Metal-doped modified zeolite molecular sieve adsorbent as well as preparation method and application thereof

Abstract

The invention discloses a metal-doped modified zeolite molecular sieve adsorbent as well as a preparation method and application thereof. The metal-doped modified zeolite molecular sieve adsorbent comprises a carrier and an active metal component loaded on the carrier, the carrier is a mordenite molecular sieve; the active metal components comprise at least two of Ca, Mg, Ti, Fe, Ni, Co, Cu, Zn, Na and Ag; in the adsorbent, the loading capacity of the active metal component is 0.1%-15%. The adsorbent provided by the invention has good separation performance on CH4 / CO2, CH4 / N2, CO2 / N2 and CH4 / CO2 / N2 mixed gas separation systems, has the advantages of simple synthesis method, strong hydrothermal stability, high selectivity and the like, and can meet the requirements of CH4 purification in unconventional natural gas such as landfill gas, sewage treatment methane gas, agricultural and breeding biogas, coal bed gas, shale gas and shallow biogas, and the like. And the requirements of high-concentration natural gas denitrification, CO2 capture and other scenes can be met.

Description

Technical Field

[0001] The present invention relates to the technical field of adsorption materials, and more specifically, to a metal-doped modified zeolite molecular sieve adsorbent and a preparation method and application thereof. Background Art

[0002] The global warming potential of methane is about 28 times that of CO2, making it the second largest contributor to global warming after CO2. Therefore, improving the extraction efficiency of methane can reduce the emission of other pollutants, thereby promoting the full and efficient development of unconventional gas fields and achieving clean and efficient utilization of natural gas resources.

[0003] At present, the extraction of methane from unconventional natural gas is mainly the separation of N2 and CO2. Common separation technologies include condensation separation, hydrate separation, membrane separation and adsorption. Among them, the condensation separation method achieves a higher separation effect by compressing and liquefying the gas and then distilling it. It is one of the commonly used methods in industry, but the separation device is large in size and consumes a lot of energy during operation. The hydrate separation method separates methane by forming hydrates between gas and water under a specific pressure. It has the advantages of simple operation and environmental friendliness, but the separation device also consumes a lot of energy during operation. Membrane separation is one of the commonly used methods in the separation field. It achieves separation through the different permeation rates of methane and nitrogen through the membrane. At present, it is limited by the performance of membrane materials and operating costs, and has not yet been widely used in the field of methane and nitrogen separation. The adsorption method uses the adsorption of adsorbent materials and gases to achieve gas separation. The mechanism can be divided into chemical adsorption and physical adsorption. Among them, physical adsorption relies on the interaction between gas molecules and the adsorbent surface through van der Waals forces and electrostatic forces. In industry, the adsorption and desorption of gases on adsorbents are generally achieved through periodic modulation of pressure or temperature. The separation method is simple to operate and has mild conditions, but it has high requirements on the performance of the adsorbent used. The ideal adsorbent should have the advantages of high adsorption capacity and high selectivity. Existing adsorbents mainly include metal organic frameworks, activated carbon and zeolite molecular sieves. Among them, zeolite molecular sieves have a highly ordered crystal structure, a uniform pore structure, good hydrothermal stability and chemical stability, a large specific surface area and pore volume, and show great application potential in gas separation. However, the methane and nitrogen adsorption separation performance of most existing zeolite molecular sieve adsorbents cannot meet the requirements.

[0004] In summary, developing a zeolite molecular sieve with good hydrothermal stability, high methane-nitrogen separation selectivity and simple synthesis method is a key issue that needs to be urgently solved in achieving efficient separation of methane, promoting the full and efficient development of unconventional gas fields, and realizing the clean and efficient utilization of natural gas resources. Summary of the invention

