CN117923509A - Method for utilizing FAU molecular sieve crystallization mother liquor - Google Patents
Method for utilizing FAU molecular sieve crystallization mother liquor Download PDFInfo
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- CN117923509A CN117923509A CN202211327755.3A CN202211327755A CN117923509A CN 117923509 A CN117923509 A CN 117923509A CN 202211327755 A CN202211327755 A CN 202211327755A CN 117923509 A CN117923509 A CN 117923509A
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- 239000002808 molecular sieve Substances 0.000 title claims abstract description 169
- 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 169
- 239000012452 mother liquor Substances 0.000 title claims abstract description 80
- 238000002425 crystallisation Methods 0.000 title claims abstract description 46
- 230000008025 crystallization Effects 0.000 title claims abstract description 46
- 238000000034 method Methods 0.000 title claims abstract description 35
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 80
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 63
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 62
- 239000000203 mixture Substances 0.000 claims abstract description 52
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 41
- 239000000377 silicon dioxide Substances 0.000 claims abstract description 38
- 229910004298 SiO 2 Inorganic materials 0.000 claims abstract description 37
- 229910052681 coesite Inorganic materials 0.000 claims abstract description 36
- 229910052906 cristobalite Inorganic materials 0.000 claims abstract description 36
- 229910052682 stishovite Inorganic materials 0.000 claims abstract description 36
- 229910052905 tridymite Inorganic materials 0.000 claims abstract description 36
- 230000015572 biosynthetic process Effects 0.000 claims abstract description 34
- 238000003786 synthesis reaction Methods 0.000 claims abstract description 34
- 238000001914 filtration Methods 0.000 claims abstract description 31
- 229910001868 water Inorganic materials 0.000 claims abstract description 27
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 23
- 229910052593 corundum Inorganic materials 0.000 claims abstract description 23
- 229910001845 yogo sapphire Inorganic materials 0.000 claims abstract description 23
- 238000005216 hydrothermal crystallization Methods 0.000 claims abstract description 22
- 230000032683 aging Effects 0.000 claims abstract description 21
- 239000000463 material Substances 0.000 claims abstract description 16
- 238000002156 mixing Methods 0.000 claims abstract description 16
- KKCBUQHMOMHUOY-UHFFFAOYSA-N Na2O Inorganic materials [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 claims abstract description 15
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 15
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 15
- 239000010703 silicon Substances 0.000 claims abstract description 15
- 239000003513 alkali Substances 0.000 claims abstract description 13
- 150000001875 compounds Chemical class 0.000 claims abstract description 8
- 238000004064 recycling Methods 0.000 claims abstract description 7
- 238000003756 stirring Methods 0.000 claims abstract description 6
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical group [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 24
- 239000011734 sodium Substances 0.000 claims description 19
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 15
- 235000019353 potassium silicate Nutrition 0.000 claims description 13
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 6
- WNROFYMDJYEPJX-UHFFFAOYSA-K aluminium hydroxide Chemical compound [OH-].[OH-].[OH-].[Al+3] WNROFYMDJYEPJX-UHFFFAOYSA-K 0.000 claims description 6
- VSCWAEJMTAWNJL-UHFFFAOYSA-K aluminium trichloride Chemical compound Cl[Al](Cl)Cl VSCWAEJMTAWNJL-UHFFFAOYSA-K 0.000 claims description 4
- DIZPMCHEQGEION-UHFFFAOYSA-H aluminium sulfate (anhydrous) Chemical compound [Al+3].[Al+3].[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O.[O-]S([O-])(=O)=O DIZPMCHEQGEION-UHFFFAOYSA-H 0.000 claims description 3
- BNGXYYYYKUGPPF-UHFFFAOYSA-M (3-methylphenyl)methyl-triphenylphosphanium;chloride Chemical compound [Cl-].CC1=CC=CC(C[P+](C=2C=CC=CC=2)(C=2C=CC=CC=2)C=2C=CC=CC=2)=C1 BNGXYYYYKUGPPF-UHFFFAOYSA-M 0.000 claims description 2
- 239000004115 Sodium Silicate Substances 0.000 claims description 2
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 claims description 2
- VXAUWWUXCIMFIM-UHFFFAOYSA-M aluminum;oxygen(2-);hydroxide Chemical compound [OH-].[O-2].[Al+3] VXAUWWUXCIMFIM-UHFFFAOYSA-M 0.000 claims description 2
- ANBBXQWFNXMHLD-UHFFFAOYSA-N aluminum;sodium;oxygen(2-) Chemical compound [O-2].[O-2].[Na+].[Al+3] ANBBXQWFNXMHLD-UHFFFAOYSA-N 0.000 claims description 2
- 239000006229 carbon black Substances 0.000 claims description 2
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 2
- 239000000741 silica gel Substances 0.000 claims description 2
- 229910002027 silica gel Inorganic materials 0.000 claims description 2
