Process for modifying carbon molecular sieve

Abstract

The invention relates to a method for modifying a carbon molecular sieve. The method for modifying a carbon molecular sieve according to one embodiment of the present invention can: introduce an effective inorganic thin film into pores of a carbon molecular sieve; the process is carried out at a lower temperature than a conventional CVD process while still uniformly forming a thin film; the change of the adsorption amount depending on the gas type is controlled by finely controlling the pore size of the carbon molecular sieve; thus, separation selectivity depending on the type of gas is increased; and minimizing a compromise in which the specific surface area is significantly reduced, thereby maximizing the gas adsorption capacity even when the pore size of the carbon molecular sieve is reduced.

Description

Technical Field

[0001] The present disclosure relates to a method for modifying a carbon molecular sieve. Specifically, the present disclosure relates to a method for modifying a carbon molecular sieve to control the pore size of the carbon molecular sieve. Background Art

[0002] Carbon molecular sieve (CMS) (a special grade of activated carbon (AC)) is a kind of activated carbon with a measured value of or dozens Carbon molecular sieves are microporous carbon materials characterized by a uniform and narrow distribution of micropore sizes, and have attracted attention as materials that exhibit high permeability and selectivity properties. Carbon molecular sieves are primarily used for gas separation by pressure swing adsorption (PSA) processes and are used as adsorbents in the form of pellets or powders. The gas permeation, separation and adsorption properties of these carbon molecular sieves are determined by the size and shape of the micropores present in them.

[0003] Conventionally, in order to control the micropores present in carbon molecular sieves, various attempts have been made using carbon CVD using benzene, methane, etc. However, there is a problem in that it is difficult to control the diffusion and reaction inside the pores due to the difficulty in controlling process variables under high process temperature conditions of more than 600°C required for carbon CVD, and the technical difficulty is very high. Therefore, it is extremely difficult to accurately control the micropores in the carbon molecular sieve, and in addition, in the case of existing thermal CVD processes, minimizing the tradeoff of significantly reducing the specific surface area together with the control of the pore size is still a problem that must be solved. Therefore, a new concept of pore modification technology that solves the above problems is needed. Summary of the invention

[0004] Technical issues

[0005] The present disclosure aims to provide a modification method capable of controlling the micropore size of carbon molecular sieves.

[0006] Technical Solution

[0007] The present invention provides a method for modifying a carbon molecular sieve, which is performed for 2 or more cycles, and the cycles include: introducing a carbon molecular sieve and a first precursor into a reaction chamber to form a first precursor multilayer in which at least a portion of the first precursor is adsorbed into the pores of the carbon molecular sieve (step 1); purging the interior of the reaction chamber to remove unadsorbed first precursors from the first precursor multilayer to form a first precursor monolayer (step 2); introducing a second precursor into the reaction chamber to react the first precursor monolayer with at least a portion of the second precursor to form a composite layer (step 3); and purging the interior of the reaction chamber to remove unreacted second precursors from the composite layer to form an inorganic thin film (step 4).

[0008] According to one embodiment of the present invention, step 1 may include a step of introducing a carbon molecular sieve and a first precursor into a reaction chamber (step 1-1), and a step of impregnating the first precursor into the carbon molecular sieve to form a first precursor multilayer having at least a portion of the first precursor adsorbed on the carbon molecular sieve (step 1-2).

[0009] In addition, step 3 may include a step of introducing a second precursor into a reaction chamber (step 3-1), and a step of impregnating the second precursor into a carbon molecular sieve having a first precursor monolayer formed in its pores to form a composite layer in which the first precursor monolayer and at least a portion of the second precursor react (step 3-2).

[0010] Furthermore, in step 1-2, the time for impregnating the first precursor may be 1 second to 630 seconds, and the pressure may be 1 Torr to 10 Torr.

[0011] Furthermore, in step 3-2, the time for impregnating the second precursor may be 1 second to 630 seconds, and the pressure may be 1 Torr to 10 Torr.

[0012] Furthermore, in step 1, the introduction of the first precursor may be performed for 1 second to 600 seconds.

[0013] Furthermore, in step 3, the introduction of the second precursor may be performed for 1 second to 600 seconds.

[0014] Furthermore, the purging in step 2 and step 4 may be performed independently for 1 second to 600 seconds.

[0015] Furthermore, during the above cycles, the temperature of the carbon molecular sieve may be maintained at 80°C to 300°C.

[0016] In addition, the first precursor may include at least one selected from trimethylaluminum, diethylzinc, zinc acetate, tetrakis(dimethylamino)tin(IV), butoxytris(ethylmethylamido)hafnium, titanium isopropoxide, and diisopropylaminosilane.

[0017] In addition, the second precursor may include a2 O, O 3 , H 2 O plasma, O 3 Plasma and O 2 At least one of the plasmas.

[0018] In addition, in one or more of steps 2 and 4, the gas used for purging may include nitrogen (N 2 ) or argon (Ar).

[0019] Furthermore, the cycle can be performed from 2 to 320 cycles.

[0020] Beneficial Effects

[0021] The carbon molecular sieve modified according to an exemplary embodiment of the present disclosure may form an inorganic material thin film on the pore surface thereof.

