CN116493009B - Palladium-based pseudo-binary alloy catalyst and preparation method and application thereof - Google Patents
Palladium-based pseudo-binary alloy catalyst and preparation method and application thereof Download PDFInfo
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- CN116493009B CN116493009B CN202310708255.2A CN202310708255A CN116493009B CN 116493009 B CN116493009 B CN 116493009B CN 202310708255 A CN202310708255 A CN 202310708255A CN 116493009 B CN116493009 B CN 116493009B
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- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 title claims abstract description 155
- 229910002056 binary alloy Inorganic materials 0.000 title claims abstract description 84
- 239000003054 catalyst Substances 0.000 title claims abstract description 82
- 229910052763 palladium Inorganic materials 0.000 title claims abstract description 59
- 238000002360 preparation method Methods 0.000 title claims abstract description 18
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims abstract description 74
- 239000002105 nanoparticle Substances 0.000 claims abstract description 73
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Substances [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims abstract description 34
- 239000011148 porous material Substances 0.000 claims abstract description 14
- 229910052779 Neodymium Inorganic materials 0.000 claims abstract description 13
- 229910052772 Samarium Inorganic materials 0.000 claims abstract description 13
- 229910052697 platinum Inorganic materials 0.000 claims abstract description 7
- 238000002156 mixing Methods 0.000 claims description 47
- 239000002904 solvent Substances 0.000 claims description 42
- 239000011259 mixed solution Substances 0.000 claims description 38
- 150000003839 salts Chemical class 0.000 claims description 38
- 238000003756 stirring Methods 0.000 claims description 38
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 36
- 238000001035 drying Methods 0.000 claims description 32
- 239000000843 powder Substances 0.000 claims description 29
- 238000000605 extraction Methods 0.000 claims description 27
- 239000002131 composite material Substances 0.000 claims description 19
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical group CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 claims description 19
- 238000006722 reduction reaction Methods 0.000 claims description 17
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical group ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 claims description 16
- 239000003638 chemical reducing agent Substances 0.000 claims description 15
- 239000006185 dispersion Substances 0.000 claims description 14
- 230000032683 aging Effects 0.000 claims description 13
- 239000007788 liquid Substances 0.000 claims description 12
- 238000000034 method Methods 0.000 claims description 12
- 238000005859 coupling reaction Methods 0.000 claims description 10
- 238000000926 separation method Methods 0.000 claims description 9
- 238000004729 solvothermal method Methods 0.000 claims description 9
- GPNDARIEYHPYAY-UHFFFAOYSA-N palladium(ii) nitrate Chemical group [Pd+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O GPNDARIEYHPYAY-UHFFFAOYSA-N 0.000 claims description 7
- KLFRPGNCEJNEKU-FDGPNNRMSA-L (z)-4-oxopent-2-en-2-olate;platinum(2+) Chemical group [Pt+2].C\C([O-])=C\C(C)=O.C\C([O-])=C\C(C)=O KLFRPGNCEJNEKU-FDGPNNRMSA-L 0.000 claims description 6
- CFYGEIAZMVFFDE-UHFFFAOYSA-N neodymium(3+);trinitrate Chemical compound [Nd+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O CFYGEIAZMVFFDE-UHFFFAOYSA-N 0.000 claims description 5
- YZDZYSPAJSPJQJ-UHFFFAOYSA-N samarium(3+);trinitrate Chemical group [Sm+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O YZDZYSPAJSPJQJ-UHFFFAOYSA-N 0.000 claims description 5
- XURCIPRUUASYLR-UHFFFAOYSA-N Omeprazole sulfide Chemical compound N=1C2=CC(OC)=CC=C2NC=1SCC1=NC=C(C)C(OC)=C1C XURCIPRUUASYLR-UHFFFAOYSA-N 0.000 claims description 4
- 238000004321 preservation Methods 0.000 claims description 2
- 230000008569 process Effects 0.000 claims description 2
- 229910052684 Cerium Inorganic materials 0.000 claims 1
- 229910045601 alloy Inorganic materials 0.000 abstract description 21
- 239000000956 alloy Substances 0.000 abstract description 21
- 230000003197 catalytic effect Effects 0.000 abstract description 12
- 230000009467 reduction Effects 0.000 abstract description 6
- 230000003647 oxidation Effects 0.000 abstract description 5
- 238000007254 oxidation reaction Methods 0.000 abstract description 5
- 239000012752 auxiliary agent Substances 0.000 abstract description 3
- 230000005540 biological transmission Effects 0.000 abstract description 3
- 238000004377 microelectronic Methods 0.000 abstract description 3
- 239000000463 material Substances 0.000 description 20
- 238000001914 filtration Methods 0.000 description 19
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical group O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 14
- 239000003513 alkali Substances 0.000 description 12
- 239000007789 gas Substances 0.000 description 12
- 239000012266 salt solution Substances 0.000 description 12
- 238000000975 co-precipitation Methods 0.000 description 11
- 239000000243 solution Substances 0.000 description 11
- 238000005406 washing Methods 0.000 description 11
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 description 10
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 10
- 239000001099 ammonium carbonate Substances 0.000 description 10
- 235000012501 ammonium carbonate Nutrition 0.000 description 10
- 235000011114 ammonium hydroxide Nutrition 0.000 description 10
- 239000007864 aqueous solution Substances 0.000 description 10
- 239000007853 buffer solution Substances 0.000 description 10
- 239000008367 deionised water Substances 0.000 description 10
- 229910021641 deionized water Inorganic materials 0.000 description 10
- 239000000706 filtrate Substances 0.000 description 10
- 230000007935 neutral effect Effects 0.000 description 10
- 239000002244 precipitate Substances 0.000 description 10
- 239000012876 carrier material Substances 0.000 description 9
- 238000006243 chemical reaction Methods 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 7
- 238000005119 centrifugation Methods 0.000 description 6
- 238000011065 in-situ storage Methods 0.000 description 6
- 239000002245 particle Substances 0.000 description 5
- 238000000197 pyrolysis Methods 0.000 description 5
- 238000010992 reflux Methods 0.000 description 5
- 229910052726 zirconium Inorganic materials 0.000 description 5
- 238000010438 heat treatment Methods 0.000 description 4
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical group CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 description 3
- 239000007795 chemical reaction product Substances 0.000 description 3
- -1 dimethyl diamide Chemical compound 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 229910021645 metal ion Inorganic materials 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 239000013078 crystal Substances 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 239000000047 product Substances 0.000 description 2
- 238000000746 purification Methods 0.000 description 2
- 230000002195 synergetic effect Effects 0.000 description 2
- 238000009210 therapy by ultrasound Methods 0.000 description 2
- 231100000331 toxic Toxicity 0.000 description 2
- 230000002588 toxic effect Effects 0.000 description 2
- 150000000703 Cerium Chemical class 0.000 description 1
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 1
