CN116586105A - Metal limited catalyst and preparation method and application thereof - Google Patents
Metal limited catalyst and preparation method and application thereof Download PDFInfo
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- CN116586105A CN116586105A CN202310556914.5A CN202310556914A CN116586105A CN 116586105 A CN116586105 A CN 116586105A CN 202310556914 A CN202310556914 A CN 202310556914A CN 116586105 A CN116586105 A CN 116586105A
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- 229910052751 metal Inorganic materials 0.000 title claims abstract description 78
- 239000002184 metal Substances 0.000 title claims abstract description 78
- 239000003054 catalyst Substances 0.000 title claims abstract description 64
- 238000002360 preparation method Methods 0.000 title abstract description 6
- 229910021536 Zeolite Inorganic materials 0.000 claims abstract description 28
- 239000010457 zeolite Substances 0.000 claims abstract description 28
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 claims abstract description 26
- 238000005216 hydrothermal crystallization Methods 0.000 claims abstract description 11
- 238000000746 purification Methods 0.000 claims abstract description 5
- 239000000243 solution Substances 0.000 claims description 27
- 239000010936 titanium Substances 0.000 claims description 16
- 229910052719 titanium Inorganic materials 0.000 claims description 16
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims description 15
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 claims description 12
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 12
- 239000012690 zeolite precursor Substances 0.000 claims description 12
- 238000000034 method Methods 0.000 claims description 10
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 9
- 229910052760 oxygen Inorganic materials 0.000 claims description 9
- 229910052710 silicon Inorganic materials 0.000 claims description 9
- 239000010703 silicon Substances 0.000 claims description 9
- 238000005406 washing Methods 0.000 claims description 8
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 7
- 229910052783 alkali metal Inorganic materials 0.000 claims description 7
- -1 alkali metal salt Chemical class 0.000 claims description 7
- 239000007864 aqueous solution Substances 0.000 claims description 7
- 238000001914 filtration Methods 0.000 claims description 7
- 239000007788 liquid Substances 0.000 claims description 7
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 6
- 238000001354 calcination Methods 0.000 claims description 6
- DCKVFVYPWDKYDN-UHFFFAOYSA-L oxygen(2-);titanium(4+);sulfate Chemical compound [O-2].[Ti+4].[O-]S([O-])(=O)=O DCKVFVYPWDKYDN-UHFFFAOYSA-L 0.000 claims description 6
- BWHMMNNQKKPAPP-UHFFFAOYSA-L potassium carbonate Chemical compound [K+].[K+].[O-]C([O-])=O BWHMMNNQKKPAPP-UHFFFAOYSA-L 0.000 claims description 6
- 239000001103 potassium chloride Substances 0.000 claims description 6
- 235000011164 potassium chloride Nutrition 0.000 claims description 6
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 claims description 6
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 6
- 229910000348 titanium sulfate Inorganic materials 0.000 claims description 6
- 238000001035 drying Methods 0.000 claims description 5
- 229910052782 aluminium Inorganic materials 0.000 claims description 4
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 4
- 239000003795 chemical substances by application Substances 0.000 claims description 4
- 230000007547 defect Effects 0.000 claims description 4
- 239000001301 oxygen Substances 0.000 claims description 4
- 238000011282 treatment Methods 0.000 claims description 4
- 239000004115 Sodium Silicate Substances 0.000 claims description 3
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 3
- 229910052697 platinum Inorganic materials 0.000 claims description 3
- 229910000027 potassium carbonate Inorganic materials 0.000 claims description 3
- 239000011780 sodium chloride Substances 0.000 claims description 3
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 3
- 229910052911 sodium silicate Inorganic materials 0.000 claims description 3
- XJDNKRIXUMDJCW-UHFFFAOYSA-J titanium tetrachloride Chemical compound Cl[Ti](Cl)(Cl)Cl XJDNKRIXUMDJCW-UHFFFAOYSA-J 0.000 claims description 3
- 230000003197 catalytic effect Effects 0.000 abstract description 5
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 14
- 239000007789 gas Substances 0.000 description 14
- 238000006243 chemical reaction Methods 0.000 description 11
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 10
- 230000000052 comparative effect Effects 0.000 description 9
- LPSKDVINWQNWFE-UHFFFAOYSA-M tetrapropylazanium;hydroxide Chemical group [OH-].CCC[N+](CCC)(CCC)CCC LPSKDVINWQNWFE-UHFFFAOYSA-M 0.000 description 8
- 239000011259 mixed solution Substances 0.000 description 7
