JPH0141380B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Application Field] The present invention mainly relates to a separation agent comprising a novel zeolite composition suitable for separating, purifying, or concentrating oxygen and nitrogen gas from a gas mixture comprising oxygen and nitrogen gas by an adsorption method. It is related to. [Object of the Invention] The object of the present invention is to provide a separation agent consisting of an active zeolite composition having a specific composition of Y-type zeolite substituted with divalent metal, which is suitable for the separation and concentration of the above-mentioned gases. There is something to do. [Prior Art] A-type zeolite having a pore diameter of about 5 Å and having a molecular sieving action is widely used in the separation and purification of oxygen and nitrogen gases by adsorption methods. Commercially available MS-5A is exemplified as a typical adsorbent. [Structure of the Invention] In order to improve the separation and concentration of the above-mentioned gases, the present inventor conducted research to increase the adsorption and desorption rate of mainly oxygen and nitrogen gases to zeolite-based adsorbents, and found that the pore diameter Approximately 8Å
A composition in which sodium-type Y-type zeolite is replaced with a certain amount or more of divalent metal has a higher N ₂ /O ₂ adsorption ratio than known zeolites, and also has a higher gas adsorption and desorption rate. Therefore, it has been found that the divalent metal-substituted zeolite composition is extremely effective in separating and concentrating the above-mentioned oxygen and nitrogen gases based on the adsorption method. The present invention will be described in detail as follows. The present invention focuses on the separation, purification, and purification of oxygen and nitrogen gases.
The present invention also relates to an oxygen and nitrogen separating agent made of a divalent metal-substituted zeolite composition that is effective for concentration. The separating agent according to the present invention has the following activity suitable for separating, purifying, and concentrating oxygen and nitrogen gases obtained by replacing ion-exchangeable sodium of Y-type zeolite with divalent metal ions (M ²⁺ ). It is composed of a zeolite-based composition. That is, a zeolite composition in which the sodium contained in the Y-type zeolite is ion-exchanged with calcium in an equivalent fraction of 0.8 or more, strontium in a 0.9 equivalent fraction or more, or barium in a 0.7 equivalent fraction or more. NaCaY (≧0.8) NaSrY (≧0.9) NaBaY (≧0.7) However, the above Y represents Y-type zeolite, and the value in parentheses indicates the equivalent fraction of divalent metal () in the zeolite solid phase. (Total amount of ion-exchangeable metals in the zeolite solid phase: +=
1 equivalent fraction). The Y-type zeolite composition substituted with a divalent metal, which constitutes the separation agent of the present invention, has a pore diameter of about 8 Å.
Type zeolite is ion-exchanged using a solution of water-soluble divalent metal chloride, nitric acid, etc. from room temperature to high temperature (20
~90°C). The optimal content of divalent metals in the three types of zeolite solid phases of NaCaY, NaSrY, and NaBaY of the present invention is as follows. That is, ≧0.8 for NaCaY compositions, ≧0.9 for NaSrY compositions, and ≧0.7 (equivalent fraction) for NaBaY compositions are required to achieve a high separation efficiency for oxygen and nitrogen gases. Between the above lower limit equivalent fraction and the saturation value (=1), when air components are separated by the GC method using activated products of the three types of zeolite compositions mentioned above, oxygen and nitrogen gas The peaks are completely separated, and the S, Q, and R values associated with GC evaluation are
An improvement was observed compared to these values for NaY. It was also confirmed that the adsorption and desorption of air components to the three types of NaMY compositions described above were carried out extremely quickly and under favorable conditions. Furthermore, with the decrease below the above lower limit,
The S, Q, and R values tend to become smaller. Based on this reason, the NaMY3 of the present invention
Numerical limitations in the seed composition were performed as described above. Next, a method for forming a divalent metal-substituted zeolite composition effective for separating, purifying, and concentrating oxygen and nitrogen gases will be described. X type, Y type and/or
Or, in the presence of an inorganic and/or organic binder for a powder or small granular product of a zeolite composition obtained by ion-exchanging the sodium contained in type A zeolite with an alkaline earth metal at an equivalent fraction of 0.7 or more. Wet mixing is performed to obtain a homogeneous mixture, which is then molded into a predetermined shape.The resulting molded product is then dried and finally fired at a temperature range of 400 to 580°C for activation. A molded body of the zeolite composition is produced. Suitable inorganic binders used during molding include colloidal substances such as bentonite, diatomaceous earth, kaolin, colloidal silica, and colloidal alumina. On the other hand, preferred organic binders include crystalline cellulose such as methylcellulose, carboxymethylcellulose, and hydroxyethylcellulose, and molasses. During wet molding, the above-mentioned inorganic and organic binders may be used alone or in combination. The amount of water required in the wet blending process is controlled by the physical properties of the divalent metal-substituted zeolite composition as the raw material, but normally a water content of 20 to 50% is appropriate. Next, the amount of binder used will naturally vary