- 229910001260 Pt alloy Inorganic materials 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- AZDRQVAHHNSJOQ-UHFFFAOYSA-N alumane Chemical class [AlH3] AZDRQVAHHNSJOQ-UHFFFAOYSA-N 0.000 description 1
- 238000000498 ball milling Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 238000010494 dissociation reaction Methods 0.000 description 1
- 230000005593 dissociations Effects 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 239000005431 greenhouse gas Substances 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 229910000765 intermetallic Inorganic materials 0.000 description 1
- 238000011068 loading method Methods 0.000 description 1
- 239000003345 natural gas Substances 0.000 description 1
- 239000003960 organic solvent Substances 0.000 description 1
- 238000012946 outsourcing Methods 0.000 description 1
- 230000033116 oxidation-reduction process Effects 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000006479 redox reaction Methods 0.000 description 1
- 238000000638 solvent extraction Methods 0.000 description 1
- 230000001360 synchronised effect Effects 0.000 description 1
- 230000009466 transformation Effects 0.000 description 1
- 150000003754 zirconium Chemical class 0.000 description 1
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
- B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/56—Platinum group metals
- B01J23/63—Platinum group metals with rare earths or actinides
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- 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
- B01D53/922—Mixtures of carbon monoxide or hydrocarbons and nitrogen oxides
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- 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
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- B01D2255/1023—Palladium
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Abstract
The invention belongs to the technical field of catalysts, and particularly relates to a palladium-based pseudo-binary alloy catalyst, and a preparation method and application thereof. The palladium-based pseudo-binary alloy catalyst provided by the invention comprises Ce 0.4 Zr 0.6 ‑γ‑Al 2 O 3 Support and load on the Ce 0.4 Zr 0.6 ‑γ‑Al 2 O 3 M is doped with PtPd pseudo-binary alloy nano particles on the surface of a carrier pore channel, wherein M is Sm, in or Nd. According to the palladium-based pseudo-binary alloy catalyst provided by the invention, the supported part is the M-doped PtPd alloy nano particle with the pseudo-binary alloy structure, and the auxiliary agent M (Sm, in or Nd) enhances the electron cloud density of active center Pd, so that the low-temperature catalytic oxidation capability of the catalyst is improved, the microelectronic environment of Pd is modulated by adding Pt, the stronger electron transmission capability between Pt and Pd bimetallic is achieved, the reduction performance of the catalyst is improved, and the palladium-based pseudo-binary alloy catalyst has high catalytic activity and selectivity.
Description
Technical Field
The invention belongs to the technical field of catalysts, and particularly relates to a palladium-based pseudo-binary alloy catalyst, and a preparation method and application thereof.
Background
Unburned CH in tail gas of natural gas automobiles (NGVs) 4 Is a strong greenhouse gas, and has the potential of CO in the 100-year period 2 21 times of (2); NO (NO) x Is responsible for ozone and PM in the atmosphere 2.5 Important precursors for contamination. Thus, CH is reduced 4 And NO x The emission (mainly NO) is one of the key problems that NGVs exhaust catalysts need to solve. In the catalytic purification process of NGVs tail gas, CO+O 2 Is superior to the redox reaction of co+no, resulting in NO being difficult to purify and N at low temperatures 2 Poor selectivity, promote CH 4 And (5) completely purifying. Thus, promotion of CH at low temperature 4 The +NO coupling reaction is CH in tail gas of NGVs 4 And NO, the most effective technical approach for synergistic purification.
The palladium (Pd) supported catalyst is an active clean CH 4 And NO, but CH 4 The dissociation and activation energy of the C-H bond in the catalyst is high, NO is difficult to be dissociated and activated on Pd, and even the catalyst has toxic effect on Pd, so that the palladium (Pd) supported catalyst has toxic effect on CH 4 The synergistic catalytic conversion effect with NO is poor.
Disclosure of Invention
Accordingly, the present invention is directed to a palladium-based pseudo-binary alloy catalyst, and a preparation method and application thereof, wherein the palladium-based pseudo-binary alloy catalyst has high catalytic activity and selectivity, and is used for catalyzing CH in NGVs tail gas 4 For CH during coupling reaction with NO 4 And NO has high conversion rate to N 2 Has high selectivity.
In order to achieve the above object, the present invention provides the following technical solutions:
the invention provides a palladium-based pseudo-binary alloy catalyst, which comprises Ce 0.4 Zr 0.6 -γ-Al 2 O 3 Support and load on the Ce 0.4 Zr 0.6 -γ-Al 2 O 3 M is doped with PtPd pseudo-binary alloy nano particles on the surface of a carrier pore channel, wherein M is Sm, in or Nd.
Preferably, the Ce 0.4 Zr 0.6 -γ-Al 2 O 3 The carrier comprises Ce 0.4 Zr 0.6 With gamma-Al 2 O 3 The Ce is 0.4 Zr 0.6 With gamma-Al 2 O 3 The mass ratio of (1) to (0.5) is 1; ce in the palladium-based pseudo-binary alloy catalyst 0.4 Zr 0.6 -γ-Al 2 O 3 The mass percentage of the carrier is 88-99.3%.
Preferably, the palladium-based pseudo-binary alloy catalyst comprises 0.1-1% of Pt by mass and 0.1-1% of Pd by mass.
Preferably, the mass percentage of M in the palladium-based pseudo-binary alloy catalyst is 0.5-10%.
The invention also provides a preparation method of the palladium-based pseudo-binary alloy catalyst, which comprises the following steps:
mixing Pd salt, M salt, a first solvent and a double reducing agent, and then carrying out double reduction reaction to obtain PdM nano particles; m is Sm, in or Nd;
mixing the PdM nano-particles, organic Pt salt and a second solvent, and performing solvothermal reaction to obtain M-doped PtPd pseudo-binary alloy nano-particles;
dropwise adding the aqueous dispersion of the M-doped PtPd pseudo-binary alloy nano particles into Ce 0.4 Zr 0.6 -γ-Al 2 O 3 Sequentially stirring and standing the mixed solution obtained by mixing the carrier and the first extraction solvent to obtain a two-phase mixed solution;
mixing the two-phase mixed solution with a second extraction solvent, stirring and extracting, and then sequentially aging, solid-liquid separation and drying to obtain composite dry powder;
and roasting the composite dry powder to obtain the palladium-based pseudo-binary alloy catalyst.
Preferably, the Pd salt is palladium nitrate; the organic Pt salt is platinum acetylacetonate and/or dinitroso diammine platinum; the M salt is samarium nitrate, neodymium nitrate or indium nitrate.
Preferably, the double reducing agent is NaBH 4 And ethylene glycol; the NaBH 4 And ethylene glycol in a mass ratio of (0.001-0.1): 1.
Preferably, the first extraction solvent is n-hexane; the second extraction solvent is chloroform.
Preferably, the roasting temperature is 400-550 ℃, and the heat preservation time is 1-3 h.
The invention also provides the palladium-based pseudo-binary alloy catalyst prepared by the technical scheme or the preparation method of the technical scheme, and the palladium-based pseudo-binary alloy catalyst is used for catalyzing CH 4 And the use in NO coupling reactions.
