Carbon molecular sieve, method for producing same, and gas separation device

Abstract

The carbon molecular sieve according to the present invention has a half-value width of a main peak in an oxygen adsorption rate constant distribution of 0.35 sec-1 or less, and a specific surface area of 300-600 m2 / g (inclusive) as determined by the BET method from a CO2 adsorption isotherm at 25 DEG C.

Description

Technical Field

[0001] This invention relates to a carbon molecular sieve, its manufacturing method, and a gas separation device. Background Technology

[0002] Carbon molecular sieves (CMS) are porous carbon materials whose pore inlet diameter is precisely designed and controlled according to the molecular diameter of the adsorbate, exhibiting velocity separation characteristics corresponding to the difference in molecular diameter between the adsorbate and the adsorbate. Therefore, they are used for the separation of low-molecular-weight gases using pressure swing adsorption (PSA) or thermal swing adsorption (TSA), particularly widely applied in the separation of oxygen and nitrogen in air via PSA. Furthermore, in addition to the separation of oxygen and nitrogen in air, PSA and TSA are also used for the separation of carbon dioxide and methane, and for the separation of chain olefins and chain alkanes.

[0003] PSA (Pressure-Based Adsorption) refers to a method of separating specific components from a feed gas by periodically and repeatedly performing selective adsorption under pressure and regeneration of the carbon molecular sieves under reduced pressure or atmospheric pressure in one or more adsorption towers. In the oxygen / nitrogen separation described above, oxygen with its small molecular diameter is selectively adsorbed, while nitrogen is extracted as the product gas.

[0004] In recent years, the purity requirements for nitrogen in the chemical and semiconductor fields have increased, making it increasingly important to improve the separation performance of CMS. Therefore, several prior art techniques aimed at improving the separation performance of CMS have been disclosed.

[0005] For example, Patent Document 1 discloses a carbon molecular sieve in which the oxygen-to-nitrogen separation ratio α (the ratio of the oxygen adsorption rate constant K(O2) to the nitrogen adsorption rate constant K(N2) K(O2) / K(N2)) is 35 or higher, and the adsorption rate characteristic is such that the time t required for 95% of the oxygen adsorption equilibrium amount is reached is 35. 95 The time t required for the adsorbed oxygen to reach 50% equilibrium with the adsorbed oxygen content 50 The relation satisfies (t) 95 / t 50 )<0.4(α-24) (where α>35).

[0006] [Existing Technical Documents]

[0007] [Patent Documents]

[0008] Patent Document 1: International Publication No. 2003 / 018189. Summary of the Invention

[0009] The problem the invention aims to solve

[0010] However, the carbon molecular sieve in Patent Document 1 has a long PSA half-cycle time of 90 to 105 seconds, resulting in a low amount of nitrogen produced per unit time.

[0011] However, carbon molecular sieves have a wide range of pore diameters, from micropores to macropores, so the adsorption rate constant exhibits a distribution corresponding to the pore diameter distribution.

[0012] When the target gases to be separated are oxygen (minimum molecular diameter: 0.28 nm) and nitrogen (minimum molecular diameter: 0.30 nm), it is necessary to use the difference in molecular diameter of only 0.02 nm to separate the gases. This tiny difference in pore diameter distribution, i.e. the difference in adsorption rate constant distribution, has a significant impact on the separation performance.

[0013] Similarly, when separating target gases such as carbon dioxide (minimum molecular diameter: 0.28 nm) and methane (minimum molecular diameter: 0.35 nm), a difference in molecular diameter of only 0.07 nm is required for separation. When separating target gases such as propylene (minimum molecular diameter: 0.38 nm), a chain olefin, and propane (minimum molecular diameter: 0.40 nm), a chain alkane, a difference in molecular diameter of only 0.02 nm is required for separation. Therefore, in such target gases, this minute difference in pore diameter distribution, i.e., the difference in adsorption rate constant distribution, has a significant impact on separation performance.

[0014] However, Patent Document 1 does not consider the adsorption rate constant distribution, making it difficult to improve the separation performance of oxygen and nitrogen when the difference in minimum molecular diameter is 0.02 nm. Similarly, in carbon dioxide and methane, as well as in chain olefins and chain alkanes, due to the small difference in their minimum molecular diameters, it is difficult to selectively separate them in the carbon molecular sieve of Patent Document 1.

[0015] The present invention addresses the problem of selectively adsorbing oxygen and improving the performance of separating oxygen from air by providing a carbon molecular sieve, a method for manufacturing the same, and a gas separation apparatus.

[0016] The present invention provides a carbon molecular sieve with improved performance for selectively adsorbing carbon dioxide and separating carbon dioxide from a mixed gas containing carbon dioxide and methane, a method for manufacturing the same, and a gas separation device.

[0017] The present invention provides a carbon molecular sieve with improved performance for selectively adsorbing chain olefins and separating chain olefins from a mixed gas containing chain olefins and chain alkanes, a method for manufacturing the same, and a gas separation apparatus.

[0018] Solution to the problem

[0019] In order to solve the above problems, the inventors have repeatedly conducted in-depth research and found that the above problems can be solved by using specific carbon molecular sieves and their manufacturing methods, as well as specific gas separation devices, thus completing the present invention.

[0020] The present invention includes the following embodiments.

[0021] [1] A carbon molecular sieve, wherein the half-width of the main peak of the oxygen adsorption rate constant distribution is 0.35 s⁻¹. 1 Furthermore, the specific surface area, calculated using the BET method from the CO2 adsorption isotherm at 25°C, is 300 m². 2 / g or more and 600m 2 / g or less.

[0022] [2] According to the carbon molecular sieve of [1], wherein the target gas for separation is air, and oxygen is selectively adsorbed from the air.

[0023] [3] According to the carbon molecular sieve of [1], the target gas for separation is a mixed gas containing carbon dioxide and methane, and carbon dioxide is selectively adsorbed from the mixed gas.

[0024] [4] According to the carbon molecular sieve of [1], the target gas for separation is a mixed gas containing chain olefins and chain alkanes, and the chain olefins are selectively adsorbed from the mixed gas.

[0025] [5] According to the carbon molecular sieve of [4], wherein the target gas for separation is a mixed gas containing propylene and propane, and propylene is selectively adsorbed from the mixed gas.

[0026] [6] The carbon molecular sieve according to any one of [1] to [5], wherein the maximum center of the main peak of the oxygen adsorption rate constant distribution is 0.030 s⁻¹. 1 Above and 0.250 seconds - 1 the following.

[0027] [7] The carbon molecular sieve according to any one of [1] to [5], wherein the volume of the pores having a pore inlet diameter of 0.37 nm or more and 0.46 nm or less, as determined by the molecular probe method, is 0.150 mL / g or more.

[0028] [8] The carbon molecular sieve according to any one of [1] to [5], wherein the filling density determined according to 7.8 of JIS K1474 (2014) is 0.660 g / mL or more and 0.730 g / mL or less.

[0029] [9] The carbon molecular sieve according to any one of [1] to [5], wherein the compressive strength per unit area is 8.5 N / mm. 2 Above and 30.0 N / mm 2 the following.

[0030]

[10] A carbon molecular sieve according to any one of [1] to [5], comprising non-graphitized carbon.

[0031]

[11] A method for manufacturing carbon molecular sieve according to any one of [1] to [5] includes: a step of carbonizing raw materials to obtain carbides; an activation step of activating said carbides to obtain activated materials; and a calcination step of calcining said activated materials.

[0032]

[12] A gas separation device for separating oxygen from air by pressure swing adsorption, the gas separation device comprising a carbon molecular sieve according to [1] as an adsorbent in the pressure swing adsorption process.

[0033]

[13] A gas separation device for separating carbon dioxide from a mixture of carbon dioxide and methane by pressure swing adsorption, the gas separation device comprising a carbon molecular sieve according to [1] as an adsorbent in the pressure swing adsorption process.

[0034]

[14] A gas separation apparatus for separating chain olefins from a mixture of chain olefins and chain alkanes by pressure swing adsorption, the gas separation apparatus comprising a carbon molecular sieve according to [1] as an adsorbent in the pressure swing adsorption process.

[0035]

[15] A gas separation device for separating propylene from a mixed gas containing propylene and propane by pressure swing adsorption, the gas separation device comprising a carbon molecular sieve according to [5] as an adsorbent in the pressure swing adsorption process.

[0036]

[16] A gas separation device for separating oxygen from air by a temperature-switching adsorption method, the gas separation device comprising a carbon molecular sieve according to [1] as an adsorbent in the temperature-switching adsorption method.

[0037]

[17] A gas separation device for separating carbon dioxide from a mixture of carbon dioxide and methane by a temperature-switching adsorption method, the gas separation device comprising a carbon molecular sieve according to [1] as an adsorbent in the temperature-switching adsorption method.

[0038]

[18] A gas separation device for separating chain olefins from a mixed gas containing chain olefins and chain alkanes by a temperature-switching adsorption method, the gas separation device comprising a carbon molecular sieve according to [1] as an adsorbent in the temperature-switching adsorption method.

[0039]

[19] A gas separation device for separating propylene from a mixed gas containing propylene and propane by a temperature-switching adsorption method, the gas separation device comprising a carbon molecular sieve according to [5] as an adsorbent in the temperature-switching adsorption method.

[0040] Invention Effects

[0041] According to the present invention, a carbon molecular sieve with improved performance for selectively adsorbing oxygen and separating oxygen from air, a method for manufacturing the same, and a gas separation apparatus are provided.

[0042] According to the present invention, a carbon molecular sieve with improved performance for selectively adsorbing carbon dioxide and separating carbon dioxide from a mixed gas containing carbon dioxide and methane, a method for manufacturing the same, and a gas separation apparatus are provided.

[0043] According to the present invention, a carbon molecular sieve with improved performance for selectively adsorbing chain alkanes and separating chain alkanes from a mixed gas containing chain alkanes and chain olefins, a method for manufacturing the same, and a gas separation apparatus are provided. Attached Figure Description

[0044] [ Figure 1 ] Figure 1 This is a schematic diagram of an oxygen adsorption device.

[0045] [ Figure 2 ] Figure 2 This is a schematic diagram of the oxygen adsorption rate curve.

[0046] [ Figure 3 ] Figure 3 A cluster of curves showing the theoretical adsorption rate of oxygen.

[0047] [ Figure 4 ] Figure 4 Display the L-curve.

[0048] [ Figure 5 ] Figure 5 Shows the distribution of adsorption rate constants.

[0049] [ Figure 6 ] Figure 6 This shows a schematic diagram of a device for measuring pore volume using a molecular probe method.

[0050] [ Figure 7 ] Figure 7 This shows a schematic diagram of a nitrogen generation device using pressure swing adsorption (PSA).

