CN115417421A - Loess-based 4A type molecular sieve and preparation method and application thereof - Google Patents
Loess-based 4A type molecular sieve and preparation method and application thereof Download PDFInfo
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- CN115417421A CN115417421A CN202210977703.4A CN202210977703A CN115417421A CN 115417421 A CN115417421 A CN 115417421A CN 202210977703 A CN202210977703 A CN 202210977703A CN 115417421 A CN115417421 A CN 115417421A
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- loess
- molecular sieve
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- 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 121
- 239000002808 molecular sieve Substances 0.000 title claims abstract description 120
- 238000002360 preparation method Methods 0.000 title claims abstract description 18
- 239000011734 sodium Substances 0.000 claims abstract description 77
- 229910052708 sodium Inorganic materials 0.000 claims abstract description 76
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 claims abstract description 75
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims abstract description 65
- 238000000034 method Methods 0.000 claims abstract description 56
- 239000002994 raw material Substances 0.000 claims abstract description 46
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 44
- 238000005406 washing Methods 0.000 claims abstract description 38
- 238000006243 chemical reaction Methods 0.000 claims abstract description 37
- 239000000243 solution Substances 0.000 claims abstract description 35
- 239000003513 alkali Substances 0.000 claims abstract description 33
- 239000013078 crystal Substances 0.000 claims abstract description 30
- 239000002002 slurry Substances 0.000 claims abstract description 30
- 238000002425 crystallisation Methods 0.000 claims abstract description 27
- 230000008025 crystallization Effects 0.000 claims abstract description 27
- 238000001035 drying Methods 0.000 claims abstract description 25
- 239000003795 chemical substances by application Substances 0.000 claims abstract description 23
- 238000002156 mixing Methods 0.000 claims abstract description 19
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims abstract description 16
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 16
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 16
- 229910004298 SiO 2 Inorganic materials 0.000 claims abstract description 15
- 239000011148 porous material Substances 0.000 claims abstract description 15
- 239000003153 chemical reaction reagent Substances 0.000 claims abstract description 11
- 230000007613 environmental effect Effects 0.000 claims abstract description 6
- 230000003113 alkalizing effect Effects 0.000 claims abstract description 5
- 239000003929 acidic solution Substances 0.000 claims abstract description 4
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 26
- 239000008367 deionised water Substances 0.000 claims description 26
- 229910021641 deionized water Inorganic materials 0.000 claims description 26
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 24
- 239000007787 solid Substances 0.000 claims description 22
- 238000001354 calcination Methods 0.000 claims description 21
- 239000007788 liquid Substances 0.000 claims description 19
- 230000020477 pH reduction Effects 0.000 claims description 19
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 18
- 238000003756 stirring Methods 0.000 claims description 16
- 238000001994 activation Methods 0.000 claims description 15
- 239000002253 acid Substances 0.000 claims description 13
- 230000032683 aging Effects 0.000 claims description 13
- 239000011780 sodium chloride Substances 0.000 claims description 13
- WMFOQBRAJBCJND-UHFFFAOYSA-M Lithium hydroxide Chemical compound [Li+].[OH-] WMFOQBRAJBCJND-UHFFFAOYSA-M 0.000 claims description 12
- 230000004913 activation Effects 0.000 claims description 11
- 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 8
- 238000000746 purification Methods 0.000 claims description 8
- 239000003599 detergent Substances 0.000 claims description 7
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 6
- 239000000843 powder Substances 0.000 claims description 4
- 239000007864 aqueous solution Substances 0.000 claims description 3
- 239000003814 drug Substances 0.000 claims description 3
- 239000012847 fine chemical Substances 0.000 claims description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 abstract description 9
- 229910052710 silicon Inorganic materials 0.000 abstract description 9
- 239000010703 silicon Substances 0.000 abstract description 9
- 230000015572 biosynthetic process Effects 0.000 abstract description 4
- 238000003786 synthesis reaction Methods 0.000 abstract description 4
- 238000001914 filtration Methods 0.000 description 22
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 description 22
- 239000005995 Aluminium silicate Substances 0.000 description 17
- 235000012211 aluminium silicate Nutrition 0.000 description 17
- 229910052500 inorganic mineral Inorganic materials 0.000 description 17
- 239000011707 mineral Substances 0.000 description 17
- 239000000126 substance Substances 0.000 description 16
- 235000012216 bentonite Nutrition 0.000 description 15
- 229910000278 bentonite Inorganic materials 0.000 description 14
- 239000000440 bentonite Substances 0.000 description 14
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 description 14
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 9
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 8
- 239000000203 mixture Substances 0.000 description 8
- 238000001179 sorption measurement Methods 0.000 description 8
- 230000008569 process Effects 0.000 description 7
- 239000000047 product Substances 0.000 description 7
- 239000002689 soil Substances 0.000 description 7
- 238000002441 X-ray diffraction Methods 0.000 description 6
- 238000005265 energy consumption Methods 0.000 description 6
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 239000002245 particle Substances 0.000 description 6
- 238000004458 analytical method Methods 0.000 description 5
- 238000001816 cooling Methods 0.000 description 5
- 238000001514 detection method Methods 0.000 description 5
- 239000000463 material Substances 0.000 description 5
- 230000007935 neutral effect Effects 0.000 description 5
- 238000000643 oven drying Methods 0.000 description 5
- 239000010457 zeolite Substances 0.000 description 5
- 229910021536 Zeolite Inorganic materials 0.000 description 4
- 239000004927 clay Substances 0.000 description 4
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 125000005842 heteroatom Chemical group 0.000 description 4
- 239000012535 impurity Substances 0.000 description 4
- 238000005342 ion exchange Methods 0.000 description 4
- 229910010413 TiO 2 Inorganic materials 0.000 description 3
- 239000003463 adsorbent Substances 0.000 description 3
- 239000003054 catalyst Substances 0.000 description 3
- 239000002734 clay mineral Substances 0.000 description 3
- 239000002274 desiccant Substances 0.000 description 3
- GUJOJGAPFQRJSV-UHFFFAOYSA-N dialuminum;dioxosilane;oxygen(2-);hydrate Chemical compound O.[O-2].[O-2].[O-2].[Al+3].[Al+3].O=[Si]=O.O=[Si]=O.O=[Si]=O.O=[Si]=O GUJOJGAPFQRJSV-UHFFFAOYSA-N 0.000 description 3
- 239000008233 hard water Substances 0.000 description 3
- 238000005216 hydrothermal crystallization Methods 0.000 description 3
- 229910052622 kaolinite Inorganic materials 0.000 description 3
- 230000004048 modification Effects 0.000 description 3
- 238000012986 modification Methods 0.000 description 3
- 229910052901 montmorillonite Inorganic materials 0.000 description 3
- 235000012239 silicon dioxide Nutrition 0.000 description 3
- 239000003516 soil conditioner Substances 0.000 description 3
- 239000002699 waste material Substances 0.000 description 3
