EP2379207A1 - Purification structure including a catalysis system supported by a zircon in reduced state - Google Patents
Purification structure including a catalysis system supported by a zircon in reduced stateInfo
- Publication number
- EP2379207A1 EP2379207A1 EP09803879A EP09803879A EP2379207A1 EP 2379207 A1 EP2379207 A1 EP 2379207A1 EP 09803879 A EP09803879 A EP 09803879A EP 09803879 A EP09803879 A EP 09803879A EP 2379207 A1 EP2379207 A1 EP 2379207A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- less
- filtration structure
- structure according
- cation
- zirconium oxide
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 230000002829 reductive effect Effects 0.000 title claims abstract description 20
- 238000000746 purification Methods 0.000 title description 6
- 238000006555 catalytic reaction Methods 0.000 title description 3
- 229910052845 zircon Inorganic materials 0.000 title 1
- GFQYVLUOOAAOGM-UHFFFAOYSA-N zirconium(iv) silicate Chemical compound [Zr+4].[O-][Si]([O-])([O-])[O-] GFQYVLUOOAAOGM-UHFFFAOYSA-N 0.000 title 1
- 238000001914 filtration Methods 0.000 claims abstract description 29
- 239000007789 gas Substances 0.000 claims abstract description 27
- 150000001768 cations Chemical class 0.000 claims abstract description 21
- 230000003197 catalytic effect Effects 0.000 claims abstract description 20
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 claims abstract description 18
- 239000002245 particle Substances 0.000 claims abstract description 18
- RVTZCBVAJQQJTK-UHFFFAOYSA-N oxygen(2-);zirconium(4+) Chemical compound [O-2].[O-2].[Zr+4] RVTZCBVAJQQJTK-UHFFFAOYSA-N 0.000 claims abstract description 17
- 229910001928 zirconium oxide Inorganic materials 0.000 claims abstract description 17
- 230000001603 reducing effect Effects 0.000 claims abstract description 12
- 229910052723 transition metal Inorganic materials 0.000 claims abstract description 10
- 239000003344 environmental pollutant Substances 0.000 claims abstract description 8
- 231100000719 pollutant Toxicity 0.000 claims abstract description 8
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 7
- 229910000510 noble metal Inorganic materials 0.000 claims abstract description 7
- 239000001301 oxygen Substances 0.000 claims abstract description 7
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 7
- 150000003624 transition metals Chemical class 0.000 claims abstract description 7
- 239000007787 solid Substances 0.000 claims abstract description 4
- 239000012876 carrier material Substances 0.000 claims abstract 6
- 239000000463 material Substances 0.000 claims description 34
- 239000000203 mixture Substances 0.000 claims description 29
- 238000011282 treatment Methods 0.000 claims description 17
- 239000000843 powder Substances 0.000 claims description 14
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical group [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 claims description 13
- 238000009472 formulation Methods 0.000 claims description 12
- 229910010271 silicon carbide Inorganic materials 0.000 claims description 12
- 238000010438 heat treatment Methods 0.000 claims description 9
- 229910010272 inorganic material Inorganic materials 0.000 claims description 9
- 239000011147 inorganic material Substances 0.000 claims description 9
- 229910002091 carbon monoxide Inorganic materials 0.000 claims description 6
- 229930195733 hydrocarbon Natural products 0.000 claims description 6
- 150000002430 hydrocarbons Chemical class 0.000 claims description 6
- 238000000034 method Methods 0.000 claims description 6
- 239000010970 precious metal Substances 0.000 claims description 5
- 239000004215 Carbon black (E152) Substances 0.000 claims description 4
- 229910052791 calcium Inorganic materials 0.000 claims description 4
- 229910052802 copper Inorganic materials 0.000 claims description 4
- 229910052742 iron Inorganic materials 0.000 claims description 4
- 229910052759 nickel Inorganic materials 0.000 claims description 4
- 238000007254 oxidation reaction Methods 0.000 claims description 4
- 230000010287 polarization Effects 0.000 claims description 4
- 229910052739 hydrogen Inorganic materials 0.000 claims description 3
- 230000003647 oxidation Effects 0.000 claims description 3
- 229910052697 platinum Inorganic materials 0.000 claims description 3
- 230000008569 process Effects 0.000 claims description 3
- 229910000505 Al2TiO5 Inorganic materials 0.000 claims description 2
- 229910052878 cordierite Inorganic materials 0.000 claims description 2
- JSKIRARMQDRGJZ-UHFFFAOYSA-N dimagnesium dioxido-bis[(1-oxido-3-oxo-2,4,6,8,9-pentaoxa-1,3-disila-5,7-dialuminabicyclo[3.3.1]nonan-7-yl)oxy]silane Chemical compound [Mg++].[Mg++].[O-][Si]([O-])(O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2)O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2 JSKIRARMQDRGJZ-UHFFFAOYSA-N 0.000 claims description 2
- 229910052737 gold Inorganic materials 0.000 claims description 2
- 229910052763 palladium Inorganic materials 0.000 claims description 2
- AABBHSMFGKYLKE-SNAWJCMRSA-N propan-2-yl (e)-but-2-enoate Chemical compound C\C=C\C(=O)OC(C)C AABBHSMFGKYLKE-SNAWJCMRSA-N 0.000 claims description 2
- 229910052703 rhodium Inorganic materials 0.000 claims description 2
- 229910052709 silver Inorganic materials 0.000 claims description 2
- 229910000314 transition metal oxide Inorganic materials 0.000 claims description 2
- 229910003465 moissanite Inorganic materials 0.000 claims 1
- 230000007704 transition Effects 0.000 claims 1
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 46
- 239000003054 catalyst Substances 0.000 description 19
- 238000006722 reduction reaction Methods 0.000 description 17
- 230000009467 reduction Effects 0.000 description 16
- QVQLCTNNEUAWMS-UHFFFAOYSA-N barium oxide Chemical compound [Ba]=O QVQLCTNNEUAWMS-UHFFFAOYSA-N 0.000 description 8
- 239000000446 fuel Substances 0.000 description 6
- 239000000243 solution Substances 0.000 description 6
- -1 transition metal cations Chemical class 0.000 description 6
- 239000007864 aqueous solution Substances 0.000 description 5
- 229910052788 barium Inorganic materials 0.000 description 5
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 5
- 238000006243 chemical reaction Methods 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- 230000008901 benefit Effects 0.000 description 4
- 238000005470 impregnation Methods 0.000 description 4
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Substances [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 4
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical group [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 3
- 229910000287 alkaline earth metal oxide Inorganic materials 0.000 description 3
- 238000001354 calcination Methods 0.000 description 3
- 230000008021 deposition Effects 0.000 description 3
- 230000000694 effects Effects 0.000 description 3
- 230000007935 neutral effect Effects 0.000 description 3
- 238000003860 storage Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 229910052815 sulfur oxide Inorganic materials 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 2
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- QQONPFPTGQHPMA-UHFFFAOYSA-N Propene Chemical compound CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 description 2
- 239000003513 alkali Substances 0.000 description 2
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- 238000001125 extrusion Methods 0.000 description 2
- 238000001033 granulometry Methods 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- KDLHZDBZIXYQEI-UHFFFAOYSA-N palladium Substances [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 2
- 239000010948 rhodium Substances 0.000 description 2
- 239000010944 silver (metal) Substances 0.000 description 2
- XTQHKBHJIVJGKJ-UHFFFAOYSA-N sulfur monoxide Chemical class S=O XTQHKBHJIVJGKJ-UHFFFAOYSA-N 0.000 description 2
- 229910052727 yttrium Inorganic materials 0.000 description 2
- VWQVUPCCIRVNHF-UHFFFAOYSA-N yttrium atom Chemical compound [Y] VWQVUPCCIRVNHF-UHFFFAOYSA-N 0.000 description 2
- 229910052684 Cerium Inorganic materials 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- 229910020599 Co 3 O 4 Inorganic materials 0.000 description 1
