CN116553569A - Method for preparing SSZ-13 molecular sieve by transferring L zeolite crystals in mixed alkali system - Google Patents
Method for preparing SSZ-13 molecular sieve by transferring L zeolite crystals in mixed alkali system Download PDFInfo
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- 239000002808 molecular sieve Substances 0.000 title claims abstract description 120
- 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 120
- 239000010457 zeolite Substances 0.000 title claims abstract description 71
- 229910021536 Zeolite Inorganic materials 0.000 title claims abstract description 68
- 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 68
- 239000003513 alkali Substances 0.000 title claims abstract description 65
- 239000013078 crystal Substances 0.000 title claims abstract description 45
- 238000000034 method Methods 0.000 title claims abstract description 29
- 238000002425 crystallisation Methods 0.000 claims abstract description 33
- 230000008025 crystallization Effects 0.000 claims abstract description 32
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 28
- 239000010703 silicon Substances 0.000 claims abstract description 28
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 27
- 238000006243 chemical reaction Methods 0.000 claims abstract description 23
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 22
- GNUJKXOGRSTACR-UHFFFAOYSA-M 1-adamantyl(trimethyl)azanium;hydroxide Chemical compound [OH-].C1C(C2)CC3CC2CC1([N+](C)(C)C)C3 GNUJKXOGRSTACR-UHFFFAOYSA-M 0.000 claims abstract description 18
- 239000000843 powder Substances 0.000 claims abstract description 18
- 238000001035 drying Methods 0.000 claims abstract description 16
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 99
- 238000003756 stirring Methods 0.000 claims description 54
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 29
- 239000008367 deionised water Substances 0.000 claims description 28
- 229910021641 deionized water Inorganic materials 0.000 claims description 28
- 239000000047 product Substances 0.000 claims description 28
- 229940073455 tetraethylammonium hydroxide Drugs 0.000 claims description 28
- LRGJRHZIDJQFCL-UHFFFAOYSA-M tetraethylazanium;hydroxide Chemical compound [OH-].CC[N+](CC)(CC)CC LRGJRHZIDJQFCL-UHFFFAOYSA-M 0.000 claims description 28
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 21
- UNYSKUBLZGJSLV-UHFFFAOYSA-L calcium;1,3,5,2,4,6$l^{2}-trioxadisilaluminane 2,4-dioxide;dihydroxide;hexahydrate Chemical compound O.O.O.O.O.O.[OH-].[OH-].[Ca+2].O=[Si]1O[Al]O[Si](=O)O1.O=[Si]1O[Al]O[Si](=O)O1 UNYSKUBLZGJSLV-UHFFFAOYSA-L 0.000 claims description 19
- 229910052676 chabazite Inorganic materials 0.000 claims description 19
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical group O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 15
- 238000005406 washing Methods 0.000 claims description 15
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 14
- WGTYBPLFGIVFAS-UHFFFAOYSA-M tetramethylammonium hydroxide Chemical compound [OH-].C[N+](C)(C)C WGTYBPLFGIVFAS-UHFFFAOYSA-M 0.000 claims description 12
- 239000006229 carbon black Substances 0.000 claims description 11
- 239000012467 final product Substances 0.000 claims description 11
- 239000000499 gel Substances 0.000 claims description 9
- 239000007787 solid Substances 0.000 claims description 9
- 150000007529 inorganic bases Chemical class 0.000 claims description 7
- LPSKDVINWQNWFE-UHFFFAOYSA-M tetrapropylazanium;hydroxide Chemical compound [OH-].CCC[N+](CCC)(CCC)CCC LPSKDVINWQNWFE-UHFFFAOYSA-M 0.000 claims description 6
- 238000005216 hydrothermal crystallization Methods 0.000 claims description 5
- 150000007530 organic bases Chemical class 0.000 claims description 5
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 claims description 4
- 239000000741 silica gel Substances 0.000 claims description 4
- 229910002027 silica gel 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
- 239000000463 material Substances 0.000 claims description 3
- 230000007935 neutral effect Effects 0.000 claims description 3
- 235000019353 potassium silicate Nutrition 0.000 claims description 3
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 3
- 238000002360 preparation method Methods 0.000 abstract description 6
- 230000000694 effects Effects 0.000 abstract description 3
- 238000000926 separation method Methods 0.000 abstract description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 16
- 239000000203 mixture Substances 0.000 description 13
- -1 benzyltrimethylamine ion Chemical class 0.000 description 12
- 239000012071 phase Substances 0.000 description 12
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 11
- 239000004810 polytetrafluoroethylene Substances 0.000 description 11
- 238000010791 quenching Methods 0.000 description 11
- 230000000171 quenching effect Effects 0.000 description 11
- 229910001220 stainless steel Inorganic materials 0.000 description 11
- 239000010935 stainless steel Substances 0.000 description 11
- 239000012258 stirred mixture Substances 0.000 description 11
- 230000000052 comparative effect Effects 0.000 description 10
- 238000002441 X-ray diffraction Methods 0.000 description 9
- 230000006872 improvement Effects 0.000 description 9
- 230000015572 biosynthetic process Effects 0.000 description 7
- 238000003786 synthesis reaction Methods 0.000 description 7
- 239000007789 gas Substances 0.000 description 5
- 230000002194 synthesizing effect Effects 0.000 description 5
- 238000001000 micrograph Methods 0.000 description 4
- 238000001878 scanning electron micrograph Methods 0.000 description 4
- 238000012546 transfer Methods 0.000 description 4
- 230000009466 transformation Effects 0.000 description 4
- CSDREXVUYHZDNP-UHFFFAOYSA-N alumanylidynesilicon Chemical compound [Al].[Si] CSDREXVUYHZDNP-UHFFFAOYSA-N 0.000 description 3
- 239000003054 catalyst Substances 0.000 description 3
- 230000003197 catalytic effect Effects 0.000 description 3
- 238000009776 industrial production Methods 0.000 description 3