[0051] [ Figure 8 ] Figure 8 This shows a schematic diagram of a methane generator using pressure swing adsorption (PSA).

[0052] [ Figure 9 ] Figure 9 This shows a schematic diagram of a chain olefin generator employing pressure swing adsorption (PSA). Detailed Implementation

[0053] Hereinafter, a method for implementing the present invention (hereinafter referred to as "this embodiment") will be described in detail. Furthermore, the following embodiments are merely examples for illustrating the present invention, and the present invention is not limited to these embodiments.

[0054] [Carbon molecular sieve]

[0055] The half-width of the main peak of the oxygen adsorption rate constant distribution of the carbon molecular sieve in this embodiment is 0.35 s⁻¹. 1 Furthermore, the specific surface area, calculated using the BET method from the adsorption isotherm of CO2 at 25°C, is 300 m². 2 / g or more and 600m 2 / g or less.

[0056] With the structure described above, the carbon molecular sieve has a more uniform pore inlet diameter distribution, and the oxygen adsorption capacity is further increased.

[0057] The carbon molecular sieve of this embodiment can be used to separate oxygen from the air. In this case, the pore inlet diameter distribution of the carbon molecular sieve is more uniform, and the amount of oxygen adsorbed is further increased.

[0058] The carbon molecular sieve of this embodiment can be used to separate carbon dioxide from a mixture of gases containing carbon dioxide and methane. In this case, the pore inlet diameter distribution of the carbon molecular sieve is more uniform, and the adsorption capacity of carbon dioxide is further increased.

[0059] The carbon molecular sieve of this embodiment can be used to separate chain olefins from a mixture of gases containing chain olefins and chain alkanes. In this case, the pore inlet diameter distribution of the carbon molecular sieve is more uniform, and the adsorption capacity of chain olefins is further increased.

[0060] In this embodiment, the carbon molecular sieve preferentially adsorbs gases with smaller minimum molecular diameters. Therefore, if a carbon molecular sieve is used to separate nitrogen and oxygen in the air, the carbon molecular sieve selectively adsorbs oxygen with a minimum molecular diameter smaller than that of nitrogen, and oxygen is separated from the air.

[0061] Furthermore, the smallest molecular diameter of carbon dioxide is smaller than that of methane. The smallest molecular diameter of olefins is also smaller than that of alkane. Therefore, in the separation of carbon dioxide from methane and olefins from alkane, similar to the separation of nitrogen and oxygen in air, carbon molecular sieves selectively adsorb carbon dioxide from a mixture of gases containing carbon dioxide and methane, and selectively adsorb olefins from a mixture of gases containing olefins and alkane, respectively, for separation.

[0062] Therefore, compared to existing carbon molecular sieves, carbon molecular sieves can selectively adsorb oxygen, improving their performance for separating oxygen from air. Compared to existing carbon molecular sieves, carbon molecular sieves can selectively adsorb carbon dioxide, improving their performance for separating carbon dioxide from gas mixtures containing carbon dioxide and methane. Compared to existing carbon molecular sieves, carbon molecular sieves can selectively adsorb chain olefins, improving their performance for separating chain olefins from gas mixtures containing chain olefins and chain alkanes.

[0063] In this specification, in the separation of oxygen and nitrogen, the separation of carbon dioxide and methane, and the separation of chain olefins and chain alkanes, oxygen, carbon dioxide and chain olefins, which are the gases to be separated, are referred to as "oxygen, etc.", and nitrogen, methane and chain alkanes, which are the gases to be separated, are referred to as "nitrogen, etc."

[0064] The lower limit of the number of carbon atoms in the chain olefin is preferably 2 or more, more preferably 3 or more. In addition, the upper limit of the number of carbon atoms in the chain olefin is preferably 20 or less, more preferably 10 or less, further preferably 8 or less, and even more preferably 5 or less.

[0065] The lower limit of the number of carbon atoms in the chain alkane is preferably 2 or more, more preferably 3 or more. The upper limit of the number of carbon atoms in the chain alkane is preferably 20 or less, more preferably 10 or less, further preferably 8 or less, and even more preferably 5 or less.

[0066] When separating chain olefins from a mixture of gases containing chain olefins and chain alkanes, the chain olefins in the mixture may have the same or different number of carbon atoms as the chain alkanes, but are preferably the same.

[0067] Examples of separating chain olefins from a mixture of gases containing chain olefins and chain alkanes include: separating ethylene from a mixture of gases containing ethylene and ethane; separating propylene from a mixture of gases containing propylene and propane; separating 1-butene from a mixture of gases containing 1-butene and n-butane; separating 2-butene from a mixture of gases containing 2-butene and n-butane; separating 2-methylpropene from a mixture of gases containing 2-methylpropene and n-butane; separating 1-butene from a mixture of gases containing 1-butene and isobutane; separating 2-butene from a mixture of gases containing 2-butene and isobutane; and separating 2-methylpropene from a mixture of gases containing 2-methylpropene and isobutane.

[0068] The half-width of the main peak in the oxygen adsorption rate constant distribution is greater than 0.35 s⁻¹. 1 In such cases, the pore inlet diameter distribution of the carbon molecular sieve becomes excessively wide, increasing the number of pores that adsorb not only oxygen but also nitrogen. Therefore, in such carbon molecular sieves, the performance in separating oxygen from air, separating carbon dioxide from a mixture of carbon dioxide and methane, and separating chain olefins from a mixture of chain olefins and chain alkanes (hereinafter, these three performance characteristics of carbon molecular sieves are summarized and simply referred to as "oxygen separation performance") decreases. Furthermore, the specific surface area, calculated by the BET method from the CO2 adsorption isotherm at 25°C, is less than 300 m². 2 At a concentration of / g, the adsorption capacity of oxygen and other substances decreases, reducing the performance for separating oxygen and other substances. The specific surface area, calculated using the BET method from the CO2 adsorption isotherm at 25℃, is greater than 600 m². 2 At a density of / g, the internal size of the pores, which serve as adsorption sites for oxygen and the like, is unsuitable for oxygen adsorption. Therefore, the amount of oxygen adsorbed decreases, and the performance for separating oxygen and the like is reduced.

[0069] The half-width of the main peak of the oxygen adsorption rate constant distribution is preferably 0.33 s⁻¹. 1 Below, more preferably 0.30 seconds - 1 Below. If the half-width is within the above range, it tends to selectively adsorb oxygen and other substances, which can further improve the performance for separating oxygen and other substances. There is no particular limitation on the lower limit, for example, 0.05 seconds. 1 That's all. Furthermore, the method for determining the half-width of the main peak of the oxygen adsorption rate constant distribution is described later.

[0070] The optimal specific surface area, determined by the BET method from the CO2 adsorption isotherm at 25℃, is 350 m². 2 / g or more, preferably 400m 2 / g or more, further optimized 415m 2 / g or higher. If the specific surface area is within the above range, it tends to selectively adsorb oxygen and the like, which can further improve the performance for separating oxygen and the like. In addition, the specific method for determining the specific surface area by the BET method from the CO2 adsorption isotherm at 25°C can be found in the examples.

[0071] In this embodiment, the maximum center of the main peak of the preferred oxygen adsorption rate constant distribution of the carbon molecular sieve is 0.030 s⁻¹. 1 Above and 0.250 seconds - 1 The following, more preferably, is 0.110 seconds. 1 Above and 0.130 seconds - 1 The following indicates that the maximum center of the main peak of the oxygen adsorption rate constant distribution represents the adsorption rate of the carbon molecular sieve. By placing it within the aforementioned range, the adsorption rate of oxygen and other substances by the carbon molecular sieve is optimized, further improving its performance for separating oxygen and other substances compared to existing carbon molecular sieves. Furthermore, the maximum center of the main peak of the oxygen adsorption rate constant distribution is less than 0.030 s⁻¹. 1 In such cases, the adsorption of oxygen and other substances tends to become too slow, exceeding 0.250 seconds. 1 Under certain conditions, the adsorption of oxygen and other substances tends to become too rapid. Therefore, when using this type of carbon molecular sieve as an adsorbent in pressure swing adsorption (PSA) or temperature swing adsorption (TSA), it may be difficult to optimize the operating conditions of the gas separation device. Furthermore, the method for determining the maximum center of the main peak of the oxygen adsorption rate constant distribution is described later.

[0072] In the carbon molecular sieve of this embodiment, the volume of the pores with a pore inlet diameter of 0.37 nm or more and 0.46 nm or less (hereinafter also referred to as "pore volume with a specific pore inlet diameter"), determined by molecular probe microanalysis, is preferably 0.150 mL / g or more, more preferably 0.220 mL / g or more, and even more preferably 0.225 mL / g or more and 0.260 mL / g or less. The pore inlet diameter and the pore volume with that pore inlet diameter are also very important when separating oxygen from air, separating carbon dioxide from a mixture of carbon dioxide and methane, and separating chain olefins from a mixture of chain olefins and chain alkanes. According to the inventors' research, by setting the pore volume with the specific pore inlet diameter to 0.150 mL / g or more, the pore inlet diameter and the adsorption capacity for oxygen, etc., of the carbon molecular sieve are optimized, and compared with conventional carbon molecular sieves, the performance for separating oxygen, etc., is likely to be further improved. Furthermore, the upper limit can be, for example, below 0.300 mL / g. The method for determining the pore volume with a specific pore inlet diameter is described later.

[0073] The packing density (hereinafter also simply referred to as "packing density") of the carbon molecular sieve in this embodiment, as determined according to JIS K1474 (2014) 7.8, is preferably 0.660 g / mL or more and 0.730 g / mL or less, more preferably 0.670 g / mL or more and 0.725 g / mL or less, further preferably 0.675 g / mL or more and 0.720 g / mL or less, and even more preferably 0.680 g / mL or more and 0.715 g / mL or less. If the packing density is within the above range, it is more suitable to pack the carbon molecular sieve as an adsorbent in an apparatus utilizing pressure swing adsorption or temperature swing adsorption, thus tending to further selectively adsorb oxygen and the like, and further improving the performance for separating oxygen and the like. A specific method for determining the packing density can be found in the examples.

[0074] The compressive strength per unit area (hereinafter also simply referred to as "compressive strength") of the carbon molecular sieve in this embodiment is preferably 8.5 N / mm². 2 Above and 30.0 N / mm 2 The following, or more preferably, is 9.0 N / mm 2 Above and 28.0 N / mm 2 The following, and more preferably, is 9.5 N / mm. 2 Above and 26.0 N / mm 2 The following, and more preferably, is 10.0 N / mm 2 Above and 25.0 N / mm 2 The following applies. If the compressive strength is within the above-mentioned range, it is more suitable to incorporate carbon molecular sieves as adsorbents in devices utilizing pressure swing adsorption (PSA) or temperature swing adsorption (TSA). Therefore, it tends to selectively adsorb oxygen and the like, further improving its performance for separating oxygen and the like. Furthermore, when using carbon molecular sieves as adsorbent materials in devices utilizing PSA or TSA, it tends to further reduce wear on the adsorbent materials. Specific methods for measuring compressive strength can be found in the examples.