The invention provides a palladium-based pseudo-binary alloy catalyst, which comprises Ce 0.4 Zr 0.6 -γ-Al 2 O 3 Support and load on the Ce 0.4 Zr 0.6 -γ-Al 2 O 3 M is doped with PtPd pseudo-binary alloy nano particles on the surface of a carrier pore channel, wherein M is Sm, in or Nd. The M-doped PtPd alloy nano particles with the loading part of the pseudo-binary alloy structure In the palladium-based pseudo-binary alloy catalyst provided by the invention are characterized In that an auxiliary agent M (Sm, in or Nd) is doped In the PtPd pseudo-binary alloy, so that the electron cloud density of an active center Pd is enhanced, the low-temperature catalytic oxidation capability of the catalyst is improved, the microelectronic environment of Pd is modulated by adding Pt, the stronger electron transmission capability between Pt and Pd bimetallic is improved, and the reduction performance of the catalyst is improved, so that the palladium-based pseudo-binary alloy catalyst has high catalytic activity and selectivity and is used for catalyzing CH In NGVs tail gas 4 And the coupling reaction of NO is favorable for CH 4 And low temperature catalytic oxidation of NO to CH 4 And NO has high conversion rate to N 2 Has high selectivity.
Drawings
FIG. 1 shows Pd/Ce prepared in comparative example 1 and Pd-based pseudo-binary alloy catalysts prepared in examples 1 to 3 of the present invention 0.4 Zr 0.6 -γ-Al 2 O 3 Catalyst for catalyzing CH in NGVs tail gas 4 Activity profile of the transformation;
FIG. 2 shows Pd/Ce prepared in comparative example 1 and Pd-based pseudo-binary alloy catalysts prepared in examples 1 to 3 of the present invention 0.4 Zr 0.6 -γ-Al 2 O 3 An activity curve graph of NO conversion in the tail gas of the NGVs catalyzed by the catalyst;
FIG. 3 shows palladium groups prepared in examples 1 to 3 of the present inventionPseudo-binary alloy catalyst and Pd/Ce prepared in comparative example 1 0.4 Zr 0.6 -γ-Al 2 O 3 Catalyst for catalyzing CH in NGVs tail gas 4 And NO to generate N 2 Is a graph of selectivity of (2).
Detailed Description
The invention provides a palladium-based pseudo-binary alloy catalyst, which comprises Ce 0.4 Zr 0.6 -γ-Al 2 O 3 Support and load on the Ce 0.4 Zr 0.6 -γ-Al 2 O 3 M is doped with PtPd pseudo-binary alloy nano particles on the surface of a carrier pore channel, wherein M is Sm, in or Nd.
The palladium-based pseudo-binary alloy catalyst provided by the invention comprises Ce 0.4 Zr 0.6 -γ-Al 2 O 3 A carrier.
In the present invention, the Ce 0.4 Zr 0.6 -γ-Al 2 O 3 The carrier is preferably Ce 0.4 Zr 0.6 And gamma-Al 2 O 3 Mechanically mixing to obtain the final product; the Ce is 0.4 Zr 0.6 And gamma-Al 2 O 3 Preferably obtained by outsourcing or self-made; the mechanical mixing is preferably ball milling; the rotational speed of the ball mill is preferably 800rpm.
In the present invention, the Ce 0.4 Zr 0.6 The preparation method of (2) preferably comprises the following steps: dropwise adding an alkali solution into a mixed solution of cerium salt and zirconium salt for precipitation, and sequentially aging, filtering, washing, drying and roasting to obtain Ce 0.4 Zr 0.6 . In an embodiment of the present invention, the Ce 0.4 Zr 0.6 The preparation method of (a) comprises the following steps: ce (NO) was added at a concentration of 10 wt% 3 ) 3 ˙6H 2 Aqueous O solution with 10wt.% Zr (NO 3 ) 4 Mixing aqueous solutions, adding a double-alkali buffer solution consisting of ammonia water and ammonium carbonate in a molar ratio of 3:3 to maintain the pH value at 8.8, performing coprecipitation, aging the obtained precipitate at 100 ℃ for 12 hours, sequentially and circularly and repeatedly filtering and washing the obtained material until the obtained filtrate tends to be neutral, drying the obtained material at 120 ℃ for 24 hours, and roasting the obtained powder sample at 600 ℃ for 3 hours to obtain Ce 0.4 Zr 0.6 。
In the present invention, the gamma-Al 2 O 3 The preparation method of (2) preferably comprises the following steps: dripping alkali solution into aluminum salt solution for coprecipitation, and sequentially aging, filtering, washing, drying and roasting to obtain gamma-Al 2 O 3 . In an embodiment of the present invention, the γ -Al 2 O 3 The preparation method of (a) comprises the following steps: al (NO) with a concentration of 10wt.% 3 ) 3 ˙9H 2 O aqueous solution, adding a double-alkali buffer solution consisting of ammonia water and ammonium carbonate in a molar ratio of 3:3 to maintain the pH value at 8.8, performing coprecipitation, aging the obtained precipitate at 100 ℃ for 12 hours, sequentially and circularly and repeatedly filtering and washing the obtained material until the obtained filtrate tends to be neutral, drying the obtained material at 120 ℃ for 24 hours, and roasting the obtained powder sample at 950 ℃ for 3 hours to obtain gamma-Al 2 O 3 。
In the present invention, the Ce 0.4 Zr 0.6 -γ-Al 2 O 3 The carrier comprises Ce 0.4 Zr 0.6 With gamma-Al 2 O 3 The Ce is 0.4 Zr 0.6 With gamma-Al 2 O 3 The mass ratio of (1) to (0.5) is preferably 1, more preferably (0.6) to (0.8); ce in the palladium-based pseudo-binary alloy catalyst 0.4 Zr 0.6 -γ-Al 2 O 3 The mass percentage of the carrier is preferably 88-99.3%; the Ce is 0.4 Zr 0.6 -γ-Al 2 O 3 The particle diameter of the carrier is preferably 3 to 20. Mu.m, more preferably 5 to 15. Mu.m, and the specific surface area is preferably 140 to 220. Mu.m 2 Preferably 140 to 180m 2 /g。
In the present invention, the mass percentage of Pt in the palladium-based pseudo-binary alloy catalyst is preferably 0.1 to 1%, more preferably 0.1 to 0.3%, the mass percentage of Pd is preferably 0.1 to 1%, more preferably 0.5 to 1%, and the mass percentage of M is preferably 0.5 to 10%, more preferably 0.5 to 3%.
