CN117430130A - Modified SAPO-56 zeolite molecular sieve, and preparation method and application thereof - Google Patents

Modified SAPO-56 zeolite molecular sieve, and preparation method and application thereof Download PDF

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CN117430130A
CN117430130A CN202311387289.2A CN202311387289A CN117430130A CN 117430130 A CN117430130 A CN 117430130A CN 202311387289 A CN202311387289 A CN 202311387289A CN 117430130 A CN117430130 A CN 117430130A
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sapo
molecular sieve
zeolite molecular
modified
aluminum
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宋晓伟
王超然
李仁浩
梁志强
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Jilin University
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    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B39/00—Compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites; Their preparation; After-treatment, e.g. ion-exchange or dealumination
    • C01B39/54—Phosphates, e.g. APO or SAPO compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
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    • C01B21/00—Nitrogen; Compounds thereof
    • C01B21/04—Purification or separation of nitrogen
    • C01B21/0405—Purification or separation processes
    • C01B21/0433—Physical processing only
    • C01B21/045—Physical processing only by adsorption in solids
    • C01B21/0455—Physical processing only by adsorption in solids characterised by the adsorbent
    • C01B21/0466—Zeolites
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    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B37/00—Compounds having molecular sieve properties but not having base-exchange properties
    • C01B37/06—Aluminophosphates containing other elements, e.g. metals, boron
    • C01B37/08—Silicoaluminophosphates [SAPO compounds], e.g. CoSAPO
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    • C01B2210/0051—Carbon dioxide
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Abstract

The invention provides a modified SAPO-56 zeolite molecular sieve, a preparation method and application thereof, and relates to the technical field of chemical adsorbents. Mixing a silicon source, an aluminum source, phosphoric acid, a template agent and water to obtain initial reaction gel; crystallizing the initial reaction gel to obtain an SAPO-56 type zeolite molecular sieve, wherein the SAPO-56 type zeolite molecular sieve contains a template agent; mixing the SAPO-56 zeolite molecular sieve with a cation solution for ion exchange, and roasting the obtained ion exchange product to obtain a modified SAPO-56 zeolite molecular sieve; the cations in the cation solution include alkali metal ions or lanthanide rare earth metal ions. Modified SAPO-56 zeolite prepared by the inventionThe molecular sieve has high crystallinity, compared with the SAPO-56 molecular sieve raw powder, for CO 2 Has obviously improved adsorption performance and shows excellent CO 2 /N 2 Gas adsorption separation performance.

Description

Modified SAPO-56 zeolite molecular sieve, and preparation method and application thereof
Technical Field
The invention relates to the technical field of chemical adsorbents, in particular to a modified SAPO-56 zeolite molecular sieve, a preparation method and application thereof.
Background
SAPO-56 molecular sieve with AFX framework structure has potential application in gas adsorption separation and some catalytic reactions due to its unique cage structure and proper pore size.
For SAPO-56, the Moises study reported good CO for it 2 Adsorption performance of CO with higher 2 Cycloaddition catalytic activity (Dalton trans.2013, 42, 6732). Niklas studies reported that SAPO-56 synthesized using seed crystals had a carbon dioxide adsorption capacity of 4.73mmol/g and a methane adsorption capacity of 1.08mmol/g at 273K (Inorganica Chimica acta.2021, 525, 120443). Furthermore, niklas et al in another report propose CO of SAPO-56 2 And CH (CH) 4 The adsorption separation selectivity of (a) is 20-30 (appl. Energy.2016, 162, 613-621) (Micropor mesogen mate. 2012, 156, 90-96).
The main component of the industrial flue gas is N 2 And CO 2 . In the adsorption separation technology of industrial flue gas, the adsorption separation technology is realized by using N 2 In selective adsorption of CO 2 Is always a hot spot and a difficult problem of research, while SAPO molecular sieves are used for CO 2 The adsorption capacity of (2) is generally low and the separation effect on flue gas is poor.