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 claims description 2
- 229910001388 sodium aluminate Inorganic materials 0.000 claims description 2
- 229910052911 sodium silicate Inorganic materials 0.000 claims description 2
- 150000007529 inorganic bases Chemical class 0.000 claims 1
- 239000008367 deionised water Substances 0.000 abstract description 16
- 229910021641 deionized water Inorganic materials 0.000 abstract description 16
- 239000002351 wastewater Substances 0.000 abstract description 10
- 238000004519 manufacturing process Methods 0.000 abstract description 8
- 239000000047 product Substances 0.000 description 33
- 238000006243 chemical reaction Methods 0.000 description 20
- 238000001228 spectrum Methods 0.000 description 16
- 239000012065 filter cake Substances 0.000 description 14
- 238000002360 preparation method Methods 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 6
- 239000013078 crystal Substances 0.000 description 6
- 239000012535 impurity Substances 0.000 description 6
- 238000004821 distillation Methods 0.000 description 5
- 238000005406 washing Methods 0.000 description 5
- 238000001035 drying Methods 0.000 description 4
- 239000012071 phase Substances 0.000 description 4
- 229910052708 sodium Inorganic materials 0.000 description 4
- 230000002194 synthesizing effect Effects 0.000 description 4
- 150000001412 amines Chemical class 0.000 description 3
- 239000000499 gel Substances 0.000 description 2
- 238000005342 ion exchange Methods 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 235000012239 silicon dioxide Nutrition 0.000 description 2
- 239000002910 solid waste Substances 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 1
- PXGOKWXKJXAPGV-UHFFFAOYSA-N Fluorine Chemical compound FF PXGOKWXKJXAPGV-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 235000011941 Tilia x europaea Nutrition 0.000 description 1
- 238000002479 acid--base titration Methods 0.000 description 1
- CSDREXVUYHZDNP-UHFFFAOYSA-N alumanylidynesilicon Chemical compound [Al].[Si] CSDREXVUYHZDNP-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 239000006227 byproduct Substances 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- 239000000701 coagulant Substances 0.000 description 1
- 238000004939 coking Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000000839 emulsion Substances 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 239000000706 filtrate Substances 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 238000001027 hydrothermal synthesis Methods 0.000 description 1
- 239000004571 lime Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 239000002893 slag Substances 0.000 description 1
- 239000010802 sludge Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000006228 supernatant Substances 0.000 description 1
- 238000004065 wastewater treatment Methods 0.000 description 1
Classifications
-
- 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
- C01B39/14—Type A
-
- 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
-
- 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
- C01B39/14—Type A
- C01B39/16—Type A from aqueous solutions of an alkali metal aluminate and an alkali metal silicate excluding any other source of alumina or silica but seeds
-
- 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
Landscapes
- 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 method for utilizing FAU molecular sieve crystallization mother liquor is characterized by comprising the following steps: uniformly mixing FAU molecular sieve mother liquor, a silicon source, inorganic alkali, water and an aluminum source to obtain an A-type molecular sieve synthesis system mixture with a material molar ratio of SiO2/Al2O3＝1.85-1.99、Na2O/SiO2＝1.0-1.6、H2O/SiO2＝45-65, carrying out aging and hydrothermal crystallization on the mixture, and recovering products to obtain an A-type molecular sieve and a filtration mother liquor of the A-type molecular sieve; or further mixing the filtration mother liquor of the A-type molecular sieve and the aluminum-containing compound uniformly, and stirring for 2-8 hours at 160-200 ℃ to obtain a recycling aluminum source with the SiO 2 content of 50-300 ppm; uniformly mixing a silicon source, inorganic alkali, a recycled aluminum source and water to obtain a FAU molecular sieve synthesis system mixture, carrying out aging and hydrothermal crystallization on the mixture, and recovering products to obtain the FAU molecular sieve and FAU molecular sieve crystallization mother liquor. The method not only can completely recycle FAU molecular sieve mother liquor, avoid the discharge of mother liquor wastewater, reduce the consumption of inorganic alkali and deionized water and obviously reduce the production cost, but also can be flexibly used for preparing FAU molecular sieves and/or A-type molecular sieves.
Description
Technical Field
The invention relates to a method for utilizing a molecular sieve crystallization mother liquor, in particular to a method for recycling FAU molecular sieve crystallization mother liquor.