In the invention, the particle size of the M-doped PtPd alloy nano particles is preferably 1-10 nm, more preferably 1-5 nm; the particle size of the palladium-based pseudo-binary alloy catalyst is preferably 1-10 nm, more preferably 1-5 nm; the palladium-based pseudo-binary alloy catalysisThe specific surface area of the agent is preferably 130-210 m 2 Preferably 140 to 180m 2 /g。
According to the palladium-based pseudo-binary alloy catalyst provided by the invention, the supported part is the M (Sm, in or Nd) doped PtPd pseudo-binary alloy nano particles with a pseudo-binary alloy structure, pt is In an atomic dispersion state, and the auxiliary agent M (Sm, in or Nd) is doped In the PtPd pseudo-binary alloy, so that the electron cloud density of an active center Pd is enhanced, the low-temperature catalytic oxidation capability of the catalyst is improved, the microelectronic environment of Pd is modulated by adding Pt, the stronger electron transmission capability between Pt and Pd bimetallic is improved, and the reduction performance of the catalyst is improved, so that the palladium-based pseudo-binary alloy catalyst has high catalytic activity and selectivity.
The invention also provides a preparation method of the palladium-based pseudo-binary alloy catalyst, which comprises the following steps:
mixing Pd salt, M salt, a first solvent and a double reducing agent, and then carrying out double reduction reaction to obtain PdM nano particles; m is Sm, in or Nd;
mixing the PdM nano-particles, organic Pt salt and a second solvent, and performing solvothermal reaction to obtain M-doped PtPd pseudo-binary alloy nano-particles;
dropwise adding the aqueous dispersion of the M-doped PtPd pseudo-binary alloy nano particles into Ce 0.4 Zr 0.6 -γ-Al 2 O 3 Sequentially stirring and standing the mixed solution obtained by mixing the carrier and the first extraction solvent to obtain a two-phase mixed solution;
mixing the two-phase mixed solution with a second extraction solvent, stirring and extracting, and then sequentially aging, solid-liquid separation and drying to obtain composite dry powder;
and roasting the composite dry powder to obtain the palladium-based pseudo-binary alloy catalyst.
The present invention is not limited to the specific source of the raw materials used, and may be commercially available products known to those skilled in the art, unless otherwise specified.
The invention mixes Pd salt, M salt, first solvent and double reducing agent, and then carries out double reduction reaction to obtain double reduction reaction products.
In the present invention, the Pd salt is preferably palladium nitrate; the M salt is preferably samarium nitrate, neodymium nitrate or indium nitrate, more preferably samarium nitrate or neodymium nitrate; the first solvent is preferably deionized water; the double reducing agent is preferably NaBH 4 And ethylene glycol; the NaBH 4 The mass ratio of ethylene glycol to ethylene glycol is preferably (0.001 to 0.1): 1, more preferably (0.001 to 0.05): 1.
In the present invention, the mass ratio of the Pd salt to the M salt is preferably (0.01 to 2): 1, more preferably (0.5 to 1): 1; the molar ratio of the Pd salt to the double reducing agent is preferably (0.001 to 1): 1, more preferably (0.001 to 0.01): 1.
In the present invention, the mixing of the Pd salt, the M salt, the first solvent and the double reducing agent is preferably: and after the Pd salt, the M salt and the first solvent are first mixed, sequentially carrying out ultrasonic treatment and stirring, and carrying out second mixing on the obtained mixed salt solution and the double reducing agent. In the invention, the mass percentage of Pd salt in the mixed salt solution is preferably 0.05-0.15%, more preferably 0.1-0.15%; the mass percentage of the M salt in the mixed salt solution is preferably 0.05-0.2%, more preferably 0.1-0.17%; the power of the ultrasonic wave is preferably 150-650W, more preferably 240-500W; the time of the ultrasonic treatment is preferably 15-30 min, more preferably 30min; the stirring speed is preferably 600-1500 rpm, more preferably 800-1000 rpm; the stirring time is preferably 1 to 6 hours, more preferably 1 to 5 hours.
In the present invention, the double reduction reaction is preferably performed under the condition of condensing reflux; the temperature of the double reduction reaction is preferably 50-100 ℃, more preferably 80 ℃; the time of the double reduction reaction is preferably 12 to 24 hours, more preferably 12 hours.
In the double reduction reaction process, the invention adopts double reducing agents to mainly ensure that the size of the PdM nano-particles is easier to control and more uniform, and the Pd-M is more uniformly mixed, wherein the strong reducing agents rapidly reduce metal ions in the mixed solution to form crystal nuclei, the weak reducing agents continuously reduce the metal ions in the mixed solution on the basis, ensure that the metal ions continuously grow on the crystal nuclei, form the PdM nano-particles with uniform nano-particle sizes and form intermetallic compound structures with uniformly mixed bimetallic nano-particles.
After the double reduction reaction product is obtained, the invention preferably carries out solid-liquid separation and drying on the double reduction reaction product in sequence to obtain the PdM nano-particles. In the present invention, the solid-liquid separation is preferably performed by centrifugation; the rotational speed of the centrifugation is preferably 8000 to 12000rpm, more preferably 10000 to 12000rpm; the time of the centrifugation is preferably 30 to 60 minutes, more preferably 30 to 40 minutes; the drying temperature is preferably 80 to 100 ℃, more preferably 90 to 100 ℃; the drying time is preferably 12 to 24 hours, more preferably 12 to 18 hours.
In the present invention, the particle diameter of the PdM nanoparticle is preferably 1.0 to 10nm, more preferably 1 to 5nm.
After the PdM nanoparticles are obtained, the PdM nanoparticles, the organic Pt salt and the second solvent are mixed and subjected to solvothermal reaction.
In the present invention, the organic Pt salt is preferably platinum acetylacetonate and/or dinitroso diammine platinum, more preferably platinum acetylacetonate; the second solvent is preferably dimethylformamide; the mass ratio of the PdM nanoparticle to the organic Pt salt is preferably (1.1 to 110): 1, more preferably (5 to 15): 1; the mass ratio of the organic Pt salt to the second solvent is preferably (0.0002 to 0.1): 1, more preferably (0.001 to 0.003): 1.
In the present invention, mixing the PdM nanoparticles, the organic Pt salt, and the second solvent is preferably performed by dissolving the PdM nanoparticles, the organic Pt salt, and the second solvent, and stirring; the stirring speed is preferably 600-1500 rpm, more preferably 800-1000 rpm; the stirring time is preferably 15 to 30 minutes, more preferably 20 to 30 minutes.
In the present invention, the temperature of the solvothermal reaction is preferably 60 to 150 ℃, more preferably 80 to 110 ℃; the in-situ pyrolysis time is preferably 12-24 hours, more preferably 16-24 hours; the heating rate to the in-situ pyrolysis temperature is preferably 1 to 5 ℃/min, more preferably 2 to 5 ℃/min.
In the solvothermal reaction, the organic Pt salt is continuously thermally decomposed and nucleates and grows, pt grows in situ on the surfaces of the PdM nano particles, the atomically dispersed Pt nano particles are achieved, and Pd-Pt alloy is formed with Pd.
