At 25℃ and 1.0 bar, the IAST adsorption selectivity of porous carbon materials 4# and 6# for equimolar ethane / ethylene mixed gases reaches 4.47 and 4.22, respectively, which is higher than that of currently reported adsorption materials (Control Example 2), including metal-organic framework materials and porous carbon materials, under the same conditions for equimolar ethane / ethylene mixed gases. Figure 5 As shown.

[0074] In summary, the porous carbon material disclosed in this invention has excellent ethane adsorption selectivity, excellent ethane adsorption capacity, and well-developed porous structure, and has great industrial application prospects in the adsorption and separation of ethane / ethylene gas.

[0075] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. The illustrative expressions of the above terms in this specification should not be construed as necessarily referring to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0076] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing a porous carbon material with high ethane adsorption selectivity, characterized in that, Includes the following steps: (1) Commercial activated carbon was added to a mixed solution of sodium hydroxide and sodium carbonate and ultrasonically treated; (2) Transfer the above mixture to a silicon carbide crucible and place it in a forced-air drying oven for drying; (3) Place the silicon carbide crucible containing the dried sample into a microwave catalytic instrument and carry out the microwave activation reaction in a nitrogen atmosphere; (4) After the reaction is complete, the sample is allowed to cool naturally to room temperature. The sample is then removed, washed until the washing solution is neutral, and dried to obtain a porous carbon material with high ethane adsorption selectivity.

2. The method for preparing porous carbon material with high ethane adsorption selectivity according to claim 1, characterized in that, In step (1), the mass ratio of commercial activated carbon, sodium hydroxide and sodium carbonate is 1.0:(0.5-2.0):(1.0-3.0).

3. The method for preparing porous carbon material with high ethane adsorption selectivity according to claim 1, characterized in that, In step (1), the ultrasonic treatment time is 5-15 minutes, preferably 10 minutes.

4. The method for preparing porous carbon material with high ethane adsorption selectivity according to claim 1, characterized in that, In step (2), the drying temperature is 60-100℃ and the drying time is 4-8 hours.

5. The method for preparing porous carbon material with high ethane adsorption selectivity according to claim 1, characterized in that, In step (3), the nitrogen purging flow rate is 50-150 mL / min and the purging time is 10-30 minutes.

6. The method for preparing porous carbon material with high ethane adsorption selectivity according to claim 1, characterized in that, In step (3), the output power of the microwave catalyst is 500-800W; the microwave irradiation activation time is 5-20 minutes.

7. The method for preparing porous carbon material with high ethane adsorption selectivity according to claim 1, characterized in that, In step (4), the product is washed with hydrochloric acid and deionized water in sequence. The concentration of hydrochloric acid is 0.5-2.0 mol / L. The drying temperature is 60-100℃ and the drying time is 4-8 hours.

8. A porous carbon material with high ethane adsorption selectivity, characterized in that, It is prepared by the preparation method according to any one of claims 1-7.

9. The application of the porous carbon material with high ethane adsorption selectivity as described in claim 8 in the adsorption and separation of a mixture of ethane and ethylene gases.

10. The application of the porous carbon material with high ethane adsorption selectivity according to claim 8 in the adsorption and separation of a mixture of ethane and ethylene gases, characterized in that, The porous carbon material exhibits preferential adsorption of ethane, and under conditions of 25°C and 1.0 bar, the adsorption selectivity for an equimolar mixture of ethane and ethylene is not less than 4.0; the adsorption capacity for ethane is not less than 4.0 mmol / g.

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