- 239000011148 porous material Substances 0.000 description 6
- 238000012360 testing method Methods 0.000 description 6
- 229910002091 carbon monoxide Inorganic materials 0.000 description 4
- 230000001590 oxidative effect Effects 0.000 description 4
- 239000000047 product Substances 0.000 description 4
- 239000010453 quartz Substances 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 230000010718 Oxidation Activity Effects 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 238000005119 centrifugation Methods 0.000 description 3
- 230000007613 environmental effect Effects 0.000 description 3
- 238000000192 extended X-ray absorption fine structure spectroscopy Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 239000002105 nanoparticle Substances 0.000 description 3
- 229910000510 noble metal Inorganic materials 0.000 description 3
- 239000002243 precursor Substances 0.000 description 3
- 238000001228 spectrum Methods 0.000 description 3
- 238000003756 stirring Methods 0.000 description 3
- 238000001308 synthesis method Methods 0.000 description 3
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 2
- 238000004998 X ray absorption near edge structure spectroscopy Methods 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 2
- 238000006555 catalytic reaction Methods 0.000 description 2
- 239000008367 deionised water Substances 0.000 description 2
- 229910021641 deionized water Inorganic materials 0.000 description 2
- 239000011888 foil Substances 0.000 description 2
- 229930195733 hydrocarbon Natural products 0.000 description 2
- 150000002430 hydrocarbons Chemical class 0.000 description 2
- 230000003993 interaction Effects 0.000 description 2
- 239000002159 nanocrystal Substances 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 229910052717 sulfur Inorganic materials 0.000 description 2
- 239000011593 sulfur Substances 0.000 description 2
- 229940073455 tetraethylammonium hydroxide Drugs 0.000 description 2
- LRGJRHZIDJQFCL-UHFFFAOYSA-M tetraethylazanium;hydroxide Chemical compound [OH-].CC[N+](CC)(CC)CC LRGJRHZIDJQFCL-UHFFFAOYSA-M 0.000 description 2
- YLZOPXRUQYQQID-UHFFFAOYSA-N 3-(2,4,6,7-tetrahydrotriazolo[4,5-c]pyridin-5-yl)-1-[4-[2-[[3-(trifluoromethoxy)phenyl]methylamino]pyrimidin-5-yl]piperazin-1-yl]propan-1-one Chemical compound N1N=NC=2CN(CCC=21)CCC(=O)N1CCN(CC1)C=1C=NC(=NC=1)NCC1=CC(=CC=C1)OC(F)(F)F YLZOPXRUQYQQID-UHFFFAOYSA-N 0.000 description 1
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 1
- 229910021591 Copper(I) chloride Inorganic materials 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 230000004075 alteration Effects 0.000 description 1
- 229910001579 aluminosilicate mineral Inorganic materials 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- OXBLHERUFWYNTN-UHFFFAOYSA-M copper(I) chloride Chemical compound [Cu]Cl OXBLHERUFWYNTN-UHFFFAOYSA-M 0.000 description 1
- 229940045803 cuprous chloride Drugs 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 230000009849 deactivation Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 229960002089 ferrous chloride Drugs 0.000 description 1
- 230000005669 field effect Effects 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- NMCUIPGRVMDVDB-UHFFFAOYSA-L iron dichloride Chemical compound Cl[Fe]Cl NMCUIPGRVMDVDB-UHFFFAOYSA-L 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000002082 metal nanoparticle Substances 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 235000010755 mineral Nutrition 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000002253 near-edge X-ray absorption fine structure spectrum Methods 0.000 description 1
- GPNDARIEYHPYAY-UHFFFAOYSA-N palladium(ii) nitrate Chemical compound [Pd+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O GPNDARIEYHPYAY-UHFFFAOYSA-N 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 239000012429 reaction media Substances 0.000 description 1
- 230000003252 repetitive effect Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 239000004071 soot Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
Classifications
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- 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
- B01D53/92—Chemical or biological purification of waste gases of engine exhaust gases
- B01D53/94—Chemical or biological purification of waste gases of engine exhaust gases by catalytic processes
- B01D53/944—Simultaneously removing carbon monoxide, hydrocarbons or carbon making use of oxidation catalysts
-
- 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
- B01J29/89—Silicates, aluminosilicates or borosilicates of titanium, zirconium or hafnium
-
- 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
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
- B01J35/391—Physical properties of the active metal ingredient
-
- 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
