JP4738833B2 - Method for selective adsorption separation of 12CH4 - Google Patents

Description

  The present invention relates to a gas isotope separation method and an isotope-selective adsorbent, and more specifically, a gas molecule having a specific isotope atom as a constituent element from a gas using a specific isotope-selective adsorbent. The present invention relates to a method for separating and concentrating gas by selectively adsorbing and separating by changing the concentration of gas molecules containing a specific isotope atom, and an isotope selective adsorbent for the method.

  Centrifugation is a method for separating specific isotope atoms from elements containing multiple isotope atoms, or for separating molecules containing specific isotope atoms from molecules composed of elements containing multiple isotope atoms. Methods, thermal diffusion methods, gas diffusion methods, distillation methods, separation nozzle methods, laser methods, separation methods using adsorbents, and the like are known. These methods are properly used depending on the target isotope atom, the molecule containing the isotope atom, the separation amount, the concentration of the isotope atom, and the like. However, for example, the centrifugal separation method requires a high-speed rotating device, so the device itself is expensive, maintenance is also troublesome, the thermal diffusion method requires a large amount of energy, and in the gas diffusion method, A high-pressure gas is diffused to a low-pressure side through a membrane having micropores and separated, but both have advantages and disadvantages such as low diffusion separation efficiency.

  Examples of the separation method using an adsorbent include Japanese Patent Application Laid-Open No. 2003-210945, Japanese Patent No. 3462677, and Japanese Patent Application Laid-Open No. 2004-89767. Among them, in the technique disclosed in Japanese Patent Application Laid-Open No. 2003-210945, a mixed gas containing a molecular or atomic first gas is mixed with the molecular diameter of the first gas or n times the atomic diameter (n = 1, 2, 3, 4). The isotope gas is separated by passing through activated carbon or a porous complex having a pore size close to.

  In the technology of Japanese Patent No. 3462777 (hereinafter referred to as 677), an adsorbent whose micropore size is close to the molecular diameter of the isotope gas is used, and the adsorption amount of the isotope gas reaches the saturated adsorption amount. The adsorption process is completed before the adsorption process, and the adsorption rate of the isotope gas with a small mass number is higher than the adsorption rate of the isotope gas with a large mass number. Separation is achieved by increasing the ratio of body gas to that in the gas phase. And as a premise, when the size of the pore entrance in zeolite (ie, the window diameter) is brought close to the molecular diameter of the gas, the adsorption rate of the isotope molecule having the larger mass number is significantly reduced. It is believed that the fact that the adsorption rate of the isotope molecule having the smaller mass number does not decrease so much has been found.

  Japanese Patent Application No. 2002-251080 [hereinafter referred to as 080 application]. In the priority date of the present application (February 16, 2004, published as JP-A-2004-89767)], as an isotope-selective adsorbent, Na-A type in which at least a part is substituted with Ca or Zn The zeolite heat-treated at a temperature of 650 ° C. to 800 ° C., pentasil zeolite, and mordenite are described. Of these, mordenite is used as it is without performing ion exchange (0023 of the 080 application). Paragraph).

JP 2003-210945 A Japanese Patent No. 3462677 Japanese Patent Application No. 2002-251080 (Japanese Patent Laid-Open No. 2004-89767)

  As described above, all of the conventional isotope separation methods have advantages and disadvantages. However, since the technique of No. 677 and the technique of No. 080 application are separation by an adsorbent, the apparatus itself is simple and the operation is simple. It is a technology that is interesting from a practical point of view. However, the publication No. 677 discloses a carbon molecular sieve 3A having Na-A type zeolite as an adsorbent and a window having the same size [3.8 to 4 mm (0.38 to 0.4 nm)]. Only two are described.

  Therefore, the present inventors further pursued including the additional test on the premise of the technology of No. 677, and unexpectedly from the technology of No. 677, Na-A zeolite and carbon molecular sieve However, only a specific zeolite, mordenite-type zeolite, was found to be very effective for isotope separation among many adsorbents. Based on this fact, many more detailed experiments were conducted, and research and examination were continued. As a result, it was found that mordenite type zeolite carrying a specific cation by ion exchange was more effective.

  The present invention has been made on the basis of such results, and a gas isotope separation method and isotope-selective adsorbent using a mordenite-type zeolite carrying a specific cation as an ion exchange as an adsorbent for isotope separation. Is intended to provide.