After the solvothermal reaction is finished, the product obtained by the solvothermal reaction is preferably subjected to solid-liquid separation and drying in sequence to obtain the M-doped PtPd pseudo-binary alloy nano-particles. In the present invention, the solid-liquid separation is preferably performed by centrifugation; the rotational speed of the centrifugation is preferably 8000 to 12000rpm, more preferably 10000 to 12000rpm; the time of the centrifugation is preferably 30 to 60 minutes, more preferably 30 to 40 minutes; the drying temperature is preferably 80 to 100 ℃, more preferably 90 to 100 ℃; the drying time is preferably 12 to 24 hours, more preferably 12 to 16 hours.
In the present invention, the particle diameter of the M-doped PtPd pseudo binary alloy nanoparticle is preferably 1 to 10nm, more preferably 1 to 5nm.
After the M-doped PtPd pseudo-binary alloy nano particles are obtained, the invention adds the aqueous dispersion of the M-doped PtPd pseudo-binary alloy nano particles into Ce drop by drop 0.4 Zr 0.6 -γ-Al 2 O 3 And (3) stirring and standing the mixed solution obtained by mixing the carrier and the first extraction solvent in sequence to obtain a two-phase mixed solution.
In the invention, the aqueous dispersion of the M-doped PtPd pseudo-binary alloy nano-particles is preferably prepared by dispersing the M-doped PtPd pseudo-binary alloy nano-particles in deionized water; the mass of the M-doped PtPd pseudo-binary alloy nano particles is preferably the Ce 0.4 Zr 0.6 -γ-Al 2 O 3 The mass of the carrier is 0.7 to 12%, more preferably 0.7 to 2%.
In the invention, the first extraction solvent is n-hexane; the Ce is 0.4 Zr 0.6 -γ-Al 2 O 3 Ce in the mixed solution obtained by mixing the carrier and the first extraction solvent 0.4 Zr 0.6 -γ-Al 2 O 3 The mass percentage of the carrier is preferably 1-15%, more preferably 5-15%; the Ce is 0.4 Zr 0.6 -γ-Al 2 O 3 Mixing the carrier and the first extraction solvent under stirring; the stirring speed is preferably 600-1500 rpm, more preferablyPreferably 600rpm; the stirring time is preferably 1 to 3 hours, more preferably 3 hours.
In the invention, the M-doped PtPd pseudo-binary alloy nanoparticle aqueous dispersion is added dropwise to Ce 0.4 Zr 0.6 -γ-Al 2 O 3 The Ce is contained in the mixed solution obtained by mixing the carrier and the first extraction solvent 0.4 Zr 0.6 -γ-Al 2 O 3 The mixed solution obtained by mixing the carrier and the first extraction solvent is preferably under stirring; the rate of the dropwise addition is preferably 10 to 60 drops/min, more preferably 10 to 20 drops/min; the stirring speed is preferably 600-1500 rpm, more preferably 600-1000 rpm; the stirring time is preferably 30 to 60 minutes, more preferably 60 minutes; the time for the standing is preferably 6 to 24 hours, more preferably 6 to 12 hours.
The extract phase in the two-phase mixed liquid obtained by the invention contains Ce 0.4 Zr 0.6 -γ-Al 2 O 3 A carrier for attaching the first extraction solvent to Ce by stirring 0.4 Zr 0.6 -γ-Al 2 O 3 The pore channel surface of the carrier, while the M-doped PtPd alloy nano particles are dispersed in the aqueous dispersion, when the aqueous dispersion is dripped into Ce 0.4 Zr 0.6 -γ-Al 2 O 3 When the carrier is mixed with the first extraction solvent to obtain a mixed solution, the M-doped PtPd alloy nano particles replace the first extraction solvent to be loaded on Ce by virtue of the higher surface tension of water and the hydrophilicity of the carrier material 0.4 Zr 0.6 -γ-Al 2 O 3 The surface of the pore canal of the carrier.
After the two-phase mixed solution is obtained, the two-phase mixed solution and the second extraction solvent are mixed, stirred and extracted, and then aged, solid-liquid separated and dried in sequence to obtain the composite dry powder.
In the present invention, the second extraction solvent is chloroform; the volume ratio of the two-phase mixed solution to the second extraction solvent is preferably (1 to 5): 1, more preferably (1 to 3): 1; the aging is preferably performed under a standing condition, and the standing time is preferably 3 to 6 hours, more preferably 3 to 5 hours; the solid-liquid separation is preferably filtration; the drying temperature is preferably 60 to 100 ℃, more preferably 70-90 ℃; the drying time is preferably 6 to 24 hours, more preferably 6 to 12 hours. The invention is adhered to Ce by the second extractant 0.4 Zr 0.6 -γ-Al 2 O 3 The residual first extraction solvent on the surface of the pore canal of the carrier is extracted and displaced to enable the M-doped PtPd alloy nano particles to be more uniformly loaded on Ce 0.4 Zr 0.6 -γ-Al 2 O 3 The surface of the pore canal of the carrier.
In the present invention, the stirring extraction rate is preferably 600 to 1500rpm, more preferably 600 to 1000rpm; the stirring extraction time is preferably 1 to 3 hours, more preferably 2 to 3 hours.
According to the invention, a palladium-based pseudo-binary alloy catalyst with high dispersity is prepared by a multi-solvent extraction method, in the preparation process, an organic solvent n-hexane is filled in a pore passage of a carrier material, and an M-doped PtPd alloy nanoparticle water mixed solution with the same volume as the pore volume of the carrier is added, so that the alloy nanoparticle water mixed solution is dispersed on the surface of the pore passage of the carrier material by utilizing the properties of being insoluble with n-hexane, having larger surface tension of water, being hydrophilic and the like. Because a small amount of n-hexane solution still remains in the pore channels of the carrier material at the moment, uneven dispersion of the alloy nano particles is caused, and therefore, the n-hexane remaining in the pore channels of the carrier material is extracted through chloroform serving as a second extractant, so that the alloy nano particle solution has sufficient space and surface dispersion, and the catalyst with highly dispersed alloy nano particles is obtained.
After the composite dry powder is obtained, the composite dry powder is roasted to obtain the palladium-based pseudo-binary alloy catalyst.
In the present invention, the baking temperature is preferably 400 to 550 ℃, more preferably 450 to 550 ℃, and the holding time is preferably 1 to 3 hours, more preferably 2 to 3 hours.
The invention further improves the interaction between the alloy nano particles and the carrier through roasting, and promotes the oxidation-reduction performance of the active center of the catalyst in the reaction process.
The invention also provides the palladium-based pseudo-binary alloy catalyst prepared by the technical scheme or the palladium prepared by the preparation methodBase pseudo-binary alloy catalyst for catalyzing CH 4 And the use in NO coupling reactions.
In the present invention, the catalytic CH 4 The temperature of the coupling reaction with NO is preferably 400℃or less, more preferably 350 ℃.
The invention catalyzes the CH by the palladium-based pseudo-binary alloy catalyst 4 The mode of application in the NO coupling reaction is not particularly limited, and may be any mode known in the art.
The palladium-based pseudo-binary alloy catalyst provided by the invention is used for catalyzing CH in NGVs tail gas 4 And the coupling reaction of NO is favorable for CH 4 And low-temperature catalytic oxidation of NO (below 400 ℃) to CH 4 And NO has high conversion rate to N 2 Has high selectivity.
