CN115784254A - Preparation method of fly ash-based MFI structure nano zeolite rich in mesopores - Google Patents
Preparation method of fly ash-based MFI structure nano zeolite rich in mesopores Download PDFInfo
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- 239000010881 fly ash Substances 0.000 title claims abstract description 124
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 title claims abstract description 91
- 239000010457 zeolite Substances 0.000 title claims abstract description 91
- 229910021536 Zeolite Inorganic materials 0.000 title claims abstract description 90
- 238000002360 preparation method Methods 0.000 title claims abstract description 23
- 238000000034 method Methods 0.000 claims abstract description 19
- 238000003756 stirring Methods 0.000 claims description 63
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical group [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 54
- 238000000227 grinding Methods 0.000 claims description 25
- 238000005406 washing Methods 0.000 claims description 24
- 238000001354 calcination Methods 0.000 claims description 23
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 claims description 22
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 21
- 239000000203 mixture Substances 0.000 claims description 19
- 230000032683 aging Effects 0.000 claims description 18
- 238000002425 crystallisation Methods 0.000 claims description 18
- 230000008025 crystallization Effects 0.000 claims description 18
- 238000006243 chemical reaction Methods 0.000 claims description 17
- 238000001035 drying Methods 0.000 claims description 16
- 238000001816 cooling Methods 0.000 claims description 14
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 13
- 238000002156 mixing Methods 0.000 claims description 12
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 10
- KDXKERNSBIXSRK-UHFFFAOYSA-N Lysine Natural products NCCCCC(N)C(O)=O KDXKERNSBIXSRK-UHFFFAOYSA-N 0.000 claims description 10
- 239000004472 Lysine Substances 0.000 claims description 10
- 229920000036 polyvinylpyrrolidone Polymers 0.000 claims description 10
- 239000001267 polyvinylpyrrolidone Substances 0.000 claims description 10
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 claims description 10
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 claims description 10
- LPSKDVINWQNWFE-UHFFFAOYSA-M tetrapropylazanium;hydroxide Chemical compound [OH-].CCC[N+](CCC)(CCC)CCC LPSKDVINWQNWFE-UHFFFAOYSA-M 0.000 claims description 10
- 239000004952 Polyamide Substances 0.000 claims description 9
- 239000002253 acid Substances 0.000 claims description 9
- 239000003513 alkali Substances 0.000 claims description 9
- 238000001914 filtration Methods 0.000 claims description 9
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- 229910004298 SiO 2 Inorganic materials 0.000 claims description 8
- 239000002671 adjuvant Substances 0.000 claims description 7
- 239000003795 chemical substances by application Substances 0.000 claims description 7
- 150000007529 inorganic bases Chemical class 0.000 claims description 7
- 230000004913 activation Effects 0.000 claims description 5
- 150000001412 amines Chemical class 0.000 claims description 5
- 230000004927 fusion Effects 0.000 claims description 5
- 238000005216 hydrothermal crystallization Methods 0.000 claims description 5
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 4
- 239000010883 coal ash Substances 0.000 claims description 4
- 238000010438 heat treatment Methods 0.000 claims description 4
- WGTYBPLFGIVFAS-UHFFFAOYSA-M tetramethylammonium hydroxide Chemical group [OH-].C[N+](C)(C)C WGTYBPLFGIVFAS-UHFFFAOYSA-M 0.000 claims description 4
- 239000000377 silicon dioxide Substances 0.000 claims description 3
- 150000003384 small molecules Chemical class 0.000 claims description 3
- ZFPGARUNNKGOBB-UHFFFAOYSA-N 1-Ethyl-2-pyrrolidinone Chemical compound CCN1CCCC1=O ZFPGARUNNKGOBB-UHFFFAOYSA-N 0.000 claims description 2
- 239000004475 Arginine Substances 0.000 claims description 2
- KCXVZYZYPLLWCC-UHFFFAOYSA-N EDTA Chemical compound OC(=O)CN(CC(O)=O)CCN(CC(O)=O)CC(O)=O KCXVZYZYPLLWCC-UHFFFAOYSA-N 0.000 claims description 2
- ODKSFYDXXFIFQN-BYPYZUCNSA-P L-argininium(2+) Chemical compound NC(=[NH2+])NCCC[C@H]([NH3+])C(O)=O ODKSFYDXXFIFQN-BYPYZUCNSA-P 0.000 claims description 2
- HNDVDQJCIGZPNO-YFKPBYRVSA-N L-histidine Chemical compound OC(=O)[C@@H](N)CC1=CN=CN1 HNDVDQJCIGZPNO-YFKPBYRVSA-N 0.000 claims description 2
- KDXKERNSBIXSRK-YFKPBYRVSA-N L-lysine Chemical compound NCCCC[C@H](N)C(O)=O KDXKERNSBIXSRK-YFKPBYRVSA-N 0.000 claims description 2
- WHNWPMSKXPGLAX-UHFFFAOYSA-N N-Vinyl-2-pyrrolidone Chemical compound C=CN1CCCC1=O WHNWPMSKXPGLAX-UHFFFAOYSA-N 0.000 claims description 2
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 2
- ODKSFYDXXFIFQN-UHFFFAOYSA-N arginine Natural products OC(=O)C(N)CCCNC(N)=N ODKSFYDXXFIFQN-UHFFFAOYSA-N 0.000 claims description 2
- 239000002956 ash Substances 0.000 claims description 2
- 229960001484 edetic acid Drugs 0.000 claims description 2
- HNDVDQJCIGZPNO-UHFFFAOYSA-N histidine Natural products OC(=O)C(N)CC1=CN=CN1 HNDVDQJCIGZPNO-UHFFFAOYSA-N 0.000 claims description 2
- 239000007788 liquid Substances 0.000 claims description 2
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 2
- 229910000029 sodium carbonate Inorganic materials 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
- UIIMBOGNXHQVGW-DEQYMQKBSA-M Sodium bicarbonate-14C Chemical compound [Na+].O[14C]([O-])=O UIIMBOGNXHQVGW-DEQYMQKBSA-M 0.000 claims 1
- 239000002808 molecular sieve Substances 0.000 abstract description 16
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 abstract description 16
- 229910052710 silicon Inorganic materials 0.000 abstract description 11
- 239000010703 silicon Substances 0.000 abstract description 11
- 239000011148 porous material Substances 0.000 abstract description 9
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 abstract description 8
- 229910052782 aluminium Inorganic materials 0.000 abstract description 8
- 239000002910 solid waste Substances 0.000 abstract description 7
- 238000006555 catalytic reaction Methods 0.000 abstract description 5