  The present invention (1) is a method for separating a gas composed of an element containing a plurality of isotopes. Further, as an isotope selective adsorbent, a cation composed of a metal ion or ammonium ion selected from Group 1, Group 2, Group 8 to Group 10, Group 11, Group 12, Group 13 and Lanthanoid other than Na is ion exchange supported. Using the mordenite-type zeolite, gas molecules having a specific isotope atom as a constituent element in the gas are selectively adsorbed and separated from the mordenite-type zeolite having the cation.

  The present invention (2) is an isotope selective adsorbent for separating a gas composed of an element containing a plurality of isotopes. And it consists of a mordenite type zeolite carrying a metal ion selected from Group 1, Group 2, Group 8-10, Group 11, Group 12, Group 13, Lanthanoids other than Na, or a cation composed of ammonium ions. Features.

The present invention (3) is a method for separating a gas composed of an element containing a plurality of isotopes. And, using a mordenite type zeolite carrying ion exchange supported cations (excluding Na ⁺ ) having an ionic radius of 0.07 nm or more and 0.15 nm or less as an isotope selective adsorbent, A gas molecule having a specific isotope atom as a constituent element in a gas is selectively adsorbed and separated.

Further, the present invention (4) is an isotope selective adsorbent for separating a gas composed of an element containing a plurality of isotopes. And it is characterized by comprising a mordenite type zeolite carrying ion exchange supported cations (excluding Na ⁺ ) having an ionic radius of 0.07 nm to 0.15 nm.

  As described above, among the present inventions (1) to (4), the isotope-selective adsorbents of the present invention (2) and (4) should be used not only at a low temperature range of 0 ° C. or lower, but particularly at a room temperature exceeding 0 ° C. In addition, the gas isotope separation methods of the present invention (1) and (3) can be performed not only at a low temperature range of 0 ° C. or lower, but also at a room temperature exceeding 0 ° C. in particular.

  The present invention (5) is a method for separating a gas composed of an element containing a plurality of isotopes at a room temperature exceeding 0 ° C. And, using Na-mordenite type zeolite as an isotope selective adsorbent, selectively adsorbing and separating gas molecules having a specific isotope atom of gas as a constituent element with respect to the Na-mordenite type zeolite. It is characterized by. The present invention (6) is an isotope selective adsorbent for separating a gas composed of an element containing a plurality of isotopes at a room temperature exceeding 0 ° C. And it consists of a Na-mordenite type zeolite.

Here, the "isotope separation of gas" in the present specification and claims, e.g. Speaking of methane from methane one ¹³ CH _^4/12 CH ₄ content ratio, ¹³ CH ₄ and ¹² CH ₄ One of them is selectively adsorbed and separated to produce methane in which one of ¹³ CH ₄ and ¹² CH ₄ is concentrated, and “isotope-selective adsorbent” It means an adsorbent that selectively adsorbs a molecule containing a specific isotope atom among molecules composed of elements containing a plurality of isotope atoms.

According to the present invention, when performing isotope separation of gas, by using a mordenite type zeolite carrying a specific cation as an isotope selective adsorbent, for example, a C isotope ( ¹³ C and Hydrocarbons containing a specific isotope ( ¹³ C or ¹² C) from hydrocarbons such as methane containing ¹² C) can be effectively separated and concentrated not only at low temperatures but also at room temperature. In addition, the present invention is very useful in practice because the apparatus for carrying out it is simple and easy to operate.

  As the isotope-selective adsorbent used in the gas isotope separation method in the present invention, only mordenite-type zeolite is effective, and in particular, mordenite-type zeolite carrying a cation by ion exchange is effective. Thereby, the isotope separation of the gas can be effectively performed not only at a low temperature range of 0 ° C. or lower, but particularly at a room temperature exceeding 0 ° C. Here, the room temperature is preferably in the range of more than 0 ° C. and 40 ° C. or less, more preferably in the range of more than 0 ° C. and 30 ° C. or less. There are various types of mordenite-type zeolite having cations, including those having H ions as cations, those having metal ions, and those having ammonium ions. These can be obtained by ion exchange of mordenite type zeolite.

In general, mordenite-type zeolite is obtained as Na-type at the time of synthesis, but can be changed to mordenite-type zeolite having other cations by ion exchange of other cations. Na-mordenite-type zeolite is obtained as a powder at the time of synthesis, but is usually molded for use as an adsorbent. Its molding, after molding using a conventional binder, drying, it is common to firing, but when the firing cations may change at least partially H ^+, in this case the H ⁺ It can be changed to Na-mordenite type zeolite by ion exchange with Na ⁺ .