- 229910052757 nitrogen Inorganic materials 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 239000011148 porous material Substances 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- 239000011959 amorphous silica alumina Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000010531 catalytic reduction reaction Methods 0.000 description 2
- 150000001768 cations Chemical class 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- 238000005342 ion exchange Methods 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 239000007790 solid phase Substances 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 238000011426 transformation method Methods 0.000 description 2
- PAWQVTBBRAZDMG-UHFFFAOYSA-N 2-(3-bromo-2-fluorophenyl)acetic acid Chemical compound OC(=O)CC1=CC=CC(Br)=C1F PAWQVTBBRAZDMG-UHFFFAOYSA-N 0.000 description 1
- 239000001763 2-hydroxyethyl(trimethyl)azanium Substances 0.000 description 1
- QGZKDVFQNNGYKY-UHFFFAOYSA-O Ammonium Chemical compound [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 description 1
- 235000019743 Choline chloride Nutrition 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- JPVYNHNXODAKFH-UHFFFAOYSA-N Cu2+ Chemical group [Cu+2] JPVYNHNXODAKFH-UHFFFAOYSA-N 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- ZJOKNSFTHAWVKK-UHFFFAOYSA-K aluminum octadecanoate sulfate Chemical compound C(CCCCCCCCCCCCCCCCC)(=O)[O-].[Al+3].S(=O)(=O)([O-])[O-] ZJOKNSFTHAWVKK-UHFFFAOYSA-K 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 229910021417 amorphous silicon Inorganic materials 0.000 description 1
- 229960003178 choline chloride Drugs 0.000 description 1
- SGMZJAMFUVOLNK-UHFFFAOYSA-M choline chloride Chemical compound [Cl-].C[N+](C)(C)CCO SGMZJAMFUVOLNK-UHFFFAOYSA-M 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 229910001431 copper ion Inorganic materials 0.000 description 1
- XTVVROIMIGLXTD-UHFFFAOYSA-N copper(II) nitrate Chemical compound [Cu+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O XTVVROIMIGLXTD-UHFFFAOYSA-N 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000012634 fragment Substances 0.000 description 1
- 231100000086 high toxicity Toxicity 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- JJWLVOIRVHMVIS-UHFFFAOYSA-N isopropylamine Chemical compound CC(C)N JJWLVOIRVHMVIS-UHFFFAOYSA-N 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000007873 sieving Methods 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 239000007858 starting material Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
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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
- C01B39/02—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof; Direct preparation thereof; Preparation thereof starting from a reaction mixture containing a crystalline zeolite of another type, or from preformed reactants; After-treatment thereof
- C01B39/04—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof; Direct preparation thereof; Preparation thereof starting from a reaction mixture containing a crystalline zeolite of another type, or from preformed reactants; After-treatment thereof using at least one organic template directing agent, e.g. an ionic quaternary ammonium compound or an aminated compound
-
- 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
- C01P2004/60—Particles characterised by their size
- C01P2004/62—Submicrometer sized, i.e. from 0.1-1 micrometer
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P30/00—Technologies relating to oil refining and petrochemical industry
- Y02P30/40—Ethylene production
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- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Materials Engineering (AREA)
- Inorganic Chemistry (AREA)
- Silicates, Zeolites, And Molecular Sieves (AREA)
Abstract
The invention relates to the field of preparation of SSZ-13 molecular sieves, in particular to a method for preparing an SSZ-13 molecular sieve by transferring L zeolite crystals in a mixed alkali system, wherein inorganic alkali, organic alkali and a template agent N, N, N-trimethyl-1-adamantylammonium hydroxide are fully stirred; then adding a silicon source to form uniform sol; adding L zeolite and a small amount of seed crystal to prepare molecular sieve crystallization initial gel, transferring the molecular sieve crystallization initial gel to a hydrothermal high-pressure reaction kettle, performing centrifugal separation after crystallization, drying to obtain molecular sieve raw powder, and roasting to obtain SSZ-13 molecular sieve crystallization product. The invention synthesizes the SSZ-13 molecular sieve by using L zeolite to convert crystals, and improves the crystallization rate through the regulation and control of crystallization dynamics; the mixed alkali system is formed by using the organic alkali and the inorganic alkali, the consumption of the expensive template agent N, N, N-trimethyl-1-adamantyl ammonium hydroxide can be reduced, and the addition of the organic alkali has a good regulation and control effect on the physicochemical properties of the synthesized SSZ-13 product.
Description
Technical Field
The invention relates to the field of preparation of SSZ-13 molecular sieves, in particular to a method for preparing an SSZ-13 molecular sieve by converting L zeolite in a mixed alkali system.
Background
Molecular sieves are widely used because of their regular pore structure and large specific surface area. Wherein, the small pore SSZ-13 molecular sieve with Chabazite (CHA) topological structure has an ellipsoidal (0.67 nm multiplied by 1.0 nm) crystal structure containing an eight-membered ring window (0.38 nm multiplied by 0.38 nm) and a three-dimensional crossed pore canal structure. Due to its unique microporous structure, good hydrothermal stability, rich ion exchange sites and suitable acidity, the selective catalytic reduction of nitrogen oxides (NH 3 The catalyst has great application potential in the fields of SCR), methanol-to-olefin (MTO), gas adsorption separation and the like.
