A method for separating nitrogen and oxygen by adsorption and a lithium-type x molecular sieve adsorbent and preparation thereof

Abstract

The application discloses an adsorption method for separating nitrogen and oxygen, which is characterized in that the lithium type X molecular sieve adsorbent is prepared by the following steps: (1) mixing NaX molecular sieve and a binder uniformly, rolling into small balls, drying and roasting the small balls to obtain roasted small balls; (2) ion exchanging the roasted small balls in the step (1) with a soluble potassium salt solution to obtain potassium type small balls; (3) ion exchanging the potassium type small balls in the step (2) with a soluble ammonium salt solution to obtain ammonium type small balls; (4) ion exchanging the ammonium type small balls in the step (3) with a soluble lithium salt solution, and the ion exchange is carried out in a double-phase countercurrent mode; after the ion exchange is completed, liquid is discharged and in-situ drying is carried out in sequence to obtain the lithium type X molecular sieve adsorbent; and the double-phase countercurrent exchange is carried out in a column container, air is introduced into the bottom of the container, and the air and the soluble lithium salt solution pass through in countercurrent. The method has a higher nitrogen and oxygen separation coefficient.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of nitrogen-oxygen separation adsorption method and a kind of adsorbent and its preparation, more specifically, the present application relates to a kind of nitrogen-oxygen separation adsorption method that can separate nitrogen and oxygen in air, the lithium type X molecular sieve adsorbent involved and its preparation method. BACKGROUND

[0002] Zeolite molecular sieve is a kind of excellent adsorbent, has very strong adsorption capacity to polar small molecules, has selective adsorption to different molecules in critical diameter, shape, unsaturation etc., and is widely used in many separation fields, especially gas separation industry. Air separation oxygen is realized by using specific zeolite molecular sieve to adsorb nitrogen or oxygen in air. LiX molecular sieve is used in industrial air separation device due to its excellent nitrogen adsorption characteristics.

[0003] Industrial nitrogen-oxygen adsorbent is obtained by mixing LiX molecular sieve obtained by cation exchange of X molecular sieve with clay in a certain proportion, rolling into balls, drying and calcining. The exchange degree of Li ion and the adsorption capacity are important indicators for evaluating the adsorbent. Higher exchange degree and adsorption capacity are beneficial to obtain higher nitrogen-oxygen separation coefficient.

[0004] CN101289196A discloses a preparation method of LiLSX molecular sieve, which comprises preparing LSX zeolite, exchanging LSX into KLSX, adjusting pH value to 8.5 with K2SO4 solution and KOH solution, multiple replacement method, each replacement time is 2 minutes, solution temperature is about 80℃, and the exchange solution after the first few exchanges is used for K + exchange process of the next batch; then using a method similar to the solution of K + exchange into NH4LSX, solution pH value is 8.5; then Li + exchange into LiLSX with LiOH solution at 50℃, while air is introduced and NH3 is discharged. Finally, the finished product is obtained by washing, drying and other treatments, and the Li ion exchange degree is >95%. The method has many processes, long time and complicated process, and the molecular sieve is easy to lose when transferred between steps.

[0005] CN102502694A discloses a preparation method of LiLSX molecular sieve, which comprises first exchanging X molecular sieve raw powder with ammonium salt, then impregnating lithium salt solution onto the molecular sieve by impregnation method, and drying and calcining to obtain Li modified X molecular sieve. The method improves the utilization rate of Li ion, but cannot guarantee that all Li ions are exchanged to ionic sites, and there will be some free lithium salt.