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical group [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 2
- CSDREXVUYHZDNP-UHFFFAOYSA-N alumanylidynesilicon Chemical compound [Al].[Si] CSDREXVUYHZDNP-UHFFFAOYSA-N 0.000 description 2
- 229910001570 bauxite Inorganic materials 0.000 description 2
- 239000011575 calcium Substances 0.000 description 2
- 238000006555 catalytic reaction Methods 0.000 description 2
- 229940079593 drug Drugs 0.000 description 2
- 239000010433 feldspar Substances 0.000 description 2
- 238000001027 hydrothermal synthesis Methods 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000007431 microscopic evaluation Methods 0.000 description 2
- -1 nacrite Inorganic materials 0.000 description 2
- 229910052755 nonmetal Inorganic materials 0.000 description 2
- 239000010453 quartz Substances 0.000 description 2
- 230000035484 reaction time Effects 0.000 description 2
- 239000004576 sand Substances 0.000 description 2
- 238000001878 scanning electron micrograph Methods 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 230000002194 synthesizing effect Effects 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- 229910021532 Calcite Inorganic materials 0.000 description 1
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical group [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 1
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical group [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 238000010306 acid treatment Methods 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 239000002535 acidifier Substances 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 229910000323 aluminium silicate Inorganic materials 0.000 description 1
- HPTYUNKZVDYXLP-UHFFFAOYSA-N aluminum;trihydroxy(trihydroxysilyloxy)silane;hydrate Chemical compound O.[Al].[Al].O[Si](O)(O)O[Si](O)(O)O HPTYUNKZVDYXLP-UHFFFAOYSA-N 0.000 description 1
- 229960000892 attapulgite Drugs 0.000 description 1
- 239000012752 auxiliary agent Substances 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 229910001424 calcium ion Inorganic materials 0.000 description 1
- VNSBYDPZHCQWNB-UHFFFAOYSA-N calcium;aluminum;dioxido(oxo)silane;sodium;hydrate Chemical compound O.[Na].[Al].[Ca+2].[O-][Si]([O-])=O VNSBYDPZHCQWNB-UHFFFAOYSA-N 0.000 description 1
- 229910001748 carbonate mineral Inorganic materials 0.000 description 1
- 230000003197 catalytic effect Effects 0.000 description 1
- 238000005341 cation exchange Methods 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 239000004568 cement Substances 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 239000013064 chemical raw material Substances 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 239000011362 coarse particle Substances 0.000 description 1
- 239000002178 crystalline material Substances 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 229910001649 dickite Inorganic materials 0.000 description 1
- 238000010292 electrical insulation Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 239000010881 fly ash Substances 0.000 description 1
- 238000000227 grinding Methods 0.000 description 1
- 229910052621 halloysite Inorganic materials 0.000 description 1
- 238000003837 high-temperature calcination Methods 0.000 description 1
- 229910052900 illite Inorganic materials 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 239000004615 ingredient Substances 0.000 description 1
- 239000013385 inorganic framework Substances 0.000 description 1
- 238000003475 lamination Methods 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 239000002075 main ingredient Substances 0.000 description 1
- VGIBGUSAECPPNB-UHFFFAOYSA-L nonaaluminum;magnesium;tripotassium;1,3-dioxido-2,4,5-trioxa-1,3-disilabicyclo[1.1.1]pentane;iron(2+);oxygen(2-);fluoride;hydroxide Chemical compound [OH-].[O-2].[O-2].[O-2].[O-2].[O-2].[F-].[Mg+2].[Al+3].[Al+3].[Al+3].[Al+3].[Al+3].[Al+3].[Al+3].[Al+3].[Al+3].[K+].[K+].[K+].[Fe+2].O1[Si]2([O-])O[Si]1([O-])O2.O1[Si]2([O-])O[Si]1([O-])O2.O1[Si]2([O-])O[Si]1([O-])O2.O1[Si]2([O-])O[Si]1([O-])O2.O1[Si]2([O-])O[Si]1([O-])O2.O1[Si]2([O-])O[Si]1([O-])O2.O1[Si]2([O-])O[Si]1([O-])O2 VGIBGUSAECPPNB-UHFFFAOYSA-L 0.000 description 1
- 231100000956 nontoxicity Toxicity 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 238000007500 overflow downdraw method Methods 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052625 palygorskite Inorganic materials 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 229910052903 pyrophyllite Inorganic materials 0.000 description 1
- 230000036632 reaction speed Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 238000004626 scanning electron microscopy Methods 0.000 description 1
- 238000012216 screening Methods 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 1
- LIVNPJMFVYWSIS-UHFFFAOYSA-N silicon monoxide Chemical compound [Si-]#[O+] LIVNPJMFVYWSIS-UHFFFAOYSA-N 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000013589 supplement Substances 0.000 description 1
- 230000001502 supplementing effect Effects 0.000 description 1
- 238000009210 therapy by ultrasound Methods 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 239000005335 volcanic glass Substances 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B39/00—Compounds having molecular sieve and base-exchange properties, e.g. crystalline zeolites; Their preparation; After-treatment, e.g. ion-exchange or dealumination
- C01B39/02—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
- C01B39/18—Type A from a reaction mixture containing at least one aluminium silicate or aluminosilicate of a clay type, e.g. kaolin or metakaolin or its exotherm modification or allophane
-
- 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
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- 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
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/12—Surface area
-
- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- C01P2006/00—Physical properties of inorganic compounds
- C01P2006/14—Pore volume
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- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geology (AREA)
- Organic Chemistry (AREA)
- Dispersion 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 provides a loess-based 4A molecular sieve, a preparation method and application thereof, and relates to the technical field of synthesis of loess-based molecular sieves. The method specifically comprises the following steps: (1) purifying: washing and drying loess in northwest region with water to obtain purified loess; (2) sodium treatment: mixing the sodium treatment agent solution and the purified loess uniformly to obtain sodium treated loess; (3) acidifying: adding an acidic solution into the sodium loess to obtain acidified loess; (4) alkalization: alkalizing the acidified loess to obtain alkalized loess; (5) and (3) crystallization: replenishing an aluminum source, an alkali source and water to ensure that the molar ratio of the raw materials in the slurry is SiO 2 ∶Al 2 O 3 ∶H 2 O to NaOH = 1-2, 1 to 210-230 and 13-15; adding 4A molecular sieve seed crystal, and carrying out crystallization reaction to obtain the product. According to the method, the loess is used as the raw material to prepare the 4A molecular sieve, reagents such as a silicon source, an organic template agent and the like are not required to be added, and the method has the advantages of simple steps, mild conditions, environmental friendliness and the like. The obtained 4A molecular sieve is in a cage-shaped spherical structure and has the characteristics of high specific surface area and large total pore volume.
Description
Technical Field
The invention belongs to the technical field of synthesis of loess-based molecular sieves, and particularly relates to a loess-based 4A-type molecular sieve and a preparation method and application thereof.