- 229910052688 Gadolinium Inorganic materials 0.000 description 1
- 229910016006 MoSi Inorganic materials 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 238000007792 addition Methods 0.000 description 1
- 150000001342 alkaline earth metals Chemical class 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
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 239000007900 aqueous suspension Substances 0.000 description 1
- 239000011230 binding agent Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 238000010531 catalytic reduction reaction Methods 0.000 description 1
- 229920002678 cellulose Polymers 0.000 description 1
- 239000001913 cellulose Substances 0.000 description 1
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 1
- 229910000420 cerium oxide Inorganic materials 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 230000006735 deficit Effects 0.000 description 1
- 238000005137 deposition process Methods 0.000 description 1
- 238000003795 desorption Methods 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000005518 electrochemistry Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- UIWYJDYFSGRHKR-UHFFFAOYSA-N gadolinium atom Chemical compound [Gd] UIWYJDYFSGRHKR-UHFFFAOYSA-N 0.000 description 1
- 238000004868 gas analysis Methods 0.000 description 1
- 239000010931 gold Substances 0.000 description 1
- 229910001385 heavy metal Inorganic materials 0.000 description 1
- 239000011499 joint compound Substances 0.000 description 1
- 229910052746 lanthanum Inorganic materials 0.000 description 1
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000010534 mechanism of action Effects 0.000 description 1
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 1
- 229910052753 mercury Inorganic materials 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 description 1
- SIWVEOZUMHYXCS-UHFFFAOYSA-N oxo(oxoyttriooxy)yttrium Chemical compound O=[Y]O[Y]=O SIWVEOZUMHYXCS-UHFFFAOYSA-N 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 239000003361 porogen Substances 0.000 description 1
- 238000002459 porosimetry Methods 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 239000001294 propane Substances 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 150000002910 rare earth metals Chemical class 0.000 description 1
- 230000007420 reactivation Effects 0.000 description 1
- 238000009877 rendering Methods 0.000 description 1
- 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 1
- 239000007320 rich medium Substances 0.000 description 1
- 229910021332 silicide Inorganic materials 0.000 description 1
- FVBUAEGBCNSCDD-UHFFFAOYSA-N silicide(4-) Chemical compound [Si-4] FVBUAEGBCNSCDD-UHFFFAOYSA-N 0.000 description 1
- 238000005245 sintering Methods 0.000 description 1
- 230000006641 stabilisation Effects 0.000 description 1
- 238000011105 stabilization Methods 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
- B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/56—Platinum group metals
- B01J23/58—Platinum group metals with alkali- or alkaline earth metals
-
- 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
- B01D53/9445—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC]
- B01D53/945—Simultaneously removing carbon monoxide, hydrocarbons or nitrogen oxides making use of three-way catalysts [TWC] or four-way-catalysts [FWC] characterised by a specific catalyst
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
- B01J23/54—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/56—Platinum group metals
- B01J23/63—Platinum group metals with rare earths or actinides
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
- B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/78—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with alkali- or alkaline earth metals
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
- B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/83—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with rare earths or actinides
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
- B01J23/89—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals
- B01J23/8933—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals also combined with metals, or metal oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/894—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals also combined with metals, or metal oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with rare earths or actinides
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
- B01J23/89—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals
- B01J23/8933—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals also combined with metals, or metal oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
- B01J23/8946—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with noble metals also combined with metals, or metal oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with alkali or alkaline earth metals
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/16—Reducing
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
- C04B38/0006—Honeycomb structures
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2255/00—Catalysts
- B01D2255/10—Noble metals or compounds thereof
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2255/00—Catalysts
- B01D2255/20—Metals or compounds thereof
- B01D2255/207—Transition metals
- B01D2255/20715—Zirconium
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D2258/00—Sources of waste gases
- B01D2258/01—Engine exhaust gases
- B01D2258/012—Diesel engines and lean burn gasoline engines
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/30—Catalysts, in general, characterised by their form or physical properties characterised by their physical properties
- B01J35/33—Electric or magnetic properties
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/50—Catalysts, in general, characterised by their form or physical properties characterised by their shape or configuration
- B01J35/56—Foraminous structures having flow-through passages or channels, e.g. grids or three-dimensional monoliths
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J35/00—Catalysts, in general, characterised by their form or physical properties
- B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
- B01J35/61—Surface area
- B01J35/612—Surface area less than 10 m2/g
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
- B01J37/34—Irradiation by, or application of, electric, magnetic or wave energy, e.g. ultrasonic waves ; Ionic sputtering; Flame or plasma spraying; Particle radiation
- B01J37/348—Electrochemical processes, e.g. electrochemical deposition or anodisation
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/12—Improving ICE efficiencies
Definitions
- the present invention relates to the field of structures for purifying a gas charged with gaseous pollutants essentially of NO x type. More particularly, the invention relates to honeycomb structures, in particular used to treat the exhaust gas of a diesel engine, and incorporating a catalytic system for the depollution of said polluting species.
- a conventional three-way catalyst allows the joint treatment of pollutants NO x , CO and HC and their conversion into neutral and chemically harmless gases such as N 2 , CO 2 and H 2 O.
- a very good efficiency of the system is not achieved only by a continuous adjustment of the richness of the air-fuel mixture. It is thus known that the slightest deviation from the stoichiometry of said mixture causes a large increase in pollutant emissions.
- the materials used to adsorb NOx are most often alkali or alkaline earth metal oxides, in particular barium oxide, which is today considered to be the most effective material in this domain.
- barium oxide which is today considered to be the most effective material in this domain.
- SOx sulfur oxides
- the precursors of barium being difficult to disperse on the support material, it is necessary to provide significant amounts. This leads to reducing the accessibility of the noble metals of the catalytic system by a "covering" effect by barium oxide. A possible but too expensive solution would be to increase the contribution of noble metals in the system.
