CN107233912B - Two-stage catalyst for diesel vehicle tail gas treatment and preparation method thereof - Google Patents
Two-stage catalyst for diesel vehicle tail gas treatment and preparation method thereof Download PDFInfo
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- CN107233912B CN107233912B CN201710485488.5A CN201710485488A CN107233912B CN 107233912 B CN107233912 B CN 107233912B CN 201710485488 A CN201710485488 A CN 201710485488A CN 107233912 B CN107233912 B CN 107233912B
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- 239000003054 catalyst Substances 0.000 title claims abstract description 287
- 238000002360 preparation method Methods 0.000 title claims description 89
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 claims abstract description 83
- 239000002808 molecular sieve Substances 0.000 claims abstract description 75
- 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 63
- JEIPFZHSYJVQDO-UHFFFAOYSA-N iron(III) oxide Chemical group O=[Fe]O[Fe]=O JEIPFZHSYJVQDO-UHFFFAOYSA-N 0.000 claims abstract description 37
- 239000002245 particle Substances 0.000 claims abstract description 34
- 238000006243 chemical reaction Methods 0.000 claims abstract description 33
- NUJOXMJBOLGQSY-UHFFFAOYSA-N manganese dioxide Chemical group O=[Mn]=O NUJOXMJBOLGQSY-UHFFFAOYSA-N 0.000 claims abstract description 27
- 229910052763 palladium Inorganic materials 0.000 claims abstract description 12
- 229910052697 platinum Inorganic materials 0.000 claims abstract description 12
- 229910052703 rhodium Inorganic materials 0.000 claims abstract description 12
- 239000002105 nanoparticle Substances 0.000 claims description 95
- 239000011258 core-shell material Substances 0.000 claims description 45
- ZMANZCXQSJIPKH-UHFFFAOYSA-N Triethylamine Chemical compound CCN(CC)CC ZMANZCXQSJIPKH-UHFFFAOYSA-N 0.000 claims description 42
- 238000001027 hydrothermal synthesis Methods 0.000 claims description 18
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Substances [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 18
- KDLHZDBZIXYQEI-UHFFFAOYSA-N palladium Substances [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims description 17
- 239000002904 solvent Substances 0.000 claims description 14
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims description 13
- 235000011114 ammonium hydroxide Nutrition 0.000 claims description 13
- 229910052684 Cerium Inorganic materials 0.000 claims description 12
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 claims description 12
- 239000010948 rhodium Substances 0.000 claims description 12
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 10
- 238000000975 co-precipitation Methods 0.000 claims description 9
- 238000011068 loading method Methods 0.000 claims description 6
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 5
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims description 5
- 229910052802 copper Inorganic materials 0.000 claims description 5
- 239000010949 copper Substances 0.000 claims description 5
- 229910052742 iron Inorganic materials 0.000 claims description 5
- 229910052748 manganese Inorganic materials 0.000 claims description 5
- 239000011572 manganese Substances 0.000 claims description 5
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 claims description 5
- 229920000642 polymer Polymers 0.000 claims 1
- 239000007789 gas Substances 0.000 abstract description 108
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 abstract description 85
- 230000000694 effects Effects 0.000 abstract description 16
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 abstract description 8
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 abstract description 7
- 229910052799 carbon Inorganic materials 0.000 abstract description 7
- 230000008030 elimination Effects 0.000 abstract description 6
- 238000003379 elimination reaction Methods 0.000 abstract description 6
- 229910021529 ammonia Inorganic materials 0.000 abstract description 2
- 238000003756 stirring Methods 0.000 description 77
- 239000000243 solution Substances 0.000 description 47
- 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 description 33
- 238000001035 drying Methods 0.000 description 32
- 238000010438 heat treatment Methods 0.000 description 31
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 31
- 229920000036 polyvinylpyrrolidone Polymers 0.000 description 30
- 235000013855 polyvinylpyrrolidone Nutrition 0.000 description 30
- WHNWPMSKXPGLAX-UHFFFAOYSA-N N-Vinyl-2-pyrrolidone Chemical compound C=CN1CCCC1=O WHNWPMSKXPGLAX-UHFFFAOYSA-N 0.000 description 27
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 24
- 238000001704 evaporation Methods 0.000 description 22
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 21
- 229910052593 corundum Inorganic materials 0.000 description 21
- 229910001845 yogo sapphire Inorganic materials 0.000 description 21
- 239000008367 deionised water Substances 0.000 description 20
- 229910021641 deionized water Inorganic materials 0.000 description 20
- 239000000203 mixture Substances 0.000 description 20
- 238000005303 weighing Methods 0.000 description 18
- 230000000052 comparative effect Effects 0.000 description 15
- NLKNQRATVPKPDG-UHFFFAOYSA-M potassium iodide Chemical compound [K+].[I-] NLKNQRATVPKPDG-UHFFFAOYSA-M 0.000 description 15
- 238000009210 therapy by ultrasound Methods 0.000 description 15
- 239000000919 ceramic Substances 0.000 description 14
- 239000001267 polyvinylpyrrolidone Substances 0.000 description 12
- 229910052751 metal Inorganic materials 0.000 description 11
- 239000002184 metal Substances 0.000 description 11
- 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 10
- 229920003081 Povidone K 30 Polymers 0.000 description 9
- 238000000227 grinding Methods 0.000 description 9
- 238000012216 screening Methods 0.000 description 9
- IOLCXVTUBQKXJR-UHFFFAOYSA-M potassium bromide Chemical compound [K+].[Br-] IOLCXVTUBQKXJR-UHFFFAOYSA-M 0.000 description 8
- 238000010531 catalytic reduction reaction Methods 0.000 description 7
- 229910000069 nitrogen hydride Inorganic materials 0.000 description 7
- 238000001354 calcination Methods 0.000 description 6
- 239000007795 chemical reaction product Substances 0.000 description 6
- XTVVROIMIGLXTD-UHFFFAOYSA-N copper(II) nitrate Chemical compound [Cu+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O XTVVROIMIGLXTD-UHFFFAOYSA-N 0.000 description 6
- 229910052878 cordierite Inorganic materials 0.000 description 6
- 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 description 6
- 238000002156 mixing Methods 0.000 description 6
- 239000002002 slurry Substances 0.000 description 6
- 239000000758 substrate Substances 0.000 description 6
- 239000002253 acid Substances 0.000 description 5
- 239000002244 precipitate Substances 0.000 description 5
- 239000000047 product Substances 0.000 description 5
- 239000012495 reaction gas Substances 0.000 description 5
- 238000005406 washing Methods 0.000 description 5
- CSDREXVUYHZDNP-UHFFFAOYSA-N alumanylidynesilicon Chemical compound [Al].[Si] CSDREXVUYHZDNP-UHFFFAOYSA-N 0.000 description 4
- 239000006229 carbon black Substances 0.000 description 4
- 239000011248 coating agent Substances 0.000 description 4
- 238000000576 coating method Methods 0.000 description 4
- 235000019441 ethanol Nutrition 0.000 description 4
- 238000000034 method Methods 0.000 description 4
- RMAQACBXLXPBSY-UHFFFAOYSA-N silicic acid Chemical compound O[Si](O)(O)O RMAQACBXLXPBSY-UHFFFAOYSA-N 0.000 description 4
- 239000012535 impurity Substances 0.000 description 3
- MIVBAHRSNUNMPP-UHFFFAOYSA-N manganese(2+);dinitrate Chemical compound [Mn+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O MIVBAHRSNUNMPP-UHFFFAOYSA-N 0.000 description 3
- 238000004949 mass spectrometry Methods 0.000 description 3
- 238000007254 oxidation reaction Methods 0.000 description 3
- GPNDARIEYHPYAY-UHFFFAOYSA-N palladium(ii) nitrate Chemical compound [Pd+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O GPNDARIEYHPYAY-UHFFFAOYSA-N 0.000 description 3
- VXNYVYJABGOSBX-UHFFFAOYSA-N rhodium(3+);trinitrate Chemical compound [Rh+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VXNYVYJABGOSBX-UHFFFAOYSA-N 0.000 description 3
- 238000002791 soaking Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 2
- 239000007864 aqueous solution Substances 0.000 description 2
- 239000012298 atmosphere Substances 0.000 description 2
- 239000004202 carbamide Substances 0.000 description 2
- 230000003197 catalytic effect Effects 0.000 description 2
- 238000002485 combustion reaction Methods 0.000 description 2
- 238000000354 decomposition reaction Methods 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 239000013618 particulate matter Substances 0.000 description 2
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 1
- 230000010757 Reduction Activity Effects 0.000 description 1
- 238000003916 acid precipitation Methods 0.000 description 1
- 230000002378 acidificating effect Effects 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 238000006555 catalytic reaction Methods 0.000 description 1
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 239000003344 environmental pollutant Substances 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 239000002803 fossil fuel Substances 0.000 description 1
- UQSXHKLRYXJYBZ-UHFFFAOYSA-N iron oxide Inorganic materials [Fe]=O UQSXHKLRYXJYBZ-UHFFFAOYSA-N 0.000 description 1
- MVFCKEFYUDZOCX-UHFFFAOYSA-N iron(2+);dinitrate Chemical compound [Fe+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O MVFCKEFYUDZOCX-UHFFFAOYSA-N 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 231100000719 pollutant Toxicity 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 230000035484 reaction time Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000006722 reduction reaction Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N titanium dioxide Inorganic materials O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- 230000001988 toxicity Effects 0.000 description 1
- 231100000419 toxicity Toxicity 0.000 description 1
- 238000004506 ultrasonic cleaning Methods 0.000 description 1
- 229910052720 vanadium Inorganic materials 0.000 description 1
- LEONUFNNVUYDNQ-UHFFFAOYSA-N vanadium atom Chemical compound [V] LEONUFNNVUYDNQ-UHFFFAOYSA-N 0.000 description 1
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- 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
- B01J29/42—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 iron group metals, noble metals or copper
- B01J29/46—Iron group metals or copper
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
- B01D53/34—Chemical or biological purification of waste gases
- B01D53/92—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
- B01D53/9404—Removing only nitrogen compounds
- B01D53/9409—Nitrogen oxides
- B01D53/9413—Processes characterised by a specific catalyst
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- 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
- B01J29/42—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 iron group metals, noble metals or copper
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- 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
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Abstract
The invention provides a two-stage catalyst for treating tail gas of diesel vehicles, which comprises the following components: catalyst A at the gas inlet end and catalyst B at the gas outlet end; the catalyst A has the general formula: CeO (CeO)2-X/molecular sieve; wherein X is selected from CuO and Fe2O3Or MnO2(ii) a The catalyst B has the general formula: m @ CeO2Molecular sieve; wherein M is selected from Rh, Pt or Pd. Compared with the prior art, the two-stage catalyst provided by the invention is used for treating the tail gas of the diesel vehicle, has high elimination effect and selectivity on nitrogen oxides in a wider temperature range, can eliminate particulate matters to a certain extent, and has an ammonia escape elimination function. And the gas outlet end catalyst B also has the function of a DOC catalyst. The experimental result shows that the two-section catalyst provided by the invention has the temperature of 150-550 ℃ and the high space velocity of 240000h‑1Under the condition, the nitrogen oxide conversion activity is higher than 80%, the stability is good, and the N is excellent at high temperature2Selectivity; and carbon particles in the tail gas can be eliminated at about 450 ℃.