[0006] CN114408941A discloses a method for preparing LiX molecular sieve, which comprises: mixing X molecular sieve with Li + containing recovery solution, pre-exchanging, and filtering; using Li + containing exchange solution to perform 9-15 times of countercurrent exchange treatment on the pre-exchanged X molecular sieve under vacuum condition, recovering the filtrate generated after each countercurrent exchange treatment as Li + containing exchange solution for the next countercurrent exchange treatment, recovering the filtrate generated after the last countercurrent exchange treatment as recovery solution; and drying the X molecular sieve obtained after the countercurrent exchange treatment. SUMMARY

[0007] The inventors found that, compared with LiX molecular sieve, NaX molecular sieve has more stable crystal lattice at high temperature, and has less crystal lattice collapse and higher integrity after high-temperature calcination. In the present application, NaX molecular sieve is first mixed with a binder to prepare small balls, which are then dried and calcined, and then the small balls are sequentially subjected to potassium ion exchange, ammonium ion exchange, and lithium ion exchange with double-phase countercurrent to obtain a lithium type X molecular sieve adsorbent. Compared with the lithium type X molecular sieve adsorbent obtained by first obtaining lithium type molecular sieve and then mixing with a binder and drying and calcination, the molecular sieve lattice of the lithium type X molecular sieve adsorbent has high integrity, large adsorption capacity, and higher nitrogen-oxygen separation coefficient when applied to the adsorption method for nitrogen-oxygen separation.

[0008] Therefore, one of the purposes of the present application is to provide an adsorption method for nitrogen-oxygen separation, which has a better nitrogen-oxygen separation coefficient; the second purpose of the present application is to provide a preparation method of lithium type X molecular sieve adsorbent in the adsorption method for nitrogen-oxygen separation; and the third purpose is to provide the lithium type X molecular sieve adsorbent obtained by the preparation method.

[0009] In order to achieve one of the purposes of the present application, the present application provides an adsorption method for nitrogen-oxygen separation, which is to separate nitrogen and oxygen from air by using lithium type X molecular sieve adsorbent, characterized in that the lithium type X molecular sieve adsorbent is prepared by a method comprising the following steps:

[0010] (1) uniformly mixing NaX molecular sieve and a binder at a mass ratio of 80-95:5-20, rolling and forming into small balls, drying the small balls at 60-110 DEG C, and calcining at 500-700 DEG C to obtain calcined small balls;

[0011] (2) ion exchanging the calcined small balls of step (1) with a soluble potassium salt solution to obtain potassium type small balls;

[0012] (3) ion exchanging the potassium type small balls of step (2) with a soluble ammonium salt solution to obtain ammonium type small balls;

[0013] (4) the ammonium type small balls in step (3) are ion exchanged with a soluble lithium salt solution, the ion exchange is carried out in a two-phase countercurrent exchange mode, and after the ion exchange is completed, liquid is discharged and in-situ drying is carried out in sequence to obtain the lithium type X molecular sieve adsorbent; the two-phase countercurrent exchange is carried out in a column container, air is introduced into the bottom of the container, and the air and the soluble lithium salt solution pass through in countercurrent.

[0014] In order to achieve the second purpose of the present application, the present application further provides a preparation method of a lithium type X molecular sieve adsorbent.

[0015] (a) NaX molecular sieve and a binder are uniformly mixed at a mass ratio of 80-95:5-20, are formed into small balls by rolling, and after the small balls are dried at 60-110 DEG C, the small balls are calcined at 500-700 DEG C to obtain calcined small balls;

[0016] (b) the calcined small balls in step (1) are ion exchanged with a soluble potassium salt solution to obtain potassium type small balls;

[0017] (c) the potassium type small balls in step (2) are ion exchanged with a soluble ammonium salt to obtain ammonium type small balls;

[0018] (d) the ammonium type small balls in step (3) are ion exchanged with a soluble lithium salt solution, the ion exchange is carried out in a two-phase countercurrent exchange mode, and after the ion exchange is completed, liquid is discharged and in-situ drying is carried out in sequence to obtain the lithium type X molecular sieve adsorbent; the two-phase countercurrent exchange is carried out in a column container, air is introduced into the bottom of the container, and the air and the soluble lithium salt solution pass through in countercurrent.

[0019] In order to achieve the third purpose of the present application, the present application further provides a lithium type X molecular sieve adsorbent prepared by the preparation method of the lithium type X molecular sieve adsorbent.