- these barium-based NOx trap systems pose hygiene and environmental problems, barium being listed as heavy metal.
- NOx reduction systems incorporating a zirconia type support material are also known, but these systems are not very efficient.
- a Zirconia can be used as catalyst support in 3-way NOx reduction systems.
- the zirconia employed described in this publication is a zirconia stabilized by Yttrium doping possibly comprising additions of cerium oxide or Lanthanum. In such systems, zirconia serves only to support the catalyst but does not allow storage of NOx.
- the object of the present invention is to provide a solution for solving the problems described above, in particular with regard to the NOx storage function.
- one of the aims of the present invention is to provide a structure for the purification of a polluted gas, in particular a structure for filtering an exhaust gas resulting from a diesel engine loaded with gaseous and particulate pollutants.
- solid capable of functioning in the absence of specific NOx traps based on oxides of alkali or alkaline earth metals, in particular barium.
- the invention consists of a filtration structure of a gas resulting from a diesel engine, charged with gaseous pollutants of the NO x nitrogen oxide type and solid particles, of the particulate filter type, said structure comprising a set longitudinal adjacent channels of axes parallel to each other separated by porous filtering walls constituted by said porous inorganic material, said channels being alternately plugged at one or the other end of the structure to define inlet channels and outlet channels for the gas to be filtered, and to force said gas to pass through the porous walls separating the inlet and outlet channels, said filtration structure being characterized by it comprises a catalytic system comprising at least one noble or transition metal suitable for the reduction of NOx and a support material, wherein said support material comprises or consists of a zirconium oxide partially substituted with a trivalent cation M 3+ or by a divalent cation M ' 2+ , said zirconium oxide being in a reduced state, under stoichiometric oxygen.
- the catalytic system is advantageously chosen to also be suitable for the oxidation of polluting species of the HC, CO or H 2 hydrocarbon type.
- a catalytic system comprises at least one precious metal selected from Pt and / or Pd and / or Rh and / or Ag and / or Au and / or transition metals, in particular Cu, Fe, Ni, Co , and transition metal oxides such as Mn 2 ⁇ 3 , Co 3 O 4 .
- the support material corresponds to the formulation (Zr ⁇ 2- X) i- y (M 2 ⁇ 3- X) y, M being a cation of valency 3 preferably selected from the group consisting of Y 3+, Sc 3+, or rare earths and being strictly greater than 0 and preferably less than 2.
- y is less than or equal to 0.5, more preferably y is less than or equal to 0.25, and most preferably y is less than or equal to 0.1.
- the support material corresponds to the formulation (ZrO 2 -x) iy ' (M'Oi x ) y' , M 'being a cation of valence 2 preferably chosen from the group consisting of Ca 2+ and Sr 2+ and y 'being strictly greater than 0 and strictly less than 2.
- y ' is less than 0.6, more preferably y' is less than 0.3, and most preferably y 'is less than or equal to 0.15.
- the reduced filtration structure according to the invention is such that x is less than 0.5, preferably less than 0.1, and very preferably less than 0.05.
- x is greater than 0.005, preferably greater than 0.01.
- This support material of the catalytic system based on zirconia according to the invention preferably has, even after a calcination of 800 and 1000 0 C, a specific surface area of at least 5 m 2 / g, preferably at least 10 m 2 / g, or even at least 50 m 2 / g.
- the zirconia forming all or part of the support material can be obtained by different doping by substituting the zirconium atoms with lower valence transition metal cations such as Y 3+ , Sc 3+ , Ca 2+ , Sr 2+ or rare earth.
- the ionic conductivity is preferably between 1 and 10 -4 S / cm in the temperature range from 150 to 800 ° C.
- the porous inorganic material has an open porosity, conventionally measured by mercury porosimetry, greater than 10%, preferably greater than 20%, or even greater than 30%. Too little porosity of the material constituting the filtering walls leads to a too high pressure drop.
- the porous inorganic material comprises or consists of an electrically conductive inorganic material of the carbide type, for example SiC, or a silicide, for example MoSi 2 or boride, for example TiB 2 , or of the Lai x Sr x MnO 3 family. or mixed oxides of gadolinium and cerium (CGO).
- an electrically conductive inorganic material of the carbide type for example SiC
- a silicide for example MoSi 2 or boride, for example TiB 2 , or of the Lai x Sr x MnO 3 family. or mixed oxides of gadolinium and cerium (CGO).
- the porous inorganic material is based on silicon carbide SiC, preferably recrystallized at a temperature of between 2100 and 2400 ° C.
- the inorganic material may be based on doped SiC, for example with aluminum or nitrogen, and such that its electronic resistivity is preferably lower than 20 Ohm. cm, more preferably at 15 Ohm. cm, more preferably 10 Ohm. cm at 400 ° C.
- SiC-based is meant in the sense of the present description that the material consists of at least 25% by weight, preferably at least 45% by weight and so very preferred at least 70% by weight of SiC.
- the porous inorganic material is based on Cordierite or Aluminum Titanate.
- the invention relates to a powder that can be used as a support material in a filtration structure as previously described, said powder comprising particles of zirconium oxide partially substituted by a cation M or M ', free of metal precious metals of the Pt, Pd, Rh, Ag, Au and transition metal type, in particular Cu, Fe, Ni, Co, said substituted zirconium oxide being in the reduced state, under stoichiometric oxygen and corresponding to the formulation (ZrO 2 - X) i- y (M 2 ⁇ 3_ x) y, M being a cation of valency 3 preferably selected from the group consisting of Y 3+, Sc 3+, or rare earths and being strictly greater than 0 and strictly less at 2 or responding to the formulation
- the reduced state of the partially substituted zirconium oxide can be obtained by a heat treatment at a temperature above 400 ° C. under a reducing atmosphere or by an electrochemical treatment consisting of the polarization of the material by application of a voltage or bias current thereon.
- a powder as described above is advantageous as support material for an NO x reduction catalyst, in a particulate filter type filter structure as previously described.
- the powder makes it possible, in particular, to obtain a catalytic system such as has been previously described, characterized in particular by comprising at least one noble or transition metal suitable for the reduction of NO x and said support material. as previously described, comprising or consisting of zirconium oxide in a reduced state partially substituted by a trivalent M 3+ or divalent M ' 2+ cation.
- the catalyst used would allow a selective oxidation reaction of NOx to NO2.
- the NO2 would then, surprisingly and never before, be captured at the catalyst support in a ZrO (NO 2 ) form. Such a phenomenon would occur in particular during the operating phases of the lean fuel engine.
- the catalyst used would also allow, during subsequent phases, the NOx reduction reaction (NO and NO2) in N2, in particular during the engine operating phases in fuel-rich mixture, that is to say say in a reducing atmosphere.
