CN111892065A - Method for preparing SAPO-34 molecular sieve by using rice hulls as silicon source - Google Patents
Method for preparing SAPO-34 molecular sieve by using rice hulls as silicon source Download PDFInfo
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- 235000007164 Oryza sativa Nutrition 0.000 title claims abstract description 64
- 235000009566 rice Nutrition 0.000 title claims abstract description 64
- 239000002808 molecular sieve Substances 0.000 title claims abstract description 46
- 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 46
- 238000000034 method Methods 0.000 title claims abstract description 25
- 229910052710 silicon Inorganic materials 0.000 title claims abstract description 25
- 239000010703 silicon Substances 0.000 title claims abstract description 25
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 title claims abstract description 24
- 240000007594 Oryza sativa Species 0.000 title 1
- 241000209094 Oryza Species 0.000 claims abstract description 63
- 239000000843 powder Substances 0.000 claims abstract description 26
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 17
- NBIIXXVUZAFLBC-UHFFFAOYSA-N Phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims abstract description 16
- 238000006243 chemical reaction Methods 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 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 12
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims abstract description 8
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 8
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 8
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims abstract description 8
- VXAUWWUXCIMFIM-UHFFFAOYSA-M aluminum;oxygen(2-);hydroxide Chemical compound [OH-].[O-2].[Al+3] VXAUWWUXCIMFIM-UHFFFAOYSA-M 0.000 claims abstract description 8
- 238000002425 crystallisation Methods 0.000 claims abstract description 8
- 230000008025 crystallization Effects 0.000 claims abstract description 8
- 229910052698 phosphorus Inorganic materials 0.000 claims abstract description 8
- 239000011574 phosphorus Substances 0.000 claims abstract description 8
- 238000005406 washing Methods 0.000 claims abstract description 8
- 238000001027 hydrothermal synthesis Methods 0.000 claims abstract description 6
- 239000010903 husk Substances 0.000 claims abstract description 5
- 238000000197 pyrolysis Methods 0.000 claims description 16
- 238000011282 treatment Methods 0.000 claims description 11
- 238000003756 stirring Methods 0.000 claims description 9
- -1 polytetrafluoroethylene Polymers 0.000 claims description 7
- 229920001343 polytetrafluoroethylene Polymers 0.000 claims description 7
- 239000004810 polytetrafluoroethylene Substances 0.000 claims description 7
- 238000000967 suction filtration Methods 0.000 claims description 6
- 238000002156 mixing Methods 0.000 claims description 4
- 239000000047 product Substances 0.000 claims description 3
- 238000004140 cleaning Methods 0.000 claims description 2
- 125000001664 diethylamino group Chemical group [H]C([H])([H])C([H])([H])N(*)C([H])([H])C([H])([H])[H] 0.000 claims description 2
- 239000012065 filter cake Substances 0.000 claims description 2
- 239000000203 mixture Substances 0.000 claims description 2
- 239000002904 solvent Substances 0.000 claims description 2
- 238000001354 calcination Methods 0.000 claims 1
- HPNMFZURTQLUMO-UHFFFAOYSA-N diethylamine Chemical compound CCNCC HPNMFZURTQLUMO-UHFFFAOYSA-N 0.000 abstract description 6
- 238000001914 filtration Methods 0.000 abstract description 2
- 239000007788 liquid Substances 0.000 abstract 3
- 238000005216 hydrothermal crystallization Methods 0.000 abstract 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 7
- 239000011259 mixed solution Substances 0.000 description 6
- 239000002910 solid waste Substances 0.000 description 5
- 238000005119 centrifugation Methods 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 235000012239 silicon dioxide Nutrition 0.000 description 4
- 239000010457 zeolite Substances 0.000 description 4
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 229910021417 amorphous silicon Inorganic materials 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 3
- 239000000377 silicon dioxide Substances 0.000 description 3
- 238000003786 synthesis reaction Methods 0.000 description 3
- 238000002441 X-ray diffraction Methods 0.000 description 2
- 229910021536 Zeolite Inorganic materials 0.000 description 2
- 239000002253 acid Substances 0.000 description 2
- 230000003197 catalytic effect Effects 0.000 description 2
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 241000196324 Embryophyta Species 0.000 description 1
- 150000007513 acids Chemical class 0.000 description 1
- 239000002154 agricultural waste Substances 0.000 description 1
- 229910001579 aluminosilicate mineral Inorganic materials 0.000 description 1
- 229910021486 amorphous silicon dioxide Inorganic materials 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 210000004027 cell Anatomy 0.000 description 1
- 210000002421 cell wall Anatomy 0.000 description 1
- 235000013339 cereals Nutrition 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000002638 heterogeneous catalyst Substances 0.000 description 1