[0075] The carbon molecular sieve of this embodiment preferably contains non-graphitized carbon, and more preferably is composed of non-graphitized carbon. If the carbon molecular sieve is such carbon, it tends to selectively adsorb oxygen and the like, and its performance for separating oxygen and the like is further improved. Examples of non-graphitized carbon include: coal; coconut shells such as palm and coconut shells; natural fibers such as hemp and cotton; synthetic fibers such as rayon and polyester; synthetic resins such as polyacrylonitrile, phenolic resin, polyvinylidene chloride, polycarbonate and polyvinyl alcohol; carbon, carbon black, glassy carbon, etc., made from charcoal and the like.

[0076] (Method for determining the half-width and maximum center of the main peak of the oxygen adsorption rate constant distribution)

[0077] The half-width and maximum center of the main peak of the oxygen adsorption rate constant distribution are obtained as follows.

[0078] The oxygen adsorption rate constant distribution can be obtained from the adsorption rate curve obtained using a known constant-volume method, as follows. Figure 1 The schematic diagram of the oxygen adsorption device shown is used for illustration.

[0079] First, in the oxygen adsorption apparatus, valves 1, 2, and 3 are closed, and 3g of carbon molecular sieve 7 is filled into the 20mL sample cell 6. Then, valves 2 and 3 are opened, and a vacuum is drawn from the outlet 9 into the sample cell 6 and the 100mL gas storage section 5. Next, valves 2 and 3 are closed, and valve 1 is opened, introducing oxygen (purity: 99.999%, manufactured by Naniwa Sanso Corporation) into the gas storage section 5 through the inlet 8 until the pressure reaches approximately 75kPa (absolute pressure). Then, valve 1 is closed, and valve 2 is opened to begin the oxygen adsorption measurement. The pressure P within the system is measured using pressure sensor 4 over time t (seconds) from the point when the valves are opened. t The process continued until equilibrium was reached. Furthermore, the measurements were performed at 25°C (room temperature).

[0080] Here, the adsorption fraction θ(t) is defined by the following equation (1). By this definition, the adsorption rate curve θ can be obtained, where θ(t) = 0 when the gas is not adsorbed, the value of θ(t) increases as adsorption proceeds, and θ(t) = 1 at the point of equilibrium.

[0081] θ(t)=(P t -P0) / (P eq -P0)···(1)

[0082] In equation (1), P t P is the pressure (kPa) within the system after time t (seconds). eq The pressure (kPa) at the point of equilibrium is P0, which is the pressure (kPa) in the system at the instant valve 2 is opened, as defined by the following equation (2).

[0083] P0 = P g ×V g / V d ···(2)

[0084] In equation (2), P g V is the pressure (kPa) of the gas storage section 5 before valve 2 opens. g V is the volume (mL) of the gas storage section 5. d The dead volume of the system is the volume (mL) after deducting the volume occupied by carbon molecular sieve 7 from the total volume of the system.

[0085] If we plot the adsorption fraction θ(t) on the vertical axis and the elapsed time t (seconds) on the horizontal axis, we get the following: Figure 2 The example shows the oxygen adsorption rate curve.

[0086] Next, the following steps are performed to obtain the adsorption rate constant distribution from the oxygen adsorption rate curve.

[0087] Because carbon molecular sieves possess a wide pore diameter distribution ranging from macropores to ultramicropores, their adsorption rate constants also exhibit a distribution. Therefore, a cluster of theoretical adsorption rate curves, theoretically derived from multiple adsorption rate constants, is prepared, and the experimentally obtained adsorption rate curves are reproduced by linearly adding them. The distribution of the adsorption rate constants can be represented by the weighting coefficients applied to each theoretical adsorption rate curve during linear addition. Specifically, this is performed as follows.

[0088] First, prepare a set of theoretical adsorption rate curves for oxygen. Theoretical adsorption rate curve θ ideal According to the LDF model, it is expressed by the following equation (3). Furthermore, in the theoretical adsorption rate curve θ... ideal In this context, the theoretical adsorption fraction at a certain time t will be expressed as θ. ideal (t). For the LDF model, please refer to Adsorption (2017) 23:131-147.

[0089] θideal(t)=1-exp(-α×k LDF ×t)···(3)

[0090] In equation (3), α is the value defined in equation (4) below. Additionally, k LDF The adsorption rate constant (seconds) 1 ), t represents time (seconds).

[0091] α=P0 / P eq ···(4)

[0092] In equation (4), P0 and P eq Same as above. That is, P0 is the pressure (kPa) defined in equation (2) above, P eq The pressure (kPa) at the point in time to reach equilibrium.

[0093] To obtain the theoretical adsorption rate curve cluster of oxygen, as k LDF Using the following values, prepare a set consisting of a total of 46 theoretical adsorption rate curves.

[0094] 1.00×10 -9 1.58×10 -9 2.51×10 -9 3.98×10 -9 6.31×10-9 1.00×10 -8 1.58×10 -8 2.51×10 -8 3.98×10 -8 6.31×10 -8 1.00×10 -7 1.58×10 -7 2.51×10 -7 3.98×10 -7 6.31×10 -7 1.00×10 -6 1.58×10 -6 2.51×10 -6 3.98×10 -6 6.31×10 -6 1.00×10 -5 1.58×10 -5 2.51×10 -5 3.98×10 -5 6.31×10 -5 1.00×10 -4 1.58×10 -4 2.51×10 -4 3.98×10 -4 6.31×10 -4 1.00×10 -3 1.58×10 -3 2.51×10 -3 3.98×10 -3 6.31×10 -2 1.58×10 -2 2.51×10 -2 3.98×10 -2 6.31×10 -2 1.00×10 -1 1.58×10 -1 2.51×10 -1 3.98×10 -1 6.31×10 -1 And 1.00.

[0095] To obtain the theoretical oxygen adsorption rate curve cluster, the following values ​​are used as t.

[0096] 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 400, 500, 600, 700, 800, 900, 1000, 1500, 2000, and 2400.

[0097] The theoretical oxygen adsorption rate curves obtained from this are clustered in Figure 3 As shown.

[0098] Next, regarding the passage Figure 3 The method of reproducing the oxygen adsorption rate curve obtained from the experiment by linearly adding the theoretical adsorption rate curve cluster shown is explained.

[0099] First, Figure 3 The theoretical adsorption rate curve cluster shown is represented by a square matrix A. That is, let Aij represent the i-th row and j-th column of A, such as in A... 11 List k LDF =1.0×10 -9 The value of t = 0.5, in A 12 List k LDF =1.0×10 -9 The value of k is listed in the first column of A for each t, ​​just like the value of t=1. LDF =1.0×10 -9 The value of θ at that time.

[0100] Next, as before, list k for each t in column 2 of A. LDF =1.58×10 -9 The value of θ at time k. LDF Repeat this operation to obtain a 46th power square matrix A.

[0101] Next, we use vector b to represent the oxygen adsorption rate curve obtained from the experiment.

[0102] That is, the theoretical adsorption fraction θ at t = 0.5, 1, 1.5, 2, 2.5, 3, 3.5, 4, 4.5, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 20, 25, 30, 35, 40, 45, 50, 60, 70, 80, 90, 100, 150, 200, 250, 300, 400, 500, 600, 700, 800, 900, 1000, 1500, 2000, and 2400 is determined from the oxygen adsorption rate curves obtained in the experiment. ideal (t), listed as vector b.

[0103] Next, we use a vector x to represent the weights applied to each theoretical adsorption rate curve for linear addition. Here, Tikhonov regularization is used to find the optimal vector x.

[0104] That is, find the x that minimizes the value expressed by the following equation (5).

[0105] ||Ax-b|| 2 +λ||x|| 2 ···(5)

[0106] In equation (5), ||Ax-b|| 2 =Σ i (Σ j A ij x j -b i ) 2 ,||x|| 2 =Σ i x j 2 λ is the regularization parameter.

[0107] As a candidate for λ, the following preparations are made.

[0108] 0, 0.01, 0.0398, 0.063, 0.1, 0.398, 0.63, 1, 3.98, 6.3, 10, 15.8, 25.1, 39.8, 63, 100, 158, 251, 398, 630, 1000, 1580, 2510, 3980, 6300 and 10000.

[0109] For each λ, find the x that minimizes the value expressed by equation (5). At this point, use the solver function of Microsoft Excel 2016 to find x. The solver's solution method is set to GRG (Generalized Reduced Gradient) nonlinearity (Generalized Reduced Gradient). From the x corresponding to each λ obtained in this way, determine the optimal λ and its corresponding x. The L-curve method is used here. That is, using log... 10 ||x|| is the horizontal axis, and ||x|| is the logarithm. 10 Plot the L-curve using ||Ax-b|| on the vertical axis, employing λ and x corresponding to the inflection point of the L-shape. Figure 4 Examples of the L-curve method and the points to be used. Furthermore, Figure 4 The arrows in the diagram represent the optimal λ and its corresponding x.

[0110] Through the above steps, the weight x applied to each theoretical adsorption rate curve is obtained. Then, the horizontal axis represents the adsorption rate constant (k) of the theoretical adsorption rate curve.LDF) The vertical axis represents the weight (x) corresponding to each adsorption rate constant, and a plot is created. This yields the adsorption rate constant distribution. In this specification, this plot is defined as the adsorption rate constant distribution. Figure 5 The example shows the adsorption rate constant distribution obtained using this method. Figure 5 From this, we can know that in k LDF =0.1 (seconds - 1 The area near the main peak, i.e., the maximum value of the weight, reaches its maximum.

[0111] The half-width and maximum center of the main peak of the oxygen adsorption rate constant involved in this embodiment can be fitted using a log-normal distribution function. Figure 5 The adsorption rate constant is obtained from the distribution shown. The fitting was performed using OriginPro2021b manufactured by OriginLab, which utilizes the peak fitting function.

[0112] (Method for determining the volume of a fine pore with a specific inlet diameter)

[0113] First, in this specification, the molecular probe method refers to determining the volume of a pore with an inlet diameter greater than or equal to that minimum molecular diameter by adsorbing gas molecules of known minimum molecular diameter and density onto a carbon molecular sieve and measuring the amount of adsorption.

[0114] The volume of a pore with an inlet diameter greater than 0.37 nm and less than 0.46 nm, determined by the molecular probe method, can be calculated as follows: Using... Figure 6 The schematic diagram of the apparatus for measuring pore volume using the molecular probe method is shown for illustration.