- NO and NO2 NOx reduction reaction
- the tests carried out by the applicant have indeed shown that during such phases, the zirconia-based carrier would release the nitrogen oxides previously stored. Without being considered definitive, the proposed mechanism could be as follows:
- the metal catalysts can be deposited in a conventional manner by impregnation with the surface of a zirconia powder as described according to the invention, for example by processes such as those described in particular by US5884473.
- the introduction of the catalytic system whose support material acts as a NOx trap advantageously makes it possible to greatly increase the catalyst surface area accessible to the pollutants, and consequently the probability of contact and exchanges between the reactive species,
- the support material constituted according to the invention also has a high thermal stability with respect to alumina-type support materials, in particular because of a better sintering resistance of the metal catalyst particles deposited in contact with the oxygen vacancies of the material support, - the support material formed according to the invention has a high reactivation in a fuel-rich medium compared to previous solutions.
- the catalytic system according to the invention not comprising barium is therefore much less sensitive to the presence of sulfur oxides (SO x ) in the gases to be treated.
- the present invention is particularly applicable in the filter wall structures used for purification and the most effective for filtering an exhaust gas from a diesel engine.
- Such structures generally referred to as particle filters, comprise at least one and preferably a plurality of monolithic honeycomb blocks joined by a joint cement.
- the block or blocks comprising a set of adjacent ducts or channels of axes parallel to each other separated by porous walls, closed by plugs to one or the other. other of their ends to define inlet ducts opening on a gas inlet face and outlet ducts opening on a gas evacuation face, so that the gas passes through the porous walls.
- Examples of such assembled or unassembled structures are for example described in EP 0816065, EP 1142619, EP1306358 or EP 1591430.
- the porous inorganic structure is impregnated with an aqueous solution comprising zirconia particles having the characteristics according to the invention, that is to say that the support is a reduced zirconium oxide corresponding to the formulations (Zr ⁇ 2- X) iy (M 2 ⁇ 3_ x) y or (ZrO 2 - x) y '(me IM-x) y', wherein M is a cation of valence 3 and M 'is a cation of valency 2 .
- said substituted zirconia type support is in a form reduced, that is to say that it has undergone a reduction treatment having brought it in a deficit state (or stoichiometric) oxygen
- said reduction treatment can be chosen according to the invention among all known treatments for this purpose and in particular by heating in a reducing atmosphere, by electrochemistry, etc.
- the reduced state of the support can be obtained in particular by a reduction treatment by thermal means that is to say by a high temperature treatment, for example between 400 and 1000 0 C, under a reducing atmosphere.
- the reduction treatment can also be carried out under a reducing atmosphere of light hydrocarbon such as for example methane, propane, propene or carbon monoxide CO, in a temperature range between 400 and 1000 ° C.
- the duration heat treatment can be adapted to the starting granulometry and / or the specific surface of the powder intended for the deposition on the structure and / or the temperature. This duration is in general at least equal to 10 minutes and preferably greater than or equal to 60 minutes.
- the reduction treatment is carried out in a step prior to the impregnation of the structure with the substituted zirconia particles.
- the structure comprising the support in the reduced state is then impregnated in one or more steps by the catalytic system (s) necessary for the conversion of NO x to N 2 .
- the porous inorganic structure is this time first impregnated with an aqueous solution comprising doped zirconia particles by substituting the zirconium atoms with lower valence transition metal cations (3 or 4). 2) such as Y 3+ , Sc 3+ , Ca 2+ , Sr 2+ or rare earths to ultimately obtain a material of the previously described formulation.
- the heat reduction treatment is performed this time on the structure impregnated with the support material, ie after the deposition of the zirconia.
- the reduction treatment can be carried out under the same conditions as those already described in the previous mode.
- the structure is impregnated in one or more steps by the catalytic system (s) necessary for the conversion of NO x to N 2 .
- This second embodiment has the advantage of permitting the impregnation of the porous structure under conditions that are not necessarily reducing, for example under air.
- the porous inorganic structure is impregnated with an aqueous solution comprising doped zirconia particles by substituting the zirconium atoms with lower valence (3 or 2) transition metal cations such as Y 3+ , Sc 3+ , Ca 2+ , Sr 2+ or rare earths to ultimately obtain a material of the previously described formulation.
- the structure is impregnated in one or more steps by the catalytic system or systems to the conversion of NO x to N 2 .
- the catalysts and the zirconia are deposited at the same time on the structure.
- the thermal reduction treatment which may be of the same type as that previously described, is carried out on the structure already impregnated by the catalyst and its support material.
- This third embodiment makes it possible to carry out the heat treatment at a lower temperature, typically at a temperature between 400 and 600 ° C., because of the reducing activity of the catalytic metals.
- the reduced state of the partially substituted zirconium oxide can also be obtained according to the invention by an electrochemical treatment consisting of the polarization of the material by applying a voltage or a polarization current thereon. .
- cylindrical honeycomb monoliths of recrystallized silicon carbide (SiC) cylindrical shape have been synthesized according to the conventional techniques already well known in the art and for example described in patent application EP 1 142 619 A1.
- a mixture of silicon carbide particles with a purity greater than 98% was first produced in a kneader in accordance with the method of manufacturing an R-SiC structure described in application WO 1994/22556.
- the mixture is obtained from a coarse fraction of SiC particles (75% by weight) whose median particle diameter is greater than 10 microns and a fraction of fine granulometry (25% weight) with a median particle size of less than 1 micron.
- the median diameter refers to the diameter of the particles below which 50% by mass of the population is found.
- Water is also added up to 20% by weight of the sum of the preceding constituents and kneaded to obtain a homogeneous paste whose plasticity allows the formation of monoliths or the extrusion through a die of a structure honeycomb.
- the recrystallized SiC honeycomb monoliths are dried deliantes, corked and fired under a neutral atmosphere at a temperature of 2200 ° C.
- the optimal experimental conditions are as follows: rise in temperature of 20 ° C. / hour up to 2200 0 C then temperature plateau of 6 hours at 2200 0 C.
- the monoliths are immersed in an embodiment similar to that described in US Pat. No. 5,866,210 in this solution so as to impregnate about 1.5% by weight of zirconia doped with respect to the monolith. Drying is carried out at 40 ° C. and then calcination at 500 ° C. under air is carried out at a heating rate of 100 ° C./h and a plateau at the maximum temperature of one hour.
- the monolith is impregnated with an aqueous solution of platinum dinitrodiamine chloride.
- the monolith is dried at 40 ° C. and then calcined at 500 ° C. in air, according to a heating rate of 100 ° C./hour and a plateau at the maximum temperature of one hour.
- the monolith is impregnated with an aqueous solution of Rhodium nitrate, the monolith is then dried at 40 ° C. and then calcined to 500 ° C. under air, with a heating rate of 100 ° C./h, with a bearing at the maximum temperature of one hour.