Background
The loess resources in northwest are extremely rich, the sources are the widest in the wind, and the loess is considered to come from the north and northwest of the arid desert areas such as Gansu, ningxia, xinjiang, mongolian plateau and middle Asia. The coarse stones remain in situ to become gobi, and the fine sand particles fall into nearby areas and are gathered into a piece of desert; the fine silt and clay are blown far away to form a loess plateau. Loess in northwest region is a complex mineral with a mixture of multiple mineral crystals and has a complex composition, and contains abundant metal or nonmetal oxide, siO 2 And Al 2 O 3 The contents of which respectively account for 57.1-60 percent and 13.87-11.8 percent of the total weight, and Fe is secondly 2 O 3 And CaO in an amount of 4.1-5.67% and 1.30-8.35%, respectively. Although the loess contains abundant metal or nonmetal oxides, the loess resource is not fully developed and utilized so far, which causes resource waste; the wind blows the sand to cause environmental pollution. If the loess can be changed into useful chemical raw materials or chemical products, the loess is economical and environment-friendly, and the cost of some chemical raw materials and products can be greatly reduced.
Structurally, loess in northwest region generally consists of clastic minerals and clay minerals, wherein the clastic minerals account for more than 70%. The microstructure is formed by mutual support of large mineral particles, and a plurality of fine particles are attached to the surfaces of the large particles to form a loess structure which takes the macroporous structure of the support as a main part and takes the semi-conglutination of the embedded micropores as a secondary part. The clay mineral component in loess mainly comprises hydromica, kaolinite and montmorillonite. The presence of these minerals imparts properties such as adsorption, expansion, and shrinkage to the loess, which affects its engineering properties. Carbonate minerals tend to act as a cement, causing the loess to often exist as aggregates in the case of natural structures. The particle size of the loess is generally between 0.05-0.005 mm, wherein the content of coarse particles (0.05-0.01 mm) is more than 50%; the particle size of the clay particles is about 0.25 mm. The loess also has high porosity, generally 33-64%, and generally has tubular pores with the pore diameter as large as 0.5-1 cm, and the pores are filled with carbonate with different amount.
To understand the structure and properties of loess in more detail, the inventors compared bentonite and kaolin, which seemed to have similar structures, with loess. Bentonite, also known as bentonite or bentonite, was first found in ancient strata in wyoming, usa as a yellow-green clay; clays of this nature are collectively referred to as bentonites because they swell to a paste when water is added. The bentonite comprises montmorillonite as main ingredient and Al as chemical component 2 ,Mg 3 )Si 4 O 10 OH 2 ·nH 2 O, the content is 85-90%, and a small amount of feldspar, quartz, beidellite, calcite, volcanic glass and the like are also contained.
Kaolin is a non-metallic mineral, clay and claystone based on clay minerals of the kaolinite group. The name is obtained from Kaolin village in Jingdezhen of Jiangxi province. Kaolin is generally composed of a mineral reserve of kaolinite clusters (kaolinite, dickite, nacrite, halloysite, etc.) of less than 2 micron fine flakes, tubes, laminations, etc., and has the chemical formula AL 2 O 3 ·2SiO 2 ·2H 2 And O, the main mineral ingredients of the mineral comprise montmorillonite, illite, pyrophyllite, quartz, feldspar and other mineral accompanying parts besides the kaolinite cluster mineral. Meanwhile, the chemical composition of the kaolin contains a plurality of AL 2 O 3 、SiO 2 And a small amount of Fe 2 O 3 、TiO 2 And a trace amount of K 2 O、Na 2 O, caO and MgO, etc. The pure kaolin has high whiteness, is soft, is easy to disperse and suspend in water, and has high cohesiveness, excellent electrical insulation, good plasticity, acid solubility resistance, very low cation exchange capacity, good fire resistance and other physicochemical properties. The biggest difference between bentonite and kaolin is that kaolin, although viscous, is very different from bentonite in composition and kaolin does not have swellability.
Analysis shows that although loess, bentonite and kaolin look similar, the loess, bentonite and kaolin have great differences in structure, chemical components and physical and chemical properties. Compared with the structures of bentonite and kaolin, the structure of loess is more complex, and the types of mineral crystals are more; meanwhile, the chemical compositions of the loess, loess powder and loess are different, the chemical compositions are more complex, and more impurities influence the performance of subsequent products; in addition, the three types of soils have different crystal structures, and the physical and chemical properties of the soils are different from each other. However, these three kinds of soils have some common points, for example, they all exhibit a certain crystal structure. Therefore, if the loess is converted into the 4A molecular sieve by appropriate modification treatment with reference to the application of bentonite and kaolin, the utilization rate of the loess can be greatly improved, and the 4A molecular sieve can be produced on a large scale, so that the cost of the 4A molecular sieve is reduced.
Molecular sieves, also known as zeolites, are porous crystalline materials of aluminosilicates or aluminophosphates having an inorganic framework. The chemical formula is (M' 2 M)O·Al 2 O 3 ·xSiO 2 ·yH 2 O, wherein M', M are each independently a monovalent or divalent cation, e.g. K + 、Na + And Ca 2 + 、Ba 2+ And so on. Due to the unique pore channel structure inside the zeolite, the zeolite has excellent properties of catalysis, ion exchange, selective adsorption, stain resistance and the like, and is widely applied to the fields of industrial processes of adsorption separation, washing, catalysis and the like and high-tech materials. Meanwhile, due to the non-toxicity, non-pollution and good stability of the material, the zeolite becomes an important mineral resource and chemical raw material. The synthesis of the molecular sieve usually adopts a hydrothermal synthesis method, and the used raw materials are chemical reagents containing silicon sources and aluminum sources and template agents to synthesize the molecular sieve.
The 4A type molecular sieve is a sodium type molecular sieve with an A type structure, and the aperture is 4 angstroms. The framework structure is a cubic crystal system structure formed by beta cages and cubes, and two adjacent beta cages are mutually connected by four oxygen bridges through a four-membered ring to form a main cage-alpha cage of the A-type zeolite, so that the crystal structure of the A-type molecular sieve is obtained. The 4A type molecular sieve can be used as a detergent auxiliary agent, a hard water softener, a separating agent, a catalyst, a drying agent, an adsorbent, a soil conditioner and the like.
At present, there are many methods for preparing 4A type molecular sieves by using bentonite and kaolin which are added with silicon and aluminum sources or natural silicon and aluminum sources as raw materials. Patent CN201210518340.4 discloses a method for preparing 4A type molecular sieve by using bauxite tailings as raw material, but the bauxite tailings contain a large amount of aluminum, a small amount of silicon and iron, and when preparing the 4A type molecular sieve, iron is removed and a large amount of silicon raw material is added; meanwhile, in the alkalization process, calcination needs to be carried out at 500-600 ℃, so that the energy consumption is high, and in addition, the raw material source is limited, and large-scale production cannot be realized. Patent CN201811272197.9 discloses a method for preparing a single crystalline phase 4A molecular sieve by using residue from extraction of aluminum from fly ash as a raw material and using an alkali fusion-hydrothermal synthesis method. The method requires calcination at 800 deg.C, and has high energy consumption. The patent CN99118246.4 discloses a new process for synthesizing a 4A molecular sieve by a kaolin alkali fusion method, which comprises the steps of mixing and grinding kaolin and alkali uniformly, calcining, extracting with water, gelling and crystallizing to synthesize the 4A molecular sieve. The calcium exchange capacity of the calcium carbonate reaches 310mgCaCO 3 Per gram of molecular sieve. The method requires calcination at 600 ℃ and has limited raw material sources, which cannot be mass-produced for a long time. Patent CN201210006471.4 discloses a method for synthesizing 4A molecular sieve by using bentonite and attapulgite as raw materials and utilizing SiO therein 2 4A molecular sieves suitable for use in detergent additives are prepared as a silicon source. The method needs calcination at 800 ℃, and has complex treatment process and limited raw material sources.