depending on the type of binder and the physical properties of the molding material, but if only an inorganic binder is used, an appropriate amount is 6 to 36% of the zeolite composition material. On the other hand, when only an organic binder is used, the appropriate amount ranges from 1 to 5%. By using the above-mentioned amounts of water and binder, an easily moldable mixture is obtained, which can be used to mold products into spheres, columns, pellets, cylinders, plates, honeycombs, and other shapes. It can be processed into Next, the obtained molded body is dried at around 100°C to adjust its shape, and then calcined in a temperature range below the thermal decomposition initiation temperature of the zeolite composition to purify oxygen and nitrogen gas and A molded body of a divalent metal-substituted zeolite composition suitable for concentration is obtained. The above firing temperature varies depending on the type of zeolite composition used, but in general, 400 to 580°C is appropriate, and 450 to 560°C is a preferred firing temperature range. Below, the effects of using the above-mentioned binder and setting the moisture content of the mixture and the calcination temperature within the above-mentioned ranges are as follows: (i) When producing a molded body made of a zeolite-based composition. When using inorganic binders such as , bentonite, diatomaceous earth, etc.,
Bonds between zeolite fine particles are strengthened. or,
The above-mentioned inorganic binder is thermally stable and does not adversely affect the inherent properties of zeolite even when the molded body is fired at the above-mentioned temperature of 400 to 580°C, and therefore the final product obtained It has the advantage of having almost no adverse effect on the gas adsorption properties of (ii) By using the above-mentioned organic and/or inorganic binders, a homogeneous wet mixture of zeolite can be easily obtained. Furthermore, by using an organic binder, the wet mixture of zeolite can be molded very easily. (iii) If an organic binder is used, the organic binder will be completely thermally decomposed when the molded body is fired in the above-mentioned temperature range, so the inherent adsorption capacity of zeolite will not be reduced by dilution with the binder. It has the advantage of (iv) If an inorganic binder and an organic binder are used together, the amount of the inorganic binder used can be reduced compared to the case where only the inorganic binder is used. (v) As mentioned above, inorganic and/or organic binders are used and the moisture content in the mixture is between 20 and 20%.
Set the firing temperature to 50% and further increase the firing temperature to 400~
By setting the temperature in the range of 580℃, the N ₂ /O ₂ adsorption ratio of the obtained molded product shows an extremely high value.
It becomes possible to produce a molded body with excellent selective adsorption properties. (vi) By using the binder as described above and setting the moisture content and firing temperature within the above range, the adsorption rate and desorption rate of nitrogen or oxygen of the obtained molded product are high. (vii) The molded product obtained has a large specific surface area and is porous, thereby increasing the selective adsorption of oxygen and nitrogen. (viii) The mechanical strength of the obtained molded product is also sufficiently high, and there is no breakage or wear, making it suitable as an adsorbent packed into an adsorption tower. The preferred composition of the zeolite composition to be mixed with the binder is as defined in the present invention described above when Y-type zeolite is used as the starting material. Next, for reference, a zeolite composition having the following composition using type X zeolite or type A zeolite as a starting material will be described. (1) Sodium contained in X-type zeolite is
A zeolite composition ion-exchanged with calcium, strontium and/or barium in an equivalent fraction of 0.8 or more. NaCaX (≧0.8) NaCaX (≧0.8) NaSrX (≧0.8) (2) A zeolite composition in which sodium contained in type A zeolite is ion-exchanged with calcium at an equivalent fraction of 0.9 or more. NaCaZ (≧0.9) However, the above X and Z represent type X zeolite and type A zeolite, respectively. Using an aqueous solution of water-soluble divalent metal chloride, nitrate, etc., an ion exchange reaction is carried out on X-type zeolite (NaX) with a pore diameter of about 10 Å with divalent metal ions at room temperature to high temperature, e.g. 20 to 90°C. NaCaX with a pore size smaller than 10 Å, obtained by
In each case, the content of divalent metal in the three types of zeolite compositions, NaSrX and NaBaX, is at least 0.8 equivalent fraction or more, which increases the separation efficiency of oxygen and nitrogen gases by the selective adsorption method. It is also necessary for The N ₂ /O ₂ adsorption ratio for the above three thermally activated products with such compositions is:
In either case, there is an advantage of an improvement of 5 to 33% compared to that of NaX. Furthermore, the gas chromatographic characteristics of the X-type zeolite substituted with the three types of divalent metals mentioned above are improved compared to those of NaX. That is, the above three types
The chromatographic separation of oxygen and nitrogen gas obtained when air components are separated by gas chromatography (GC) using a NaMX-activated product (≥0.8 equivalent fraction) is different from that when using a NaX-activated product. The gas chromatograph obtained was improved in a more favorable direction by comparison, and the obtained gas chromatograph was further evaluated by measuring the relative resolution (S), relative sharpness (Q), and resolution (R). Both values are the same for the former three types of divalent metal substitutes and for the latter.