Description
Technical Field
The invention relates to the technical field of catalysts, in particular to a two-section type catalyst for treating tail gas of diesel vehicles and a preparation method thereof.
Background
Nitrogen Oxides (NO)x) Mainly NO and NO2Wherein NO accounts for 95%. Nitrogen oxides are one of the major atmospheric pollutants, and their direct contact with air and water can cause many hazards, such as acid rain, photochemical smog, stratospheric ozone depletion, global climate change, and the like. The nitrogen oxides in the atmosphere mainly come from both mobile sources (motor vehicles) and stationary sources (mainly thermal power plants, industrial combustion plants), among whichGlobal 95% of nitrogen oxides are derived from automotive emissions (49%) and power plant emissions (46%). With the increase of energy consumption and the rapid increase of the number of motor vehicles, a large amount of acidic substances such as nitrogen oxides and the like discharged into the atmosphere after a large amount of fossil fuels are consumed are more and more, and the atmospheric pollution is increasingly serious. Therefore, as global emission limits for nitrogen oxides become more stringent, how to efficiently eliminate nitrogen oxides becomes a worldwide problem.
Currently, there are many methods for eliminating nitrogen oxides, in which ammonia selectively catalyzes the reduction of nitrogen oxides (NH)3SCR), has become one of the most effective methods for eliminating nitrogen oxides due to its high efficiency and relative cost performance. One of the key components of the selective catalytic reduction technology of nitrogen oxides is the catalyst, and the traditional and commercialized catalyst for eliminating nitrogen oxides is mainly V2O5-WO3/TiO2Catalyst capable of exhibiting high NO at 300 ℃ to 400 ℃xAnd (4) removing rate.
However, there are problems with the use of the catalyst in the treatment of diesel exhaust, such as: narrow temperature window, high temperature N2Poor selectivity with N2Formation of O and NH3And TiO, and2the crystal structure can be changed at high temperature, so that the catalytic activity is reduced, and simultaneously, vanadium has toxicity to the environment and low bearable airspeed. The catalyst used for treating automobile exhaust in the prior art is a Pasteur SSZ-13 molecular sieve catalyst, although the temperature window is wider and the catalyst is resistant to high airspeed, the catalyst has low-temperature activity and cannot eliminate particles; and the particulate matters in the tail gas of the diesel vehicle are discharged into the air, so that the diesel vehicle has great harm to people. Therefore, it is an urgent technical problem for those skilled in the art to develop a catalyst which has high removal effect and selectivity for nitrogen oxides in a wider temperature range and can remove particulate matter to some extent.
Disclosure of Invention
In view of the above, the present invention provides a two-stage catalyst for treating diesel exhaust and a preparation method thereof, wherein the two-stage catalyst provided by the present invention has high nitrogen oxide removal effect and selectivity in a wide temperature range, and can remove particulate matter to a certain extent.
The invention provides a two-stage catalyst for treating tail gas of diesel vehicles, which comprises the following components: catalyst A at the gas inlet end and catalyst B at the gas outlet end;
the catalyst A has a general formula shown in formula (I):
CeO2-X/molecular sieve formula (I);
wherein X is selected from CuO and Fe2O3Or MnO2；
The catalyst B has a general formula shown in formula (II):
M@CeO2molecular sieve formula (II);
wherein M is selected from Rh, Pt or Pd.
Preferably, in the formula (I), CeO2And the molar ratio of X to X is (3-19): 1.
preferably, in the formula (I), the molecular sieve is selected from ZSM-5, MCM-56 or BEA;
the CeO2-the mass ratio of X to molecular sieve is 1: (1-10).
Preferably, in the formula (II), the molar ratio of M to CeO2 is 1: (8-32).
Preferably, in the formula (II), the molecular sieve is selected from ZSM-5, MCM-56 or BEA;
the mass ratio of the M @ CeO2 to the molecular sieve is 1: (1-10).
Preferably, the mass ratio of the catalyst A to the catalyst B is (0.5-3): 1.
the invention also provides a preparation method of the two-section catalyst in the technical scheme, which comprises the following steps:
a) carrying out hydrothermal reaction on a cerium source, an X' source and triethylamine in a first solvent to obtain CeO2-X nanoparticles; the X' source is selected from a copper source, an iron source or a manganese source;
b) carrying out coprecipitation reaction on an M' source, a cerium source and ammonia water in a second solvent to obtain M @ CeO2Core-shell structured nanoparticles; the source of M' is selected from a source of rhodium, a source of platinum, or a source of palladium;
c) subjecting the CeO obtained in step a)2-X nanoparticles and M @ CeO obtained in step b)2Loading the core-shell structure nano particles with a molecular sieve respectively to obtain a catalyst A and a catalyst B respectively;
d) arranging a catalyst A at an air inlet end and a catalyst B at an air outlet end to obtain a two-section catalyst for treating the tail gas of the diesel vehicle;
the steps a) and b) are not limited in order.
Preferably, the temperature of the hydrothermal reaction in the step a) is 160-200 ℃ and the time is 20-30 h.
Preferably, the temperature of the coprecipitation reaction in the step b) is 50-70 ℃, and the time is 0.5-1.5 h.
Preferably, the CeO in step c)2-the average particle size of the X nanoparticles is between 3nm and 5 nm; the M @ CeO2The average grain diameter of the core-shell structure nano-particles is 45nm to 55 nm.
The invention provides a two-stage catalyst for treating tail gas of a diesel vehicle, which comprises a catalyst A at an air inlet end and a catalyst B at an air outlet end; the catalyst A has the general formula: CeO (CeO)2-X/molecular sieve; wherein X is selected from CuO and Fe2O3Or MnO2(ii) a The catalyst B has the general formula: m @ CeO2Molecular sieve; wherein M is selected from Rh, Pt or Pd. Compared with the prior art, the two-stage catalyst provided by the invention is used for treating the tail gas of the diesel vehicle, has high elimination effect and selectivity on nitrogen oxides in a wider temperature range, and can eliminate particulate matters to a certain extent. The experimental result shows that the two-section catalyst provided by the invention has the temperature of 150-550 ℃ and the high space velocity of 240000h-1Under the condition, the nitrogen oxide conversion activity is higher than 80%, the stability is good, and the N is excellent at high temperature2Selectivity; and carbon particles in the tail gas can be eliminated at about 450 ℃.
In addition, the two-stage catalyst provided by the invention has the advantages of simple preparation process, mild conditions, low cost, no environmental pollution, urea decomposition and elimination of escaping NH3The function of (1).
Drawings
FIG. 1 shows CeO obtained in example 12-Fe2O3TEM photograph of the nanoparticles;
FIG. 2 shows Rh @ CeO prepared in example 12TEM photograph of core-shell structured nanoparticles;
FIG. 3 shows CeO obtained in example 52-Fe2O3TEM photograph of/MCM-56;
FIG. 4 shows Rh @ CeO prepared in example 52TEM photograph of/MCM-56;
FIG. 5 is a comparison graph of catalytic reduction activities of nitrogen oxides by the two-stage catalysts provided in example 10 and comparative examples 3 to 4.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention provides a two-stage catalyst for treating tail gas of diesel vehicles, which comprises the following components: catalyst A at the gas inlet end and catalyst B at the gas outlet end;
the catalyst A has a general formula shown in formula (I):
CeO2-X/molecular sieve formula (I);
wherein X is selected from CuO and Fe2O3Or MnO2；
The catalyst B has a general formula shown in formula (II):
M@CeO2molecular sieve formula (II);
wherein M is selected from Rh, Pt or Pd.