[0005] The object of the present invention is to overcome the above-mentioned defects existing in the prior art, and to provide a metal-doped modified zeolite molecular sieve adsorbent, its preparation method and application, which can realize the preferential adsorption and capture of N2 gas in the CH4 / N2 mixed gas, the preferential adsorption of CO2 gas in the CO2 / CH4 mixed gas, and the simultaneous removal of N2 and CO2 in methane, nitrogen and carbon dioxide; at the same time, it has the advantages of simple synthesis method, strong hydrothermal stability, high selectivity, etc., and can meet the purification of CH4 in unconventional natural gases such as coalbed methane, shale gas and shallow biogas, and can also meet the requirements of nitrogen removal from high-concentration natural gas and CO2 capture and other scenarios.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] A metal-doped modified zeolite molecular sieve adsorbent, comprising a carrier and an active metal component loaded on the carrier; the carrier is a mordenite molecular sieve; the active metal component comprises at least two of Ca, Mg, Ti, Fe, Ni, Co, Cu, Zn, Na and Ag; in the metal-doped modified zeolite molecular sieve adsorbent, the loading amount of the active metal component is 0.1% to 15%.

[0008] Optionally, the specific surface area of the metal-doped modified zeolite molecular sieve adsorbent is 200 m 2 / g to 600 m 2 / g. With the change of the metal modification element and the increase of the loading amount, the specific surface area will show a decreasing phenomenon, and the preferred specific surface area is 200 m 2 / g to 400 m 2 / g.

[0009] Optionally, the pore diameter of the metal-doped modified zeolite molecular sieve adsorbent is 0.3 nm to 0.4 nm; in order to further improve the nitrogen separation selectivity, the preferred pore diameter is 0.3 nm to 0.38 nm.

[0010] Considering the improvement of the selectivity of methane and nitrogen and the cost, preferably, the active metal component comprises at least one of Ca-Mg, Ca-Ti, Ca-Fe, Ca-Cu, Ca-Zn, Ca-Ni, Ca-Ag, Ca-Na, Mg-Ti, Mg-Fe, Mg-Cu, Mg-Zn, Mg-Ni, Mg-Ag, Mg-Na, Ti-Fe, Ti-Cu, Ti-Zn, Ti-Ni, Ti-Ag, Ti-Na, Fe-Cu, Fe-Zn, Fe-Ni, Fe-Ag, Fe-Na, Cu-Zn, Cu-Ni, Cu-Ag, Cu-Na, Zn-Ni, Zn-Ag, Zn-Na, Ni-Ag, Ni-Na and Ag-Na.

[0011] Preferably, the active metal components include at least two of Ca, Mg, Fe, Cu, Zn, and Na.

[0012] Preferably, the active metal components include at least one of Mg-Fe, Mg-Cu, Mg-Zn, Mg-Ni, Mg-Ag, Mg-Na, Ca-Na, Ti-Na, Fe-Na, Cu-Na, Zn-Na, Ni-Na, and Ag-Na.

[0013] Optionally, the active metal components exist in the form of at least one of metal ions for doping, metal atoms, metal nanoclusters, and metal nanoparticles, preferably one of metal ions and metal atoms.

[0014] Optionally, based on the total mass of the total active metal ions, the mass of each metal element in the active metal components accounts for 0.1% to 10% of the total metal mass, preferably 0.5% to 6%.

[0015] Optionally, the silica-alumina ratio of the mordenite molecular sieve is <20, preferably 2.5 to 8.

[0016] The present invention also discloses a preparation method of the metal-doped modified zeolite molecular sieve adsorbent as described above, comprising the following steps:

[0017] (1) Mix a silicon source, a hydrolysis agent, and deionized water, then add a metal ion precursor MI and a small molecule organic template agent and mix at room temperature for 10 h to 24 h (preferably 10 h to 15 h) to obtain solution A; mix an aluminum source and sodium hydroxide with deionized water at room temperature for 2 h to 24 h (preferably 2 h to 6 h) to obtain solution B; mix solution A and solution B at room temperature for 8 h to 20 h (preferably 10 h to 12 h) to obtain a slurry mixture, and the molar ratio in the slurry mixture is 1SiO2 / 0.35 - 0.75Na2O / 0.05 - 0.3Al2O3 / 0.1 - 0.4template agent / 0 - 0.05MI / 25 - 40H2O; transfer the slurry mixture into a high-pressure reactor, seal it, and crystallize at 150 °C to 200 °C for 24 h to 120 h. After the reaction, filter, wash, and dry the obtained white crystals to obtain a metal-doped molecular sieve.