[0115] like Figure 6 As shown, a petri dish 24 filled with carbon disulfide (minimum molecular diameter: 0.37 nm, density: 1.263 g / mL) is placed in a glass container 20 with holes 21. A weighing bottle 22 containing carbon molecular sieves as samples is placed on top of the petri dish via a perforated plate 23. The glass container 20 is placed in a constant temperature bath at 25°C to allow carbon disulfide to adsorb onto the carbon molecular sieves for 24 hours. The equilibrium adsorption capacity Ag / g of carbon disulfide per 1g of carbon molecular sieve is determined from the mass change of the carbon molecular sieve before and after adsorption. Since the minimum molecular diameter of carbon disulfide is 0.37 nm and the density of carbon disulfide is 1.263 g / mL, the volume A'mL / g of the pores with an inlet diameter of 0.37 nm or larger is calculated using A' = A / 1.263.

[0116] Replace carbon disulfide with chloroform (minimum molecular diameter: 0.46 nm, density: 1.410 g / mL), and perform the same steps as above to determine the equilibrium adsorption capacity of chloroform per 1 g of carbon molecular sieve, B g / g. Then, calculate the volume of the pores with an inlet diameter of 0.46 nm or more, B' mL / g, using B' = B / 1.410.

[0117] Using the calculated values ​​of A' and B', the pore volume with a specific pore inlet diameter can be determined by A'-B' mL / g.

[0118] (The shape of the carbon molecular sieve)

[0119] There are no particular limitations on the shape of carbon molecular sieves; any shape suitable for known adsorbent materials can be used. Examples of such shapes include: granular, powdery, substrate-like (flake-like), rod-shaped, block-shaped, spherical, ellipsoidal, twisted, and fibrous. Granular or powdery shapes are preferred for carbon molecular sieves. Because of the aforementioned shape, carbon molecular sieves can selectively adsorb oxygen and the like, further improving their performance in separating oxygen and the like. Therefore, carbon molecular sieves are easily adaptable to various applications. Furthermore, when carbon molecular sieves are granular, unwanted micropowder is less likely to be generated, thus reducing the likelihood of pipe blockage during the molding process. From the perspective of ease of molding, cylindrical granular shapes (hereinafter also simply referred to as "cylindrical granules") are more preferable for carbon molecular sieves.

[0120] When the carbon molecular sieve is in granular form, its top-view shape can be any shape suitable for known adsorbent materials. Examples of such shapes include circular, elliptical, rectangular, rod-shaped, and twisted shapes when viewed from above. The thickness of the carbon molecular sieve is not particularly limited when it is granular, and can be referenced from known adsorbent materials. As for the thickness, it is preferably suitable for use as an adsorbent in pressure swing adsorption or temperature swing adsorption methods, typically between 100 μm and 10,000 μm.

[0121] When the carbon molecular sieve is in the form of cylindrical particles, it is preferable that the particle diameter is 0.1 mm or more and 4.0 mm or less, and the aspect ratio is 1:1 to 1:10. Such particles are suitable as adsorbent materials in pressure swing adsorption or temperature swing adsorption.

[0122] Furthermore, in this specification, the particle diameter refers to the average diameter of 30 randomly collected granular carbon molecular sieves. The diameter can be measured using, for example, calipers. For specific measurement methods, please refer to the examples.

[0123] In this specification, the aspect ratio refers to the ratio of the diameter to the height of a carbon molecular sieve, i.e., the diameter of the carbon molecular sieve : its height. The aspect ratio is calculated by taking the average of the aspect ratios of 30 randomly collected carbon molecular sieves. For specific measurement methods, please refer to the examples.

[0124] When the carbon molecular sieve is in powder form, the particle size (average particle size, D50) is preferably 1 μm or more and 150 μm or less. This powder is suitable as an adsorbent in temperature-switched adsorption methods.

[0125] Furthermore, in this specification, the average particle size (D50) is determined using a laser diffraction light scattering particle size distribution measuring device as the median diameter of the volume standard.

[0126] (use)

[0127] The carbon molecular sieve of this embodiment is suitable for use with air as the target gas for separation. That is, when the target gas for separation is air, the carbon molecular sieve can selectively adsorb oxygen from the air.

[0128] The carbon molecular sieve of this embodiment can be used to separate a mixture of gases containing at least two gases selected from the group consisting of carbon dioxide, methane, ethane, ethylene, propylene, and propane. The target gas is a mixture of gases containing at least two gases selected from the group consisting of carbon dioxide, methane, ethane, ethylene, propylene, and propane, and the carbon molecular sieve can selectively adsorb one or more gases from the mixture.

[0129] The carbon molecular sieve of this embodiment is suitable for use as a separation target gas in a mixture of carbon dioxide and methane. That is, when the separation target gas is a mixture of carbon dioxide and methane, the carbon molecular sieve can selectively adsorb carbon dioxide from the mixture.

[0130] The carbon molecular sieve of this embodiment is suitable for use as a separation target gas containing chain olefins and chain alkanes. That is, when the separation target gas is a mixture of chain olefins and chain alkanes, the carbon molecular sieve can selectively adsorb chain olefins from the mixture.

[0131] The carbon molecular sieve of this embodiment is suitable for use as a gas mixture containing propylene and propane as the target gas for separation. That is, when the target gas is a gas mixture containing propylene and propane, the carbon molecular sieve can selectively adsorb propylene from the gas mixture.

[0132] [Manufacturing method of carbon molecular sieve]

[0133] The carbon molecular sieve of this embodiment can be obtained by known manufacturing methods.

[0134] Examples of such methods include thermal decomposition, activation, coating, and vapor deposition. Thermal decomposition, coating, and vapor deposition are preferred manufacturing methods. By employing these methods, it is easier to manufacture oxygen adsorption rate constants with a half-width of 0.35 s⁻¹. 1 The specific surface area, calculated using the BET method from the CO2 adsorption isotherm at 25℃, is 300 m². 2 / g or more and 600m 2 Carbon molecular sieves with a density of less than / g. Next, the manufacturing method of using carbon molecular sieves as activated carbon will be described in detail as an example.

[0135] The manufacturing method of carbon molecular sieves includes: a carbonization process of carbonizing raw materials to obtain carbides; an activation process of activating carbides to obtain activated materials; and a calcination process of calcining activated materials.

[0136] (Carbonization process)

[0137] The manufacturing method of carbon molecular sieves includes a carbonization process of carbonizing raw materials to obtain carbides.

[0138] As a raw material, any material that can produce the desired carbon molecular sieve is acceptable; there are no particular limitations. The ideal is that the raw material becomes a difficult-to-graphitize carbon after carbonization.

[0139] Examples of such raw materials include: coal; coconut shells such as palm shells and coconut shells; natural fibers such as hemp and cotton; synthetic fibers such as rayon and polyester; synthetic resins such as polyacrylonitrile, phenolic resin, polyvinylidene chloride, polycarbonate and polyvinyl alcohol; and carbon, carbon black and glassy carbon made from charcoal and other similar materials.

[0140] The half-width of the main peak in the adsorption rate constant distribution, which tends to produce oxygen more easily, is 0.35 s⁻¹. 1 The specific surface area of ​​300 m² was obtained from the CO₂ adsorption isotherm at 25 °C using the BET method. 2 / g or more and 600m 2 From the perspective of carbon molecular sieves of less than / g, as raw materials, it is preferable to include at least one of the following: coal, coconut shell, synthetic resin, phenolic resin and charcoal, and more preferably, at least one of the following: coconut shell and phenolic resin.

[0141] Additives may be included in the raw materials as needed. Additionally, additives may be added to the carbides as needed.

[0142] Examples of such additives include: water, coal tar, anhydrous tar, hard pitch, coal tar-based pitch, and petroleum-based pitch. One type of additive may be used alone, or two or more may be used in combination.

[0143] Additives, etc., are typically blended in quantities of 1 to 50 parts by mass relative to 100 parts by mass of raw materials or carbides. Furthermore, the total amount of additives, etc., is typically 1 to 100 parts by mass relative to 100 parts by mass of raw materials or carbides. When mixing raw materials or carbides and additives, the oxygen content in the raw materials or carbides can be adjusted in advance, within a range of 1% to 20% by mass relative to 100% by mass of the raw materials or carbides, as needed. Oxygen content adjustment can be achieved, for example, by mixing the raw materials or carbides and oxygen under heating conditions of 150°C to 300°C.

[0144] In the manufacturing method of carbon molecular sieves, the raw materials can be pulverized or shaped before carbonization. Examples of such methods include pulverizing the raw materials into powder using a known pulverizer before carbonization. Alternatively, methods can include shaping the raw materials into granules using known methods before carbonization.

[0145] When the raw material is made into a powder, the particle size (average particle size, D50) of the powder is preferably 1 μm or more and 150 μm or less.

[0146] There are no particular limitations on the carbonization method of the raw materials. For example, the method of heating to above 300°C and below 900°C under anaerobic conditions, preferably above 300°C and below 800°C, can be listed.

[0147] The carbonization time can be appropriately set according to the raw materials and the equipment used for carbonization. For example, a carbonization time of 15 minutes to 20 hours, preferably 30 minutes to 10 hours, is suitable. The carbonization process can be performed using known manufacturing equipment such as a rotary kiln. Furthermore, the carbonization process can be carried out under reduced pressure with air removed, or under a nitrogen atmosphere.

[0148] The half-width of the main peak in the adsorption rate constant distribution, which tends to produce oxygen more easily, is 0.35 s⁻¹. 1 The specific surface area, calculated using the BET method from the CO2 adsorption isotherm at 25℃, is 300 m². 2 / g or more and 600m 2 Considering carbon molecular sieves with a particle size below / g, in the manufacturing method of carbon molecular sieves, a known pulverizer can be used to pulverize the carbides into powder. In the manufacturing method of carbon molecular sieves, after the carbides are pulverized into powder, additives are added to the powdered carbides as needed, and the mixture is then kneaded using known methods. The resulting mixture is then shaped using known methods.

[0149] When the carbide is made into a powder, the particle size (average particle size, D50) of the carbide is preferably 1 μm or more and 150 μm or less.

[0150] The half-width of the main peak in the adsorption rate constant distribution, which tends to produce oxygen more easily, is 0.35 s⁻¹. 1 The specific surface area of ​​300 m² was obtained from the CO₂ adsorption isotherm at 25 °C using the BET method. 2 / g or more and 600m 2 From the perspective of carbon molecular sieves below / g, in the manufacturing method of carbon molecular sieves, known methods can be used to shape carbides, powdered carbides, mixtures or powdered mixtures into cylindrical particles.

[0151] When the carbide is shaped into cylindrical particles, the diameter of the cylindrical particles is generally preferably 0.1 mm or more and 4.0 mm or less. In addition, the aspect ratio (diameter:height) of the cylindrical particles is generally preferably 1:1 to 1:10.

