CN112547132B - Preparation method of carrier catalyst of three-way catalytic converter - Google Patents
Preparation method of carrier catalyst of three-way catalytic converter Download PDFInfo
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- CN112547132B CN112547132B CN202011508908.5A CN202011508908A CN112547132B CN 112547132 B CN112547132 B CN 112547132B CN 202011508908 A CN202011508908 A CN 202011508908A CN 112547132 B CN112547132 B CN 112547132B
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- 239000003054 catalyst Substances 0.000 title claims abstract description 28
- 238000002360 preparation method Methods 0.000 title claims abstract description 19
- 230000003197 catalytic effect Effects 0.000 title claims abstract description 16
- 239000011248 coating agent Substances 0.000 claims abstract description 45
- 238000000576 coating method Methods 0.000 claims abstract description 45
- 239000000919 ceramic Substances 0.000 claims abstract description 37
- 229910052878 cordierite Inorganic materials 0.000 claims abstract description 33
- JSKIRARMQDRGJZ-UHFFFAOYSA-N dimagnesium dioxido-bis[(1-oxido-3-oxo-2,4,6,8,9-pentaoxa-1,3-disila-5,7-dialuminabicyclo[3.3.1]nonan-7-yl)oxy]silane Chemical compound [Mg++].[Mg++].[O-][Si]([O-])(O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2)O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2 JSKIRARMQDRGJZ-UHFFFAOYSA-N 0.000 claims abstract description 33
- 238000003756 stirring Methods 0.000 claims abstract description 28
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 26
- HSJPMRKMPBAUAU-UHFFFAOYSA-N cerium(3+);trinitrate Chemical compound [Ce+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O HSJPMRKMPBAUAU-UHFFFAOYSA-N 0.000 claims abstract description 25
- 239000006255 coating slurry Substances 0.000 claims abstract description 25
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 20
- 229910052782 aluminium Inorganic materials 0.000 claims abstract description 20
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims abstract description 20
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 20
- 239000010703 silicon Substances 0.000 claims abstract description 20
- 239000000843 powder Substances 0.000 claims abstract description 19
- 229940081733 cetearyl alcohol Drugs 0.000 claims abstract description 18
- GLDOVTGHNKAZLK-UHFFFAOYSA-N octadecan-1-ol Chemical compound CCCCCCCCCCCCCCCCCCO GLDOVTGHNKAZLK-UHFFFAOYSA-N 0.000 claims abstract description 18
- 229940051841 polyoxyethylene ether Drugs 0.000 claims abstract description 18
- 229920000056 polyoxyethylene ether Polymers 0.000 claims abstract description 18
- VXAUWWUXCIMFIM-UHFFFAOYSA-M aluminum;oxygen(2-);hydroxide Chemical compound [OH-].[O-2].[Al+3] VXAUWWUXCIMFIM-UHFFFAOYSA-M 0.000 claims abstract description 15
- 239000011812 mixed powder Substances 0.000 claims abstract description 14
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 13
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims abstract description 12
- 229910017604 nitric acid Inorganic materials 0.000 claims abstract description 12
- 238000001694 spray drying Methods 0.000 claims abstract description 12
- 238000001035 drying Methods 0.000 claims abstract description 11
- 239000002253 acid Substances 0.000 claims abstract description 9
- 238000007598 dipping method Methods 0.000 claims abstract description 9
- 229910001868 water Inorganic materials 0.000 claims abstract description 8
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 7
- 239000011148 porous material Substances 0.000 claims abstract description 7
- 239000007788 liquid Substances 0.000 claims abstract description 5
- 238000000034 method Methods 0.000 claims description 15
- 239000000725 suspension Substances 0.000 claims description 10
- 238000011068 loading method Methods 0.000 claims description 9
- 238000010992 reflux Methods 0.000 claims description 7
- BOTDANWDWHJENH-UHFFFAOYSA-N Tetraethyl orthosilicate Chemical compound CCO[Si](OCC)(OCC)OCC BOTDANWDWHJENH-UHFFFAOYSA-N 0.000 claims description 5
- 239000000758 substrate Substances 0.000 claims description 5
- 238000009833 condensation Methods 0.000 claims description 2
- 230000005494 condensation Effects 0.000 claims description 2
- LFQCEHFDDXELDD-UHFFFAOYSA-N tetramethyl orthosilicate Chemical compound CO[Si](OC)(OC)OC LFQCEHFDDXELDD-UHFFFAOYSA-N 0.000 claims description 2
- ZQZCOBSUOFHDEE-UHFFFAOYSA-N tetrapropyl silicate Chemical compound CCCO[Si](OCCC)(OCCC)OCCC ZQZCOBSUOFHDEE-UHFFFAOYSA-N 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims 2
- 125000000217 alkyl group Chemical group 0.000 claims 1
- 230000000052 comparative effect Effects 0.000 description 19
- 238000006243 chemical reaction Methods 0.000 description 13
- 239000000463 material Substances 0.000 description 8
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 7
- 235000012239 silicon dioxide Nutrition 0.000 description 7
- 230000000694 effects Effects 0.000 description 6
- 229910021426 porous silicon Inorganic materials 0.000 description 6
- 239000000377 silicon dioxide Substances 0.000 description 6
- WYTGDNHDOZPMIW-RCBQFDQVSA-N alstonine Natural products C1=CC2=C3C=CC=CC3=NC2=C2N1C[C@H]1[C@H](C)OC=C(C(=O)OC)[C@H]1C2 WYTGDNHDOZPMIW-RCBQFDQVSA-N 0.000 description 5
