CN112705255A - Method for preparing Cu-type microporous molecular sieve by Na-type microporous molecular sieve in one step, obtained product and application - Google Patents
Method for preparing Cu-type microporous molecular sieve by Na-type microporous molecular sieve in one step, obtained product and application Download PDFInfo
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- 239000002808 molecular sieve Substances 0.000 title claims abstract description 117
- 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 113
- 238000000034 method Methods 0.000 title claims abstract description 52
- 150000001879 copper Chemical class 0.000 claims abstract description 23
- 229910052710 silicon Inorganic materials 0.000 claims description 18
- 239000010703 silicon Substances 0.000 claims description 18
- 238000003756 stirring Methods 0.000 claims description 16
- 238000005342 ion exchange Methods 0.000 claims description 14
- 238000006243 chemical reaction Methods 0.000 claims description 13
- 238000010438 heat treatment Methods 0.000 claims description 13
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 9
- 239000012266 salt solution Substances 0.000 claims description 9
- 239000003054 catalyst Substances 0.000 claims description 8
- 238000002156 mixing Methods 0.000 claims description 5
- ORTQZVOHEJQUHG-UHFFFAOYSA-L copper(II) chloride Chemical group Cl[Cu]Cl ORTQZVOHEJQUHG-UHFFFAOYSA-L 0.000 claims description 2
- OPQARKPSCNTWTJ-UHFFFAOYSA-L copper(ii) acetate Chemical compound [Cu+2].CC([O-])=O.CC([O-])=O OPQARKPSCNTWTJ-UHFFFAOYSA-L 0.000 claims description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims 1
- 229910052782 aluminium Inorganic materials 0.000 claims 1
- 238000004519 manufacturing process Methods 0.000 claims 1
- 239000010949 copper Substances 0.000 abstract description 16
- 229910052802 copper Inorganic materials 0.000 abstract description 8
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 abstract description 7
- 239000002351 wastewater Substances 0.000 abstract description 6
- 150000003863 ammonium salts Chemical class 0.000 abstract description 5
- QGZKDVFQNNGYKY-UHFFFAOYSA-O ammonium group Chemical group [NH4+] QGZKDVFQNNGYKY-UHFFFAOYSA-O 0.000 abstract description 2
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 26
- 239000000243 solution Substances 0.000 description 18
- 230000000052 comparative effect Effects 0.000 description 15
- 238000001035 drying Methods 0.000 description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 11
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 10
- 239000011259 mixed solution Substances 0.000 description 9
- 239000000203 mixture Substances 0.000 description 9
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 9
- 238000005303 weighing Methods 0.000 description 9
- 238000002360 preparation method Methods 0.000 description 7
- 229910021592 Copper(II) chloride Inorganic materials 0.000 description 5
- CSDREXVUYHZDNP-UHFFFAOYSA-N alumanylidynesilicon Chemical compound [Al].[Si] CSDREXVUYHZDNP-UHFFFAOYSA-N 0.000 description 5
- 239000007789 gas Substances 0.000 description 5
- 230000007935 neutral effect Effects 0.000 description 5
- 239000000377 silicon dioxide Substances 0.000 description 5
- 238000005406 washing Methods 0.000 description 5
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 4
- 229910002651 NO3 Inorganic materials 0.000 description 4
- XKMRRTOUMJRJIA-UHFFFAOYSA-N ammonia nh3 Chemical compound N.N XKMRRTOUMJRJIA-UHFFFAOYSA-N 0.000 description 4
- 230000003197 catalytic effect Effects 0.000 description 4
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 3
- 229910021591 Copper(I) chloride Inorganic materials 0.000 description 3
- -1 NH4NO3 Chemical compound 0.000 description 3
- 238000001354 calcination Methods 0.000 description 3
- OXBLHERUFWYNTN-UHFFFAOYSA-M copper(I) chloride Chemical compound [Cu]Cl OXBLHERUFWYNTN-UHFFFAOYSA-M 0.000 description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 2
- 230000001276 controlling effect Effects 0.000 description 2
- SXTLQDJHRPXDSB-UHFFFAOYSA-N copper;dinitrate;trihydrate Chemical compound O.O.O.[Cu+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O SXTLQDJHRPXDSB-UHFFFAOYSA-N 0.000 description 2
- 239000008367 deionised water Substances 0.000 description 2
- 229910021641 deionized water Inorganic materials 0.000 description 2
- 238000009616 inductively coupled plasma Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000000779 smoke Substances 0.000 description 2
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 1
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 238000003916 acid precipitation Methods 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 239000007864 aqueous solution Substances 0.000 description 1
- 238000010531 catalytic reduction reaction Methods 0.000 description 1
- 238000005119 centrifugation Methods 0.000 description 1
- XTVVROIMIGLXTD-UHFFFAOYSA-N copper(II) nitrate Chemical compound [Cu+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O XTVVROIMIGLXTD-UHFFFAOYSA-N 0.000 description 1
- 229910000366 copper(II) sulfate Inorganic materials 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000001627 detrimental effect Effects 0.000 description 1