Disclosure of Invention
In view of the above, the invention aims to provide a modified SAPO-56 zeolite molecular sieve, and a preparation method and application thereof. The modified SAPO-56 zeolite molecular sieve prepared by the invention has high crystallization degree and excellent CO 2 /N 2 Gas adsorption separation performance.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a preparation method of a modified SAPO-56 zeolite molecular sieve, which comprises the following steps:
mixing a silicon source, an aluminum source, phosphoric acid, a template agent and water to obtain initial reaction gel; the template agent is N, N, N ', N' -tetramethyl-1, 6-hexamethylenediamine;
crystallizing the initial reaction gel to obtain an SAPO-56 type zeolite molecular sieve, wherein the SAPO-56 type zeolite molecular sieve contains a template agent;
mixing the SAPO-56 zeolite molecular sieve with a cation solution for ion exchange, and roasting the obtained ion exchange product to obtain a modified SAPO-56 zeolite molecular sieve; the cations in the cation solution include alkali metal ions or lanthanide rare earth metal ions.
Preferably, the silicon source comprises one or more of silica sol, sodium silicate, potassium silicate and white carbon black; the aluminum source comprises one or more of aluminum hydroxide, aluminum oxide, aluminum chloride, aluminum sulfate, sodium aluminate, pseudo-boehmite, aluminum isopropoxide and gibbsite.
Preferably, the silicon source, aluminum source and phosphoric acid are each in the form of SiO 2 、Al 2 O 3 And P 2 O 5 The molar ratio of the silicon source to the aluminum source to the phosphoric acid to the template agent to the water is (0.2-1): 0.5-1): 0.37: (2-3): (20-100).
Preferably, the crystallization temperature is 150-220 ℃ and the time is 2-6 days.
Preferably, the alkali metal ion comprises Li + 、Na + 、K + And Cs + One or more of the lanthanide rare earth metal ions comprise La 3+ 、Ce 3+ And Sm 3+ One or more of them.
Preferably, the concentration of the cation solution is 0.2-1.0 mol/L, and the ratio of the mass of the SAPO-56 type zeolite molecular sieve to the volume of the cation solution is 1g: (40-80) mL.
Preferably, the temperature of the ion exchange is 40-80 ℃ and the time is 3-8 h; the roasting temperature is 400-800 ℃ and the roasting time is 3-10 h.
The invention provides the modified SAPO-56 zeolite molecular sieve prepared by the preparation method according to the technical scheme, wherein the modified SAPO-56 zeolite molecular sieve is an alkali metal ion modified SAPO-56 zeolite molecular sieve or a lanthanide rare earth metal ion modified SAPO-56 zeolite molecular sieve.
The invention provides application of the modified SAPO-56 zeolite molecular sieve in selective adsorption of carbon dioxide.
Preferably, the selective adsorption comprises selectively adsorbing carbon dioxide from a mixed gas comprising nitrogen and carbon dioxide.
The invention provides a preparation method of a modified SAPO-56 zeolite molecular sieve, which comprises the following steps: mixing a silicon source, an aluminum source, phosphoric acid, a template agent and water to obtain initial reaction gel; the template agent is N, N, N ', N' -tetramethyl-1, 6-hexamethylenediamine; crystallizing the initial reaction gel to obtain an SAPO-56 type zeolite molecular sieve, wherein the SAPO-56 type zeolite molecular sieve contains a template agent; mixing the SAPO-56 zeolite molecular sieve with a cation solution for ion exchange, and roasting the obtained ion exchange product to obtain a modified SAPO-56 zeolite molecular sieve; the cations in the cation solution include alkali metal ions or lanthanide rare earth metal ions. In the prior art, the molecular sieve is modified, usually, the template agent is removed firstly and then ion exchange is carried out, the collapse of a molecular sieve skeleton structure is easily caused by the method, the SAPO-56 zeolite molecular sieve is firstly ion exchanged and then the template agent is removed, and the SAPO-56 zeolite molecular sieve subjected to metal cation exchange maintains good crystal structure stability, so that the obtained modified SAPO-56 zeolite molecular sieve maintains higher crystallization degree, and can maintain stable strength and adsorption performance in gas adsorption; the invention adopts alkali metal ion or lanthanide rare earth ion to exchange ions for SAPO-56 zeolite molecular sieve, and uses alkali metal ion or lanthanide rare earth ion to replace hydrogen ion as balance charge, thereby resulting in strong electric field intensity inside zeolite, compared with SAPO-56 molecular sieve raw powder, the invention has high polarizability for CO 2 Has obviously improved adsorption performance and shows excellent CO 2 /N 2 Gas adsorption separation performance.
