CN113134385A - Preparation method of honeycomb type ZSM-5-based coating catalyst - Google Patents
Preparation method of honeycomb type ZSM-5-based coating catalyst Download PDFInfo
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- CN113134385A CN113134385A CN202110329542.3A CN202110329542A CN113134385A CN 113134385 A CN113134385 A CN 113134385A CN 202110329542 A CN202110329542 A CN 202110329542A CN 113134385 A CN113134385 A CN 113134385A
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- 239000003054 catalyst Substances 0.000 title claims abstract description 96
- 238000000576 coating method Methods 0.000 title claims abstract description 67
- 239000011248 coating agent Substances 0.000 title claims abstract description 64
- 238000002360 preparation method Methods 0.000 title abstract description 10
- URGAHOPLAPQHLN-UHFFFAOYSA-N sodium aluminosilicate Chemical compound [Na+].[Al+3].[O-][Si]([O-])=O.[O-][Si]([O-])=O URGAHOPLAPQHLN-UHFFFAOYSA-N 0.000 claims abstract description 74
- 239000002808 molecular sieve Substances 0.000 claims abstract description 73
- 239000000919 ceramic Substances 0.000 claims abstract description 55
- 238000000034 method Methods 0.000 claims abstract description 28
- 238000006243 chemical reaction Methods 0.000 claims abstract description 21
- 239000011230 binding agent Substances 0.000 claims abstract description 20
- 230000003197 catalytic effect Effects 0.000 claims abstract description 20
- VXAUWWUXCIMFIM-UHFFFAOYSA-M aluminum;oxygen(2-);hydroxide Chemical compound [OH-].[O-2].[Al+3] VXAUWWUXCIMFIM-UHFFFAOYSA-M 0.000 claims abstract description 16
- 238000000498 ball milling Methods 0.000 claims abstract description 16
- 239000003292 glue Substances 0.000 claims abstract description 13
- 239000010936 titanium Substances 0.000 claims abstract description 12
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims abstract description 11
- 239000000853 adhesive Substances 0.000 claims abstract description 11
- 229910052719 titanium Inorganic materials 0.000 claims abstract description 11
- 230000001070 adhesive effect Effects 0.000 claims abstract description 10
- 239000002131 composite material Substances 0.000 claims abstract description 5
- 239000002243 precursor Substances 0.000 claims abstract description 4
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 18
- 239000002002 slurry Substances 0.000 claims description 18
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 17
- 229910052878 cordierite Inorganic materials 0.000 claims description 13
- 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 description 13
- 239000000843 powder Substances 0.000 claims description 12
- 239000012153 distilled water Substances 0.000 claims description 7
- 239000011148 porous material Substances 0.000 claims description 7
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 6
- 238000001035 drying Methods 0.000 claims description 6
- 238000011068 loading method Methods 0.000 claims description 6
- 239000002245 particle Substances 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 238000005406 washing Methods 0.000 claims description 5
- 238000005303 weighing Methods 0.000 claims description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical group O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 4
- 230000003301 hydrolyzing effect Effects 0.000 claims description 4
- 239000007787 solid Substances 0.000 claims description 4
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 3
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 claims description 3
- 239000002202 Polyethylene glycol Substances 0.000 claims description 3
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 3
- 238000007664 blowing Methods 0.000 claims description 3
- 238000011049 filling Methods 0.000 claims description 3
- 239000007788 liquid Substances 0.000 claims description 3
- 229910052748 manganese Inorganic materials 0.000 claims description 3
- 229920000609 methyl cellulose Polymers 0.000 claims description 3
- 239000001923 methylcellulose Substances 0.000 claims description 3
- 235000010981 methylcellulose Nutrition 0.000 claims description 3
- 230000007935 neutral effect Effects 0.000 claims description 3
- 229910017604 nitric acid Inorganic materials 0.000 claims description 3
- 229920001223 polyethylene glycol Polymers 0.000 claims description 3