- 239000003814 drug Substances 0.000 description 1
- 229940079593 drug Drugs 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000004993 emission spectroscopy Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 238000002715 modification method Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000012795 verification Methods 0.000 description 1
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J29/00—Catalysts comprising molecular sieves
- B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
- B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
- B01J29/70—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65
- B01J29/72—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65 containing iron group metals, noble metals or copper
- B01J29/76—Iron group metals or copper
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/8621—Removing nitrogen compounds
- B01D53/8625—Nitrogen oxides
- B01D53/8628—Processes characterised by a specific catalyst
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/74—General processes for purification of waste gases; Apparatus or devices specially adapted therefor
- B01D53/86—Catalytic processes
- B01D53/8621—Removing nitrogen compounds
- B01D53/8634—Ammonia
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/08—Heat treatment
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/30—Ion-exchange
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2257/00—Components to be removed
- B01D2257/40—Nitrogen compounds
- B01D2257/404—Nitrogen oxides other than dinitrogen oxide
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2257/00—Components to be removed
- B01D2257/40—Nitrogen compounds
- B01D2257/406—Ammonia
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Abstract
The invention discloses a method for preparing a Cu-type microporous molecular sieve by a Na-type microporous molecular sieve in one step, an obtained product and application. The invention obtains a Cu-type micropore molecular sieve suitable for preparing various Na-type micropore molecular sieves by changing the types of copper salts and controlling the concentration of the copper saltsMolecular sieve, and can change the Cu content of the Cu-type microporous molecular sieve by controlling the concentration of copper salt. Compared with the prior art, the method avoids the use of ammonium salt in the ammonium exchange process, has simpler working procedure, obviously reduces the cost and reduces the generation of waste water, and compared with the traditional Cu-type microporous molecular sieve, the Cu-type microporous molecular sieve product prepared by the method has NH3SCR performance is comparable.
Description
Technical Field
The invention relates to a method for preparing a Cu-type microporous molecular sieve by a Na-type microporous molecular sieve in one step, a Cu-type microporous molecular sieve prepared by the method and application of NH3Application on SCR, belonging to the technical field of molecular sieve preparation.
Background
Nitrogen Oxides (NO) in motor vehicle exhaust gases x ) Is one of the main atmospheric pollutants, and can cause atmospheric environmental problems such as acid rain, photochemical smog, dust haze and the like. The current ammonia selective catalytic reduction technology (NH)3SCR) is the main diesel vehicle exhaust NO x The method comprises the following steps of removing a catalyst, wherein the catalyst is the core of the technology, and the Cu-type microporous molecular sieve (Cu-SSZ-13) becomes a standard catalyst meeting the national VI emission standard of diesel vehicles by virtue of excellent catalytic performance and hydrothermal stability. The traditional preparation method of the catalyst is generally obtained by a series of ion exchange of Na-type microporous molecular sieve, namely NH4NO3、NH4Cl or NH4SO4Carrying out 2-3 NH times on the Na-type microporous molecular sieve by using an ammonium salt aqueous solution4 +And exchanging, and then exchanging by copper salt to obtain the Cu-type microporous molecular sieve. In the preparation process of the method, a large amount of ammonia nitrogen wastewater is generated by using all ammonium salts, wherein NH4NO3And the Cu-type microporous molecular sieve is also an easily explosive drug and is strictly controlled, for example, the Cu-type microporous molecular sieve is obtained by adopting the traditional ion exchange method in the patent CN110078090A, the process is complex, unsafe factors exist, and the cost is high. Patent CN109881531A discloses a preparation method of a copper modified sodium type 4A molecular sieve smoke suppressant, which comprises the steps of dissolving a molecular sieve in deionized water, adding copper nitrate trihydrate, heating, stirring, filtering, drying and roasting to obtain the copper type 4A molecular sieve. The molecular sieve obtained by the method is mainlyThe method has the function of smoke suppression, the copper modification effect of the method on microporous molecular sieves such as Na-type SSZ-13, Na-type SSZ-39 and high-silicon LTA is poor, and NH of the obtained modified molecular sieve3The SCR performance is poor.