Therefore, the above prior art solutions all have the problems of too high calcination temperature, limited raw material sources, etc., and therefore, how to overcome the above technical problems is to prepare a 4A molecular sieve with a high specific surface area and a large total pore volume by using loess as a raw material through a low energy consumption method is a problem to be solved by those skilled in the art.
Disclosure of Invention
The invention aims to provide a preparation method of a loess-based 4A type molecular sieve, which takes loess produced in northwest China as a raw material, fully utilizes silicon-aluminum components in the loess through the processes of purification, sodium treatment, acidification, alkaline activation, medium-low temperature hydrothermal crystallization and the like, supplements a certain amount of aluminum source to ensure that the silicon-aluminum ratio in the raw material is (1-2) to 1, and can prepare the 4A type molecular sieve after hydrothermal crystallization.
The preparation method does not use a high-temperature calcination process, does not need reagents such as a silicon source and an organic template agent, and has the advantages of simple steps, mild conditions, low cost, environmental friendliness and the like. The preparation method is simple and easy to implement, has wide and sufficient raw material sources, is particularly suitable for large-scale industrial production and preparation, can really realize resource utilization of the loess, and can relieve the problems of water and soil loss, ecological fragility and the like of the loess plateau.
In order to achieve the above object, the present invention provides a method for preparing a loess-based 4A type molecular sieve, which comprises the following steps:
purification: washing and drying loess in northwest region with water to obtain purified loess;
sodium treatment: mixing the sodium treatment agent solution and the purified loess uniformly, and carrying out sodium treatment reaction to obtain sodium-treated loess;
acidifying: adding an acid solution into the sodium loess, and carrying out an acidification reaction to obtain acidified loess;
alkalization: alkalizing the acidified loess to obtain alkalized loess, wherein the alkalization comprises any one of dry activation method or wet activation method;
and (3) crystallization: detecting the components of the alkalized loess, replenishing an aluminum source, an alkali source and water to ensure that the molar ratio of the raw materials in the slurry is SiO 2 ∶Al 2 O 3 ∶H 2 O: naOH = (1-2): 1: (210-230): 13-15); adding 4A molecular sieve seed crystal, aging at room temperature, transferring into a closed reaction kettle, and performing crystallization reaction to obtain the Huang Tuji A type molecular sieve.
In a preferred embodiment, the loess has a silica-alumina molar ratio of SiO 2 ∶Al 2 O 3 ＝(6.8～8.8)：1。
In a preferred embodiment, in the sodium treatment step, the preparation method of the sodium treatment agent solution comprises the following steps: uniformly mixing a sodium reagent and deionized water to obtain an aqueous solution with the mass concentration of 20-60%; the sodium reagent is selected from NaCO 3 One or more of NaCl and NaF; the solid-liquid ratio of the purified loess to the sodium treatment agent solution is 1: (3-6), wherein the sodium treatment reaction conditions are as follows: reacting for 2-6 h at 70-100 ℃.
In a preferred embodiment, in the acidification step, the acidic solution is sulfuric acid with a mass concentration of 20-50%; the solid-liquid ratio of the sodium loess to the acid solution is 1: (3-6); the acidification reaction conditions are as follows: stirring and reacting for 8-24 h at the temperature of 80-95 ℃.
In a preferred embodiment, in the alkalization step, the dry activation process comprises the steps of: uniformly mixing the acidified loess with the alkali source solid powder, and calcining to obtain dry-method alkalized loess; the calcination temperature is 300-400 ℃, and the calcination time is 1-5 h.
In a preferred embodiment, in the alkalization step, the wet activation process comprises the steps of: uniformly mixing the alkali source solid with deionized water to obtain an alkali source solution with the mass concentration of 5-50%, adding acidified loess into the alkali source solution, and stirring at the temperature of 70-95 ℃ for 2-8 h to obtain the wet-process alkalized loess.
In a preferred embodiment, in the alkalization step, the alkali-derived solid is selected from one or more of NaOH, KOH and LiOH, and the mass ratio of the acidified loess to the alkali-derived solid is 1: (0.5-2).
In a preferred embodiment, in the crystallization step, the aluminum source is one or more of aluminum sulfate and sodium metaaluminate; the alkali source is one or more of NaOH, KOH and LiOH; the adding amount of the 4A molecular sieve seed crystal is 2-5% of the mass of the slurry; the aging time is 6-12 h; the crystallization temperature is 90-100 ℃, and the crystallization time is 3-8 h.
Another object of the present invention is to provide a loess-based 4A type molecular sieve, which has a structure significantly different from a conventional cubic structure in the prior art, and has a larger specific surface area and pore volume, thereby effectively improving the adsorption effect of the 4A molecular sieve. On the other hand, the microstructure of the cage-shaped sphere also enriches the types of the 4A molecular sieve, provides more application scenes, and provides a research direction for further improving the performance of the 4A molecular sieve.
In a preferred embodiment, the Huang Tuji A type molecular sieve is in a cage-shaped sphere structure, and the specific surface area is 50-60 m 2 The total pore volume is 0.0250-0.0350 cm 3 /g。
The invention also aims to provide application of the loess-based 4A molecular sieve, and the prepared loess-based 4A molecular sieve can be widely applied to the fields of detergent industry, water treatment, fine chemical industry, environmental protection, petrochemical industry, medicines and the like.
In a preferred embodiment, the obtained loess-based 4A molecular sieve can be used as a detergent auxiliary, a hard water softener, a separating agent, a catalyst, a drying agent, an adsorbent and a soil conditioner.
Compared with the prior art, the technical scheme of the invention has the following advantages:
(1) In the method for preparing the 4A type molecular sieve based on the loess in the northwest region, the high-purity 4A type molecular sieve crystal can be obtained by only carrying out the steps of sodium treatment, acidification, alkalization and the like on the raw material of the loess, supplementing a small amount of aluminum source, alkali source and water, crystallizing in a reaction kettle, washing and drying.
(2) In the preparation method of the 4A-type molecular sieve provided by the invention, loess of the loess plateau is used as a raw material, and the effective components of silicon and aluminum in the loess are fully utilized, so that the resource utilization of the loess is really realized, and the smooth transformation of the invention is expected to relieve and even improve the environmental problems of water and soil loss, ecological weakness and the like in the loess plateau area, and has great ecological environment application value.
(3) The loess-based 4A type molecular sieve prepared by the invention has obviously increased specific surface area which is 50-60 m 2 The total pore volume is 0.0250-0.0350 cm 3 The calcium ion exchange capacity is 301.2-332.8mg/g through actual detection.
(4) When the loess-based 4A type molecular sieve is prepared, the 4A type molecular sieve can be obtained by any method provided by the alkalization step, wherein the calcination temperature of the dry alkalization method is only 400 ℃, the stirring reaction can be carried out at about 90 ℃ by the wet alkalization method, and the reaction temperature and the energy consumption can be greatly reduced.