SSZ-13 molecular sieves are typically synthesized by hydrothermal crystallization using an amorphous silicon source and an aluminum source as starting materials, water as a solvent, an inorganic base as a mineralizer, and N, N, N-trimethyl-1-adamantylammonium hydroxide (TMAdaOH) as an organic template. However, the method generally has the problems of high price of the template agent, large consumption, high synthesis cost, long crystallization time, high energy consumption, low solid yield and the like, and the obtained molecular sieve has large size and limited mass transfer. Therefore, the method for preparing the small-size molecular sieve with high mass transfer efficiency by using the method with low consumption of the development template agent, low cost, high crystallization rate and high solid phase yield has very important significance for large-scale popularization and application of SSZ-13.
Compared with the traditional hydrothermal crystallization method, the crystallization time can be shortened by the crystal transformation method which has been paid attention in recent years, and the consumption of the template agent is also reduced. This is mainly due to the fact that the starting zeolite material is degraded by the inorganic base mineralizer to produce some nanostructured fragments or secondary building blocks which rapidly core grow under the direction of the organic template structure, assembling with high selectivity into specific target zeolites. In addition, the synthetic strategies of zeolites can have a great impact on their structure and performance. At present, the SSZ-13 molecular sieve is synthesized by adopting a crystal transformation method, and FAU type zeolite is mainly used as parent zeolite for crystal transformation synthesis. In addition, LTA-type zeolite, P-type zeolite, LEV-type zeolite, BEA-type, MFI-type, LTL-type and FER have been reportedThe zeolite is N, N, N-trimethyl-1-adamantane ammonium (TMDa) + ) As a structure directing agent, the CHA-type zeolite product was synthesized. However, the template is expensive, which makes the cost of synthesizing SSZ-13 high. Based on this, researchers have used benzyltrimethylamine ion, N-alkyl-1, 4-diazabicyclooctane cation, polycycloalkylamine cation, N-dimethylpiperidine and choline chloride, which are relatively low in price, as a template agent to reduce the synthesis cost, but there are problems such as high toxicity, large amount of the template agent, narrow synthesis phase region, long crystallization time, low solid phase yield and the like.
Patent CN105236441a reports a method of synthesizing CHA by FAU-type USY molecular sieve using tetraethylammonium hydroxide (TEAOH) mixed with N, N-trimethyl-1-adamantylammonium hydroxide (TMAdaOH) as a template agent, but the crystallization time is as long as 3-7d, which is disadvantageous for industrial production; patent CN114772610A discloses a method for efficiently and rapidly synthesizing H-SSZ-13 molecular sieve by adopting TEAOH and other expensive TMAHaOH as an organic template agent, adopting sodium-free cation source to replace inorganic alkali such as NaOH and adopting a solvent-free auxiliary crystallization method, and the synthetic target molecular sieve has a narrower silicon-aluminum ratio range (SiO although the synthetic efficiency is high 2 :Al 2 O 3 Only 10-30); patent CN108059172A discloses a preparation method of an H-SSZ-13 molecular sieve, which adopts TMAHaOH as a main template agent and TEAOH, isopropylamine and the like as auxiliary template agents and alcohols and the like as auxiliary solvents for synthesis, but the actual process conditions are complex; patent CN107758691B discloses that TMADAOH is used as a template in an inorganic alkali system, and L zeolite topology is used for reconstructing and synthesizing a high-silicon CHA type SSZ-13 molecular sieve, and the preparation system has a wide silicon-aluminum ratio range, but the template agent dosage is still large, the crystallization time is still long, and the large-scale production and the application of the SSZ-13 molecular sieve are not facilitated.
Disclosure of Invention
Aiming at the defects existing in the prior art, the invention aims to provide a method for preparing an SSZ-13 molecular sieve by converting L zeolite in a mixed alkali system. The preparation method provided by the invention has the advantages of simple operation, short crystallization time, less consumption of expensive template agent, low cost and wide synthetic phase area, and is beneficial to industrial production; and the synthesized SSZ-13 molecular sieve product has the advantages of high crystallinity, good purity, high solid yield, small crystal size, contribution to rapid mass transfer, improvement of the application performance of the molecular sieve and the like.
The invention is realized by the following technical scheme: a method for preparing SSZ-13 molecular sieve by transferring L zeolite crystal in a mixed alkali system comprises the following steps:
(1) Preparing molecular sieve crystallization starting gel: at room temperature, dissolving inorganic alkali into deionized water, then sequentially adding an organic alkali solution and a template agent N, N, N-trimethyl-1-adamantyl ammonium hydroxide solution, and fully stirring to obtain a uniform solution; then adding a silicon source under stirring to form uniform sol; adding L zeolite, continuously stirring, adding a small amount of seed crystal, and fully stirring to obtain uniform molecular sieve crystallization starting gel; wherein the total silicon is silicon source and SiO contained in the L zeolite 2 Calculated as Al contained in L zeolite 2 O 3 The molar ratio range of the reaction materials is as follows, calculated by inorganic base as A, calculated by organic base as B and calculated by template agent as R: siO (SiO) 2 :Al 2 O 3 :A:B:R:H 2 O＝1:(0.00167～0.0333):(0.05～0.3):(0.05～0.4):(0.03～0.1):(10～20)；
(2) And (3) hydrothermal crystallization: transferring the molecular sieve crystallization initial gel prepared in the first step into a hydrothermal high-pressure reaction kettle, crystallizing at 150-180 ℃ for 4-48 h, centrifuging after crystallization, washing with deionized water to be neutral, and drying to obtain molecular sieve raw powder;
(3) High-temperature roasting: roasting the molecular sieve raw powder obtained in the step (2) in air at 550-600 ℃ for 6-10 h to obtain a final product SSZ-13 molecular sieve crystallization product.
As a further improvement of the technical scheme of the invention, the inorganic base is sodium hydroxide or potassium hydroxide.