In the present invention, the two-stage catalyst is used for diesel exhaust treatment by using a reactor such as a tubular fixed bed reactor well known to those skilled in the art. As is well known to those skilled in the art, the two-stage catalyst for performing a catalytic reaction has an inlet end and an outlet end according to a gas flow direction during the reaction, the inlet end contacts a reaction gas first, and the outlet end contacts the reaction gas later, and the present invention is not particularly limited thereto.
In the invention, the two-stage catalyst comprises a catalyst A at the gas inlet end and a catalyst B at the gas outlet end. In the present invention, the catalyst A has a general formula shown in formula (I):
CeO2-X/molecular sieve formula (I);
wherein X is selected from CuO and Fe2O3Or MnO2CuO is preferable. In the present invention, the CeO2X is an active component of the catalyst A, and the molecular sieve is a carrier of the catalyst A. In a preferred embodiment of the present invention, X is CuO, and the catalyst a is CeO2-CuO/molecular sieve; x is Fe2O3The catalyst A is CeO2-Fe2O3Molecular sieve; x is MnO2The catalyst A is CeO2-MnO2Molecular sieve. In the present invention, in the formula (I), CeO2And X is preferably (3-19): 1, more preferably (4-17): 1, more preferably (6 to 13): 1, most preferably (6.7-9.3): 1.
in the present invention, in said formula (I), said molecular sieve is preferably selected from ZSM-5, MCM-56 or BEA, more preferably MCM-56. The source of the molecular sieve is not particularly limited in the present invention, and commercially available or laboratory-derived products of ZSM-5, MCM-56 and BEA described above, which are well known to those skilled in the art, may be used. In a preferred embodiment of the invention, the molecular sieve is ZSM-5, and the silica-alumina ratio of the ZSM-5 is preferably (5-20): 1, more preferably 12: 1. in a preferred embodiment of the invention, the molecular sieve is MCM-56, and the silicon-aluminum ratio of the MCM-56 is preferably (15-30): 1, more preferably 25: 1. in a preferred embodiment of the invention, the molecular sieve is BEA, and the silicon-aluminum ratio of the BEA is preferably (15-25): 1, more preferably 19: 1.
in the present invention, in the formula (I), the CeO2The mass ratio of-X to molecular sieve is preferably 1: (1-10), more preferably 1: 5.
in the present invention, the catalyst B has a general formula shown in formula (II):
M@CeO2molecular sieve formula (II);
wherein M is selected from Rh, Pt or Pd, preferably Pt. In the present invention, the M @ CeO2Is the active component of catalyst B, and the molecular sieve is the carrier of catalyst A. In a preferred embodiment of the present invention, M is Rh, and the catalyst B is Rh @ CeO2Molecular sieve; m is Pt, and the catalyst B is Pt @ CeO2Molecular sieve; m is Pd, and the catalyst B is Pd @ CeO2Molecular sieve. In the present invention, in the formula (II), M and CeO2Is preferably 1: (8-32), more preferably 1: 16.
in the present invention, in said formula (II), said molecular sieve is preferably selected from ZSM-5, MCM-56 or BEA, more preferably MCM-56. The source of the molecular sieve is not particularly limited in the present invention, and commercially available or laboratory-derived products of ZSM-5, MCM-56 and BEA described above, which are well known to those skilled in the art, may be used. In a preferred embodiment of the invention, the molecular sieve is ZSM-5, and the silica-alumina ratio of the ZSM-5 is preferably (5-20): 1, more preferably 12: 1. in a preferred embodiment of the invention, the molecular sieve is MCM-56, and the silicon-aluminum ratio of the MCM-56 is preferably (15-30): 1, more preferably 25: 1. in a preferred embodiment of the invention, the molecular sieve is BEA, and the silicon-aluminum ratio of the BEA is preferably (15-25): 1, more preferably 19: 1.
in the present invention, in the formula (II), the M @ CeO2And the mass ratio of the molecular sieve to the molecular sieve is 1: (1-10), more preferably 1: 5.
in the invention, the mass ratio of the catalyst A to the catalyst B is preferably (0.5-3): 1, more preferably 1: 1.
the invention also provides a preparation method of the two-section catalyst in the technical scheme, which comprises the following steps:
a) carrying out hydrothermal reaction on a cerium source, an X' source and triethylamine in a first solvent to obtain CeO2-X nanoparticles; the X' source is selected from a copper source, an iron source or a manganese source;
b) carrying out coprecipitation reaction on an M' source, a cerium source and ammonia water in a second solvent to obtain M @ CeO2Core-shell structured nanoparticles; the source of M' is selected from a source of rhodium, a source of platinum, or a source of palladium;
c) subjecting the CeO obtained in step a)2-X nanoparticles and M @ CeO obtained in step b)2Loading the core-shell structure nano particles with a molecular sieve respectively to obtain a catalyst A and a catalyst B respectively;
d) arranging a catalyst A at an air inlet end and a catalyst B at an air outlet end to obtain a two-section catalyst for treating the tail gas of the diesel vehicle;
the steps a) and b) are not limited in order.
Firstly, cerium source, X' source and triethylamine are subjected to hydrothermal reaction in a first solvent to obtain CeO2-X nanoparticles. In the present invention, the cerium source is preferably cerium nitrate; the X' source is selected from a copper source, an iron source or a manganese source, wherein the copper source is preferably copper nitrate, the iron source is preferably ferric nitrate, and the manganese source is preferably a manganese nitrate solution with the mass fraction of 50%; the first solvent is preferably an ethanol solution of polyvinylpyrrolidone, and the mass concentration of the ethanol solution of polyvinylpyrrolidone in the first solvent is preferably 10 g/L-30 g/L. The present invention is not particularly limited with respect to the sources of the cerium source, the X' source, the triethylamine and the first solvent, and commercially available products of the above-mentioned cerium nitrate, copper nitrate, iron nitrate, a 50% by mass manganese nitrate solution, polyvinylpyrrolidone and ethanol, which are well known to those skilled in the art, are used.
The present invention is not particularly limited in the manner of the hydrothermal reaction, and may be carried out by a method well known to those skilled in the art. In the invention, the hydrothermal reaction temperature is preferably 160-200 ℃, and more preferably 180 ℃; the hydrothermal reaction time is preferably 20 to 30 hours, and more preferably 24 hours.
In the present invention, CeO is obtained2The average particle diameter of the-X nanoparticles is preferably 3nm to 5 nm.
Meanwhile, the M' source, the cerium source and ammonia water are subjected to coprecipitation reaction in a second solvent to obtain M @ CeO2Core-shell structured nanoparticles.In the invention, the M' source is selected from a rhodium source, a platinum source or a palladium source, wherein the rhodium source is preferably a rhodium nitrate solution, the platinum source is preferably a chloroplatinic acid solution, and the palladium source is preferably a palladium nitrate solution; the cerium source is preferably a cerium nitrate solution; the ammonia water is preferably ammonia water with the mass concentration of 25%; the second solvent is preferably an aqueous solution of potassium bromide or an aqueous solution of potassium iodide, and the mass concentration of the second solvent is preferably 0.3g/L to 0.4g/L, and more preferably 0.375 g/L. The sources of the M' source, the cerium source, the aqueous ammonia and the second solvent are not particularly limited in the present invention, and commercially available products of the above rhodium nitrate solution, chloroplatinic acid solution, palladium nitrate solution, cerium nitrate solution, aqueous ammonia having a mass concentration of 25%, potassium bromide and potassium iodide, which are well known to those skilled in the art, are used.
The present invention is not particularly limited in the manner of the coprecipitation reaction, and may be carried out by a method well known to those skilled in the art. In the present invention, the temperature of the coprecipitation reaction is preferably 50 to 70 ℃, and more preferably 60 ℃; the time of the coprecipitation reaction is preferably 0.5h to 1.5h, and more preferably 1 h.
In the present invention, M @ CeO was obtained2The average particle diameter of the core-shell structured nanoparticle is preferably 45nm to 55nm, and more preferably 50 nm.
To obtain the CeO2-X nanoparticles and M @ CeO2After core-shell structured nanoparticles are formed, the CeO is obtained2-X nanoparticles and resulting M @ CeO2And respectively loading the core-shell structure nano particles with a molecular sieve to respectively obtain a catalyst A and a catalyst B. In the present invention, the molecular sieve is the same as that described in the above technical scheme, and is not described herein again. The loading mode of the present invention is not particularly limited, and the technical scheme of loading nanoparticles to a molecular sieve, which is well known to those skilled in the art, may be adopted, and specifically, the following is preferred:
dispersing the nano particles in deionized water or ethanol, adding a molecular sieve after uniform dispersion, performing ultrasonic treatment for 0.5h, stirring for 4h to make the nano particles uniform, evaporating to dryness, drying overnight, and calcining to obtain the nano particle loaded molecular sieve. In the present invention, the temperature of the calcination is preferably 400 to 600 ℃, more preferably 500 ℃; the calcination time is preferably 1 to 8 hours, more preferably 2 hours.
In the present invention, CeO is added2-X nanoparticles and M @ CeO2After the core-shell structured nanoparticles are respectively loaded with the molecular sieve, the catalyst a and the catalyst B respectively obtained are the same as those described in the above technical scheme, and are not described herein again.