- 238000012360 testing method Methods 0.000 claims description 3
- BNGXYYYYKUGPPF-UHFFFAOYSA-M (3-methylphenyl)methyl-triphenylphosphanium;chloride Chemical compound [Cl-].CC1=CC=CC(C[P+](C=2C=CC=CC=2)(C=2C=CC=CC=2)C=2C=CC=CC=2)=C1 BNGXYYYYKUGPPF-UHFFFAOYSA-M 0.000 claims description 2
- 229910052681 coesite Inorganic materials 0.000 claims description 2
- 229910052593 corundum Inorganic materials 0.000 claims description 2
- 229910052906 cristobalite Inorganic materials 0.000 claims description 2
- 238000002156 mixing Methods 0.000 claims description 2
- 239000004014 plasticizer Substances 0.000 claims description 2
- 239000000377 silicon dioxide Substances 0.000 claims description 2
- 229910052682 stishovite Inorganic materials 0.000 claims description 2
- 239000008399 tap water Substances 0.000 claims description 2
- 235000020679 tap water Nutrition 0.000 claims description 2
- XJDNKRIXUMDJCW-UHFFFAOYSA-J titanium tetrachloride Chemical compound Cl[Ti](Cl)(Cl)Cl XJDNKRIXUMDJCW-UHFFFAOYSA-J 0.000 claims description 2
- 229910052905 tridymite Inorganic materials 0.000 claims description 2
- 229910001845 yogo sapphire Inorganic materials 0.000 claims description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims 1
- 230000001413 cellular effect Effects 0.000 claims 1
- 239000003638 chemical reducing agent Substances 0.000 claims 1
- 239000006255 coating slurry Substances 0.000 claims 1
- 229910052739 hydrogen Inorganic materials 0.000 claims 1
- 239000001257 hydrogen Substances 0.000 claims 1
- 238000004537 pulping Methods 0.000 abstract 1
- 241000264877 Hippospongia communis Species 0.000 description 44
- 239000011572 manganese Substances 0.000 description 13
- 230000000694 effects Effects 0.000 description 10
- 238000005516 engineering process Methods 0.000 description 6
- 238000000746 purification Methods 0.000 description 5
- 230000002378 acidificating effect Effects 0.000 description 4
- 239000011247 coating layer Substances 0.000 description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- 239000010410 layer Substances 0.000 description 4
- 229910052751 metal Inorganic materials 0.000 description 4
- 239000002184 metal Substances 0.000 description 4
- 229910052720 vanadium Inorganic materials 0.000 description 4
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 4
- 238000001027 hydrothermal synthesis Methods 0.000 description 3
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 229910021536 Zeolite Inorganic materials 0.000 description 2
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 238000011156 evaluation Methods 0.000 description 2
- VCJMYUPGQJHHFU-UHFFFAOYSA-N iron(3+);trinitrate Chemical compound [Fe+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VCJMYUPGQJHHFU-UHFFFAOYSA-N 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 2
- 239000010457 zeolite Substances 0.000 description 2
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 1
- 238000002441 X-ray diffraction Methods 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 239000004202 carbamide Substances 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 238000012822 chemical development Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- IYRDVAUFQZOLSB-UHFFFAOYSA-N copper iron Chemical compound [Fe].[Cu] IYRDVAUFQZOLSB-UHFFFAOYSA-N 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 238000003618 dip coating Methods 0.000 description 1
- 238000007598 dipping method Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- IXQWNVPHFNLUGD-UHFFFAOYSA-N iron titanium Chemical compound [Ti].[Fe] IXQWNVPHFNLUGD-UHFFFAOYSA-N 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- MIVBAHRSNUNMPP-UHFFFAOYSA-N manganese(2+);dinitrate Chemical compound [Mn+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O MIVBAHRSNUNMPP-UHFFFAOYSA-N 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 230000010355 oscillation Effects 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 230000002265 prevention Effects 0.000 description 1
- 229910052594 sapphire Inorganic materials 0.000 description 1
- 230000035939 shock Effects 0.000 description 1
- 238000001228 spectrum Methods 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N titanium dioxide Inorganic materials O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 1