- 238000001179 sorption measurement Methods 0.000 abstract description 5
- 230000015572 biosynthetic process Effects 0.000 abstract description 4
- 238000003786 synthesis reaction Methods 0.000 abstract description 4
- 238000012546 transfer Methods 0.000 abstract description 4
- 238000000926 separation method Methods 0.000 abstract description 2
- 239000000463 material Substances 0.000 description 22
- 239000008367 deionised water Substances 0.000 description 14
- 229910021641 deionized water Inorganic materials 0.000 description 14
- 230000000052 comparative effect Effects 0.000 description 12
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 10
- 239000013078 crystal Substances 0.000 description 9
- 238000002441 X-ray diffraction Methods 0.000 description 8
- -1 polytetrafluoroethylene Polymers 0.000 description 8
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 8
- 239000004810 polytetrafluoroethylene Substances 0.000 description 8
- 239000002994 raw material Substances 0.000 description 8
- 238000007670 refining Methods 0.000 description 8
- 229910001220 stainless steel Inorganic materials 0.000 description 8
- 239000010935 stainless steel Substances 0.000 description 8
- 239000004570 mortar (masonry) Substances 0.000 description 7
- 239000000843 powder Substances 0.000 description 7
- 238000012216 screening Methods 0.000 description 7
- 239000002105 nanoparticle Substances 0.000 description 6
- 239000002245 particle Substances 0.000 description 6
- 238000001027 hydrothermal synthesis Methods 0.000 description 4
- 239000000376 reactant Substances 0.000 description 4
- 238000002336 sorption--desorption measurement Methods 0.000 description 4
- CSDREXVUYHZDNP-UHFFFAOYSA-N alumanylidynesilicon Chemical compound [Al].[Si] CSDREXVUYHZDNP-UHFFFAOYSA-N 0.000 description 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 3
- 239000003054 catalyst Substances 0.000 description 3
- 230000003197 catalytic effect Effects 0.000 description 3
- 230000002194 synthesizing effect Effects 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
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- 230000004048 modification Effects 0.000 description 2
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- 235000012239 silicon dioxide Nutrition 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- 238000004438 BET method Methods 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 241000669618 Nothes Species 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 230000003213 activating effect Effects 0.000 description 1
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- 230000029936 alkylation Effects 0.000 description 1
- 238000005804 alkylation reaction Methods 0.000 description 1
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical class [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 1
- 229910000323 aluminium silicate Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
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- 230000001788 irregular Effects 0.000 description 1
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- 238000002386 leaching Methods 0.000 description 1
- 125000003588 lysine group Chemical group [H]N([H])C([H])([H])C([H])([H])C([H])([H])C([H])([H])C([H])(N([H])[H])C(*)=O 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
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- 230000003472 neutralizing effect Effects 0.000 description 1
- 150000007530 organic bases Chemical class 0.000 description 1
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
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- 229910000030 sodium bicarbonate Inorganic materials 0.000 description 1
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- 230000001360 synchronised effect Effects 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
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Images
Abstract
The invention discloses a preparation method of mesoporous-rich fly ash-based MFI structure nano zeolite, and belongs to the technical field of resource utilization of industrial solid wastes and zeolite synthesis. The zeolite prepared by the method has an MFI framework topological structure, the grain size of 100-500 nm and the mesopore ratio of 64-85%. The invention not only synthesizes the mesoporous-rich nano zeolite molecular sieve, but also realizes the utilization of silicon and aluminum resources in the fly ash, and provides a high-yield and simple preparation method of the fly ash-based MFI structure nano zeolite. Compared with the traditional molecular sieve, the mesopores can effectively reduce the mass transfer limitation of the micropores, and the specific surface area of the porous material can be improved by the nanoscale, so that the application of the porous material in the fields of catalysis, adsorption, separation and the like is expanded.
Description
Technical Field
The invention belongs to the technical field of resource utilization of industrial solid wastes and zeolite synthesis, and particularly relates to a preparation method of fly ash-based MFI structure nano zeolite rich in mesopores.
Background
As the economic high-speed development of China in recent decades and the power consumption are continuously improved, the increase of the solid waste coal ash of a coal-fired power plant is directly caused, the coal ash not only occupies a large amount of land resources and increases the management cost, but also can seriously damage the ecological environment, and therefore a reasonable treatment method is urgently needed. Zeolite is a crystal composed of aluminosilicate and having a specific pore structure, and is widely used in the fields of catalysis, adsorption, ion exchange and the like. Because the fly ash contains a large amount of SiO 2 And Al 2 O 3 The silicon source and the aluminum source in chemical agents can be replaced, so that the production cost of the molecular sieve is greatly reduced, and the value-added utilization of solid wastes is realized. Therefore, the preparation of zeolite by using fly ash as a raw material is one of effective ways for high-value utilization of solid wastes.