- the concentration of precious metal solutions and the deposition process are adapted to constitute catalysed monoliths whose chemical analysis shows the following characteristics:
- Example 1 The experimental protocol already described in Example 1 was entirely taken up in this example, except that this second series of monoliths underwent after impregnation of the supported catalyst additional reduction treatment in pure H 2 at 600 0 C for 1 hour.
- the analyzes have shown that the zirconia substituted and reduced substantially corresponded to the formulation (Zr ⁇ 2- X) i- y (M 2 ⁇ 3_ x) y, wherein y is about 0.08 and x is close to 0.02 .
- the test is carried out as follows: The mixture of lean gas 1 passes first on the catalysed monolith maintained in an electric oven at 250 or 300 ° C.
- the composition of the gases passing through the monolith is alternated according to the following protocol: first mixture 1 for 3 minutes and then rocking to the gas mixture 2 (rich) for 2 minutes, then to mixture 1 (3 minutes) and so on.
- the composition of the gases at the furnace outlet is analyzed after stabilization of the system so as to know the amount of NO x converted into N 2 .
- the test as just described was carried out under the same conditions for each temperature 250 and 300 ° C. on the monolith according to Example 1 (unreduced zirconia) and on the monolith according to Example 2 (zirconia). scaled down) .
- the gas flow rate is 10 1 / h for both mixtures.
- Thermocouple type temperature sensors are placed about 5mm from the exit surface of the monolith.
- the gas analysis is performed at the outlet of the reactor by IR and ⁇ GC
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Abstract
The invention relates to a structure for filtering a gas emitted by a diesel engine and laden with gaseous pollutants such as nitrogen oxides NOx and solid particles, such as a particle filter, characterised in that said filtering structure includes a catalytic system including at least one noble or transition metal suitable for reducing NOx and a carrier material, wherein said carrier material includes or is made of zirconium oxide partially substituted by a trivalent cation M3+ or by a divalent cation M'2+, said zirconium oxide being in a reduced state, with a sub-stoichiometric oxygen content.
Description
STRUCTURE DE PURIFICATION INCORPORANT UN SYSTEME DE CATALYSE SUPPORTE PAR UNE ZIRCONE A L'ETAT REDUIT PURIFICATION STRUCTURE INCORPORATING A CATALYSIS SYSTEM SUPPORTED BY A REDUCED ZIRCONY
La présente invention se rapporte au domaine des structures de purification d'un gaz chargé en polluants gazeux essentiellement du type NOx. Plus particulièrement, l'invention se rapporte aux structures en nid d'abeille, notamment utilisées pour traiter les gaz d'échappement d'un moteur diesel, et incorporant un système catalytique de dépollution desdites espèces polluantes.The present invention relates to the field of structures for purifying a gas charged with gaseous pollutants essentially of NO x type. More particularly, the invention relates to honeycomb structures, in particular used to treat the exhaust gas of a diesel engine, and incorporating a catalytic system for the depollution of said polluting species.
Les techniques et les problèmes liés à la purification des gaz pollués, notamment en sortie des lignes d'échappement des véhicules automobiles essence ou diesel sont bien connus de l'art. Un catalyseur conventionnel trois voies permet le traitement conjoint des polluants NOx, CO et HC et leur conversion en des gaz neutres et chimiquement non nocifs tels que N2, CO2 et H2O. Une très bonne efficacité du système n'est cependant atteinte que par un réglage continuel de la richesse du mélange air- carburant. Il est ainsi connu que le moindre écart par rapport à la stoechiométrie dudit mélange provoque une forte augmentation des émissions des polluants. Pour résoudre ce problème, il est nécessaire d' incorporer au catalyseur des matériaux permettant temporairement de fixer les NOx (souvent appelés dans le métier NOx trap) lorsque le mélange air/carburant est pauvre (c'est à dire sous stoechiométrique en carburant) . La désorption des NOx piégés sur le catalyseur et leur réduction catalytique en azote gazeux N2 sont obtenues en présence, au niveau du catalyseur permettant la réduction, d'une quantité suffisante des espèces réductrices sous forme d'hydrocarbures ou de monoxyde de carbone CO ou
d'hydrogène gazeux H2, l'hydrogène gazeux pouvant être lui- même obtenu par une réaction catalytique entre les hydrocarbures HC et la vapeur d'eau et/ou le dioxyde de carbone ou entre le CO et la vapeur d'eau. A l'heure actuelle, les matériaux utilisés pour adsorber les NOx sont le plus souvent des oxydes de métaux alcalins ou d' alcalino-terreux, en particulier d'oxyde de Baryum, qui est aujourd'hui considéré comme le matériau le plus efficace dans ce domaine. Ces solutions posent cependant un problème de stabilité chimique car la fonction « NOx-trap » de l'oxyde de Baryum est rapidement empoisonnée par les oxydes de soufre (SOx) également contenus dans les gaz d'échappement, notamment de moteur Diesel. Par ailleurs, les précurseurs du Baryum étant difficiles à disperser sur le matériau support, il est nécessaire d'en apporter des quantités importantes. Ceci conduit à réduire l'accessibilité des métaux nobles du système catalytique par un effet de « couverture » par l'oxyde de Baryum. Une solution possible mais trop onéreuse consisterait à augmenter l'apport de métaux nobles dans le système. En outre, ces systèmes de piège à NOx à base de Baryum posent des problèmes d'hygiène et d'environnement, le Baryum étant répertorié comme métal lourd.The techniques and problems related to the purification of polluted gases, especially at the outlet of the exhaust lines of gasoline or diesel motor vehicles are well known in the art. A conventional three-way catalyst allows the joint treatment of pollutants NO x , CO and HC and their conversion into neutral and chemically harmless gases such as N 2 , CO 2 and H 2 O. A very good efficiency of the system is not achieved only by a continuous adjustment of the richness of the air-fuel mixture. It is thus known that the slightest deviation from the stoichiometry of said mixture causes a large increase in pollutant emissions. To solve this problem, it is necessary to incorporate into the catalyst materials allowing temporarily to fix the NO x (often called in the NO x trap trade) when the air / fuel mixture is poor (that is to say under stoichiometric fuel ). The desorption of NOx entrapped on the catalyst and their catalytic reduction in nitrogen gas N 2 are obtained in the presence, at the level of the catalyst allowing the reduction, of a sufficient quantity of reducing species in the form of hydrocarbons or carbon monoxide CO or hydrogen gas H 2 , hydrogen gas being itself obtainable by a catalytic reaction between HC hydrocarbons and water vapor and / or carbon dioxide or between CO and water vapor. At present, the materials used to adsorb NOx are most often alkali or alkaline earth metal oxides, in particular barium oxide, which is today considered to be the most effective material in this domain. These solutions, however, pose a problem of chemical stability because the "NOx-trap" function of barium oxide is rapidly poisoned by the sulfur oxides (SOx) also contained in the exhaust gases, in particular diesel engines. Moreover, the precursors of barium being difficult to disperse on the support material, it is necessary to provide significant amounts. This leads to reducing the accessibility of the noble metals of the catalytic system by a "covering" effect by barium oxide. A possible but too expensive solution would be to increase the contribution of noble metals in the system. In addition, these barium-based NOx trap systems pose hygiene and environmental problems, barium being listed as heavy metal.