- 239000008367 deionised water Substances 0.000 description 5
- 229910021641 deionized water Inorganic materials 0.000 description 5
- 238000005303 weighing Methods 0.000 description 5
- 238000004299 exfoliation Methods 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 238000005406 washing Methods 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 238000007792 addition Methods 0.000 description 2
- 230000001070 adhesive effect Effects 0.000 description 2
- 238000007664 blowing Methods 0.000 description 2
- 229910002091 carbon monoxide Inorganic materials 0.000 description 2
- 239000000969 carrier Substances 0.000 description 2
- 229910000420 cerium oxide Inorganic materials 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 description 2
- 229910002706 AlOOH Inorganic materials 0.000 description 1
- 238000010521 absorption reaction Methods 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 238000004364 calculation method Methods 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 229910052593 corundum Inorganic materials 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002808 molecular sieve Substances 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 239000000376 reactant Substances 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229910052703 rhodium Inorganic materials 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 description 1
- 238000000527 sonication Methods 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N titanium dioxide Inorganic materials O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 1
- 229910001845 yogo sapphire Inorganic materials 0.000 description 1
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- 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
- B01J35/50—Catalysts, in general, characterised by their form or physical properties characterised by their shape or configuration
- B01J35/56—Foraminous structures having flow-through passages or channels, e.g. grids or three-dimensional monoliths
-
- 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
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/002—Mixed oxides other than spinels, e.g. perovskite
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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
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
- B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/56—Platinum group metals
- B01J23/63—Platinum group metals with rare earths or actinides
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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
- 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
- B01J35/61—Surface area
- B01J35/613—10-100 m2/g
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
- F01N3/28—Construction of catalytic reactors
- F01N3/2803—Construction of catalytic reactors characterised by structure, by material or by manufacturing of catalyst support
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
- F01N3/00—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust
- F01N3/08—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous
- F01N3/10—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust
- F01N3/24—Exhaust or silencing apparatus having means for purifying, rendering innocuous, or otherwise treating exhaust for rendering innocuous by thermal or catalytic conversion of noxious components of exhaust characterised by constructional aspects of converting apparatus
- F01N3/28—Construction of catalytic reactors
- F01N3/2803—Construction of catalytic reactors characterised by structure, by material or by manufacturing of catalyst support
- F01N3/2825—Ceramics
- F01N3/2828—Ceramic multi-channel monoliths, e.g. honeycombs
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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
- B01J2523/00—Constitutive chemical elements of heterogeneous catalysts
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- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/12—Improving ICE efficiencies
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Abstract
The invention provides a preparation method of a carrier catalyst of a three-way catalytic converter, which comprises the following steps: s1, dispersing pseudo-boehmite powder in water, dropwise adding a nitric acid solution for dispergation, and stirring for 1-5h at 70-90 ℃ to form alumina sol; dissolving a silicon source and cetearyl alcohol polyoxyethylene ether in ethanol, and performing spray drying to obtain mixed powder; adding cerium nitrate and the mixed powder into the aluminum sol to prepare coating slurry; s2, dipping the cordierite honeycomb ceramic carrier into the coating slurry, taking out, removing the redundant coating slurry in the carrier pore channel, drying, roasting in a muffle furnace at 500-600 ℃ for 2-5h, and repeating the steps for 2-4 times; s3, dipping the cordierite honeycomb ceramic carrier coated with the coating into chloroplatinic acid solution with pH of 2-3, taking out, removing redundant liquid, drying, and roasting in a muffle furnace at 500-600 ℃ for 1-4h to obtain the carrier catalyst.