[0022] The method according to an exemplary embodiment of the present disclosure may control the change in adsorption amount according to the gas type by finely controlling the pore size, and thus may increase the separation selectivity according to the gas type.

[0023] The method according to an exemplary embodiment of the present disclosure may be performed under lower temperature conditions than a conventional chemical vapor deposition (CVD) method, and the process may be precisely controlled.

[0024] The method according to an exemplary embodiment of the present disclosure can maximize the gas adsorption capacity even when the pore size is reduced by minimizing the tradeoff of a significant decrease in specific surface area.

[0025] The method according to an exemplary embodiment of the present disclosure may control the pores of the carbon molecular sieve to effectively sieve various gas molecules according to their sizes.

[0026] The method according to an exemplary embodiment of the present disclosure controls the pore size of the carbon molecular sieve to within Angstroms. level, and in particular, the pore size distribution in the microporous region can be controlled.

[0027] The method according to an exemplary embodiment of the present disclosure can introduce an effective inorganic thin film into the pores of a carbon molecular sieve and form the thin film more uniformly than the existing CVD process. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The gas adsorption amounts measured in Experimental Example 1 are shown.

[0029] Figure 2The pore volume distribution according to the pore width of Experimental Example 1 measured using the HK model is shown.

[0030] Figure 3 The pore volume distribution according to the pore width of Experimental Example 1 measured using the NLDFT model is shown.

[0031] Figure 4 A graph showing the measurement of the BET surface area of ​​Experimental Example 1 is shown.

[0032] Figure 5 The HK median pore width graph of Experimental Example 1 is shown.

[0033] Figure 6 The gas adsorption amounts measured in Experimental Example 2 are shown.

[0034] Figure 7 The pore volume distribution according to the pore width of Experimental Example 2 measured using the HK model is shown.

[0035] Figure 8 The pore volume distribution according to the pore width of Experimental Example 2 measured using the NLDFT model is shown.

[0036] Fig. 9 A graph showing the measurement of the BET surface area of ​​Experimental Example 2 is shown.

[0037] Fig.10 The HK median pore width graph of Experimental Example 2 is shown.

[0038] Fig.11 The gas adsorption amounts measured in Experimental Example 3 are shown.

[0039] Fig.12 The pore volume distribution according to the pore width of Experimental Example 3 measured using the HK model is shown.

[0040] Fig.13a and Fig.13b The pore volume distribution according to the pore width of Experimental Example 3 measured using the NLDFT model is shown.

[0041] Fig.14 A graph showing the measurement of the BET surface area of ​​Experimental Example 3 is shown.

[0042] Fig.15 The HK median pore width graph of Experimental Example 3 is shown.

[0043] Fig.16 It shows that N 2 Gas and O 2 Gas adsorption selectivity.

[0044] Fig.17 Experimental Example 4 shows the use of CO 2Gas adsorption data.

[0045] Fig.18 A graph showing the gas adsorption amount of Experimental Example 5.

[0046] Fig.19 The BET surface area graph of Experimental Example 5 is shown.

[0047] Fig. 20 The pore volume distribution according to the pore width of Experimental Example 5 measured using the NLDFT model is shown.

[0048] Fig.21 The pore volume distribution according to the pore width of Experimental Example 5 measured using the HK model is shown.

[0049] Fig. 22 The HK median pore width graph of Experimental Example 5 is shown.

[0050] Fig.23 The gas adsorption amount and BET surface area of ​​Experimental Example 6 are shown.

[0051] Fig.24 The pore volume distribution according to the pore width of Experimental Example 6 measured using the NLDFT model is shown.

[0052] Fig.25 The pore volume distribution according to the pore width of Experimental Example 6 measured using the HK model is shown.

[0053] Fig.26 The HK median pore width graph of Experimental Example 6 is shown. DETAILED DESCRIPTION

[0054] In the present invention, terms such as first and second are used to describe various components, and the above terms are used only for the purpose of distinguishing one component from another.

[0055] In addition, the terms used herein are only used to illustrate exemplary embodiments and are not intended to limit the present invention. Unless the context clearly indicates otherwise, expressions in the singular include expressions in the plural. It should be understood that the terms "comprise or include", "provide" or "have" in this specification are intended to specify the features, quantities, steps, components and / or combinations thereof that are implemented, but do not exclude the possibility of the presence or addition of one or more other features, quantities, steps, components, or combinations thereof.

[0056] In addition, in the present invention, when each layer or element is referred to as being formed "on" or "over" the corresponding layer or element, it means that each layer or element is directly formed on each layer or element, or another layer or element may be additionally formed between each layer, on the object, or on the substrate.

[0057] The present invention may have various modifications and may take various forms, and its specific embodiments are illustrated and described in detail below. However, it is not intended to limit the present invention to any specific form disclosed, and it should be understood that the scope of the present invention includes all modifications, equivalents and alternatives included in the thought and scope of the present invention.