Example results show that when the cation is an alkali metal ion, the resulting modified SAP O-56 zeolite molecular sieve is resistant to CO at 298K 2 Saturated adsorption capacity of 0.45-3.83 mmol/g (1 bar, 298K), CO 2 -N 2 The separation coefficient is 88-1594 (0.15 bar/0.85bar, 298K); when the cation is lanthanide rare earth metal ion, the preparation methodModified SAPO-56 zeolite molecular sieve to CO 2 Saturated adsorption capacity of 3.56-4.30 mmol/g (1 bar, 298K), CO 2 -N 2 The separation coefficient was 894 to 994 (0.15 bar/0.85bar, 298K).
Drawings
FIG. 1 is a schematic diagram of M-SAPO-56 (M=Li) prepared in example 1 + ，Na + ，K + ，Cs + ) Type molecular sieves and M-SAPO-56-C prepared in comparative example 1 (m=li + ，Na + ，K + ，Cs + ) XRD pattern of (b);
FIG. 2 is an SEM image of the M-SAPO-56 type molecular sieve prepared in example 1, and (a) to (d) in FIG. 2 correspond to Li-SAPO-56, na-SAPO-56, K-SAPO-56 and Cs-SAPO-56 in order;
FIG. 3 is a schematic diagram of Ln-SAPO-56 (Ln=La) 3+ ，Ce 3+ ，Sm 3+ ) Type zeolite molecular sieve and Ln-SAPO-56-C prepared in comparative example 2 (ln=la) 3+ ，Ce 3+ ，Sm 3+ ) XRD pattern of (b);
FIG. 4 is an SEM image of an Ln-SAPO-56 type zeolite molecular sieve prepared in example 2, and (a) to (c) in FIG. 4 correspond to Sm-SAPO-56, la-SAPO-56 and Ce-SAPO-56 in order;
FIG. 5 is a schematic illustration of M-SAPO-56 prepared in example 1 (M=Li + ，Na + ，K + ，Cs + ) CO at 298K 2 Adsorption isotherms;
FIG. 6 is a schematic diagram of M-SAPO-56 prepared in example 1 (M=Li + ，Na + ，K + ，Cs + ) N at 298K 2 Adsorption isotherms;
FIG. 7 is a schematic diagram of Ln-SAPO-56 (Ln- =La) prepared in example 2 3+ ，Ce 3+ ，Sm 3+ ) CO at 298K of 2 Adsorption isotherms;
FIG. 8 is a schematic diagram of Ln-SAPO-56 prepared in example 2 (Ln=La) 3+ ，Ce 3+ ，Sm 3+ ) N at 298K 2 Adsorption isotherms.
Detailed Description
The invention provides a preparation method of a modified SAPO-56 zeolite molecular sieve, which comprises the following steps:
mixing a silicon source, an aluminum source, phosphoric acid, a template agent and water to obtain initial reaction gel; the template agent is N, N, N ', N' -tetramethyl-1, 6-hexamethylenediamine;
crystallizing the initial reaction gel to obtain an SAPO-56 type zeolite molecular sieve, wherein the SAPO-56 type zeolite molecular sieve contains a template agent;
mixing the SAPO-56 zeolite molecular sieve with a cation solution for ion exchange, and roasting the obtained ion exchange product to obtain a modified SAPO-56 zeolite molecular sieve; the cations in the cation solution include alkali metal ions or lanthanide rare earth metal ions.
In the present invention, unless otherwise specified, all the materials involved are commercially available products well known to those skilled in the art.
According to the invention, a silicon source, an aluminum source, phosphoric acid, a template agent and water are mixed to obtain initial reaction gel. In the invention, the template agent is N, N, N ', N' -tetramethyl-1, 6-hexamethylenediamine. In the present invention, the silicon source preferably includes one or more of silica sol, sodium silicate, potassium silicate and white carbon black, more preferably silica sol or sodium silicate, and the content of silica in the silica sol is preferably 20 to 40wt%, more preferably 40wt%. In the present invention, the aluminum source preferably includes one or more of aluminum hydroxide, aluminum oxide, aluminum chloride, aluminum sulfate, sodium aluminate, pseudo-boehmite, aluminum isopropoxide and gibbsite, more preferably aluminum chloride, sodium aluminate, pseudo-boehmite or aluminum isopropoxide. In the present invention, the phosphoric acid is preferably added in the form of an aqueous phosphoric acid solution, and the mass fraction of the aqueous phosphoric acid solution is preferably 85%.