The technical solutions of the present invention will be clearly and completely described in conjunction with the embodiments of the present invention, but they should not be construed as limiting the scope of the present invention.
Example 1
Ce (NO) was added at a concentration of 10 wt% 3 ) 3 ˙6H 2 Aqueous O solution with 10wt.% Zr (NO 3 ) 4 Mixing the aqueous solutions, adding ammonia water and ammonium carbonate (molar ratio of 3:3) double-alkali buffer solution to maintain the pH value at 8.8, performing coprecipitation, aging the obtained precipitate at 100 ℃ for 12 hours, sequentially and circularly and repeatedly filtering and washing the obtained material until the obtained filtrate tends to be neutral, drying the obtained material at 120 ℃ for 24 hours, and roasting the obtained powder sample at 600 ℃ for 3 hours to obtain Ce 0.4 Zr 0.6 ；
Al (NO) with a concentration of 10wt.% 3 ) 3 ˙9H 2 O aqueous solution, adding ammonia water and ammonium carbonate (molar ratio 3:3) double-alkali buffer solution to maintain pH value at 8.8, performing coprecipitation to age the obtained precipitate at 100deg.C for 12h, sequentially and circularly filtering and washing the obtained material until the obtained filtrate is neutral, drying the obtained material at 120deg.C for 24h, and roasting the obtained powder sample at 950 deg.C for 3h to obtain gamma-Al 2 O 3 ；
2.44g of Ce prepared as described above 0.4 Zr 0.6 And 2.44g of gamma-Al 2 O 3 Adding into a ball mill, mechanically mixing at 800rmp to obtain Ce 0.4 Zr 0.6 -γ-Al 2 O 3 A carrier material;
0.13g of palladium nitrate, 0.17g of samarium nitrate and 100mL of deionized water are put into a three-necked flask, and mixed by 240W ultrasonic for 30min and stirred at 1000rpm for 1h to obtain a mixed salt solution; mixing the mixed salt solution with 0.003g NaBH 4 Mixing 3g of ethylene glycol, maintaining at 80deg.C under reflux and stirring for 12 hr by double reduction method, filtering, centrifuging at 10000rpm for 30min, and drying at 100deg.C for 12 hr to obtain PdSm nanoparticle (5 nm);
dissolving the PdSm nano particles prepared in the above and 0.03g of platinum acetylacetonate in 10mL of dimethyl diamide, stirring at 1000rpm for 30min, heating to 110 ℃ at 5 ℃/min, continuously reacting for 24h by using an in-situ pyrolysis method, centrifuging at 12000rpm for 30min, and drying at 100 ℃ for 12h to obtain Sm doped PtPd alloy nano particles (5 nm);
dispersing the obtained Sm doped PtPd alloy nano particles in 2.5mL of deionized water, and dropwise adding the obtained Sm doped PtPd alloy nano particles into 4.875gCe under 600rpm at a rate of 10 drops/min 0.4 Zr 0.6 -γ-Al 2 O 3 Stirring the carrier and 60mL of normal hexane at 600rpm for 3 hours to obtain a mixed solution, stirring at 600rpm for 60 minutes, and standing for 6 hours to obtain a two-phase mixed solution;
mixing the prepared two-phase mixed solution with 60mL of chloroform, stirring at 600rpm for 3h, standing for 6h, filtering, and drying at 90 ℃ for 12h to obtain composite dry powder;
roasting the composite dry powder for 3 hours at 550 ℃ to obtain the palladium-based pseudo-binary alloy catalyst (Pt (PdSm)/Ce) 0.4 Zr 0.6 -γ-Al 2 O 3 A catalyst).
Example 2
Ce (NO) was added at a concentration of 10 wt% 3 ) 3 ˙6H 2 Aqueous O solution with 10wt.% Zr (NO 3 ) 4 Mixing the aqueous solutions, adding ammonia water and ammonium carbonate (molar ratio of 3:3) double-alkali buffer solution to maintain pH at 8.8, performing coprecipitation, aging the obtained precipitate at 100deg.C for 12 hr, and collecting the precipitateThe obtained material is sequentially and circularly filtered and washed repeatedly until the obtained filtrate is neutral, the obtained material is dried at 120 ℃ for 24 hours, and the obtained powder sample is roasted at 600 ℃ for 3 hours to obtain Ce 0.4 Zr 0.6 ；
Al (NO) with a concentration of 10wt.% 3 ) 3 ˙9H 2 O aqueous solution, adding ammonia water and ammonium carbonate (molar ratio 3:3) double-alkali buffer solution to maintain pH value at 8.8, performing coprecipitation to age the obtained precipitate at 100deg.C for 12h, sequentially and circularly filtering and washing the obtained material until the obtained filtrate is neutral, drying the obtained material at 120deg.C for 24h, and roasting the obtained powder sample at 950 deg.C for 3h to obtain gamma-Al 2 O 3 ；
2.44g of Ce prepared as described above 0.4 Zr 0.6 And 2.44g of gamma-Al 2 O 3 Adding into a ball mill, mechanically mixing at 800rmp to obtain Ce 0.4 Zr 0.6 -γ-Al 2 O 3 A carrier material;
0.13g of palladium nitrate, 0.13g of indium nitrate and 100mL of deionized water are put into a three-necked flask, and are mixed by 240W ultrasonic for 30min and then stirred for 1h at 1000rpm to obtain a mixed salt solution; mixing the mixed salt solution with 0.003g NaBH 4 Mixing 3g of ethylene glycol, maintaining at 80deg.C under reflux for 12 hr by double reduction, filtering, centrifuging at 10000rpm for 30min, and drying at 100deg.C for 12 hr to obtain PdIn nanoparticle (5 nm);
dissolving the PdIn nano-particles prepared by the method and 0.03g of platinum acetylacetonate In 10mL of dimethyl diamide, stirring at 1000rpm for 30min, heating to 110 ℃ at 5 ℃/min, continuously reacting for 24h by using an In-situ pyrolysis method, centrifuging at 12000rpm for 30min, and drying at 100 ℃ for 12h to obtain In-doped PtPd alloy nano-particles (5 nm);
dispersing the obtained In-doped PtPd alloy nano particles In 2.5mL of deionized water, and dropwise adding the obtained aqueous dispersion of the In-doped PtPd alloy nano particles to 4.875. 4.875gCe under the condition of 600rpm at a rate of 10 drops/min 0.4 Zr 0.6 -γ-Al 2 O 3 The carrier and 60mL of n-hexane were stirred at 600rpm for 3 hours to obtain a mixed solution, and the mixed solution was stirred at 600rpm for 60 minutes and then allowed to stand for 6 hours to obtain a two-phase mixtureA liquid;
mixing the prepared two-phase mixed solution with 60mL of chloroform, stirring at 600rpm for 3h, standing for 6h, filtering, and drying at 90 ℃ for 12h to obtain composite dry powder;
roasting the composite dry powder for 3 hours at 550 ℃ to obtain the palladium-based pseudo-binary alloy catalyst (Pt (PdIn)/Ce) 0.4 Zr 0.6 -γ-Al 2 O 3 A catalyst).