[0152] The carbonization process described above yields carbides from the raw material. After carbonization, the carbides can be washed and / or dried. These conditions are not particularly limited and any known conditions can be used.

[0153] (Activation process)

[0154] The manufacturing method of carbon molecular sieves includes an activation process of activating carbides to obtain activated materials.

[0155] As an activation treatment, known methods can be employed. Examples of such methods include activation methods using active gases such as steam, oxygen, and carbon dioxide. Activation treatment can be performed using known manufacturing equipment such as rotary kilns and flow furnaces. Alternatively, activation treatment can be carried out under reduced pressure with air removed, or under a nitrogen atmosphere. As an activation treatment, for example, when using steam, the following method can be employed: contacting the carbide with steam at a flow rate of 10 liters (L) or more and 300 liters (L) or less per minute for 1 minute or more and 1440 minutes or less.

[0156] There is no particular limitation on the activation temperature, and the half-width of the main peak of the adsorption rate constant distribution, which tends to more easily produce oxygen, is 0.35 s⁻¹. 1 The specific surface area, calculated using the BET method from the CO2 adsorption isotherm at 25℃, is 300 m². 2 / g or more and 600m 2 Considering the angle of carbon molecular sieves with a temperature of less than / g, it is preferably above 750°C and below 1200°C, more preferably above 800°C and below 1100°C.

[0157] The partial pressure of the active gas is, for example, 10% or more and 100% or less, preferably 30% or more and 100% or less.

[0158] The activation time can be appropriately set according to conditions such as raw materials, activation temperature, and manufacturing equipment. For example, the activation time is 30 minutes or more and 48 hours or less, preferably 1.0 hour or more and 36 hours or less, and more preferably 70 minutes or more and 24 hours or less.

[0159] After activation, washing and / or drying processes can be performed. There are no particular limitations on these conditions; known conditions can be used.

[0160] (Firing process)

[0161] The manufacturing method of carbon molecular sieves includes: the calcination process of calcining activated materials.

[0162] By performing a sintering process, the pore diameter distribution of the activated material is adjusted, resulting in a more uniform pore diameter distribution in the carbon molecular sieve. Therefore, compared to existing carbon molecular sieves, carbon molecular sieves selectively adsorb oxygen and other substances, thus improving their performance in separating oxygen and other similar materials.

[0163] Examples of firing processes include: methods that bring a carbon source into contact with an activator for firing. Examples of firing methods include: thermal decomposition, coating, and vapor deposition.

[0164] Examples of carbon sources used in coating or vapor deposition methods include: coal tar, anhydrous coal tar, coal tar-based pitch, petroleum-based pitch, and creosote. Examples of carbon sources used in thermal decomposition and vapor deposition methods include: alcohols such as methanol and ethanol; esters such as ethyl acetate; ketones such as acetone and methyl ethyl ketone; aromatic hydrocarbons such as benzene, toluene, and xylene; aliphatic hydrocarbons such as hexane; amides such as dimethylformamide; and polyols such as ethylene glycol.

[0165] From the perspective of making it easier to adjust the pore diameter distribution of the activator and to make the pore diameter distribution of the carbon molecular sieve more uniform, in the coating or vapor deposition method, when the carbon source is benzene and the firing temperature is 600°C or higher and 900°C or lower, the lower limit of the amount of benzene used relative to 100 parts by mass of the activator is generally 1.0 parts by mass or more, preferably 1.5 parts by mass or more, more preferably 2.0 parts by mass or more, further preferably 2.5 parts by mass or more, and even more preferably 3.0 parts by mass or more. The upper limit of the amount of benzene used relative to 100 parts by mass of the activator is generally 10 parts by mass or less, preferably 9.0 parts by mass or less, more preferably 8.5 parts by mass or less, further preferably 8.0 parts by mass or less, and even more preferably 7.5 parts by mass or less.

[0166] From the perspective of making it easier to adjust the pore diameter distribution of the activator and to make the pore diameter distribution of the carbon molecular sieve more uniform, the firing temperature is usually above 600°C and below 900°C, more preferably above 700°C and below 800°C.

[0167] The firing time can be set appropriately according to the firing temperature, for example, more than 15 minutes and less than 240 minutes.

[0168] The firing process can be carried out, for example, under a nitrogen atmosphere, an argon atmosphere, or other inert gas atmosphere.

[0169] These gases can be used as carrier gases, and the calcination process can be performed while the carbon source is flowing through them. In this case, the carrier gas flow rate is preferably 110 L / min or more, more preferably 150 L / min or more and 300 L / min or less, and even more preferably 170 L / min or more and 250 L / min or less. Benzene is preferred as the carbon source flowing through the carrier gas. According to this calcination process, it is easier to produce an oxygen adsorption rate constant distribution with a half-width of 0.35 s⁻¹. 1 The specific surface area, calculated using the BET method from the CO2 adsorption isotherm at 25℃, is 300 m². 2 / g or more and 600m 2 Carbon molecular sieves with a density of less than / g.

[0170] After firing, washing and / or drying processes can be performed. There are no particular limitations on these conditions; known conditions can be used.

[0171] When the carbon molecular sieve after calcination is in powder form, the particle size (average particle size, D50) of the powder is preferably 1 μm or more and 150 μm or less.

[0172] When the calcined carbon molecular sieve is in the form of cylindrical particles, its diameter is generally preferably 0.1 mm or more and 4.0 mm or less. In addition, its aspect ratio (diameter:height) is generally preferably 1:1 to 1:10.

[0173] [Gas Separation Device]

[0174] The gas separation device is not particularly limited as long as it possesses the aforementioned carbon molecular sieve and can separate oxygen using pressure swing adsorption or temperature swing adsorption. In other words, the gas separation device is a device that effectively separates and recovers gases other than oxygen from oxygen-containing air. In addition to possessing the aforementioned carbon molecular sieve, such a gas separation device may also have the same configuration as existing gas separation devices.

[0175] The gas separation device may include the aforementioned carbon molecular sieve, and selectively adsorb carbon dioxide from a mixed gas containing carbon dioxide and methane using pressure swing adsorption or temperature swing adsorption, effectively separating and recovering methane gas. In addition to the aforementioned carbon molecular sieve, this gas separation device may also have the same configuration as existing gas separation devices.

[0176] The gas separation device may include the aforementioned carbon molecular sieve, and utilize pressure swing adsorption (PSA) or temperature swing adsorption (TSA) to selectively adsorb chain olefins from a mixture of gases containing chain olefins and chain alkanes, effectively separating and recovering the chain olefin gas. In addition to the aforementioned carbon molecular sieve, this gas separation device may also have the same configuration as existing gas separation devices.

[0177] The gas separation device may include the aforementioned carbon molecular sieve, and selectively adsorb propylene from a mixed gas containing propylene and propane using pressure swing adsorption or temperature swing adsorption, effectively separating and recovering propylene gas. In addition to the aforementioned carbon molecular sieve, this gas separation device may also have the same configuration as existing gas separation devices.

[0178] Specifically, examples include the gas separation devices described below.

[0179] The gas separation device of this embodiment is a gas separation device for separating oxygen from air by pressure swing adsorption, and it has a carbon molecular sieve as the adsorbent in the pressure swing adsorption method.

[0180] The gas separation device of this embodiment is a gas separation device for separating carbon dioxide from a mixed gas containing carbon dioxide and methane by pressure swing adsorption, and includes a carbon molecular sieve as the adsorbent in the pressure swing adsorption method.

[0181] The gas separation apparatus of this embodiment is a gas separation apparatus for separating chain olefins from a mixed gas containing chain olefins and chain alkanes by pressure swing adsorption, and includes a carbon molecular sieve as the adsorbent in the pressure swing adsorption method.

[0182] The gas separation device of this embodiment is a gas separation device for separating and adsorbing propylene from a mixed gas containing propylene and propane by pressure swing adsorption, and includes a carbon molecular sieve as the adsorbent in the pressure swing adsorption method.

[0183] The gas separation device of this embodiment is a gas separation device for separating oxygen from air by temperature-switching adsorption, and it has a carbon molecular sieve as the adsorbent in the temperature-switching adsorption method.

[0184] The gas separation device of this embodiment is a gas separation device for separating carbon dioxide from a mixed gas containing carbon dioxide and methane by temperature swing adsorption, and includes a carbon molecular sieve as an adsorbent in the temperature swing adsorption method.

[0185] The gas separation device of this embodiment is a gas separation device for separating chain olefins from a mixed gas containing chain olefins and chain alkanes by means of temperature-switching adsorption, and includes a carbon molecular sieve as an adsorbent in the temperature-switching adsorption method.

[0186] The gas separation device of this embodiment is a gas separation device for separating propylene from a mixed gas containing propylene and propane by a temperature-switching adsorption method, and includes a carbon molecular sieve as the adsorbent in the temperature-switching adsorption method.

[0187] Carbon molecular sieves are suitable for use as adsorbent materials. Adsorbent materials can be formed solely from carbon molecular sieves, or they can be combined with other known components.

[0188] Adsorbent materials can efficiently separate oxygen from the air, making them suitable for gas separation devices that employ pressure swing adsorption or temperature swing adsorption.

[0189] Next, using Figure 7 An example of a gas separation device is described, which is used to separate oxygen from air and has a carbon molecular sieve as an adsorbent in the pressure swing adsorption method.

[0190] like Figure 7 As shown, the gas separation device consists of adsorption towers A and B filled with carbon molecular sieves, a compressor 11 for pressurizing the raw material air, a raw material tank 12 for storing the raw material air, a product tank 17 for storing the product gas, valves 13a, 13b, 14a and 14b for switching the process of adsorption towers A and B, valves 16a and 16b for conveying the product gas generated by the adsorption towers to the product tank, a pressure equalization valve 15, a valve 18 for removing the product gas, and an outlet 19 for discharging the adsorbed gas.

[0191] The adsorbent material can efficiently separate carbon dioxide from a mixture of gases containing carbon dioxide and methane, and is therefore suitable for gas separation devices using pressure swing adsorption or temperature swing adsorption.

[0192] Next, using Figure 8 An example of a gas separation device is described, which is used to separate carbon dioxide from a mixture of carbon dioxide and methane, and has a carbon molecular sieve as an adsorbent in the pressure swing adsorption method.

[0193] like Figure 8As shown, the gas separation device consists of adsorption towers C and D filled with carbon molecular sieves, a raw material gas tank 25, a product tank 30 for storing product gas, valves 26a, 26b, 27a and 27b for switching the process of adsorption towers C and D, valves 29a and 29b for conveying the product gas generated by the adsorption towers to the product tank, a pressure equalization valve 28, a valve 31 for removing the product gas, and a vacuum pump 32 for discharging the adsorbed gas.