[0058] The term molecular sieve is a trade name for synthetic zeolites manufactured by the American company Linde Industries. Molecular sieves have a large number of pores with uniform diameters and therefore have excellent adsorption capacity, and as their name indicates, they can have the function of sieving molecules. Today, the term molecular sieve has become a popular term and is used as a scientific term to refer to a porous material with three-dimensionally arranged pores of uniform size. Molecular sieves show selectivity for molecules of a specific size due to their uniform pore size and can therefore be widely used as catalysts, catalyst supports and adsorbents.

[0059] Carbon molecular sieve (CMS) is a molecular sieve whose main component is carbon. Carbon molecular sieve has many advantages over metal oxide molecular sieves such as zeolites, including high thermal stability, hydrothermal stability, chemical resistance and organic affinity. Carbon molecular sieves can also be used in various applications such as catalyst supports, adsorbents, sensors and electrode materials. According to the pore size of the carbon molecular sieve, gases are classified into those affected by the sieving effect and those not affected by the sieving effect. For example, since the kinetic diameter of methane is (0.38 nm), and the kinetic diameter of nitrogen is (0.364nm), so carbon molecular sieves with pore sizes between them can be used as the most effective methane / nitrogen molecular sieves. The process of synthesizing carbon molecular sieves generally involves a pyrolysis process, and methods are being designed to increase the pore size and porosity by pyrolysis temperature control and post-pyrolysis process treatment with oxygen, etc., but there are limitations to this increase.

[0060] Therefore, the inventors of the present invention attempted to finely adjust the pore size of a carbon molecular sieve while maintaining the specific surface area by applying atomic layer deposition (ALD) as a separate process to the prepared carbon molecular sieve.

[0061] Atomic layer deposition (ALD) offers many advantages over conventional deposition methods. ALD has the advantages of providing precise thickness control, excellent conformality, and uniformity over large areas by relying on self-limiting surface reactions. Atomic layer deposition is mainly used in semiconductor wafer processes, where the ALD process includes a cycle comprising the following sequential steps: 1) a step of adsorbing a precursor on the surface of a substrate; 2) a step of purging excess precursor molecules in the gas phase; 3) a step of introducing a reactant that reacts with the precursor on the surface of the substrate; and 4) a step of purging excess reactants. By performing the above steps as a cycle, the deposition thickness can be precisely controlled by counting the number of cycles.

[0062] According to an exemplary embodiment of the present invention, a method for modifying a carbon molecular sieve is performed for 2 or more cycles, and the cycles include: a step of introducing a carbon molecular sieve and a first precursor into a reaction chamber to form a first precursor multilayer in which at least a portion of the first precursor is adsorbed into the pores of the carbon molecular sieve (step 1); a step of purging the interior of the reaction chamber to remove unadsorbed first precursors from the first precursor multilayer to form a first precursor monolayer (step 2); a step of introducing a second precursor into the reaction chamber to react the first precursor monolayer with at least a portion of the second precursor to form a composite layer (step 3); and a step of purging the interior of the reaction chamber to remove unreacted second precursors from the composite layer to form an inorganic thin film (step 4).

[0063] In step 1, the first precursor is introduced into the reaction chamber together with the carbon molecular sieve, and at least some of the introduced first precursor is adsorbed into the pores of the carbon molecular sieve, and the first precursor that is not adsorbed is laminated into multiple layers, thereby forming a first precursor multilayer. In the subsequent step 2, the non-adsorbed first precursor in the first precursor multilayer can be removed by purging the interior of the reaction chamber, so that only the first precursor layer adsorbed on the pore surface of the carbon molecular sieve is retained, thereby forming a first precursor monolayer. Then, in step 3, the second precursor is introduced into the reaction chamber, and the first precursor monolayer and at least a portion of the second precursor are reacted, and the second precursor that has not reacted with the first precursor monolayer is arranged on the reactant, thereby forming a composite layer. In the subsequent step 4, the unreacted second precursor that has not reacted with the first precursor monolayer in the composite layer can be removed by purging the interior of the reaction chamber, thereby forming an inorganic film on the pore surface of the carbon molecular sieve.

[0064] Furthermore, the present invention performs steps 1 to 4 as one cycle, and performs the cycles two or more times.

[0065] Meanwhile, preferably, the cycle can be performed for 2 to 320 cycles, and more preferably, the cycle can be performed for 2 to 200 cycles. If the above cycle is performed less than 2 times, there may be a problem that the pores of the carbon molecular sieve are almost not modified due to insufficient deposition, and if the above cycle is performed for more than 320 cycles, a large number of closed pores may appear in the pores of the carbon molecular sieve, which may cause a problem of greatly reduced surface area and reduced adsorption efficiency.

[0066] According to one embodiment of the present invention, step 1 may include a step of introducing a carbon molecular sieve and a first precursor into a reaction chamber (step 1-1), and a step of impregnating the first precursor into the carbon molecular sieve to form a first precursor multilayer having at least a portion of the first precursor adsorbed on the carbon molecular sieve (step 1-2).

[0067] The impregnation in the above steps 1-2 is carried out by stopping the introduction of the first precursor into the reaction chamber and maintaining this state for a predetermined period of time, so that by performing the impregnation step, the first precursor multilayer can be uniformly formed in the pores of the carbon molecular sieve, and the first precursor multilayer can also be formed in the pores inside the carbon molecular sieve, thereby providing sufficient time for the precursor to be delivered to the micropores inside the carbon molecular sieve, and the pore size of the carbon molecular sieve can be more effectively and uniformly controlled.