Background
The FAU molecular sieve has larger micropore diameter, so that the FAU molecular sieve has higher adsorption capacity and lower framework silicon-aluminum ratio, and also has good adsorption and ion exchange performance, therefore, the FAU molecular sieve is widely used in the fields of separation, catalysis, ion exchange and the like. At present, the FAU molecular sieve is produced by a liquid phase hydrothermal synthesis method basically in industry, however, the content of inorganic alkali and silicon in a large amount of molecular sieve crystallization mother liquor produced by the production method is high, and the environmental protection treatment difficulty is high.
CN106430228a discloses a method for treating molecular sieve crystallization mother liquor, which is characterized in that molecular sieve crystallization mother liquor is sucked into a reduced pressure distillation still, steam is introduced into a jacket of the distillation still to heat the distillation still, organic amine and water in the crystallization mother liquor are evaporated, the organic amine and water enter a condenser, condensate enters a solvent storage tank, a stirring device is arranged in the distillation still to continuously turn evaporation materials, coking on the cavity wall is prevented, and slag is automatically discharged after the water content of residues in the distillation still reaches the standard. The method can fully recycle the organic amine and water in the crystallization mother liquor, and realizes no wastewater discharge.
CN105000642B discloses a method for treating siliceous waste water produced in the process of preparing molecular sieve, which comprises the steps of collecting and preparing filtrate, mother liquor and washing liquor produced in the process of preparing molecular sieve to form gel waste water, adding lime emulsion with concentration of 8-10%, stirring for a period of time, standing, wherein the content of soluble silicon in each liter of gel waste water is 500-1000mg, recycling supernatant, and discharging bottom sludge.
CN104556460B discloses a method for removing fluorine and phosphorus from waste water produced by PSRY molecular sieve production, which comprises mixing the waste water produced by PSRY molecular sieve production with solid waste residue produced in other molecular sieve production waste water treatment processes, dissolving aluminum in the solid waste residue into the waste water in the form of Al 3+, adjusting the pH value of the mixed system to above 6, reacting Al 3+ with F -、PO4 3- to form precipitate, adding coagulant aid (PAM) to react, and then carrying out solid-liquid separation.
Disclosure of Invention
The invention aims to provide a method for utilizing FAU molecular sieve crystallization mother liquor, which is different from the prior art, and the method not only can fully recycle FAU molecular sieve mother liquor, avoid the discharge of mother liquor wastewater, reduce the consumption of inorganic alkali and deionized water, obviously reduce the production cost, but also can be flexibly used for preparing FAU molecular sieves and/or A-type molecular sieves.
Therefore, the method for utilizing FAU molecular sieve crystallization mother liquor provided by the invention is characterized by comprising the following steps: uniformly mixing FAU molecular sieve mother liquor, a silicon source, inorganic alkali, water and an aluminum source to obtain an A-type molecular sieve synthesis system mixture with a material molar ratio of SiO2/Al2O3＝1.85-1.99、Na2O/SiO2＝1.0-1.6、H2O/SiO2＝45-65, carrying out aging and hydrothermal crystallization on the mixture, and recovering products to obtain an A-type molecular sieve and a filtration mother liquor of the A-type molecular sieve; or further mixing the filtration mother liquor of the A-type molecular sieve and the aluminum-containing compound uniformly, and stirring for 2-8 hours at 160-200 ℃ to obtain a recycling aluminum source with the SiO 2 content of 50-300 ppm; uniformly mixing a silicon source, inorganic alkali, a recycled aluminum source and water to obtain a FAU molecular sieve synthesis system mixture, carrying out aging and hydrothermal crystallization on the mixture, and recovering products to obtain the FAU molecular sieve and FAU molecular sieve mother liquor.
According to the utilization method of the FAU molecular sieve crystallization mother liquor, the FAU molecular sieve crystallization mother liquor with higher silicon dioxide content is firstly used for synthesizing the A-type molecular sieve, and the silicon dioxide content in the obtained A-type molecular sieve crystallization mother liquor is obviously reduced, so that the A-type molecular sieve crystallization mother liquor is used for preparing a recycled aluminum source, the obtained recycled aluminum source can be used for synthesizing the FAU molecular sieve and the A-type molecular sieve without any post-treatment, thereby realizing the complete recycling of the FAU molecular sieve crystallization mother liquor, avoiding the emission of crystallization mother liquor wastewater, enabling the production to be more environment-friendly, reducing the use of inorganic alkali and deionized water, being beneficial to reducing the production cost and further being capable of producing the A-type molecular sieve as a byproduct.
Drawings
Figure 1 is an XRD spectrum of a type A molecular sieve prepared in example 1 of the present invention.