[0018] (2) Mix a metal ion precursor MII solution and the metal-doped molecular sieve in a ratio of (10 - 60):1, exchange at 30 °C to 80 °C for 1 h to 4 h, filter and wash, then dry at 80 °C to 120 °C for 2 h to 12 h to obtain a secondary metal ion-modified molecular sieve, and then calcine at 350 °C to 650 °C for 1 h to 6 h to obtain the metal-doped modified zeolite molecular sieve adsorbent.

[0019] Optionally, in step (1), the crystallization time is 48 h to 120 h, preferably 60 h to 90 h.

[0020] Optionally, in step (1), the silicon source includes at least one of fumed silica, sodium silicate, tetraethyl orthosilicate, tetrabutyl orthosilicate, methylsilane, and silica sol; preferably, the silicon source includes at least one of tetraethyl orthosilicate, tetrabutyl orthosilicate, methylsilane, and silica sol.

[0021] Optionally, in step (1), the hydrolyzing agent includes at least one of hydrochloric acid, sulfuric acid, nitric acid, formic acid, acetic acid, sodium hydroxide, potassium hydroxide, sodium bicarbonate, potassium bicarbonate, sodium carbonate, and potassium carbonate; preferably, the hydrolyzing agent includes at least one of hydrochloric acid, sulfuric acid, nitric acid, potassium hydroxide, potassium bicarbonate, and potassium carbonate.

[0022] Optionally, for the addition amount of the hydrolyzing agent, the acidic hydrolyzing agent adjusts the pH value of solution A to 0.1 to 4, and the basic hydrolyzing agent adjusts the pH value of solution A to 10 to 13.

[0023] Optionally, in step (1), the aluminum source includes at least one of aluminum sulfate, aluminum chloride, aluminum nitrate, aluminum acetate, aluminum hydroxide, sodium metaaluminate, aluminum isopropoxide, and pseudo-boehmite; preferably, the aluminum source includes at least one of aluminum sulfate, aluminum chloride, aluminum acetate, sodium metaaluminate, and aluminum isopropoxide.

[0024] Optionally, in step (1), the template agent includes at least one of glycerol, ethylene glycol, polyethylene glycol, isopropanol, ethanol, ether, ethyl acetate, ethylene oxide, pyrrolidine, piperazine, piperidine, imidazole, and pyrazole; preferably, the template agent includes at least one of glycerol, ethylene glycol, ethanol, ether, isopropanol, pyrrolidine, and piperazine.

[0025] Optionally, the metal ion precursor MI and the metal ion precursor MII respectively include one or more of monovalent, divalent, trivalent, and tetravalent salts such as Ca, Mg, Ti, Fe, Ni, Co, Cu, Zn, Na, and Ag, preferably at least one of the chlorides, sulfates, nitrates, formates, and acetates of the corresponding metal elements; more preferably at least one of ferric chloride, ferric sulfate, ferric nitrate, ferric formate, ferric acetate, magnesium chloride, magnesium sulfate, magnesium nitrate, magnesium formate, magnesium acetate, manganese chloride, manganese sulfate, manganese nitrate, manganese formate, manganese acetate, zinc chloride, zinc sulfate, zinc nitrate, zinc formate, zinc acetate, copper chloride, copper sulfate, copper nitrate, copper formate, or copper acetate.

[0026] Optionally, the molar ratio of the metal ion precursor MI to the silicon source (calculated as SiO2) is (0 to 0.03):1. It has been found that the loading of the modified metal in the molecular sieve is not directly proportional to the gas adsorption performance. Excessive metal loading will lead to a decrease in adsorption performance. On the one hand, this is because excessive metal species occupy the adsorption sites, resulting in the blocking of active sites. On the other hand, it is because excessive metal species change the surface charge distribution of the molecular sieve.

[0027] Optionally, in step (1), the drying temperature is 100°C to 150°C; the drying time is 6 h to 12 h.