[0020] The nitrogen-oxygen separation adsorption method provided by the present application adopts the lithium type X molecular sieve adsorbent, is prepared by mixing NaX molecular sieve and a binder, drying and calcining the small balls, and then sequentially performing potassium ion exchange, ammonium ion exchange and lithium ion exchange in a two-phase countercurrent mode, has a high nitrogen-oxygen separation coefficient, for example, can reach 6.04-6.14, and the nitrogen-oxygen separation coefficients of a comparative lithium type X molecular sieve adsorbent obtained by adopting a conventional kettle lithium exchange or a comparative lithium type X molecular sieve adsorbent obtained by mixing and drying calcined NaX molecular sieve and a binder are 6.02 and 6.01 respectively.

[0021] The preparation method of the lithium type X molecular sieve adsorbent provided by the present application also has the characteristics of high lithium ion exchange degree and high lithium utilization rate. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1For countercurrent column ion exchange device. DETAILED DESCRIPTION

[0023] The present application relates to a method for separating nitrogen and oxygen by adsorption, which is characterized in that the lithium type X molecular sieve adsorbent is prepared by the following steps:

[0024] (1) NaX molecular sieve is mixed with a binder in a mass ratio of 80-95:5-20, and then the mixture is rolled into small balls, which are dried at 60-110℃ and then calcined at 500-700℃ to obtain calcined small balls;

[0025] (2) The calcined small balls obtained in step (1) are subjected to ion exchange with a soluble potassium salt solution to obtain potassium type small balls;

[0026] (3) The potassium type small balls obtained in step (2) are subjected to ion exchange with a soluble ammonium salt to obtain ammonium type small balls;

[0027] (4) The ammonium type small balls obtained in step (3) are subjected to ion exchange with a soluble lithium salt solution, and the ion exchange is carried out by double-phase countercurrent exchange, and after the ion exchange is completed, the liquid is discharged and the small balls are dried in situ to obtain the lithium type X molecular sieve adsorbent; the double-phase countercurrent exchange is carried out in a column container, air is introduced into the bottom of the container, and the air and the soluble lithium salt solution pass through the container countercurrently.

[0028] In the adsorption method of the present application, the SiO2 / Al2O3 molar ratio of the NaX molecular sieve in step (1) is 2.0-2.15. The binder is at least one of palygorskite, kaolinite, dickite, perlite, refractory stone and halloysite, and is preferably kaolinite. The particle size of the calcined small balls is 300-850 microns.

[0029] In the adsorption method of the present application, step (2) is potassium ion exchange of the calcined small balls in step (1) with a soluble potassium salt solution. The concentration of the soluble potassium salt solution is 1.0-4.0 mol / L. The soluble potassium salt is at least one of potassium chloride, potassium sulfate and potassium nitrate, and is preferably potassium sulfate. The ion exchange in step (2) is carried out at a temperature of 50-100℃, preferably 60-95℃, for 0.5-5 hours, preferably 1-3.5 hours.

[0030] In the adsorption method of the present application, step (3) is ammonium ion exchange of the potassium type small balls after the ion exchange in step (2) with a soluble ammonium salt solution. The concentration of the soluble ammonium salt solution is 1.0-4.5 mol / L. The soluble ammonium salt is at least one of ammonium chloride, ammonium sulfate and ammonium nitrate. The ion exchange in step (3) is carried out at a temperature of 40-80℃, preferably 50-75℃, for 0.5-7 hours, preferably 1-5 hours.

[0031] The ion exchange in steps (2) and (3) is preferably column exchange. When the ion exchange in step (2) is tank exchange, the volume ratio of the soluble potassium salt solution to the potassium-type beads is 5-40, preferably 10-30; when the ion exchange in step (2) is column exchange, the volume space velocity of the soluble potassium salt solution is 2-25 h -1 , preferably 5-20 h -1 ; when the ion exchange in step (3) is tank exchange, the volume ratio of the soluble ammonium salt solution to the potassium-type beads is 5-45, preferably 10-35; when the ion exchange in step (3) is column exchange, the volume space velocity of the soluble ammonium salt solution is 2-25 h -1 , preferably 5-18 h -1 .