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
- B01J35/396—Distribution of the active metal ingredient
-
- 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
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
- B01J35/64—Pore diameter
- B01J35/647—2-50 nm
-
- 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
- B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
- B01J2229/10—After treatment, characterised by the effect to be obtained
- B01J2229/18—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
- Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Materials Engineering (AREA)
- Health & Medical Sciences (AREA)
- Analytical Chemistry (AREA)
- General Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Environmental & Geological Engineering (AREA)
- Biomedical Technology (AREA)
- Combustion & Propulsion (AREA)
- Catalysts (AREA)
Abstract
The invention provides a metal finite field catalyst, a preparation method and application thereof, wherein metal is wrapped in zeolite in a metal atom or metal nano cluster form, and the metal finite field catalyst is obtained through hydrothermal pretreatment and hydrothermal crystallization and is applied to automobile tail gas purification. The technical scheme of the invention is simple and convenient to prepare, and the metal limited-area catalyst has higher stability and unique catalytic activity and shows unique advantages in the purification of automobile tail gas.
Description
Technical Field
The invention relates to the technical field of environmental catalysis, in particular to a zeolite-based metal finite field catalyst, a preparation method and application thereof.
Background
Diesel engines have received much attention for their high fuel efficiency, but they also emit large amounts of exhaust gases such as CO, hydrocarbons (HCs), soot particles, etc., causing a series of environmental problems. Therefore, it is urgent to design a highly efficient catalyst to eliminate such contamination.
Metal-based catalysts, particularly noble metals, have been rapidly developed in automobile exhaust treatment due to their unique physical and chemical properties, but their use has been greatly limited by the high cost.
Typically, noble metal nanoparticles are highly dispersed on metal oxides or porous supports to reduce cost and improve atomic utilization, such as Pt-loaded Al 2 O 3 Etc.
However, these metal catalysts are susceptible to deactivation at high temperatures due to sintering and agglomeration of the metals.
Disclosure of Invention
Aiming at the problems in the prior art, the invention aims to provide a metal limited-area catalyst capable of improving the stability of the catalyst, and a preparation method and application thereof.
According to an aspect of the present invention there is provided a metal-bound catalyst comprising a zeolite having mesoporous channels and a metal encapsulated within the zeolite in the form of metal atoms or metal nanoclusters.
Preferably: the metal is one or more of Pt, cu, bi, fe.
Preferably: the mass of the metal is 0.1-2 wt% of the total mass of the metal limiting catalyst.
Preferably: the metal-limited catalyst has oxygen vacancy defects.
According to another aspect of the present invention, there is provided a method for preparing the metal-limited catalyst described above, comprising the steps of:
step 1, dissolving an inorganic silicon source, a titanium source/aluminum source, carbonate and alkali metal salt in an aqueous solution containing a structure directing agent for hydrothermal pretreatment, filtering and washing to obtain zeolite precursor liquid;
and 2, adding a metal solution into the zeolite precursor solution, performing hydrothermal crystallization treatment, filtering, washing, drying and calcining to obtain the metal limited-area catalyst.
Preferably: the silicon source in the step 1 is inorganic silicon, orthosilicic acid or sodium silicate.
Preferably: the titanium source in the step 1 is titanium sulfate or titanium chloride.
Preferably: the carbonate in the step 1 is sodium carbonate or potassium carbonate.
Preferably: the alkali metal salt in the step 1 is sodium chloride or potassium chloride.
According to another aspect of the invention, there is provided the use of the metal-limited catalyst described above in the purification of automobile exhaust.
Compared with the prior art, the technical scheme of the invention has the advantages that the synthesis method is simple, the metal is encapsulated in the catalyst, the strategy of growing the metal catalyst by utilizing the unique pore canal limit of the mesoporous zeolite improves the interaction between the metal and the carrier, can obviously improve the stability of the catalyst, and provides a foundation for the practical application of the metal-zeolite catalyst.