After the catalyst A and the catalyst B are respectively obtained, the catalyst A is arranged at the air inlet end, and the catalyst B is arranged at the air outlet end, so that the two-stage catalyst for treating the tail gas of the diesel vehicle is obtained. The invention has no special limitation on the arrangement mode of the catalyst A/catalyst B in the two-section catalyst, and preferably, the catalyst A/catalyst B is tableted and ground, and the size of particles of 40-60 meshes is screened for direct use, or the catalyst A/catalyst B is coated on a substrate to obtain the coated catalyst A/coated catalyst B for reuse. In the present invention, the coated substrate of the coated catalyst a/coated catalyst B is preferably a honeycomb ceramic substrate or a metal honeycomb carrier.
The two-section catalyst can be used for purifying nitrogen oxides in tail gas of mobile sources or fixed combustion devices including various motor vehicle engines and coal-fired power plants. When in use, the catalyst is placed in a tail gas pipeline, a reducing agent is sprayed from the gas inlet end of the two-section type catalyst to be mixed with tail gas, wherein NH3The ratio of the amount to be counted to NO is 0.8-1.2.
The invention provides a two-stage catalyst for treating tail gas of diesel vehicles, which comprises the following components: catalyst A at the gas inlet end and catalyst B at the gas outlet end; the catalyst A has the general formula: CeO (CeO)2-X/molecular sieve; wherein X is selected from CuO and Fe2O3Or MnO2(ii) a The catalyst B has the general formula: m @ CeO2Molecular sieve; wherein M is selected from Rh, Pt or Pd. Compared with the prior art, the two-stage catalyst provided by the invention is used for treating the tail gas of the diesel vehicle, has high elimination effect and selectivity on nitrogen oxides in a wider temperature range, and can eliminate particulate matters to a certain extent. The experimental result shows that the two-section catalyst provided by the invention has the temperature of 150-550 ℃ and the high space velocity of 240000h-1With nitrogen oxidation higher than 80% under the conditionConversion activity, good stability and excellent N at high temperature2Selectivity; and carbon particles in the tail gas can be eliminated at about 450 ℃.
In addition, the two-stage catalyst provided by the invention has the advantages of simple preparation process, mild conditions, low cost, no environmental pollution, urea decomposition and elimination of escaping NH3The function of (1).
In addition, the catalyst in the two-stage catalyst provided by the invention is easy to coat on substrates such as honeycomb ceramics or metal honeycomb carriers to obtain a coated catalyst, and is expected to be directly used for purifying the tail gas of the diesel vehicle so as to meet the stricter emission standard of the sixth nation.
To further illustrate the present invention, the following examples are provided for illustration. The raw materials used in the following examples of the present invention are all commercially available products.
Example 1
(1) Preparation of CeO2-Fe2O3Nanoparticle:
weighing 5.4g of polyvinylpyrrolidone (PVP-K30) and dissolving in 360mL of absolute ethyl alcohol; adding 0.7422g of cerium nitrate and 0.0218g of ferric nitrate into the solution after PVP is completely dissolved, dropwise adding 1.82g of triethylamine after stirring until PVP is completely dissolved, stirring for 10min, transferring into a reaction kettle, carrying out hydrothermal reaction at 180 ℃ for 24h, and taking out the reaction product to a constant volume (0.0008g/mL) for later use.
The CeO2-Fe2O3TEM photograph of nanoparticles is shown in FIG. 1, and it is clear from FIG. 1 that CeO2-Fe2O3The average particle diameter of the nanoparticles is 3nm to 5 nm.
(2) Preparation of Rh @ CeO2Core-shell structured nanoparticles:
adding 7.5mg of potassium bromide into a beaker filled with 20mL of deionized water, stirring and dissolving in a water bath at 60 ℃, then sequentially adding 0.417mL of 0.03M rhodium nitrate solution and 2mL of 0.1M cerium nitrate solution, dropwise adding 0.05mL of 25% ammonia water diluted by 5mL of deionized water, finally stirring and keeping for 1h at 60 ℃, centrifuging to obtain a precipitate, washing with water for multiple times, and drying at 100 ℃ for later use.
Rh @ CeO2Core-shell structureTEM photograph of nanoparticles is shown in FIG. 2, and from FIG. 2, Rh @ CeO2The average grain diameter of the core-shell structure nano particles is about 50 nm.
(3) Preparation of CeO2-Fe2O3/ZSM-5：
Taking the CeO with constant volume in the step (1)2-Fe2O3250mL of nanoparticle sol solution was added with 1g of molecular sieve ZSM-5(n (SiO)2)/n(Al2O3) 12), stirring for 4h after ultrasonic treatment for 0.5h to make the mixture uniform, stirring and evaporating at 100 ℃, drying overnight at 100 ℃, heating to 500 ℃ at 1 ℃/min in air and keeping for 2h to obtain CeO2-Fe2O3ZSM-5, i.e. catalyst A; finally, the catalyst A is tabletted and ground, and the catalyst A is screened to obtain particles with the size of 40-60 meshes for later use.
(4) Preparation of Rh @ CeO2/ZSM-5：
Weighing 0.2g of Rh @ CeO in the step (2)2Dispersing the core-shell structure nano particles in 20mL of deionized water, and adding 1g of molecular sieve ZSM-5(n (SiO)2)/n(Al2O3) 12), stirring for 4h after ultrasonic treatment for 0.5h to make the mixture uniform, heating at 80 ℃, stirring and evaporating to dryness, drying the obtained sample at 100 ℃ overnight, heating to 500 ℃ at 1 ℃/min in air and keeping for 2h to obtain Rh @ CeO2ZSM-5, catalyst B; finally, tabletting and grinding the catalyst B, and screening to obtain particles of 40-60 meshes for later use.
(5) And (3) arranging 25mg of the catalyst A at the gas inlet end of the tubular fixed bed reactor, and arranging 25mg of the catalyst B at the gas outlet end of the tubular fixed bed reactor to obtain the two-stage catalyst for treating the tail gas of the diesel vehicle.
Example 2
(1) Preparation of CeO2-Fe2O3Nanoparticle:
weighing 5.4g of polyvinylpyrrolidone (PVP-K30) and dissolving in 360mL of absolute ethyl alcohol; adding 0.4661g of cerium nitrate and 0.0186g of ferric nitrate into the solution after PVP is completely dissolved, dropwise adding 1.22g of triethylamine after stirring until PVP is completely dissolved, stirring for 10min, transferring into a reaction kettle, carrying out hydrothermal reaction at 180 ℃ for 24h, and taking out the reaction product to a constant volume (0.0008g/mL) for later use.
(2) Preparation of Rh @ CeO2Core-shell junctionStructuring the nanoparticles: the same as in example 1.
(3) Preparation of CeO2-Fe2O3ZSM-5: the same as in example 1.
(4) Preparation of Rh @ CeO2ZSM-5: the same as in example 1.
(5) And (3) arranging 25mg of the catalyst A at the gas inlet end of the tubular fixed bed reactor, and arranging 25mg of the catalyst B at the gas outlet end of the tubular fixed bed reactor to obtain the two-stage catalyst for treating the tail gas of the diesel vehicle.
Example 3
(1) Preparation of CeO2-Fe2O3Nanoparticle:
weighing 3.6g of polyvinylpyrrolidone (PVP-K30) and dissolving in 240mL of absolute ethyl alcohol; adding 0.4687g of cerium nitrate and 0.0290g of ferric nitrate into the solution after PVP is completely dissolved, dropwise adding 1.22g of triethylamine after stirring until PVP is completely dissolved, stirring for 10min, transferring into a reaction kettle, carrying out hydrothermal reaction at 180 ℃ for 24h, and taking out the reaction product to a constant volume (0.0008g/mL) for later use.
(2) Preparation of Rh @ CeO2Core-shell structured nanoparticles: the same as in example 1.
(3) Preparation of CeO2-Fe2O3ZSM-5: the same as in example 1.
(4) Preparation of Rh @ CeO2ZSM-5: the same as in example 1.
(5) And (3) arranging 25mg of the catalyst A at the gas inlet end of the tubular fixed bed reactor, and arranging 25mg of the catalyst B at the gas outlet end of the tubular fixed bed reactor to obtain the two-stage catalyst for treating the tail gas of the diesel vehicle.
Example 4
(1) Preparation of CeO2-Fe2O3Nanoparticle:
weighing 3.6g of polyvinylpyrrolidone (PVP-K30) and dissolving in 240mL of absolute ethyl alcohol; adding 0.4166g of cerium nitrate and 0.0580g of ferric nitrate into the solution after PVP is completely dissolved, dropwise adding 1.22g of triethylamine after stirring until PVP is completely dissolved, stirring for 10min, transferring into a reaction kettle, carrying out hydrothermal reaction at 180 ℃ for 24h, and taking out the reaction product to a constant volume (0.0008g/mL) for later use.
(2) Preparation of Rh @ CeO2Core-shell structure nanoparticleA step of: the same as in example 1.
(3) Preparation of CeO2-Fe2O3ZSM-5: the same as in example 1.
(4) Preparation of Rh @ CeO2ZSM-5: the same as in example 1.
(5) And (3) arranging 25mg of the catalyst A at the gas inlet end of the tubular fixed bed reactor, and arranging 25mg of the catalyst B at the gas outlet end of the tubular fixed bed reactor to obtain the two-stage catalyst for treating the tail gas of the diesel vehicle.
Example 5
(1) Preparation of CeO2-Fe2O3Nanoparticle: the same as in example 4.
(2) Preparation of Rh @ CeO2Core-shell structured nanoparticles: the same as in example 1.