[0068] In this case, the time for impregnating the first precursor may be 1 second to 630 seconds, and the pressure may be 1 torr to 10 torr, and preferably, the time for impregnating the first precursor may be 50 seconds to 600 seconds, and the pressure may be 2 torr to 8 torr. When the time and pressure ranges for impregnating the first precursor are met, the first precursor multilayer is uniformly formed in the pores of the carbon molecular sieve, and the first precursor multilayer is also formed in the pores inside the carbon molecular sieve, thereby giving the first precursor enough time to be delivered to the micropores inside the carbon molecular sieve, which may be more advantageous in effectively and uniformly controlling the pore size of the carbon molecular sieve.

[0069] In addition, according to one embodiment of the present invention, step 3 may include a step of introducing a second precursor into a reaction chamber (step 3-1), and a step of impregnating the second precursor into a carbon molecular sieve having a first precursor monolayer formed in its pores to form a composite layer in which the first precursor monolayer and at least a portion of the second precursor react (step 3-2).

[0070] The impregnation in the above step 3-2 is carried out by stopping the introduction of the second precursor into the reaction chamber and maintaining this state for a predetermined period of time, so that by performing the impregnation step, a composite layer can be uniformly formed on the first precursor monolayer on the pores of the carbon molecular sieve, and the composite layer can also be formed on the first precursor monolayer on the pores inside the carbon molecular sieve, thereby providing sufficient time for the precursor to be delivered to the micropores inside the carbon molecular sieve, and the pore size of the carbon molecular sieve can be more effectively and uniformly controlled.

[0071] In this case, the time for impregnating the second precursor may be 1 second to 630 seconds, and the pressure may be 1 torr to 10 torr, and preferably, the time for impregnating the second precursor may be 50 seconds to 600 seconds, and the pressure may be 2 torr to 8 torr. When the time and pressure ranges for impregnating the second precursor are met, a composite layer is uniformly formed on the first precursor monolayer on the pores of the carbon molecular sieve, and the composite layer is also formed on the first precursor monolayer on the pores inside the carbon molecular sieve, thereby giving the second precursor enough time to be delivered to the micropores inside the carbon molecular sieve, which may be more advantageous in effectively and uniformly controlling the pore size of the carbon molecular sieve.

[0072] Meanwhile, the introduction of the first precursor in step 1 may be performed for 1 second to 600 seconds, and the introduction of the second precursor in step 3 may be performed for 1 second to 600 seconds.

[0073] Specifically, the precursor introduction time of step 1 and step 3 can be each independently 1 second or longer, 2 seconds or longer, 5 seconds or longer, 10 seconds or longer, or 15 seconds or longer to 600 seconds or shorter, 300 seconds or shorter, 100 seconds or shorter, 50 seconds or shorter, or 20 seconds or shorter.

[0074] By controlling the precursor introduction time within the above range, the pore size of the carbon molecular sieve can be controlled according to the type of gas to be selected. However, if the precursor introduction time is shorter than 1 second, the pore control may not be effective due to incomplete atomic layer deposition, and if the precursor introduction time exceeds 600 seconds, many closed pores may appear in the pores of the carbon molecular sieve, which may greatly reduce the surface area and reduce the adsorption efficiency.

[0075] The purge times of step 2 and step 4 may each independently be 1 second to 1000 seconds, and for example, the purge times of step 2 and step 4 may each independently be 1 second or longer, 5 seconds or longer, 10 seconds or longer, 15 seconds or longer, 30 seconds or longer, or 60 seconds or longer to 1000 seconds or shorter, 900 seconds or shorter, 800 seconds or shorter, 700 seconds or shorter, or 600 seconds or shorter.

[0076] If the purge time is too short, residues of the precursor may remain, resulting in the deposition of an inorganic oxide film thicker than expected, while if the purge time exceeds the above range, it may lead to a decrease in process efficiency.

[0077] During the above cycle, the temperature of the carbon molecular sieve may be maintained at 80°C to 300°C, and preferably, the temperature of the carbon molecular sieve may be maintained at 90°C to 190°C.

[0078] By controlling the temperature of the carbon molecular sieve within the above range, the pore size of the carbon molecular sieve can be controlled according to the type of gas to be selected. If the temperature of the carbon molecular sieve is lower than 80°C, defects may occur in the formed inorganic film due to incomplete reaction, and if the temperature exceeds 300°C, an excessive amount of inorganic film may be formed in the pores of the carbon molecular sieve, which may result in a significant reduction in the surface area of ​​the carbon molecular sieve and a reduction in adsorption efficiency.

[0079] Meanwhile, the inorganic thin film formed in the pores of the carbon molecular sieve by performing the above cycle may include at least one of an oxide of the first precursor and a nitride of the first precursor.

[0080] The first precursor may include at least one selected from trimethylaluminum, diethylzinc, zinc acetate, tetrakis(dimethylamino)tin(IV), butoxytris(ethylmethylamido)hafnium, titanium isopropoxide, and diisopropylaminosilane. Preferably, in order to achieve the desired effect of the present invention, it may be advantageous for the first precursor to include trimethylaluminum.