Drawings
Other features, objects and advantages of the present invention will become more apparent upon reading of the detailed description of non-limiting embodiments, made with reference to the following drawings.
FIG. 1 is a photograph of HAADF and HAADF-STEM images of titanium silicalite-based metal Pt domain catalysts obtained in example 1 of the present invention;
FIG. 2 shows the Pt@TS-1 and Pt-supported titanium silicalite Pt/TS-1 prepared in comparative example 2 and PtO of the titanium silicalite-based metal Pt domain catalyst prepared in example 1 of the present invention 2 And Pt L3 side XANES and FT-EXAFS spectra of Pt foil, wherein a is XANES spectrum, the ordinate is normalized absorption coefficient (Normalized Absorption), b is FT-EXAFS spectrum, the ordinate is Intensity (Intensity);
FIG. 3 is a graph of the CO oxidation activity of the metal Pt-domain catalyst prepared in example 1, TS-1 prepared in comparative example 1, pt/TS-1 prepared in comparative example 2, versus different samples, with temperature on the abscissa and CO conversion on the ordinate; wherein a is a CO conversion rate chart of TS-1, pt@TS-1 and Pt/TS-1; b. c is a CO conversion chart of Pt@TS-1 and Pt/TS-1; d is a graph of the cyclic CO conversion of Pt@TS-1.
Detailed Description
Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the example embodiments to those skilled in the art. The same reference numerals in the drawings denote the same or similar structures, and thus a repetitive description thereof will be omitted.
In an embodiment of the invention, a metal confinement catalyst comprises zeolite and metal, wherein the zeolite is provided with mesoporous channels, and the metal is wrapped in the zeolite in a form of metal atoms or metal nanoclusters.
Mesoporous refers to pore channels with pore diameters between 2 and 50 nanometers, between micropores and macropores. Zeolite is a generic term for zeolite family minerals, which are aqueous alkali or alkaline earth aluminosilicate minerals. The zeolite has mesoporous channels. The metal is a metal atom or metal nanocluster grown in the zeolite in a confinement.
Preferably the confinement metal is present in the form of a metal atom or metal nanocluster. And preferably the mass of the metal grown in the confinement region is 0.1 to 2wt% of the total mass. Too low a metal content and low catalytic activity, if too high a metal content, it is not only difficult to form a zeolite framework having a specific topology, but also the metal easily migrates to the zeolite surface.
The activity and stability of the catalyst can be effectively improved by utilizing the finite field effect of mesoporous zeolite pore channels, so that the performance of the catalyst is integrally improved.
And preferably the metal is one or more of Pt, cu, bi, fe.
In addition, the metal confinement catalyst prepared by the embodiment of the invention has rich oxygen vacancy defects.
In addition, in the embodiment of the invention, the zeolite precursor liquid rich in zeolite sub-nano crystals is obtained through hydrothermal pretreatment, then the precursor liquid of metal solution is added, and the metal confinement catalyst based on mesoporous zeolite is obtained through a hydrothermal crystallization method.
Hydrothermal crystallization is a process in which an aqueous solution is used as a reaction medium in a specially-made closed reactor (e.g., autoclave, hydrothermal reactor), and a high-temperature, high-pressure reaction environment is created by heating the reactor, so that substances which are generally insoluble or insoluble are dissolved and recrystallized to form dispersed nanocrystal cores.
The hydrothermal pretreatment is to preheat the material for a period of time in a high-temperature and high-pressure reaction environment before hydrothermal crystallization.
The method specifically comprises the following steps:
and step 1, dissolving an inorganic silicon source, a titanium source/aluminum source, carbonate and alkali metal salt in an aqueous solution containing a structure directing agent for hydrothermal pretreatment, filtering and washing to obtain zeolite precursor liquid.
Among these, the preferred structure directing agent is tetrapropylammonium hydroxide (TPAOH) or tetraethylammonium hydroxide (TEAOH).
And preferably the silicon source is one of inorganic silicon, orthosilicic acid, sodium silicate and the like; the titanium source is one of titanium sulfate, titanium chloride and the like; the carbonate is one of sodium carbonate and potassium carbonate; the alkali metal salt is one of sodium chloride, potassium chloride, etc.