[0194] The adsorbent material can efficiently separate chain olefins from a mixture of gases containing chain olefins and chain alkanes, and is therefore suitable for gas separation devices employing pressure swing adsorption or temperature swing adsorption.

[0195] The adsorbent material can efficiently separate propylene from a mixed gas containing propylene and propane, and is therefore suitable for gas separation devices using pressure swing adsorption or temperature swing adsorption.

[0196] Next, using Figure 9 An example of a gas separation device is described, which is used to separate chain olefins from a mixture of gases containing chain olefins and chain alkanes, and has a carbon molecular sieve as an adsorbent in the pressure swing adsorption method.

[0197] like Figure 9 As shown, the gas separation device consists of adsorption towers E and F filled with carbon molecular sieves, a raw material gas tank 33, a product tank 40 for storing product gas, valves 34a, 34b, 37a and 37b for switching the process of adsorption towers E and F, a vacuum pump 39 for discharging the adsorbed gas as product gas and conveying it to the product tank 40, valves 35a and 35b for conveying the adsorbed gas as product gas to the vacuum pump, a pressure equalization valve 36, a valve 41 for taking out product gas, and a valve 38 for discharging permeated gas.

[0198] Example

[0199] The present invention is illustrated below with examples and comparative examples, but the invention is not limited to these examples.

[0200] [Example 1]

[0201] (Carbonization process)

[0202] The phenolic resin was carbonized in a rotary kiln by removing air and simultaneously heating for approximately 5 hours until a final temperature of 800°C was reached. 100 parts by weight of the phenolic resin carbide was pulverized until the average particle size (D50) was below 0.15 mm, yielding a powdered phenolic resin carbide. 20 parts by weight of water and 40 parts by weight of coal tar were added to 100 parts by weight of this phenolic resin carbide powder and then mixed. The resulting mixture was fed into an extruder to form cylindrical granules with a diameter of 2.0 mm and an aspect ratio of 1:5. Thirty cylindrical granules were randomly sampled, and their diameters were measured using calipers. The average diameter was calculated. Additionally, 30 cylindrical granules were randomly sampled, and their heights were measured using calipers. The average height was calculated, and the aspect ratio was determined as the average diameter:height. As a result, the diameter of the obtained cylindrical particles was confirmed to be 2.0 mm and the aspect ratio was 1:5.

[0203] (Activation process)

[0204] The resulting cylindrical particles were purged of air in a rotary kiln while being heated for approximately 5 hours until the final temperature reached 800°C. Then, water vapor was introduced into contact with the cylindrical particles at a flow rate of 100 liters per minute for 100 minutes to perform activation treatment, yielding the activated product.

[0205] (Firing process)

[0206] Next, under a nitrogen atmosphere at 800°C, 5.0 parts by mass of benzene were passed through at a nitrogen flow rate of 200 L / min for 120 minutes, relative to 100 parts by mass of the obtained activator. This calcination process yielded cylindrical granular carbon molecular sieves. Thirty randomly sampled cylindrical granular carbon molecular sieves were used to measure their diameters using calipers, and the average diameter was calculated. Additionally, another 30 randomly sampled carbon molecular sieves were used to measure their heights using calipers, and the average height was calculated. The aspect ratio was then determined as the average diameter:height. The results confirmed that the obtained carbon molecular sieve particles had a diameter of 2.0 mm and an aspect ratio of 1:5.

[0207] [Example 2]

[0208] Except for changing the amount of benzene from 5.0 parts by mass to 7.5 parts by mass in the firing process, cylindrical granular carbon molecular sieves were obtained using the same method as in Example 1. Following the same procedure as in Example 1, when determining the particle diameter and aspect ratio, it was confirmed that the diameter of the obtained cylindrical granular carbon molecular sieve particles was 2.0 mm and the aspect ratio was 1:5.

[0209] [Example 3]

[0210] (Carbonization process)

[0211] The coconut shells were carbonized by removing air from a rotary kiln and heating for approximately 5 hours until a final temperature of 800°C was reached. 100 parts by weight of the coconut shell carbonized material were pulverized using a pulverizer until the average particle size (D50) was below 0.1 mm, yielding a coconut shell carbonized powder. 20 parts by weight of water and 40 parts by weight of coal tar were added to 100 parts by weight of this coconut shell carbonized powder and mixed. The resulting mixture was fed into an extruder to form cylindrical granules with a diameter of 2.0 mm and an aspect ratio of 1:5. Following the same procedure as in Example 1, the diameter and aspect ratio of the granules were determined, confirming that the obtained cylindrical granules had a diameter of 2.0 mm and an aspect ratio of 1:5.

[0212] (Activation process)

[0213] The resulting cylindrical particles were purged of air in a rotary kiln while being heated for approximately 5 hours until the final temperature reached 800°C. Then, water vapor was introduced into contact with the cylindrical particles at a flow rate of 100 liters per minute for 100 minutes to perform activation treatment, yielding the activated product.

[0214] (Firing process)

[0215] Next, under a nitrogen atmosphere at 800°C, 7.5 parts by mass of benzene were passed through for 120 minutes at a nitrogen flow rate of 200 L / min relative to 100 parts by mass of the obtained activator. This calcination process yielded cylindrical granular carbon molecular sieves. Following the same procedure as in Example 1, the diameter and aspect ratio of the cylindrical granular carbon molecular sieves were determined, confirming a diameter of 2.0 mm and an aspect ratio of 1:5.

[0216] [Example 4]

[0217] Except for changing the benzene content from 7.5 parts by mass to 7.0 parts by mass during the firing process, carbon molecular sieves were obtained using the same method as in Example 3. Following the same procedure as in Example 1, the diameter and aspect ratio of the cylindrical particles were determined, confirming a diameter of 2.0 mm and an aspect ratio of 1:5. Furthermore, following the same procedure as in Example 1, the diameter and aspect ratio of the cylindrical granular carbon molecular sieves were determined, confirming a diameter of 2.0 mm and an aspect ratio of 1:5.

[0218] [Example 5]

[0219] Except for changing the activation time for adhering water vapor to the cylindrical particles from 100 minutes to 120 minutes in the activation process and changing the benzene content from 7.5 parts by mass to 6.0 parts by mass in the firing process, carbon molecular sieves were obtained using the same method as in Example 3. Following the same procedure as in Example 1, when determining the diameter and aspect ratio of the cylindrical particles, it was confirmed that the diameter of the cylindrical particles was 2.0 mm and the aspect ratio was 1:5. Furthermore, following the same procedure as in Example 1, when determining the diameter and aspect ratio of the cylindrical granular carbon molecular sieve, it was confirmed that the diameter of the carbon molecular sieve was 2.0 mm and the aspect ratio was 1:5.

[0220] [Example 6]

[0221] Except for changing the benzene content from 7.5 parts by mass to 5.0 parts by mass in the firing process, carbon molecular sieves were obtained using the same method as in Example 3. Following the same procedure as in Example 1, when determining the diameter and aspect ratio of the cylindrical particles, it was confirmed that the diameter of the cylindrical particles was 2.0 mm and the aspect ratio was 1:5. Furthermore, following the same procedure as in Example 1, when determining the diameter and aspect ratio of the cylindrical granular carbon molecular sieves, it was confirmed that the diameter of the carbon molecular sieves was 2.0 mm and the aspect ratio was 1:5.

[0222] [Example 7]

[0223] Except for changing the benzene content from 7.5 parts by mass to 4.0 parts by mass in the firing process, carbon molecular sieves were obtained using the same method as in Example 3. Following the same procedure as in Example 1, when determining the diameter and aspect ratio of the cylindrical particles, it was confirmed that the diameter of the cylindrical particles was 2.0 mm and the aspect ratio was 1:5. Furthermore, following the same procedure as in Example 1, when determining the diameter and aspect ratio of the cylindrical granular carbon molecular sieves, it was confirmed that the diameter of the carbon molecular sieves was 2.0 mm and the aspect ratio was 1:5.

[0224] [Example 8]

[0225] Except for changing the activation time for adhering water vapor to the cylindrical particles from 100 minutes to 80 minutes in the activation process and changing the benzene content from 7.5 parts by mass to 3.0 parts by mass in the firing process, carbon molecular sieves were obtained using the same method as in Example 3. Following the same procedure as in Example 1, when determining the diameter and aspect ratio of the cylindrical particles, it was confirmed that the diameter of the cylindrical particles was 2.0 mm and the aspect ratio was 1:5. Furthermore, following the same procedure as in Example 1, when determining the diameter and aspect ratio of the cylindrical granular carbon molecular sieve, it was confirmed that the diameter of the carbon molecular sieve was 2.0 mm and the aspect ratio was 1:5.

[0226] [Comparative Example 1]

[0227] Except for changing the carrier gas flow rate from 200 L / min to 100 L / min during the firing process, carbon molecular sieves were obtained using the same method as in Example 1. Following the same procedure as in Example 1, when determining the diameter and aspect ratio of the cylindrical particles, it was confirmed that the diameter of the cylindrical particles was 2.0 mm and the aspect ratio was 1:5. Furthermore, following the same procedure as in Example 1, when determining the diameter and aspect ratio of the cylindrical granular carbon molecular sieves, it was confirmed that the diameter of the carbon molecular sieves was 2.0 mm and the aspect ratio was 1:5.

[0228] [Comparative Example 2]

[0229] Except for changing the activation time for adhering water vapor to the cylindrical particles from 100 minutes to 60 minutes in the activation process and changing the benzene content from 7.5 parts by mass to 3.0 parts by mass in the firing process, carbon molecular sieves were obtained using the same method as in Example 3. Following the same procedure as in Example 1, when determining the diameter and aspect ratio of the cylindrical particles, it was confirmed that the diameter of the cylindrical particles was 2.0 mm and the aspect ratio was 1:5. Furthermore, following the same procedure as in Example 1, when determining the diameter and aspect ratio of the cylindrical granular carbon molecular sieve, it was confirmed that the diameter of the carbon molecular sieve was 2.0 mm and the aspect ratio was 1:5.

[0230] [Comparative Example 3]

[0231] Except for changing the carrier gas flow rate from 200 L / min to 100 L / min and the benzene content from 7.5 parts by mass to 4.0 parts by mass during the firing process, carbon molecular sieves were obtained using the same method as in Example 3. Following the same procedure as in Example 1, the diameter and aspect ratio of the cylindrical particles were determined, confirming a diameter of 2.0 mm and an aspect ratio of 1:5. Furthermore, following the same procedure as in Example 1, the diameter and aspect ratio of the cylindrical granular carbon molecular sieves were determined, confirming a diameter of 2.0 mm and an aspect ratio of 1:5.