Common zeolites synthesized by using fly ash as a raw material comprise topological structures such as LTA, FAU, FER, MFI and the like, and the adopted method is mainly a hydrothermal synthesis method. The zeolite is usually prepared by grinding, high-temperature roasting, acid leaching, alkali dissolving, neutralizing and the like of fly ash, respectively extracting, separating and purifying active components such as silicon, aluminum and the like in the fly ash, then taking obtained silicon dioxide and aluminum oxide as a silicon source and an aluminum source, then adding an organic template agent, inorganic alkali and water, and then utilizing a hydrothermal synthesis method. The zeolite products with different structure types are obtained by adjusting the raw material proportion of the initial sol, the types of the organic template agents and the conditions of the hydrothermal crystallization process. The MFI-type structure zeolite synthesized by the traditional process is a microporous material, has large particle size, generates a large amount of acid and alkali wastewater and forms secondary pollution.
The MFI structure zeolite is formed from TO 4 Tetrahedron being built up of basic building blocks, TO 4 The five-membered rings are formed by sharing oxygen bridges between the eight five-membered rings, then structural units formed by the eight five-membered rings are connected through a common edge to form a Pentasil chain, and the chain are connected to form a three-dimensional framework, so that the Pentasil structure is often used as a solid acid catalyst, an adsorbent and a membrane separation material for alkylation, disproportionation, isomerization, catalytic cracking and the like. At present, the raw materials adopted for artificially synthesizing the MFI zeolite are generally silicon salt, aluminum salt and noThe organic base and organic template agent are synthesized by hydrothermal synthesis, solid phase synthesis, xerogel synthesis, etc.
Currently, MFI structure zeolite synthesized from fly ash is generally microporous zeolite with a particle size of micron order. Although the microporous zeolite has obvious advantages in adsorption, ion exchange and partial catalytic reaction, due to the limitation of a single pore channel, the contact of reactants and adsorbates with larger molecular sizes and the like with active sites on the inner surface of the material is prevented, and the limitation of the micropores on mass transfer can be effectively reduced by virtue of mesopores. Meanwhile, compared with the micron-sized molecular sieve, the nanoscale molecular sieve has larger external surface area, more external surface active centers and shorter and regular pore channels, which means that reactants can contact more active sites, and the nanoscale molecular sieve has better carbon deposit resistance and stability in catalytic application.
In recent years, attempts have been made to prepare MFI structure zeolite having a specific structure and morphology from fly ash. CN112194150A uses fly ash as a raw material, utilizes a microwave-ultrasonic-ultraviolet light synergistic activation technology to substitute a traditional high-energy-consumption alkali fusion technology to synthesize MFI structure zeolite with multi-level pore channels, but the synthesized zeolite has larger particle size and less mesopore occupation, and the method is difficult to realize industrial production; CN103435064B discloses a method for preparing a nano-sized ZSM-5 molecular sieve by using fly ash, although the nano-sized ZSM-5 molecular sieve prepared by microwave-assisted hydrothermal synthesis has good crystallinity, but lacks mesopores, so that the application field is limited, and industrial production and application are difficult to realize; CN111646486B discloses a method for directly synthesizing a needed ZSM-5 molecular sieve by adding a template and a silicon source material to form dry glue without pretreatment and any pretreatment operation for extracting aluminum and silicon, and further performing steam crystallization treatment and high-temperature calcination.
At present, no report is found on the synthesis of MFI zeolite with nano-particle size and rich mesoporous channels by using fly ash as a raw material.
Disclosure of Invention
In view of this, the invention provides a preparation method of fly ash-based MFI structure zeolite with nano-particle size and rich mesoporous channels.
The invention uses fly ash solid waste rich in silicon and aluminum as raw material to realize the synchronous utilization of silicon and aluminum resources in fly ash, and finds a preparation method for synthesizing fly ash-based MFI nano zeolite by adding coadjuvant PL, the synthesized zeolite has smaller particle size on one hand, which results in larger specific surface area compared with common zeolite, so that more active centers are exposed; on the other hand, the zeolite is rich in mesoporous channels, and compared with the traditional molecular sieve, mesopores can effectively reduce the mass transfer limitation of micropores, so that reactants can be more easily contacted with the active center on the inner surface of the catalyst, and the catalytic activity of the material is improved. The invention has obvious economic value by converting the fly ash from solid waste into inorganic material with high added value.
In order to achieve the purpose, the invention adopts the technical scheme that:
a preparation method of fly ash-based MFI structure nano zeolite rich in mesopores comprises the following steps:
(1) Grinding: grinding the fly ash to reach the standard of third-grade ash;
(2) Acid washing: mixing the fly ash obtained in the step (1) with water, fully dissolving and stirring at the stirring speed of 500rpm, adding a certain amount of concentrated hydrochloric acid, and continuously stirring for 2-4 hours for later use;
(3) And (3) calcining: calcining the fly ash obtained in the step (2) in a muffle furnace at high temperature, wherein the calcining temperature is 600-850 ℃, the heating rate is 3-5 ℃/min, and the calcining time is 4-6 h;
(4) Alkali fusion activation: mixing the fly ash obtained in the step (3) with inorganic base, uniformly mixing according to the molar ratio of the silicon dioxide in the fly ash to the inorganic base of 0.13-0.26 by calculation, fully grinding, roasting in a muffle furnace at 550-800 ℃ for 2-6 h at the heating rate of 3-5 ℃/min, cooling, and grinding to obtain activated fly ash;
(5) Initial sol preparation: mixing the activated fly ash obtained in the step (4) with an organic template agent (SDA), inorganic base, a coadjuvant PL and water according to a certain proportion, fully dissolving and stirring, keeping the stirring speed unchanged, and adding a certain amount of silica sol to obtain initial sol;
(6) Hydrothermal crystallization: stirring and aging the initial sol obtained in the step (5) at room temperature for 2-6 h, wherein the aging stirring speed is 1000-2000 rpm, placing the aged initial sol into a stainless steel reaction kettle with a polytetrafluoroethylene lining, performing dynamic rotary crystallization on the reaction kettle at the rotation speed of 8-16 rpm, the crystallization temperature of 140-200 ℃, and the crystallization time of 48-120 h;
(7) And (3) calcining: and after crystallization is finished, cooling the product to room temperature, filtering, washing and drying, and finally roasting at the temperature of 450-580 ℃ for 4-8 h at the heating rate of 3-5 ℃/min to obtain the fly ash-based MFI structure zeolite.