Description
Technical Field
The invention belongs to the technical field of catalytic converters, and relates to a preparation method of a carrier catalyst of a three-way catalytic converter.
Background
In recent years, with the development of the automobile industry and the rapid increase of automobile holding capacity, the automobile exhaust gas brings serious pollution to the human living environmentHas attracted high attention from countries in the world. The method of adopting catalytic purification is an effective means for eliminating exhaust pollution. The three-way catalytic converter for purifying the tail gas of the automobile mainly comprises a carrier framework, a carrier active coating and a noble metal (Pt, Rh and Pd) active component. The carrier skeleton is usually selected from cordierite honeycomb ceramic bodies or metal carriers, wherein the ceramic carrier has high mechanical strength, small pressure drop, low thermal expansion coefficient and good thermal stability, so the honeycomb ceramic carrier is widely applied to the field of engine exhaust aftertreatment; compared with the prior art, the metal carrier has excellent high-temperature resistance and heat conductivity, and the metal has good ductility and is easy to process into the carrier with higher pore density. The specific surface area of the carrier is usually low, the narrow pore canal wall surface is smooth, the loading amount and stability of the active component are directly influenced, so the specific surface area of the carrier surface is often increased by a method of modifying the carrier surface by a coating in practical application, and the commonly used coating material mainly comprises Al2O3、TiO2And molecular sieves, and the like.
The coating material is required to have a proper pore-size structure and a high specific surface area, and in addition, the carrier framework and the coating are required to have good binding property and high-temperature thermal stability, so that the catalyst still keeps high activity under severe use conditions such as high-temperature thermal shock and the like, and the preparation process of the active coating is one of core technologies of preparation research of the automobile catalytic converter.
Disclosure of Invention
The invention provides a preparation method of a carrier catalyst of a three-way catalytic converter, which can improve the binding property of a coating and a carrier framework, and improve the specific surface area and the thermal stability of the coating, thereby improving the catalytic conversion activity of the carrier catalyst.
An object of the present invention is to provide a method for preparing a supported catalyst for a three-way catalytic converter, comprising the steps of:
s1, preparation of coating slurry: dispersing pseudo-boehmite powder in water, stirring to form a suspension, dripping a nitric acid solution under condensation reflux to decompose the gel, and stirring at 70-90 ℃ for 1-5h to form alumina sol; dissolving a silicon source and cetearyl alcohol polyoxyethylene ether in ethanol, uniformly stirring, and performing spray drying to obtain mixed powder; adding cerium nitrate and the mixed powder into the aluminum sol, and uniformly stirring to obtain coating slurry;
s2, dipping the cordierite honeycomb ceramic carrier in the coating slurry for 20-40min, taking out, removing the redundant coating slurry in the carrier pore channel, naturally drying at room temperature, drying at the temperature of 100-120 ℃ for 10-14h, roasting in a muffle furnace at the temperature of 500-600 ℃ for 2-5h, and repeating the steps for 2-4 times;
s3, supported catalyst: the cordierite honeycomb ceramic carrier coated with the coating is soaked in a chloroplatinic acid solution with the pH value of 2-3 (the pH value of the chloroplatinic acid solution is adjusted to be 2-3 by adding acid and/or alkali), the carrier is taken out after being soaked for 30-160s, the redundant liquid is removed, the carrier is dried for 2-10h at the temperature of 100 ℃ and is roasted for 1-4h at the temperature of 500 ℃ and 600 ℃ in a muffle furnace, and the carrier catalyst is prepared.