As a further improvement of the technical scheme of the invention, the organic base is tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide or tetrapropyl ammonium hydroxide.
As a further improvement of the technical scheme of the invention, the silicon source is white carbon black, solid silica gel, silica sol, water glass or tetraethoxysilane.
As a further improvement of the technical scheme of the invention, the L zeolite is NaK type L zeolite, NH 4 Form L zeolite or H form L zeolite.
As a further improvement of the technical scheme of the invention, the seed crystal is 0.3-3% of the total mass of the silicon source.
As a further improvement of the technical scheme of the invention, the seed crystal is SSZ-13 molecular sieve or SAPO-34 molecular sieve with chabazite crystal phase.
As a further improvement of the technical scheme of the invention, the grain size of the SSZ-13 molecular sieve crystallization product is 100-500nm.
Compared with the prior art, the technical scheme provided by the invention has the following advantages: the invention synthesizes the SSZ-13 molecular sieve by using L zeolite to convert crystals, and improves the crystallization rate by promoting crystallization kinetics; meanwhile, a mixed alkali system is formed by utilizing organic alkali and inorganic alkali, the consumption of an expensive template agent N, N, N-trimethyl-1-adamantyl ammonium hydroxide can be greatly reduced, and the addition of the organic alkali has a good regulation and control effect on physicochemical properties (grain size, specific surface area, crystallinity, silicon-aluminum ratio and the like) of a synthesized SSZ-13 product. The preparation method of the L zeolite crystal transformation in the mixed alkali system has the advantages of simple operation, short crystallization time, less consumption of expensive template agent, low synthesis cost and wide synthesis phase area, and is beneficial to industrial production; and the synthesized SSZ-13 molecular sieve product has the advantages of high crystallinity, good purity, high solid yield, small crystal size, contribution to rapid mass transfer, improvement of the application performance of the molecular sieve and the like. Further research has found that after the SSZ-13 molecular sieve prepared by the invention is loaded with metallic copper, the molecular sieve is used in ammonia selective catalytic reduction (NH 3 -SCR) shows excellent catalytic performance in the reaction.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and together with the description, serve to explain the principles of the invention.
In order to more clearly illustrate the embodiments of the invention or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, and it will be obvious to a person skilled in the art that other drawings can be obtained from these drawings without inventive effort.
FIG. 1 shows XRD patterns of the products of examples 1 to 8 in the present invention.
FIG. 2 shows XRD patterns of the products of comparative examples 1 to 3 in the present invention.
FIG. 3 is a scanning electron microscope image of the product prepared in example 1 of the present invention.
FIG. 4 is a scanning electron microscope image of the product prepared in example 2 of the present invention.
FIG. 5 is a scanning electron microscope image of the product prepared in example 3 of the present invention.
FIG. 6 is a scanning electron microscope image of the product prepared in example 4 of the present invention.
FIG. 7 is a schematic representation of NH for NOx after copper ion exchange using SSZ-13 molecular sieves prepared in examples 1 and 2 and comparative examples 2 and 3 of the present disclosure 3 -catalytic performance map of SCR reaction. It can be seen that: SSZ-13 molecular sieves synthesized from amorphous silica alumina sources (comparative example 2), and a single template of TMAHaOH and higher template dosage (TMAHaOH/SiO 2 Compared with the SSZ-13 molecular sieve (comparative example 3) prepared under the condition of the molar ratio of 0.2), the molecular sieve prepared by the method disclosed by the invention has better low-temperature catalytic activity and wider activity temperature window.
Detailed Description
In order that the above objects, features and advantages of the invention will be more clearly understood, a further description of the invention will be made. It should be noted that, without conflict, the embodiments of the present invention and features in the embodiments may be combined with each other.
In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention, but the present invention may be practiced otherwise than as described herein; it will be apparent that the embodiments in the specification are only some, but not all, embodiments of the invention.
The invention provides a specific embodiment of a method for preparing an SSZ-13 molecular sieve by converting L zeolite in a mixed alkali system, which comprises the following steps:
(1) Preparing molecular sieve crystallization starting gel: at room temperature, dissolving inorganic alkali into deionized water, then sequentially adding an organic alkali solution and a template agent N, N, N-trimethyl-1-adamantyl ammonium hydroxide solution, and fully stirring to obtain a uniform solution; then adding a silicon source under stirring to form uniform sol; adding L zeolite, continuously stirring, adding a small amount of seed crystal, and fully stirring to obtain uniform molecular sieve crystallization starting gel; wherein the total silicon is silicon source and SiO contained in the L zeolite 2 Calculated as Al contained in L zeolite 2 O 3 The molar ratio range of the reaction materials is as follows, calculated by inorganic base as A, calculated by organic base as B and calculated by template agent as R: siO (SiO) 2 :Al 2 O 3 :A:B:R:H 2 O＝1:(0.00167～0.0333):(0.05～0.3):(0.05～0.4):(0.03～0.1):(10～20)；
(2) And (3) hydrothermal crystallization: transferring the molecular sieve crystallization initial gel prepared in the first step into a hydrothermal high-pressure reaction kettle, crystallizing at 150-180 ℃ for 4-48 h, centrifuging after crystallization, washing with deionized water to be neutral, and drying to obtain molecular sieve raw powder;
(3) High-temperature roasting: roasting the molecular sieve raw powder obtained in the step (2) in air at 550-600 ℃ for 6-10 h to obtain a final product SSZ-13 molecular sieve crystallization product.
In one embodiment provided by the present invention, the inorganic base is sodium hydroxide or potassium hydroxide.
In another embodiment provided by the present invention, the organic base is tetramethylammonium hydroxide, tetraethylammonium hydroxide, or tetrapropylammonium hydroxide.