(5) The Huang Tuji A type molecular sieve is prepared by using the loess as the raw material, and the raw material has the advantages of wide source, convenience in collection and huge storage capacity, so that the raw material purchasing cost can be greatly reduced; from the process, the method has the advantages of low energy consumption requirement of the steps, high preparation safety and effective control of production cost; in addition, the sodium agent, the acidifying agent, the alkalizing agent and the like used in the processing process can be recycled, so that the waste liquid discharge is reduced, and the preparation cost can be further reduced.
Drawings
These and/or other aspects and advantages of the present invention will become more apparent and more readily appreciated from the following detailed description of the embodiments of the invention, taken in conjunction with the accompanying drawings of which:
fig. 1 is an XRD pattern of the type 4A molecular sieve, the standard 4A molecular sieve and the loess raw material prepared in example 1.
Fig. 2 and 3 are SEM images of the type 4A molecular sieve prepared in example 1 at different resolutions.
Fig. 4 is a BET diagram of the 4A type molecular sieve, loess raw material, sodiated loess, and alkalized loess prepared in example 1.
Detailed Description
In order that those skilled in the art will better understand the present invention, the following detailed description is given with reference to the accompanying drawings and the specific embodiments, but it should be understood that the scope of the present invention is not limited by the specific embodiments.
The embodiment of the invention provides a loess-based 4A molecular sieve, and a preparation method and application thereof, and solves the problems that the 4A molecular sieve cannot be prepared by taking loess as a raw material and the 4A molecular sieve with a cage-shaped spherical structure cannot be synthesized in the prior art.
In order to solve the problems, the technical scheme of the invention has the following general idea:
the invention aims to provide a preparation method of a loess-based 4A type molecular sieve, which comprises the following steps:
purifying: washing and drying loess in northwest region with water to obtain purified loess;
sodium treatment: mixing the sodium treatment agent solution and the purified loess uniformly, and performing sodium treatment reaction to obtain sodium-treated loess;
acidifying: adding an acid solution into the sodium loess, and carrying out an acidification reaction to obtain acidified loess;
alkalization: alkalizing the acidified loess to obtain alkalized loess, wherein the alkalization comprises any one of dry activation method or wet activation method;
and (3) crystallization: detecting the components of the alkalized loess, and replenishing an aluminum source, an alkali source and water to ensure that the molar ratio of the raw materials in the slurry is SiO 2 ∶Al 2 O 3 ∶H 2 O: naOH = (1-2): 1: (210-230): 13-15); adding 4A molecular sieve seed crystal, aging at room temperature, transferring into a closed reaction kettle, and performing crystallization reaction to obtain the Huang Tuji A type molecular sieve.
In a preferred embodiment, in the purification step, the loess has a silica-alumina molar ratio of SiO 2 ∶Al 2 O 3 = (6.8 to 8.8): 1. the contents of main components of the loess used in the present invention are shown in table 1, and it can be seen from table 1 that the silica alumina ratio in the loess is greatly different from that in bentonite and kaolin, and the components in the loess are more complicated. Therefore, the subsequent steps of the method take the loess as the raw material to carry out targeted optimization and improvement, thereby fully utilizing the silica-alumina molar ratio of the loess and reducing the influence of other components.
In a preferred embodiment, in the purification step, the washing and drying conditions may be any manner known to those skilled in the art, as long as impurities can be removed, and preferably, the washing step is performed by washing with deionized water, filtering with a 200-mesh sieve, repeating the washing step for 3-5 times, and drying at 100-120 ℃ for 1-2 h.
In a preferred embodiment, in the sodium treatment step, the preparation method of the sodium treatment agent solution is as follows: uniformly mixing a sodium reagent and deionized water to obtain an aqueous solution with the mass concentration of 20-60%, preferably, the mass concentration of the sodium reagent solution is 30-40%; the sodium reagent is selected from NaCO 3 NaCl and NaF. Purpose of sodium treatmentMainly replaces metal heteroatoms in the loess, and prevents the following metal heteroatoms from influencing the catalytic effect and the ion exchange effect of the Huang Tuji A molecular sieve.
In a preferred embodiment, in the sodium treatment step, the solid-to-liquid ratio of the purified loess to the sodium treatment agent solution is 1: 3-6, and the sodium treatment reaction conditions are as follows: reacting for 2 to 6 hours at the temperature of 70 to 100 ℃, and preferably, carrying out sodium treatment under the following reaction conditions: reacting for 4-5 h at 80-90 ℃. Under the conditions of the reaction temperature and the reaction time, the reaction speed is high, and the energy is saved. Meanwhile, the solid-liquid ratio of 1 to (3-6) is selected mainly to ensure a better reaction effect and reduce the discharge amount of sewage.
In a preferred embodiment, in the acidification step, the acidic solution is sulfuric acid with a mass concentration of 20 to 50%, preferably, the sulfuric acid concentration is 30%; the solid-liquid ratio of the sodium loess to the acid solution is 1: 3-6, preferably 1:3, 1:4 and 1:5; the acidification reaction conditions are as follows: stirring and reacting for 8-24 h at the temperature of 80-95 ℃, and preferably, the acidification reaction conditions are as follows: stirring and reacting for 12-18 h at 85-90 ℃.
The purpose of acidification is that the loess has a more complex silicate structure and chemical composition for removing SiO 2 、Al 2 O 3 In addition, it also contains Fe 2 O 3 、CaO、MgO、TiO 2 And the like; due to Fe in loess 2 O 3 、TiO 2 And the existence of impurities, the whiteness of the synthesized molecular sieve product is lower; the loess after acid treatment can remove most of Mg, fe, ti and other impurities, destroy the crystal structure of the soil layer, dissolve out partial aluminum and obtain amorphous activated silica-alumina gel, so that the purity of the synthesized loess-based 4A molecular sieve can be greatly improved after the loess is acidified.
In addition, the method uses sulfuric acid for acidification, so that the purpose of acidification can be achieved, chlorine-containing waste liquid is avoided, the environment is polluted, and sulfate radicals are not generated after the loess is treated by the sulfuric acid to influence the subsequent applications of the 4A molecular sieve, such as ion exchange and the like.
The purpose of sodium treatment and acidification is that if the treatment sequence is reversed, a large amount of metal heteroatoms and sulfuric acid can generate a large amount of slightly soluble or insoluble sulfate in acidification, the subsequent sodium treatment effect can be affected, and the application of the loess-based 4A molecular sieve is finally affected. Sodium treatment will not replace a large amount of metal heteroatoms in the loess. Therefore, the present invention performs the treatment in the order of sodium treatment and acidification.
In a preferred embodiment, in the alkalization step, the dry activation process comprises the steps of: uniformly mixing the acidified loess with alkali source solid powder, and calcining to obtain dry-method alkalized loess; the calcination temperature is 300-400 ℃, the calcination time is 1-5 h, preferably, the calcination temperature is 400 ℃, and the calcination time is 3-4 h.