- 229910001387 inorganic aluminate Inorganic materials 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 238000001000 micrograph Methods 0.000 description 1
- 239000002086 nanomaterial Substances 0.000 description 1
- JRZJOMJEPLMPRA-UHFFFAOYSA-N olefin Natural products CCCCCCCC=C JRZJOMJEPLMPRA-UHFFFAOYSA-N 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- 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
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- 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
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2002/00—Crystal-structural characteristics
- C01P2002/70—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data
- C01P2002/72—Crystal-structural characteristics defined by measured X-ray, neutron or electron diffraction data by d-values or two theta-values, e.g. as X-ray diagram
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/01—Particle morphology depicted by an image
- C01P2004/03—Particle morphology depicted by an image obtained by SEM
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/30—Particle morphology extending in three dimensions
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2004/00—Particle morphology
- C01P2004/60—Particles characterised by their size
- C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Materials Engineering (AREA)
- Silicates, Zeolites, And Molecular Sieves (AREA)
Abstract
The invention discloses a method for preparing an SAPO-34 molecular sieve by using rice husks as silicon sources. The method takes rice hulls as a silicon source and a hard template agent, and synthesizes the SAPO-34 molecular sieve by a hydrothermal method; the method comprises the following specific steps: the method comprises the steps of putting rice hulls in a muffle furnace, pyrolyzing the rice hulls for 3-4 hours at a certain temperature to obtain rice hull ash, preparing a crystallization liquid by using pseudo-boehmite as an aluminum source, phosphoric acid as a phosphorus source and diethylamine as a template agent according to the mass ratio of the aluminum source to the phosphorus source to deionized water to the rice hull ash to the SAPO-34 molecular sieve raw powder of 10:16:60 (5-8) to 10 (0.1-0.3), transferring the crystallization liquid to a reaction kettle, carrying out hydrothermal crystallization, centrifuging, washing, suction filtering and drying the hydrothermal liquid for multiple times to obtain the SAPO-34 molecular sieve product.
Description
Technical Field
The invention belongs to the technical field of inorganic non-metallic material synthesis, and particularly relates to a method for preparing an SAPO-34 molecular sieve by using rice husks as silicon sources.
Background
The zeolite is a crystalline aluminosilicate mineral, sharing SiO by corners4 -And AlO4 -A tetrahedron. Many zeolites have a three-dimensional framework core and cage composed of nanostructures, resulting in a higher specific surface area. Small reactant molecules can diffuse into the microporous system of Zeo and react at internal acid sites. These acids are located in the zeolite boneThe shelves may be size and shape selective catalytic. Thus, zeolites are widely used as heterogeneous catalysts and have played an important role in the chemical industry. The SAPO-34 molecular sieve has an acid center with medium strength and an eight-membered ring microporous structure, and shows excellent catalytic performance in the reaction of preparing low-carbon olefin from methanol.
Rice is a typical silicon-loving plant, and rice hulls contain a large amount of silicon sources. Rice hulls are the largest number of by-products of rice processing and comprise approximately 20% of rice by weight. Worldwide rice production is about 6 million tons per year and produces over 1 million tons of rice hulls. Most agricultural wastes are burned in farmlands or open air, which not only occupies land resources, but also releases a large amount of harmful substances, resulting in environmental pollution. If the rice hulls are reasonably developed and utilized, the problem of environmental pollution can be solved, and a considerable amount of silicon sources can be provided for the development of high and new technology industries. The silicon element in the rice hulls is generally present as amorphous silica, while the silica is in the form of a hydrate (SiO)2·mh2O) is present in the tissues of the rice hulls as one of the components of the cells and cell walls, accounting for 90% -95% of the total silicon content of the rice hulls, while the silicic acid content accounts for 0.5% -0.8% of the total silicon content, and the colloidal silicic acid accounts for 0.00% -0.33%, wherein the silicon of the xylem is present in the form of monosilicic acid. At present, the main focus of development and utilization of rice hull silicon is still how to extract silicon dioxide from rice hulls, and the synthesis of molecular sieves such as A-type molecular sieves and P-type molecular sieves by taking the rice hull silicon as a raw material has been reported.
Chinese patent CN107640775B discloses a method for preparing ZSM-5 molecular sieve by using solid waste, which also takes rice hull ash as a silicon source, but synthesizes high-silicon ZSM-5 molecular sieve.