[0032] The ion exchange in step (4) is lithium ion exchange of the ammonium-type beads after step (3) with a soluble lithium salt solution, and the concentration of the soluble lithium salt solution is 0.5-2.0 mol / L. The soluble lithium salt in step (4) is lithium chloride or lithium hydroxide, preferably lithium hydroxide. The ion exchange in step (4) is carried out at a temperature of 30-80℃, preferably 40-60℃, and an exchange time of 0.5-10 hours, preferably 1-6 hours; the volume space velocity of the soluble lithium salt solution is 0.5-10 h -1 , preferably 2-6 h -1 . The exchange is carried out in a column container by double-phase countercurrent, air is introduced into the bottom of the container, and the air and the soluble lithium salt solution pass through countercurrently, and the air flow rate is 50-800 L·h -1 , preferably 200-600 L·h -1 . The soluble lithium salt solution in step (4) can be recycled, and the lithium utilization rate can reach 100%. After the ion exchange in step (4) is completed, the air flow rate is maintained, the liquid in the exchange column is discharged, and the discharge rate of the effluent is controlled to be 0.2-4 h -1 .

[0033] The in-situ drying in step (4) is carried out in flowing hot air or nitrogen, and the drying temperature is 20-120℃, preferably 30-80℃, and the drying time is 2-30 hours, preferably 5-24 hours. The in-situ drying is carried out under vacuum conditions, and the vacuum degree (gauge pressure) is -0.02 to -0.08 MPa, preferably -0.04 to -0.08 MPa.

[0034] The lithium-type X molecular sieve adsorbent in the adsorption method of the present application has a sodium oxide content of less than 0.5 mass%, a total content of sodium oxide and potassium oxide of less than 0.8 mass%, and a lithium ion exchange degree of greater than 96%.

[0035] The application will be further described by the following examples, but the application is not limited by the examples.

[0036] Three important indexes for measuring the performance of the adsorbent are oxygen adsorption capacity, nitrogen adsorption capacity and nitrogen-oxygen separation coefficient (nitrogen-oxygen separation coefficient = nitrogen adsorption capacity / oxygen adsorption capacity). The nitrogen and oxygen adsorption capacities are measured by a gas adsorption instrument. When the molecular sieve and the test gas reach adsorption equilibrium, the equilibrium gas adsorption amount at this pressure is obtained.

[0037] The lithium ion exchange degree of the adsorbent is calculated by the following method: the number of lithium ions in unit mass of the adsorbent / the number of cation exchange in unit mass of the adsorbent x 100%. The number of cation exchange is calculated by measuring the Al2O3 content in the molecular sieve by ICP, and then calculating the number of Al atoms. Each aluminum atom corresponds to one cation charge.

[0038] The lithium utilization rate of the adsorbent is calculated by the following method: (the concentration of lithium ions in the solution before exchange - the concentration of lithium ions in the solution after exchange) / the concentration of lithium ions in the solution before exchange x 100.

[0039] The sodium oxide content and potassium oxide content of the adsorbent are measured by ICP inductively coupled plasma ion fluorescence spectrometry, and the lithium ion content of the adsorbent is measured by a flame photometer.

[0040] The preparation method of the NaX molecular sieve in the examples of the application is as follows:

[0041] Sodium hydroxide, potassium hydroxide, deionized water, low-alkalinity sodium metaaluminate solution (Al2O3 mass fraction of 11.0%, Na2O mass fraction of 15.1%) and water glass are added into a reaction kettle, and stirred and mixed uniformly to form a molecular sieve synthesis system. The total molar ratio of the materials in the molecular sieve synthesis system is: SiO2 / Al2O3 = 2.40, M2O / SiO2 = 2.25, H2O / SiO2 = 45, wherein M is K and Na, and K / (K+Na) = 0.23. The above-mentioned molecular sieve synthesis system is transferred into the reaction kettle, and is aged at 70°C for 6 hours and hydrothermally crystallized at 95°C for 12 hours. The obtained solid is washed with deionized water until the pH of the filtrate is 8-9, and is dried at 80°C for 12 hours to obtain the NaX molecular sieve.

[0042] The molar ratio of the NaX molecular sieve can be adjusted by adjusting the molar ratio of SiO2 / Al2O3 in the molecular sieve synthesis system.