- 231100000331 toxic Toxicity 0.000 description 1
- 230000002588 toxic effect Effects 0.000 description 1
- 231100000419 toxicity Toxicity 0.000 description 1
- 230000001988 toxicity Effects 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
- B01J29/40—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively
- B01J29/48—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of the pentasil type, e.g. types ZSM-5, ZSM-8 or ZSM-11, as exemplified by patent documents US3702886, GB1334243 and US3709979, respectively containing arsenic, antimony, bismuth, vanadium, niobium tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
-
- 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
- B01J35/50—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
-
- 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
- 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
- B01J2229/186—After treatment, characterised by the effect to be obtained to introduce other elements into or onto the molecular sieve itself not in framework positions
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- 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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- 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
- Y02A50/2351—Atmospheric particulate matter [PM], e.g. carbon smoke microparticles, smog, aerosol particles, dust
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- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
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- Combustion & Propulsion (AREA)
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Abstract
A preparation method of a honeycomb type ZSM-5 based coating catalyst is characterized in that pseudo-boehmite and titanium glue are used as a composite binder precursor, a ceramic ball milling tank is used for ball milling and pulping, and a Mn series ZSM-5 molecular sieve based catalyst coating is prepared on the inner wall of a ceramic honeycomb hole. The molecular sieve based catalyst has high adhesive strength and can realize the requirement of one-time reaching coating load capacity, and the adhesive is used for NO of the Mn/ZSM-5 molecular sieve based catalystxThe low-temperature catalytic conversion performance can not be reduced, and the method is suitable for diesel vehicle tail gas NOxAnd 6, the purified national six reaches the discharge standard.
Description
Technical Field
The invention relates to a preparation method of a honeycomb type ZSM-5-based coating catalyst, in particular to a method for preparing a Mn series ZSM-5 molecular sieve based catalyst coating on the inner wall of a ceramic honeycomb hole, which is suitable for tail gas NO of a diesel vehicle (engine)xAnd (5) purifying.
Background
NO in tail gas discharged from diesel vehicle (engine)xRemoval (DeNO)x) Is an important part of the current exhaust gas purification of motor vehicles and general engines, in which ammonia from urea evaporation selectively catalyzes the reduction of NOxIs the tail gas NO of the prior diesel vehiclexOne of the most effective technologies for catalytic purification. With the publication of national six-emission standard of diesel vehicles in China (GB17691-2018 pollutant emission limit value and measurement method of heavy diesel vehicle (sixth stage in China)), NO of the diesel vehicle (engine) under starting and low-speed working conditions is improvedxThe low-temperature catalytic conversion performance requirement specifies that the vehicle provided with the vanadium-based SCR catalyst does not leak vanadium-containing compounds to the atmosphere in the normal life period. Strict high-standard emission requirements promote diesel engine host plants to abandon the mainstream vanadium TiO in five stages of China2The base catalyst technology is favored over the molecular sieve base catalyst technology, the molecular sieve base catalyst simultaneously has important technical characteristics of wide low-temperature active temperature window, NO toxic components such as vanadium and the like, good hydrothermal stability and sulfur toxicity resistance and the like, wherein the Mn series ZSM-5 molecular sieve base catalyst has excellent NOxLow temperature catalytic conversion performance (Lvgang, etc., engineering thermophysics, 2011,32(9):1597-xAnd (4) purifying the catalyst.