In the present invention, the silicon source, aluminum source and phosphoric acid are respectively represented by SiO 2 、Al 2 O 3 And P 2 O 5 The molar ratio of the silicon source, the aluminum source, the phosphoric acid, the template agent and the water is preferably (0.2-1): 0.5-1): 0.37: (2-3): (20-100), more preferably (0.2-0.8): (0.5-0.7): (0.37): (2-2.7): (40-100), still more preferably (0.5-0.8): (0.5-0.7): (0.37): (2-2.7): (40-80).
In the present invention, the mixing of the silicon source, the aluminum source, the phosphoric acid, the template agent and the water preferably comprises the steps of:
firstly mixing water and phosphoric acid to obtain a first mixed system;
performing second mixing on the first mixed system and an aluminum source to obtain a second mixed system;
thirdly mixing the second mixed system with a silicon source to obtain a third mixed system;
and fourthly, carrying out fourth mixing on the third mixed system and the template agent to obtain initial reaction gel.
In the invention, phosphoric acid is preferably added into water for first mixing, and the time of the first mixing is not particularly limited, so that the raw materials can be uniformly mixed. The present invention preferably adds the aluminum source to the first mixing system for a second mixing, preferably for a period of 1 hour. The present invention preferably adds the silicon source to the second mixing system for a third mixing, preferably for a period of 2 hours. In the present invention, the first, second and third mixing means are preferably stirring and mixing. The template agent is preferably dripped into a third mixed system, the mixed solution is flocculent when the template agent is dripped, and one drip is dripped after the floccule gradually becomes transparent solution; after the template agent is added dropwise, the obtained mixed system is preferably stirred for 24 hours to obtain initial reaction gel.
After the initial reaction gel is obtained, the initial reaction gel is crystallized to obtain the SAPO-56 type zeolite molecular sieve, wherein the SAPO-56 type zeolite molecular sieve contains a template agent. In the present invention, the crystallization temperature is preferably 150 to 220 ℃, more preferably 160 to 210 ℃, still more preferably 190 to 200 ℃; the crystallization time is preferably 2 to 6 days, more preferably 3 to 6 days, and even more preferably 4 to 5 days. In the present invention, the crystallization means is preferably static crystallization. In an embodiment of the present invention, the static crystallization is preferably performed in an autoclave.
After the crystallization is finished, the solid-liquid separation is preferably carried out on the system obtained after the crystallization, and the obtained solid material is dried to obtain the SAPO-56 type zeolite molecular sieve, wherein the SAPO-56 type zeolite molecular sieve contains a template agent. The solid-liquid separation mode is not particularly limited, and any solid-liquid separation mode known in the art may be adopted, such as suction filtration or centrifugal separation. The method of drying is not particularly limited, and a drying method well known to those skilled in the art may be employed; in the embodiment of the present invention, the drying mode is preferably drying, the drying temperature is preferably 70-130 ℃, more preferably 80 ℃, and the drying time is preferably 12h.
After the SAPO-56 type zeolite molecular sieve is obtained, the SAPO-56 type zeolite molecular sieve is mixed with a cationic solution for ion exchange, and the obtained ion exchange product is roasted to obtain the modified SAPO-56 type zeolite molecular sieve. The invention carries out ion exchange on the molecular sieve on the premise of not removing the template agent. In the present invention, the cations in the cation solution include alkali metal ions, preferably including Li, or lanthanide rare earth metal ions + 、Na + 、K + And Cs + Preferably, the lanthanide rare earth metal ion comprises La 3+ 、Ce 3+ And Sm 3+ One or more of them. In the present invention, the cation in the cation solution is preferably derived from a soluble alkali metal salt, preferably an alkali metal chloride salt or an alkali metal nitrate, such as lithium chloride, lithium nitrate, sodium chloride, sodium nitrate, potassium chloride, potassium nitrate, cesium chloride, cesium nitrate; the soluble rare earth salt is preferably lanthanum chloride or lanthanum nitrate, such as lanthanum chloride, lanthanum nitrate, cerium chloride, cerium nitrate, samarium chloride, samarium nitrate.