The silicon source and the cetearyl alcohol polyoxyethylene ether are dissolved in the ethanol, and in the spray drying process, the steric hindrance formed by the cetearyl alcohol polyoxyethylene ether limits the continuous accumulation of the silicon source, so that the further growth of the particles and the fusion and adhesion among the particles are prevented, and the uniform dispersion of the particles is facilitated; after spray drying, coating cetearyl alcohol polyoxyethylene ether on the surface of the silicon source, and improving the adhesive property between the coating material and the carrier by the surface of the cetearyl alcohol polyoxyethylene ether; during the calcination process, cetearyl alcohol polyoxyethylene ether on the surface of the silicon source is decomposed to form porous silicon dioxide. According to the invention, after the ethanol solution of the silicon source and the cetearyl alcohol polyoxyethylene ether is spray-dried, the ethanol solution is added into the aluminum sol, and porous silicon dioxide is generated after high-temperature roasting, so that the cordierite honeycomb ceramic carrier coating comprises alumina, cerium oxide and porous silicon dioxide, and the specific surface area and the thermal stability of the coating material are greatly improved.
Preferably, the mass fraction of the pseudo-boehmite powder in the suspension of the step S1 is 12-22 wt%. The mass fraction of AlOOH in the aluminum sol can influence the loading capacity of the coating, and in the initial preparation stage, the mass fraction of the pseudo-boehmite powder is controlled to be 12-22wt%, so that the proper loading capacity can be obtained.
Preferably, in step S1, press the key [ H ]+]/[Al3+]In a molar ratio of0.07-0.20 drop-wise addition of nitric acid solution.
Preferably, the concentration of the nitric acid solution is 1 to 5 mol/L.
Preferably, the mass ratio of the silicon source to the cetearyl alcohol polyoxyethylene ether is 1: (1-2).
Preferably, the silicon source is one or more of methyl orthosilicate, ethyl orthosilicate and propyl orthosilicate.
Preferably, the cetearyl polyoxyethylene ether has a molecular formula:
Preferably, the mass ratio of the pseudo-boehmite powder to the cerium nitrate to the mixed powder is (4-7): (0.8-1.2): (0.8-1.0), adding a certain amount of cerium nitrate and a certain amount of mixed powder into a certain amount of aluminum sol.
Preferably, in step S2, the cordierite honeycomb ceramic substrate has a coating loading of 10 to 20 wt%. The calculation method of the load rate comprises the following steps: before and after the ceramic carrier is coated, the ceramic carrier is weighed by an electronic balance, and the loading capacity of the coating is (the weight of the coated carrier-the initial weight of the carrier) × 100%/the initial weight of the carrier.
Compared with the prior art, the invention has the following beneficial effects:
(1) according to the invention, cerium nitrate is added into the aluminum sol to improve the thermal stability of the coating material;
(2) according to the invention, the silicon source and the cetearyl alcohol polyoxyethylene ether are dissolved in the ethanol, and the uniform dispersion of particles is facilitated in the spray drying process; after spray drying, coating cetearyl alcohol polyoxyethylene ether on the surface of the silicon source, and improving the adhesive property between the coating material and the carrier by the surface of the cetearyl alcohol polyoxyethylene ether; in the roasting process, the cetearyl alcohol polyoxyethylene ether on the surface of the silicon source is decomposed, so that porous silicon dioxide is favorably formed;
(3) according to the invention, after the ethanol solution of a silicon source and cetearyl alcohol polyoxyethylene ether is subjected to spray drying, the ethanol solution is added into the aluminum sol, and porous silicon dioxide is generated after high-temperature roasting, so that the cordierite honeycomb ceramic carrier coating comprises alumina, cerium oxide and porous silicon dioxide, and the specific surface area and the thermal stability of the coating material are greatly improved;
(4) the preparation method of the carrier catalyst of the catalytic converter is easy for large-scale industrialization, and the prepared carrier catalyst has excellent catalytic conversion activity, especially CO and C under the condition of low temperature3H8And the conversion efficiency of NOx is improved, and the excellent catalytic activity is still maintained under the high-temperature operation.
Drawings
FIG. 1 is a graph of conversion versus temperature for a supported catalyst prepared in accordance with example 3 of the present invention;
FIG. 2 is a graph showing the change of conversion rate with temperature of the supported catalyst prepared in comparative example 4 of the present invention.
Detailed Description
The technical solution of the present invention is further described and illustrated by the following specific examples. The raw materials used in the examples of the present invention are those commonly used in the art, and the methods used in the examples are those conventional in the art, unless otherwise specified.