The molecular sieve based catalyst is applied to the exhaust emission purification of diesel vehicles (engines) and needs to be loaded on honeycomb carriers with honeycomb flow inner hole structures and thermal shock resistance, such as ceramic honeycombs and the like. As the national six-emission standard of diesel vehicles improves the service life of the catalyst in the catalytic converter from 8 kilometers to more than 16 kilometers of the national five-emission standard, the method provides very high requirements for the anti-washing and anti-falling performance of the molecular sieve based catalyst coating on the ceramic honeycomb, namely the coating preparation technology. Because the molecular sieve powder has less surface hydroxyl groups and poorer self-adhesive property, a coating with higher adhesive strength is difficult to form on a honeycomb carrier, and a binder is often added into a molecular sieve-based coating catalyst to meet the requirement of adhesive life strength. At the same time, in coating the catalystThe addition of the binder often causes the blockage of molecular sieve pores to reduce the dynamic diffusion effect of the catalyst, the coating of active components in the molecular sieve reduces the number of active centers participating in reaction, the interaction between the binder and the active centers such as Mn active components and the like, and the addition of the binder can influence the diesel vehicle tail gas NO of the molecular sieve-based coating catalystxCatalytic conversion performance. Therefore, the preparation technology of the ceramic honeycomb type molecular sieve based coating catalyst is a difficult production technology.
The molecular sieve is attached to the ceramic honeycomb by mainly using a hydrothermal growth method and a coating method. The hydrothermal growth method does not need an additional binder, has high adhesive strength, but has a thin catalyst coating layer, and is difficult to adapt to the long-condition service life requirement of diesel vehicle tail gas purification, so the coating method of the additional binder is basically adopted in the actual production process. Chinese patent ZL201510111018.3 discloses a method for preparing a molecular sieve coating on a metal carrier, wherein a ZSM-5 molecular sieve with higher bonding strength is obtained on the metal carrier by adopting alumina as a binder, but the patent does not describe the influence of the coating on the activity of a catalyst. China CN201310034762.9 discloses an oxidation catalyst for purifying diesel engine exhaust gas and a preparation method thereof, the method adds water into pseudo-boehmite, alumina and composite oxide, ball-mills the mixture into slurry, adds a molecular sieve into the slurry, adjusts the pH value, and stirs the mixture to prepare a coating, but the content of the molecular sieve in the coating prepared by the method is lower and is only 20-35%. Chinese patent No. cn200610013468.x discloses a preparation method of catalyst with micron-sized zeolite molecular sieve coated on the surface of carrier, after the metal carrier is pretreated by hydrochloric acid, it is dip-coated with suspension containing zeolite molecular sieve, and through multiple dip-coating, the thickness of molecular sieve coating layer can meet the requirements. Chinese patent CN1792431 discloses a new Al-containing coating2O3Is an inner layer carrier, TiO2The composite carrier which is an outer layer carrier is coated on the cordierite ceramic honeycomb and is loaded with an active component V2O5And WO3Integral catalystHowever, it is difficult to sufficiently contact the active component with Al in the bottom layer, and it is difficult to sufficiently exert the catalyst new energy. Chinese patent CN104549532 discloses that acidic silica sol, acidic alumina sol or titanium sol is prepared on cordierite ceramic honeycomb by hydrothermal synthesis method, and the measured strength peeling rate of the coating is below 5%, but it does not explain how the coating has influence on the catalyst performance. Chinese patent CN104785289 discloses a preparation method of a molecular sieve catalyst coated on a metal carrier, which is simple and convenient to prepare, but the performance of the catalytic active component is reduced due to excessive use of alumina and pseudo-boehmite as binders. Chinese patent CN105148914 discloses a layer of Al on ceramic honeycomb2O3The coating then supports the Fe catalyst, its H2The temperature at the top of the TPR reduction peak shifts significantly to a lower temperature, but the coating strength shifts with NOxThe catalytic conversion window is not relevant. Chinese patent CN107597178 discloses a method for preparing alpha-Al2O3The prepared monolithic molecular sieve type catalyst is a binder, the NO conversion rate of the catalyst is more than 90% at 225-375 ℃, the coating shedding rate is 7.35% at