Fig. 2 is an XRD spectrum of the FAU molecular sieve prepared in example 1 of the present invention.
Figure 3 is an XRD spectrum of a type A molecular sieve prepared in example 2 of the present invention.
Fig. 4 is an XRD spectrum of the FAU molecular sieve prepared in example 3 of the present invention.
Fig. 5 is an XRD spectrum of the product obtained in comparative example 1.
FIG. 6 is an XRD spectrum of the product obtained in comparative example 2.
Detailed Description
The FAU molecular sieve crystallization mother liquor mainly contains Na, si, al and other components, different components are difficult to separate by adopting a conventional method, and the FAU molecular sieve crystallization mother liquor is directly recycled in a synthesis system, or the FAU molecular sieve crystallization mother liquor is firstly prepared into an aluminum source and then synthesized into the FAU molecular sieve by using the obtained aluminum source, so that impurity crystals are easy to form.
The inventor finds that the FAU molecular sieve crystallization mother liquor with higher silicon content is firstly used for synthesizing the A-type molecular sieve to obtain the crystallization mother liquor of the A-type molecular sieve with lower silicon content, and then the obtained crystallization mother liquor of the A-type molecular sieve is used for preparing a recycled aluminum source, and the obtained recycled aluminum source can be directly used for synthesizing the FAU molecular sieve without any treatment.
The invention provides a method for utilizing FAU molecular sieve crystallization mother liquor, which is characterized by comprising the following steps: uniformly mixing FAU molecular sieve crystallization mother liquor, a silicon source, inorganic alkali, water and an aluminum source to obtain an A type molecular sieve synthesis system mixture with a material molar ratio of SiO2/Al2O3＝1.85-1.99、Na2O/SiO2＝1.0-1.6、H2O/SiO2＝45-65, carrying out aging and hydrothermal crystallization on the mixture, and recovering products to obtain an A type molecular sieve and a filtration mother liquor of the A type molecular sieve; or further mixing the filtration mother liquor of the A-type molecular sieve and the aluminum-containing compound uniformly, and stirring for 2-8 hours at 160-200 ℃ to obtain a recycling aluminum source with the SiO 2 content of 50-300 ppm; uniformly mixing a silicon source, inorganic alkali, a recycled aluminum source and water to obtain a FAU molecular sieve synthesis system mixture, carrying out aging and hydrothermal crystallization on the mixture, and recovering products to obtain the FAU molecular sieve and FAU molecular sieve crystallization mother liquor.
In the invention, the A-type molecular sieve synthesis system mixture is aged and hydrothermally crystallized, wherein the aging temperature is 20-35 ℃, the aging time is 3-12 hours, the hydrothermally crystallized temperature is 90-130 ℃, and the hydrothermally crystallized time is 6-16 hours. In the A-type molecular sieve filtration mother liquor, the content of SiO 2 is 100-900ppm, and the content of Al 2O3 is 500-2000ppm.
In the FAU molecular sieve synthesis system mixture, the material molar ratio is SiO2/Al2O3＝2.6-10.0,Na2O/SiO2＝0.25-1.5,H2O/SiO2＝20-70., the FAU molecular sieve synthesis system mixture is aged and subjected to hydrothermal crystallization, the aging temperature is 25-40 ℃, the aging time is 12-24 hours, the hydrothermal crystallization temperature is 95-120 ℃, and the hydrothermal crystallization time is 2-48 hours.
In the invention, the aluminum source can be replaced by the recycled aluminum source, and NaOH and deionized water are preferably added in the mixing of the filtration mother liquor of the A-type molecular sieve and the aluminum-containing compound in the preparation process of the recycled aluminum source. The molar ratio of Na 2O/Al2O3 of the recycled aluminum source is 1.6-2.8, the content of Al 2O3 is 16.0-22.0 mass percent, and the content of SiO 2 is 50-300ppm.
In the invention, the content of Al 2O3 in the recycled aluminum source is calculated by the addition amount of an aluminum-containing compound in the preparation process, the content of SiO 2 is calculated by the addition amount of an A-type molecular sieve filtration mother liquor in the preparation process and the content of SiO 2, and the content of Na 2 O is measured by an acid-base titration method.
In the present invention, the aluminum-containing compound is at least one selected from the group consisting of metallic aluminum, aluminum oxide, aluminum hydroxide, pseudo-boehmite, aluminum sulfate, aluminum chloride, aluminum nitrate and sodium aluminate.