  In the present invention, among mordenite-type zeolites that carry ions of these cations, mordenite-type zeolites and ammoniums that carry cations of groups 1, 2, 8-10, 11, 12, 12, 13 and lanthanoids by ion exchange A mordenite type zeolite carrying ions by ion exchange is used. Examples of lanthanoids include La and Ce. Among them, a mordenite type zeolite in which a group 1, group 2, group 8 to group 10, or group 11 cation is supported by ion exchange is preferably used.

In the present invention, mordenite-type zeolite in which a cation having an ionic radius of 0.07 to 0.15 nm is ion-exchange-supported is particularly effective. Examples of the cation include Cu ²⁺ , Co ²⁺ , Zn ^2+. Na ⁺ , Ca ²⁺ , Sr ²⁺ , Ag ⁺ , K ⁺ , Ba ^{2+ and the} like. The shape of the mordenite type zeolite carrying the above cation by ion exchange can be used in the form of granules, pellets, tablets and other suitable shapes.

  In the above-mentioned 080 application, mordenite is shown as an isotope-selective adsorbent, but this is not mordenite subjected to ion exchange as described in paragraph 0023 of the 080 application. The isotope-selective adsorbent is considered to be undesirable when it exceeds 0 ° C. (paragraph 0030 of the '080 application), and is used at a temperature of −155 ° C. or more and 0 ° C. or less. In the example of mordenite (Adsorbent No. 21 in Table 1 of the 080 application), it is carried out at a temperature of -130 ° C to -78 ° C. On the other hand, the Na-mordenite type zeolite in the present invention can effectively perform gas isotope separation particularly at room temperature exceeding 0 ° C.

Examples of the gas to be separated by the gas isotope separation method in the present invention include lower hydrocarbons selected from methane, ethane, ethylene, propane and butane, a mixed gas of two or more thereof, carbon dioxide gas, ammonia and the like. In particular, it is very effective in separating ¹² CH ₄ and ¹³ CH ₄ of methane. For example, natural methane contains ¹² CH ₄ and ¹³ CH ₄ as a molecule having a carbon isotope in a ratio of 98.9: 1.1. According to the present invention, a specific cation is supported by ion exchange. ¹² CH ₄ can be selectively adsorbed by the mordenite-type zeolite and can be separated and concentrated by increasing the concentration of ¹³ CH ₄ .

  FIG. 1 is a diagram showing an example of an apparatus configuration for carrying out the present invention. As shown in FIG. 1, basically, it is only necessary to arrange the gas introduction pipe 1 and the separated isotope gas outlet pipe 3 in the container 2 filled with mordenite-type zeolite carrying the specific cation by ion exchange. The isotope separation of the gas is carried out by introducing a specific cation into a mordenite-type zeolite-filled container 2 carrying an ion exchange through a gas introduction pipe 1 and discharging the gas after isotope separation from the outlet pipe 3. . In the case of processing a large amount of gas, the operation may be repeated using the isotope-selective adsorbent of the present invention in an apparatus such as PSA or TSA.

<Progress until the present invention>
As described above, the technique disclosed in Japanese Patent No. 677 is an interesting technique from a practical point of view, such as a simple device used and simple operation. The present inventors have further pursued the results including a follow-up test through rigorous experiments. FIG. 2 shows the apparatus used in this experiment. In FIG. 2, 11 is a gas cylinder, 12 is piping, 13 is a mass flow controller (mass flow controller: MFC), 14 is piping, 15 is a valve disposed in the piping 14, 16 is an adsorbent filling container, 17 is piping, 18 Is a valve arranged in the pipe 17, 19 is a branch pipe branched from the pipe 17, and 20 is a mass spectrometer (MS). The gas to be processed that has exited the gas cylinder 11 is introduced into the adsorbent filling container 16 through the pipe 12, the mass flow controller (MFC) 13, and the pipe 14. The treated gas in the adsorbent-filled container 16 reaches the mass spectrometer 20 from the pipe 17 through the branch pipe 19 and is analyzed there, and if there is any selective adsorption in the adsorbent-filled container 16. The degree is measured.