[0043] Example 1

[0044] (1) 92 kg (based mass, the same below) of NaX molecular sieve with a SiO2 / Al2O3 molar ratio of 2.00 was mixed with 8 kg of kaolinite to prepare spheres. After sieving, small spheres with a particle size of 300-850 μm were taken, dried at 80℃ for 10 hours and calcined at 540℃ for 4 hours to obtain calcined spheres.

[0045] (2) In Figure 1 The column-type ion exchange apparatus shown uses a 2.0 mol / L potassium chloride solution for 3 hours at 90°C, with an exchange volume hourly space velocity (VHSV) of 15 h⁻¹. -1 No air is introduced during the exchange process, resulting in potassium-type spheres;

[0046] (3) Continue the exchange with 3.0 mol / L ammonium chloride solution at 75°C for 2 hours, with an exchange volume hourly space velocity of 15 h⁻¹. -1 No air is introduced during the exchange process, resulting in ammonium-type microspheres;

[0047] (4) Finally, lithium ion exchange is carried out. Air is introduced into the bottom of the container and the air and soluble lithium salt flow countercurrently. After the exchange is completed, the liquid is drained and dried in situ to obtain lithium-type X molecular sieve adsorbent A. (4) The operating conditions and adsorbent performance are shown in Table 1.

[0048] Example 2

[0049] Lithium-type X molecular sieve adsorbent B was prepared according to the method in Example 1, except for the operating conditions in step (4). The operating conditions in step (4) and the performance results of the adsorbent are shown in Table 1 and Table 2.

[0050] Comparative Example 1

[0051] This comparative example illustrates the situation where NaX molecular sieves are first exchanged for LiX molecular sieves and then molded with a binder.

[0052] A certain amount of NaX molecular sieve powder with a SiO2 / Al2O3 molar ratio of 2.00 was loaded into... Figure 1 In the column-type ion exchange device shown, ion exchange was carried out under the same conditions as steps (2) to (4) of Example 1 to obtain LiX molecular sieve. Then, after molding, drying and calcining under the same conditions as step (1) of Example 1, lithium-type X molecular sieve adsorbent DA-1 was obtained. The operating conditions of lithium exchange and the performance of the adsorbent are shown in Table 1 and Table 2.

[0053] Comparative Example 2

[0054] This comparative example illustrates the case where NaX molecular sieves are first formed with a binder and then subjected to ion exchange, and a batch exchange method is used in lithium ion exchange.

[0055] The ammonium-type microspheres obtained in step 1(3) of Example 1 were exchanged with lithium hydroxide solution in a reactor. After the exchange, they were dried at atmospheric pressure outside the reactor. The amount of LiOH solution, concentration of LiOH solution, exchange temperature, exchange time, drying temperature and drying time used in this comparative example were the same as those in Example 1. Lithium-type X molecular sieve adsorbent DA-2 was obtained. The operating conditions for lithium exchange and the performance of the adsorbent are shown in Tables 1 and 2.

[0056] Example 3

[0057] (1) 85 kg (based mass, the same below) of NaX molecular sieve with a SiO2 / Al2O3 molar ratio of 2.15 was mixed with 15 kg of palygorskite to prepare spheres. After sieving, small spheres with a particle size of 300-850 μm were taken, dried at 100℃ for 8 hours and calcined at 520℃ for 6 hours to obtain calcined spheres.

[0058] (2) In Figure 1 The column-type ion exchange apparatus shown uses a 1.25 mol / L potassium sulfate solution for 1 hour at 90°C, with an exchange volume hourly space velocity (VHSV) of 20 h⁻¹. -1 No air is introduced during the exchange process, resulting in potassium-type spheres;

[0059] (3) Continue to exchange with 1.5 mol / L ammonium sulfate solution at 70℃ for 4 hours, with an exchange volume hourly space velocity of 10 h⁻¹. -1 No air is introduced during the exchange process, resulting in ammonium-type microspheres;

[0060] (4) Finally, lithium ion exchange is carried out. Air is introduced into the bottom of the container and the air and soluble lithium salt flow countercurrently. After the exchange is completed, the liquid is drained and dried in situ in sequence to obtain lithium-type X molecular sieve adsorbent C. (4) The operating conditions and adsorbent performance are shown in Table 1 and Table 2.