[0081] The second precursor may be, but is not limited to, any material capable of reacting with the first precursor to form an oxide or nitride of the first precursor, but may include a material selected from H 2 O, O 3 , H 2 O plasma, O 3 Plasma and O 2 At least one of the plasmas may therefore be advantageous in achieving the desired effects of the present invention.

[0082] The gas used for purging in at least one of step 2 and step 4 may be used without limitation as long as the gas can be commonly used for purging in the art, but may preferably include nitrogen (N 2 ) or argon (Ar).

[0083] Embodiments of the invention

[0084] Hereinafter, preferred embodiments are presented to help understand the invention. However, the following embodiments are for illustrative purposes only, and the present invention is not limited thereto.

[0085] Hereinafter, activated carbon was used as the carbon molecular sieve, and the following Experimental Examples were performed with the following Experimental Example cycle as one cycle.

[0086] Experimental cycle

[0087] (Step 1)

[0088] The base pressure of the reaction chamber is maintained at a vacuum level of 40 mTorr or less. An activated carbon (carbon molecular sieve) substrate and trimethylaluminum as a first precursor are introduced into the reaction chamber. In this case, trimethylaluminum is vaporized outside the reaction chamber and introduced into the reaction chamber in a gaseous form (introduction time 2 seconds) to form a first precursor multilayer in which at least a portion of the first precursor is adsorbed into the pores of the carbon molecular sieve.

[0089] (Step 2)

[0090] Then, nitrogen (N 2 ) gas is purged inside the reaction chamber for 60 seconds to remove the unadsorbed first precursor from the first precursor multilayer, leaving only the first precursor layer adsorbed on the surfaces of the pores of the carbon molecular sieve, thereby forming a first precursor monolayer.

[0091] (Step 3)

[0092] Then, the second precursor H 2 O is introduced into the reaction chamber to react the first precursor monolayer with at least some of the second precursor to form a composite layer. At this time, the second precursor is also vaporized outside the chamber and introduced in gaseous form, and the introduction time is set to 2 seconds. In this process, the second precursor in contact with the first precursor monolayer reacts, and the unreacted second precursor is placed on the reactant to form a composite layer.

[0093] (Step 4)

[0094] Next, nitrogen (N 2 ) gas is purged inside the reaction chamber for 60 seconds to remove unreacted second precursor, thereby forming an inorganic thin film (oxide of the first precursor).

[0095] During steps 1 to 4, the activated carbon temperature was maintained at 150°C.

[0096] In addition, in the following experimental examples, the gas adsorption amount, pore volume distribution according to pore width, BET surface area, HK median pore width, and IAST adsorption selectivity were generally performed using the following methods.

[0097] Gas adsorption

[0098] To measure the gas adsorption, the samples were thoroughly degassed at 300 °C for 6 hours or longer, and then the relative pressure was increased from 1*e to 1*e using a 3Flex device from Micromeritics.-7 When the temperature was changed to 1, N 2 Gas adsorption was performed with Ar gas, and the amount of gas adsorbed in the sample was measured volumetrically.

[0099] Pore ​​volume distribution according to pore width

[0100] The pore size distribution was determined using nonlocal density functional theory (NLDFT) and the Horvath-Kawazoe slit pore model from adsorption isotherms.

[0101] BET surface area

[0102] The BET surface area was calculated from the adsorption isotherms using the Brunauer-Emmett-Teller equation.

[0103] HK median hole width

[0104] The HK median pore width value is determined by calculating the median value from the pore size distribution results using the Horvath-Kawazoe slot pore model.

[0105] IAST adsorption selectivity

[0106] In the following experimental example, the IAST adsorption selectivity is O 2 Gas relative to N 2 The adsorption selectivity of gases was measured using a Belsorp HP instrument at 120 kPa and 298.15 K for O 2 and N 2 After that, the air separation (N 2 :O 2 =79:21) in the ideal adsorption solution theory (IAST) 2 、N 2 Selective.

[0107]

[0108] In the above IAST adsorption selectivity equation, represents the oxygen adsorption pressure, Indicated in The oxygen adsorption under represents the nitrogen adsorption pressure, and Indicated in Nitrogen adsorption pressure.

[0109] Experimental Example 1: Confirmation of physical properties according to the change of atomic layer deposition cycle number

[0110] The above experimental example was cycled once, 30 times, 100 times and 300 times to obtain modified activated carbon. The gas adsorption amount, pore volume distribution according to pore width, BET surface area and HK median pore width of the modified activated carbon were confirmed by the above method.

[0111] according to Figure 1 , confirming that as the cycle proceeds and the modification occurs more times, i.e., as more precursors are deposited in the pores of the activated carbon, the amount of adsorbed gas decreases compared to the activated carbon before modification.

[0112] By using the HK model Figure 2 From the graph of ALD cycles, it can be confirmed that the pores in the micropore region of 2 nm or less have changed. In particular, there is no significant change in the region of less than or equal to 0.5 nm, but in the region of pores greater than 0.5 nm, an overall decrease in pore size is observed as the number of ALD cycles increases.