It can be seen that NH of the product obtained by one-step ion exchange of Na-SSZ-13, Na-SSZ-39 and high-silicon LTA molecular sieves by the method disclosed in patent CN109881531A3The SCR performance is not ideal, and a large amount of ammonia nitrogen wastewater is generated in the exchange process. Further research is needed to perform copper modification on the molecular sieves to obtain a modification method with good performance and simple preparation.
Disclosure of Invention
Aiming at the defects in the prior art, the invention provides a method for preparing a Cu-type microporous molecular sieve by a Na-type microporous molecular sieve in one step and an obtained product, the method has simple process and simple and convenient operation, does not generate a large amount of ammonia nitrogen wastewater, and the obtained Cu-type microporous molecular sieve has NH (NH) compared with the Cu-type microporous molecular sieve prepared by the traditional method3SCR performance is comparable.
The specific technical scheme of the invention is as follows:
a method for preparing a Cu-type microporous molecular sieve by a Na-type microporous molecular sieve in one step comprises the following steps: directly mixing the copper salt solution with the Na-type microporous molecular sieve, adjusting the pH value to acidity, heating and stirring for ion exchange, collecting a product after reaction, and roasting to obtain the Cu-type microporous molecular sieve.
Further, the copper salt is copper chloride or copper acetate. The copper salt is selected from the types, and compared with copper nitrate, the copper salt avoids the generation of ammonia nitrogen wastewater.
Further, the concentration of the copper salt solution is 0.002 to 0.05 mol/L, preferably 0.02 mol/L. Concentration of copper salt to NH of the finally obtained molecular sieve3SCR performance impacts, too high a concentration being detrimental to NH3SCR, therefore the concentration is chosen by the invention. In this concentration range, NH of the resulting product3-SCR performance comparable to conventional Cu-type microporous molecular sieves.
Further, the Na-type microporous molecular sieve is a Na-SSZ-13 molecular sieve, a Na-SSZ-39 molecular sieve or a high-silicon Na-LTA molecular sieve. Wherein, the Si/Al ratio of the Na-SSZ-13 molecular sieve is 4-25, the Si/Al ratio of the Na-SSZ-39 molecular sieve is 6-30, the Si/Al ratio of the high-silicon Na-LTA molecular sieve is 2-23, and the Si/Al ratio is the molar ratio of Si to Al in the molecular sieve.
Further, the Na-type microporous molecular sieve is mixed with excessive copper salt solution, so that the molecular sieve can be completely immersed in the solution.
Further, after directly mixing the copper salt solution with the Na-type microporous molecular sieve, adjusting the pH value to 3-4. The pH can be adjusted by a commonly used acid or base, for example, hydrochloric acid, aqueous ammonia, etc.
Further, heating to 80-90 deg.C for ion exchange. The time for ion exchange is 1-3 h, preferably 2 h.
Further, after ion exchange, products are collected through centrifugation, then washed to be neutral, dried and roasted to obtain the Cu-type microporous molecular sieve. The drying temperature is generally 80-105 ℃, and the calcination temperature is generally 550-600 ℃. The calcination is carried out in an air atmosphere, the calcination time generally being 6 to 10 hours.
The Cu-type microporous molecular sieve obtained by the method has better NH proved by verification3SCR properties, so that the Cu-type microporous molecular sieve and the molecular sieve act as NH3The use of SCR catalysts is also within the scope of protection.
The invention has the following advantages:
1. and first 2-3 NH passes4 +Ion exchange followed by Cu2+Compared with the traditional method of ion exchange, the one-step ion exchange method adopted by the invention saves the steps of multiple times of ammonium salt exchange, avoids the use of ammonium salt in the ammonium exchange process, has simpler working procedures, obviously reduces the cost and reduces the generation of waste water.
2. The method for preparing the copper microporous molecular sieve in one step, which is suitable for various Na microporous molecular sieves, is obtained by changing the types of the copper salts and controlling the concentration of the copper salts, and the Cu content of the Cu microporous molecular sieve can be changed by controlling the concentration of the copper saltsDenitration NH of diesel vehicle exhaust3-SCR field, NH in comparison with conventional Cu type microporous molecular sieves3SCR performance is comparable.