And preferably the concentration of alkali metal salt in the zeolite precursor solution is 1-3 mg/mL and the concentration of carbonate is 3-9 mg/mL. Wherein the atomic ratio of Si/M (M represents a metal Ti atom or Al atom) is 15 to 50.
In an embodiment of the invention, the zeolite sub-nanocrystalline is obtained by hydrothermal pretreatment at a certain temperature. Preferably, the temperature of the hydrothermal pretreatment is 120-200 ℃, and the time of the hydrothermal pretreatment is 6-12 h.
And 2, adding a metal solution into the zeolite precursor solution, reacting for a period of time, then performing hydrothermal crystallization treatment, and filtering, washing, drying and calcining to obtain the metal limited-area catalyst.
Preferably, the metal solution is a metal precursor solution formed by dissolving a metal source in a mixed solution of deionized water and ethylene glycol. Preferably, the volume ratio of the ethylene glycol to the water is 3-1.
Specifically, a certain metal source is weighed and dissolved in a mixed solution of deionized water and glycol, the obtained uniform mixed solution is added into a filtered and washed zeolite precursor solution to react for a period of time, and the zeolite precursor solution is transferred into a hydrothermal kettle to react for 12-24 hours under the condition of 120-200 ℃. And then filtering, washing, drying and calcining to finally obtain the zeolite-based metal limit catalyst in the embodiment of the invention.
And preferably the metal source is at least one of chloroplatinic acid, palladium nitrate, ferrous chloride, cuprous chloride, and the like.
Further, the concentration of the metal precursor solution is preferably 10 to 100mg/mL. And preferably the temperature of the hydrothermal crystallization is 120-200 ℃ and the time is 12-24 h. And preferably the temperature of subsequent drying is 80 to 120 ℃; the calcination temperature is 500-600 ℃ and the calcination time is 4-8 h.
In addition, the synthesis method of the embodiment of the invention is simple, the metal in the metal limited-area catalyst exists in the form of atoms or nanoclusters, and the obtained catalyst has excellent catalytic oxidation activity and stability, and can be applied to the fields of thermocatalysis and environmental catalysis, such as automobile tail gas purification.
Example 1
0.11g of sodium carbonate, 50mmol of orthosilicic acid and 0.05g of potassium chloride are dissolved in 6mL of H 2 O and 10g of tetrapropylammonium hydroxide (TPAOH, 50 wt%) were continuously stirred at 60℃for 30min to give solution 1.
Then 2mmol of titanium sulfate was dissolved in 4mL of H 2 O, solution 2 was obtained.
Then adding the solution 2 into the solution 1 dropwise, strongly stirring at 40 ℃ for 4 hours, transferring into a hydrothermal kettle, and carrying out hydrothermal pretreatment at 150 ℃ for 12 hours; finally, washing twice by using a mixed solution of ethanol and water; obtaining zeolite precursor liquid.
8mg of chloroplatinic acid was dissolved in 20mL of ethylene glycol and 10mL of H 2 O in the mixed solution. Then, it is added to the zeolite precursor liquid.
The mixed solution is subjected to hydrothermal crystallization at 150 ℃ for 24 hours.
Next, the mixture was cooled to room temperature, washed with ethanol and water, the upper aqueous solution was removed by centrifugation, dried overnight in a dry box at 80 ℃, and then calcined at 550 ℃ for 4 hours to obtain a titanium silicalite-based metal Pt limited catalyst pt@ts-1.
As shown in fig. 1, HAADF and HAADF-STEM images of the titanium silicalite-based metal Pt-limited catalyst prepared in example 1 of the present invention show that the samples prepared in example 1 of the present invention are nanoparticles of 300-500nm, the zeolite exhibits a loose porous morphology, and the zeolite surface has no significant metal Pt nanoparticles; meanwhile, the successful preparation of the metal Pt limited domain catalyst is suggested by exploring that Pt is coated in the zeolite in the form of nano particles or nano clusters by adopting a high-angle annular dark field scanning transmission electron microscope (HAADF-STEM) with aberration correction.