[0061] Example 4

[0062] Lithium-type X molecular sieve adsorbent D was prepared according to the method in Example 1, except for the operating conditions in step (4). The operating conditions in step (4) and the performance of the adsorbent are shown in Table 1 and Table 2.

[0063] Comparative Example 3

[0064] This comparative example illustrates the situation where NaX molecular sieves are first exchanged for LiX molecular sieves and then molded with a binder.

[0065] A certain amount of NaX molecular sieve powder with a SiO2 / Al2O3 molar ratio of 2.15 was loaded into... Figure 1In the column-type ion exchange device shown, ion exchange was carried out under the same conditions as steps (2) to (4) of Example 3 to obtain LiX molecular sieve. Then, after molding, drying and calcining under the same conditions as step (1) of Example 1, lithium-type X molecular sieve adsorbent DC-1 was obtained. The operating conditions of lithium exchange and the performance of the adsorbent are shown in Table 1 and Table 2.

[0066] Comparative Example 4

[0067] This comparative example illustrates the case where NaX molecular sieves are first formed with a binder and then subjected to ion exchange, and a batch exchange method is used in lithium ion exchange.

[0068] The ammonium-type microspheres obtained in step 3 of Example 3 were exchanged with lithium hydroxide solution in a reactor. After the exchange, they were dried at atmospheric pressure outside the reactor. The amount of LiOH solution, concentration of LiOH solution, exchange temperature, exchange time, drying temperature and drying time used in this comparative example were the same as those in Example 3. Lithium-type X molecular sieve adsorbent DC-2 was obtained. The operating conditions for lithium exchange and the performance of the adsorbent are shown in Tables 1 and 2.

[0069] Example 5

[0070] (1) 90 kg (based mass, the same below) of NaX molecular sieve with a SiO2 / Al2O3 molar ratio of 2.05 was mixed with 10 kg of halloysite to prepare spheres. After sieving, small spheres with a particle size of 300-850 μm were taken, dried at 110℃ for 4 hours and calcined at 540℃ for 6 hours to obtain calcined spheres.

[0071] (2) In Figure 1 The column-type ion exchange apparatus shown uses a 1.0 mol / L potassium sulfate solution for 3 hours at 90°C, with an exchange volume hourly space velocity (VHSV) of 10 h⁻¹. -1 No air is introduced during the exchange process, resulting in potassium-type spheres;

[0072] (3) Continue to exchange with 2.5 mol / L ammonium chloride solution at 65℃ for 6 hours, with an exchange volume hourly space velocity of 10 h⁻¹. -1 No air is introduced during the exchange process, resulting in ammonium-type microspheres;

[0073] (4) Finally, lithium ion exchange is carried out. Air is introduced into the bottom of the container and the air and soluble lithium salt flow countercurrently. After the exchange is completed, the liquid is drained and dried in situ to obtain lithium-type X molecular sieve adsorbent E. The operating conditions and adsorbent performance of step (4) are shown in Table 1 and Table 2.

[0074] Example 6

[0075] Lithium-type X molecular sieve adsorbent F was prepared according to the method in Example 5, except for the operating conditions in step (4). The operating conditions in step (4) and the performance of the adsorbent are shown in Table 1 and Table 2.

[0076] Comparative Example 5

[0077] This comparative example illustrates the situation where NaX molecular sieves are first exchanged for LiX molecular sieves and then molded with a binder.

[0078] A certain amount of NaX molecular sieve powder with a SiO2 / Al2O3 molar ratio of 2.05 was loaded into... Figure 1 In the column-type ion exchange device shown, ion exchange was carried out under the same conditions as steps (2) to (4) of Example 5 to obtain LiX molecular sieve. Then, after molding, drying and calcining under the same conditions as step (1) of Example 5, lithium-type X molecular sieve adsorbent DE-1 was obtained. The operating conditions of lithium exchange and the performance of the adsorbent are shown in Table 1 and Table 2.

[0079] Comparative Example 6

[0080] This comparative example illustrates the case where NaX molecular sieves are first formed with a binder and then subjected to ion exchange, and a batch exchange method is used in lithium ion exchange.