In one embodiment of the present invention, the silicon source is white carbon black, solid silica gel, silica sol, water glass or ethyl orthosilicate.
In another embodiment of the present invention, the L zeolite is NaK type L zeolite, NH 4 Form L zeolite or H form L zeolite.
In one embodiment provided by the invention, the seed crystal is 0.3-3% of the total mass of the silicon source.
In another embodiment provided by the present invention, the seed is an SSZ-13 molecular sieve or a SAPO-34 molecular sieve having a Chabazite (CHA) crystal phase.
In one embodiment provided by the invention, the SSZ-13 molecular sieve crystallized product has a grain size of 100-500nm.
Specific embodiments of the present invention are described in detail below.
Example 1
In a mixed alkali system of organic alkali tetraethylammonium hydroxide and inorganic alkali sodium hydroxide, NH 4 The L zeolite is transformed into the CHA type SSZ-13 molecular sieve, which comprises the following steps:
6.98g of N, N, N-trimethyl-1-adamantylammonium hydroxide solution (TMAGAOH, 25 wt.%), 32g of deionized water and 1.38g of sodium hydroxide (NaOH, 96 wt.%), 9.72g of tetraethylammonium hydroxide (TEAOH, 25 wt.%) were mixed in a beaker with stirring at room temperature until clear, followed by slow addition of 9.15g of white carbon black (SiO 2 92 wt%) after vigorous stirring for 2h, NH was added to the continuously stirred mixture 4 L zeolite 1.91g (SiO 2 /Al 2 O 3 =6), after stirring for 1h, 0.2g of calcined SSZ-13 seed crystal accounting for 2% of the total mass of the silicon source was finally added, and stirring was vigorously performed at room temperature for 1h, and the above mixture was transferred to a stainless steel reaction kettle with polytetrafluoroethylene lining. Crystallizing at 160 ℃ for 12 hours, taking out, quenching to room temperature, washing to neutrality by deionized water, drying at 80 ℃, and roasting in air at 550 ℃ for 6 hours to obtain the final product molecular sieve powder.
FIG. 1 shows the XRD pattern of SSZ-13 molecular sieve, and shows that the synthesized product is pure phase SSZ-13 molecular sieve with seed crystal as reference and relative crystallinity of 100.87%. FIG. 3 is an SEM image of the resulting SSZ-13 molecular sieve, from which it can be seen that the synthesized molecular sieve has a cubic morphology, with dimensions of about 300-500nm.
Example 2
In a mixed alkali system of organic alkali tetraethylammonium hydroxide and inorganic alkali sodium hydroxide, NH 4 The L zeolite is transformed into the CHA type SSZ-13 molecular sieve, which comprises the following steps:
6.98g of N, N, N-trimethyl-1-adamantylammonium hydroxide solution (TMAGAOH, 25wt% with stirring at RTIn a beaker, 5.57g deionized water and 1.38g sodium hydroxide (NaOH, 96 wt%), 29.16g tetraethylammonium hydroxide (TEAOH, 25 wt%) were mixed and stirred until clear, followed by a slow addition of 9.15g white carbon black (SiO) 2 92 wt%) after vigorous stirring for 2h, NH was added to the continuously stirred mixture 4 L zeolite 1.91g (SiO 2 /Al 2 O 3 =6), after stirring for 1h, 0.2g of calcined SSZ-13 seed crystal accounting for 2% of the total mass of the silicon source was finally added, and stirring was vigorously performed at room temperature for 1h, and the above mixture was transferred to a stainless steel reaction kettle with polytetrafluoroethylene lining. Crystallizing at 160 ℃ for 15 hours, taking out, quenching to room temperature, washing to neutrality by deionized water, drying at 100 ℃, and roasting in air at 550 ℃ for 8 hours to obtain the final product molecular sieve powder.
FIG. 1 is an XRD pattern for an SSZ-13 molecular sieve, showing that the synthesized product is a pure phase SSZ-13 molecular sieve with seed crystals as a reference, and the relative crystallinity is 95.75%. FIG. 4 is an SEM image of the resulting SSZ-13 molecular sieve, from which it can be seen that the synthesized molecular sieve has a cubic morphology, with dimensions of about 100-150nm.
Example 3
In a mixed alkali system of organic alkali tetraethylammonium hydroxide and inorganic alkali sodium hydroxide, the HL zeolite is subjected to crystal transformation to synthesize the CHA type SSZ-13 molecular sieve, and the method comprises the following steps of:
5.58g of N, N, N-trimethyl-1-adamantylammonium hydroxide solution (TMAGAOH, 25 wt.%), 21.20g of deionized water and 2.07g of sodium hydroxide (NaOH, 96 wt.%), 9.72g of tetraethylammonium hydroxide (TEAOH, 25 wt.%) were mixed in a beaker with stirring until clear, followed by slow addition of 8.61g of white carbon black (SiO) 2 92 wt%) of HL zeolite was added to the continuously stirred mixture after vigorous stirring for 2h (SiO) 2 /Al 2 O 3 =6), after stirring for 1h, 0.2g of calcined SSZ-13 seed crystal accounting for 2% of the total mass of the silicon source was finally added, and stirring was vigorously performed at room temperature for 1h, and the above mixture was transferred to a stainless steel reaction kettle with polytetrafluoroethylene lining. Crystallizing for 4 hours at 180 ℃, taking out, quenching to room temperature, washing to neutrality by deionized water, drying at 80 ℃, and roasting in air at 550 ℃ for 6 hours to obtain the final product molecular sieve powder.