On connaît des systèmes alternatifs de réduction des NOx utilisant un support d' alumine de grande surface spécifique. Ce type de support n'est cependant pas utilisable dans une telle application, du fait de sa stabilité thermique insuffisante.Alternative NOx reduction systems are known using a high surface area alumina support. This type of support is however not usable in such an application, because of its insufficient thermal stability.
On connaît également des systèmes de réduction des NOx incorporant un matériau support de type zircone mais ces systèmes sont peu performants. Ainsi, de façon connue, par exemple tel qu'illustrée par le brevet US5232890, une
zircone peut être utilisée comme support du catalyseur dans des systèmes 3 voies de réduction des NOx. La zircone employée décrite dans cette publication est une zircone stabilisée par dopage à l'Yttrium comportant éventuellement des additions d'oxyde de Cérium ou de Lanthane. Dans de tels systèmes, la zircone sert uniquement de support du catalyseur mais ne permet pas de stockage des NOx.NOx reduction systems incorporating a zirconia type support material are also known, but these systems are not very efficient. Thus, in known manner, for example as illustrated by the patent US5232890, a Zirconia can be used as catalyst support in 3-way NOx reduction systems. The zirconia employed described in this publication is a zirconia stabilized by Yttrium doping possibly comprising additions of cerium oxide or Lanthanum. In such systems, zirconia serves only to support the catalyst but does not allow storage of NOx.
Dans les documents publics concernant ce sujet, il est communément indiqué qu'il est nécessaire au bon fonctionnement d'un tel système de faire intervenir en plus des matériaux à base d'oxyde de métaux alcalins ou alcalino-terreux, en général de l'oxyde de Baryum servant de piège à NOx.In the public documents relating to this subject, it is commonly stated that it is necessary for the proper functioning of such a system to involve, in addition to materials based on alkaline or alkaline earth metal oxide, generally Barium oxide as a NOx trap.
Le but de la présente invention est de fournir une solution permettant de résoudre les problèmes précédemment décrits, en particulier en ce qui concerne la fonction de stockage des NOx. En particulier, un des buts de la présente invention est de fournir une structure pour la purification d'un gaz pollué, en particulier une structure de filtration d'un gaz d'échappement issu d'un moteur diesel chargé en polluants gazeux et en particules solides, susceptible de fonctionner en l'absence de pièges à NOx spécifique à base d'oxydes de métaux alcalins ou alcalino- terreux, en particulier de Baryum.The object of the present invention is to provide a solution for solving the problems described above, in particular with regard to the NOx storage function. In particular, one of the aims of the present invention is to provide a structure for the purification of a polluted gas, in particular a structure for filtering an exhaust gas resulting from a diesel engine loaded with gaseous and particulate pollutants. solid, capable of functioning in the absence of specific NOx traps based on oxides of alkali or alkaline earth metals, in particular barium.
Plus précisément l'invention consiste en une structure de filtration d'un gaz issu d'un moteur diesel, chargé en polluants gazeux du type oxydes d'azote NOx et en particules solides, du type filtre à particules, ladite structure comprenant un ensemble de canaux adjacents longitudinaux d'axes parallèles entre eux séparés par des parois poreuses filtrantes constituées par ledit matériau inorganique poreux, lesdits canaux étant alternativement bouchés à l'une ou l'autre des extrémités de la structure
de façon à définir des canaux d'entrée et des canaux de sortie pour le gaz à filtrer, et de façon à forcer ledit gaz à traverser les parois poreuses séparant les canaux d'entrée et de sortie, ladite structure de filtration se caractérisant en ce qu'elle comprend un système catalytique comprenant au moins un métal noble ou de transition convenant pour la réduction des NOx et un matériau support, dans lequel ledit matériau support comprend ou est constitué par un oxyde de zirconium partiellement substitué par un cation trivalent M3+ ou par un cation divalent M'2+, ledit oxyde de zirconium étant dans un état réduit, sous stœchiométrique en oxygène.More specifically, the invention consists of a filtration structure of a gas resulting from a diesel engine, charged with gaseous pollutants of the NO x nitrogen oxide type and solid particles, of the particulate filter type, said structure comprising a set longitudinal adjacent channels of axes parallel to each other separated by porous filtering walls constituted by said porous inorganic material, said channels being alternately plugged at one or the other end of the structure to define inlet channels and outlet channels for the gas to be filtered, and to force said gas to pass through the porous walls separating the inlet and outlet channels, said filtration structure being characterized by it comprises a catalytic system comprising at least one noble or transition metal suitable for the reduction of NOx and a support material, wherein said support material comprises or consists of a zirconium oxide partially substituted with a trivalent cation M 3+ or by a divalent cation M ' 2+ , said zirconium oxide being in a reduced state, under stoichiometric oxygen.
Ainsi, si dans les documents cités précédemment, il était déjà mentionné l'utilisation d'une zircone partiellement substituée par des cations de valence inférieure, par exemple des cations d' Yttrium Y3+, aucun traitement préalable particulier d'un tel matériau n'est mentionné, dans le but de le rendre apte à piéger efficacement les oxydes d'azote NOx, dans une telle structure de filtration.Thus, if in the documents cited above, it was already mentioned the use of a zirconia partially substituted by lower valence cations, for example yttrium Y 3+ cations, no particular pretreatment of such a material is mentioned, with the aim of rendering it capable of effectively trapping nitrogen oxides NOx, in such a filtration structure.
En outre, le système catalytique est avantageusement choisi pour convenir également à l'oxydation des espèces polluantes du type hydrocarbures HC, CO ou H2. Sans y être limité, un tel système catalytique comprend au moins un métal précieux choisi parmi Pt et/ou Pd et/ou Rh et/ou Ag et/ou Au et/ou les métaux de transition, notamment Cu, Fe, Ni, Co, et les oxydes de métaux de transition comme Mn2θ3, Co3O4.In addition, the catalytic system is advantageously chosen to also be suitable for the oxidation of polluting species of the HC, CO or H 2 hydrocarbon type. Without being limited thereto, such a catalytic system comprises at least one precious metal selected from Pt and / or Pd and / or Rh and / or Ag and / or Au and / or transition metals, in particular Cu, Fe, Ni, Co , and transition metal oxides such as Mn 2 θ 3 , Co 3 O 4 .