Disclosure of Invention
Aiming at the defects of the prior art, the invention aims to provide a method for preparing an SAPO-34 molecular sieve by using rice husks as a silicon source; the invention fully adopts the cheap rice hull ash as the silicon source, realizes the flat substitution of the silicon source, can reduce the synthesis cost, and can realize the high added value utilization of the solid waste. The method has the advantages of low raw material price, low requirement on technical equipment, simple operation, uniform product particles, high yield and easy realization of industrialization, and provides reference value for resource utilization of agricultural solid wastes. The CHA-type SAPO-34 molecular sieve synthesized by the method has smaller pore diameter and stronger adaptability to MTO reaction compared with ZSM-5 molecular sieve.
The technical scheme of the invention is specifically introduced as follows.
A method for preparing an SAPO-34 molecular sieve by using rice husks as a silicon source comprises the following specific steps:
(1) pretreatment: cleaning and drying the rice hulls, and putting the rice hulls in a muffle furnace for pyrolysis to obtain rice hull ash;
(2) mixing and pre-crystallizing: mixing an aluminum source, a phosphorus source, rice hull ash, a template agent, deionized water and SAPO-34 molecular sieve raw powder in proportion by taking the rice hull ash as a silicon source and a hard template agent and deionized water as a solvent, and stirring for a certain time;
(3) and (3) crystallization: placing the mixture obtained in the step (2) in a polytetrafluoroethylene reaction kettle for hydrothermal reaction, taking out a product after the reaction is finished, centrifuging, washing, performing suction filtration, and drying a filter cake to obtain SAPO-34 molecular sieve coarse powder;
(4) and (3) post-treatment: and (3) roasting the coarse powder of the SAPO-34 molecular sieve in a muffle furnace at high temperature, and removing a template agent to obtain pure SAPO-34 molecular sieve powder.
In the invention, in the step (1), the drying temperature is 60-80 ℃, the pyrolysis temperature is 400-800 ℃, and the pyrolysis time is 2-5 h. Preferably, the pyrolysis temperature is 500-.
In the present invention, in the step (1), the total mass of the rice hull ash is 100%: si accounts for 80-86wt%, Ca accounts for
9-10wt%, K2-3 wt%, Fe 0.8-1 wt%.
In the invention, in the step (2), an aluminum source is pseudo-boehmite, a phosphorus source is phosphoric acid, and a template agent is diethylamine.
In the invention, in the step (2), the mass ratio of the aluminum source, the phosphorus source, the deionized water, the rice hull ash, the template agent and the SAPO-34 molecular sieve raw powder is 10:16:60 (5-8) to 10 (0.1-0.3).
In the invention, in the step (2), the pre-crystallization stirring time is 2-3 h.
In the invention, in the step (3), the hydrothermal reaction temperature is 195-205 ℃, and the hydrothermal time is 48-72 h.
In the invention, in the step (3), the roasting temperature is 540-.
Compared with the prior art, the invention has the beneficial effects that:
according to the invention, rice hull ash obtained by pyrolyzing rice hulls which are agricultural solid wastes is used as a silicon source and a hard template agent, and the SAPO-34 molecular sieve is prepared by a simple and feasible hydrothermal method, so that resource utilization of the solid wastes can be realized, and certain environmental benefits are achieved;
the experimental operation is simple, the requirement on technical equipment is low, and the prepared SAPO-34 molecular sieve has regular appearance and uniform particle size and is easy to realize industrialization.
Drawings
FIG. 1 is an XRD pattern of rice hull ash obtained by pyrolysis at different temperatures in examples 1 to 5 of the present invention.
FIG. 2 is SEM pictures of parts of rice hull ash obtained by pyrolysis at different temperatures in examples 1 to 5 of the present invention.
FIG. 3 is an SEM photograph of a sample obtained in example 1 of the present invention.
FIG. 4 is an SEM photograph of a portion of a sample obtained in example 1 of the present invention.
Detailed Description
The invention will be further explained in more detail below with reference to the figures and examples, without limiting the scope of the invention thereto.