(3) Preparation of CeO2-FeO/MCM-56：
Taking the CeO with constant volume in the step (1)2-Fe2O3130mL of the nanoparticle sol solution was added with 0.5g of molecular sieve MCM-56(n (SiO)2)/n(Al2O3) 25), stirring for 4h after ultrasonic treatment for 0.5h to make the mixture uniform, stirring and evaporating at 100 ℃, drying overnight at 100 ℃, heating to 500 ℃ at 1 ℃/min in air and keeping for 2h to obtain CeO2-Fe2O3/MCM-56, catalyst A; the CeO2-Fe2O3TEM photograph of/MCM-56 is shown in FIG. 3; finally, the catalyst A is tabletted and ground, and the catalyst A is screened to obtain particles with the size of 40-60 meshes for later use.
(4) Preparation of Rh @ CeO2/MCM-56：
Weighing 0.2g of Rh @ CeO in the step (2)2Dispersing the core-shell structure nano particles in 20mL of deionized water, and adding 1g of molecular sieve MCM-56(n (SiO)2)/n(Al2O3) 25), stirring for 4h after ultrasonic treatment for 0.5h to make the mixture uniform, heating at 80 ℃, stirring and evaporating to dryness, drying the obtained sample at 100 ℃ overnight, heating to 500 ℃ at 1 ℃/min in air and keeping for 2h to obtain Rh @ CeO2/MCM-56, catalyst B; rh @ CeO2TEM photograph of/MCM-56 is shown in FIG. 4; finally, tabletting and grinding the catalyst B, and screening to obtain particles of 40-60 meshes for later use.
(5) And (3) arranging 25mg of the catalyst A at the gas inlet end of the tubular fixed bed reactor, and arranging 25mg of the catalyst B at the gas outlet end of the tubular fixed bed reactor to obtain the two-stage catalyst for treating the tail gas of the diesel vehicle.
Example 6
(1) Preparation of CeO2-Fe2O3Nanoparticle: the same as in example 4.
(2) Preparation of Rh @ CeO2Core-shell structured nanoparticles: the same as in example 1.
(3) Preparation of CeO2-Fe2O3/BEA：
Taking the CeO with constant volume in the step (1)2-Fe2O3130mL of nanoparticle sol solution, 0.51g of molecular sieve BEA (n (SiO)2)/n(Al2O3) 19) and ultrasonically treating for 0.5h, stirring for 4h to be uniform, stirring and evaporating at 100 ℃, drying at 100 ℃ overnight, heating to 500 ℃ at the speed of 1 ℃/min in air, and keeping for 2h to obtain CeO2-Fe2O3/BEA, i.e.catalyst A; finally, the catalyst A is tabletted and ground, and the catalyst A is screened to obtain particles with the size of 40-60 meshes for later use.
(4) Preparation of Rh @ CeO2/MCM-56：
Weighing 0.2g of Rh @ CeO in the step (2)2Dispersing the core-shell structure nano particles in 20mL of deionized water, and adding 1g of molecular sieve BEA (n (SiO)2)/n(Al2O3) 19) and ultrasonically treating for 0.5h, stirring for 4h to ensure that the mixture is uniform, heating at 80 ℃, stirring and evaporating to dryness, drying the obtained sample at 100 ℃ overnight, heating to 500 ℃ at 1 ℃/min in air, and keeping for 2h to obtain Rh @ CeO2/BEA, i.e.catalyst B; finally, tabletting and grinding the catalyst B, and screening to obtain particles of 40-60 meshes for later use.
(5) And (3) arranging 25mg of the catalyst A at the gas inlet end of the tubular fixed bed reactor, and arranging 25mg of the catalyst B at the gas outlet end of the tubular fixed bed reactor to obtain the two-stage catalyst for treating the tail gas of the diesel vehicle.
Example 7
(1) Preparation of CeO2-CuO nanoparticles:
weighing 5.4g of polyvinylpyrrolidone (PVP-K30) and dissolving in 360mL of absolute ethyl alcohol; adding 0.7422g of cerium nitrate and 0.0217g of copper nitrate into the solution after PVP is completely dissolved, dropwise adding 1.82g of triethylamine after stirring until PVP is completely dissolved, stirring for 10min, transferring into a reaction kettle, carrying out hydrothermal reaction at 180 ℃ for 24h, and taking out the reaction product to a constant volume (0.0008g/mL) for later use.
(2) Preparation of Pt @ CeO2Core-shell structured nanoparticles:
adding 7.5mg of potassium iodide into a beaker filled with 20mL of deionized water, stirring and dissolving in a water bath at 60 ℃, then sequentially adding 0.417mL of 0.03M chloroplatinic acid solution and 2mL of 0.1M cerous nitrate solution, dropwise adding 0.05mL of 25% ammonia water diluted by 5mL of deionized water, finally stirring and keeping for 1h at 60 ℃, centrifuging to obtain a precipitate, washing with water for multiple times, and drying at 100 ℃ for later use.
(3) Preparation of CeO2-CuO/ZSM-5：
Taking the CeO with constant volume in the step (1)2250mL of-CuO nanoparticle sol solution, 1g of molecular sieve ZSM-5(n (SiO)2)/n(Al2O3) 12), stirring for 4h after ultrasonic treatment for 0.5h to make the mixture uniform, stirring and evaporating at 100 ℃, drying overnight at 100 ℃, heating to 500 ℃ at 1 ℃/min in air and keeping for 2h to obtain CeO2-CuO/ZSM-5, catalyst a; finally, the catalyst A is tabletted and ground, and the catalyst A is screened to obtain particles with the size of 40-60 meshes for later use.
(4) Preparation of Pt @ CeO2/ZSM-5：
Weighing 0.2g of Pt @ CeO in the step (2)2Dispersing the core-shell structure nano particles in 20mL of deionized water, and adding 1g of molecular sieve ZSM-5(n (SiO)2)/n(Al2O3) 24), ultrasonically treating for 0.5h, stirring for 4h to ensure that the mixture is uniform, heating at 80 ℃, stirring and evaporating to dryness, drying the obtained sample at 100 ℃ overnight, heating to 500 ℃ at 1 ℃/min in air, and keeping for 2h to obtain Pt @ CeO2ZSM-5, catalyst B; finally, tabletting and grinding the catalyst B, and screening to obtain particles of 40-60 meshes for later use.
(5) And (3) arranging 25mg of the catalyst A at the gas inlet end of the tubular fixed bed reactor, and arranging 25mg of the catalyst B at the gas outlet end of the tubular fixed bed reactor to obtain the two-stage catalyst for treating the tail gas of the diesel vehicle.
Example 8
(1) Preparation of CeO2-CuO sodiumRice grains: the same as in example 7.
(2) Preparation of Pt @ CeO2Core-shell structured nanoparticles: the same as in example 7.
(3) Preparation of CeO2-CuO/MCM-56：
Taking the CeO with constant volume in the step (1)2250mL of-CuO nanoparticle sol solution, 1g of molecular sieve MCM-56(n (SiO)2)/n(Al2O3) 25), stirring for 4h after ultrasonic treatment for 0.5h to make the mixture uniform, stirring and evaporating at 100 ℃, drying overnight at 100 ℃, heating to 500 ℃ at 1 ℃/min in air and keeping for 2h to obtain CeO2-CuO/MCM-56, catalyst a; finally, the catalyst A is tabletted and ground, and the catalyst A is screened to obtain particles with the size of 40-60 meshes for later use.
(4) Preparation of Pt @ CeO2/MCM-56：
Weighing 0.2g of Pt @ CeO in the step (2)2Dispersing the core-shell structure nano particles in 20mL of deionized water, and adding 1g of molecular sieve MCM-56(n (SiO)2)/n(Al2O3) 25), stirring for 4h after ultrasonic treatment for 0.5h to make the mixture uniform, heating at 80 ℃, stirring and evaporating to dryness, drying the obtained sample at 100 ℃ overnight, heating to 500 ℃ at 1 ℃/min in air and keeping for 2h to obtain Pt @ CeO2/MCM-56, catalyst B; finally, tabletting and grinding the catalyst B, and screening to obtain particles of 40-60 meshes for later use.
(5) And (3) arranging 25mg of the catalyst A at the gas inlet end of the tubular fixed bed reactor, and arranging 25mg of the catalyst B at the gas outlet end of the tubular fixed bed reactor to obtain the two-stage catalyst for treating the tail gas of the diesel vehicle.
Example 9
(1) Preparation of CeO2-CuO nanoparticles:
weighing 3.6g of polyvinylpyrrolidone (PVP-K30) and dissolving in 240mL of absolute ethyl alcohol; adding 0.4661g of cerium nitrate and 0.0193g of copper nitrate into the solution after PVP is completely dissolved, dropwise adding 1.22g of triethylamine after stirring until PVP is completely dissolved, stirring for 10min, transferring into a reaction kettle, carrying out hydrothermal reaction at 180 ℃ for 24h, and taking out the solution with constant volume (0.0008g/mL) for later use after the reaction is finished.
(2) Preparation of Pt @ CeO2Core-shell structured nanoparticles: the same as in example 7.
(3) Preparation of CeO2-CuO/MCM-56：
Taking the CeO with constant volume in the step (1)2125.6mL of-CuO nanoparticle sol solution, 0.5g of molecular sieve MCM-56(n (SiO)2)/n(Al2O3) 25), stirring for 4h after ultrasonic treatment for 0.5h to make the mixture uniform, stirring and evaporating at 100 ℃, drying overnight at 100 ℃, heating to 500 ℃ at 1 ℃/min in air and keeping for 2h to obtain CeO2-CuO/MCM-56, catalyst a; finally, the catalyst A is tabletted and ground, and the catalyst A is screened to obtain particles with the size of 40-60 meshes for later use.