FIG. 1 is an XRD pattern of SSZ-13 molecular sieve, showing that the synthesized product is pure phase SSZ-13 molecular sieve, and the relative crystallinity is 92.01% by taking seed crystal as reference. FIG. 5 is an SEM image of the resulting SSZ-13 molecular sieve, from which it can be seen that the synthesized molecular sieve has a cubic morphology, with dimensions of about 150-200nm.
Example 4
In a mixed alkali system of organic alkali tetraethylammonium hydroxide and inorganic alkali sodium hydroxide, NH 4 The L zeolite is transformed into the CHA type SSZ-13 molecular sieve, which comprises the following steps:
4.19g of N, N, N-trimethyl-1-adamantylammonium hydroxide solution (TMAGAOH, 25 wt.%), 14.95g of deionized water and 2.07g of sodium hydroxide (NaOH, 96 wt.%), 19.44g of tetraethylammonium hydroxide (TEAOH, 25 wt.%) were mixed in a beaker with stirring until clear, followed by slow addition of 9.15g of white carbon black (SiO) 2 92 wt%) after vigorous stirring for 2h, NH was added to the continuously stirred mixture 4 L zeolite 1.91g (SiO 2 /Al 2 O 3 =6), after stirring for 1h, 0.3g of calcined SSZ-13 seed crystal accounting for 3% of the total mass of the silicon source was finally added, and stirring was vigorously performed at room temperature for 1h, and the above mixture was transferred to a stainless steel reaction kettle with polytetrafluoroethylene lining. Crystallizing at 160 ℃ for 18 hours, taking out, quenching to room temperature, washing to neutrality by deionized water, drying at 80 ℃, and roasting in air at 550 ℃ for 8 hours to obtain the final product molecular sieve powder.
FIG. 1 shows the XRD pattern of SSZ-13 molecular sieve, and shows that the synthesized product is pure phase SSZ-13 molecular sieve with seed crystal as reference and relative crystallinity of 89.72%. FIG. 6 is an SEM image of the resulting SSZ-13 molecular sieve, from which it can be seen that the synthesized molecular sieve has a cubic morphology, with dimensions of about 150-200nm.
Example 5
In a mixed alkali system of organic alkali tetramethyl ammonium hydroxide and inorganic alkali potassium hydroxide, naKL zeolite is subjected to crystal transformation to synthesize the CHA type SSZ-13 molecular sieve, and the method comprises the following steps of:
10.47g of N, N, N-trimethyl-1-adamantylammonium hydroxide solution (TMAGAOH, 25 wt.%), 41g of deionized water and 1.95g of potassium hydroxide (KOH, 95 wt.%) 6.02g of tetramethylammonium hydroxide (TMAOH, 25 wt.%) were stirred at room temperatureMix in beaker and stir to clear, followed by slow addition of 8.5g solid silica gel (SiO 2 99 wt%) of NaKL zeolite was added to the continuously stirred mixture after vigorous stirring for 2h (SiO) 2 /Al 2 O 3 =6), stirring for 1h, adding 0.05g of calcined SSZ-13 seed crystal accounting for 0.5% of the total mass of the silicon source, stirring vigorously at room temperature for 1h, and transferring the mixture into a stainless steel reaction kettle with a polytetrafluoroethylene lining. Crystallizing at 170 ℃ for 8 hours, taking out, quenching to room temperature, washing to neutrality by deionized water, drying at 80 ℃, and roasting in air at 580 ℃ for 6 hours to obtain the final product molecular sieve powder. The obtained SSZ-13 molecular sieve has good purity, high crystallinity and size of about 300-400nm.
Example 6
In a mixed alkali system of organic alkali tetrapropylammonium hydroxide and inorganic alkali sodium hydroxide, NH 4 The L zeolite is transformed into the CHA type SSZ-13 molecular sieve, which comprises the following steps:
8.376g of N, N, N-trimethyl-1-adamantylammonium hydroxide solution (TMAGAOH, 25 wt.%), 18.14g of deionized water and 1.38g of potassium hydroxide (NaOH, 96 wt.%), 26.84g of tetrapropylammonium hydroxide (TPAOH, 25 wt.%) were mixed in a beaker with stirring until clear, followed by slow addition of 29.22g of ethyl orthosilicate (SiO) 2 28.8 wt%) after vigorous stirring for 2h, NH was added to the continuously stirred mixture 4 L zeolite 1.91g (SiO 2 /Al 2 O 3 =6), stirring for 1h, adding 0.1g of calcined SSZ-13 seed crystal accounting for 1% of the total mass of the silicon source, stirring vigorously at room temperature for 1h, and transferring the mixture into a stainless steel reaction kettle with a polytetrafluoroethylene lining. Crystallizing at 160 ℃ for 18 hours, taking out, quenching to room temperature, washing to neutrality by deionized water, drying at 80 ℃, and roasting in air at 580 ℃ for 8 hours to obtain the final product molecular sieve powder. The obtained SSZ-13 molecular sieve has good purity, high crystallinity and size of about 350-450nm.
Example 7
In a mixed alkali system of organic alkali tetraethylammonium hydroxide and inorganic alkali sodium hydroxide, NH 4 The L zeolite is transformed into the CHA type SSZ-13 molecular sieve, which comprises the following steps:
stirring at room temperature6.98g of N, N, N-trimethyl-1-adamantylammonium hydroxide solution (TMAGAOH, 25 wt%), 24.74g of deionized water and 1.38g of sodium hydroxide (NaOH, 96 wt%), 19.44g of tetraethylammonium hydroxide (TEAOH, 25 wt%) were mixed in a beaker and stirred until clear, followed by slow addition of 24.26g of silica sol (SiO 2 40% by mass) and vigorously stirring for 2 hours, then adding NH to the continuously stirred mixture 4 L zeolite 0.254g (SiO 2 /Al 2 O 3 =6), after stirring for 1h, 0.2g of calcined SSZ-13 seed crystal accounting for 2% of the total mass of the silicon source was finally added, and stirring was vigorously performed at room temperature for 1h, and the above mixture was transferred to a stainless steel reaction kettle with polytetrafluoroethylene lining. Crystallizing at 160 ℃ for 15h, taking out, quenching to room temperature, washing to neutrality by deionized water, drying at 80 ℃, and roasting in air at 550 ℃ for 10h to obtain the final product molecular sieve powder. The obtained SSZ-13 molecular sieve has good purity, high crystallinity and size of about 300-400nm.