Detailed Description
In order to make the technical solutions of the present application more clearly understood by those skilled in the art, the technical solutions of the present application will be described in detail below with reference to specific embodiments. It should be noted that the following detailed description is exemplary and is intended to provide further explanation of the disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.
Example 1
Weighing 1 g of Na-SSZ-13 molecular sieve with the silicon-aluminum ratio of 4 into a three-neck flask, and weighing 50 mL of CuCl with the concentration of 0.01 mol/L2Solution of CuCl2The solution was mixed with Na-SSZ-13 molecular sieves with stirring and the pH was adjusted between 3 and 4 at 30 ℃ with 0.1 mol/L HCl. After the pH of the mixed solution is stable, transferring the three-neck flask filled with the mixed solution into a water bath kettle with water at 80 ℃, and heating and stirring for 1 h. And (3) centrifugally washing the mixture to be neutral, pre-drying the mixture at 80 ℃ for 8 h, then drying the mixture at 105 ℃ for 12 h, and finally roasting the mixture at 575 ℃ in an air atmosphere for 8 h to obtain the Cu-SSZ-13 molecular sieve.
Example 2
A Cu-SSZ-13 molecular sieve was prepared according to the method of example 1, except that the copper salt solution was changed to 0.02 mol/L CuCl2A solution; heating in water bath at 80 deg.C for 2 hr.
Example 3
A Cu-SSZ-13 molecular sieve was prepared in accordance with the procedure of example 1, except that the Na-SSZ-13 molecular sieve used had a silica to alumina ratio of 10; the copper salt solution was changed to 0.05 mol/L Cu (CH)3COO)2A solution; the heating and stirring time is 3 h.
Example 4
A Cu-SSZ-13 molecular sieve was prepared according to the method of example 1. In contrast, the Na-SSZ-13 molecular sieve used has a silica to alumina ratio of 25; the copper salt solution is 0.002 mol/L CuCl2And (3) solution.
Example 5
Weighing 1 g of Na-SSZ-39 molecular sieve with the silicon-aluminum ratio of 6 into a three-neck flask, and weighing 50 mL of CuCl with the concentration of 0.05 mol/L2Solution of CuCl2The solution was mixed with Na-SSZ-39 molecular sieves with stirring and 20 wt.% NH at 30 deg.C3·H2And O, adjusting the pH value to 3-4. After the pH of the mixed solution is stable, transferring the three-neck flask filled with the mixed solution into a water bath kettle at the temperature of 80 ℃, and heating and stirring for 2 hours. And centrifuging the mixture, washing to be neutral, pre-drying at 80 ℃ for 8 h, then drying at 105 ℃ for 12 h, and finally roasting at 575 ℃ in air atmosphere for 8 h to obtain the Cu-SSZ-39 molecular sieve.
Example 6
A Cu-SSZ-39 molecular sieve was prepared according to the method of example 5, except that the Na-SSZ-39 molecular sieve used had a silica to alumina ratio of 30; heating in water bath at 80 deg.C and stirring for 3 hr.
Example 7
Weighing 1 g of high-silicon Na-LTA molecular sieve with the silicon-aluminum ratio of 15 in a three-neck flask, and weighing 50 mL of CuCl with the concentration of 0.01 mol/L2Solution of CuCl2The solution is mixed with a high-silicon Na-LTA molecular sieve and stirred, and the pH is adjusted to 3-4 by 0.1 mol/L HCl at the temperature of 30 ℃. After the pH of the mixed solution is stable, transferring the three-neck flask filled with the mixed solution into a water bath kettle at 90 ℃, and heating and stirring for 1 h. And centrifuging the mixture, washing to be neutral, pre-drying at 80 ℃ for 8 h, then drying at 105 ℃ for 12 h, and finally roasting at 575 ℃ in air atmosphere for 8 h to obtain the high-silicon Cu-LTA molecular sieve.
Example 8
A high silicon type Cu-LTA molecular sieve was prepared according to the procedure of example 7 except that the high silicon type Na-LTA molecular sieve was used with a silica to alumina ratio of 23.
Example 9
A high-silicon type Cu-LTA molecular sieve was prepared by following the procedure of example 7 except that the high-silicon type Na-LTA molecular sieve was used with a Si/Al ratio of 2 and heated in a water bath at 90 ℃ with stirring for 1 hour.