Alternativement, il est possible selon l'invention d'utiliser en complément un autre système catalytique convenant à l'oxydation des espèces polluantes du type hydrocarbures HC, CO ou H2.Alternatively, it is possible according to the invention to use in addition another catalytic system that is suitable for the oxidation of polluting species of HC, CO or H 2 hydrocarbon type.
Dans un exemple de structure de filtration selon l'invention, le matériau support répond à la formulation
(Zrθ2-X) i-y (M2θ3-X) y, M étant un cation de valence 3 de préférence choisi dans le groupe constitué par Y3+, Sc3+ ou les terres rares et y étant strictement supérieur à 0 et strictement inférieur à 2. De préférence, y est inférieur ou égal à 0,5, de préférence encore y est inférieur ou égal à 0,25 et de manière très préférée y est inférieur ou égal à 0,1.In an example of a filtration structure according to the invention, the support material corresponds to the formulation (Zrθ2- X) i- y (M 2 θ3- X) y, M being a cation of valency 3 preferably selected from the group consisting of Y 3+, Sc 3+, or rare earths and being strictly greater than 0 and preferably less than 2. Preferably, y is less than or equal to 0.5, more preferably y is less than or equal to 0.25, and most preferably y is less than or equal to 0.1.
Dans un autre exemple de structure de filtration selon l'invention, le matériau support répond à la formulation (ZrO2-x) i-y' (M'Oi-x)y', M' étant un cation de valence 2 de préférence choisi dans le groupe constitué par Ca2+ et Sr2+ et y' étant strictement supérieur à 0 et strictement inférieur à 2.In another example of a filtration structure according to the invention, the support material corresponds to the formulation (ZrO 2 -x) iy ' (M'Oi x ) y' , M 'being a cation of valence 2 preferably chosen from the group consisting of Ca 2+ and Sr 2+ and y 'being strictly greater than 0 and strictly less than 2.
De préférence, y' est inférieur à 0,6, de préférence encore y' est inférieur à 0,3 et de manière très préférée y' est inférieur ou égal à 0,15.Preferably, y 'is less than 0.6, more preferably y' is less than 0.3, and most preferably y 'is less than or equal to 0.15.
Dans les formules qui précèdent, la structure de filtration réduite selon l'invention est telle que x est inférieur à 0,5, de préférence inférieur à 0,1, et de manière très préférée, inférieur à 0,05. Avantageusement, x est supérieur à 0,005, de préférence supérieur à 0,01.In the preceding formulas, the reduced filtration structure according to the invention is such that x is less than 0.5, preferably less than 0.1, and very preferably less than 0.05. Advantageously, x is greater than 0.005, preferably greater than 0.01.
Ce matériau support du système catalytique à base de zircone selon l'invention présente de préférence, même après une calcination comprise 800 et 10000C, une surface spécifique d'au moins 5 m2 /g, de préférence d'au moins 10 m2/g, voire d'au moins 50 m2/g.This support material of the catalytic system based on zirconia according to the invention preferably has, even after a calcination of 800 and 1000 0 C, a specific surface area of at least 5 m 2 / g, preferably at least 10 m 2 / g, or even at least 50 m 2 / g.
La zircone faisant tout ou partie du matériau support peut être obtenue par différents dopages en substituant les atomes de Zirconium par des cations de métaux de transition de valence inférieure tels que Y3+, Sc3+, Ca2+, Sr2+ ou des terres rares. La conductivité ionique est de préférence comprise entre 1 et 10~4 S /cm dans la gamme de température de 150 à 8000C.
Au sens de la présente description, le matériau inorganique poreux présente une porosité ouverte, mesurée classiquement par porosimétrie au mercure, supérieure à 10%, de préférence supérieure à 20%, voire supérieure à 30%. Une porosité trop faible du matériau constituant les parois filtrantes conduit à une perte de charge trop élevée. Une porosité trop élevée du matériau constituant les parois filtrantes conduit à une efficacité de filtration insuffisante. Par exemple, le matériau inorganique poreux comprend ou est constitué par un matériau inorganique conducteur électronique du type carbure, par exemple le SiC, ou un siliciure, par exemple MoSi2 ou borure, par exemple TiB2, ou de la famille Lai_xSrxMnθ3 ou du type oxydes mixtes de gadolinium et cérium (CGO) . L'avantage de telles structures réalisées à base de matériau inorganique poreux conducteur électronique est de promouvoir l'activité du système catalytique par effet électrochimique, selon les principes tels que décrits par exemple dans le brevet US 6,878,354. Selon un mode possible, le matériau inorganique poreux est à base de carbure de silicium SiC, de préférence recristallisé à une température comprise entre 2100 et 24000C. En particulier, le matériau inorganique peut être à base de SiC dopé, par exemple par de l'aluminium ou de l'azote, et de telle façon que sa résistivité électronique soit inférieure de préférence à 20 Ohm. cm, de préférence encore à 15 Ohm. cm, de manière plus préférée à 10 Ohm. cm à 4000C. Par l'expression « à base de SiC », on entend au sens de la présente description que le matériau est constitué d'au moins 25% poids, de préférence d'au moins 45% poids et de manière très préférée d'au moins 70% poids de SiC.The zirconia forming all or part of the support material can be obtained by different doping by substituting the zirconium atoms with lower valence transition metal cations such as Y 3+ , Sc 3+ , Ca 2+ , Sr 2+ or rare earth. The ionic conductivity is preferably between 1 and 10 -4 S / cm in the temperature range from 150 to 800 ° C. For the purposes of the present description, the porous inorganic material has an open porosity, conventionally measured by mercury porosimetry, greater than 10%, preferably greater than 20%, or even greater than 30%. Too little porosity of the material constituting the filtering walls leads to a too high pressure drop. Too high a porosity of the material constituting the filtering walls leads to insufficient filtration efficiency. For example, the porous inorganic material comprises or consists of an electrically conductive inorganic material of the carbide type, for example SiC, or a silicide, for example MoSi 2 or boride, for example TiB 2 , or of the Lai x Sr x MnO 3 family. or mixed oxides of gadolinium and cerium (CGO). The advantage of such structures made of porous inorganic material conductive electron is to promote the activity of the catalytic system by electrochemical effect, according to the principles as described for example in US Patent 6,878,354. According to one possible mode, the porous inorganic material is based on silicon carbide SiC, preferably recrystallized at a temperature of between 2100 and 2400 ° C. In particular, the inorganic material may be based on doped SiC, for example with aluminum or nitrogen, and such that its electronic resistivity is preferably lower than 20 Ohm. cm, more preferably at 15 Ohm. cm, more preferably 10 Ohm. cm at 400 ° C. By the term "SiC-based" is meant in the sense of the present description that the material consists of at least 25% by weight, preferably at least 45% by weight and so very preferred at least 70% by weight of SiC.
Selon un autre mode possible le matériau inorganique poreux est à base de Cordiérite ou de Titanate d'Aluminium.