Example 1
Putting the cleaned and dried rice hulls in a muffle furnace, pyrolyzing the rice hulls at a constant temperature for 4 hours, taking out 5g of the obtained sample, sequentially adding 60g of deionized water, 10g of pseudo-boehmite, 16g of phosphoric acid, 10g of diethylamine and 0.2g of SAPO-34 raw powder, wherein the feeding time interval is 30min, uniformly stirring, transferring the mixed solution into a polytetrafluoroethylene reaction kettle, crystallizing for 48 hours at a temperature of 200 ℃, then carrying out centrifugation, washing, suction filtration, drying and other treatments according to a conventional molecular sieve post-treatment method, collecting, putting the SAPO-34 coarse powder obtained in the above step in the muffle furnace, roasting for 4 hours at a temperature of 550 ℃, and increasing the temperature rate: removing the template agent at 10 ℃/min to obtain SAPO-34 molecular sieve pure powder. FIG. 3 is an SEM photograph of a sample obtained in example 1 of the present invention. FIG. 4 is an SEM photograph of a portion of a sample obtained in example 1 of the present invention. The result shows that the SAPO-34 molecular sieve obtained by the invention has uniform size and is cuboid.
TABLE 1 average particle size of SAPO-34 at different pyrolysis temperatures
Example 2
Putting the cleaned and dried rice hulls in a muffle furnace, pyrolyzing the rice hulls for 2 hours at a constant temperature at 500 ℃, taking out 5g of the obtained sample, sequentially adding 60g of deionized water, 10g of pseudo-boehmite, 16g of phosphoric acid, 10g of diethylamine and 0.2g of SAPO-34 raw powder, wherein the feeding time interval is 30min, uniformly stirring, transferring the mixed solution into a polytetrafluoroethylene reaction kettle at 200 ℃, crystallizing the mixed solution
Dissolving for 72h, then centrifuging, washing, filtering, drying and the like according to a conventional molecular sieve post-treatment method, collecting, placing the SAPO-34 coarse powder obtained in the previous step in a muffle furnace, roasting at 550 ℃ for 4h, and raising the temperature rate: removing the template agent at 10 ℃/min to obtain SAPO-34 molecular sieve pure powder.
Example 3
Putting the cleaned and dried rice hulls in a muffle furnace, pyrolyzing the rice hulls at a constant temperature for 3 hours at 600 ℃, taking out 5g of the obtained sample, sequentially adding 60g of deionized water, 10g of pseudo-boehmite, 16g of phosphoric acid, 10g of diethylamine and 0.2g of SAPO-34 raw powder, wherein the feeding time interval is 30min, uniformly stirring, transferring the mixed solution into a polytetrafluoroethylene reaction kettle for crystallization for 60 hours at 200 ℃, then carrying out centrifugation, washing, suction filtration, drying and other treatments according to a conventional molecular sieve post-treatment method, collecting, putting the SAPO-34 coarse powder obtained in the above step in the muffle furnace for roasting at 550 ℃ for 4 hours, and increasing the temperature rate: removing the template agent at 10 ℃/min to obtain SAPO-34 molecular sieve pure powder.
Example 4
Putting the cleaned and dried rice hulls in a muffle furnace, pyrolyzing the rice hulls at a constant temperature for 4 hours, taking out 5g of the obtained sample, sequentially adding 60g of deionized water, 10g of pseudo-boehmite, 16g of phosphoric acid, 10g of diethylamine and 0.2g of SAPO-34 raw powder, wherein the feeding time interval is 30min, uniformly stirring, transferring the mixed solution into a polytetrafluoroethylene reaction kettle, crystallizing for 72 hours at a temperature of 200 ℃, then carrying out centrifugation, washing, suction filtration, drying and other treatments according to a conventional molecular sieve post-treatment method, collecting, putting the SAPO-34 coarse powder obtained in the above step in the muffle furnace, roasting for 4 hours at a temperature of 550 ℃, and increasing the temperature rate: removing the template agent at 10 ℃/min to obtain SAPO-34 molecular sieve pure powder.
Example 5
Putting the cleaned and dried rice hulls in a muffle furnace, pyrolyzing the rice hulls for 5h at a constant temperature at 800 ℃, taking out 5g of the obtained sample, sequentially adding 60g of deionized water, 10g of pseudo-boehmite, 16g of phosphoric acid, 10g of diethylamine and 0.2g of SAPO-34 raw powder, wherein the feeding time interval is 30min, uniformly stirring, transferring the mixed solution into a polytetrafluoroethylene reaction kettle for crystallization for 72h at 200 ℃, then carrying out centrifugation, washing, suction filtration, drying and other treatments according to a conventional molecular sieve post-treatment method, collecting, putting the SAPO-34 coarse powder obtained in the above step in the muffle furnace for roasting for 4h at 550 ℃, and increasing the temperature rate: removing the template agent at 10 ℃/min to obtain SAPO-34 molecular sieve pure powder.