In the present invention, the concentration of the cationic solution is preferably 0.2 to 1.0mol/L, more preferably 0.25 to 0.5mol/L; the ratio of the mass of the SAPO-56 type zeolite molecular sieve to the volume of the cationic solution (i.e., solid-to-liquid ratio S/L) is preferably 1g: (40-80) mL, more preferably 1g: (40-60) mL.
In the present invention, the temperature of the ion exchange reaction is preferably 40 to 80 ℃, more preferably 40 to 60 ℃; the time is preferably 3 to 8 hours, more preferablyAnd selecting 4-7 h. In the ion exchange reaction process, the cation exchanges ions of the SAPO-56 type zeolite molecular sieve, so that the cation composition of the SAPO-56 type zeolite molecular sieve and the internal electric field strength of the molecular sieve are changed, and the modified SAPO-56 is subjected to CO 2 The selective adsorption capacity of (2) is greatly improved.
After the ion exchange, the invention preferably carries out solid-liquid separation on the obtained system, and washes and dries the obtained solid material to obtain the ion exchange product. In the present invention, the number of times of the water washing is preferably 3, and the purpose of the water washing is to remove impurities remaining on the surface of the sample; the drying temperature is preferably 80 ℃ and the drying time is preferably 12 hours.
In the present invention, the temperature of the calcination is preferably 400 to 800 ℃, more preferably 550 to 700 ℃; the time is preferably 3 to 10 hours, more preferably 4 to 7 hours. In the present invention, the atmosphere of the firing is preferably an air atmosphere, and the firing is preferably performed in a muffle furnace. In the present invention, the purpose of the calcination is to remove the templating agent N, N, N ', N' -tetramethyl-1, 6-hexanediamine. In the prior art, the molecular sieve is modified, usually by removing the template agent and then carrying out ion exchange, the method is easy to cause collapse of a molecular sieve framework structure, and the SAPO-56 zeolite molecular sieve is subjected to ion exchange and then roasting to remove the template agent for the first time, so that the SAPO-56 after metal cation exchange has good crystal structure stability.
The invention provides the modified SAPO-56 zeolite molecular sieve prepared by the preparation method according to the technical scheme, wherein the modified SAPO-56 zeolite molecular sieve is an alkali metal ion modified SAPO-56 zeolite molecular sieve or a lanthanide rare earth metal ion modified SAPO-56 zeolite molecular sieve. In the embodiment of the invention, the alkali metal ion modified SAPO-56 type zeolite molecular sieve and the lanthanide rare earth ion modified SAPO-56 type zeolite molecular sieve are respectively named as M-SAPO-56 and Ln-SAPO-56 type zeolite molecular sieves. The crystallinity and the morphology of the modified SAPO-56 zeolite molecular sieve provided by the invention are kept good.
The invention provides the application of the modified SAPO-56 zeolite molecular sieve in the technical scheme in the selective adsorption of carbon dioxide, namely the modificationThe sexual SAPO-56 zeolite molecular sieve can be used as a carbon dioxide selective adsorbent. In the present invention, the selective adsorption preferably includes adsorption of a catalyst from a mixed gas (CO) containing nitrogen and carbon dioxide 2 /N 2 =15/85), the mixed gas of nitrogen and carbon dioxide preferably comes from flue gas, and the volume ratio of carbon dioxide and nitrogen in the mixed gas is preferably 15:85.
in the present invention, the modified SAPO-56 zeolite molecular sieve is preferably subjected to an activation treatment under vacuum conditions prior to the application; the temperature of the activation treatment is preferably 200 to 450 ℃, more preferably 300 to 350 ℃, and the time is preferably 8 to 12 hours, more preferably 9 to 10 hours. The invention removes the moisture in the molecular sieve through the activation.
In the present invention, in one aspect, CO 2 (0.33 nm) kinetic diameter smaller than CH 4 (0.38 nm) and N 2 (0.364 nm); on the other hand, CO 2 Is far more polar than N 2 . The modified SAPO-56 zeolite molecular sieve takes alkali metal ions or lanthanide rare earth metal ions instead of hydrogen ions as balance charges, thereby leading to strong electric field intensity inside the zeolite. Compared with the raw powder of the SAPO-56 molecular sieve, the modified SAPO-56 molecular sieve has high-polarizability CO 2 Has obviously improved adsorption performance and shows excellent CO 2 /N 2 Gas adsorption separation performance.