  Since the experiment using the apparatus of FIG. 2 includes a supplementary test of the technique of No. 677, the experiment is similar to the apparatus of [FIG. 1] of No. 677, which is an experimental apparatus used in No. 677, and its operation. The same is true for as much as possible. In addition, in FIG. 1 of Japanese Patent No. 677, a valve (9, 10), a vacuum pump (11), a flow path (16, 17), an MS (19), etc. are provided. It is used to regenerate the adsorbent. In contrast, in this experiment, regeneration of the adsorbent after the adsorption separation process is performed by circulation of the carrier gas. In addition, in the 677 publication, the analysis of the adsorption separation process uses MS (15) instead of the MS (19). Therefore, the adsorption separation process and its analysis by the experimental apparatus of FIG. 2 are used in the 677 publication. It is exactly the same as those with the experimental equipment.

In FIG. 2, the adsorbent filling container 16 is filled with an adsorbent, the flow rate of the gas to be processed from the gas cylinder 11 is controlled by the mass flow controller 13, passed through the adsorbent filling container 16, and the output after passing through the branch pipe 19. The measurement was carried out by measuring the concentration ratio of ¹³ CH ₄ and ¹² CH _{4 in} the gas with the mass spectrometer 20. The experiment was performed at room temperature (23 ± 5 ° C.), methane having a ratio of ¹² CH ₄ and ¹³ CH ₄ of 50:50 was used as the gas to be treated, and helium was mixed as the carrier. The adsorbent filling container 16 has a diameter of 1/8 ″ (1/8 inch, ie, 3.175 mm), a length of 30 cm, a methane flow rate of 25 mL / min, and a helium flow rate of 25 mL / min. The adsorption pressure at about 0.16 MPa.

Tables 1 and 2 show the experimental results of the present apparatus, and the pore diameters of the adsorbents (activated carbon is the average pore diameter) are also shown. In Tables 1 and 2, the adsorbents in Examples Nos. 1 to 29 are various activated carbons, Example No. 30 is silica, and Examples Nos. 31 to 39 are various zeolites. In Table 1-2, the separation factor, and the gas to be treated in ¹³ CH ₄ ¹² concentration ratio of CH ₄ (outlet side ¹³ CH _^4/12 CH ₄ ratio) and ¹³ CH ₄ in the feed gas to ¹² CH divided by the _fourth concentration ratio (inlet side ¹³ CH ^_4/12 CH ₄ ratio), this point is the same for "separation factor" in Table in Table 3 below.

In the case of 29 types of activated carbons of Example Nos. 1 to 29, including the carbon molecular sieve of Example No. 28, there is no isotope separation effect for methane having an isotope ratio of ¹³ CH ₄ and ¹² CH ₄ of 50:50. I understand. This also applies to the silica of Example No. 30. Table 2 shows the case of zeolite. Of the nine types of zeolites of Example Nos. 31 to 39, only Na-mordenite type zeolite (Example No. 32) shows a separation effect, including Na-A type zeolite, It can be seen that all the other zeolites have no isotope separation effect on methane having an isotope ratio of ¹³ CH ₄ and ¹² CH ₄ of 50:50.

Figure 3-11 is a diagram showing the relationship between the elapsed time for the Table 2 definitive various zeolite and outlet ¹³ CH _^4/12 CH ₄ ratio as a graph. As shown in FIGS. 3 to 11, of the nine types of zeolite, only Na-mordenite type zeolite has a unique adsorption separation ability. That is, as shown as in FIG. ₄ (A), ¹² CH 4 is selectively adsorbed, the gas high ¹³ CH _^4/12 CH ₄ ratio as an exit gas is obtained. Thus, it was confirmed that, among many adsorbents, only Na-mordenite type zeolite (Example No. 32) can separate ¹³ CH ₄ and ¹² CH ₄ of methane. Thus, Na-mordenite type zeolite is also useful in that it exhibits isotope separation ability at room temperature.

  Here, the molecular diameter of methane is 0.38 to 0.4 nm. And the pore diameter of the Na-A type zeolite is 0.41 nm, and the mordenite type zeolite (the same applies to the Na-mordenite type zeolite) has two kinds of pores, each having a pore diameter of 0.65 nm × 0. .70 nm (0.65 nm is the diameter of the minor axis, 0.70 nm is the diameter of the major axis), 0.29 nm × 0.57 nm (0.29 nm is the diameter of the minor axis, and 0.57 nm is the diameter of the major axis) [Published by Kodansha, 1 original author, “Zeolite: Fundamentals and Applications”, 15 pages, 18 pages (March 20, 1988), published by Asakura Shoten, edited by Ono Outdoors, “Encyclopedia of Catalysts”, pages 87-88 559 (November 1, 2000)].