the lowest, but the loading capacity is 4.28% (about 21.91g/L), and the durable and sufficient catalytic performance is difficult to provide. Chinese patent CN105413740 discloses a Fe modified molecular sieve catalyst prepared by ion exchange method, and then coated on a ceramic honeycomb by using pseudo-boehmite and acidic silica sol as binders, the active components of the catalyst prepared by the method can be fully diffused in the pore channels of the molecular sieve, but there is still room for improvement at 200 ℃ at 50% conversion rate. Chinese patent CN110947414 discloses modifying TiO with iron salt2Preparing an integral iron-titanium coating after sol dissolving, and then preparing the integral iron-copper bimetallic molecular sieve catalyst by using pseudo-boehmite as a binder, wherein the coating falling rate can reach 1.77%, the loading capacity can reach 19.66%, but the 85% NO conversion window is 240-560 ℃, and a low-temperature offset space is still left in the temperature conversion window. Chinese patent CN106166493 discloses a method for modifying cordierite ceramic honeycomb by using ferric nitrate and the like, then dipping the cordierite ceramic honeycomb in manganese nitrate solution to load Mn component, wherein denitration rate at 125-225 ℃ reaches more than 80%, however, because the method has no intermediate carrier, the cordierite ceramic honeycomb can not provide more surface area to attach catalyst component, so that the monolithic type catalyst component can be attached to the monolithic type catalyst componentThe active lifetime of the catalyst is potentially at a greater risk. In addition, many documents report that the strength of the monolithic catalyst coating can be improved after the binder pseudo-boehmite or the acidic silica sol is added (Suncke et al, environmental pollution and prevention, 2013,35(11): 37-41; gold derivatives, chemical development, 2019,38(03): 271-278; and the like), but the catalytic performance of the monolithic catalyst coating has negative effect.
Disclosure of Invention
The invention aims to provide a method for preparing a Mn-series ZSM-5 molecular sieve based catalyst coating on the inner wall of a ceramic honeycomb hole, which adopts pseudo-boehmite and titanium glue as binder precursors, not only can form a large amount of molecular sieve catalyst coatings with higher adhesive strength in the ceramic honeycomb hole and easily realize the one-time achievement of the requirement of coating load capacity, but also the binder can be used for NO of the Mn/ZSM-5 molecular sieve catalystxThe low-temperature catalytic conversion performance is not reduced. The method comprises the following specific steps:
(1) pretreating a cordierite ceramic honeycomb carrier: immersing the ceramic honeycomb carrier in a nitric acid solution with the concentration of 0.5-1.5 mol/L for 6-8 hours at room temperature, taking out the ceramic honeycomb carrier, rinsing the ceramic honeycomb carrier with clean tap water until the washing liquid is neutral, drying the ceramic honeycomb carrier for 2-3 hours at the temperature of 100-120 ℃ in an air atmosphere, and roasting the ceramic honeycomb carrier for 150-180 minutes at the temperature of 250-300 ℃; the ceramic honeycomb carrier is a cordierite honeycomb.
(2) Pre-bonding powder Mn/ZSM-5 molecular sieve catalyst: weighing and adding citric acid solid particles accounting for 15-20% of the mass of the molecular sieve, plasticizer polyethylene glycol accounting for 0.5-1% of the mass of the molecular sieve and distilled water accounting for 65-70% of the mass of the molecular sieve in the added Mn/ZSM-5 powder catalyst in a ceramic ball milling tank, and carrying out ball milling for 30 minutes at the rotating speed of 110-150 revolutions per minute; the catalyst is 5% Mn/ZSM-5 molecular sieve catalyst, wherein the molecular sieve is SiO2/Al2O3The molar ratio is 25 to 50.
(3) Preparing slurry: weighing pseudo-boehmite accounting for 85-95% of the mass of the molecular sieve and titanium glue accounting for 0.4-2.9 times of the mass of the molecular sieve into a ceramic ball milling tank, adding methyl cellulose accounting for 1-1.5% of the mass of the molecular sieve, distilled water accounting for 200-250% of the mass of the molecular sieve and citric acid solid particles accounting for 10-15% of the mass of the molecular sieve, uniformly mixing, continuously adding the pre-gelatinized molecular sieve catalyst slurry obtained in the step (2), and carrying out ball milling for 120 minutes at the rotating speed of 120-150 revolutions per minute; and adjusting the pH value of the obtained slurry to 8-9 by using ammonia water with the concentration of 2 mol/L. The pseudo-boehmite glue is obtained by hydrolyzing aluminum nitrate, and the water content is 65-75%; the titanium glue is prepared by hydrolyzing titanium tetrachloride, and the water content is 70-85%.