In order to further illustrate the present invention, the modified SAPO-56 zeolite molecular sieves provided herein, as well as methods of making and using the same, are described in detail below with reference to the examples, but are not to be construed as limiting the scope of the present invention.
Example 1
Modified M-SAPO-56 (m=li) + ，Na + ，K + ，Cs + ) The preparation method of the zeolite molecular sieve comprises the following steps:
(1) 2.30g of aqueous phosphoric acid (85 wt%) was added to 27.868g of deionized water and stirred, followed by 2.652g of sodium aluminate in a beaker and stirred for 1h, 2.023g of silica sol (SiO 2 40wt% of the content of the components) and evenly stirring for 2 hours, and then adding dropwiseAdding 11.459g of organic template N, N, N ', N' -tetramethyl-1, 6-hexamethylenediamine, enabling a mixed solution in a beaker to be flocculent when the template is dripped, dripping one drop of the flocculent after the flocculent is gradually changed into a transparent solution, covering a sealing film on the final mixed solution after the flocculent is completely added, and stirring for 24 hours at room temperature to obtain initial reaction gel;
transferring the initial reaction gel into a high-pressure reaction kettle, crystallizing for 4 days at 200 ℃, filtering, and drying the obtained solid material for 12 hours at 80 ℃ to obtain the SAPO-56 zeolite molecular sieve.
(2) The SAPO-56 type zeolite molecular sieve prepared in example 1 and 0.5mol/L LiCl, naCl, KCl, csCl solution are stirred and mixed for 4 hours at 60 ℃ respectively according to the ratio of the mass of the SAPO-56 type zeolite molecular sieve to the volume of the alkali chloride salt solution S/l=1g:50 ml, and then filtered, and the obtained solid material is washed by deionized water and dried for 12 hours at 80 ℃ to obtain an ion exchange product.
(3) The ion exchange product was calcined in a muffle furnace at 550 ℃ for 6 hours to give a modified SAPO-56 type zeolite molecular sieve, designated as M-SAPO-56 (m=li + ，Na + ，K + ，Cs + ) Zeolite molecular sieves.
Comparative example 1
M-SAPO-56-C(M＝Li + ，Na + ，K + ，Cs + ) The preparation method of the zeolite molecular sieve comprises the following steps:
(1) The preparation of the SAPO-56 type zeolite molecular sieve is the same as in example 1;
(2) Placing the SAPO-56 zeolite molecular sieve obtained in the step (1) in a muffle furnace to bake for 6 hours at 550 ℃ to obtain the H-SAPO-56 zeolite molecular sieve;
(3) After ion-exchanging the H-SAPO-56 type molecular sieve according to the exchanging method of the step (2) in the example 1, roasting the molecular sieve according to the roasting method of the step (3) in the example 1 to obtain M-SAPO-56-C (M=Li + ，Na + ，K + ，Cs + ) Zeolite molecular sieves.
FIG. 1 shows M (Li) + 、Na + 、K + 、Cs + ) SAPO-56 type moleculesSieves and M (Li) + 、Na + 、K + 、Cs + ) XRD pattern of SAPO-56-C type molecular sieve. Alkali metal ion (Li) + 、Na + 、K + 、Cs + ) After the method of exchanging before roasting is adopted, the M-SAPO-56 type molecular sieve still maintains the original topological structure, and the crystallinity of the molecular sieve is equal to that of the sample M-SAPO-56-C exchanged after roasting (M=Li + ，Na + ，K + ，Cs + ) (comparative example 1) still remains high compared to the above.
FIG. 2 shows M (Li + 、Na + 、K + 、Cs + ) SEM images of SAPO-56 type molecular sieves. In FIG. 2, (a) to (d) correspond to Li-SAPO-56, na-SAPO-56, K-SAPO-56, cs-SAPO-56 in this order. From FIG. 2, it can be seen that M (Li + 、Na + 、K + 、Cs + ) The SAPO-56 type molecular sieve is hexagonal "pie" in morphology, with no amorphous presence.
