CN117923511A - Method for synthesizing sodium-free ZSM-5 molecular sieve with high crystallinity by pre-crystallization liquid adding method - Google Patents
Method for synthesizing sodium-free ZSM-5 molecular sieve with high crystallinity by pre-crystallization liquid adding method Download PDFInfo
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- 238000002425 crystallisation Methods 0.000 title claims abstract description 55
- 230000008025 crystallization Effects 0.000 title claims abstract description 55
- 238000000034 method Methods 0.000 title claims abstract description 45
- 239000007788 liquid Substances 0.000 title claims abstract description 42
- 239000002808 molecular sieve Substances 0.000 title claims abstract description 41
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 title claims abstract description 41
- 230000002194 synthesizing effect Effects 0.000 title claims abstract description 19
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 18
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 18
- 239000010703 silicon Substances 0.000 claims abstract description 18
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 16
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 12
- 239000008367 deionised water Substances 0.000 claims abstract description 12
- 229910021641 deionized water Inorganic materials 0.000 claims abstract description 12
- 238000001035 drying Methods 0.000 claims abstract description 10
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 9
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 9
- 238000002156 mixing Methods 0.000 claims abstract description 9
- 238000005406 washing Methods 0.000 claims abstract description 7
- 238000006243 chemical reaction Methods 0.000 claims abstract description 4
- 238000001914 filtration Methods 0.000 claims abstract description 3
- 230000015572 biosynthetic process Effects 0.000 claims description 10
- 238000003786 synthesis reaction Methods 0.000 claims description 10
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 9
- 239000007864 aqueous solution Substances 0.000 claims description 9
- LPSKDVINWQNWFE-UHFFFAOYSA-M tetrapropylazanium;hydroxide Chemical compound [OH-].CCC[N+](CCC)(CCC)CCC LPSKDVINWQNWFE-UHFFFAOYSA-M 0.000 claims description 7
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 claims description 5
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 4
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 claims description 4
- WGTYBPLFGIVFAS-UHFFFAOYSA-M tetramethylammonium hydroxide Chemical compound [OH-].C[N+](C)(C)C WGTYBPLFGIVFAS-UHFFFAOYSA-M 0.000 claims description 4
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 3
- 238000007789 sealing Methods 0.000 claims description 3
- 239000000377 silicon dioxide Substances 0.000 claims description 3
- 235000012239 silicon dioxide Nutrition 0.000 claims description 3
- 239000000443 aerosol Substances 0.000 claims description 2
- 229910052593 corundum Inorganic materials 0.000 claims description 2
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 2
- 229940073455 tetraethylammonium hydroxide Drugs 0.000 claims description 2
- LRGJRHZIDJQFCL-UHFFFAOYSA-M tetraethylazanium;hydroxide Chemical compound [OH-].CC[N+](CC)(CC)CC LRGJRHZIDJQFCL-UHFFFAOYSA-M 0.000 claims description 2
- 229910001845 yogo sapphire Inorganic materials 0.000 claims description 2
- 239000011734 sodium Substances 0.000 abstract description 8
- 229910021536 Zeolite Inorganic materials 0.000 abstract description 7
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 abstract description 7
- 239000010457 zeolite Substances 0.000 abstract description 7
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 abstract description 6
- 229910052708 sodium Inorganic materials 0.000 abstract description 6
- QGZKDVFQNNGYKY-UHFFFAOYSA-O ammonium group Chemical group [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 abstract description 5
- 238000004519 manufacturing process Methods 0.000 abstract description 5
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 abstract description 4
- 239000002994 raw material Substances 0.000 abstract description 4
- 239000010865 sewage Substances 0.000 abstract description 3
- 230000035484 reaction time Effects 0.000 abstract description 2
- 238000001308 synthesis method Methods 0.000 abstract description 2
- 239000012452 mother liquor Substances 0.000 abstract 1
- 239000002699 waste material Substances 0.000 abstract 1
- -1 polytetrafluoroethylene Polymers 0.000 description 16
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 16
- 239000004810 polytetrafluoroethylene Substances 0.000 description 16
- 239000011148 porous material Substances 0.000 description 8
- 239000000243 solution Substances 0.000 description 8
- 238000003756 stirring Methods 0.000 description 8