(4) Preparing a coating: and (3) filling the cordierite ceramic honeycomb obtained in the step (1) with the slurry obtained in the step (3), and then blowing the slurry with clean compressed air to uniformly coat the slurry in honeycomb channels, so that the dry-based loading of the coating is not lower than 80g/L (calculated by the volume of the ceramic honeycomb). The coated ceramic honeycomb is dried in the shade at room temperature for not less than 2 hours, then dried at 100 ℃ for more than 4 hours in the air atmosphere, and then roasted at 350 ℃ for 30 minutes and at 550 ℃ for 4 hours.
(5) The method for measuring the strength of the coating comprises the following steps: testing the adhesion strength of the coating by using an ultrasonic impact method on the ceramic honeycomb loaded with the catalyst coating obtained in the step (4); loading the loaded and dried and roasted honeycomb type molecular sieve coating catalyst into a container such as a beaker, and adding distilled water to ensure that the catalyst is submerged; using an ultrasonic oscillation cleaner with 40KHz and 130W power, adjusting to 100 percent of output power, oscillating the sample for 20 minutes, taking out the sample, drying the sample at 100-120 ℃ for more than 3 hours, and calculating the coating shedding rate according to the dry-based coating amount, wherein the shedding rate is less than or equal to 8 percent.
(6) The method for testing the NO catalytic conversion performance of the honeycomb molecular sieve coating catalyst comprises the following steps: the obtained monolithic catalyst is placed in an exhaust gas evaluation system, and the gas distribution is 6 percent O2、1000ppmNO、1100ppmNH3、N2Used as balance gas. 5000h-1The activity of the honeycomb type coating catalyst is tested at an airspeed of 50000h-1The catalyst activities of the coated catalyst tabletted particles (40-60 mesh) and the binder-free powder tabletted catalyst (40-60 mesh) were compared.
The honeycomb molecular sieve coating catalyst prepared by the method has the characteristics of large coating amount of the molecular sieve coating, strong adhesion between the coating and the carrier, and small influence of the binder on the activity. The space velocity is 5000h-1Under the condition of ignition temperature T50(NO conversion 50%) lowTo 125 ℃ and T90(NO conversion rate is more than 90%) window can reach 200-380 deg.C. The honeycomb type Mn series ZSM-5 molecular sieve based coating catalyst obtained by the invention has good adhesive strength, can meet the requirement of load capacity by one-time coating, has simple production process, good compatibility of equipment for realizing the process and the existing three-way catalyst production equipment of motor vehicles, and provides a simple and convenient large-scale production process for commercializing the diesel vehicle tail gas purification catalyst meeting the emission requirements of the national six countries.
Drawings
FIG. 1 is an XRD pattern of the molecular sieve coated catalyst and the powder catalyst obtained in the example.
FIG. 2 is a graph of the catalytic NO conversion performance of the honeycomb molecular sieve-coated catalyst obtained in the example.
FIG. 3 is a graph of the catalytic NO conversion performance of the molecular sieve coated catalyst and the powder catalyst obtained in the example.
Detailed Description
The present invention will be described in detail below with reference to specific examples, but it should be understood that the present invention is not limited to the examples.