[0028] Optionally, in step (2), the concentration of the metal ion precursor MII solution is 0.05 mol / L to 0.5 mol / L.

[0029] The present invention also discloses an application of the metal-doped modified zeolite molecular sieve adsorbent as described above. The metal-doped modified zeolite molecular sieve adsorbent realizes the separation process of gas mixtures of different gas components.

[0030] Optionally, the metal-doped modified zeolite molecular sieve adsorbent is applied to the mixed gas separation systems of CH4 / CO2, CH4 / N2, CO2 / N2, and CH4 / CO2 / N2.

[0031] Optionally, at normal temperature and pressure, the equilibrium adsorption selectivity of nitrogen to methane > 15, the equilibrium adsorption selectivity of CO2 to methane > 500, and the nitrogen adsorption capacity is greater than 0.4 mmol / g; preferably, the equilibrium adsorption selectivity of nitrogen to methane is 20 to 100, the equilibrium adsorption selectivity of CO2 to methane is 800 to 25000, and the nitrogen adsorption capacity is 0.5 mmol / g to 1.0 mmol / g; more preferably, the equilibrium adsorption selectivity of nitrogen to methane is 40 to 80, the equilibrium adsorption selectivity of CO2 to methane is 1000 to 15000, and the nitrogen adsorption capacity is 0.6 mmol / g to 1.0 mmol / g. With the increase in separation selectivity, the separation ability of nitrogen and carbon dioxide increases, but it may lead to a decrease in their diffusion rate. Those skilled in the art can adjust it according to the needs.

[0032] Optionally, the metal-doped modified zeolite molecular sieve adsorbent of the present invention is applicable to the CH4 / CO2 / N2 separation process in unconventional natural gas. The sources of the unconventional natural gas include, but are not limited to, coalbed methane, shale gas, dissolved gas, and natural gas hydrates.

[0033] Optionally, the metal-doped modified zeolite molecular sieve adsorbent of the present invention preferentially adsorbs N2 during the separation of CH4 / N2 mixed gas, preferentially adsorbs CO2 during the separation of CH4 / CO2 mixed gas, and preferentially adsorbs nitrogen and carbon dioxide during the separation of CH4 / CO2 / N2 mixed gas.

[0034] Implementing the embodiments of the present invention will have the following beneficial effects:

[0035] 1. The metal-doped modified zeolite molecular sieve adsorbent provided by the present invention uses the hydrothermal method to obtain a metal-doped modified molecular sieve with excellent pore structure and adsorption performance, and optimizes the performance through secondary ion exchange to prepare a metal-doped modified zeolite molecular sieve adsorbent with preferential nitrogen adsorption.

[0036] 2. The metal-doped modified zeolite molecular sieve adsorbent provided by the present invention has extremely excellent methane separation and purification performance. At normal temperature and pressure, the equilibrium adsorption selectivity of nitrogen to methane is between 40 and 80, the equilibrium adsorption selectivity of CO2 to methane is between 1000 and 15000, and the nitrogen adsorption capacity is 0.6 mmol / g to 1.0 mmol / g, and those skilled in the art can adjust it according to needs. Description of the Drawings

[0037] Figure 1 It is a schematic diagram of the test results of the adsorption and separation performance of the metal-doped modified zeolite molecular sieve adsorbent in Example 1 of the present invention for CO2, N2, and CH4 at 298K and 1 bar;

[0038] Figure 2 It is the XRD pattern of the transition metal-doped molecular sieve in the examples and comparative examples of the present invention. Detailed Embodiments

[0039] The following further illustrates the present invention with specific embodiments, but does not limit the present invention in any way.

[0040] Unless otherwise specified, the raw materials in the embodiments of the present invention are all purchased through commercial channels.

[0041] The analysis methods in the embodiments of the present invention are as follows:

[0042] The specific surface area and pore parameters are measured by the physical adsorption method, and the specific surface area and pore parameters of the prepared metal-doped modified molecular sieve are calculated from the CO2 adsorption isotherm at 273K. Before the test, the sample is activated under vacuum (<10 -3 Pa) at a temperature of 300°C for more than 4 hours, and the adsorption pressure is 0 - 760 mmHg.