In a preferred embodiment, in the alkalization step, the wet activation process comprises the steps of: uniformly mixing the alkali source solid with deionized water to obtain an alkali source solution with the mass concentration of 5-50%, preferably 20-30%; adding acidified loess into the alkali source solution, stirring at 800-1000 rpm at 70-95 deg.C for 2-8 h to obtain wet-process alkalized loess, preferably stirring at 800-1000 rpm at 75-90 deg.C for 4-6 h.
In a preferred embodiment, in the alkalization step, the alkali source solid is selected from one or more of NaOH, KOH and LiOH, and the mass ratio of the acidified loess to the alkali source solid is 1 to (0.5-2), and preferably, the mass ratio of the acidified loess to the alkali source solid is 1 to (1-1.5).
The alkali activation aims to destroy the crystal structure of silicate in loess, so that silicon oxide crystal is dissolved out of loess to become amorphous active silica sol. When the alkalization step is completed, in order to achieve crystallization reaction conditions, a small amount of alkali source needs to be added in the crystallization step, so that the reaction can achieve the crystallization pH reaction conditions.
The invention provides two alkalization methods which can achieve the purpose of the invention. The dry alkalization method has the advantages of short alkalization time, complete reaction, great damage to the stable structure of the silicon dioxide in the loess, calcination temperature of only 400 ℃, and great reduction of energy consumption compared with the prior art. The wet alkalization method can further reduce the reaction temperature and improve the safety of the preparation process.
In a preferred embodiment, in the crystallization step, the aluminum source is one or more of aluminum sulfate and sodium metaaluminate; the alkali source is one or more of NaOH, KOH and LiOH; the adding amount of the 4A molecular sieve seed crystal is 2-5% of the total mass of the slurry, and preferably, the adding amount of the 4A molecular sieve seed crystal is 2-3% of the total mass of the slurry; the aging time is 6-12 h; the crystallization temperature is 90-100 ℃, the crystallization time is 3-8 h, preferably, the crystallization temperature is 90 ℃, and the crystallization time is 4-6 h.
In a preferred embodiment, in the crystallization step, the slurry PH is 12 to 13.
In a preferred embodiment, in the crystallization step, the raw material molar ratio in the slurry is SiO 2 ∶Al 2 O 3 ∶H 2 O∶NaOH＝1.9∶1∶215∶13。
The purpose of aging at room temperature is that aging increases the number of crystal nuclei in the slurry system, thereby reducing the crystallization reaction time and making the loess more likely to form the 4A molecular sieve. In addition, the larger the number of nuclei, the higher the yield of Huang Tuji A molecular sieve.
In a preferred embodiment, after the crystallization reaction is finished, the method further comprises filtering, collecting the solid, washing to a pH of 9, and drying. The washing is a conventional operation known to those skilled in the art, and the product is generally washed 1 to 2 times with acidic water having a pH of 2 to 4; the product was then washed 2-5 times with deionized water to a pH =9 or so. Preferably, when washing, ultrasonic treatment can be carried out to obtain a high-quality 4A type molecular sieve product with clean surface. The drying condition can be any equipment and method known by the technical personnel in the field, and the drying is preferably carried out for 6 to 18 hours at the temperature of 80 to 120 ℃.
Another object of the present invention is to provide a loess-based 4A type molecular sieve.
The loess-based 4A type molecular sieve prepared by the invention is of a cage-shaped sphere structure, and the specific surface area is 50-60 m 2 The total pore volume is 0.0250-0.0350 cm 3 /g。
The invention also aims to provide application of the loess-based 4A molecular sieve, and the prepared loess-based 4A molecular sieve can be widely applied to the fields of detergent industry, water treatment, fine chemical industry, environmental protection, petrochemical industry, medicines and the like.
In a preferred embodiment, the obtained loess-based 4A molecular sieve can be used as a detergent auxiliary, a hard water softener, a separating agent, a catalyst, a drying agent, an adsorbent and a soil conditioner.
The technical scheme of the application is explained in detail by specific embodiments as follows:
the technical means used in the present invention are conventional means well known to those skilled in the art, and various raw materials, reagents, instruments, equipment and the like used in the present invention can be commercially available or can be prepared by existing methods, if not specifically indicated. In the present invention, the room temperature is 25 ℃.
In the embodiment of the invention, the loess is produced in northwest China, and particularly from Qingyang city of Gansu province. Compared with other soils and raw materials, loess has the advantages of abundant resources, no limitation of raw materials and the like, but has a complex crystal structure and a plurality of components, and the synthesis and the performance of the molecular sieve are influenced by the mixed crystal components. The results of the loess chemical composition analysis are shown in Table 1.
Table 1: loess main component content
Example 1
Purification: washing loess raw material with deionized water, filtering with 200 mesh sieve, repeating for 3-5 times, and oven drying at 120 deg.C for 2 hr. Obtaining purified loess;
sodium treatment, namely preparing a NaCl solution with the mass concentration of 30% by taking NaCl as a sodium treatment agent, adding 100.0g of purified loess to ensure that the solid-liquid ratio is 1:4, stirring for 5 hours at 90 ℃, filtering, washing and drying at 120 ℃ to obtain the sodium-treated loess;
acidifying, namely preparing dilute sulfuric acid with the mass concentration of 30%, adding 50g of the sodium loess, keeping the solid-liquid ratio at 1:4, acidifying at 90 ℃ for 15h, filtering, washing to be neutral, and drying at 120 ℃ to obtain the acidified loess.
Dry alkalization, namely uniformly mixing 20g of acidified loess and 22g of sodium hydroxide solid, calcining for 3h at 400 ℃, and cooling to room temperature for later use.
20g of dry alkalized loess is taken, 26.59g of aluminum sulfate, 17.5g of sodium hydroxide and 203g of deionized water are added and stirred evenly to ensure that the raw material mol ratio in the slurry is SiO 2 ∶Al 2 O 3 ∶H 2 Adding 4A molecular sieve seed crystal with the addition amount of 2% of the mass of the slurry, aging for 9h at room temperature, transferring into a high-pressure reaction kettle, placing into an oven, reacting for 4h at 90 ℃, washing with an acid solution, washing with deionized water until the pH is =9, filtering, and drying at 90 ℃ to obtain the loess-based 4A molecular sieve, wherein the ratio of O to NaOH is = 1.9: 1: 215: 13, and the pH is about = 13.
The characterization and analysis results of the 4A type molecular sieve prepared by the invention are as follows:
1. x-ray diffraction analysis
The X-ray diffraction analysis (XRD) mainly aims at the analysis of crystalline substances in minerals, and the components of the crystalline substances in the minerals and the content of each component can be obtained by analyzing diffraction peaks of an XRD pattern. The present invention performed X-ray diffraction scans of the raw loess material without any treatment, the standard 4A molecular sieve, and the loess-based 4A molecular sieve prepared in example 1 of the present invention at 2 θ of 10 to 80 degrees, and the results are shown in fig. 1.
By contrast, it can be seen from fig. 1 that the raw loess material also exhibits a crystal structure, but is greatly different from that of the standard 4A molecular sieve. The comparison of the loess-based 4A molecular sieve with the standard 4A molecular sieve shows that the peak positions of the characteristic peaks are basically the same, which indicates that the technical scheme of the invention takes the loess as the raw material to successfully prepare the 4A molecular sieve.