Example 2
Ln-SAPO-56(Ln＝La 3+ ，Ce 3+ ，Sm 3+ ) The preparation method of the zeolite molecular sieve comprises the following steps:
(1) The preparation of the SAPO-56 type zeolite molecular sieve is the same as in example 1.
(2) The SAPO-56 zeolite molecular sieve prepared in the step (1) is respectively mixed with 0.25mol/L rare earth metal solution (La 3+ ，Ce 3+ ，Sm 3+ ) Stirring and mixing for 4 hours at 60 ℃, filtering, washing the obtained solid material with deionized water, and drying for 12 hours at 80 ℃ to obtain the ion exchange product.
(3) The ion exchange product was calcined in a muffle furnace at 550 c for 6 hours to give a modified SAPO-56 type zeolite molecular sieve, designated Ln-SAPO-56 (ln=la) 3+ ，Ce 3+ ，Sm 3+ ) Zeolite molecular sieves.
Comparative example 2
Ln-SAPO-56-C(Ln＝La 3+ ，Ce 3+ ，Sm 3+ ) Zeolite molecular sieve and its preparing processThe following are provided:
(1) The preparation of the SAPO-56 type zeolite molecular sieve is the same as in example 1.
(2) And (3) placing the SAPO-56 type zeolite molecular sieve obtained in the step (1) in a muffle furnace, and roasting for 6 hours at 550 ℃ to obtain the H-SAPO-56 type zeolite molecular sieve.
(3) Ion-exchanging the H-SAPO-56 molecular sieve according to the exchanging method of the step (2) in the example 2, and then roasting the molecular sieve according to the roasting method of the step (3) to obtain Ln-SAPO-56-C (Ln=La) 3+ ，Ce 3+ ，Sm 3+ ) Zeolite molecular sieves.
FIG. 3 is a schematic diagram of Ln-SAPO-56 (Ln=La) 3+ ，Ce 3+ ，Sm 3+ ) XRD spectra of zeolite molecular sieves, it can be seen that rare earth lanthanide metal ions (La 3+ ，Ce 3+ ，Sm 3+ ) After exchange, the SAPO-56 type molecular sieve still maintains the original topological structure. Rare earth lanthanide metal ions (La) 3+ ，Ce 3+ ，Sm 3+ ) After the exchange-before-bake process, ln-SAPO-56 (ln=la 3+ ，Ce 3+ ，Sm 3+ ) The molecular sieve still maintains the original topological structure, and the crystallinity of the molecular sieve is equal to that of a sample Ln-SAPO-56-C exchanged after roasting (Ln=La) 3+ ，Ce 3+ ，Sm 3+ ) (comparative example 2) still remains high compared to the above.
FIG. 4 is an SEM image of an Ln-SAPO-56 type zeolite molecular sieve prepared in example 2, and (a) to (c) in FIG. 4 correspond to Sm-SAPO-16, la-SAPO-56, ce-SAPO-56 in order. From FIG. 4, it can be seen that Ln-SAPO-56 (Ln=La 3+ ，Ce 3+ ，Sm 3+ ) The molecular sieve is hexagonal and has a shape of cake, and no amorphous state exists.
Application example
The modified SAPO-56 molecular sieves prepared in example 1 and example 2 were used as raw materials for gas selective adsorption separation tests. Before testing, all zeolite molecular sieves are activated for 10 hours at 350 ℃ under vacuum, after a sample is cooled to room temperature, isothermal adsorption and desorption testing of single-component gas is carried out, the testing temperature is 298K, the testing pressure is 0-1 bar, and the testing result is as follows:
FIG. 5 is a schematic diagram of M-SAPO-56 (M=Li) prepared in example 1 + ，Na + ，K + ，Cs + ) CO at 298K 2 Adsorption isotherms.
FIG. 6 is an illustration of M-SAPO-56 (M=Li) prepared in example 1 + ，Na + ，K + ，Cs + ) N at 298K 2 Adsorption isotherms.
FIG. 7 is a schematic diagram of Ln-SAPO-56 (Ln=La) prepared in example 2 3+ ，Ce 3+ ，Sm 3+ ) CO at 298K of 2 Adsorption isotherms.