Example 8
In a mixed alkali system of organic alkali tetraethylammonium hydroxide and inorganic alkali sodium hydroxide, NH 4 The L zeolite is transformed into the CHA type SSZ-13 molecular sieve, which comprises the following steps:
6.98g of N, N, N-trimethyl-1-adamantylammonium hydroxide solution (TMAGAOH, 25 wt.%), 32g of deionized water and 1.38g of sodium hydroxide (NaOH, 96 wt.%), 9.72g of tetraethylammonium hydroxide (TEAOH, 25 wt.%) were mixed in a beaker with stirring at room temperature until clear, followed by slow addition of 10.65g of white carbon black (SiO 2 92 wt%) after vigorous stirring for 2h, NH was added to the continuously stirred mixture 4 L zeolite 0.127g (SiO 2 /Al 2 O 3 =6), after stirring for 1h, 0.2g of calcined SAPO-34 seed crystals accounting for 2% of the total mass of the silicon source were finally added, and stirring was vigorously performed at room temperature for 1h, and the above mixture was transferred to a stainless steel reaction kettle with polytetrafluoroethylene lining. Crystallizing at 160 ℃ for 12 hours, taking out, quenching to room temperature, washing to neutrality by deionized water, drying at 100 ℃, and roasting in air at 600 ℃ for 6 hours to obtain the final product molecular sieve powder. The obtained SSZ-13 molecular sieve has good purity, high crystallinity and size of about 350-450nm.
Comparative example 1
In an inorganic alkali sodium hydroxide system, NH is carried out under the condition of low TMA DaOH consumption 4 The L zeolite is transformed into the CHA type SSZ-13 molecular sieve, which comprises the following steps:
6.98g of N, N, N-trimethyl-1-adamantylammonium hydroxide solution (TMAGAOH, 25 wt.%), 39.32g of deionized water and 1.38g of sodium hydroxide (NaOH, 96 wt.%) were mixed in a beaker with stirring at room temperature and stirred until clear, followed by slow addition of 9.15g of white carbon black (SiO 2 92 wt%) after vigorous stirring for 2h, NH was added to the continuously stirred mixture 4 L zeolite 1.91g (SiO 2 /Al 2 O 3 =6), after stirring for 1h, 0.2g of calcined SSZ-13 seed crystal accounting for 2% of the total mass of the silicon source was finally added, and stirring was vigorously performed at room temperature for 1h, and the above mixture was transferred to a stainless steel reaction kettle with polytetrafluoroethylene lining. Crystallizing at 160 ℃ for 24 hours, taking out, quenching to room temperature, washing to neutrality by deionized water, drying at 80 ℃, and roasting in air at 550 ℃ for 6 hours to obtain the product molecular sieve powder.
FIG. 2 is an XRD pattern of the resulting product, from which it can be seen that the pure phase SSZ-13 molecular sieve was not successfully synthesized.
Comparative example 2
In a mixed alkali system of organic alkali tetraethylammonium hydroxide and inorganic alkali sodium hydroxide, synthesizing the CHA type SSZ-13 molecular sieve by an amorphous silica-alumina source, and comprises the following steps of:
6.98g of N, N, N-trimethyl-1-adamantylammonium hydroxide solution (TMAGAOH, 25 wt.%), 32g of deionized water and 1.38g of sodium hydroxide (NaOH, 96 wt.%), 9.72g of tetraethylammonium hydroxide (TEAOH, 25 wt.%) were mixed in a beaker with stirring at room temperature until clear, followed by slow addition of 10.76g of white carbon black (SiO 2 92 wt%) was vigorously stirred for 2 hours, 2.78g of aluminum sulfate octadecanoate was added to the continuously stirred mixture, after stirring for 1 hour, 0.2g of calcined SSZ-13 seed crystal was finally added to the mixture, which was 2% of the total mass of the silicon source, and vigorously stirred at room temperature for 1 hour, and the mixture was transferred to a stainless steel reaction vessel with a polytetrafluoroethylene liner. Crystallizing at 160 ℃ for 24 hours, taking out, quenching to room temperature, washing to neutrality by deionized water, drying at 80 ℃, and roasting in air at 550 ℃ for 6 hours to obtain the product molecular sieve powder.
FIG. 2 is an XRD pattern of the resulting product, showing that the synthesized product is a pure phase SSZ-13 molecular sieve with a relative crystallinity of 95.48% with reference to the seed crystals.
Comparative example 3
In an inorganic alkali sodium hydroxide system, under the condition of higher consumption of TMAHAOH, NH 4 The L zeolite is transformed into the CHA type SSZ-13 molecular sieve, which comprises the following steps:
27.90g of N, N, N-trimethyl-1-adamantylammonium hydroxide solution (TMAGAOH, 25 wt.%), 11.74g of deionized water and 1.38g of sodium hydroxide (NaOH, 96 wt.%) were mixed in a beaker with stirring at room temperature and stirred until clear, followed by slow addition of 9.15g of white carbon black (SiO 2 92 wt%) after vigorous stirring for 2h, NH was added to the continuously stirred mixture 4 L zeolite 1.91g (SiO 2 /Al 2 O 3 =6), after stirring for 1h, 0.2g of calcined SSZ-13 seed crystal accounting for 2% of the total mass of the silicon source was finally added, and stirring was vigorously performed at room temperature for 1h, and the above mixture was transferred to a stainless steel reaction kettle with polytetrafluoroethylene lining. Crystallizing at 160 ℃ for 24 hours, taking out, quenching to room temperature, washing to neutrality by deionized water, drying at 80 ℃, and roasting in air at 550 ℃ for 6 hours to obtain the product molecular sieve powder.