2. Microscopic analysis
Microscopic analysis the morphology of the material was observed mainly using Scanning Electron Microscopy (SEM), the results of which are shown in fig. 2 and 3.
As can be seen from the figure, the molecular sieve structure synthesized by the invention consists of a large number of regular cage-shaped spheres, and each cage-shaped sphere is formed by gathering a plurality of strip-shaped bugs together to form a cage-shaped structure. Compared with the conventional cubic structure in the prior art, the molecular sieve prepared by the invention has larger specific surface area and pore diameter, and a large number of gaps are formed in the middle of each cage-shaped sphere in an SEM image, so that the adsorption capacity can be effectively improved.
3. BET specific surface area test
The results of the tests on the loess-based 4A molecular sieve prepared in example 1 were shown in fig. 4, in which the loess raw material without any treatment was subjected to the purification and sodium treatment steps in example 1 to obtain sodium-modified loess, the alkalized loess was obtained in example 1 through the purification, sodium treatment, acidification and dry alkalization steps, and the loess-based 4A molecular sieve prepared in example 1 were subjected to the BET specific surface area analyzer.
As can be seen from FIG. 4, the specific surface area of the loess raw material was as small as 11.18m 2 (g) after acidification and alkalization, the specific surface area is gradually reduced to 3.36m 2 The specific surface area of the molecular sieve is 52.58m after the molecular sieve is converted into Huang Tuji A molecular sieve 2 (iv) g. This is because the purified loess is composed of various mineral crystals, so that it has a certain adsorption force; after acid and alkali activation, the crystal structure is destroyed and changed into an amorphous structure, so that the specific surface area is reduced, the loess is changed into the 4A molecular sieve of the loess through a hydrothermal crystallization method, and the crystal structure with pores is formed again, so that the specific surface area is increased again, and the adsorption force is enhanced.
The analysis shows that the loess-based 4A molecular sieve prepared by the invention has the characteristics of high specific surface area and large aperture, and the microstructure is cage-shaped spheres, so that the loess-based 4A molecular sieve has good adsorption capacity.
Example 2
Purifying: washing loess with deionized water, filtering with 200 mesh sieve, repeating for 3-5 times, and oven drying at 120 deg.C for 2 hr. Obtaining purified loess;
sodium treatment, namely preparing a NaCl solution with the mass concentration of 30% by taking NaCl as a sodium treatment agent, adding 100.0g of purified loess to ensure that the solid-liquid ratio is 1:5, stirring for 5 hours at 90 ℃, filtering, washing and drying at 120 ℃ to obtain the sodium-treated loess;
acidifying, namely preparing dilute sulfuric acid with the mass concentration of 30%, adding 50g of the sodium loess, keeping the solid-liquid ratio at 1:5, acidifying at 90 ℃ for 15h, filtering and washing to be neutral, and drying at 120 ℃ to obtain the acidified loess.
And (3) wet alkalization, namely uniformly mixing 20g of acidified loess with 22g of sodium hydroxide solid, adding 47g of deionized water, reacting at 80 ℃ for 6 hours, and cooling to room temperature to obtain the wet alkalized loess.
Crystallization, 20g (solid content) of wet alkalized loess is taken, 26.78g of aluminum sulfate, 17.5g of sodium hydroxide and 191g of deionized water are added and stirred uniformly, and the raw material molar ratio in the slurry is ensured to be SiO 2 ∶Al 2 O 3 ∶H 2 Adding 4A molecular sieve seed crystal with the addition amount of 2% of the mass of the slurry, aging for 10h at room temperature, transferring into a high-pressure reaction kettle, placing in an oven, reacting for 4h at 90 ℃, washing with an acid solution, washing with deionized water until the pH =9, filtering, and drying at 90 ℃ to obtain the loess-based 4A molecular sieve, wherein the pH =13 is about O: naOH = 1.9: 1: 215: 13 and the pH = 13.
Detection shows that the specific surface area of the prepared loess-based 4A molecular sieve is 51.432m 2 The volume of the total hole is 0.02540cm 3 /g。
Example 3
Purifying: washing loess raw material with deionized water, filtering with 200 mesh sieve, repeating for 3-5 times, and oven drying at 120 deg.C for 2 hr. Obtaining purified loess;
sodium treatment, namely preparing a NaCl solution with the concentration of 30% by taking NaCl as a sodium treatment agent, adding 100.0g of purified loess to ensure that the solid-liquid ratio is 1:5, stirring for 5 hours at 90 ℃, filtering, washing and drying at 120 ℃ to obtain the sodium-treated loess;
acidifying, namely preparing dilute sulfuric acid with the mass concentration of 30%, adding 50g of the sodium loess, keeping the solid-liquid ratio at 1:5, acidifying at 90 ℃ for 15h, filtering and washing to be neutral, and drying at 120 ℃ to obtain the acidified loess.
And (3) wet alkalization, namely uniformly mixing 20g of acidified loess with 22g of sodium hydroxide solid, adding 47g of deionized water, reacting at 80 ℃ for 6 hours, and cooling to room temperature to obtain the wet alkalized loess.
Crystallization, 10g (solid content) of wet alkalized loess is taken, 13.39g of aluminum sulfate, 8.75g of sodium hydroxide and 101.1g of deionized water are added and stirred evenly to ensure that the raw material mol ratio in the slurry is SiO 2 ∶Al 2 O 3 ∶H 2 Adding 4A molecular sieve seed crystal with the addition amount of 2% of the mass of the slurry, aging for 9h at room temperature, transferring into a high-pressure reaction kettle, placing into an oven, reacting for 5h at 90 ℃, washing with an acid solution, washing with deionized water until the pH is =9, filtering, and drying at about 90 ℃ to obtain the loess-based 4A molecular sieve, wherein the ratio of O to NaOH is = 1.9: 1: 215: 13, and the pH is about = 13.
Detection shows that the specific surface area of the prepared loess-based 4A molecular sieve is 53.82m 2 The total pore volume is 0.027630cm 3 /g。
Example 4
Purifying: washing loess raw material with deionized water, filtering with 200 mesh sieve, repeating for 3-5 times, and oven drying at 120 deg.C for 2 hr. Obtaining purified loess;
sodium treatment, namely preparing a NaCl solution with the concentration of 40% by taking NaCl as a sodium agent, adding 100.0g of purified loess to ensure that the solid-liquid ratio is 1:5, stirring for 5 hours at 95 ℃, filtering, washing and drying at 120 ℃ to obtain the sodium-treated loess;
acidifying, namely preparing dilute sulfuric acid with the mass concentration of 40%, adding 100g of the sodium loess, keeping the solid-liquid ratio at 1:5, acidifying at 90 ℃ for 12h, filtering and washing to be neutral, and drying at 120 ℃ to obtain the acidified loess.
Dry alkalization, namely uniformly mixing 50g of acidified loess and 52g of sodium hydroxide solid, calcining for 3h at 450 ℃, and cooling to room temperature for later use.