[0043] Static adsorption tests were carried out using the physical adsorption method. The test gases were CO2, CH4, and N2. Their adsorption isotherms were measured at 298 K, and the adsorption pressure was 0 - 1 bar. Before the test, the sample was activated under vacuum (<10 -6 Pa) at a temperature of 300 °C for more than 4 h.

[0044] Example 1

[0045] (1) Preparation of metal-doped zeolite by hydrothermal reaction method: 15 g of silica sol (SiO2 40 wt%) was added to 16 g of deionized water, and KOH was added to adjust the pH value of the solution to 12. After stirring and dispersing evenly, 0.24 g of zinc sulfate as the metal ion precursor was added, and 0.60 g of isopropanol was added. The mixture was stirred at room temperature for 12 h to obtain solution A. 1.16 g of aluminum sulfate and 2.40 g of sodium hydroxide were added to 14 g of deionized water, stirred and dispersed evenly, and stirred at room temperature for 12 h to form solution B. Solution A and solution B were fully mixed and stirred at room temperature for 10 h to obtain a slurry mixture. The molar ratio of the mixed slurry was 1SiO2 / 0.6Na2O / 0.068Al2O3 / 0.2 template agent / 0.03MI / 34H2O. The slurry mixture was transferred to a high-pressure reactor and sealed, and the temperature was raised for crystallization under stirring conditions. The crystallization temperature was 180 °C, and the crystallization time was 72 h. After the reaction, the obtained white crystals were filtered and washed, and dried at 110 °C for 6 h to obtain the metal-doped zeolite;

[0046] (2) Secondary ion exchange modification: The magnesium nitrate solution and the metal-doped zeolite synthesized in step (1) were exchanged in a 0.2 mol / L magnesium nitrate solution at a weight ratio of 20:1 for 2 h at an exchange temperature of 45 °C. After filtration and washing, it was dried at 110 °C for 6 h to obtain the secondary metal ion-modified Zn-Mg zeolite, and then calcined at 550 °C for 2 h to obtain the nitrogen-methane adsorption separation material Zeo-1.

[0047] Example 2

[0048] (1) Preparation of metal-doped molecular sieves by hydrothermal reaction: 2.31 g of methylsilane was added to 20 g of deionized water, nitric acid was added to adjust the pH value of the solution to 3, and the mixture was stirred and dispersed uniformly, then 0.24 g of nickel chloride hexahydrate as a metal ion precursor was added, 1.29 g of piperazine was added, and the mixture was stirred at room temperature for 10 h to obtain solution A. 0.47 g of aluminum chloride and 1.60 g of sodium hydroxide were added to 16 g of deionized water, stirred and dispersed uniformly, and stirred at room temperature for 12 h to form solution B. The solution A and the solution B are fully mixed, and stirred at room temperature for 10 hours to obtain a slurry mixture, wherein the molar ratio of the mixed slurry is 1SiO2 / 0.4Na2O / 0.071Al2O3 / 0.3 template / 0.02MI / 40H2O; the slurry mixture is transferred into a high-pressure reactor and sealed, and the temperature is increased for crystallization under stirring conditions, the crystallization temperature is 200°C, and the crystallization time is 48 hours; after the reaction is completed, the obtained white crystals are filtered and washed, and dried at 150°C for 8 hours to obtain a metal-doped molecular sieve;

[0049] (2) Secondary ion exchange modification: The magnesium nitrate solution and the metal-doped molecular sieve synthesized in step (1) are exchanged in a 0.2 mol / L magnesium nitrate solution at a weight ratio of 25:1 for 2 hours at an exchange temperature of 45°C; after filtering and washing, the mixture is dried at 110°C for 6 hours to obtain a secondary metal ion modified Ni-Mg molecular sieve, which is then calcined at 550°C for 2 hours to obtain a nitrogen-methane adsorption separation material Zeo-2.