[0081] The ammonium-type microspheres obtained in step 5(3) were exchanged using a reactor-type lithium hydroxide solution. After the exchange, they were dried at atmospheric pressure outside the reactor. The amount of LiOH solution, concentration of LiOH solution, exchange temperature, exchange time, drying temperature, and drying time used in this comparative example were the same as those in Example 5. Lithium-type X molecular sieve adsorbent DE-2 was obtained. The operating conditions for lithium exchange and the performance of the adsorbent are shown in Tables 1 and 2.

[0082] Table 1

[0083]

[0084] Table 2

[0085]

[0086] As shown in Table 2, the adsorbent of the present invention has a larger adsorption capacity than the comparative adsorbent, and its nitrogen-oxygen separation coefficient is higher when applied to the adsorption method for nitrogen-oxygen separation.

Claims

1. An adsorptive process for the separation of nitrogen and oxygen from air using lithium-type X molecular sieve adsorbent, characterized in that, The lithium type X molecular sieve adsorbent is prepared by a method comprising the following steps: (1) uniformly mixing NaX molecular sieve and a binder at a mass ratio of 80-95:5-20, rolling and forming into small balls, drying the small balls at 60-110 DEG C, and calcining the small balls at 500-700 DEG C to obtain calcined small balls, wherein the particle size of the calcined small balls is 300-850 microns; (2) ion exchanging the calcined small balls in step (1) with a soluble potassium salt solution to obtain potassium type small balls; (3) ion exchanging the potassium type small balls in step (2) with a soluble ammonium salt solution to obtain ammonium type small balls; (4) ion exchanging the ammonium type small balls in step (3) with a soluble lithium salt solution by double-phase countercurrent exchange, and sequentially performing liquid discharge and in-situ drying treatment after the ion exchange to obtain the lithium type X molecular sieve adsorbent; the double-phase countercurrent exchange is performed in a column container, air is introduced into the bottom of the container, and the air and the soluble lithium salt solution pass through countercurrently; In step (2) and (3), the ion exchange is cauldron exchange or column exchange; the sodium oxide content in the lithium type X molecular sieve adsorbent is less than 0.5% by mass, and the total content of sodium oxide and potassium oxide is less than 0.8% by mass.

2. The adsorption process according to claim 1, characterized in that In step (1), the SiO2 / Al2O3 molar ratio of the NaX molecular sieve is 2.0-2.

15.

3. The adsorption process according to claim 1, characterized in that, In step (1), the binder is at least one of palygorskite, kaolinite, dickite, perlite, refractory stone and halloysite.

4. The adsorption process according to claim 1, characterized in that, In step (2), the soluble potassium salt is at least one of potassium chloride, potassium sulfate and potassium nitrate.

5. The adsorption process according to claim 1, wherein In step (2) and (3), the ion exchange is column exchange.

6. The adsorption process according to claim 1, wherein In step (2), the ion exchange is performed at a temperature of 50-100 DEG C for 0.5-5 hours.

7. The adsorption process according to claim 1, wherein In step (2), the ion exchange is performed at a temperature of 60-95 DEG C for 1-3.5 hours.

8. The adsorption process according to claim 1, wherein In step (3), the soluble ammonium salt is at least one of ammonium chloride, ammonium sulfate and ammonium nitrate.

9. The adsorption process according to claim 1, wherein In step (3), the ion exchange is performed at a temperature of 40-80 DEG C for 0.5-7 hours.

10. The adsorption process according to claim 1, wherein In step (3), the ion exchange is performed at a temperature of 50-75 DEG C for 1-5 hours.

11. The adsorption process according to claim 1, characterized in that, In step (4), the soluble lithium salt is lithium chloride or lithium hydroxide.

12. The adsorption process according to claim 1, characterized in that, In step (4), the soluble lithium salt is lithium hydroxide.

13. The adsorption process according to claim 1, wherein The ion exchange in step (4) is carried out at a temperature of 30-80°C for 0.5-10 hours, and the volume space velocity of the soluble lithium salt solution is 0.5-10 h -1 .