Taking 50g of dry alkalized loess, adding 66.48g of aluminum sulfate, 43.75g of sodium hydroxide and 507.5g of deionized water, uniformly stirring to ensure that the raw material molar ratio in the slurry is SiO 2 ∶Al 2 O 3 ∶H 2 Adding 4A molecular sieve seed crystal with the addition amount of 2% of the mass of the slurry, aging for 10h at room temperature, transferring into a high-pressure reaction kettle, placing in an oven, reacting for 4h at 90 ℃, washing with an acid solution, washing with deionized water until the pH =9, filtering, and drying at 90 ℃ to obtain the loess-based 4A molecular sieve, wherein the pH =13 is about O: naOH = 1.9: 1: 215: 13 and the pH = 13.
Detection shows that the specific surface area of the prepared loess-based 4A molecular sieve is 58.45m 2 The total pore volume is 0.033160cm 3 /g。
Example 5
Purifying: washing loess raw material with deionized water, filtering with 200 mesh sieve, repeating for 3-5 times, and oven drying at 120 deg.C for 2 hr. Obtaining purified loess;
sodium treatment, namely preparing a NaCl solution with the concentration of 20% by taking NaCl as a sodium treatment agent, adding 100.0g of purified loess to ensure that the solid-liquid ratio is 1:3, stirring for 6 hours at 80 ℃, filtering, washing and drying at 120 ℃ to obtain the sodium-treated loess;
acidifying, preparing a dilute sulfuric acid solution with the mass concentration of 30%, adding 50g of the sodium loess, keeping the solid-liquid ratio at 1:5, acidifying at 90 ℃ for 15 hours, filtering, washing to be neutral, and drying at 120 ℃ to obtain the acidified loess.
Wet alkalization, namely taking 50g of acidified loess and 52g of sodium hydroxide solid, uniformly mixing, adding 110g of deionized water, reacting at 85 ℃ for 6 hours, and then cooling to room temperature to obtain the wet alkalized loess
Taking 50g (solid content) of wet alkalized loess, adding 66.48g of aluminum sulfate, 43.75g of sodium hydroxide and 401.1g of deionized water, uniformly stirring to ensure that the raw material molar ratio in the slurry is SiO 2 ∶Al 2 O 3 ∶H 2 Adding 4A molecular sieve seed crystal with the addition amount of 2% of the mass of the slurry into the slurry, aging the slurry for 12h at room temperature, transferring the slurry into a high-pressure reaction kettle, placing the slurry into an oven, reacting the slurry for 5h at 90 ℃, washing the slurry with an acid solution, washing the slurry with deionized water until the pH is about =9, filtering the slurry, and drying the slurry at about 90 ℃ to obtain the loess-based 4A molecular sieveAnd (4) screening.
Detection shows that the specific surface area of the prepared loess-based 4A molecular sieve is 55.62m 2 The volume of the total hole is 0.029860cm 3 /g。
The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. It is not intended to limit the invention to the precise form disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and its practical application to enable one skilled in the art to make and use various exemplary embodiments of the invention and various alternatives and modifications as are suited to the particular use contemplated.
Claims (10)
1. A preparation method of a loess-based 4A-type molecular sieve is characterized by comprising the following steps:
purifying: washing and drying loess in northwest region with water to obtain purified loess;
sodium treatment: mixing the sodium treatment agent solution and the purified loess uniformly, and performing sodium treatment reaction to obtain sodium-treated loess;
acidifying: adding an acid solution into the sodium loess, and carrying out an acidification reaction to obtain acidified loess;
alkalization: alkalizing the acidified loess to obtain alkalized loess, wherein the alkalization comprises any one of dry activation method or wet activation method;
and (3) crystallization: detecting the components of the alkalized loess, replenishing an aluminum source, an alkali source and water to ensure that the molar ratio of the raw materials in the slurry is SiO 2 ∶Al 2 O 3 ∶H 2 O: naOH = (1-2): 1: (210-230): 13-15); adding 4A molecular sieve seed crystal, aging at room temperature, transferring into a closed reaction kettle, and performing crystallization reaction to obtain the Huang Tuji A type molecular sieve.
2. The method for preparing a loess-based 4A-type molecular sieve according to claim 1, wherein in the purification step, the loess has a silica-alumina molar ratio of SiO 2 ∶Al 2 O 3 ＝(6.8～8.8)：1。
3. The method for preparing a loess-based 4A-type molecular sieve according to claim 1, wherein the preparation method of the sodifying agent solution in the sodium-treating step comprises: uniformly mixing a sodium reagent and deionized water to obtain an aqueous solution with the mass concentration of 20-60%; the sodium reagent is selected from NaCO 3 One or more of NaCl and NaF; the solid-liquid ratio of the purified loess to the sodium treatment agent solution is 1: (3-6), wherein the sodium treatment reaction conditions are as follows: reacting for 2-6 h at 70-100 ℃.
4. The method for preparing a loess-based 4A-type molecular sieve according to claim 1, wherein the acidic solution is sulfuric acid having a mass concentration of 20 to 50%; the solid-liquid ratio of the sodium loess to the acid solution is 1: (3-6); the acidification reaction conditions are as follows: stirring and reacting for 8-24 h at the temperature of 80-95 ℃.
5. The method for preparing a loess-based 4A-type molecular sieve according to claim 1, wherein the dry activation method comprises the steps of: uniformly mixing the acidified loess with alkali source solid powder, and calcining to obtain dry-method alkalized loess; the calcination temperature is 300-400 ℃, and the calcination time is 1-5 h.
6. The method for preparing a loess-based 4A-type molecular sieve according to claim 1, wherein the wet activation method comprises the steps of: uniformly mixing the alkali source solid with deionized water to obtain an alkali source solution with the mass concentration of 5-50%, adding acidified loess into the alkali source solution, and stirring at the temperature of 70-95 ℃ for 2-8 h to obtain the wet-process alkalized loess.
7. The method for preparing a loess-based 4A-type molecular sieve according to any one of claims 5 or 6, wherein the alkali-derived solid is one or more selected from the group consisting of NaOH, KOH and LiOH in the alkalization step, and the mass ratio of the acidified loess to the alkali-derived solid is 1: (0.5-2).
8. The method for preparing a loess-based 4A type molecular sieve as claimed in claim 1, wherein the aluminum source is one or more of aluminum sulfate and sodium metaaluminate; the alkali source is one or more of NaOH, KOH and LiOH; the addition amount of the 4A molecular sieve seed crystal is 2-5% of the mass of the slurry; the aging time is 6-12 h; the crystallization temperature is 90-100 ℃, and the crystallization time is 3-8 h.
9. The loess-based 4A type molecular sieve as set forth in any one of claims 1 to 8, wherein the Huang Tuji A type molecular sieve has a cage-like spherical structure and a specific surface area of 50 to 60m 2 The total pore volume is 0.0250-0.0350 cm 3 /g。
10. The use of the loess-based 4A-type molecular sieve according to any one of claims 1 to 8 or the loess-based 4A-type molecular sieve according to claim 9 in the fields of detergent industry, water treatment, fine chemical industry, environmental protection, petrochemical industry, and medicine.
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