Specifically, fly ash is pretreated by grinding, acid washing, calcining and alkali fusion activation, and serves as the sole source of aluminum and a partial source of silicon in the zeolite product. The silica sol is added to adjust the silica-alumina ratio of the initial sol, organic amine is added to serve as a structure directing agent, a coadjuvant PL consisting of water-soluble polyamide and water-soluble organic micromolecules is added at the same time, the silica-alumina ratio in the initial sol and the composition and the using amount of the coadjuvant PL are regulated, and the MFI structure zeolite is synthesized through constant-temperature hydrothermal crystallization under autogenous pressure.
The method not only synthesizes the zeolite molecular sieve with nano particle size and rich mesoporous pore channels, but also realizes the simultaneous utilization of silicon-aluminum resources in the fly ash, provides the simple fly ash-based MFI structure zeolite with high yield and low emission, realizes the reutilization of waste resources, reduces the production cost of the MFI structure zeolite, has higher economic value, and simultaneously synthesizes the zeolite with larger specific surface area and mesoporous pore volume, thereby being beneficial to catalytic reaction and adsorption performance.
Preferably, in the acid washing in the step (2), the concentration of the hydrochloric acid is 5% -10%, and the solid-to-liquid ratio (g/ml) of the fly ash to the acid washing solution is 1: (10 to 40).
Preferably, the inorganic base used in the alkali fusion activation in step (4) may be one of sodium hydroxide, sodium carbonate and sodium bicarbonate.
Preferably, in the step (5), the organic template is a combination of one or more organic amine templates, and the organic amine template is tetramethylammonium hydroxide, tetraethylammonium hydroxide or tetrapropylammonium hydroxide;
the coadjuvant PL is composed of water-soluble polyamide and water-soluble organic micromolecules, and the water-soluble polyamide is one or a mixture of polyvinylpyrrolidone, N-vinyl pyrrolidone, N-ethyl pyrrolidone; the water-soluble organic micromolecules are one of arginine, histidine, lysine, ethylene diamine tetraacetic acid and polyvinyl alcohol.
Further, the mass ratio of the water-soluble polyamide to the water-soluble organic small molecule is (0.2-3.6): 1; the mass ratio of the coadjuvant PL to the added water is (0.03-0.12): 1.
further, the organic template agent is tetrapropylammonium hydroxide, the water-soluble polyamide is polyvinylpyrrolidone, and the water-soluble organic small molecule is lysine.
Preferably, the molar ratio of each component in the initial sol is SiO 2 :Al 2 O 3 :NaOH:SDA:PL:H 2 O＝1:0.033～0.02:0.15～0.5:0.2～0.5:0.02～0.25:10～30。
According to the technical scheme, compared with the prior art, the preparation method of the mesoporous-rich fly ash-based MFI structure nano zeolite provided by the invention has the following excellent effects:
1. the MFI structure zeolite is prepared by taking waste fly ash of a coal-fired power plant as a raw material, grinding and refining, acid-washing, alkali-melting and activating silicon-aluminum elements in the fly ash, and then performing dynamic hydrothermal crystallization, so that the high value of the fly ash is realized, and the MFI structure zeolite which can be widely applied to catalysis and adsorption is synthesized.
2. According to the invention, the coadjuvant consisting of water-soluble polyamide and water-soluble organic micromolecules is added into the concentrated sol, so that the size of the molecular sieve crystal grains is reduced, and simultaneously, the function of introducing mesoporous channels into the crystals is achieved; the MFI structure molecular sieve with nano-grain diameter and rich mesoporous channels can be prepared by the method disclosed by the invention.
3. The invention provides a preparation method of fly ash-based MFI structure zeolite with nano particle size and rich mesoporous channels by adding co-adjuvant PL, on one hand, the synthesized zeolite has smaller particle size, so that more active centers are exposed; on the other hand, the zeolite is rich in mesoporous channels, and compared with the traditional molecular sieve, mesopores can effectively reduce the mass transfer limitation of micropores, so that reactants can be more easily contacted with the active center on the inner surface of the catalyst, and the catalytic activity of the material is improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the provided drawings without creative efforts.
Fig. 1 is an XRD pattern of the MFI-type zeolite of example 1.
Fig. 2 is an SEM picture of MFI-type zeolite in example 1.
FIG. 3 is a BET diagram of the MFI-type zeolite of example 1.
Fig. 4 is an XRD pattern of the MFI-type zeolite in comparative example 2.
Figure 5 is an XRD pattern of the MFI-type zeolite of example 3.
Figure 6 is an XRD pattern of the MFI-type zeolite of example 4.
Figure 7 is an XRD pattern of the MFI-type zeolite of example 5.
Figure 8 is an XRD pattern of the MFI-type zeolite of example 6.
Fig. 9 is an XRD pattern of the MFI-type zeolite in comparative example 1.
Fig. 10 is an SEM image of the MFI-type zeolite in comparative example 1.
Fig. 11 is a BET diagram of the MFI-type zeolite in comparative example 1.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention and the accompanying drawings of the specification, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The embodiment of the invention discloses a preparation method of fly ash-based MFI structure nano zeolite rich in mesopores.
The present invention will be further specifically illustrated by the following examples for better understanding, but the present invention is not to be construed as being limited thereto, and certain insubstantial modifications and adaptations of the invention by those skilled in the art based on the foregoing disclosure are intended to be included within the scope of the invention.