[0113] In addition, the observations analyzed by the NLDFT model Figure 3 , confirming that the pores in the micropore to mesopore region decrease overall with increasing process cycles. In particular, in the figure that magnifies the micropore region of 2 nm or less, there is no significant change in the ultramicropore region of 0.5 nm or less, but the micropore region of 1 nm to 2 nm shows a significant decrease, indicating that the proportion of large-sized pores decreases and the proportion of relatively small-sized pores increases with the application of the ALD process. However, when a very thick ALD process of 300 cycles is applied, the ultramicropore region decreases significantly, indicating that the excess Al 2 O 3 Overall pore closure occurs with deposition of the film.

[0114] By inspection Figure 4 The BET surface area in the 2D-type MgO2O3 matrix confirms that the surface area decreases with increasing cycle number and modification. Figure 5 When the median pore width is calculated from the HK median pore width graph, it is confirmed that the average width decreases with increasing ALD cycles. In this case, when 1 cycle is performed, it is confirmed that there is almost no difference in specific surface area compared to when no cycle is performed, but the pore width is greatly reduced.

[0115] Experimental Example 2: Confirmation of physical properties based on precursor injection time

[0116] The experimental example cycle was performed in the same manner as the above experimental example cycle, except that the first precursor injection time was changed to 15 seconds, the second precursor injection time was changed to 15 seconds, and the purge time between each precursor injection was changed to 600 seconds. The experimental example cycle was performed 10 times to obtain modified activated carbon. That is, although the precursor injection time was significantly increased, the number of cycle repetitions was reduced to 1 / 10, and the total process time was kept similar to the total process time of the 100 cycle experiment in Experimental Example 1.

[0117] The gas adsorption amount, pore volume distribution according to pore width, BET surface area and HK median pore width of the modified activated carbon were confirmed by the above methods.

[0118] As in Experimental Example 1, after 10 cycles, it was confirmed that the gas adsorption amount of the modified activated carbon was reduced compared with the gas adsorption amount of the unmodified activated carbon (see Figure 6 ). In addition, it was confirmed that even if the total process time was similar and the total injected precursor amount was similar, maintaining the precursor injection time for a long time helped the ALD precursor to penetrate into the activated carbon having a complex porous structure and be effectively deposited in the pores inside the activated carbon.

[0119] By using the HK model Figure 7 , the change in pores in the micropore region of 2 nm or less can be confirmed. In particular, there is no significant change in the region of less than or equal to 0.4 nm, but in the region of pores greater than 0.4 nm, an overall decrease in pore size is observed as the number of ALD cycles increases. This means that the size of pores of even slightly smaller size than in Experimental Example 1 is greatly reduced, and it seems that pore control is possible over a wider range overall.

[0120] In addition, in the analysis of the NLDFT model Figure 8 , it can be confirmed that the volume of micropores and mesopores larger than 0.5 nm is effectively reduced, and the volume of ultramicropores smaller than 0.5 nm is maintained.

[0121] Confirmed Fig. 9 The BET surface area also shows that the surface area of ​​the modified activated carbon is reduced compared to that of the unmodified activated carbon.

[0122] In addition, when the calculation is based on Fig.10 When the median value of the pore width of the HK median pore width graph is taken, an average width reduction similar to the average width reduction in the 300-cycle process of Experimental Example 1 is confirmed in the 10-cycle ALD process.

[0123] In particular, it was confirmed that the change in injection time affects the gas adsorption amount and BET surface area when comparing Experimental Example 1 and Experimental Example 2. It is considered that the longer the injection time, the more uniform the distribution and deposition in the carbon precursor, which has an influence.

[0124] Experimental Example 3: Confirmation of physical properties depending on whether a precursor impregnation step is included

[0125] First, the physical properties of unmodified activated carbon and activated carbon modified by adding a precursor impregnation step to the experimental cycle were compared.

[0126] In the method for modification including the precursor impregnation step of this experiment, the same steps as the experimental example cycle are performed, except that it also includes a step of increasing the pressure for 24 seconds after introducing the first precursor in (step 1) to reach a chamber pressure of 5 Torr, and then impregnating for 600 seconds, and a step of increasing the pressure for 27 seconds after introducing the second precursor in (step 3) to reach a chamber pressure of 5 Torr, and then impregnating for 600 seconds, and the purge time in (step 2) and (step 4) is set to 10 seconds, and a step of evacuating the reaction chamber for 60 seconds without purging is added.

[0127] The activated carbon was modified by performing five experimental cycles including an impregnation step. Afterwards, the gas adsorption capacity, pore volume distribution according to pore width, BET surface area and HK median pore width of the modified activated carbon were determined by the above methods.

[0128] Furthermore, the immersion pressure was changed from 5 Torr to 0.5 Torr, 1 Torr, and 3 Torr, respectively, and the physical properties were measured after fabrication, and the immersion time was changed from 600 seconds to 0.5 seconds, 300 seconds, and 1200 seconds, respectively, and the physical properties were measured after fabrication.