- 239000000203 mixture Substances 0.000 description 5
- 239000002253 acid Substances 0.000 description 4
- 238000002360 preparation method Methods 0.000 description 4
- 238000002441 X-ray diffraction Methods 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 229910021485 fumed silica Inorganic materials 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000001228 spectrum Methods 0.000 description 3
- 239000013078 crystal Substances 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000005342 ion exchange Methods 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 230000032683 aging Effects 0.000 description 1
- 150000003863 ammonium salts Chemical class 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000012847 fine chemical Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000010899 nucleation Methods 0.000 description 1
- 230000006911 nucleation Effects 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 229910001415 sodium ion Inorganic materials 0.000 description 1
- 239000002351 wastewater Substances 0.000 description 1
Abstract
The invention provides a method for synthesizing a sodium-free ZSM-5 molecular sieve with high crystallinity by a pre-crystallization liquid adding method, which comprises the following steps: a) Mixing a silicon source, an organic template agent and deionized water, and crystallizing to obtain a pre-crystallized liquid; b) Mixing an aluminum source, a silicon source, an organic template agent, deionized water and pre-crystallization liquid, crystallizing, filtering, washing, drying and roasting to obtain the sodium-free ZSM-5 molecular sieve with high crystallinity. The invention adopts the sodium-free synthesis method to prepare the molecular sieve, the post-treatment does not need ammonium exchange, the operation process is simple, the waste liquid production amount is small, and a small amount of pre-crystallization liquid is added into the crystallization mother liquor before crystallization, so that the ZSM-5 molecular sieve with high crystallinity can be obtained. The invention can improve the crystallinity of the product, shorten the reaction time, and the reaction process has no sodium-containing raw material, and the prepared ZSM-5 zeolite molecular sieve has no Na +, does not need to carry out an ammonium exchange process, and reduces the production cost and the emission of ammonia nitrogen sewage.
Description
Technical Field
The invention relates to a method for synthesizing a ZSM-5 molecular sieve of a sodium-free system with high crystallinity, belonging to the technical field of catalyst preparation.
Background
The ZSM-5 molecular sieve is a zeolite molecular sieve with unique three-dimensional pore canal which is synthesized by Mobil company in 1972, the pore canal structure of the zeolite molecular sieve is formed by mutually crossing two pore canals, one pore canal is an elliptic ten-membered ring straight pore canal with the size of 5.4 multiplied by 5.6nm, and the other pore canal is a round ten-membered ring Z-shaped pore canal with the size of 5.2 multiplied by 5.8nm. The ZSM-5 molecular sieve has a unique and uniform cross pore structure, strong selective adsorption performance, good thermal stability and hydrothermal stability and moderate acidity, so that the ZSM-5 molecular sieve is widely applied to the fields of adsorption separation, petrochemical industry, fine chemical industry, environmental protection and the like. Accordingly, ZSM-5 zeolite has been receiving a great deal of attention. Of these, the synthesis of ZSM-5 zeolite is critical, while the synthesis of ZSM-5 zeolite without sodium system is one of the difficulties of research.
The existing ZSM-5 molecular sieve is generally produced under the condition that sodium ions participate in a synthesis system, the synthesized molecular sieve is a sodium type molecular sieve, sodium exchange is needed, the molecular sieve is made into ammonium type ZSM-5, and then the ammonium type ZSM-5 with acid catalytic activity is obtained through roasting. In the ion exchange step, excessive ammonium salt or acid-containing solution is usually used, so that a large amount of high-concentration ammonia nitrogen sewage or acid-containing wastewater can be generated, and the direct discharge has an influence on the environment.
Disclosure of Invention
The invention provides a method for synthesizing a sodium-free ZSM-5 molecular sieve with high crystallinity by a pre-crystallization liquid adding method, which not only can prepare the ZSM-5 molecular sieve with high relative crystallinity without adding any sodium-containing raw material by adding the pre-crystallization liquid, thereby solving the problem of ammonia nitrogen pollution or acid pollution caused by ion exchange.