Example 3
Ce (NO) was added at a concentration of 10 wt% 3 ) 3 ˙6H 2 Aqueous O solution with 10wt.% Zr (NO 3 ) 4 Mixing the aqueous solutions, adding ammonia water and ammonium carbonate (molar ratio 3:3) double-alkali buffer solution to maintain the pH value at 8.8, performing coprecipitation to age the obtained precipitate at 100 ℃ for 12 hours, sequentially and circularly filtering and washing the obtained material until the obtained filtrate is neutral, drying the obtained material at 120 ℃ for 24 hours, and roasting the obtained powder sample at 600 ℃ for 3 hours to obtain Ce 0.4 Zr 0.6 ；
Al (NO) with a concentration of 10wt.% 3 ) 3 ˙9H 2 O aqueous solution, adding ammonia water and ammonium carbonate (molar ratio 3:3) double-alkali buffer solution to maintain pH value at 8.8, performing coprecipitation to age the obtained precipitate at 100deg.C for 12h, sequentially and circularly filtering and washing the obtained material until the obtained filtrate is neutral, drying the obtained material at 120deg.C for 24h, and roasting the obtained powder sample at 950 deg.C for 3h to obtain gamma-Al 2 O 3 ；
2.44g of Ce prepared as described above 0.4 Zr 0.6 And 2.44g of gamma-Al 2 O 3 Adding into a ball mill, mechanically mixing at 800rmp to obtain Ce 0.4 Zr 0.6 -γ-Al 2 O 3 A carrier material;
0.13g of palladium nitrate, 0.12g of neodymium nitrate and 100mL of deionized water are put into a three-necked flask, and mixed by 240W ultrasonic for 30min and stirred for 1h at 1000rpm to obtain a mixed salt solution; mixing the mixed salt solution with 0.003g NaBH 4 Mixing with 3g of ethylene glycol, maintaining at 80deg.C under reflux for 12 hr, filtering, centrifuging at 10000rpm for 30min, and drying at 100deg.C for 12 hr to obtain the final productTo PdNd nanoparticles (5 nm);
dissolving the PdND nano-particles prepared in the above and 0.03g of dinitroso diammine platinum in 10mL of dimethyl diamide, stirring at 1000rpm for 30min, heating to 110 ℃ at 5 ℃/min, continuously reacting for 24h by using an in-situ pyrolysis method, centrifuging at 12000rpm for 30min, and drying at 100 ℃ for 12h to obtain Nd-doped PtPd alloy nano-particles (5 nm);
dispersing the obtained Nd-doped PtPd alloy nano particles in 2.5mL of deionized water, and dropwise adding the obtained Nd-doped PtPd alloy nano particles into 4.875gCe under the condition of 600rpm at the speed of 10 drops/min 0.4 Zr 0.6 -γ-Al 2 O 3 Stirring the carrier and 60mL of normal hexane at 600rpm for 3 hours to obtain a mixed solution, stirring at 600rpm for 60 minutes, and standing for 6 hours to obtain a two-phase mixed solution;
mixing the prepared two-phase mixed solution with 60mL of chloroform, stirring at 600rpm for 3h, standing for 6h, filtering, and drying at 90 ℃ for 12h to obtain composite dry powder;
roasting the composite dry powder for 3 hours at 550 ℃ to obtain the palladium-based pseudo-binary alloy catalyst (Pt (PdND)/Ce) 0.4 Zr 0.6 -γ-Al 2 O 3 A catalyst).
Comparative example 1
Ce (NO) was added at a concentration of 10 wt% 3 ) 3 ˙6H 2 Aqueous O solution with 10wt.% Zr (NO 3 ) 4 Mixing the aqueous solutions, adding ammonia water and ammonium carbonate (molar ratio of 3:3) double-alkali buffer solution to maintain the pH value at 8.8, performing coprecipitation, aging the obtained precipitate at 100 ℃ for 12 hours, sequentially and circularly and repeatedly filtering and washing the obtained material until the obtained filtrate tends to be neutral, drying the obtained material at 120 ℃ for 24 hours, and roasting the obtained powder sample at 600 ℃ for 3 hours to obtain Ce 0.4 Zr 0.6 ；
Al (NO) with a concentration of 10wt.% 3 ) 3 ˙9H 2 Adding aqueous solution of O, ammonia water and ammonium carbonate (molar ratio of 3:3) double-alkali buffer solution to maintain pH at 8.8, performing coprecipitation, aging the obtained precipitate at 100deg.C for 12 hr, sequentially and circularly filtering and washing the obtained material until the obtained filtrate is neutral, and collecting the obtained productDrying the material at 120deg.C for 24 hr, and calcining the obtained powder sample at 950 deg.C for 3 hr to obtain gamma-Al 2 O 3 ；
2.44g of Ce prepared as described above 0.4 Zr 0.6 And 2.44g of gamma-Al 2 O 3 Adding into a ball mill, mechanically mixing at 800rmp to obtain Ce 0.4 Zr 0.6 -γ-Al 2 O 3 A carrier material;
in Pd/Ce 0.4 Zr 0.6 -γ-Al 2 O 3 The catalyst is used as a comparative example, and the preparation method specifically comprises the following steps: 0.18g of palladium nitrate and 100mL of deionized water are put into a three-necked flask, and are mixed for 30min by 240W ultrasonic, and then are stirred for 60min at 1000rpm to obtain a salt solution; mixing the mixed salt solution with 0.003g NaBH 4 Mixing 3g of ethylene glycol, and maintaining at 80 ℃ in a condensing reflux state for 12 hours by using a double reduction method to obtain Pd nano particles;
dispersing the prepared Pd nano-particles in 2.5mL of deionized water, and dripping the aqueous dispersion of the obtained Pd nano-particles into 4.875gCe at a rate of 10 drops/min 0.4 Zr 0.6 -γ-Al 2 O 3 Stirring the carrier and 60mL of normal hexane at 600rpm for 3 hours to obtain a mixed solution, stirring at 600rpm for 1 hour, and standing for 6 hours to obtain a two-phase mixed solution;
mixing the prepared two-phase mixed solution with 60mL of chloroform, stirring at 600rpm for 3h, standing for 6h, filtering, and drying at 90 ℃ for 12h to obtain composite dry powder;
roasting the composite dry powder for 3 hours at 550 ℃ to obtain Pd/Ce 0.4 Zr 0.6 -γ-Al 2 O 3 A catalyst.
Performance testing
Pd/Ce prepared in comparative example 1 and palladium-based pseudo-binary alloy catalysts prepared in examples 1 to 3 0.4 Zr 0.6 -γ-Al 2 O 3 Catalyst for catalyzing CH in NGVs tail gas at different temperatures 4 And NO to generate N 2 And test CH 4 And conversion of NO, N 2 The selectivity, specific test conditions (i.e., stoichiometric NGVs simulate exhaust gas) are as follows: 1000ppm CH 4 ，4800ppmCO，960ppmNO，3920ppmO 2 、10vol.％H 2 O，10vol.％CO 2 And N 2 The total gas flow rate was 1680mL/min. The results are shown in fig. 1, 2 and 3, respectively.