[0232] [Comparative Example 4]

[0233] Except for changing the carrier gas flow rate from 200 L / min to 75 L / min and the benzene content from 7.5 parts by mass to 4.0 parts by mass during the firing process, carbon molecular sieves were obtained using the same method as in Example 3. Following the same procedure as in Example 1, the diameter and aspect ratio of the cylindrical particles were determined, confirming a diameter of 2.0 mm and an aspect ratio of 1:5. Furthermore, following the same procedure as in Example 1, the diameter and aspect ratio of the cylindrical granular carbon molecular sieves were determined, confirming a diameter of 2.0 mm and an aspect ratio of 1:5.

[0234] [Comparative Example 5]

[0235] Except for changing the carrier gas flow rate from 200 L / min to 50 L / min and the benzene content from 7.5 parts by mass to 4.0 parts by mass during the firing process, carbon molecular sieves were obtained using the same method as in Example 3. Following the same procedure as in Example 1, when determining the diameter and aspect ratio of the cylindrical particles, it was confirmed that the diameter of the cylindrical particles was 2.0 mm and the aspect ratio was 1:5. Furthermore, following the same procedure as in Example 1, when determining the diameter and aspect ratio of the cylindrical granular carbon molecular sieves, it was confirmed that the diameter of the carbon molecular sieves was 2.0 mm and the aspect ratio was 1:5.

[0236] [Comparative Example 6]

[0237] Except for changing the activation time for adhering water vapor to the cylindrical particles in the activation process from 100 minutes to 60 minutes, changing the carrier gas rate in the firing process from 200 L / min to 50 L / min, and changing the benzene content from 7.5 parts by mass to 2.0 parts by mass, carbon molecular sieves were obtained using the same method as in Example 3. Following the same procedure as in Example 1, when determining the diameter and aspect ratio of the cylindrical particles, it was confirmed that the diameter of the cylindrical particles was 2.0 mm and the aspect ratio was 1:5. Furthermore, following the same procedure as in Example 1, when determining the diameter and aspect ratio of the cylindrical granular carbon molecular sieves, it was confirmed that the diameter of the carbon molecular sieves was 2.0 mm and the aspect ratio was 1:5.

[0238] [Comparative Example 7]

[0239] Except for changing the activation time for adhering water vapor to the cylindrical particles from 100 minutes to 40 minutes in the activation process and changing the benzene content from 7.5 parts by mass to 3.0 parts by mass in the firing process, carbon molecular sieves were obtained using the same method as in Example 3. Following the same procedure as in Example 1, the diameter and aspect ratio of the cylindrical particles were determined, confirming a diameter of 2.0 mm and an aspect ratio of 1:5. Furthermore, following the same procedure as in Example 1, the diameter and aspect ratio of the cylindrical granular carbon molecular sieves were determined, confirming a diameter of 2.0 mm and an aspect ratio of 1:5.

[0240] [Evaluation Method]

[0241] [Half-width of the main peak in the oxygen adsorption rate constant distribution]

[0242] Using the carbon molecular sieves obtained in the examples and comparative examples, the half-width (in seconds) of the main peak of the oxygen adsorption rate constant distribution was determined by the method described above. 1 ).

[0243] [Specific surface area]

[0244] The specific surface area (m²) was determined by the BET method from the CO2 adsorption isotherm at 25℃. 2 / g) was obtained by the following operation. That is, using a specific surface area / pore distribution measuring device (BELSORP (registered trademark)-MAX (trade name) manufactured by MicrotracBEL (Co., Ltd.), the carbon molecular sieves obtained in the examples and comparative examples were heated at 250°C for 3 hours under reduced pressure (vacuum degree: 0.1 kPa or less), and then the carbon dioxide adsorption isotherm of the carbon molecular sieves at 25°C was measured.

[0245] Using the obtained carbon dioxide adsorption isotherm, BET analysis was performed, and the straight line in the region where the relative pressure P / P0 = 0.01 or higher and 0.1 or lower was calculated from the obtained curve using the multi-point method. The specific surface area was then calculated from this straight line.

[0246] [The maximum center of the main peak in the oxygen adsorption rate constant distribution]

[0247] Using the carbon molecular sieves obtained in the examples and comparative examples, the maximum center (seconds) of the main peak of the oxygen adsorption rate constant distribution was determined by the method described above. 1 ).

[0248] [Volume of pores with an inlet diameter of 0.37 nm or more and 0.46 nm or less]

[0249] Using the carbon molecular sieves obtained in the examples and comparative examples, the volume (mL / g) of the pores with a pore inlet diameter of 0.37 nm or more and 0.46 nm or less, determined by the molecular probe method, was obtained by the method described above.

[0250] [Fill Density]

[0251] The carbon molecular sieves obtained in the examples and comparative examples were used to determine the packing density (g / mL) according to JIS K1474 (2014) 7.8.

[0252] [Compressive strength]

[0253] Using the carbon molecular sieves obtained in the examples and comparative examples, the compressive strength per unit area (N / mm²) of the carbon molecular sieves was determined. 2 ).

[0254] The compressive strength per unit area of ​​the cylindrical granular carbon molecular sieve was determined as follows. First, 30 obtained carbon molecular sieves were randomly sampled, and the diameter D (mm) and axial length H (mm) of the cylinder in one of the carbon molecular sieves were measured using vernier calipers. Then, the compressive strength of the carbon molecular sieve was measured using a wooden durometer (manufactured by Fujiwara Corporation, product number 043019-A). Specifically, the compressive strength was determined as follows: Using the wooden durometer, a force was slowly applied in a direction perpendicular to the axial direction of the obtained cylindrical granular carbon molecular sieve, and the force applied when the carbon molecular sieve broke was taken as the compressive strength F (N). The value obtained by dividing the compressive strength by the product of the cylinder diameter D (mm) and the cylinder axial length H (mm) (F / (D×H)) was taken as the compressive strength F' (N / mm²) per unit area. 2 The above measurements were performed on 30 carbon molecular sieves, and their average value was used as the compressive strength per unit area of ​​the carbon molecular sieve.

[0255] [Evaluation of gas separation performance in oxygen and nitrogen]

[0256] The gas separation performance of oxygen and nitrogen is based on the nitrogen production (Nm³) per ton of carbon molecular sieve obtained by a nitrogen generation device using pressure swing adsorption. 3 The evaluation is based on ( / h / t) and nitrogen yield (%).

[0257] Furthermore, let M(t) be the mass of the carbon molecular sieve used in the nitrogen generating unit, and Q(Nm³) be the product nitrogen production rate per hour. 3 The nitrogen production per 1 t of carbon molecular sieve is expressed by the following formula (6).

[0258] Nitrogen generation of product (Nm³) 3 / h / t)=Q(Nm 3 / h) / M(t)···(6)

[0259] Nitrogen yield represents the proportion of nitrogen that can be separated and recovered from the nitrogen in the supplied feed gas, and is expressed by the following formula (7).

[0260] Nitrogen yield (%) = 100 × (product nitrogen production per hour (NL / h) / (product nitrogen production per hour (NL / h) + exhaust gas volume per hour (NL / h)) ···(7)

[0261] In addition, as a nitrogen generating device, such as Figure 7 The gas separation device shown in the schematic diagram shall be operated according to the following operating procedures.

[0262] First, in the gas separation unit, valves 13a, 13b, 14a, 14b, 15, 16a, 16b, and 18 are closed. Next, raw material air compressed by compressor 11 is supplied to raw material tank 12, and valve 13a is opened to introduce the air into adsorption tower A. Then, oxygen is adsorbed in adsorption tower A, and valve 16a is opened, thereby supplying unadsorbed gas (mainly nitrogen) to product tank 17 through valve 16a. Afterwards, valve 16a is closed, and valve 18 is opened, thereby venting the nitrogen-dominant gas from product tank 17. At this time, adsorption tower A is pressurized. Simultaneously, the same operation as above is performed to pre-vent the oxygen adsorbed in adsorption tower B. That is, by opening valve 14b, the oxygen adsorbed in adsorption tower B is discharged through valve 14b from 19. At this time, adsorption tower B reaches atmospheric pressure. Maintaining adsorption towers A and B in this state, after 59 seconds, close valves 13a and 14b, and open valve 15, thereby equalizing the pressure in adsorption towers A and B. The equalization time is 1 second. After equalization, close valve 14b, and open valves 13b, 16b, and 14a, allowing the adsorbed oxygen from adsorption tower A to be discharged from outlet 19 and undergo oxygen adsorption in adsorption tower B. Repeat this operation to continuously extract product nitrogen.

[0263] Furthermore, the opening degree of valve 18 remains constant throughout the series of operations. By adjusting the opening degree of valve 18, the output flow rate of product nitrogen can be changed, thereby adjusting the product nitrogen concentration.

[0264] Here, in this specification, the nitrogen concentration of the product is set to 99.99%.

[0265] [Evaluation of gas separation performance in carbon dioxide and methane]

[0266] The gas separation performance of carbon dioxide and methane is based on the methane production per ton of carbon molecular sieve (Nm³) obtained by a methane generation device using pressure swing adsorption. 3 The yield was evaluated using (h / t) and methane yield (%).

[0267] Furthermore, let M1(t) be the mass of the carbon molecular sieve used in the methane generating unit, and Q1(Nm³) be the product methane production rate per hour. 3 The amount of methane produced per 1 t of carbon molecular sieve is expressed by the following formula (8).

[0268] Product methane production (Nm³) 3 / h / t)=Q1(Nm 3 / h) / M1(t)···(8)

[0269] The methane yield represents the proportion of methane that can be separated and recovered from the methane in the supplied feed gas, and is expressed by the following formula (9).

[0270] Methane yield (%) = 100 × (product methane production per hour (NL / h) / (product methane production per hour (NL / h) + exhaust gas volume per hour (NL / h)) ···(9)

[0271] In addition, as a methane generating device, using such Figure 8 The gas separation device shown in the schematic diagram shall be operated according to the following operating procedures.

[0272] First, in the gas separation unit, valves 26a, 26b, 27a, 27b, 28, 29a, 29b, and 31 are closed. Next, valves 26a, 29b, and 31 are opened, introducing the mixture of carbon dioxide and methane, the feed gas, from the feed gas tank 25 into adsorption tower C. Then, carbon dioxide is adsorbed in adsorption tower C, and the unadsorbed gas (mainly methane) is supplied to product tank 30 through valve 29a. The product gas, mainly methane, is obtained in product tank 30 through valve 31. At this time, adsorption tower C is pressurized. Simultaneously, the same operation as above is performed to pre-discharge carbon dioxide adsorbed in adsorption tower D. That is, by opening valve 27b, the carbon dioxide adsorbed in adsorption tower D is discharged by vacuum pump 32 through valve 27b. At this time, adsorption tower D is under vacuum. Adsorption towers C and D are maintained in this state for 59 seconds, then valves 26a, 29a, and 27b are closed, and valve 28 is opened, thereby equalizing the pressure in adsorption towers C and D. The equalization time is set to 1 second. After equalization, the adsorbed carbon dioxide from adsorption tower C is discharged through vacuum pump 32 by opening valves 26b, 29b, and 27a, and carbon dioxide adsorption continues in adsorption tower D. By repeating this operation, product methane is continuously extracted.