Pseudo-boehmite powder is purchased from China aluminum industry Co., Ltd and is brand P-G-03;
cetearyl alcohol polyoxyethylene ether is AEO-10 and AEO-12 produced by Haian petrochemical plant of Jiangsu province;
the cordierite honeycomb ceramic carrier has the size of
Ningbo Kesen purifier Ltd, with a square hole shape, a porosity of 24.4%, a water absorption of 16.9%, and a bulk density of 501.5kg · m-3。
Example 1
This example produces a coated cordierite honeycomb ceramic support by:
s1, preparation of coating slurry: weighing 100g of pseudo-boehmite powder, putting the pseudo-boehmite powder into a three-necked flask, adding 450g of deionized water, stirring for 0.5h to form a suspension, and placing the suspension in a serpentine condenser tubeCondensed under reflux, [ H ]+]/[Al3+]Dropwise adding 2mol/L nitric acid solution with the molar ratio of 0.1, and stirring and reacting for 2 hours at 80 ℃ to form aluminum sol; dissolving 10g of ethyl orthosilicate and 10g of AEO-10 in 50g of ethanol, uniformly stirring, and performing spray drying to obtain mixed powder; adding 20g of cerium nitrate and the mixed powder into the prepared aluminum sol, and uniformly stirring to obtain coating slurry;
s2, dipping the cordierite honeycomb ceramic carrier subjected to acid washing and water washing pretreatment in the coating slurry for 25min, taking out, blowing off the redundant coating slurry in the carrier pore channel, naturally drying for 10h at room temperature, drying for 10h at 120 ℃, roasting for 3h at 560 ℃ in a muffle furnace, repeating the steps for 3 times, and calculating to obtain the coating load capacity of the cordierite honeycomb ceramic carrier to be 16.2 wt%. The cordierite honeycomb ceramic carrier coated with the coating is obtained.
Example 2
This example produces a coated cordierite honeycomb ceramic support by:
s1, preparation of coating slurry: weighing 100g of pseudo-boehmite powder, putting into a three-neck flask, adding 400g of deionized water, stirring for 25min to form a suspension, condensing and refluxing in a serpentine condenser tube according to the formula [ H ]+]/[Al3+]Dropwise adding 3mol/L nitric acid solution with the molar ratio of 0.12, and stirring and reacting at 85 ℃ for 2.5h to form alumina sol; dissolving 10g of ethyl orthosilicate and 12g of AEO-12 in 60g of ethanol, uniformly stirring, and performing spray drying to obtain mixed powder; adding 25g of cerium nitrate and the mixed powder into the prepared aluminum sol, and uniformly stirring to obtain coating slurry;
s2, dipping the cordierite honeycomb ceramic carrier subjected to acid washing and water washing pretreatment in the coating slurry for 30min, taking out, blowing off the redundant coating slurry in the carrier pore channel, naturally drying for 12h at room temperature, drying for 12h at 110 ℃, roasting for 2.5h at 540 ℃ in a muffle furnace, repeating the steps for 3 times, and calculating to obtain the coating load capacity of the cordierite honeycomb ceramic carrier to be 16.8 wt%. The cordierite honeycomb ceramic carrier coated with the coating is obtained.
Comparative example 1
Comparative example 1 a cordierite honeycomb ceramic support coated with a coating was prepared by the following procedure:
s1, preparation of coating slurry: weighing 100g of pseudo-boehmite powder, putting into a three-neck flask, adding 450g of deionized water, stirring for 0.5H to form a suspension, condensing and refluxing in a serpentine condenser tube according to the formula [ H ]+]/[Al3+]Dropwise adding 2mol/L nitric acid solution with the molar ratio of 0.1, and stirring and reacting for 2 hours at 80 ℃ to form aluminum sol; dissolving 10g of AEO-10 in 50g of ethanol, uniformly stirring, and performing spray drying to obtain powder; adding 20g of cerium nitrate and powder into the prepared aluminum sol, and uniformly stirring to prepare coating slurry;
step S2 the cordierite honeycomb ceramic substrate was calculated to have a coating loading of 15.8 wt% as in example 1. The cordierite honeycomb ceramic carrier coated with the coating is obtained.
Comparative example 2
Comparative example 2 a cordierite honeycomb ceramic support coated with a coating was prepared by the following procedure:
s1, preparation of coating slurry: weighing 100g of pseudo-boehmite powder, putting into a three-neck flask, adding 450g of deionized water, stirring for 0.5H to form a suspension, condensing and refluxing in a serpentine condenser tube according to the formula [ H ]+]/[Al3+]Dropwise adding 2mol/L nitric acid solution with the molar ratio of 0.1, and stirring at 80 ℃ for reaction for 2 hours to form aluminum sol; dissolving 10g of ethyl orthosilicate in 50g of ethanol, uniformly stirring, and performing spray drying to obtain powder; adding 20g of cerium nitrate and powder into the prepared aluminum sol, and uniformly stirring to obtain coating slurry;
step S2 the cordierite honeycomb ceramic substrate was calculated to have a coating loading of 15.6 wt% as in example 1. The cordierite honeycomb ceramic carrier coated with the coating is obtained.