As can be seen from FIGS. 1 and 2, the palladium-based pseudo-binary alloy catalysts prepared in examples 1 to 3 can realize CH at 400 ℃ or lower 4 Synchronous and complete conversion with NO, indicating that the catalyst is beneficial for promoting CH 4 Coupling reaction of +no.
As can be seen from FIG. 3, the palladium-based pseudo-binary alloy catalysts prepared in examples 1 to 3 were specific for N 2 The selectivity of (C) reaches 100% at 400 ℃, which is far higher than that of Pd/Ce of comparative example 1 0.4 Zr 0.6 -γ-Al 2 O 3 A catalyst.
Although the foregoing embodiments have been described in some, but not all, embodiments of the invention, according to which one can obtain other embodiments without inventiveness, these embodiments are all within the scope of the invention.
Claims (9)
1. A palladium-based pseudo-binary alloy catalyst is characterized by comprising Ce 0.4 Zr 0.6 -γ-Al 2 O 3 Support and load on the Ce 0.4 Zr 0.6 -γ-Al 2 O 3 M is doped with PtPd pseudo-binary alloy nano particles on the surface of a carrier pore channel, wherein M is Sm, in or Nd;
ce in the palladium-based pseudo-binary alloy catalyst 0.4 Zr 0.6 -γ-Al 2 O 3 The mass percentage of the carrier is 88-99.3%;
the mass percentage of M in the palladium-based pseudo-binary alloy catalyst is 0.5-10%;
the preparation method of the palladium-based pseudo-binary alloy catalyst comprises the following steps:
mixing Pd salt, M salt, a first solvent and a double reducing agent, and then carrying out double reduction reaction to obtain PdM nano particles; m is Sm, in or Nd;
the double reducing agent is NaBH 4 And ethylene glycol;
mixing the PdM nano-particles, organic Pt salt and a second solvent, and performing solvothermal reaction to obtain M-doped PtPd pseudo-binary alloy nano-particles;
dropwise adding the aqueous dispersion of the M-doped PtPd pseudo-binary alloy nano particles into Ce 0.4 Zr 0.6 -γ-Al 2 O 3 Sequentially stirring and standing the mixed solution obtained by mixing the carrier and the first extraction solvent to obtain a two-phase mixed solution;
mixing the two-phase mixed solution with a second extraction solvent, stirring and extracting, and then sequentially aging, solid-liquid separation and drying to obtain composite dry powder;
and roasting the composite dry powder to obtain the palladium-based pseudo-binary alloy catalyst.
2. The palladium-based pseudo-binary alloy catalyst according to claim 1, wherein the Ce 0.4 Zr 0.6 -γ-Al 2 O 3 The carrier comprises Ce 0.4 Zr 0.6 With gamma-Al 2 O 3 The Ce is 0.4 Zr 0.6 With gamma-Al 2 O 3 The mass ratio of (1) to (0.5) is 1.
3. The palladium-based pseudo-binary alloy catalyst according to claim 1, wherein the mass percentage of Pt in the palladium-based pseudo-binary alloy catalyst is 0.1-1%, and the mass percentage of Pd is 0.1-1%.
4. A method for preparing a palladium-based pseudo-binary alloy catalyst according to any one of claims 1 to 3, comprising the steps of:
mixing Pd salt, M salt, a first solvent and a double reducing agent, and then carrying out double reduction reaction to obtain PdM nano particles; m is Sm, in or Nd; the double reducing agent is NaBH 4 And ethylene glycol;
mixing the PdM nano-particles, organic Pt salt and a second solvent, and performing solvothermal reaction to obtain M-doped PtPd pseudo-binary alloy nano-particles;
dropwise adding the aqueous dispersion of the M-doped PtPd pseudo-binary alloy nano particles into Ce 0.4 Zr 0.6 -γ-Al 2 O 3 Sequentially stirring and standing the mixed solution obtained by mixing the carrier and the first extraction solvent to obtain a two-phase mixed solution;
mixing the two-phase mixed solution with a second extraction solvent, stirring and extracting, and then sequentially aging, solid-liquid separation and drying to obtain composite dry powder;
and roasting the composite dry powder to obtain the palladium-based pseudo-binary alloy catalyst.
5. The method according to claim 4, wherein the Pd salt is palladium nitrate; the organic Pt salt is platinum acetylacetonate and/or dinitroso diammine platinum; the M salt is samarium nitrate, neodymium nitrate or indium nitrate.
6. The method of claim 4, wherein the NaBH 4 And ethylene glycol in a mass ratio of (0.001 to 0.1): 1.
7. The process of claim 4 or 5, wherein the first extraction solvent is n-hexane; the second extraction solvent is chloroform.
8. The preparation method according to claim 4, wherein the roasting temperature is 400-550 ℃ and the heat preservation time is 1-3 h.
9. A palladium-based pseudo-binary alloy catalyst according to any one of claims 1 to 3 or a palladium-based pseudo-binary alloy catalyst prepared by the preparation method according to any one of claims 4 to 8 for catalyzing CH 4 And the use in NO coupling reactions.
Priority Applications (1)
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| Publication number | Priority date | Publication date | Assignee | Title |
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| JPH0699068A (en) * | 1992-08-05 | 1994-04-12 | Sekiyu Sangyo Kasseika Center | Catalyst for catalytic reduction of nitrogen oxide |
| KR100638835B1 (en) * | 2005-05-30 | 2006-10-25 | 장길상 | Method for decomposing nitrogen oxides using double reactor |
| CN106606928A (en) * | 2015-10-22 | 2017-05-03 | 中国石油化工股份有限公司 | Denitration method for cracked flue gas produced in production of low-carbon olefin through steam cracking |
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| JP5528323B2 (en) * | 2008-03-19 | 2014-06-25 | ユミコア日本触媒株式会社 | Internal combustion engine exhaust gas purification catalyst and exhaust gas purification method using the catalyst |
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Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0699068A (en) * | 1992-08-05 | 1994-04-12 | Sekiyu Sangyo Kasseika Center | Catalyst for catalytic reduction of nitrogen oxide |
| KR100638835B1 (en) * | 2005-05-30 | 2006-10-25 | 장길상 | Method for decomposing nitrogen oxides using double reactor |
| CN106606928A (en) * | 2015-10-22 | 2017-05-03 | 中国石油化工股份有限公司 | Denitration method for cracked flue gas produced in production of low-carbon olefin through steam cracking |
Non-Patent Citations (1)
| Title |
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| 铈锆固溶体对柴油车氧化型催化剂Pt-Pd/CexZryO2-Al2O3性能的影响;王雨等;金属功能材料;第28卷(第6期);摘要 1 实验部分 * |
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