FIG. 1 is an XRD pattern of rice hull ash obtained by pyrolysis at different temperatures in examples 1-5 of the present invention, and the results show that SAPO-34 molecular sieves with CHA type framework structures were successfully prepared in the examples. FIG. 2 is SEM pictures of parts of rice hull ash obtained by pyrolysis at different temperatures in examples 1 to 5 of the present invention. As is obvious from an electron microscope image, the existence form of amorphous silicon in the rice hull ash obtained by pyrolysis under the condition of 500-700 ℃ is most suitable for preparing the SAPO-34 molecular sieve with better dispersion degree; for rich silicon elements in the rice hulls, the amorphous silicon content in the rice hull ash obtained by pyrolysis at different temperatures is different, the decomposition of other organic matters in the rice hulls is not facilitated due to too low temperature, and amorphous silicon can be changed into silicon dioxide due to too high temperature, so that the activity of silicon is reduced.
The crystallinity and the particle size of the SAPO-34 molecular sieve prepared under different temperature conditions in the embodiment of the invention are obviously different, and the result shows that the content of amorphous silicon dioxide in the rice hull ash obtained by pyrolysis at 600 ℃ is the highest, and the grain size of the molecular sieve obtained by synthesizing the SAPO-34 molecular sieve from the rice hull ash obtained by pyrolysis at the temperature is the smallest.
Claims (8)
1. A method for preparing an SAPO-34 molecular sieve by using rice husks as a silicon source is characterized by comprising the following specific steps:
(1) pretreatment: cleaning and drying the rice hulls, and putting the rice hulls in a muffle furnace for pyrolysis to obtain rice hull ash;
(2) mixing and pre-crystallizing: mixing an aluminum source, a phosphorus source, rice hull ash, a template agent, deionized water and SAPO-34 molecular sieve raw powder in proportion by taking the rice hull ash as a silicon source and a hard template agent and deionized water as a solvent, and stirring for a certain time;
(3) and (3) crystallization: placing the mixture obtained in the step (2) in a polytetrafluoroethylene reaction kettle for hydrothermal reaction, taking out a product after the reaction is finished, centrifuging, washing, performing suction filtration, and drying a filter cake to obtain SAPO-34 molecular sieve coarse powder;
(4) and (3) post-treatment: and (3) roasting the coarse powder of the SAPO-34 molecular sieve in a muffle furnace at high temperature, and removing a template agent to obtain pure SAPO-34 molecular sieve powder.
2. The method as claimed in claim 1, wherein in the step (1), the drying temperature is 60-80 ℃, the pyrolysis temperature is 400-800 ℃, and the pyrolysis time is 2-5 h.
3. The method according to claim 1, wherein in the step (1), the total mass of the rice hull ash is 100%: 80-86wt% of Si, 9-10wt% of Ca, 2-3wt% of K and 0.8-1wt% of Fe.
4. The method of claim 1, wherein in step (2), the aluminum source is pseudoboehmite, the phosphorus source is phosphoric acid, and the templating agent is diethylamine.
5. The method according to claim 4, wherein in the step (2), the mass ratio of the aluminum source, the phosphorus source, the deionized water, the rice hull ash, the template and the SAPO-34 molecular sieve raw powder is 10:16:60 (5-8: 10) (0.1-0.3).
6. The method of claim 1, wherein in step (2), the pre-crystallization stirring time is 2-3 hours.
7. The method of claim 1, wherein in the step (3), the hydrothermal reaction temperature is 195-205 ℃ and the hydrothermal time is 48-72 h.
8. The method as claimed in claim 1, wherein in the step (3), the calcination temperature is 540-.
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| CN116177562A (en) * | 2022-12-05 | 2023-05-30 | 华侨大学 | Method for preparing porous molecular sieve by taking unfired rice hulls as templates |
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|---|---|---|---|---|
| JPS60191018A (en) * | 1984-03-09 | 1985-09-28 | Agency Of Ind Science & Technol | Molecular sieve type zeorite |
| CN103991880A (en) * | 2014-05-30 | 2014-08-20 | 山东理工大学 | Method for preparing mordenite molecular sieve by using rice hull as silicon source |
| CN106379913A (en) * | 2016-08-26 | 2017-02-08 | 曹蕊 | Method for synthesizing P zeolite molecular sieve from rice husk |
| CN108249456A (en) * | 2018-01-23 | 2018-07-06 | 中国石油大学(华东) | A kind of method that grade hole Y type molecular sieve is prepared using rice husk as raw material |
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
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| JPS60191018A (en) * | 1984-03-09 | 1985-09-28 | Agency Of Ind Science & Technol | Molecular sieve type zeorite |
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