[0129] As a result, it was confirmed that Fig.11 a and Fig.11 In the experimental example cycle including the impregnation step shown in b, the gas adsorption amount of the modified activated carbon was reduced compared with the gas adsorption amount of the unmodified activated carbon, and it was confirmed that the higher the impregnation pressure and the longer the impregnation time, the more the amount of adsorbed gas decreased. In addition, it was confirmed that when the impregnation pressure was 0.5 Torr and the impregnation time was 0.5 seconds, the difference in the amount of adsorbed gas was the smallest compared with when it was not performed.

[0130] As in Experimental Example 2, by using the HK model analysis Fig.12 a and Fig.12b, it is possible to confirm the change in pores in the micropore region of 2 nm or less. In particular, there is no significant change in the region of less than or equal to 0.3 nm, but in the region of pores greater than 0.3 nm, an overall decrease in pore size is observed as the immersion pressure and immersion time increase. This confirms that even slightly smaller pores are significantly reduced compared to Experimental Example 2, and that pore control is possible over a wider range overall.

[0131] In addition, in the analysis of the NLDFT model Fig.13a and Fig.13b In the figure, it can be confirmed that the volume of micropores and mesopores larger than 0.45 nm is effectively reduced, and the volume of ultramicropores smaller than 0.45 nm is maintained. It was found that pore size control is possible even in the case of a less cycle process of 5 cycles, because when the impregnation process is introduced, the reactants can be effectively injected into the interior, and it was found that pore size control is possible by changing the impregnation pressure and the impregnation time.

[0132] Confirmed Fig.14 a and Fig.14 The BET surface area of ​​b also shows that the surface area of ​​the modified activated carbon is reduced compared with that of the unmodified activated carbon. In addition, it was confirmed that the surface area decreases with increasing impregnation pressure and impregnation time.

[0133] In particular, when Experimental Example 2 and Experimental Example 3 are compared, it is confirmed that the BET surface area is slightly reduced even if the number of cycles is reduced by including the immersion step (see Fig.15 ). In addition, as the immersion pressure and immersion time increased, a decrease in pore width was observed, and it was confirmed that when the immersion time was 0.5 seconds, the pore width decrease was minimal compared to that not performed (bare AC1).

[0134] Experimental Example 4: Confirmation of Selectivity of Gas Adsorption

[0135] The adsorption, IAST selectivity (i.e., adsorption selectivity), and adsorption capacity of unmodified activated carbon, modified activated carbon after 5 cycles including the impregnation step, and modified activated carbon after 100 cycles of the experimental example without the impregnation step of Experimental Example 1 were compared. Fig.16 As shown, it is confirmed that O 2 Gas relative to N 2 Gas adsorption selectivity.

[0136] according to Fig.16 , the adsorption selectivity of the activated carbon modified by performing 100 cycles without the impregnation step of Experimental Example 1 was the highest, and the activated carbon modified by performing 5 cycles including the impregnation step showed an adsorption selectivity similar to that of the unmodified activated carbon.

[0137] In addition, from Fig.17 Use of CO 2 The BET results can be used to make more specific inferences. 2 Observe that due to N 2 The ultra-micropore area smaller than 0.4 nm that cannot be measured due to the size of the Ar gas molecules. The results of 100 cycles of ALD show that the volume of micropores with a size of 0.36 nm increases compared to the 5 cycles including the immersion process. This is because in the process including the immersion process, the macropores become smaller and the micropores also become smaller, but in the process not including the immersion process, the macropores become smaller and ultra-micropores of 0.36 nm are generated, and the existing ultra-micropores are not greatly affected by the process.

[0138] Experimental Example 5: Confirmation of physical properties controlled by precursor injection time and purge time

[0139] The experiment was carried out in the same manner as the above experimental example cycle, except that the precursor injection time of (step 1) and (step 3) and the purge time of (step 2) and (step 4) were controlled as shown in the following table. The activated carbon was modified by performing 100 cycles with controlled precursor injection time and purge time, and the gas adsorption amount, pore volume distribution according to pore width, BET surface area and HK median pore width were determined.

[0140] [Table 1]

[0141]

[0142] The classification in Table 1 above is used in the same way in the following figure.

[0143] according to Fig.18 , it was confirmed that the amount of adsorbed gas decreased as the introduction time of the first precursor and the second precursor increased. In this case, when the precursor introduction time was 0.5 seconds, the difference in the amount of adsorbed gas was the smallest compared to when it was not performed (bare AC1).

[0144] observe Fig.19 The BET surface area plots confirm that the surface area is hardly affected by the increase in purge time, but when the precursor is introduced for a certain period of time or longer, the surface area decreases rapidly, and therefore, the gas adsorption amount decreases (5-30-5-30). Also, when the precursor introduction time is 0.5 seconds, the difference in surface area is minimal compared to when it is not (bare AC1).

[0145] Furthermore, like BET, the change in pore width is not greatly affected by changes in purge time. Fig. 20 a and Fig. 20b, when the purge time was shortened to 30 s compared to the existing 2-60-2-60 cycle, a smaller pore size due to the residual precursor was observed. In addition, when the precursor injection time was reduced to 0.5 s, the difference from the bare AC1 was minimal, and when the precursor injection time was increased to 5 s, a larger pore size reduction was observed, confirming that the precursor injection time has a greater impact on the deposition pattern.