Comparative example 3
Comparative example 3 a cordierite honeycomb ceramic support coated with a coating was prepared by the following procedure:
s1, preparation of coating slurry: weighing 100g of pseudo-boehmite powder, putting into a three-neck flask, adding 450g of deionized water, stirring for 0.5H to form a suspension, condensing and refluxing in a serpentine condenser tube according to the formula [ H ]+]/[Al3+]Dropwise adding 2mol/L nitric acid solution with the molar ratio of 0.1, and stirring and reacting for 2 hours at 80 ℃ to form aluminum sol; 20g of cerous nitrate and 10g of tetraethoxysilaneAdding 10g of AEO-10 into the prepared aluminum sol, and uniformly stirring to obtain coating slurry;
step S2 the cordierite honeycomb ceramic substrate was calculated to have a coating loading of 16.0 wt% as in example 1. The cordierite honeycomb ceramic carrier coated with the coating is obtained.
Determination of specific surface area of support
The specific surface areas of the coated cordierite honeycomb ceramic supports of examples 1-2 and comparative examples 1-3 were determined and their BET specific surface areas were determined by Micromeritics ASAP 2020M + C (Mac USA). The experimental data are shown in table 1.
Coating and Carrier binding test
The coating layer-to-carrier bonding strengths of the cordierite honeycomb ceramic carriers coated with the coating layers of examples 1 to 2 and comparative examples 1 to 3 were measured in a KUDOS-SK250H type ultrasonic cleaner, and the samples prepared in examples 1 to 2 and comparative examples 1 to 3 were placed in water at an ultrasonic power of 160W and a frequency of 25kHz, respectively, and subjected to ultrasonic vibration treatment for 20min, then taken out, dried, weighed, and the carrier coating peeling rate was calculated. Exfoliation rate (initial mass-post-sonication mass) 100%/initial mass
The experimental data are shown in table 1.
TABLE 1 specific surface area and exfoliation rate of the washcoats of examples 1-2 and comparative examples 1-3
As can be seen from Table 1, the washcoat prepared in examples 1-2 had a high specific surface area and a low exfoliation rate; comparative example 1 no silicon source was added, and the specific surface area of the prepared washcoat was greatly reduced; comparative example 2 no AEO-10 was added, resulting in a decrease in the binding of the coating to the carrier and a large increase in the exfoliation rate; comparative example 3 although the silicon source and AEO-10 were added, the silicon source and AEO-10 were directly added to the aluminum sol, and AEO-10 was not coated on the surface of the silicon source, resulting in a carrier coating having a lower specific surface area and a lower bonding force than those of example 1.
Example 3
The cordierite honeycomb ceramic carrier coated with the coating prepared in the example 1 is dipped in chloroplatinic acid solution with the pH value of 2.8, taken out after 100s of dipping, removed with redundant liquid, dried at 110 ℃ for 2h, and roasted in a muffle furnace at 560 ℃ for 2.5h to prepare the carrier catalyst.
Comparative example 4
The cordierite honeycomb ceramic carrier coated with the coating prepared in the comparative example 2 is soaked in a chloroplatinic acid solution with the pH value of 2.8, taken out after being soaked for 100s, removed of redundant liquid, dried at 110 ℃ for 2h, and roasted at 560 ℃ in a muffle furnace for 2.5h to prepare the carrier catalyst.
The activity evaluation of the supported catalysts prepared in example 3 and comparative example 4 was carried out in a fixed bed quartz tube reactor with a simulated gas composition of: 0.3% CO, 0.05% C3H8、0.05％NO、8％CO2、8％H2O and 0.8% O2By N2As an equilibrium gas. Space velocity of 40000h-1The activity of the catalyst was evaluated by raising the temperature from room temperature to 500 ℃ at a rate of 8 min/DEG C, and the conversion of each reactant was automatically calculated by the instrument. The change of the conversion rate with temperature of the supported catalyst prepared in example 3 is shown in FIG. 1, and the change of the conversion rate with temperature of the supported catalyst prepared in comparative example 4 is shown in FIG. 2. As can be seen from fig. 1 and 2, the supported catalyst of example 3 has higher catalytic conversion efficiency in a low-temperature environment.