[0050] Example 3

[0051] (1) Preparation of metal-doped molecular sieves by hydrothermal reaction: 9.01 g of fumed silica was added to 50 g of deionized water, KOH was added to adjust the pH value of the solution to 13, and the mixture was stirred and dispersed uniformly, and then 0.77 g of copper chloride dihydrate as a metal ion precursor was added, and 1.53 g of imidazole was added, and the mixture was stirred at room temperature for 16 h to obtain solution A. 6.49 g of aluminum acetate dihydrate and 4.80 g of sodium hydroxide were added to 40 g of deionized water, and the mixture was stirred and dispersed uniformly, and stirred at room temperature for 12 h to form solution B. The solution A and the solution B were fully mixed, and stirred at room temperature for 12 hours to obtain a slurry mixture, wherein the molar ratio of the mixed slurry was 1SiO2 / 0.4Na2O / 0.106Al2O3 / 0.15template / 0.03MI / 30H2O; the slurry mixture was transferred into a high-pressure reactor and sealed, and the temperature was raised for crystallization under stirring conditions, the crystallization temperature was 150°C, and the crystallization time was 36 hours; after the reaction was completed, the obtained white crystals were filtered and washed, and dried at 110°C for 6 hours to obtain a metal-doped molecular sieve;

[0052] (2) Secondary ion exchange modification: According to the weight ratio of magnesium nitrate solution to the metal-doped molecular sieve synthesized in step (1) of 20:1, exchange in 0.15 mol / L magnesium nitrate solution for 2 h, and the exchange temperature is 45 °C; after filtration and washing, dry at 110 °C for 12 h to obtain a secondary metal ion-modified Cu-Mg molecular sieve, and then calcine at 550 °C for 2 h to obtain the nitrogen-methane adsorption separation material Zeo-3.

[0053] Examples 4-6

[0054] Compared with Example 1, Examples 4-6 are different in that: the loading amount of each metal element in the active metal component is changed. The method is to change the amount of metal ion precursor added in step (1) to make the MI / SiO2 ratio 0.01, 0.02, 0.05, obtaining the nitrogen-methane adsorption separation materials Zeo-4, Zeo-5, Zeo-6. Except for the above differences, other operations are the same and will not be elaborated here.

[0055] Examples 7-9

[0056] Compared with Example 1, Examples 7-9 are different in that: the loading amount of each metal element in the active metal component is changed. The method is to change the amount of metal ion precursor added in step (2) to make the mass ratio of metal ion precursor MII solution to the metal-doped molecular sieve 10, 30, 60, obtaining the nitrogen-methane adsorption separation materials Zeo-7, Zeo-8, Zeo-9. Except for the above differences, other operations are the same and will not be elaborated here.

[0057] Examples 10-12

[0058] Compared with Example 1, Examples 10-12 are different in that: the loading amount of each metal element in the active metal component is changed. The method is to change the concentration of metal ion precursor MII in step (2) to make the concentration of metal ion precursor MII 0.05 mol / L, 0.3 mol / L, 0.5 mol / L, obtaining the nitrogen-methane adsorption separation materials Zeo-10, Zeo-11, Zeo-12. Except for the above differences, other operations are the same and will not be elaborated here.

[0059] Examples 13-15

[0060] Compared with Example 1, Examples 13-15 are different in that: the amount of aluminum source added is changed to make the silicon-aluminum ratio 5, 12, 20, obtaining the nitrogen-methane adsorption separation materials Zeo-13, Zeo-14, Zeo-15. Except for the above differences, other operations are the same and will not be elaborated here.

[0061] Examples 16-18

[0062] Examples 16 - 18 are different from Example 1 in that the crystallization temperature is changed to 150 °C, 170 °C, and 200 °C to obtain nitrogen-methane adsorption separation materials Zeo-16, Zeo-17, and Zeo-18. Except for the above differences, other operations are the same and will not be elaborated here.

[0063] Examples 19 - 21

[0064] Examples 19 - 21 are different from Example 1 in that the crystallization time is changed to 48 h, 90 h, and 120 h to obtain nitrogen-methane adsorption separation materials Zeo-19, Zeo-20, and Zeo-21. Except for the above differences, other operations are the same and will not be elaborated here.