The invention is realized by the following technical method,
The technical scheme of the invention is as follows:
the invention provides a method for synthesizing a sodium-free ZSM-5 molecular sieve with high crystallinity by a pre-crystallization liquid adding method, which comprises the steps of firstly mixing a silicon source, an organic template agent and deionized water, and crystallizing to obtain a pre-crystallization liquid; then mixing an aluminum source, a silicon source, an organic template agent, deionized water and the pre-crystallization liquid obtained in the step S1, sealing the mixture in a reaction kettle, and dynamically crystallizing the mixture; and then filtering, washing, drying and roasting to obtain the ZSM-5 molecular sieve.
The molar ratio of the silicon source, the organic template agent and the water of the pre-crystallization liquid is (5-8): 1 (90-120), wherein the silicon source is calculated according to oxide SiO 2;
The molar ratio of the silicon source to the aluminum source to the organic template agent to the water is (100-120): 1 (5-10): 1000-1500, wherein the silicon source and the aluminum source are calculated according to oxide SiO 2:Al2O3; the adding amount of the pre-crystallization liquid is 15-25% of the mass of the silicon source in the raw material.
As preferable:
the silicon source is at least one of silica sol and aerosol silicon dioxide.
The aluminum source is at least one of aluminum hydroxide and aluminum oxide.
The organic template agent is at least one of tetramethyl ammonium hydroxide aqueous solution, tetraethyl ammonium hydroxide aqueous solution and tetrapropyl ammonium hydroxide aqueous solution.
The rotation speed of the dynamic crystallization is 15-45 rpm.
The crystallization temperature of the pre-crystallization liquid is 80-100 ℃ and the crystallization time is 8-12h; the crystallization temperature of the ZSM-5 molecular sieve in the synthesis stage is 170-200 ℃ and the crystallization time is 24-48h.
The drying temperature is 65-110 ℃, and the drying time is 8-24h.
The roasting temperature is 500-550 ℃ and the roasting time is 2-6h.
The washing is carried out by adopting deionized water.
According to the technical scheme, crystal nuclei formed in the initial crystallization stage are contained in the pre-crystallization liquid, and the ZSM-5 molecular sieve framework structure is induced to be generated, so that the uniformity of particle distribution in a synthesis system can be ensured, and the crystal grains of a synthesized product are reduced, and the uniformity and the dispersity are better. Therefore, the pre-crystallization liquid is added into the synthesis system, so that the nucleation is induced, the particle size distribution of the product is controlled, the high relative crystallinity of the synthesized sample is ensured, the pre-crystallization liquid can be stored for a long time, and the industrial application standard can be achieved.
The beneficial effects of the invention are as follows: the addition of the pre-crystallization liquid in the synthesis method provided by the invention can improve the crystallinity of the product, shorten the reaction time, and the reaction process does not contain sodium-containing raw materials, and the prepared ZSM-5 zeolite molecular sieve does not contain Na +, does not need to carry out an ammonium exchange process, and reduces the production cost and the emission of ammonia nitrogen sewage. The preparation method of the invention has the advantages of low cost, simple operation, no special production equipment and process requirements and easy mass production.
Drawings
Fig. 1 is an XRD spectrum of sample Z1 synthesized in example 1.
Fig. 2 is an XRD spectrum of sample Z2 synthesized in example 2.
Fig. 3 is an XRD spectrum of sample Z3 synthesized in example 3.
Detailed Description
The present invention will be described in detail with reference to examples, but the present invention is not limited to these examples.
Examples 1 to 3
Example 1
Preparation of a pre-crystallization liquid: 12.49g deionized water and 18.13g 40% tetrapropylammonium hydroxide solution are stirred in a 100mL polytetrafluoroethylene lining kettle for 10min and fully mixed until uniform; and (3) dropwise adding 43.55g of 25% silica sol into the solution under stirring, sufficiently shaking for 1h at room temperature, sealing into a polytetrafluoroethylene lining kettle, and dynamically aging for 10h at 100 ℃ to obtain a pre-crystallization liquid.