It was confirmed that the amount increased significantly compared to NaX. The above S, Q, and R ratings are from WLJones,
The method of R. Kieselbach, Anal.chem., 30 , 1590 (1958) was followed. This tendency of increasing S, Q, and R values is caused by the separation or concentration of oxygen and nitrogen gases from air components etc. using the adsorption method when activated products of the three types of NaMX (≧0.8) are used. By using it as a separation agent, not only can the amount of separation agent used be reduced compared to the amount required for known separation agents, but it also has the effect of significantly shortening the time required for the adsorption process and regeneration process of the adsorption bed. ing. In other words, by using NaMX having the above-mentioned composition, there is an advantage that the above-mentioned target gas can be economically obtained by the adsorption method. In the three NaMX compositions mentioned above, all ≧
The equivalent fraction is limited to 0.8. In the range of equivalent fractions = 0.8 to 1.0, the S, Q, and R values are superior compared to those of NaX, while below the above lower limit, as M decreases, S, Q, R
A tendency for the value to gradually decrease was observed. As a result, the ratio of NaMX in the three types of zeolite compositions was set to 0.8 or more as described above. Next, a case will be described in which a zeolite composition using type A zeolite as a starting material is used. Pore size obtained by performing an ion exchange reaction on type A zeolite with a pore size of approximately 4 Å using a solution of water-soluble calcium chloride, nitrate, etc. at room temperature to high temperature (20 to 90°C). The optimal amount of solid phase calcium in the 5 Å NaCaZ zeolite composition is:
Ca≧0.9 equivalent fraction. Within the range of = 0.9 to 1.0 equivalent fraction in NaCaZ, the N ₂ /O ₂ adsorption ratio (B・E・T method, 760 mmHg;
25°C) tends to increase slightly in proportion to the calcium content, but this ratio is within the range of 3.18 to 3.3. of NaCaZ composition (≧0.9 equivalent fraction)
The N ₂ /O ₂ adsorption ratio is calculated using commercially available molecular sieves.
MS-5A (powder) N ₂ /O ₂ = 3.0 (760 mmHg; 25
It has the characteristic that it is 6-10% higher than that of ℃). This fact is confirmed by using the NaCaZ (≧0.9) composition of Reference Example 2 and using air as a raw material gas by adsorption method.
Furthermore, when separating or concentrating oxygen or nitrogen gas, the difference in selective adsorption can be demonstrated as described above, and the target gas can be easily obtained with higher efficiency compared to known adsorbents of the same type. This clearly shows that. [Example] Next, specific aspects of the present invention will be explained based on Examples, but the present invention is not limited to the Examples unless the gist thereof is exceeded. This example relates to a production example of a NaMY-type zeolite composition obtained by replacing ion-exchangeable sodium of Y-type zeolite (NaY) with a divalent metal (M ²⁺ ). As listed in Table 1, as starting material
Using NaY, 2M SrCl ₂ , 1.8M BaCl ₂ , and
Perform ion exchange by batch method 3 to 4 times using 2M CaCl ₂ aqueous solution to have the composition shown.
NaSrY (≧0.9), NaCaY (≧0.8), and
A NaBaY (≧0.7 equivalent fraction) zeolite composition was prepared. The starting material NaY zeolite in this example is 1.09Na ₂ O・Al ₂ O ₃・3.98SiO ₂・XH ₂ O
A dry powder with the chemical composition of was used. The specific surface area (SSA) of this activated powder was 937 m ² /g. Reference Example 1 Next, Reference Example 1 shows an example of producing a zeolite composition using X-type zeolite as a starting material. This reference example converts the ion-exchangeable sodium of type X zeolite (NaX) into a divalent metal ion (M ²⁺ ).