[0065] Examples 22 - 24

[0066] Examples 22 - 24 are different from Example 1 in that the exchange temperature is changed to 30 °C, 60 °C, and 80 °C to obtain nitrogen-methane adsorption separation materials Zeo-22, Zeo-23, and Zeo-24. Except for the above differences, other operations are the same and will not be elaborated here.

[0067] Examples 25 - 27

[0068] Examples 25 - 27 are different from Example 1 in that the exchange time is changed to 1 h, 3 h, and 4 h to obtain nitrogen-methane adsorption separation materials Zeo-25, Zeo-26, and Zeo-27. Except for the above differences, other operations are the same and will not be elaborated here.

[0069] Examples 28 - 30

[0070] Examples 28 - 30 are different from Example 1 in that the calcination temperature is changed to 350 °C, 450 °C, and 650 °C to obtain nitrogen-methane adsorption separation materials Zeo-28, Zeo-29, and Zeo-30. Except for the above differences, other operations are the same and will not be elaborated here.

[0071] Comparative Example 1

[0072] 15 g of silica sol (SiO2 40 wt%) was added to 16 g of deionized water, and KOH was added to adjust the pH value of the solution to 12. After stirring and dispersing evenly, 0.24 g of zinc sulfate as the metal ion precursor was added, and 0.60 g of isopropanol was added. The mixture was stirred at room temperature for 12 h to obtain solution A. 1.16 g of aluminum sulfate and 2.40 g of sodium hydroxide were added to 14 g of deionized water, stirred and dispersed evenly, and stirred at room temperature for 12 h to form solution B. Solution A and solution B were fully mixed and stirred at room temperature for 10 h to obtain a slurry mixture. The molar ratio of the mixed slurry was 1SiO2 / 0.6Na2O / 0.068Al2O3 / 0.2 template agent / 0.03MI / 34H2O; the slurry mixture was transferred to a high-pressure reactor and sealed, and the temperature was raised for crystallization under stirring conditions. The crystallization temperature was 180 °C and the crystallization time was 72 h; after the reaction, the obtained white crystals were filtered and washed, dried at 110 °C for 6 h, and then calcined at 550 °C for 2 h to obtain the single-metal-exchanged zeolite Zeo-s.

[0073] Table 1 Test results of Examples 1-4 and Comparative Example 1

[0074]

[0075]

[0076] The above embodiments only represent several implementation manners of the present invention. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of this invention patent shall be subject to the appended claims.

Claims

1. A metal-doped modified zeolite molecular sieve adsorbent, characterized in that, It includes a carrier and an active metal component supported on the carrier; The carrier is a mordenite molecular sieve; The active metal component includes at least two of Ca, Mg, Ti, Fe, Ni, Co, Cu, Zn, Na, and Ag; In the metal-doped modified zeolite molecular sieve adsorbent, the loading amount of the active metal component is 0.1% to 15%.

2. The metal-doped modified zeolite molecular sieve adsorbent according to claim 1, wherein The specific surface area of the metal-doped modified zeolite molecular sieve adsorbent is 200 m 2 / g to 600 m 2 / g, and the pore size is 0.3 nm to 0.4 nm.

3. The metal-doped modified zeolite molecular sieve adsorbent according to claim 1, wherein The active metal component includes at least one of Ca-Mg, Ca-Ti, Ca-Fe, Ca-Cu, Ca-Zn, Ca-Ni, Ca-Ag, Ca-Na, Mg-Ti, Mg-Fe, Mg-Cu, Mg-Zn, Mg-Ni, Mg-Ag, Mg-Na, Ti-Fe, Ti-Cu, Ti-Zn, Ti-Ni, Ti-Ag, Ti-Na, Fe-Cu, Fe-Zn, Fe-Ni, Fe-Ag, Fe-Na, Cu-Zn, Cu-Ni, Cu-Ag, Cu-Na, Zn-Ni, Zn-Ag, Zn-Na, Ni-Ag, Ni-Na, and Ag-Na; Based on the total mass of the total active metal ions, the mass of each metal element in the active metal component accounts for 0.1% to 10% of the total metal mass.