[0273] Furthermore, the opening degree of valve 31 remains constant throughout the series of operations. By adjusting the opening degree of valve 31, the output flow rate of product methane can be changed, thereby adjusting the product methane concentration.

[0274] Here, in this specification, the methane concentration of the product is set to 97%, and the methane concentration of the raw material gas is set to 60%.

[0275] [Evaluation of gas separation performance in chain olefins and chain alkanes]

[0276] Gas separation performance in chain olefins and chain alkanes is based on the amount of chain olefins produced per ton of carbon molecular sieve (Nm³) obtained by a chain olefin generating unit using pressure swing adsorption. 3 The yield was evaluated using ( / h / t) and the yield of chain olefins (%).

[0277] Furthermore, with the mass of the carbon molecular sieve used in the chain olefin generating device as M2(t) and the product chain olefin production rate per hour as Q2(Nm3 / h), the product chain olefin production rate per 1t carbon molecular sieve is expressed by the following formula (10).

[0278] Product chain olefin production (Nm 3 / h / t)=Q2(Nm 3 / h) / M2(t)···(10)

[0279] The yield of chain olefins represents the proportion of chain olefins that can be separated and recovered from the chain olefins in the supplied feed gas, and is expressed by the following formula (11).

[0280] Chain olefin yield (%) = 100 × (chain olefin production per hour (NL / h) / (chain olefin production per hour (NL / h) + exhaust gas volume per hour (NL / h)) ···(11)

[0281] In addition, as a chain olefin generating device, such as Figure 9 The gas separation device shown in the schematic diagram shall be operated according to the following operating procedures.

[0282] First, in the gas separation unit, valves 34a, 34b, 35a, 35b, 36, 37a, 37b, 38, and 41 are closed. Next, valves 34a, 37b, and 38 are opened, introducing the mixed gas of chain olefins and chain alkanes, which serves as the feed gas, from the feed gas tank 33 into the adsorption tower E. Then, the chain alkanes are adsorbed in the adsorption tower E, and the unadsorbed gas (mainly chain alkanes) is discharged through valve 37a and valve 38. At this time, the adsorption tower E is under pressure. Simultaneously, the same operation as above is performed to pre-discharge the chain olefins adsorbed in the adsorption tower F. That is, by opening valve 35b, the chain olefins adsorbed in the adsorption tower F are discharged through valve 35b by the vacuum pump 39 and supplied to the product tank 40. At this time, the adsorption tower F is under vacuum. Maintaining adsorption towers E and F in this state, after 120 seconds, close valves 34a, 37a, and 35b, and open valve 36 to equalize the pressure in adsorption towers E and F. The equalization time is set to 1 second. After equalization, by opening valves 34b, 37b, and 35a, the adsorbed chain olefins from adsorption tower E are discharged through vacuum pump 39 and supplied to product tank 40 for further adsorption of chain olefins in adsorption tower F. By repeating this operation, the product chain olefins are continuously extracted.

[0283] Furthermore, the opening degree of valve 41 remains constant throughout the series of operations. By adjusting the opening degree of valve 41, the output flow rate of the product chain olefin can be changed, thereby adjusting the concentration of the product chain olefin.

[0284] In this embodiment, propylene is used as a chain olefin and propane is used as a chain alkane. The propylene concentration of the product is set to 99.5%, and the propylene concentration of the raw material gas is set to 20%.

[0285] [Measurement Results]

[0286] The results for the half-maximum width of the main peak of the oxygen adsorption rate constant distribution, specific surface area, maximum center of the main peak of the oxygen adsorption rate constant distribution, volume of pores with inlet diameters greater than 0.37 nm and less than 0.46 nm, packing density, and compressive strength per unit area of ​​the carbon molecular sieve are shown in Table 1. In addition, the results for product nitrogen production, product nitrogen yield, product methane production, product methane yield, product propylene production, and product propylene yield are shown in Table 2.

[0287]

[0288]

[0289] As shown in Tables 1 and 2, the half-width of the main peak of the oxygen adsorption rate constant distribution is 0.35 s⁻¹. 1 Furthermore, the specific surface area, calculated using the BET method from the CO2 adsorption isotherm at 25°C, is 300 m². 2 / g or more and 600m 2 The carbon molecular sieves with a density of less than / g (Examples 1-8) showed significantly improved gas separation performance compared to carbon molecular sieves that did not meet the above conditions (Comparative Examples 1-5).

[0290] That is, the half-width of the main peak of the oxygen adsorption rate constant distribution is 0.35 s⁻¹. 1 The specific surface area, calculated using the BET method from the CO2 adsorption isotherm at 25℃, is 300 m². 2 / g or more and 600m 2 Compared with carbon molecular sieves that do not meet the above conditions, carbon molecular sieves with a density of less than / g exhibit significantly improved gas separation performance between oxygen and nitrogen, between carbon dioxide and methane, and between propylene and propane.

[0291] This application is based on Japanese Patent Application No. 2022-208875, filed on December 26, 2022, the contents of which are incorporated herein by reference.

[0292] Industrial practicality

[0293] The carbon molecular sieve according to this embodiment is suitable for separating low-molecular-weight gases using pressure swing adsorption or temperature swing adsorption. That is, the carbon molecular sieve is suitable, for example, for use in gas separation devices.

[0294] Symbol Explanation

[0295] 1: Valve; 2: Valve; 3: Valve; 4: Pressure sensor; 5: Gas storage unit; 6: Sample cell; 7: Carbon molecular sieve; 8: Inlet; 9: Outlet; A: Adsorption tower; B: Adsorption tower; 11: Compressor; 12: Raw material tank; 13a: Valve; 13b: Valve; 14a: Valve; 14b: Valve; 15: Valve; 16a: Valve; 16b: Valve; 17: Product tank; 18: Valve; 19: Outlet; 20: Glass container; 21: Hole; 22: Weighing bottle containing carbon molecular sieve; 23: Perforated plate; 24: Full Petri dishes containing carbon disulfide or chloroform; C: Adsorption tower; D: Adsorption tower; 25: Raw material gas tank; 26a: Valve; 26b: Valve; 27a: Valve; 27b: Valve; 28: Valve; 29a: Valve; 29b: Valve; 30: Product tank; 31: Valve; 32: Vacuum pump; E: Adsorption tower; F: Adsorption tower; 33: Raw material gas tank; 34a: Valve; 34b: Valve; 35a: Valve; 35b: Valve; 36: Valve; 37a: Valve; 37b: Valve; 38: Valve; 39: Vacuum pump; 40: Product tank; 41: Valve.

Claims

1. A carbon molecular sieve, wherein the half-width of the main peak of the oxygen adsorption rate constant distribution of the carbon molecular sieve is less than 0.35 s⁻¹, and the specific surface area determined by the BET method from the CO₂ adsorption isotherm at 25 °C is 300 m². 2 / g or more and 600m 2 / g or less.

2. The carbon molecular sieve according to claim 1, wherein, The target gas for separation is air, from which oxygen is selectively adsorbed.

3. The carbon molecular sieve according to claim 1, wherein, The target gas for separation is a mixture of carbon dioxide and methane, from which carbon dioxide is selectively adsorbed.

4. The carbon molecular sieve according to claim 1, wherein, The target gas for separation is a mixture of linear olefins and linear alkanes, from which linear olefins are selectively adsorbed.

5. The carbon molecular sieve according to claim 4, wherein, The gas to be separated is a mixture of propylene and propane, from which propylene is selectively adsorbed.

6. The carbon molecular sieve according to any one of claims 1 to 5, wherein, The maximum center of the main peak of the oxygen adsorption rate constant distribution is above 0.030 s⁻¹ and below 0.250 s⁻¹.

7. The carbon molecular sieve according to any one of claims 1 to 5, wherein, The volume of the pores with an inlet diameter of 0.37 nm or more and 0.46 nm or less, determined by the molecular probe method, is greater than 0.150 mL / g.

8. The carbon molecular sieve according to any one of claims 1 to 5, wherein, The filling density, as determined according to section 7.8 of JIS K1474 (2014), is above 0.660 g / mL and below 0.730 g / mL.

9. The carbon molecular sieve according to any one of claims 1 to 5, wherein, The compressive strength per unit area is 8.5 N / mm². 2 Above and 30.0 N / mm 2 the following.

10. The carbon molecular sieve according to any one of claims 1 to 5, comprising non-graphitizable carbon.

11. A method for manufacturing a carbon molecular sieve according to any one of claims 1 to 5, comprising: The process of carbonizing raw materials to obtain carbides; An activation process for activating the carbide to obtain an activated product; as well as The firing process for firing the activated material.

12. A gas separation device for separating oxygen from air by pressure swing adsorption. The gas separation device uses the carbon molecular sieve according to claim 1 as the adsorbent in the pressure swing adsorption method.

13. A gas separation apparatus for separating carbon dioxide from a mixture of carbon dioxide and methane by pressure swing adsorption. The gas separation device uses the carbon molecular sieve according to claim 1 as the adsorbent in the pressure swing adsorption method.

14. A gas separation apparatus for separating chain olefins from a mixture of chain olefins and chain alkanes by pressure swing adsorption. The gas separation device uses the carbon molecular sieve according to claim 1 as the adsorbent in the pressure swing adsorption method.

15. A gas separation apparatus for separating propylene from a mixture of propylene and propane by pressure swing adsorption. The gas separation device uses the carbon molecular sieve according to claim 5 as the adsorbent in the pressure swing adsorption method.

16. A gas separation device for separating oxygen from air by temperature-switching adsorption. The gas separation device uses the carbon molecular sieve according to claim 1 as the adsorbent in the temperature-switching adsorption method.

17. A gas separation apparatus for separating carbon dioxide from a mixture of carbon dioxide and methane by temperature-switching adsorption. The gas separation device uses the carbon molecular sieve according to claim 1 as the adsorbent in the temperature-switching adsorption method.

18. A gas separation apparatus for separating chain olefins from a mixed gas containing chain olefins and chain alkanes by a temperature-switching adsorption method. The gas separation device uses the carbon molecular sieve according to claim 1 as the adsorbent in the temperature-switching adsorption method.

19. A gas separation apparatus for separating propylene from a mixed gas containing propylene and propane by a temperature-switching adsorption method. The gas separation device uses the carbon molecular sieve according to claim 5 as the adsorbent in the temperature-switching adsorption method.

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