FIG. 2 is an XRD pattern of the resulting product, showing that the synthesized product was a pure phase SSZ-13 molecular sieve with a relative crystallinity of 94.62% with reference to the seed crystals.
Test examples
The molecular sieves prepared in the above examples and comparative examples were examined for their denitration catalytic properties, and the specific procedures were as follows:
the molecular sieves prepared in the examples and the comparative examples are exchanged with 1M ammonium nitrate solution at a solid-to-liquid ratio of 100 and at 80 ℃ for 3 hours, filtered, washed, dried and baked at 550 ℃ for 4 hours. Repeating the above process for 2 times, adding 0.1M copper nitrate solution into the roasted H-type SSZ-13 for solid exchange, wherein the liquid-solid ratio is 100, the exchange is carried out for 3 hours at 80 ℃, filtering, washing and drying are carried out, and the Cu-SSZ-13 is obtained.
Tabletting, crushing and sieving the prepared Cu-SSZ-13 molecular sieve catalyst, and taking 0.1g of a 40-60-mesh sample for NH 3 SCR reaction, wherein the composition of the reaction mixtureThe method comprises the following steps: 500ppm (0.05%) NO, 500ppm (0.05%) NH 3 、10％O 2 Ar gas is used as balance gas, and the volume airspeed is 80000h -1 The reaction temperature is 100-750 ℃, and the NO and NO in the tail gas are detected on line by using a Nicolet infrared gas analyzer 2 And N 2 O concentration.
Table 1 shows the molar ratios and the relative yields for all the examples and comparative examples
Table 2 shows catalyst evaluation tests, NH of examples 3-6 3 -SCR evaluation result data
The foregoing is only a specific embodiment of the invention to enable those skilled in the art to understand or practice the invention. Although described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical scheme described in the foregoing embodiments can be modified or some or all of the technical features thereof can be replaced by equivalents; such modifications and substitutions do not depart from the spirit of the embodiments, and they should be construed as covering the scope of the appended claims.
Claims (8)
1. The method for preparing the SSZ-13 molecular sieve by converting the L zeolite in the mixed alkali system is characterized by comprising the following steps of:
(1) Preparing molecular sieve crystallization starting gel: dissolving inorganic alkali in deionized water at room temperature, sequentially adding organic alkali solution and template agent N, N, N-trimethyl-1-adamantylammonium hydroxide solution, and stirring thoroughlyStirring to obtain a uniform solution; then adding a silicon source under stirring to form uniform sol; adding L zeolite, continuously stirring, adding a small amount of seed crystal, and fully stirring to obtain uniform molecular sieve crystallization starting gel; wherein the total silicon is silicon source and SiO contained in the L zeolite 2 Calculated as Al contained in L zeolite 2 O 3 The molar ratio range of the reaction materials is as follows, calculated by inorganic base as A, calculated by organic base as B and calculated by template agent as R: siO (SiO) 2 : Al 2 O 3 : A: B: R: H 2 O＝1: (0.00167~0.0333): (0.05~0.3): (0.05~0.4): (0.03~0.1): (10~20)；
(2) And (3) hydrothermal crystallization: transferring the molecular sieve crystallization starting gel prepared in the first step into a hydrothermal high-pressure reaction kettle, crystallizing at 150-180 ℃ for 4-48 h, centrifuging after crystallization, washing with deionized water to be neutral, and drying to obtain molecular sieve raw powder;
(3) High-temperature roasting: roasting the molecular sieve raw powder obtained in the step (2) in air at 550-600 ℃ for 6-10 hours to obtain a final product SSZ-13 molecular sieve crystallization product.
2. The method for preparing the SSZ-13 molecular sieve by converting L zeolite in a mixed alkali system according to claim 1, wherein the inorganic alkali is sodium hydroxide or potassium hydroxide.
3. The method for preparing the SSZ-13 molecular sieve by converting L zeolite in a mixed alkali system according to claim 1, wherein the organic alkali is tetramethyl ammonium hydroxide, tetraethyl ammonium hydroxide or tetrapropyl ammonium hydroxide.
4. The method for preparing the SSZ-13 molecular sieve by transferring the L zeolite in the mixed alkali system according to claim 1, wherein the silicon source is white carbon black, solid silica gel, silica sol, water glass or tetraethoxysilane.
5. The method for preparing SSZ-13 molecular sieve by transferring L zeolite in mixed alkali system according to claim 1The method is characterized in that the L zeolite is NaK type L zeolite, NH 4 Form L zeolite or H form L zeolite.
6. The method for preparing the SSZ-13 molecular sieve by transferring the L zeolite in the mixed alkali system according to claim 1, wherein the seed crystal is 0.3-3% of the total mass of the silicon source.
7. The method for preparing the SSZ-13 molecular sieve by transferring the L zeolite in the mixed alkali system according to claim 1, wherein the seed crystal is the SSZ-13 molecular sieve or the SAPO-34 molecular sieve with chabazite crystal phase.
8. The method for preparing the SSZ-13 molecular sieve by converting L zeolite in a mixed alkali system according to claim 1, wherein the crystal grain size of the crystallized product of the SSZ-13 molecular sieve is 100-500nm.
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