In the invention, the silicon source is at least one selected from tetraethoxysilane, silica sol, water glass, sodium silicate, silica gel and white carbon black. When the silicon source is water glass, the mass fraction of Na 2 O is 6.0-12.0%, and the mass fraction of SiO 2 is 25-35%. The inorganic alkali is sodium hydroxide or potassium hydroxide. The content of SiO 2 in the FAU molecular sieve crystallization mother liquor is 3000-80000mg/L.
As is well known to those skilled in the art, in the XRD spectrum of the molecular sieve, the stronger diffraction peaks near 2θ=6.1 °, 10.0 °, 11.7 °, and 15.4 ° are the characteristic diffraction peaks of the FAU molecular sieve, and no other diffraction peaks are in the range of 2θ=6.1 ° to 15.4 °, which indicates that the sample has no impurity crystals and is a pure phase FAU molecular sieve.
The present invention will be described in detail by way of examples, but the present invention is not limited thereto.
Example 1
This example illustrates the use of FAU molecular sieve crystallization mother liquor in the preparation of a type a molecular sieve and FAU molecular sieve.
(1) Preparation of aluminum source
100Kg of aluminum hydroxide, 90.91kg of sodium hydroxide and 210kg of deionized water were added to the reaction vessel, heated to 100℃and stirred for 1 hour to obtain an aluminum source in which the Al 2O3 content was 18.52 mass%, the Na 2 O content was 20.26 mass% and the Na 2O/Al2O3 molar ratio was 1.80.
(2) Synthetic A-type molecular sieve
61.36Kg of FAU molecular sieve mother liquor (SiO 2 content is 9755 mg/L), 46.35kg of deionized water, 43.92kg of aluminum source prepared in the step (1) and 29.12kg of water glass (SiO 2 content is 29.17 mass percent, na 2 O content is 8.12 mass percent, and the same applies below) are added into a reaction kettle to be uniformly mixed to obtain an A-type molecular sieve synthesis system mixture, the molar ratio of each material in the mixture is SiO 2/Al2O3＝1.90,Na2O/SiO2＝1.44,H2O/SiO2 =55, the mixture is subjected to standing aging at 30 ℃ for 8 hours, hydrothermal crystallization at 100 ℃ for 12 hours, and filtration to obtain a molecular sieve filter cake and a filtration mother liquor.
The filter cake is washed and dried at 120 ℃ to obtain a product, the XRD spectrum of the product is shown in figure 1, and stronger diffraction peaks appear near 2θ=7.2 °, 10.1 °, 12.4 °, 16.1 ° and the like, which indicates that the obtained product is an A-type molecular sieve. The composition of the filtration mother liquor of the A-type molecular sieve was 4.03 mass% of Na 2 O, 587ppm of SiO 2 and 1366ppm of Al 2O3.
(3) Preparation of recycled aluminum source
100Kg of aluminum hydroxide, 90.91kg of sodium hydroxide, 60kg of deionized water and 120kg of the filtration mother liquor of the type A molecular sieve obtained in the step (2) are added into a reaction kettle, the reaction kettle is sealed, the reaction kettle is heated to 170 ℃ and stirred for 5 hours, and a recycled aluminum source is obtained, wherein the recycled aluminum source contains 17.41 mass percent of Al 2O3, 20.30 mass percent of Na 2 O, 189.91ppm of SiO 2 and 1.92 of Na 2O/Al2O3.
(4) Synthesis of FAU molecular sieves
Adding 59.13kg of deionized water, 13.92kg of the recycled aluminum source prepared in the step (3) and 14.66kg of water glass into a reaction kettle, and uniformly mixing to obtain a FAU molecular sieve synthesis system mixture, wherein the molar ratio of each material in the mixture is SiO 2/Al2O3＝3.00,Na2O/SiO2＝0.91,H2O/SiO2 = 60; the mixture is subjected to standing aging for 24 hours at 30 ℃, hydrothermal crystallization for 8 hours at 100 ℃ and filtration to obtain a molecular sieve filter cake and molecular sieve crystallization mother liquor.
The molecular sieve filter cake is washed and dried at 80 ℃ to obtain a product, an XRD spectrum of the product is shown in figure 2, stronger diffraction peaks appear near 2θ=6.1 °, 10.0 °, 11.7 °, 15.4 ° and the like, and no diffraction peaks exist near 2θ=7.2 °, 10.1 °, 12.4 °, 16.1 ° and the like, so that the product is free of A-type molecular sieve impurity crystals and is a pure-phase FAU molecular sieve. The content of SiO 2 in the FAU molecular sieve crystallization mother liquor is 8908mg/L.