Comparative example 1
Weighing 10 g of Na-SSZ-13 molecular sieve with the silicon-aluminum ratio of 4 into a three-neck flask, adding 100 mL of deionized water, ultrasonically dispersing until the mixture is uniform, adding 2 g of solid copper nitrate trihydrate into the solution, adjusting the pH value of the solution to be 4 by using nitric acid, and stirring for 2 hours at 90 ℃. Centrifuging, drying and roasting to obtain the Cu-SSZ-13 molecular sieve.
Comparative example 2
Weighing 1 g of Na-SSZ-13 molecular sieve with the silicon-aluminum ratio of 4 in a three-neck flask, and measuring 50 mL of NH with the concentration of 1 mol/L4NO3Solution of NH4NO3Mixing the solution with Na-SSZ-13 molecular sieve, stirring, and adding 20 wt.% NH at 30 deg.C3·H2And O, adjusting the pH value to 3-4. After the pH of the mixed solution is stable, transferring the three-neck flask filled with the mixed solution into a water bath kettle at the temperature of 80 ℃, and heating and stirring for 2 hours. Centrifuging the mixture, washing to neutrality, drying, repeating the step for 2 times to obtain NH4-SSZ-13. Weighing 1 g of NH4The SSZ-13 molecular sieve is put in a three-neck flask, and 40 mL of CuSO with the concentration of 0.1 mol/L is measured4Solution of CuSO4Solution with NH4Mixing and stirring the-SSZ-13 molecular sieve, transferring the three-neck flask filled with the mixed solution into a water bath kettle at the temperature of 80 ℃, and heating and stirring for 1 hour. And centrifuging the mixture, washing to be neutral, pre-drying at 80 ℃ for 8 h, then drying at 105 ℃ for 12 h, and roasting at 575 ℃ for 8 h to obtain the Cu-SSZ-13 molecular sieve.
Comparative example 3
A Cu-SSZ-39 molecular sieve was synthesized according to the method of comparative example 2, except that Na-SSZ-39 was used as the molecular sieve and the silica to alumina ratio was 6.
Comparative example 4
A high-silicon type Cu-LTA molecular sieve was synthesized according to the method of comparative example 2, except that the molecular sieve used was a high-silicon type Na-LTA molecular sieve having a Si/Al ratio of 15.
Application example
1. The Cu content of the Cu-type microporous molecular sieves prepared in the above examples and comparative examples with different copper salt concentrations was measured by inductively coupled plasma emission spectroscopy (ICP), and the results are shown in table 1:
as can be seen from examples 1-3, the Cu content of the Cu-SSZ-13 molecular sieve prepared by different concentrations of copper salt is different, and the Cu content is higher and higher with the increase of the concentration of the copper salt. The content of copper in the finally obtained molecular sieve can be regulated and controlled by adjusting the concentration of copper salt.
2. NH of the Cu-type microporous molecular sieves prepared in the above examples and comparative examples3-SCR catalytic performance evaluation. The method comprises the following steps:
2.1. the experimental steps are as follows:
the molecular sieves of examples 1-4, 5, 7 and comparative examples 1-4 were used as NH3SCR catalyst, loading the sieved catalyst (40-60 mesh) into a reaction tube, and introducing O2、NO、NH3And He four standard reaction gases are introduced into the reaction tube, wherein the concentration of the standard gases is 500 ppm of NO and 500 ppm of NH35.3 vol.% O2He is used as balance gas, the flow rate is 300 mL/min, and the space velocity is 100000 h-1. The bottom end of the reaction tube adopts a temperature controller to control the temperature of the reaction tube in real time, and the outlet of the reaction tube utilizes a mass spectrometer to monitor N2O、NH3Concentration of (3), NO x Analyzer for monitoring NO and NO2、NO x The concentration of (c). Setting the temperature interval as 100-600 deg.C, testing one temperature point every 25-50 deg.C, recording NO and NO when the gas concentration detected at each temperature point reaches a stable value2、NO x 、N2O、NH3Calculating NO of x Conversion and N2Selectivity, investigating NH3-SCR catalytic performance.
The catalytic activity of the Cu-type microporous molecular sieve was evaluated:
the Cu-type microporous molecular sieves in the examples and comparative examples were performed according to the method of step 1.
2.2.1. Table 2 below shows NH of Cu-SSZ-13 in comparative example 1 and comparative example 23SCR Performance, as can be seen from the table, the Cu-SSZ-13 molecular sieve obtained with reference to the process of the previously reported patent has NO in comparison with Cu-SSZ-13 prepared by the conventional process x The conversion rate is poor, and the temperature window is narrow. It can be seen that the method in CN109881531A is not suitable for preparing Cu-SSZ-13 molecular sieve.