Comparative example 1
0.11g of sodium carbonate, 50mmol of orthosilicic acid and 0.05g of potassium chloride are dissolved in 6mL of H 2 O and 10g of tetrapropylammonium hydroxide (TPAOH, 50 wt%) were continuously stirred at 60℃for 30min to give solution 1.
Then 2mmol of titanium sulfate was dissolved in 4mL of H 2 O, solution 2 was obtained.
Then, the solution 2 was added dropwise to the solution 1, transferred to a hydrothermal kettle with vigorous stirring at 40℃for 4 hours, and subjected to hydrothermal crystallization at 150℃for 24 hours.
The mixture was cooled to room temperature, washed with ethanol and water, the upper aqueous solution was removed by centrifugation, dried overnight in a dry box at 80 ℃, and then calcined at 550 ℃ for 4 hours to obtain mesoporous titanium silicalite TS-1 having abundant oxygen vacancy defects.
Comparative example 2
0.11g of sodium carbonate, 50mmol of orthosilicic acid and 0.05g of potassium chloride are dissolved in 6mL of H 2 O and 10g of tetrapropylammonium hydroxide (TPAOH, 50 wt%) were continuously stirred at 60℃for 30min to give solution 1.
Then 2mmol of titanium sulfate was dissolved in 4mL of H 2 O, solution 2 was obtained.
Then, the solution 2 was added dropwise to the solution 1, transferred to a hydrothermal kettle with vigorous stirring at 40℃for 4 hours, and subjected to hydrothermal crystallization at 150℃for 24 hours.
The mixture was cooled to room temperature, washed with ethanol and water, the upper aqueous solution was removed by centrifugation, and dried overnight in a dry box at 80 ℃ to give uncalcined TS-1.
8mg of chloroplatinic acid was dissolved in 20mL of ethylene glycol and 10mL of H 2 To the O mixed solution, 4mL of 5NaBH at a concentration of 1mg/L was then added 4 The solution was stirred vigorously at 80℃for 6h. The uncalcined TS-1 was dissolved in the solution and reacted for 30min, and washed 3 times with ethanol and water.
The final product Pt/TS-1 was dried at 80℃and calcined at 550℃for 4 hours to give Pt-loaded titanium silicalite Pt/TS-1.
As shown in FIG. 2, the titanium silicalite-based metal Pt-limited-area catalyst Pt@TS-1 prepared in example 1 of the invention and the Pt-supported titanium silicalite Pt/TS-1, ptO prepared in comparative example 2 2 Pt L3 edge XANES and FT-EXAFS spectra of Pt foil. It can be found that: the Pt atoms in the Pt@TS-1 of the examples have a higher oxidation state than the Pt/TS-1, and the Pt in the Pt@TS-1 mainly exists in the form of Pt-O, unlike the Pt in the Pt/TS-1 mainly exists in the form of Pt-Pt. The result shows that mesoporous zeolite pore canal limit can regulate the electronic state of metal, and the existence of low oxidation state Pt helps to improve the catalytic activity.
Performance testing
Test 1:
100mg of the catalysts Pt@TS-1, TS-1 and Pt/TS-1 of example 1 and comparative example 2, respectively, were charged into a fixed bed quartz reactor and dried at 150℃for 1 hour. The reaction feed gas contains 1vol.% CO, 10vol.% O 2 And N 2 To balance the gas, the total flow rate was 200mL min -1 The temperature rising rate is 2 ℃/min.
The products were tested under steady state conditions using an on-line Gas Chromatograph (GC) equipped with a FID detector and their oxidative activity on CO was measured in the range of 30-300 ℃ and the results are shown in fig. 3 a.
Test 2:
100mg of the catalyst Pt@TS-1 of example 1 and Pt/TS-1 of comparative example 2 were charged into a fixed bed quartz reactor, respectively, and dried at 150℃for 1 hour. The reaction feed gas contains 1vol.% CO, 10vol.% O 2 8vol.% of H 2 O and N 2 To balance the gas, the total flow rate was 200mL min -1 The temperature rise rate was 2℃per minute, and the water resistance of the catalyst was measured.
The products were tested under steady state conditions using an on-line Gas Chromatograph (GC) equipped with a FID detector and their oxidative activity on CO was measured in the range of 30-300 ℃ and the results are shown in fig. 3 b.