Example 2
This example illustrates the use of the recycled aluminum source prepared in example 1 (3) in place of the aluminum source for the synthesis of a type a molecular sieve:
53.68kg of FAU molecular sieve crystallization mother liquor (SiO 2 content is 8908 mg/L), 43.38kg of deionized water, 54.98kg of the recycled aluminum source (Al 2O3 content is 17.41 mass percent, na 2 O content is 20.30 mass percent, siO 2 content is 189.91ppm, na 2O/Al2O3 molar ratio is 1.92) and 34.07kg of water glass prepared in the example 1 (3) are added into a reaction kettle and mixed uniformly to obtain an A-type molecular sieve synthesis system mixture, the molar ratio of each material in the mixture is SiO 2/Al2O3＝1.85,Na2O/SiO2＝1.50,H2O/SiO2 =48, and the mixture is subjected to standing aging at 33 ℃ for 10 hours, hydrothermal crystallization at 105 ℃ for 8 hours and filtration to obtain a molecular sieve filter cake and a filtration mother liquor thereof.
The filter cake is washed and dried at 120 ℃ to obtain a product, the XRD spectrum of the product is shown in figure 3, and stronger diffraction peaks appear near 2θ=7.2 °, 10.1 °, 12.4 °, 16.1 ° and the like, and the product is shown as a type A molecular sieve.
The A-type molecular sieve filtration mother liquor has the composition of 5.39 mass percent of Na 2 O, 629ppm of SiO 2 and 1506ppm of Al 2O3.
Example 3
This example illustrates the use of FAU molecular sieve crystallization mother liquor in the preparation of FAU molecular sieves.
(1) Preparation of recycled aluminum source
100Kg of aluminum hydroxide, 101.01kg of sodium hydroxide, 40kg of deionized water and 160kg of the molecular sieve A filtering mother liquor obtained in example 2 were added into a reaction kettle, the reaction kettle was sealed, heated to 180 ℃ and stirred for 4 hours, and a recycled aluminum source was obtained, wherein the content of Al 2O3 was 16.11 mass%, the content of Na 2 O was 21.67 mass%, the content of SiO 2 was 250.97ppm and the molar ratio of Na 2O/Al2O3 was 2.21.
(2) Synthesis of FAU molecular sieves
Adding 54.26kg of deionized water, 18.84kg of the recycled aluminum source prepared in the step (1) and 17.60kg of water glass into a reaction kettle, and uniformly mixing to obtain a FAU molecular sieve synthesis system mixture, wherein the molar ratio of each material in the mixture is SiO 2/Al2O3＝2.88,Na2O/SiO2＝1.04,H2O/SiO2 =50; the mixture is subjected to standing aging for 20 hours at 30 ℃, hydrothermal crystallization for 24 hours at 95 ℃ and filtration to obtain a molecular sieve filter cake and molecular sieve crystallization mother liquor.
The molecular sieve filter cake is washed and dried at 80 ℃ to obtain a product, the XRD spectrum of the product is shown in figure 4, stronger diffraction peaks appear near 2θ=6.1 °, 10.0 °, 11.7 °, 15.4 ° and the like, and no diffraction peaks exist near 2θ=7.2 °, 10.1 °, 12.4 °, 16.1 ° and the like, which indicates that the product has no A-type molecular sieve impurity crystal and is a pure phase FAU molecular sieve.
The content of SiO 2 in the FAU molecular sieve crystallization mother liquor is 8467mg/L.
Example 4
This example illustrates the synthesis of a type a molecular sieve using the recycled aluminum source prepared in step (1) of example 3 and the FAU molecular sieve crystallization mother liquor obtained in step (2).
53.26Kg of FAU molecular sieve mother liquor (the SiO 2 content is 8467 mg/L), 54.00kg of deionized water, 45.10kg of the recycled aluminum source prepared in the step 1 (3) and 27.02kg of water glass are added into a reaction kettle to be uniformly mixed to obtain an A molecular sieve synthesis system mixture, the molar ratio of each material in the mixture is SiO 2/Al2O3＝1.95,Na2O/SiO2＝1.60,H2O/SiO2 =60, standing and ageing are carried out at 33 ℃ for 8 hours, hydrothermal crystallization is carried out at 95 ℃ for 15 hours, and a molecular sieve filter cake and a molecular sieve filtration mother liquor are obtained by filtration.
Washing a molecular sieve filter cake, and drying at 120 ℃ to obtain a product, wherein an XRD spectrum of the product has the same characteristics as those of figure 3, which shows that the obtained product is an A-type molecular sieve; the composition of the A-type molecular sieve filtration mother liquor is 5.72 mass percent of Na 2 O, 704 ppm of SiO 2 and 1583ppm of Al 2O3.