The technical solution of the present invention will be further described with reference to the following specific examples.
And simultaneously, performing appearance and structure characterization tests on the prepared MFI type zeolite, which specifically comprises the following steps:
fig. 1, fig. 4, fig. 5, fig. 6, fig. 7, fig. 8, fig. 9 were scanned at a scanning angle of 2 θ =5 ° -50 ° by using a german BRUKER D8 Focus type X-ray diffractometer (XRD), cu — K α as a radiation source, a tube voltage of 40KV, a tube current of 40mA, a scanning rate of 2 °/min.
FIGS. 2 and 10 show the results obtained by using a Scanning Electron Microscope (SEM) of JSM-6490LV type, a Japanese Electron company, with an acceleration voltage of 10 to 20kV, in which a molecular sieve sample was sufficiently dispersed in an ethanol solution by ultrasonic waves before the test.
FIG. 3 and FIG. 11 show that the specific surface area and pore size analyzer (BET) of Chinese 3H-2000PM1 Behcet is degassed at 200 deg.C for 4H before testing, the specific surface is calculated by BET method, and the mesopore ratio is calculated by BJH method.
Example 1
The embodiment 1 of the invention discloses a preparation method of fly ash-based MFI structure nano zeolite rich in mesopores, which comprises the following steps:
(1) Grinding and refining the fly ash by using a powder machine, and screening out finer fly ash by using a 200-mesh screen;
(2) Adding 10.0g of fly ash material into a 500mL three-neck flask, then adding 190.0mL of deionized water and 10.0mL of concentrated hydrochloric acid, fully dissolving and stirring at the stirring speed of 500rpm, and continuously stirring for 2 hours; then, washing and drying the fly ash;
(3) Calcining the obtained fly ash in a muffle furnace at a high temperature of 800 ℃ for 4h;
(4) 1.0g of calcined fly ash is taken, uniformly mixed with 1.2g of NaOH, fully ground by using an agate mortar, then roasted for 4 hours in a muffle furnace at 550 ℃, cooled and ground to obtain an activated fly ash material;
(5) In a 250mL three-necked flask, a mass of 2.2g of activated fly ash was added, followed by 18.6mL of deionized water and 27.2mL of tetrapropylammonium hydroxide, as well as 1.5g of polyvinylpyrrolidone and 2.5g of lysine, vigorous stirring was initiated at 1200rpm, the stirring rate was maintained, and 22.2mL of silica sol was added during stirring to give a mixture having a SiO molar ratio 2 :Al 2 O 3 :NaOH:SDA:PL:H 2 O =1, 0.4;
(6) Stirring and aging the initial sol at room temperature for 4h, wherein the rotation speed of the aging and stirring is 1500rpm, then transferring the initial sol to a stainless steel reaction kettle with a polytetrafluoroethylene lining, dynamically rotating and crystallizing the reaction kettle at the rotation speed of 12rpm, and crystallizing the initial sol for 72h at the temperature of 175 ℃.
(7) And after crystallization is finished, cooling the product to room temperature, filtering, washing and drying, and finally roasting at 550 ℃ for 6 hours to obtain the MFI structure zeolite.
The product was characterized using an X-ray diffractometer (XRD) and a Scanning Electron Microscope (SEM). From the XRD pattern, characteristic diffraction peaks of MFI topology at 2 θ =7.9 °,8.9 °,23.1 °,23.9 ° and 24.4 ° were seen, and have higher peak intensities.
By adding a certain amount of the coadjuvant PL, it was confirmed that the obtained sample remained MF, as compared with comparative example 1 (MFI zeolite prepared without adding the coadjuvant PL)The relative crystallinity of the I zeolite is 63.82 percent, the yield is 72.53 percent, and SEM pictures show that the sample is uniformly dispersed and is in a cuboid shape or an ellipsoid shape, and the crystal size is about 100-300 nm. N is a radical of 2 The adsorption-desorption experiment shows that the specific surface area of the sample is 354.24m 2 The proportion of mesopores reaches 75.61 percent per gram, from N 2 The adsorption-desorption curve shows that the product synthesized by adding the coadjuvant has obvious hysteresis loop, which indicates that the product has rich mesoporous structure.
Example 2
The embodiment 2 of the invention discloses a preparation method of fly ash-based MFI structure zeolite, which reduces the silicon-aluminum ratio of ingredients, and specifically comprises the following steps:
(1) Grinding and refining the fly ash by using a powder machine, and screening out finer fly ash by using a 200-mesh screen;
(2) In a 500mL three-neck flask, 10.0g of fly ash material is added, then 190.0mL of deionized water and 10mL of concentrated hydrochloric acid are added to be fully dissolved and stirred, the stirring speed is 500rpm, and the stirring is continued for 2 hours. And then washing and drying the fly ash.
(3) Calcining the obtained fly ash in a muffle furnace at a high temperature of 800 ℃ for 4h;
(4) Taking 1.0g of calcined fly ash, uniformly mixing the calcined fly ash with 1.2g of NaOH, fully grinding the mixture by using an agate mortar, then roasting the mixture for 4 hours in a muffle furnace at 550 ℃, and then cooling and grinding the roasted fly ash to obtain an activated fly ash material;
(5) In a 250mL three-necked flask, a mass of 2.2g of activated fly ash was added, followed by 26.2mL of deionized water and 22.4mL of tetrapropylammonium hydroxide, as well as 1.5g of polyvinylpyrrolidone and 2.5g of lysine, vigorous stirring was initiated at 1200rpm, the stirring rate was maintained, and 16.3mL of silica sol was added during stirring to obtain a mixture having a SiO molar ratio 2 :Al 2 O 3 :NaOH:SDA:PL:H 2 O =1, 0.033;
(6) Stirring and aging the initial sol at room temperature for 4h, wherein the aging and stirring speed is 1200rpm, then transferring the initial sol to a stainless steel reaction kettle with a polytetrafluoroethylene lining, dynamically rotating the reaction kettle for crystallization, wherein the rotation speed is 12rpm, and crystallizing for 72h at the temperature of 175 ℃.