Example 1:
(1) immersing a cordierite ceramic honeycomb (phi 20mm multiplied by 25mm) carrier with 400 pores per square inch in a nitric acid solution with the concentration of 1mol/L for 8 hours at room temperature, taking out the carrier, washing the carrier with water until the washing liquid is neutral, and then drying the carrier for 3 hours at 120 ℃ and roasting the carrier for 180 minutes at 250 ℃ in an air atmosphere;
(2) weighing 10g of 5% Mn/ZSM-5 molecular sieve catalyst powder, 1.5g of citric acid and 0.08g of polyethylene glycol, adding into a ceramic ball milling tank, adding 10mL of distilled water, and ball milling for 30 minutes at the rotating speed of the ball mill of 120 revolutions per minute;
(3) 9.231g of pseudo-boehmite gel (with the water content of 67.5 percent), 19.231g of titanium gel (with the water content of 84.4 percent), 1g of citric acid, 0.12g of methylcellulose and 20mL of distilled water are weighed and added into the ceramic ball milling tank in the step (2), ball milling is carried out for 120 minutes at the rotating speed of the ball mill of 120 revolutions per minute, and the pH value of the obtained slurry is adjusted to about 8.5 by using ammonia water with the concentration of 2mol per L.
(4) And (3) filling the cordierite ceramic honeycomb obtained in the step (1) with the slurry obtained in the step (3), and then blowing the slurry by using air compression gas to ensure that the slurry is uniformly coated in the honeycomb pore channels. The coated ceramic honeycomb was dried in the shade at room temperature for 2 hours, then dried at 100 ℃ for 3 hours in an air atmosphere, and then fired at 350 ℃ for 30 minutes and 550 ℃ for 4 hours. The dry content of the coating was 139.6 g/L.
The ceramic honeycomb carrier loaded with the catalyst coating layer obtained in example 1 was tested for the adhesion strength of the coating layer by the ultrasonic impact method. The sample was shaken for 20 minutes with an ultrasonic shaker at 40KHz, 130W power with 100% output power, and taken out and dried at 120 ℃ for 180 minutes. The coating peeling rate was calculated as the dry basis coating amount and was 6.73%. From the XRD spectrum (fig. 1) of the sample obtained in example 1, it can be seen that the XRD diffraction peaks of the molecular sieve coated catalyst are consistent with those of the Mn/ZSM-5 molecular sieve powder, which indicates that the structural features of the molecular sieve catalyst in the coating are not damaged and the coating still shows a stronger molecular sieve catalyst structure. And (3) placing the monolithic catalyst obtained in the step (4) into an exhaust gas evaluation system, wherein the gas distribution is 6% O2、1000ppmNO、1100ppmNH3、N2For balancing qi, 5000h-1The catalytic activity of the catalyst is tested at space velocity, and the result is shown in figure 2. The prepared honeycomb type molecular sieve coating catalyst NO catalytic conversion ignition temperature T50Is 150 ℃ and T90The window is 200-380 ℃. Space velocity 50000mL-1.h-1Comparing the catalyst activity of the catalyst coating tablet particles (40-60 meshes) with the catalyst activity of the binder-free powder tablet catalyst (40-60 meshes) shown in figure 3, the catalyst coating activity T is shown after the binder is added50Is 150 ℃ and T90The window is 190-380 ℃, compared with the powder catalyst T without the binder50(240 ℃ C.) and T90The low-temperature catalytic activity performance of the catalyst is not reduced but is better at the low temperature, and the T is between 300 and 425 DEG C50And T90The windows are respectively shifted to the low temperature by 90 ℃ and 110 ℃, and the better low-temperature NO catalytic conversion performance is shown. The results of the examples show that the honeycomb type Mn series ZSM-5 molecular sieve based catalyst prepared by the invention has higher coating strength, and the binder does not cause the reduction of the catalyst activity, but improves and enhances the catalytic performance of the Mn series ZSM-5 molecular sieve based catalyst, thereby showing that the method is suitable for the preparation of the catalystFeasibility of the process.