14. The adsorption process according to claim 1, wherein The ion exchange in step (4) is carried out at a temperature of 40-60°C for 1-6 hours, and the volume space velocity of the soluble lithium salt solution is 2-6 h -1 .

15. The adsorption process according to claim 1, wherein The air in step (4) has a flow rate of 50-800 L·h -1 .

16. The adsorption process according to claim 1, wherein The air in step (4) has a flow rate of 200-600 L·h -1 .

17. The adsorption process according to claim 1, wherein The lithium ion exchange degree of the lithium type X molecular sieve adsorbent is greater than 96%.

18. The adsorption process according to claim 1, wherein In step (4), the soluble lithium salt solution is repeatedly used in cycles.

19. The adsorption process according to claim 1, wherein After the ion exchange in step (4) is completed, the air flow rate is maintained, the liquid in the exchange column is discharged, and the volume space velocity of the effluent is controlled to be 0.2-4 h -1 .

20. The adsorption process according to claim 1, wherein In step (4), the in-situ drying is performed in flowing hot air or nitrogen, and the in-situ drying is performed at a temperature of 20-120 DEG C for 2-30 hours.

21. The adsorption process according to claim 1, wherein In step (4), the in-situ drying is performed in flowing hot air or nitrogen, and the in-situ drying is performed at a temperature of 30-80 DEG C for 5-24 hours.

22. The adsorption process according to claim 1, wherein In step (4), the in-situ drying is performed under vacuum at a vacuum degree of -0.02 to -0.08 MPa.

23. The adsorption process according to claim 1, wherein In step (4), the in-situ drying is performed under vacuum at a vacuum degree of -0.04 to -0.08 MPa.

24. The adsorption process according to claim 1, wherein When the ion exchange in step (2) is kettle exchange, the volume ratio of the soluble potassium salt solution to the potassium type beads is 5-40; when the ion exchange in step (2) is column exchange, the volume space velocity of the soluble potassium salt solution is 2-25 h -1 ; when the ion exchange in step (3) is kettle exchange, the volume ratio of the soluble ammonium salt solution to the potassium type beads is 5-45; when the ion exchange in step (3) is column exchange, the volume space velocity of the soluble ammonium salt solution is 2-25 h -1 .

25. The adsorption process according to claim 1, wherein When the ion exchange in step (2) is kettle exchange, the volume ratio of the soluble potassium salt solution to the potassium type beads is 10-30; when the ion exchange in step (2) is column exchange, the volume space velocity of the soluble potassium salt solution is 5-20 h -1 ; when the ion exchange in step (3) is kettle exchange, the volume ratio of the soluble ammonium salt solution to the potassium type beads is 10-35; when the ion exchange in step (3) is column exchange, the volume space velocity of the soluble ammonium salt solution is 5-18 h -1 .

26. A method of preparing a lithium-type X molecular sieve adsorbent, characterized by The preparation method comprises the following steps: (a) uniformly mixing NaX molecular sieve and a binder at a mass ratio of 80-95:5-20, rolling and forming into small balls, drying the small balls at 60-110 DEG C, and calcining the dried small balls at 500-700 DEG C to obtain calcined small balls, wherein the particle size of the calcined small balls is 300-850 microns; (b) ion-exchanging the calcined small balls of step (a) with a soluble potassium salt solution to obtain potassium-type small balls; (c) ion-exchanging the potassium-type small balls of step (b) with a soluble ammonium salt solution to obtain ammonium-type small balls; (d) ion-exchanging the ammonium-type small balls of step (c) with a soluble lithium salt solution by double-phase countercurrent exchange, and after the exchange is completed, sequentially performing liquid discharge and in-situ drying treatment to obtain the lithium-type X molecular sieve adsorbent; the double-phase countercurrent exchange is performed in a column-type container, air is introduced into the bottom of the container, and the air and the soluble lithium salt solution pass through countercurrently; wherein the ion-exchange of steps (2) and (3) is kettle-type exchange or column-type exchange; the lithium-type X molecular sieve adsorbent has a sodium oxide content of less than 0.5 mass%, and a total content of sodium oxide and potassium oxide of less than 0.8 mass%.

27. The lithium-type X molecular sieve adsorbent obtained by the preparation method of claim 26.

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