(7) And after crystallization is finished, cooling the product to room temperature, filtering, washing and drying, and finally roasting at 550 ℃ for 6 hours to obtain the MFI structure zeolite.
The product was characterized by XRD and SEM.
In comparison with comparative example 1 (MFI zeolite prepared without the addition of co-adjuvant PL), the product remained MFI zeolite with the addition of co-adjuvant PL and a simultaneous reduction of the silica-alumina ratio to 30, the relative crystallinity was 50.73%, the yield was 79.67%, the sample was ellipsoidal, the crystal size was about 200 to 400nm, and the specific surface area was 326.51m 2 The proportion of mesopores is 71.35 percent.
Example 3
The invention embodiment 3 discloses a preparation method of fly ash-based MFI structure zeolite, which reduces the dosage of a coadjuvant PL in initial gel, and specifically comprises the following steps:
(1) Grinding and refining the fly ash by using a powder machine, and screening out finer fly ash by using a 200-mesh screen;
(2) In a 500mL three-neck flask, 10.0g of fly ash material is added, then 190.0mL of deionized water and 10.0mL of concentrated hydrochloric acid are added to be fully dissolved and stirred, the stirring speed is 500rpm, and the stirring is continued for 2h. And then washing and drying the fly ash.
(3) Calcining the obtained fly ash in a muffle furnace at a high temperature of 800 ℃ for 4h;
(4) 1.0g of calcined fly ash is taken, uniformly mixed with 1.2g of NaOH, fully ground by using an agate mortar, then roasted for 4 hours in a muffle furnace at 550 ℃, cooled and ground to obtain an activated fly ash material;
(5) In a 250mL three-necked flask, 2.2g of activated fly ash material was added, followed by 18.6mL of deionized water and 28.0mL of tetrapropylammonium hydroxide, as well as 1.0g of polyvinylpyrrolidone and 1.6g of lysine, vigorous stirring was started, specifically at 1200rpm, and the stirring rate was maintained, and 27.2mL of silica sol was added during stirring, so thatThe molar ratio of the mixture is SiO 2 :Al 2 O 3 :NaOH:SDA:PL:H 2 O =1, 0.4;
(6) Stirring and aging the initial sol at room temperature for 4h, wherein the rotation speed of aging and stirring is 1200rpm, then transferring the initial sol to a stainless steel reaction kettle with a polytetrafluoroethylene lining, dynamically rotating and crystallizing the reaction kettle at the rotation speed of 12rpm, and crystallizing the initial sol for 72h at the temperature of 175 ℃.
(7) And after crystallization is finished, cooling the product to room temperature, filtering, washing and drying, and finally roasting at 550 ℃ for 6 hours to obtain the MFI structure zeolite.
The product was characterized by XRD and SEM.
In comparison with comparative example 1 (MFI zeolite prepared without addition of coadjuvant PL), it was found that when the coadjuvant PL to silicon ratio in the initial gel was increased to 0.1, the product remained as an MFI zeolite, the relative crystallinity was 64.11%, the yield was 65.16%, the sample was in an ellipsoidal shape, the crystal size was about 300 to 700nm, and the specific surface area was 301.97m 2 The proportion of mesopores is 62.31 percent per gram.
Example 4
Increasing the dosage of the coadjuvant PL in the initial gel, embodiment 4 of the invention discloses a preparation method of fly ash-based MFI structure zeolite, which specifically comprises the following steps:
(1) Grinding and refining the fly ash by using a powder machine, and screening out finer fly ash by using a 200-mesh screen;
(2) In a 500mL three-neck flask, 10.0g of fly ash material is added, then 190.0mL of deionized water and 10.0mL of concentrated hydrochloric acid are added to be fully dissolved and stirred, the stirring speed is 500rpm, and stirring is continued for 2h. And then washing and drying the fly ash.
(3) Calcining the obtained fly ash in a muffle furnace at a high temperature of 800 ℃ for 4h;
(4) Taking 1.0g of calcined fly ash, uniformly mixing the calcined fly ash with 1.2g of NaOH, fully grinding the mixture by using an agate mortar, then roasting the mixture for 4 hours in a muffle furnace at 550 ℃, and then cooling and grinding the roasted fly ash to obtain an activated fly ash material;
(5) In a 250mL three-necked flask, a mass of 2.2g of activated fly ash was added, followed by 18.6mL of deionized water and 22.4mL of tetrapropylammonium hydroxide, as well as 2.0g of polyvinylpyrrolidone and 3.1g of lysine, vigorous stirring was started at 1200rpm, the stirring rate was maintained, and 27.2mL of silica sol was added during stirring so that the molar ratio of the mixture was SiO 2 :Al 2 O 3 :NaOH:SDA:PL:H 2 O =1, 0.4;
(6) Stirring and aging the initial sol at room temperature for 4h, wherein the rotation speed of aging and stirring is 1200rpm, then transferring the initial sol to a stainless steel reaction kettle with a polytetrafluoroethylene lining, dynamically rotating and crystallizing the reaction kettle at the rotation speed of 12rpm, and crystallizing the initial sol for 72h at the temperature of 175 ℃.
(7) And after crystallization is finished, cooling the product to room temperature, filtering, washing and drying, and finally roasting at 550 ℃ for 6 hours to obtain the MFI structure zeolite.
The product was characterized by XRD.
In comparison with comparative example 1 (MFI zeolite prepared without addition of co-adjuvant PL), it was found that when the co-adjuvant PL to silicon ratio in the initial gel was increased to 0.2, the product remained as an MFI zeolite, the relative crystallinity was reduced to 39.27%, the yield was 76.59%, the crystal size was about 300 to 500nm, and the specific surface area of the sample was 276.85m 2 The proportion of mesopores is up to 65.43 percent per gram.