NaCaX suitable for the separation, purification or concentration of oxygen and nitrogen gases obtained by displacement with
(≧0.8), NaSrX (≧0.8), and NaBaX
(≧0.8 equivalent fraction) of an active zeolite composition. Starting material NaX
The type of zeolite is 1.00Na ₂ O・Al ₂ O ₃・
A dry fine powder with a chemical composition of 2.29SiO ₂ .XH ₂ O was used. This is thermally activated to obtain a specific surface area (S.
SA) was measured and obtained 838 m ² /g. NaX above
On the other hand, as shown in the processing conditions in Table 2,
Ion exchange was performed in batches using 2M SrCl ₂ , 1M BaCl ₂ , and 2M CaCl ₂ aqueous solutions at 60°C for 4 to 30 minutes.
Three to four runs were carried out keeping under stirring for 5 hours to convert to NaSrX, NaBaX, and NaCaX, respectively. Final processing using the batch method has been completed.
NaMX was centrifuged and then washed with water. Washing with water was carried out until chlorine ions disappeared. After washing with water, the NaMX composition is dried at 100 to 110°C.
It was made into a fine powder. Zeolite composition obtained according to Reference Example 1
The composition and yield of NaMX are listed in Table 2. If the zeolite composition obtained in Reference Example 1 is thermally activated to form an anhydride, a separating agent suitable for separating and concentrating oxygen and nitrogen gases can be obtained. Reference Example 2 Reference Example 2 is an example of producing a zeolite composition using A-type zeolite as a starting material. That is,
An active zeolite composition of NaCaZ (≧0.9 equivalent fraction) suitable for the separation, purification and concentration of oxygen and nitrogen gases obtained by replacing the ion-exchangeable sodium of type A zeolite (NaZ) with calcium ions. This relates to an example of manufacturing. In this example, the starting material NaZ zeolite is 1.02Na ₂ O・Al ₂ O ₃・1.92SiO ₂・XH ₂ O
A dry powder with the chemical composition of was used. The specific surface area (SSA) of this activated powder was 665 m ² /g. The ion exchange in this example was carried out using a 2.5M CaCl ₂ aqueous solution and holding it at 60°C for 4 hours under stirring four times to obtain a NaCaZ composition having the composition shown in Table 3. It was done. The thermally activated product had the characteristics described below and was found to be excellent as an oxygen and nitrogen separating agent. Table 4 shows the N ₂ /O ₂ adsorption _ratio of the _zeolite composition obtained in Reference Example 1. The table shows the improvement compared to . Comparative example 1
The N ₂ /O ₂ adsorption ratio of the activated NaX product is 2.81 (760 mm
Hg; 25°C), but the N ₂ /O ₂ adsorption ratio of the activated product of the NaMX type zeolite composition of Reference Example 1 obtained by ion exchange is 2.94 to 3.75.
Therefore, the above adsorption ratio is within the range of
It was found that NaMX provides a 5-33% improvement compared to NaX. Furthermore, NaCaZ of Reference Example 2 (
The N ₂ /O ₂ adsorption ratio of the activated product (=0.9165 equivalent fraction) is 3.18, while that of the same commercial product NS-5A (Comparative Example 2) is in the range of 2.9 to 3.0. Therefore, the former shows a 6 to 10% higher adsorption ratio than the latter. The above fact clearly indicates that the activated products of the zeolite compositions of Reference Examples 1 and 2 can further increase the separation efficiency when used as adsorbents for the purpose of separating and concentrating oxygen and nitrogen gases. Reference Example 3 This reference example relates to a method for producing a molded body of an activated zeolite composition suitable for separating, purifying, and concentrating oxygen and nitrogen gases. As a material for the zeolite composition for molding, a dry powder of NaCaZ composition (=0.9186;=0.0814 equivalent fraction) manufactured according to the method of Reference Example 2 was used.
60Kg was used. 13.8 kg of bentonite fine powder and 1.2 kg of methyl cellulose were added to the above zeolite composition material, and 2 kg was added using a V-mixer.
A mixture was prepared by mixing for 30 minutes. next,
Add water to the above mixture and mix for 3 hours.
It was conducted for 50 minutes. Moisture in the mixture at the end of mixing is 35
Retained at ~36%. Next, the mixture was wet-molded to form 1/16" pellets, and the resulting 1/16" pellets were dried at 100 to 110°C. After further adjusting the length of the dried pellets using a flasher, the above pellets were finally calcined at 530-550°C for 4.5 hours to obtain a molded body of an active zeolite composition. In the main molding, it is used as a fired 1/16″ pellet.