Synthesis of ZSM-5: adding 0.29g of aluminum hydroxide, 7.27g of 40% tetrapropylammonium hydroxide aqueous solution and 6.59g of deionized water into a polytetrafluoroethylene lining kettle in 100mL, stirring, and fully mixing until the materials are uniform; 47.52g of 25% silica sol is added dropwise into a polytetrafluoroethylene lining kettle under sufficient stirring and vigorously shaken at room temperature for 1h; 2.59g of the prepared pre-crystallization liquid is added into a polytetrafluoroethylene lining kettle and stirred for 1 hour, and the mixture is sealed into the polytetrafluoroethylene lining kettle for crystallization at 190 ℃ at 35rpm for 46 hours. After cooling, centrifugally washing to neutrality, drying at 100 ℃ for 20h, roasting at 550 ℃ for 3h, and synthesizing the sodium-free ZSM-5 molecular sieve with high crystallinity, namely Z1. The relative crystallinity of Z1 was determined to be as high as 114%. The XRD pattern of the sample is shown in FIG. 1.
Example 2
Preparation of a pre-crystallization liquid: 43.03g of deionized water and 17.28g of 40% tetrapropylammonium hydroxide solution are stirred in a 100mL polytetrafluoroethylene lining kettle for 10min and are fully mixed until being uniform; 10.4g of fumed silica is added into the solution under stirring, after the solution is fully vibrated for 1h at room temperature, the solution is sealed into a polytetrafluoroethylene lining kettle, and the solution is dynamically aged for 10h at 100 ℃ to obtain a pre-crystallization liquid.
Synthesis of ZSM-5: adding 0.32g of aluminum hydroxide, 9.07g of 40% tetrapropylammonium hydroxide aqueous solution and 39.6g of deionized water into a polytetrafluoroethylene lining kettle in 100mL, stirring, and fully mixing until the materials are uniform; 13.23g of fumed silica is added into a polytetrafluoroethylene lining kettle under sufficient stirring and vigorously shaken at room temperature for 1h; 2.73g of the prepared pre-crystallization liquid is added into a polytetrafluoroethylene lining kettle and stirred for 1 hour, and the mixture is sealed into the polytetrafluoroethylene lining kettle for crystallization at 190 ℃ at 30rpm for 24 hours. After cooling, centrifugally washing to neutrality, drying at 100 ℃ for 20h, roasting at 550 ℃ for 3h, and synthesizing the sodium-free ZSM-5 molecular sieve with high crystallinity, namely Z2. The relative crystallinity of Z2 was determined to be as high as 112%. The XRD pattern of the sample is shown in FIG. 2.
Example 3
A pre-crystallization liquid was prepared as in example 2.
Synthesis of ZSM-5: stirring 0.32g of aluminum hydroxide, 9.07g of 40% tetrapropylammonium hydroxide aqueous solution and 36.00g of deionized water in a 100mL polytetrafluoroethylene lining kettle, and fully mixing until uniform; 12.02g of fumed silica is added into a polytetrafluoroethylene lining kettle under sufficient stirring and is vigorously shaken for 1h at room temperature; 2.73g of the prepared pre-crystallization liquid is added into a polytetrafluoroethylene lining kettle and stirred for 1 hour, and the mixture is sealed into the polytetrafluoroethylene lining kettle for crystallization at 190 ℃ at 30rpm for 46 hours. After cooling, centrifugally washing to neutrality, drying at 100 ℃ for 20h, roasting at 550 ℃ for 3h, and synthesizing the sodium-free ZSM-5 molecular sieve with high crystallinity, namely Z3. The relative crystallinity of Z3 was determined to be as high as 96%. The XRD pattern of the sample is shown in FIG. 3.
TABLE 1 summary of XRF mass percent of ZSM-5 molecular sieves synthesized in examples 1-3
As can be seen from Table 1, sodium-free ZSM-5 molecular sieve samples with high silica-alumina ratio can be synthesized according to an experimental method, and the feasibility of an experimental scheme is proved.