Example 5
The embodiment 5 of the invention discloses a preparation method of fly ash-based MFI structure zeolite, which only adds polyvinylpyrrolidone in a coadjuvant PL, and specifically comprises the following steps:
(1) Grinding and refining the fly ash by using a powder machine, and screening out finer fly ash by using a 200-mesh screen;
(2) In a 500mL three-neck flask, 10.0g of fly ash material is added, then 190.0mL of deionized water and 10.0mL of concentrated hydrochloric acid are added to be fully dissolved and stirred, the stirring speed is 500rpm, and the stirring is continued for 2h. And then washing and drying the fly ash.
(3) Calcining the obtained fly ash in a muffle furnace at a high temperature of 800 ℃ for 4h;
(4) Taking 1.0g of calcined fly ash, uniformly mixing the calcined fly ash with 1.2g of NaOH, fully grinding the mixture by using an agate mortar, then roasting the mixture for 4 hours in a muffle furnace at 550 ℃, and then cooling and grinding the roasted fly ash to obtain an activated fly ash material;
(5) In a 250mL three-necked flask, 2.2g of the activated fly ash material was added, followed by 18.6mL of deionized water and 22.4mL of tetrapropylammonium hydroxide, and 1.5g of polyvinylpyrrolidone was added, vigorous stirring was started at 1200rpm, the stirring rate was maintained, and 27.2mL of silica sol was added during stirring so that the molar ratio of the mixture was SiO 2 :Al 2 O 3 :NaOH:SDA:PL:H 2 O =1, 0.025;
(6) Stirring and aging the initial sol at room temperature for 4h, wherein the rotation speed of aging and stirring is 1200rpm, then transferring the initial sol to a stainless steel reaction kettle with a polytetrafluoroethylene lining, dynamically rotating and crystallizing the reaction kettle at the rotation speed of 12rpm, and crystallizing the initial sol for 72h at the temperature of 175 ℃.
(7) And after crystallization is finished, cooling the product to room temperature, filtering, washing and drying, and finally roasting at 550 ℃ for 6 hours to obtain the MFI structure zeolite.
The product was characterized by XRD.
In comparison with comparative example 1 (MFI zeolite prepared without addition of coadjuvant PL), the product remained MFI zeolite with the addition of polyvinylpyrrolidone alone, the relative crystallinity of 69.20%, the yield of 67.32%, the crystal size of about 500 to 800nm, and the specific surface area of the sample of 267.58m 2 The proportion of mesopores is 52.33 percent per gram.
Example 6
The embodiment 6 of the invention discloses a preparation method of fly ash-based MFI structure zeolite by only adding lysine in a coadjuvant PL, which specifically comprises the following steps:
(1) Grinding and refining the fly ash by using a powder machine, and screening out finer fly ash by using a 200-mesh screen;
(2) In a 500mL three-neck flask, 10.0g of fly ash material is added, then 190.0mL of deionized water and 10.0mL of concentrated hydrochloric acid are added to be fully dissolved and stirred, the stirring speed is 500rpm, and stirring is continued for 2h. And then washing and drying the fly ash.
(3) Calcining the obtained fly ash in a muffle furnace at a high temperature of 800 ℃ for 4h;
(4) 1.0g of calcined fly ash is taken, uniformly mixed with 1.2g of NaOH, fully ground by using an agate mortar, then roasted for 4 hours in a muffle furnace at 550 ℃, cooled and ground to obtain an activated fly ash material;
(5) In a 250mL three-necked flask, a mass of 2.2g of activated fly ash was added, followed by 18.6mL of deionized water and 22.4mL of tetrapropylammonium hydroxide, and 2.5g of lysine, vigorous stirring was initiated at 1200rpm, the stirring rate was maintained, and 27.2mL of silica sol was added during stirring to give a mixture having a molar ratio of SiO 2 :Al 2 O 3 :NaOH:SDA:PL:H 2 O =1, 0.4;
(6) Stirring and aging the initial sol at room temperature for 4h, wherein the rotation speed of aging and stirring is 1200rpm, then transferring the initial sol to a stainless steel reaction kettle with a polytetrafluoroethylene lining, dynamically rotating and crystallizing the reaction kettle at the rotation speed of 12rpm, and crystallizing the initial sol for 72h at the temperature of 175 ℃.
(7) And after crystallization is finished, cooling the product to room temperature, filtering, washing and drying, and finally roasting at 550 ℃ for 6 hours to obtain the MFI structure zeolite.
The product was characterized by XRD.
In comparison with comparative example 1 (MFI zeolite prepared without addition of co-adjuvant PL), the product remained MFI zeolite with the addition of lysine alone, the relative crystallinity of 74.18%, the yield of 74.23%, the crystal size of about 500 to 800nm, and the specific surface area of the sample of 274.68m 2 The proportion of mesopores is 53.45 percent per gram.
Comparative example 1
Comparative example 1 according to the present invention, MFI structure zeolite was directly prepared by a method without adding coadjuvant PL, and specifically included the following steps:
(1) Grinding and refining the fly ash by using a powder machine, and screening out finer fly ash by using a 200-mesh screen;
(2) In a 500mL three-neck flask, 10.0g of fly ash material is added, then 190.0mL of deionized water and 10.0mL of concentrated hydrochloric acid are added to be fully dissolved and stirred, the stirring speed is 500rpm, and the stirring is continued for 2h. And then washing and drying the fly ash.