[0146] based on Fig.21 Analysis of the results of the HK model of FIG. 4 also confirms that, similar to the NLDFT results above, more ALD film deposition occurs as the precursor injection time increases rather than due to changes in the purge time.

[0147] Fig. 22 The HK median pore width calculation results show that the average pores decrease with decreasing purge time and increasing precursor injection time, however, in the case of 5-30-5-30, the size of pores smaller than 0.5 nm also decreases due to excessive deposition, and the overall reduction of pores reduces the pore size reduction effect. In addition, for 0.5-30-0.5-30, the difference with bare AC1 is minimal.

[0148] Experimental Example 6: Confirmation of physical properties based on substrate temperature

[0149] The experiment was conducted in the same manner as the above experimental example cycle, but the substrate temperature was changed to 90° C., 150° C., and 210° C. The gas adsorption amount, pore volume distribution according to pore width, BET surface area, and HK median pore width of the activated carbon modified by conducting this cycle 100 times were determined respectively.

[0150] observe Fig.23 The BET surface area plot of , confirms that as the substrate temperature increases, the surface area tends to decrease and, likewise, the amount of gas adsorption decreases.

[0151] Based on the NLDFT model ( Fig.24 ) and HK model ( Fig.25 ) all clearly confirm that, as the substrate temperature increases, a decrease in pore size is observed, and in particular, a significant decrease in micropores is observed when the experiment is performed under the experimental condition of 210°C.

[0152] As Fig.26 The results of calculating the HK median pore width in , confirm that the overall pore size decreases with increasing temperature to 150 °C, but in the case of 210 °C, pores smaller than 0.5 nm also become smaller due to excessive deposition, and the overall reduction of the pores leads to a reduction in the pore size reduction effect.

Claims

1. A method for modifying a carbon molecular sieve, the method being carried out in 2 or more cycles, the cycle comprising: introducing a carbon molecular sieve and a first precursor into a reaction chamber, thereby forming a first precursor multi-layer in which at least a part of the first precursor is adsorbed into the pores of the carbon molecular sieve (step 1); purging the interior of the reaction chamber to remove the unadsorbed first precursor from the first precursor multi-layer, thereby forming a first precursor monolayer (step 2); introducing a second precursor into the reaction chamber to react the first precursor monolayer with at least a part of the second precursor, thereby forming a composite layer (step 3); and purging the interior of the reaction chamber to remove the unreacted second precursor from the composite layer, thereby forming an inorganic thin film (step 4).

2. The method for modifying a carbon molecular sieve according to claim 1, wherein said step 1 comprises: introducing a carbon molecular sieve and a first precursor into a reaction chamber (step 1-1); and impregnating the first precursor into the carbon molecular sieve to form a first precursor multi-layer having at least a part of the first precursor adsorbed on the carbon molecular sieve (step 1-2).

3. The method for modifying a carbon molecular sieve according to claim 1, wherein said step 3 comprises: introducing a second precursor into the reaction chamber (step 3-1); and impregnating the second precursor into the carbon molecular sieve having a first precursor monolayer formed in its pores, thereby forming a composite layer in which the first precursor monolayer and at least a part of the second precursor react (step 3-2).

4. The method for modifying a carbon molecular sieve according to claim 2, wherein in said step 1-2, the time for impregnating the first precursor is 1 second to 630 seconds, and the pressure is 1 Torr to 10 Torr.

5. The method for modifying a carbon molecular sieve according to claim 3, wherein in said step 3-2, the time for impregnating the second precursor is 1 second to 630 seconds, and the pressure is 1 Torr to 10 Torr.

6. The method for modifying a carbon molecular sieve according to claim 1, wherein in said step 1, the introduction of the first precursor is carried out for 1 second to 600 seconds.

7. The method for modifying a carbon molecular sieve according to claim 1, wherein in said step 3, the introduction of the second precursor is carried out for 1 second to 600 seconds.

8. The method for modifying a carbon molecular sieve according to claim 1, wherein the purging in said step 2 and said step 4 is carried out independently for 1 second to 600 seconds respectively.

9. The method for modifying a carbon molecular sieve according to claim 1, wherein during the above cycle, the temperature of the carbon molecular sieve is maintained at 80 °C to 300 °C.

10. The method for modifying a carbon molecular sieve according to claim 1, wherein the first precursor comprises at least one selected from trimethylaluminum, diethylzinc, zinc acetate, tetra(dimethylamino)tin(IV), butoxytris(ethylmethylcarbamoyl)hafnium, titanium isopropoxide, and diisopropylaminosilane.

11. The method for modifying a carbon molecular sieve according to claim 1, wherein the second precursor comprises at least one selected from H 2 O, O 3 H 2 O plasma, O 3 plasma, and O 2 plasma.

12. The method for modifying a carbon molecular sieve according to claim 1, wherein in one or more of the step 2 and the step 4, the gas used for purging comprises nitrogen (N 2 ) or argon (Ar).

13. The method for modifying a carbon molecular sieve according to claim 1, wherein the cycle is carried out 2 to 320 times.

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