The present application has been described in terms of embodiments, and it will be appreciated by those of skill in the art that various changes can be made to the features and embodiments, or equivalents can be substituted, without departing from the spirit and scope of the application. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the application without departing from the essential scope thereof. Therefore, it is intended that the application not be limited to the particular embodiment disclosed, but that the application will include all embodiments falling within the scope of the appended claims.
Claims (10)
1. The method for synthesizing the sodium-free ZSM-5 molecular sieve with high crystallinity by using the pre-crystallization liquid adding method is characterized by comprising the following steps of:
S1, mixing a silicon source, an organic template agent and deionized water, and crystallizing to obtain a pre-crystallized liquid;
S2, mixing an aluminum source, a silicon source, an organic template agent, deionized water and the pre-crystallization liquid obtained in the step S1, sealing in a reaction kettle, and dynamically crystallizing;
s3, filtering, washing, drying and roasting the crystallized product in the S2 to obtain the sodium-free ZSM-5 molecular sieve with high crystallinity.
2. The method for synthesizing the sodium-free ZSM-5 molecular sieve with high crystallinity by using the pre-crystallization liquid addition method according to claim 1, wherein the method is characterized in that: the molar ratio of the silicon source of the pre-crystallization liquid, the organic template agent and the water in the S1 is (5-8): 1 (90-120), wherein the silicon source is calculated according to oxide SiO 2.
3. The method for synthesizing the sodium-free ZSM-5 molecular sieve with high crystallinity by using the pre-crystallization liquid addition method according to claim 1, wherein the method is characterized in that: the molar ratio of the silicon source to the aluminum source to the organic template agent to the water in the S2 is (100-120): 1 (5-10): 1000-1500, wherein the silicon source and the aluminum source are calculated according to oxide SiO 2:Al2O3, and the adding amount of the pre-crystallization liquid is 15-25% of the mass of silicon dioxide in the silicon source of the S2.
4. The method for synthesizing the sodium-free ZSM-5 molecular sieve with high crystallinity by using the pre-crystallization liquid addition method according to claim 1, wherein the method is characterized in that: the silicon source is at least one of silica sol and aerosol silicon dioxide.
5. The method for synthesizing the sodium-free ZSM-5 molecular sieve with high crystallinity by using the pre-crystallization liquid addition method according to claim 1, wherein the method is characterized in that: the aluminum source is at least one of aluminum hydroxide and aluminum oxide.
6. The method for synthesizing the sodium-free ZSM-5 molecular sieve with high crystallinity by using the pre-crystallization liquid addition method according to claim 1, wherein the method is characterized in that: the organic template agent is at least one of tetramethyl ammonium hydroxide aqueous solution, tetraethyl ammonium hydroxide aqueous solution or tetrapropyl ammonium hydroxide aqueous solution.
7. The method for synthesizing the sodium-free ZSM-5 molecular sieve with high crystallinity by using the pre-crystallization liquid addition method according to claim 1, wherein the method is characterized in that: the rotation speed of the dynamic crystallization is 15-45 rpm.
8. The method for synthesizing the sodium-free ZSM-5 molecular sieve with high crystallinity by using the pre-crystallization liquid addition method according to claim 1, wherein the method is characterized in that: the crystallization temperature of the pre-crystallization liquid is 80-100 ℃ and the crystallization time is 8-12h; the crystallization temperature of the ZSM-5 molecular sieve in the synthesis stage is 170-200 ℃ and the crystallization time is 24-48h.
9. The method for synthesizing the sodium-free ZSM-5 molecular sieve with high crystallinity by using the pre-crystallization liquid addition method according to claim 1, wherein the method is characterized in that: the drying temperature is 65-110 ℃ and the drying time is 8-24h.
10. The method for synthesizing the sodium-free ZSM-5 molecular sieve with high crystallinity by using the pre-crystallization liquid addition method according to claim 1, wherein the method is characterized in that: the roasting temperature is 500-550 ℃ and the roasting time is 2-6h.
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