(3) Calcining the obtained fly ash in a muffle furnace at a high temperature of 800 ℃ for 4h;
(4) Taking 1g of calcined fly ash, uniformly mixing the calcined fly ash with 1.2g of NaOH, fully grinding the mixture by using an agate mortar, then roasting the mixture for 4 hours in a muffle furnace at 550 ℃, and then cooling and grinding the mixture to obtain an activated fly ash material;
(5) In a 250mL three-necked flask, 2.2g of activated fly ash material was added, followed by 18.6mL of deionized water and 22.4mL of tetrapropylammonium hydroxide, vigorous stirring was started at 1800rpm, the stirring rate was maintained, and 27.2mL of silica sol was added during stirring so that the molar ratio of the mixture was SiO 2 :Al 2 O 3 :NaOH:SDA:H 2 O =1, 0.4;
(6) Stirring and aging the initial sol at room temperature for 4h, wherein the rotation speed of aging and stirring is 1800rpm, then transferring the initial sol to a stainless steel reaction kettle with a polytetrafluoroethylene lining, dynamically rotating and crystallizing the reaction kettle at the rotation speed of 12rpm, and crystallizing the initial sol for 72h at the temperature of 175 ℃.
(7) And after crystallization is finished, cooling the product to room temperature, filtering, washing and drying, and finally roasting at 550 ℃ for 6 hours to obtain the MFI structure zeolite.
The product was characterized by XRD and SEM and BET.
The yield of the MFI molecular sieve prepared without adding the coadjuvant PL is 80.49%, the sample is observed to be irregular in shape and different in size through SEM (scanning electron microscope) pictures, and the particle size of the sample is 200-1000 nm. N is a radical of 2 The adsorption-desorption experiment shows that the specific surface area of the sample is 319.22m 2 (ii)/g, the mesopore ratio is 36.85%, from N 2 The adsorption-desorption curve shows that the product without the coadjuvant has no obvious hysteresis loop, which indicates that the product has fewer mesopores.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (8)
1. A preparation method of fly ash-based MFI structure nano zeolite rich in mesopores is characterized by comprising the following steps:
(1) Grinding: grinding the fly ash to reach the standard of third-grade ash;
(2) Acid washing: mixing the fly ash obtained in the step (1) with water, fully dissolving and stirring, then adding concentrated hydrochloric acid, and continuously stirring for 2-4 hours for later use;
(3) And (3) calcining: calcining the fly ash obtained in the step (2) at high temperature;
(4) Alkali fusion activation: mixing the fly ash obtained in the step (3) with inorganic alkali, fully grinding and roasting to obtain activated fly ash;
(5) Initial sol preparation: mixing the activated fly ash obtained in the step (4) with an organic template agent SDA, inorganic base, a co-adjuvant PL and water, fully dissolving and stirring, and then adding silica sol to obtain initial sol on the premise of maintaining the stirring rate;
(6) Hydrothermal crystallization: stirring and aging the initial sol obtained in the step (5) at room temperature for 2-6 h, and then placing the initial sol in a reaction kettle for dynamic rotation crystallization;
(7) And (3) calcining: and (5) after the crystallization in the step (6) is finished, cooling the product to room temperature, filtering, washing and drying, and finally roasting at high temperature to obtain the fly ash-based MFI structure nano zeolite rich in mesopores.
2. The preparation method of the fly ash-based MFI structure nano zeolite rich in mesopores according to claim 1, wherein in the acid washing in the step (2), the concentration of the hydrochloric acid is 5-10%, and the solid-to-liquid ratio of the fly ash to the acid washing solution is 1: (10 to 40).
3. The method for preparing the coal ash-based MFI structure nano zeolite rich in mesopores according to claim 1, wherein the calcination temperature in step (3) is 600 ℃ to 850 ℃, the calcination time is 4 to 6 hours, the calcination temperature in step (4) is 550 ℃ to 800 ℃, the calcination time is 2 to 6 hours, the calcination temperature in step (7) is 450 ℃ to 580 ℃, and the calcination time is 4 to 8 hours; the heating rate in the calcining step is 3-5 ℃/min.
4. The method for preparing the MFI structure nano zeolite based on fly ash rich in mesopores as claimed in claim 1, wherein in step (4), the inorganic base is sodium hydroxide, sodium carbonate or sodium bicarbonate, and the molar ratio of silica to inorganic base in fly ash is (0.13-0.26): 1, uniformly mixing.
5. The method for preparing the MFI structure nano zeolite based on fly ash rich in mesopores as claimed in claim 1, wherein in step (5), the organic template is a combination of one or more organic amine templates, and the organic amine template is tetramethylammonium hydroxide, tetraethylammonium hydroxide or tetrapropylammonium hydroxide;
the coadjuvant PL is composed of water-soluble polyamide and water-soluble organic micromolecules, and the water-soluble polyamide is one or a mixture of polyvinylpyrrolidone, N-vinyl pyrrolidone, N-ethyl pyrrolidone; the water-soluble organic micromolecules are one of arginine, histidine, lysine, ethylene diamine tetraacetic acid and polyvinyl alcohol.
6. Root of herbaceous plantsThe method for preparing a fly ash-based MFI structure nano zeolite rich in mesopores according to claim 1 or 5, wherein in step (5), the molar ratio of each component in the initial sol is SiO 2 :Al 2 O 3 :NaOH:SDA:PL:H 2 O＝1:0.033～0.02:0.15～0.5:0.2～0.5:0.02～0.25:10～30。
7. The preparation method of the fly ash-based MFI structure nano zeolite rich in mesopores according to claim 5, wherein the mass ratio of the water-soluble polyamide to the water-soluble organic small molecule is (0.2-3.6): 1; the mass ratio of the coadjuvant PL to the added water is (0.03-0.12): 1.
8. the method for preparing the coal ash-based MFI structure nano zeolite rich in mesopores according to claim 1, wherein the aging stirring rotation speed in the step (6) is 1000 to 2000r/min, and the dynamic rotation crystallization rotation speed is 8 to 16r/min; the crystallization temperature is 140-200 ℃, and the crystallization time is 48-120 h.
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