4. The metal-doped modified zeolite molecular sieve adsorbent according to claim 1, wherein The silicon-aluminum ratio of the mordenite molecular sieve is <20.

5. A method for preparing a metal-doped modified zeolite molecular sieve adsorbent according to any one of claims 1-4, characterized in that, It includes the following steps: (1) Mix a silicon source and a hydrolysis agent with deionized water, then add a metal ion precursor MI and a small molecule organic template agent and mix at room temperature for 10 h to 24 h to obtain solution A; mix an aluminum source and sodium hydroxide with deionized water at room temperature for 2 h to 24 h to obtain solution B; mix solution A and solution B at room temperature for 8 h to 20 h to obtain a slurry mixture, and the molar ratio in the slurry mixture is 1SiO2 / 0.35 - 0.75Na2O / 0.05 - 0.3Al2O3 / 0.1 - 0.4 template agent / 0 - 0.05MI / 25 - 40H2O; transfer the slurry mixture into a high-pressure reactor, seal it, and crystallize at 150°C to 200°C for 24 h to 120 h. After the reaction, filter, wash, and dry the obtained white crystals to obtain a metal-doped molecular sieve; (2) Mix a metal ion precursor MII solution and the metal-doped molecular sieve in a volume ratio of (10 - 60):1, exchange at 30°C to 80°C for 1 h to 4 h, filter and wash, then dry at 80°C to 120°C for 2 h to 12 h to obtain a secondary metal ion-modified molecular sieve, and then calcine at 350°C to 650°C for 1 h to 6 h to obtain the metal-doped modified zeolite molecular sieve adsorbent.

6. The preparation method according to claim 5, characterized in that, In step (1), the silicon source includes at least one of fumed silica, sodium silicate, tetraethyl orthosilicate, tetrabutyl orthosilicate, methylsilane, and silica sol; In step (1), the hydrolyzing agent includes at least one of hydrochloric acid, sulfuric acid, nitric acid, formic acid, acetic acid, sodium hydroxide, potassium hydroxide, sodium bicarbonate, potassium bicarbonate, sodium carbonate, and potassium carbonate; for the addition amount of the hydrolyzing agent, the pH value of solution A is adjusted to 0.1 - 4 with an acidic hydrolyzing agent, and the pH value of solution A is adjusted to 10 - 13 with a basic hydrolyzing agent; In step (1), the aluminum source includes at least one of aluminum sulfate, aluminum chloride, aluminum nitrate, aluminum acetate, aluminum hydroxide, sodium aluminate, aluminum isopropoxide, and pseudo - boehmite; In step (1), the templating agent includes at least one of glycerol, ethylene glycol, polyethylene glycol, isopropanol, ethanol, ether, ethyl acetate, ethylene oxide, pyrrolidine, piperazine, piperidine, imidazole, and pyrazole.

7. The preparation method according to claim 5, characterized in that, The metal ion precursors MI and MII respectively include at least one of metal nitrates, sulfates, and chlorides; The molar ratio of the metal ion precursor MI to the silicon source (calculated as SiO2) is (0 - 0.03):

1.

8. The preparation method according to claim 5, characterized in that, In step (1), the drying temperature is 100°C - 150°C; the drying time is 6h - 12h; In step (2), the concentration of the metal ion precursor MII solution is 0.05mol / L - 0.5mol / L.

9. Use of the metal-doped modified zeolite molecular sieve adsorbent according to any one of claims 1-4, characterized in that, The metal - doped modified zeolite molecular sieve adsorbent is used in the separation process of gas mixtures with different gas components.

10. The application according to claim 9, wherein The metal - doped modified zeolite molecular sieve adsorbent is applied to the mixed gas separation systems of CH4 / CO2, CH4 / N2, CO2 / N2, and CH4 / CO2 / N2; Under normal temperature and pressure, the equilibrium adsorption selectivity of nitrogen to methane > 15, the equilibrium adsorption selectivity of CO2 to methane > 500, and the nitrogen adsorption capacity is greater than 0.4 mmol / g.

Images