2.2.2. Tables 3 and 4 show NH of Cu-SSZ-13 in examples 1 to 4 and comparative example 23SCR performance, as can be seen from the table, whether NO x Conversion is also N2Selectively, the Cu-SSZ-13 obtained by the ion exchange method has the performance equivalent to that of the Cu-SSZ-13 prepared by the traditional method.
2.2.3. Table 5 shows NH of Cu-SSZ-39 in example 5 and comparative example 33SCR performance, as can be seen from the table, whether NO x Conversion is also N2Selectively, the Cu-SSZ-39 prepared by the two preparation methods has equivalent performance.
2.2.4. Table 6 shows NH of high-silicon type Cu-LTA in example 7 and comparative example 43SCR performance, as can be seen from the table, whether NO x Conversion is also N2And the selectivity is equal to that of the high-silicon type Cu-LTA prepared by the two preparation methods.
In conclusion, the Cu-type microporous molecular sieve prepared by the invention has better NH3SCR performance, NH compared to conventional Cu-type microporous molecular sieves3SCR performance is comparable.
Claims (10)
1. A method for preparing a Cu-type microporous molecular sieve by a Na-type microporous molecular sieve in one step is characterized by comprising the following steps: directly mixing the copper salt solution with the Na-type microporous molecular sieve, adjusting the pH value to acidity, heating and stirring, carrying out ion exchange, collecting a product after reaction, and roasting to obtain the Cu-type microporous molecular sieve.
2. The method of claim 1, further comprising: the copper salt is copper chloride or copper acetate.
3. A method according to claim 1 or 2, characterized by: the concentration of the copper salt solution is 0.002-0.05 mol/L, preferably 0.02 mol/L.
4. The method of claim 1, further comprising: the Na-type microporous molecular sieve is a Na-SSZ-13 molecular sieve, a Na-SSZ-39 molecular sieve or a high-silicon Na-LTA molecular sieve.
5. The method of claim 4, wherein: the silica-alumina ratio of the Na-SSZ-13 molecular sieve is 4-25, the silica-alumina ratio of the Na-SSZ-39 molecular sieve is 6-30, the silica-alumina ratio of the high-silicon Na-LTA molecular sieve is 2-23, and the silica-alumina ratio is the mole ratio of silicon and aluminum in the molecular sieve.
6. The method of claim 1, further comprising: adjusting pH to 3-4.
7. The method of claim 1, further comprising: heating to 80-90 deg.C for ion exchange.
8. The method of claim 1 or 7, wherein: the time for ion exchange is 1-3 h, preferably 2 h.
9. The Cu-type microporous molecular sieve prepared by the one-step process for preparing a Cu-type microporous molecular sieve according to the Na-type microporous molecular sieve of any one of claims 1 to 8.
10. In the application ofThe Cu-type microporous molecular sieve of claim 9 is used as NH3-use of an SCR catalyst.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116493040A (en) * | 2023-04-26 | 2023-07-28 | 济南大学 | Preparation method of high-performance Cu-based small-pore molecular sieve catalyst, obtained product and application |
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| LU55048A1 (en) * | 1966-12-09 | 1968-02-27 | ||
| CN102946997A (en) * | 2009-12-18 | 2013-02-27 | 巴斯夫公司 | Process of direct copper exchange into na+-form of chabazite molecular sieve, and catalysts, systems and methods |
| CN111408401A (en) * | 2020-04-02 | 2020-07-14 | 济南大学 | Preparation method of Cu-SSZ-13 with wide temperature window, obtained product and application |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| LU55048A1 (en) * | 1966-12-09 | 1968-02-27 | ||
| CN102946997A (en) * | 2009-12-18 | 2013-02-27 | 巴斯夫公司 | Process of direct copper exchange into na+-form of chabazite molecular sieve, and catalysts, systems and methods |
| CN111408401A (en) * | 2020-04-02 | 2020-07-14 | 济南大学 | Preparation method of Cu-SSZ-13 with wide temperature window, obtained product and application |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116493040A (en) * | 2023-04-26 | 2023-07-28 | 济南大学 | Preparation method of high-performance Cu-based small-pore molecular sieve catalyst, obtained product and application |
| CN116493040B (en) * | 2023-04-26 | 2024-05-07 | 济南大学 | Preparation method of high-performance Cu-based small-pore molecular sieve catalyst, obtained product and application |
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