Haraichi, 1 book “Zeolite: Basics and Applications”, pages 15 and 18 (March 20, 1988) Ono Outdoor 2 “Encyclopedia of Catalysts”, pages 87-88, 559 (November 1, 2000)

  Therefore, when the molecular diameter of methane is compared with the pore diameter of Na-A zeolite and the pore diameter of Na-mordenite zeolite, the molecular diameter of methane and the pore diameter of Na-A zeolite are almost the same or close to each other. Yes. On the other hand, the molecular diameter of methane and the pore diameter of the Na-mordenite zeolite are neither coincident nor close to each other, and are not close to an integer multiple of the molecular diameter.

  Based on this fact, the gas isotope selective separation action by the mordenite zeolite having a cation in the present invention is at least the close relationship between the molecular diameter of the gas specified in the 677 gazette and the pore diameter of the mordenite zeolite having a cation. (As defined in the 677 publication, the micropore size of the adsorbent is close to the molecular diameter of the gas), and some mechanism peculiar to the mordenite type zeolite having a cation, for example, the above-mentioned It seems that the pore structure connected by pores having different diameters and other factors are involved.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example, of course, this invention is not limited by these Examples. In this example, the experimental apparatus shown in FIG. 2 is used, and an adsorption separation experiment using this apparatus and the results thereof are shown.

<Example 1>
An adsorbent-filled container having a diameter of 1/8 ″ and a length of 1 m was used as the adsorbent-filled container 16 and filled with Na-A type zeolite and Na-mordenite type zeolite, respectively, and experiments were performed at room temperature (23 ± 5 ° C.). As the gas to be treated, methane having an isotope ratio of ¹² C: ¹³ C = 7: 3 (content of ¹³ CH ₄ = 30% in the total methane) was used, and helium was mixed as a carrier gas for the experiment. The flow rate is 25 mL / min and the flow rate of helium is 25 mL / min Table 3 shows the results of this experiment.

As shown in Table 3, the separation factor in the case of Na-A type zeolite is 1.00, and there is no separation effect. On the other hand, the separation factor in the case of Na-mordenite type zeolite showed a value of 1.12. This clearly exceeds the separation factor of Na-A type zeolite. Thus, the Na-mordenite type zeolite is clearly superior to the Na-A type zeolite due to the isotope separation effect for methane having an isotope ratio of ¹² C: ¹³ C = 7: 3. Obviously.

<Example 2>
The same procedure as in Example 1 was performed except that methane having an isotope ratio of ¹² C: ¹³ C = 9: 1 (content of ¹³ CH ₄ = 10% methane in the total methane) was used as the gas to be treated. . Table 4 shows the results of this experiment. As shown in Table 4, the separation factor in the case of Na-A type zeolite is 1.00, and there is no separation effect. On the other hand, the separation factor in the case of Na-mordenite type zeolite shows a value of 1.06. Thus, the Na-mordenite type zeolite is effective for methane having an isotope ratio of ¹² C: ¹³ C = 9: 1, and shows a significant separation effect. As is clear from the results of Examples 1 and 2, the mordenite-type zeolite has significant separation performance regardless of the ¹³ CH ₄ concentration in methane, which is the gas to be treated.

<Example 3>
Example 3 was carried out in the same manner as Example 1 except for the following conditions. As the adsorbent-filled container 1, an adsorbent-filled container having a diameter of 1/8 "and a length of 30 cm is used. In addition to the H type, various cations, that is, cations having different kinds of elements constituting the salt are used. Experiments were conducted at room temperature (23 ± 5 ° C.) by filling various mordenite-type zeolites supported by ion exchange, and the experiment was conducted using methane ( ¹³ CH _{4 with} an isotope ratio of ¹² C: ¹³ C = 1: 1 as the gas to be treated. Table 5 shows the results of this experiment, and Table 5 shows the ionic radius of each cation.

As shown in Table 5, in the case of mordenite type zeolite having cations, regardless of the type of elements constituting H type and salt, all show a significant isotope separation effect with a separation factor of 1.02 or more. Among these, the cation is Cu ²⁺ , Co ²⁺ , Zn ²⁺ , Na ⁺ , Ca ²⁺ , Sr ²⁺ , Ag ⁺ , K ⁺ , Ba ²⁺ mordenite-type zeolite separation factor of 1.04 or more. . Looking at this in relation to the ionic radius of each cation, the ionic radius of these cations is in the range of 0.07 nm to 0.15 nm, and there is a causal relationship between the separation factor of the mordenite zeolite with these cations. It shows that there is.