(4) Preparation of Pt @ CeO2[ MCM-56: the same as in example 8.
(5) And (3) arranging 25mg of the catalyst A at the gas inlet end of the tubular fixed bed reactor, and arranging 25mg of the catalyst B at the gas outlet end of the tubular fixed bed reactor to obtain the two-stage catalyst for treating the tail gas of the diesel vehicle.
Example 10
(1) Preparation of CeO2-CuO nanoparticles:
weighing 3.6g of polyvinylpyrrolidone (PVP-K30) and dissolving in 240mL of absolute ethyl alcohol; adding 0.4687g of cerium nitrate and 0.0290g of copper nitrate into the solution after PVP is completely dissolved, dropwise adding 1.22g of triethylamine after stirring until PVP is completely dissolved, stirring for 10min, transferring into a reaction kettle, carrying out hydrothermal reaction at 180 ℃ for 24h, and taking out the reaction product with constant volume (0.0008g/mL) for later use.
(2) Preparation of Pt @ CeO2Core-shell structured nanoparticles: the same as in example 7.
(3) Preparation of CeO2-CuO/MCM-56：
Taking the CeO with constant volume in the step (1)2123mL of-CuO nanoparticle sol solution, 0.5g of molecular sieve MCM-56(n (SiO)2)/n(Al2O3) 25), stirring for 4h after ultrasonic treatment for 0.5h to make the mixture uniform, stirring and evaporating at 100 ℃, drying overnight at 100 ℃, heating to 500 ℃ at 1 ℃/min in air and keeping for 2h to obtain CeO2-CuO/MCM-56, catalyst a; finally, the catalyst A is tabletted and ground, and the catalyst A is screened to obtain particles with the size of 40-60 meshes for later use.
(4) Preparation of Pt @ CeO2[ MCM-56: the same as in example 8.
(5) And (3) arranging 25mg of the catalyst A at the gas inlet end of the tubular fixed bed reactor, and arranging 25mg of the catalyst B at the gas outlet end of the tubular fixed bed reactor to obtain the two-stage catalyst for treating the tail gas of the diesel vehicle.
Example 11
(1) Preparation of CeO2-CuO nanoparticles:
weighing 3.6g of polyvinylpyrrolidone (PVP-K30) and dissolving in 240mL of absolute ethyl alcohol; adding 0.4166g of cerium nitrate and 0.0580g of copper nitrate into the solution after PVP is completely dissolved, dropwise adding 1.22g of triethylamine after stirring until PVP is completely dissolved, stirring for 10min, transferring into a reaction kettle, carrying out hydrothermal reaction at 180 ℃ for 24h, and taking out the solution with constant volume (0.0008g/mL) for later use after the reaction is finished.
(2) Preparation of Pt @ CeO2Core-shell structured nanoparticles: the same as in example 7.
(3) Preparation of CeO2-CuO/MCM-56：
Taking the CeO with constant volume in the step (1)2130mL of-CuO nanoparticle sol solution, 0.5g of molecular sieve MCM-56(n (SiO)2)/n(Al2O3) 25), stirring for 4h after ultrasonic treatment for 0.5h to make the mixture uniform, stirring and evaporating at 100 ℃, drying overnight at 100 ℃, heating to 500 ℃ at 1 ℃/min in air and keeping for 2h to obtain CeO2-CuO/MCM-56, catalyst a; finally, the catalyst A is tabletted and ground, and the catalyst A is screened to obtain particles with the size of 40-60 meshes for later use.
(4) Preparation of Pt @ CeO2[ MCM-56: the same as in example 8.
(5) And (3) arranging 25mg of the catalyst A at the gas inlet end of the tubular fixed bed reactor, and arranging 25mg of the catalyst B at the gas outlet end of the tubular fixed bed reactor to obtain the two-stage catalyst for treating the tail gas of the diesel vehicle.
Example 12
(1) Preparation of CeO2-CuO nanoparticles: the same as in example 10.
(2) Preparation of Pt @ CeO2Core-shell structured nanoparticles:
adding 7.5mg of potassium iodide into a beaker filled with 20mL of deionized water, stirring and dissolving in a water bath at 60 ℃, then sequentially adding 0.417mL of 0.03M chloroplatinic acid solution and 4mL of 0.1M cerous nitrate solution, dropwise adding 0.05mL of 25% ammonia water diluted by 5mL of deionized water, finally stirring and keeping for 1h at 60 ℃, centrifuging to obtain a precipitate, washing with water for multiple times, and drying at 100 ℃ for later use.
(3) Preparation of CeO2-CuO/MCM-56: the same as in example 10.
(4) Preparation of Pt @ CeO2[ MCM-56: the same as in example 8.
(5) And (3) arranging 25mg of the catalyst A at the gas inlet end of the tubular fixed bed reactor, and arranging 25mg of the catalyst B at the gas outlet end of the tubular fixed bed reactor to obtain the two-stage catalyst for treating the tail gas of the diesel vehicle.
Example 13
(1) Preparation of CeO2-CuO nanoparticles: the same as in example 10.
(2) Preparation of Pt @ CeO2Core-shell structured nanoparticles:
adding 7.5mg of potassium iodide into a beaker filled with 20mL of deionized water, stirring and dissolving in a water bath at 60 ℃, sequentially adding 0.8.34mL of a 0.03M chloroplatinic acid solution and 2mL of a 0.1M cerous nitrate solution, dropwise adding 0.05mL of 25% ammonia water diluted by 5mL of deionized water, stirring and keeping for 1h at 60 ℃, centrifuging to obtain a precipitate, washing with water for multiple times, and drying at 100 ℃ for later use.
(3) Preparation of CeO2-CuO/MCM-56: the same as in example 10.
(4) Preparation of Pt @ CeO2[ MCM-56: the same as in example 8.
(5) And (3) arranging 25mg of the catalyst A at the gas inlet end of the tubular fixed bed reactor, and arranging 25mg of the catalyst B at the gas outlet end of the tubular fixed bed reactor to obtain the two-stage catalyst for treating the tail gas of the diesel vehicle.
Example 14
(1) Preparation of CeO2-CuO nanoparticles: the same as in example 10.
(2) Preparation of Pt @ CeO2Core-shell structured nanoparticles: the same as in example 7.
(3) Preparation of CeO2-CuO/BEA：
Taking the CeO with constant volume in the step (1)2130mL of-CuO nanoparticle sol solution, 0.5g of molecular sieve BEA (n (SiO)2)/n(Al2O3) 19), ultrasonic treating for 0.5h, stirring for 4h to homogenize, stirring at 100 deg.C, evaporating to dryness, and heating at 100 deg.CDrying overnight, heating to 500 deg.C at 1 deg.C/min in air, and maintaining for 2 hr to obtain CeO2-CuO/BEA, catalyst a; finally, the catalyst A is tabletted and ground, and the catalyst A is screened to obtain particles with the size of 40-60 meshes for later use.
(4) Preparation of Pt @ CeO2/BEA：
Weighing 0.2g of Pt @ CeO in the step (2)2Dispersing the core-shell structure nano particles in 20mL of deionized water, and adding 1g of molecular sieve BEA (n (SiO)2)/n(Al2O3) 19) and ultrasonically treating for 0.5h, stirring for 4h to ensure the mixture to be uniform, heating at 80 ℃, stirring and evaporating to dryness, drying the obtained sample at 100 ℃ overnight, heating to 500 ℃ at 1 ℃/min in air, and keeping for 2h to obtain Pt @ CeO2/BEA, i.e.catalyst B; finally, tabletting and grinding the catalyst B, and screening to obtain particles of 40-60 meshes for later use.
(5) And (3) arranging 25mg of the catalyst A at the gas inlet end of the tubular fixed bed reactor, and arranging 25mg of the catalyst B at the gas outlet end of the tubular fixed bed reactor to obtain the two-stage catalyst for treating the tail gas of the diesel vehicle.
Example 15
(1) Preparation of CeO2-Fe2O3Nanoparticle: the same as in example 4.
(2) Preparation of Pd @ CeO2Core-shell structured nanoparticles:
adding 7.5mg of potassium bromide into a beaker filled with 20mL of deionized water, stirring and dissolving in a water bath at 60 ℃, then sequentially adding 0.417mL of 0.03M palladium nitrate solution and 2mL of 0.1M cerium nitrate solution, dropwise adding 0.05mL of 25% ammonia water diluted by 5mL of deionized water, finally stirring and keeping for 1h at 60 ℃, centrifuging to obtain a precipitate, washing with water for multiple times, and drying at 100 ℃ for later use.
(3) Preparation of CeO2-Fe2O3ZSM-5: the same as in example 4.
(4) Preparation of Pd @ CeO2/ZSM-5：
Weighing 0.2g of Pd @ CeO in the step (2)2Dispersing the core-shell structure nano particles in 20mL of deionized water, and adding 1g of molecular sieve ZSM-5(n (SiO)2)/n(Al2O3) 12), stirring for 4h after ultrasonic treatment for 0.5h to make the mixture uniform, heating at 80 ℃, stirring and evaporating to dryness to obtain a sampleDrying at 100 ℃ overnight, heating to 500 ℃ at 1 ℃/min in the air and keeping for 2h to obtain Pd @ CeO2ZSM-5, catalyst B; finally, tabletting and grinding the catalyst B, and screening to obtain particles of 40-60 meshes for later use.
(5) And (3) arranging 25mg of the catalyst A at the gas inlet end of the tubular fixed bed reactor, and arranging 25mg of the catalyst B at the gas outlet end of the tubular fixed bed reactor to obtain the two-stage catalyst for treating the tail gas of the diesel vehicle.