In the above simulated gas, the CO conversion of the supported catalyst prepared in example 3 was maintained at 99.4% while the CO conversion of the supported catalyst prepared in comparative example 4 was reduced to 93.6% at a reaction temperature of 500 ℃ for 24 hours in continuous operation. The coating material prepared by the invention has good bonding property and high-temperature thermal stability with a carrier framework, so that the catalyst still keeps higher activity under harsh use conditions such as high temperature and the like.
The specific embodiments described herein are merely illustrative of the spirit of the invention and do not limit the scope of the invention. Various modifications or additions may be made to the described embodiments or alternatives may be employed by those skilled in the art without departing from the spirit or ambit of the invention as defined in the appended claims.
Claims (8)
1. A preparation method of a carrier catalyst of a three-way catalytic converter is characterized by comprising the following steps:
s1, preparation of coating slurry: dispersing pseudo-boehmite powder in water, stirring to form a suspension, dripping a nitric acid solution under condensation reflux to decompose the gel, and stirring at 70-90 ℃ for 1-5h to form alumina sol; dissolving a silicon source and cetearyl alcohol polyoxyethylene ether in ethanol, uniformly stirring, and performing spray drying to obtain mixed powder; adding cerium nitrate and the mixed powder into the aluminum sol, and uniformly stirring to obtain coating slurry;
s2, dipping the cordierite honeycomb ceramic carrier in the coating slurry for 20-40min, taking out, removing the redundant coating slurry in the carrier pore channel, naturally drying at room temperature, drying at the temperature of 100-120 ℃ for 10-14h, roasting in a muffle furnace at the temperature of 500-600 ℃ for 2-5h, and repeating the steps for 2-4 times;
s3, supported catalyst: dipping the cordierite honeycomb ceramic carrier coated with the coating into a chloroplatinic acid solution with the pH value of 2-3, taking out after dipping for 30-160s, removing redundant liquid, drying at the temperature of 100-120 ℃ for 2-10h, and roasting at the temperature of 500-600 ℃ in a muffle furnace for 1-4h to obtain a carrier catalyst;
the mass ratio of the silicon source to the cetearyl alcohol polyoxyethylene ether is 1 (1-2).
2. The method according to claim 1, wherein the mass fraction of the pseudo boehmite powder in the suspension of step S1 is 12 to 22 wt%.
3. The process according to claim 1, wherein in step S1, [ H ] is used+]/[Al3+]The nitric acid solution is dripped with the molar ratio of 0.07-0.20.
4. The production method according to claim 3, wherein the concentration of the nitric acid solution is 1 to 5 mol/L.
5. The preparation method according to claim 1, wherein the silicon source is one or more of methyl orthosilicate, ethyl orthosilicate and propyl orthosilicate.
6. The method of claim 1, wherein the cetearyl alcohol ethoxylate has the formula:
wherein R is C16-C18 alkyl, and n is 8-20.
7. The preparation method according to claim 1, wherein the mass ratio of the pseudo-boehmite powder to the cerium nitrate to the mixed powder is (4-7): (0.8-1.2): (0.8-1.0), adding the cerium nitrate and the mixed powder into the aluminum sol.
8. The production method according to claim 1, wherein in step S2, the cordierite honeycomb ceramic substrate has a coating loading of 10 to 20 wt%.
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| CN105521830A (en) * | 2016-01-29 | 2016-04-27 | 常州达奥新材料科技有限公司 | Preparation method of bone black based porous silicon carbide honeycomb ceramic catalyst carrier |
| CN111393155A (en) * | 2020-01-10 | 2020-07-10 | 重庆奥福精细陶瓷有限公司 | Thin-wall large-aperture cordierite honeycomb ceramic carrier and preparation method thereof |
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| CN105521830A (en) * | 2016-01-29 | 2016-04-27 | 常州达奥新材料科技有限公司 | Preparation method of bone black based porous silicon carbide honeycomb ceramic catalyst carrier |
| CN111393155A (en) * | 2020-01-10 | 2020-07-10 | 重庆奥福精细陶瓷有限公司 | Thin-wall large-aperture cordierite honeycomb ceramic carrier and preparation method thereof |
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