Example 5
This example illustrates the synthesis of a type a molecular sieve using the recycled aluminum source prepared in step (3) of example 1.
120.31Kg of FAU molecular sieve mother liquor (SiO 2 content is 32700 mg/L), 0.84kg of sodium hydroxide, 42.98kg of the recycled aluminum source prepared in the step 1 (3) and 14.16kg of water glass are added into a reaction kettle to be uniformly mixed, the molar ratio of each material is SiO 2/Al2O3＝1.98,Na2O/SiO2＝1.60,H2O/SiO2 =62, and the mixture is subjected to standing aging at 35 ℃ for 6 hours, hydrothermal crystallization at 98 ℃ for 12 hours, and then a molecular sieve filter cake and a molecular sieve filtration mother liquor are obtained by filtration.
Washing a molecular sieve filter cake, and drying at 120 ℃ to obtain a product, wherein an XRD spectrum of the product has the same characteristics as those of figure 3, and the obtained product is an A-type molecular sieve; the A-type molecular sieve filtration mother liquor has a Na 2 O content of 5.43 mass%, a SiO 2 content of 722ppm and an Al 2O3 content of 1429ppm.
Example 6
This example illustrates the synthesis of FAU molecular sieves using the recycled aluminum source prepared in step (1) of example 3.
43.12Kg of deionized water, 7.97kg of the recycled aluminum source prepared in the step (1), 8.84kg of aluminum sulfate solution (Al 2O3 content) and 35.20kg of water glass are added into a reaction kettle and uniformly mixed to obtain a FAU molecular sieve synthesis system mixture, wherein the molar ratio of each material in the mixture is SiO 2/Al2O3＝8.80,Na2O/SiO2＝0.32,H2O/SiO2 =25. Transferring the mixture into a closed reaction kettle, standing and ageing for 24 hours at 30 ℃, carrying out hydrothermal crystallization for 48 hours at 95 ℃, and filtering to obtain a molecular sieve filter cake and molecular sieve crystallization mother liquor.
The molecular sieve filter cake is washed and dried at 80 ℃ to obtain a product, and an XRD spectrum of the product has the same characteristics as that of figure 2, which shows that the obtained product is a pure-phase FAU molecular sieve. The SiO 2 content in the FAU molecular sieve crystallization mother liquor is 40300mg/L.
Comparative example 1
This comparative example illustrates the use of the FAU molecular sieve crystallization mother liquor obtained in step 1 (4) and the aluminum source obtained in step 1 (1) for direct synthesis of FAU molecular sieves.
37.91Kg of FAU molecular sieve crystallization mother liquor obtained in the step 1 (4), 73.71kg of deionized water, 31.87kg of aluminum source obtained in the step 1 (1) and 33.13kg of water glass are added into a reaction kettle and uniformly mixed to obtain a molecular sieve synthesis system mixture, wherein the molar ratio of each material in the mixture is SiO 2/Al2O3＝2.88,Na2O/SiO2＝1.04,H2O/SiO2 =50. Transferring the mixture into a closed reaction kettle, standing and ageing for 20 hours at 30 ℃ and carrying out hydrothermal crystallization for 24 hours at 95 ℃, filtering, washing and drying the obtained crystallized product, wherein an XRD spectrum is shown in figure 5, and as can be seen from figure 5, stronger diffraction peaks appear near 2θ=6.1°, 10.0 °, 11.7 °, 15.4 ° and the like, and the product is mainly FAU molecular sieve, but weaker diffraction peaks appear near 2θ=7.2 °, 10.1 °, 12.4 °, 16.1 ° and the like, so that a small amount of A-type molecular sieve impurity crystals exist in the product.
Comparative example 2
This comparative example illustrates the preparation of a recycled aluminum source for direct synthesis of FAU molecular sieves using the FAU molecular sieve crystallization mother liquor obtained in step (4) of example 1.
(1) Preparation of recycled aluminum source
100Kg of aluminum hydroxide, 90.91kg of sodium hydroxide, 60kg of deionized water and 120kg of FAU molecular sieve crystallization mother liquor obtained in the step (4) of example 1 are added into a reaction kettle, the reaction kettle is sealed, and the mixture is heated to 120 ℃ and stirred for 5 hours, so that a recycled aluminum source is obtained, wherein the content of Al 2O3 is 17.36 mass percent, the content of Na 2 O is 20.34 mass percent, the content of SiO 2 is 2881.99ppm and the molar ratio of Na 2O/Al2O3 is 1.93.