45Kg was obtained. In addition, 1/16″ obtained in this reference example
The physical properties of the molded product were as follows. Average strength of 1/16″ pellets: = 3.04 Kg/pellet Apparent density of 1/16″ pellets: = 1.308 SSA of 1/16″ pellets: 569 m ² /g N/O adsorption ratio of 1/16″ pellets: 3.17 (760mmHg;
25°C) The N ₂ /O ₂ adsorption ratio of the fired 1/16″ pellets obtained in this reference example was 3.17 as described above;
The N ₂ /O ₂ adsorption ratio of commercially available MS-5A, 1/16" pellets is 2.93. As can be seen from this, the 1/16" pellets obtained in this reference example are suitable for separating oxygen and nitrogen gas. It is clear that it is more effective in concentration than commercially available products. In addition, this molded product, NaCaZ,
A GC test was conducted using crushed 1/16" pellets with a particle size distribution of 40 to 60 mesh.
It was found that the oxygen and nitrogen peaks in air were completely separated, and the obtained SQR values were both excellent. Next, the NaMX type zeolite composition obtained in Reference Example 1 and the NaMY type zeolite composition obtained in Examples were molded in exactly the same manner as in Reference Example 3 above, and finally calcined to 1/2 16″ pellets were prepared. Furthermore, NaX (1.00Na ₂ O・Al ₂ O ₃・2.29SiO ₂・
XH ₂ O) powder and NaY (1.09Na ₂ O・Al ₂ O ₃・3.98SiO ₂・XH ₂ O) used as starting material in the examples
The molding of the powder was carried out according to Reference Example 3, and the molded body was finally fired at 530 to 550°C for 4.5 hours to form activated NaX・1/16″ pellets and
NaY・1/16″ pellets were adjusted. Prototype was made.
NaSrX・1/16″ pellets, NaCaX・1/16″ pellets and NaX・1/16″ pellets, NaSrY・1/1
6″ pellets, NaBaY・1/16″ pellets,
Seven types of molded bodies, NaCaY 1/16" pellets and NaY 1/16" pellets, are crushed into coarse particles and then classified into particles in the particle size range of 40 to 60 mesh.
This was used as a sample for GC test. For the GC test,
Gas chromatography filling tube (3φ x 2000mm)
8 to 9 g of a molded body (40 to 60 mesh) of the above zeolite composition was filled into the container. After aging the column at 260° C. for 15 hours, a GC test was conducted under the GC measurement conditions listed in Tables 5 and 6 using air as the test gas and helium as a carrier gas. As shown in Table 5, in the GC test using activated NaSrX and NaCaX molded products, when air was used as the test gas, the oxygen and nitrogen peaks were separated under favorable conditions, and these two It was observed that the S, Q, and R values obtained using the molded body of Comparative Example 1 were increased compared to these values of the NaX molded body of Comparative Example 1. Carrier gas flow rate
S when using NaSrX molded body even if it increases by 4.5 times,
The Q and R values remained almost unchanged. Furthermore, the S, Q, and R values when using the NaCaX molded body show a slight tendency to decrease even if the flow rate of the carrier gas is increased by three times. These facts indicate that the NaMX (M=Sr, Ca) molded body is suitable as an adsorbent for separating and concentrating oxygen and nitrogen gases. Table 6 relates to GC tests using activated NaMY molded products. Under the indicated GC measurement conditions, the S, Q, and
It was found that the and R values were superior to those of Comparative Example 3 when the NaY molded body was used.
Adsorption and desorption of oxygen and nitrogen gases on NaMX-type adsorbents and NaMY-type adsorbents occur more quickly than with known adsorbents, as seen from GC data. It is clear that the above-mentioned type of adsorbent has the characteristic of exhibiting high efficiency in the process of purification. In short, the present invention provides three types of zeolite compositions [NaMY (M=Ca, Sr, Ba)] using Y-type zeolite as a starting material, which are suitable for the separation, purification, and concentration of oxygen and nitrogen gases. Therefore, it is recognized that the adsorption method of the present invention can be widely used in the gas field.

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Claims (1)

[Claims] 1. Sodium contained in Y-type zeolite is
An oxygen and nitrogen separation agent consisting of a zeolite composition ion-exchanged with an alkaline earth metal at an equivalent fraction of 0.7 or more. 2. An oxygen and nitrogen separating agent comprising the zeolite composition according to claim 1, wherein the alkaline earth metal is calcium, strontium and/or barium. 3 The sodium contained in Y-type zeolite is
The zeolite-based composition according to claim 1, which is ion-exchanged with at least 0.8 equivalent fraction of calcium, or at least 0.9 equivalent fraction of strontium, or at least 0.7 equivalent fraction of barium, in which oxygen and nitrogen are ion-exchanged. Separation agent.