FIG. 8 is a schematic diagram of Ln-SAPO-56 (Ln=La) prepared in example 2 3+ ，Ce 3+ ，Sm 3+ ) N at 298K 2 Adsorption isotherms.
Table 1 shows the M-SAPO-56 prepared in examples 1 and 2 (M=Li + ，Na + ，K + ，Cs + ) And Ln-SAPO-56 (ln=la) 3 + ，Ce 3+ ，Sm 3+ ) Separation effect of the zeolite molecular sieve.
Table 1M-SAPO-56 (m=li + ，Na + ，K + ，Cs + ) Type and Ln-SAPO-56 (ln=la) 3+ ，Ce 3+ ，Sm 3+ ) Gas separation effect of zeolite molecular sieves
As can be seen from table 1, the modified zeolite molecular sieve was ion-exchanged to obtain M-SAPO-56 (m=li + ，Na + ，K + ，Cs + ) Zeolite molecular sieves and Ln-SAPO-56 (ln=la) 3+ ，Ce 3+ ，Sm 3+ ) Zeolite molecular sieve pair CO 2 The selective adsorption performance is obviously improved.
The foregoing is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that modifications and adaptations to the present invention may occur to one skilled in the art without departing from the principles of the present invention and are intended to be comprehended within the scope of the present invention.

Claims (10)

1. The preparation method of the modified SAPO-56 zeolite molecular sieve is characterized by comprising the following steps of:
mixing a silicon source, an aluminum source, phosphoric acid, a template agent and water to obtain initial reaction gel; the template agent is N, N, N ', N' -tetramethyl-1, 6-hexamethylenediamine;
crystallizing the initial reaction gel to obtain an SAPO-56 type zeolite molecular sieve, wherein the SAPO-56 type zeolite molecular sieve contains a template agent;
mixing the SAPO-56 zeolite molecular sieve with a cation solution for ion exchange, and roasting the obtained ion exchange product to obtain a modified SAPO-56 zeolite molecular sieve; the cations in the cation solution include alkali metal ions or lanthanide rare earth metal ions.
2. The method of claim 1, wherein the silicon source comprises one or more of silica sol, sodium silicate, potassium silicate, and white carbon black; the aluminum source comprises one or more of aluminum hydroxide, aluminum oxide, aluminum chloride, aluminum sulfate, sodium aluminate, pseudo-boehmite, aluminum isopropoxide and gibbsite.
3. The preparation method according to claim 1 or 2, wherein the silicon source, the aluminum source and the phosphoric acid are each represented by SiO 2 、Al 2 O 3 And P 2 O 5 The molar ratio of the silicon source to the aluminum source to the phosphoric acid to the template agent to the water is (0.2-1): 0.5-1): 0.37: (2-3): (20-100).
4. The method according to claim 1, wherein the crystallization temperature is 150 to 220 ℃ for 2 to 6 days.
5. The method of claim 1, wherein the alkali metal ions comprise Li + 、Na + 、K + And Cs + One or more of the lanthanide rare earth metal ions comprise La 3+ 、Ce 3+ And Sm 3+ One or more of them.
6. The preparation method according to claim 1, wherein the concentration of the cationic solution is 0.2 to 1.0mol/L, and the ratio of the mass of the SAPO-56 type zeolite molecular sieve to the volume of the cationic solution is 1g: (40-80) mL.
7. The preparation method according to claim 1, wherein the ion exchange temperature is 40-80 ℃ for 3-8 hours; the roasting temperature is 400-800 ℃ and the roasting time is 3-10 h.
8. The modified SAPO-56 zeolite molecular sieve prepared by the preparation method of any one of claims 1 to 7, wherein the modified SAPO-56 zeolite molecular sieve is an alkali metal ion modified SAPO-56 zeolite molecular sieve or a lanthanide rare earth ion modified SAPO-56 zeolite molecular sieve.
9. The use of the modified SAPO-56 zeolite molecular sieve as claimed in claim 8, for selective adsorption of carbon dioxide.
10. The use of claim 9, wherein the selective adsorption comprises selective adsorption of carbon dioxide from a mixed gas comprising nitrogen and carbon dioxide.
CN202311387289.2A 2023-10-25 2023-10-25 Modified SAPO-56 zeolite molecular sieve, and preparation method and application thereof Pending CN117430130A (en)

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