Claims (4)
1. A process for preparing the catalyst with cellular ZSM-5-base coating includes such steps as preparing Mn-series ZSM-5-molecular sieve-base catalyst coating on the internal surface of ceramic honeycomb pores by using pseudo-boehmite and Ti adhesive as the precursor of composite adhesive, forming a great deal of molecular sieve-base catalyst coating with high adhesion strength in the pores of ceramic honeycomb pores, and applying the adhesive to the NO of Mn/ZSM-5-molecular sieve-base catalystxThe low-temperature catalytic conversion performance cannot be reduced; the method specifically comprises the following steps:
(1) pretreating a cordierite ceramic honeycomb carrier: immersing the ceramic honeycomb carrier in a nitric acid solution with the concentration of 0.5-1.5 mol/L for 6-8 hours at room temperature, taking out the ceramic honeycomb carrier, rinsing the ceramic honeycomb carrier with clean tap water until the washing liquid is neutral, drying the ceramic honeycomb carrier for 2-3 hours at the temperature of 100-120 ℃ in an air atmosphere, and roasting the ceramic honeycomb carrier for 150-180 minutes at the temperature of 250-300 ℃; the ceramic honeycomb carrier is a cordierite honeycomb;
(2) pre-bonding powder Mn/ZSM-5 molecular sieve catalyst: weighing and adding citric acid solid particles accounting for 15-20% of the mass of the molecular sieve, plasticizer polyethylene glycol accounting for 0.5-1% of the mass of the molecular sieve and distilled water accounting for 65-70% of the mass of the molecular sieve in the added Mn/ZSM-5 powder catalyst in a ceramic ball milling tank, and carrying out ball milling for 30 minutes at the rotating speed of 110-150 revolutions per minute; the catalyst is 5% Mn/ZSM-5 molecular sieve catalyst, wherein the molecular sieve is SiO2/Al2O3The molar ratio is 25-50;
(3) preparing slurry: weighing pseudo-boehmite accounting for 85-95% of the mass of the molecular sieve and titanium glue accounting for 0.4-2.9 times of the mass of the molecular sieve into a ceramic ball milling tank, adding methyl cellulose accounting for 1-1.5% of the mass of the molecular sieve, distilled water accounting for 200-250% of the mass of the molecular sieve and citric acid solid particles accounting for 10-15% of the mass of the molecular sieve, uniformly mixing, continuously adding the pre-gelatinized molecular sieve catalyst slurry obtained in the step (2), and carrying out ball milling for 120 minutes at the rotating speed of 120-150 revolutions per minute; adjusting the pH value of the obtained slurry to 8-9 by using ammonia water with the concentration of 2 mol/L; the pseudo-boehmite glue is obtained by hydrolyzing aluminum nitrate, and the water content is 65-75%; the titanium glue is obtained by hydrolyzing titanium tetrachloride, and the water content is 70-85%;
(4) preparing a coating: filling the cordierite ceramic honeycomb obtained in the step (1) with the slurry obtained in the loading step (3), and then blowing the slurry with clean compressed air to uniformly coat the slurry in honeycomb channels to obtain the dry basis loading of the coating of not less than 80g/L (calculated by the volume of the ceramic honeycomb); drying the coated ceramic honeycomb in the shade at room temperature for not less than 2 hours, then drying the ceramic honeycomb for more than 4 hours at 100 ℃ in an air atmosphere, then roasting the ceramic honeycomb for 30 minutes at 350 ℃, and roasting the ceramic honeycomb for 4 hours at 550 ℃;
(5) testing the adhesion strength of the coating by using an ultrasonic impact method on the ceramic honeycomb loaded with the catalyst coating obtained in the step (4), and carrying out NH (hydrogen) under certain reaction conditions3Is the NO catalytic conversion performance of the reducing agent.
2. The method of claim 1, wherein: preparing a Mn series ZSM-5 molecular sieve based catalyst coating on the inner wall of the ceramic honeycomb holes.
3. The method of claim 1, wherein: pseudo-boehmite and titanium glue are used as a precursor of the composite binder; the amount of the pseudo-boehmite glue is 85-95% of the mass of the molecular sieve, and the amount of the titanium glue is 0.4-2.9 times of the mass of the molecular sieve; the water content of the pseudo-boehmite glue is 65-75%, and the water content of the titanium glue is 70-85%.
4. The method of claim 1, wherein: and ball-milling the catalyst coating slurry in a ceramic ball-milling tank at a rotation speed of 120-150 rpm for 120 minutes.
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