Test 3:
100mg of the catalysts Pt@TS-1, pt/TS-1 of example 1 and comparative example 2, respectively, were charged into a fixed bed quartz reactor and dried at 150℃for 1h. The reaction feed gas contains 1vol.% CO, 10vol.% O 2 8vol.% of H 2 O, 200ppm SO 2 And N 2 To balance the gas, the total flow rate was 200mL min -1 The temperature rise rate was 2℃per minute, and the sulfur tolerance of the catalyst was measured.
The products were tested under steady state conditions using an on-line Gas Chromatograph (GC) equipped with a FID detector and their oxidative activity on CO was measured in the range of 30-300 ℃ and the results are shown in fig. 3 c.
Test 4:
100mg of the catalyst Pt@TS-1 was charged into a fixed bed quartz reactor and dried at 150℃for 1h. The reaction feed gas contains 1vol.% CO, 10vol.% O 2 8vol.% of H 2 O, 200ppm SO 2 And N 2 To balance the gas, the total flow rate was 200mL min -1 The temperature rise rate was 2℃per minute, and the durability and stability of the catalyst were measured.
Under steady state conditions, the products were detected using an on-line Gas Chromatograph (GC) equipped with a FID detector, and their oxidative activity on CO was measured in the range of 30-300 ℃. Once a cycle is completed, after the reactor has cooled to room temperature, a new cycle begins, the result of which is shown in fig. 3 d.
As shown in fig. 3, the CO oxidation activity of the catalyst is plotted against the different samples. It was found that the limited growth metal catalyst Pt@TS-1 of example 1 of the present invention can not only achieve complete conversion of 90% (T90) CO at 175℃but also exhibit excellent water and sulfur resistance at low noble metal content (-0.2 wt%). More importantly, the catalytic performance of the catalyst of example 1 remained essentially unchanged during the 3-cycle test, exhibiting excellent stability.
In conclusion, the synthesis method of the technical scheme of the invention is simple, the metal is encapsulated into the catalyst, the strategy of growing the metal catalyst by utilizing the unique pore canal limit of the mesoporous zeolite improves the interaction between the metal and the carrier, can obviously improve the stability of the catalyst, and provides a foundation for the practical application of the metal-zeolite catalyst.
The foregoing is a further detailed description of the invention in connection with the preferred embodiments, and it is not intended that the invention be limited to the specific embodiments described. It will be apparent to those skilled in the art that several simple deductions or substitutions may be made without departing from the spirit of the invention, and these should be considered to be within the scope of the invention.
Claims (10)
1. A metal-bound catalyst comprising a zeolite having mesoporous channels and a metal encapsulated within the zeolite in the form of metal atoms or metal nanoclusters.
2. The metal-limited catalyst of claim 1, wherein: the metal is one or more of Pt, cu, bi, fe.
3. The metal-limited catalyst of claim 1, wherein: the mass of the metal is 0.1-2 wt% of the total mass of the metal limiting catalyst.
4. The metal-limited catalyst of claim 1, wherein: the metal-limited catalyst has oxygen vacancy defects.
5. The method for preparing a metal-limited catalyst according to claim 1, wherein: the method comprises the following steps:
step 1, dissolving an inorganic silicon source, a titanium source/aluminum source, carbonate and alkali metal salt in an aqueous solution containing a structure directing agent for hydrothermal pretreatment, filtering and washing to obtain zeolite precursor liquid;
and 2, adding a metal solution into the zeolite precursor solution, performing hydrothermal crystallization treatment, filtering, washing, drying and calcining to obtain the metal limited-area catalyst.
6. The method for preparing a metal-limited catalyst according to claim 5, wherein: the silicon source in the step 1 is inorganic silicon, orthosilicic acid or sodium silicate.
7. The method for preparing a metal-limited catalyst according to claim 5, wherein: the titanium source in the step 1 is titanium sulfate or titanium chloride.
8. The method for preparing a metal-limited catalyst according to claim 5, wherein: the carbonate in the step 1 is sodium carbonate or potassium carbonate.
9. The method for preparing a metal-limited catalyst according to claim 5, wherein: the alkali metal salt in the step 1 is sodium chloride or potassium chloride.
10. Use of the metal-limited catalyst according to claim 1 in the purification of automobile exhaust.
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