That is, the ion radius of H ⁺ is as small as 0.03 nm, and the separation factor of mordenite-type zeolite having H ⁺ is 1.02. The ion radius of Li ⁺ is 0.059 nm, and the separation factor of the mordenite-type zeolite having Li ⁺ is 1.03. On the other hand, the ionic radius of NH ₄ ⁺ is as large as 0.152 nm, the ionic radius of Rb ⁺ is as large as 0.152 nm, and the ionic radius of Cs ⁺ is as large as 0.170 nm. It is.

On the other hand, the ionic radii of Cu ²⁺ , Co ²⁺ , Zn ²⁺ , Na ⁺ , Ca ²⁺ , Sr ²⁺ , Ag ⁺ , K ⁺ , and Ba ²⁺ are all 0.07 nm to 0.15 nm. The separation factor of the mordenite zeolite having these cations is 1.04 or more. Among them, in particular, the separation factor of mordenite zeolite with Ba ⁺ is 1.09, the separation factor of mordenite zeolite with Na ⁺ is 1.10, and the separation factor of mordenite zeolite with Ag ⁺ is 1.11. The value is shown.

< Reference example >
This reference example was carried out in the same manner as in Example 2 except that the adsorption temperature was -70 ° C. Table 6 shows the results of this experiment. As shown in Table 6, the presence / absence of the separation effect at a low temperature of −70 ° C. , and the degree of the effect when it exists, vary depending on the zeolite species and the substituted metal species . However, even in such a low temperature range, the Na-mordenite type zeolite has a separation factor of 1.07 and shows a superior separation effect compared to other zeolites. In general, the molecular sieve effect for separating by utilizing the size of the molecules, but separation effect as is a low temperature increases, according to the results of this reference example, that not due only to the size of the molecular that shows.

The figure which shows the example of an aspect of the apparatus structure which implements this invention The figure which shows the apparatus used in the experiment and Example to reach this invention. Graph showing the adsorption time and the outlet ¹³ CH _^4/12 CH ₄ ratio by li-LSX zeolite Graph showing the adsorption time and the outlet ¹³ CH _^4/12 CH ₄ ratio by Na- mordenite zeolite Graph showing the adsorption time and the outlet ¹³ CH _^4/12 CH ₄ ratio by chabazite-type zeolite Graph showing the adsorption time and the outlet ¹³ CH _^4/12 CH ₄ ratio by Na-A type zeolite Graph showing the adsorption time and the outlet ¹³ CH _^4/12 CH ₄ ratio by Ca-X type zeolite Graph showing the adsorption time and the outlet ¹³ CH _^4/12 CH ₄ ratio by Na-Y type zeolite Graph showing the adsorption time and the outlet ¹³ CH _^4/12 CH ₄ ratio by Na-X type zeolite Graph showing the adsorption time and the outlet ¹³ CH _^4/12 CH ₄ ratio by K-L zeolite Graph showing the adsorption time and the outlet ¹³ CH _^4/12 CH ₄ ratio by H-beta-zeolite

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gas introduction pipe 2 Cation-supported mordenite-type zeolite filling container 3 Gas extraction pipe | tube after isotope separation 11 Gas cylinder 12, 14, 17 Piping 13 Mass flow controller (mass flow controller: MFC)
15 Valve arranged in the pipe 14 16 Adsorbent filling container 18 Valve arranged in the pipe 17 19 Branch pipe branched from the pipe 17 20 Mass spectrometer (MS)

Claims (1)

A method for selective adsorption separation of ¹² CH ₄ in the presence of ¹³ CH ₄ and ¹² CH ₄ by an isotope selective adsorbent, comprising Na ⁺ , Li ⁺ , Cu ²⁺ , Co ²⁺ , Zn ²⁺ , Ca ¹³ CH ₄ and ¹² CH ₄ are present at room temperature against isotope-selective adsorbents composed of mordenite-type zeolites carrying ion exchange-supported cations composed of ²⁺ , Sr ²⁺ , Ag ⁺ , K ⁺ or Ba ^{2+ 12} selective adsorption separation method CH _4, characterized by selective adsorption separation of ¹² CH ₄ through gas.

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