Example 16
(1) Preparation of CeO2-Fe2O3Nanoparticle: the same as in example 15.
(2) Preparation of Pd @ CeO2Core-shell structured nanoparticles: the same as in example 15.
(3) Preparation of CeO2-Fe2O3[ MCM-56: the same as in example 5.
(4) Preparation of Pd @ CeO2/MCM-56：
Weighing 0.2g of Pd @ CeO in the step (2)2Dispersing the core-shell structure nano particles in 20mL of deionized water, and adding 1g of molecular sieve MCM-56(n (SiO)2)/n(Al2O3) 25), stirring for 4h after ultrasonic treatment for 0.5h to ensure that the mixture is uniform, heating at 80 ℃, stirring and evaporating to dryness, drying the obtained sample at 100 ℃ overnight, heating to 500 ℃ at 1 ℃/min in air, and keeping for 2h to obtain Pd @ CeO2/MCM-56, catalyst B; finally, tabletting and grinding the catalyst B, and screening to obtain particles of 40-60 meshes for later use.
(5) And (3) arranging 25mg of the catalyst A at the gas inlet end of the tubular fixed bed reactor, and arranging 25mg of the catalyst B at the gas outlet end of the tubular fixed bed reactor to obtain the two-stage catalyst for treating the tail gas of the diesel vehicle.
Example 17
(1) Preparation of CeO2-Fe2O3Nanoparticle: the same as in example 15.
(2) Preparation of Pd @ CeO2Core-shell structured nanoparticles: the same as in example 15.
(3) Preparation of CeO2-Fe2O3The ratio of/BEA: the same as in example 6.
(4) Preparation of Pd @ CeO2/BEA：
Weighing 0.2g of Pd @ CeO in the step (2)2Dispersing the core-shell structure nano particles in 20mL of deionized water, and adding 1g of molecular sieve BEA (n (SiO)2)/n(Al2O3) 19) and ultrasonically treating for 0.5h, stirring for 4h to ensure the mixture to be uniform, heating at 80 ℃, stirring and evaporating to dryness, drying the obtained sample at 100 ℃ overnight, heating to 500 ℃ at 1 ℃/min in air, and keeping for 2h to obtain Pd @ CeO2/BEA, i.e.catalyst B; finally, tabletting and grinding the catalyst B, and screening to obtain particles of 40-60 meshes for later use.
(5) And (3) arranging 25mg of the catalyst A at the gas inlet end of the tubular fixed bed reactor, and arranging 25mg of the catalyst B at the gas outlet end of the tubular fixed bed reactor to obtain the two-stage catalyst for treating the tail gas of the diesel vehicle.
Example 18
(1) Preparation of CeO2-MnO2Nanoparticle:
weighing 3.6g of polyvinylpyrrolidone (PVP-K30) and dissolving in 240mL of absolute ethyl alcohol; adding 0.4687g of cerium nitrate and 0.04294g of a 50% manganese nitrate solution into the solution after PVP is completely dissolved, dropwise adding 1.22g of triethylamine after stirring until PVP is completely dissolved, stirring for 10min, transferring the mixture into a reaction kettle, carrying out hydrothermal reaction at 180 ℃ for 24h, and taking out the mixture to a constant volume (0.0008g/mL) for later use after the reaction is finished.
(2) Preparation of Pt @ CeO2Core-shell structured nanoparticles: the same as in example 7.
(3) Preparation of CeO2-MnO2/ZSM-5：
Taking the CeO with constant volume in the step (1)2-MnO2130mL of nanoparticle sol solution, 0.5g of molecular sieve ZSM-5(n (SiO)2)/n(Al2O3) 12), stirring for 4h after ultrasonic treatment for 0.5h to make the mixture uniform, stirring and evaporating at 100 ℃, drying overnight at 100 ℃, heating to 500 ℃ at 1 ℃/min in air and keeping for 2h to obtain CeO2-MnO2ZSM-5, i.e. catalyst A; finally, the catalyst A is tabletted and ground, and the catalyst A is screened to obtain particles with the size of 40-60 meshes for later use.
(4) Preparation of Pt @ CeO2ZSM-5: the same as in example 7.
(5) And (3) arranging 25mg of the catalyst A at the gas inlet end of the tubular fixed bed reactor, and arranging 25mg of the catalyst B at the gas outlet end of the tubular fixed bed reactor to obtain the two-stage catalyst for treating the tail gas of the diesel vehicle.
Example 19
(1) Preparation of CeO2-MnO2Nanoparticle: the same as in example 18.
(2) Preparation of Pt @ CeO2Core-shell structured nanoparticles: the same as in example 7.
(3) Preparation of CeO2-MnO2/MCM-56：
Taking the CeO with constant volume in the step (1)2-MnO2130mL of the nanoparticle sol solution was added with 0.5g of molecular sieve MCM-56(n (SiO)2)/n(Al2O3) 25), stirring for 4h after ultrasonic treatment for 0.5h to make the mixture uniform, stirring and evaporating at 100 ℃, drying overnight at 100 ℃, heating to 500 ℃ at 1 ℃/min in air and keeping for 2h to obtain CeO2-MnO2/MCM-56, catalyst A; finally, the catalyst A is tabletted and ground, and the catalyst A is screened to obtain particles with the size of 40-60 meshes for later use.
(4) Preparation of Pt @ CeO2[ MCM-56: the same as in example 8.
(5) And (3) arranging 25mg of the catalyst A at the gas inlet end of the tubular fixed bed reactor, and arranging 25mg of the catalyst B at the gas outlet end of the tubular fixed bed reactor to obtain the two-stage catalyst for treating the tail gas of the diesel vehicle.
Example 20
(1) Preparation of CeO2-MnO2Nanoparticle: the same as in example 18.
(2) Preparation of Pt @ CeO2Core-shell structured nanoparticles: the same as in example 7.
(3) Preparation of CeO2-MnO2/BEA：
Taking the CeO with constant volume in the step (1)2-MnO2130mL of nanoparticle sol solution, 0.5g of molecular sieve BEA (n (SiO)2)/n(Al2O3) 19) and ultrasonically treating for 0.5h, stirring for 4h to be uniform, stirring and evaporating at 100 ℃, drying at 100 ℃ overnight, heating to 500 ℃ at the speed of 1 ℃/min in air, and keeping for 2h to obtain CeO2-MnO2/BEA, i.e.catalyst A; finally, the catalyst A is tabletted and ground, and the catalyst A is screened to obtain particles with the size of 40-60 meshes for later use.
(4) Preparation of Pt @ CeO2The ratio of/BEA: the same as in example 14.
(5) And (3) arranging 25mg of the catalyst A at the gas inlet end of the tubular fixed bed reactor, and arranging 25mg of the catalyst B at the gas outlet end of the tubular fixed bed reactor to obtain the two-stage catalyst for treating the tail gas of the diesel vehicle.
Example 21
(1) Mixing the catalyst A prepared in the example 8 with 30% of silica sol and stirring until the slurry is uniform;
(2) mixing the catalyst B prepared in the example 8 with 30% of silica sol and stirring until the slurry is uniform;
(2) calcining 17 mm-diameter and 17 mm-length cordierite in air at 700 ℃ for 2h to remove impurities to obtain a cordierite honeycomb ceramic substrate;
(3) respectively soaking cordierite honeycomb ceramic matrixes in the homogenate obtained in the step (1) and the step (2), taking out after 10min, drying in a drying oven at 100 ℃ for 10h, and roasting in a muffle furnace at 500 ℃ for 2h to respectively obtain a coated honeycomb ceramic catalyst A and a coated honeycomb ceramic catalyst B;
(4) taking the mass ratio of 0.5: 1, wherein the honeycomb ceramic catalyst A of the coating is arranged at the air inlet end of the tubular fixed bed reactor, and the honeycomb ceramic catalyst B of the coating is arranged at the air outlet end of the tubular fixed bed reactor, so as to obtain the two-stage catalyst for treating the tail gas of the diesel vehicle.
Example 22
(1) Mixing the catalyst A prepared in the example 8 with 25% of alumina sol and stirring until the slurry is uniform;
(2) mixing the catalyst B prepared in the example 8 with 25% of aluminum sol and stirring until the slurry is uniform;
(2) calcining 17 mm-diameter and 17 mm-length cordierite in air at 700 ℃ for 2h to remove impurities to obtain a cordierite honeycomb ceramic substrate;
(3) respectively soaking cordierite honeycomb ceramic matrixes in the homogenate obtained in the step (1) and the step (2), taking out after 10min, drying in a drying oven at 100 ℃ for 10h, and roasting in a muffle furnace at 500 ℃ for 2h to respectively obtain a coated honeycomb ceramic catalyst A and a coated honeycomb ceramic catalyst B;
(4) taking the mass ratio of 1: 1, wherein the honeycomb ceramic catalyst A of the coating is arranged at the air inlet end of the tubular fixed bed reactor, and the honeycomb ceramic catalyst B of the coating is arranged at the air outlet end of the tubular fixed bed reactor, so as to obtain the two-stage catalyst for treating the tail gas of the diesel vehicle.