(2) Synthesis of FAU molecular sieves
107.01Kg of deionized water, 1.35kg of kgNaOH and 34.00kg of the recycled aluminum source prepared in the step (1) and 34.28kg of water glass are added into a reaction kettle and uniformly mixed to obtain a molecular sieve synthesis system mixture, wherein the molar ratio of each material in the mixture is SiO 2/Al2O3＝2.88,Na2O/SiO2＝1.04,H2O/SiO2 =50. Transferring the mixture into a closed reaction kettle, standing and ageing for 24 hours at 30 ℃ and carrying out hydrothermal crystallization for 24 hours at 95 ℃, filtering, washing and drying the obtained crystallized product at 80 ℃, wherein an XRD spectrum is shown in figure 6, and as can be seen from figure 6, stronger diffraction peaks appear near 2θ=6.1°, 10.0 °, 11.7 °, 15.4 ° and the like, and the product is mainly a FAU molecular sieve, but weaker diffraction peaks appear near 2θ=7.2 °, 10.1 °, 12.4 °, 16.1 ° and the like, so that a small amount of A-type molecular sieve impurity crystals exist in the product.
Claims (15)
1. The method for utilizing FAU molecular sieve crystallization mother liquor is characterized by comprising the following steps: uniformly mixing FAU molecular sieve mother liquor, a silicon source, inorganic alkali, water and an aluminum source to obtain an A-type molecular sieve synthesis system mixture with a material molar ratio of SiO2/Al2O3＝1.85-1.99、Na2O/SiO2＝1.0-1.6、H2O/SiO2＝45-65, carrying out aging and hydrothermal crystallization on the mixture, and recovering products to obtain an A-type molecular sieve and a filtration mother liquor of the A-type molecular sieve; or further mixing the filtration mother liquor of the A-type molecular sieve and the aluminum-containing compound uniformly, and stirring for 2-8 hours at 160-200 ℃ to obtain a recycling aluminum source with the SiO 2 content of 50-300 ppm; uniformly mixing a silicon source, inorganic alkali, a recycled aluminum source and water to obtain a FAU molecular sieve synthesis system mixture, carrying out aging and hydrothermal crystallization on the mixture, and recovering products to obtain the FAU molecular sieve and FAU molecular sieve crystallization mother liquor.
2. The method according to claim 1, wherein the aluminum source has a Na 2O/Al2O3 molar ratio of 1.6 to 2.8 and an al 2O3 content of 16.5 to 22.0 mass%.
3. The process of claim 1 wherein the type a molecular sieve synthesis system mixture is aged at a temperature of from 20 to 35 ℃ for a period of from 3 to 12 hours.
4. The method according to claim 1, wherein the mixture of the a-type molecular sieve synthesis system is subjected to hydrothermal crystallization at a temperature of 90-130 ℃ for 6-16 hours.
5. The method according to claim 1, wherein the SiO 2 content is 100-900ppm and the Al 2O3 content is 500-2000ppm in the filtration mother liquor of the type A molecular sieve.
6. The method of claim 1 wherein said aluminum source is replaced with said recycled aluminum source.
7. The method according to claim 1 or 6, wherein the recycled aluminum source has a Na 2O/Al2O3 molar ratio of 1.6 to 2.8 and an Al 2O3 content of 16.0 to 22.0 mass%.
8. The method of claim 1, wherein the aluminum-containing compound is selected from at least one of metallic aluminum, aluminum oxide, aluminum hydroxide, pseudo-boehmite, aluminum sulfate, aluminum chloride, aluminum nitrate, and sodium aluminate.
9. The method of claim 1, wherein the FAU molecular sieve synthesis system mixture comprises the following materials in a molar ratio of SiO2/Al2O3＝2.6-10.0、Na2O/SiO2＝0.25-1.5、H2O/SiO2＝20-70.
10. The method of claim 1, wherein the FAU-type molecular sieve synthesis system mixture is aged at a temperature of 25 to 40 ℃ for a period of 12 to 24 hours.
11. The method according to claim 1, wherein the FAU-type molecular sieve synthesis system mixture is subjected to hydrothermal crystallization at a temperature of 95-120 ℃ for 2-48 hours.
12. The method of claim 1, wherein the silicon source is selected from at least one of ethyl orthosilicate, silica sol, water glass, sodium silicate, silica gel, and white carbon black.
13. The method of claim 12, wherein the water glass has a Na 2 O mass fraction of 6.0% to 10.0% and a SiO 2 mass fraction of 20% to 30%.
14. The method of claim 1, wherein the inorganic base is sodium hydroxide or potassium hydroxide.
15. The method of claim 1, wherein the FAU molecular sieve crystallization mother liquor has a SiO 2 content of 3000-80000mg/L.
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