Example 23
(1) Mixing the catalyst A prepared in the example 8 with 30% of silica sol and stirring until the slurry is uniform;
(2) mixing the catalyst B prepared in the example 8 with 30% of silica sol and stirring until the slurry is uniform;
(2) cleaning a metal honeycomb carrier with the diameter of 17mm and the length of 17mm in an ultrasonic cleaning machine, drying, calcining in a muffle furnace at 900 ℃ for 2h, and removing impurities to obtain the metal honeycomb carrier;
(3) respectively soaking the metal honeycomb carrier in the homogenate obtained in the step (1) and the step (2), taking out after 10min, drying in a drying oven at 100 ℃ for 10h, and roasting in a muffle furnace at 500 ℃ for 2h to respectively obtain a coated metal honeycomb catalyst A and a coated metal honeycomb catalyst B;
(4) taking the mass ratio of 2: 1, and a coated metal honeycomb catalyst A and a coated metal honeycomb catalyst B, wherein the coated metal honeycomb catalyst A is arranged at the air inlet end of the tubular fixed bed reactor, and the coated metal honeycomb catalyst B is arranged at the air outlet end of the tubular fixed bed reactor, so that the two-stage catalyst for treating the tail gas of the diesel vehicle is obtained.
The activity of the two-section catalyst for catalytic reduction of nitrogen oxides provided by embodiments 1-23 of the invention is detected, and the experimental conditions are as follows:
the reaction gas is NO: 500ppm, NH3：500ppm，O2: 5 percent, and Ar is balance gas;
the total flow of gas is 100mL/min, and the reaction space velocity (GHSV) is 240000 mL/g/h;
the reaction temperature range is from 150 ℃ to 550 ℃;
the gases were detected by mass spectrometry.
The results are shown in Table 1.
TABLE 1 Activity of two-stage catalysts for catalytic reduction of Nitrogen oxides provided in examples 1 to 23 of the present invention
Data of
As shown in Table 1, the two-stage catalysts provided in the embodiments 1-20 of the present invention have a temperature of 150--1Under the condition, the nitrogen oxide conversion activity is higher than 80%, the stability is good, and the N is excellent at high temperature2And (4) selectivity.
Comparative example 1
25mg of the catalyst B prepared in example 8 was placed at the inlet end of a tubular fixed bed reactor and 25mg of the catalyst A prepared in example 8 was placed at the outlet end of the tubular fixed bed reactor to obtain a two-stage catalyst for treating tail gas of diesel vehicles.
Comparative example 2
25mg of the catalyst B prepared in example 8 and 25mg of the catalyst A prepared in example 8 were mixed and equally divided into two portions, which were respectively disposed at the inlet end and the outlet end of the tubular fixed bed reactor, to obtain a two-stage catalyst for treating diesel vehicle exhaust.
The activity of the two-stage catalyst provided by comparative examples 1-2 in catalytic reduction of nitrogen oxides was tested under the same conditions, and the test results are shown in table 2.
Table 2 activity data of two-stage catalyst for catalytic reduction of nitrogen oxides provided in comparative examples 1-2
As can be seen from Table 2, the two-stage catalysts provided in comparative examples 1-2 have drastically reduced catalytic performance at 300 ℃.
Comparative example 3
The 50mg of the catalyst a prepared in example 10 was equally divided into two parts and disposed at the inlet end and the outlet end of the tubular fixed bed reactor, respectively, to obtain a two-stage catalyst for diesel exhaust treatment.
Comparative example 4
The 50mg of the catalyst B prepared in example 10 was equally divided into two parts and disposed at the inlet end and the outlet end of the tubular fixed bed reactor, respectively, to obtain a two-stage catalyst for diesel exhaust treatment.
The activity of the two-stage catalyst provided in comparative examples 3 to 4 in catalytic reduction of nitrogen oxides was measured under the same conditions and compared with example 10, and the results are shown in fig. 5. As can be seen from fig. 5, the two-stage catalyst provided in embodiment 10 of the present invention has high nitrogen oxide removal effect and selectivity in a wider temperature range than comparative ratios 3 to 4.
The performance of the two-stage catalyst provided by the embodiment 9 and the comparative examples 1 to 2 of the invention for removing carbon particulate matters is detected, and the experimental conditions are as follows:
0.0028g of carbon black was mixed with the catalyst at the inlet end of the tubular fixed bed reactor; the reaction gas is NO: 500ppm, O2: 5 percent, and Ar is balance gas;
the total flow of gas is 40mL/min, and the reaction space velocity (GHSV) is 96000 mL/g/h;
the reaction temperature range is from 150 ℃ to 700 ℃;
the gases were detected by mass spectrometry.
The results are shown in Table 3.
TABLE 3 carbon particulate removal performance of the two-stage catalysts provided in example 9 and comparative examples 1-2
According to
| Group of | Ts(℃) | Tm(℃) | Te(℃) |
| Example 9 | 200 | 476 | 563 |
| Comparative example 1 | 400 | 605 | 668 |
| Comparative example 2 | 450 | 610 | 673 |
In Table 3, Ts is the conversion of carbon black to CO2At an initial temperature of Tm that the carbon black is converted to CO2Peak temperature of (Te) conversion of carbon black to CO2The end temperature of (c). As can be seen from table 3, the two-stage catalyst provided in example 9 of the present invention has better performance of removing carbon particles than comparative examples 1 to 2, and can remove carbon particles in the exhaust gas at about 450 ℃.
Oxidation of NH on the two-stage catalyst provided in example 7 of the invention3The experimental conditions are as follows:
the reaction gas being NH3: concentrations of 1000ppm, 500ppm, 200ppm, 100ppm, respectively, O2: 5 percent, Ar is equilibrium gas, the total flow of the gas is 40mL/min, and the reaction space velocity (GHSV) is 96000 mL/g/h;
the reaction temperature range is from 150 ℃ to 550 ℃;
the gases were detected by mass spectrometry.
The results are shown in Table 4.
Table 4 example 7 provides a two-stage catalyst at different NH3Oxidation of NH at concentration3Performance data of
As can be seen from Table 4, the two-stage catalyst of example 7 of the present invention has the function of eliminating NH slip3The function of (1).
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims (3)
1. A two-stage catalyst for treating tail gas of diesel vehicle is composed of a catalyst A at gas inlet end and a catalyst B at gas outlet end;
the catalyst A has a general formula shown in formula (I):
CeO2-X/molecular sieve formula (I);
wherein X is selected from CuO and Fe2O3Or MnO2(ii) a In the formula (I), CeO2And the molar ratio of X to X is (3-19): 1, the molecular sieve is selected from ZSM-5, MCM-56 or BEA, and the CeO2-the mass ratio of X to molecular sieve is 1: (1-10);
the catalyst B has a general formula shown in formula (II):
M@CeO2molecular sieve formula (II);
wherein M is selected from Rh, Pt or Pd; in the formula (II), M and CeO2In a molar ratio of 1: (8-32) of a first polymer,the molecular sieve is selected from ZSM-5, MCM-56 or BEA, and the M @ CeO2And the mass ratio of the molecular sieve to the molecular sieve is 1: (1-10);
the mass ratio of the catalyst A to the catalyst B is (0.5-3): 1;
the preparation method of the two-stage catalyst comprises the following steps:
a) carrying out hydrothermal reaction on a cerium source, an X' source and triethylamine in a first solvent to obtain CeO2-X nanoparticles; the X' source is selected from a copper source, an iron source or a manganese source;
b) carrying out coprecipitation reaction on an M' source, a cerium source and ammonia water in a second solvent to obtain M @ CeO2Core-shell structured nanoparticles; the source of M' is selected from a source of rhodium, a source of platinum, or a source of palladium;
c) subjecting the CeO obtained in step a)2-X nanoparticles and M @ CeO obtained in step b)2Loading the core-shell structure nano particles with a molecular sieve respectively to obtain a catalyst A and a catalyst B respectively; said CeO in step c)2-the average particle size of the X nanoparticles is 3nm to 5 nm; the M @ CeO2The average particle size of the core-shell structure nanoparticles is 45 nm-55 nm;
d) arranging a catalyst A at an air inlet end and a catalyst B at an air outlet end to obtain a two-section catalyst for treating the tail gas of the diesel vehicle;
the steps a) and b) are not limited in order.
2. The two-stage catalyst according to claim 1, wherein the temperature of the hydrothermal reaction in step a) is 160 ℃ to 200 ℃ for 20h to 30 h.
3. The two-stage catalyst according to claim 1, wherein the temperature of the co-precipitation reaction in step b) is 50 ℃ to 70 ℃ and the time is 0.5h to 1.5 h.
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| CN110385124B (en) * | 2018-04-16 | 2021-01-26 | 浙江大学 | Preparation of MnO by staged reactionx-CeO2Process for mixed oxide catalyst |
| CN108435220A (en) * | 2018-04-26 | 2018-08-24 | 中国科学院长春应用化学研究所 | A kind of combined type SCR denitration that anti-poisoning capability is strong and its application |
| CN110052287B (en) * | 2019-05-17 | 2022-10-11 | 湘潭大学 | Core-shell structure molecular sieve catalyst for cooperatively controlling NO and toluene and preparation method thereof |
| CN112279266B (en) * | 2020-12-29 | 2021-04-06 | 中化学科学技术研究有限公司 | Cu-SSZ-13@ SSZ-13 core-shell type molecular sieve and preparation method and application thereof |
| CN113457730A (en) * | 2021-06-17 | 2021-10-01 | 江苏博霖环保科技有限公司 | Preparation method of porous SCR catalyst for treating diesel engine tail gas |
| CN113385221A (en) * | 2021-07-14 | 2021-09-14 | 安徽元琛环保科技股份有限公司 | Ultra-high temperature catalyst based on metal honeycomb carrier and preparation method thereof |
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