Selon un autre aspect, l'invention se rapporte à une poudre utilisable comme matériau support dans une structure de filtration telle que précédemment décrite, ladite poudre comprenant des particules d'oxyde de zirconium partiellement substitué par un cation M ou M' , exemptes de métal précieux du type Pt, Pd, Rh, Ag, Au et de métaux de transition, notamment Cu, Fe, Ni, Co, ledit oxyde de zirconium substitué étant à l'état réduit, sous stœchiométrique en oxygène et répondant à la formulation (Zrθ2-X) i-y (M2θ3_x) y, M étant un cation de valence 3 de préférence choisi dans le groupe constitué par Y3+, Sc3+ ou les terres rares et y étant strictement supérieur à 0 et strictement inférieur à 2 ou répondant à la formulationAccording to another possible mode, the porous inorganic material is based on Cordierite or Aluminum Titanate. According to another aspect, the invention relates to a powder that can be used as a support material in a filtration structure as previously described, said powder comprising particles of zirconium oxide partially substituted by a cation M or M ', free of metal precious metals of the Pt, Pd, Rh, Ag, Au and transition metal type, in particular Cu, Fe, Ni, Co, said substituted zirconium oxide being in the reduced state, under stoichiometric oxygen and corresponding to the formulation (ZrO 2 - X) i- y (M 2 θ3_ x) y, M being a cation of valency 3 preferably selected from the group consisting of Y 3+, Sc 3+, or rare earths and being strictly greater than 0 and strictly less at 2 or responding to the formulation
(Zrθ2-x) i-y' (M'0i-x) y' , M' étant un cation de valence 2 de préférence choisi dans le groupe constitué par Ca2+ et Sr2+ et y' étant strictement supérieur à 0 et strictement inférieur à 2, dans laquelle x est inférieur à 0,5, de préférence inférieur à 0,1, et de manière très préférée, inférieur à 0,05. Notamment, x peut être supérieur à 0,005, voire supérieur à 0,01.(ZrO 2-x) Y '(M'0i- x) y', M 'is a cation of valency 2, preferably selected from the group consisting of Ca 2+ and Sr 2+ and y' being strictly greater than 0 and strictly less than 2, wherein x is less than 0.5, preferably less than 0.1, and very preferably less than 0.05. In particular, x may be greater than 0.005, or even greater than 0.01.
Dans la poudre précédemment décrite, l'état réduit de l'oxyde de zirconium partiellement substitué peut être obtenu par un traitement thermique à une température supérieure à 4000C sous atmosphère réductrice ou par un traitement électrochimique consistant en la polarisation du matériau par application d'une tension ou d'un courant de polarisation sur celui-ci.In the powder previously described, the reduced state of the partially substituted zirconium oxide can be obtained by a heat treatment at a temperature above 400 ° C. under a reducing atmosphere or by an electrochemical treatment consisting of the polarization of the material by application of a voltage or bias current thereon.
L'utilisation d'une poudre telle que précédemment décrite est avantageuse comme matériau de support d'un catalyseur de réduction des NOx, dans une structure filtrante du type filtre à particules telle que précédemment décrite.
La poudre permet notamment l'obtention facilitée d'un système catalytique tel qu'il a été décrit précédemment, se caractérisant notamment en ce qu'il comprend au moins un métal noble ou de transition convenant pour la réduction des NOx et ledit matériau support tel que décrit précédemment, comprenant ou constitué par l'oxyde de zirconium dans un état réduit partiellement substitué par un cation trivalent M3+ ou divalent M'2+.The use of a powder as described above is advantageous as support material for an NO x reduction catalyst, in a particulate filter type filter structure as previously described. The powder makes it possible, in particular, to obtain a catalytic system such as has been previously described, characterized in particular by comprising at least one noble or transition metal suitable for the reduction of NO x and said support material. as previously described, comprising or consisting of zirconium oxide in a reduced state partially substituted by a trivalent M 3+ or divalent M ' 2+ cation.
Selon un mécanisme possible d'action, sans pour autant qu'un tel mécanisme puisse être considéré comme une quelconque théorie, le catalyseur utilisé permettrait une réaction d'oxydation sélective des NOx en NO2. Les NO2 seraient ensuite, de façon étonnante et jamais encore observée, captés au niveau du support du catalyseur sous une forme ZrO(NOs) 2. Un tel phénomène se produirait notamment lors des phases de fonctionnement du moteur en mélange pauvre en carburant.According to a possible mechanism of action, without such a mechanism being considered as any theory, the catalyst used would allow a selective oxidation reaction of NOx to NO2. The NO2 would then, surprisingly and never before, be captured at the catalyst support in a ZrO (NO 2 ) form. Such a phenomenon would occur in particular during the operating phases of the lean fuel engine.
Selon un autre aspect, le catalyseur utilisé permettrait également, lors de phases ultérieures, la réaction de réduction des NOx (NO et NO2) en N2 en particulier lors des phases de fonctionnement du moteur en mélange riche en carburant, c'est-à-dire en atmosphère réductrice. Les essais effectués par le demandeur ont en effet montré que lors de telles phases, le support à base zircone relâcherait les oxydes d' azote préalablement stockés. Sans qu'il puisse être considéré comme définitif, le mécanisme proposé pourrait être le suivant :In another aspect, the catalyst used would also allow, during subsequent phases, the NOx reduction reaction (NO and NO2) in N2, in particular during the engine operating phases in fuel-rich mixture, that is to say say in a reducing atmosphere. The tests carried out by the applicant have indeed shown that during such phases, the zirconia-based carrier would release the nitrogen oxides previously stored. Without being considered definitive, the proposed mechanism could be as follows:
ZrO(NOs)2 + O2" → ZrO2 + 2 NO2 + O2 + 2 e" Les oxydes d'azote, relâchés en masse et concentrés à proximité du catalyseur sont ensuite immédiatement réduits de manière efficace en azote gazeux N2 par ce dernier. Selon l'invention, les catalyseurs métalliques peuvent être déposés de manière conventionnelle par imprégnation à la
surface d'une poudre de zircone telle que décrite selon l'invention, par exemple selon des procédés comme ceux décrits notamment par US5884473.ZrO (NO 3 ) 2 + O 2 " → ZrO 2 + 2 NO 2 + O 2 + 2 e " The nitrogen oxides, released in bulk and concentrated in the vicinity of the catalyst, are then immediately immediately reduced to nitrogen gas N 2. by the latter. According to the invention, the metal catalysts can be deposited in a conventional manner by impregnation with the surface of a zirconia powder as described according to the invention, for example by processes such as those described in particular by US5884473.
Une telle disposition présente par rapport aux structures connues jusqu'à maintenant de nombreux avantages parmi lesquelles :Such an arrangement has compared to the previously known structures many advantages among which:
- l'introduction du système catalytique dont le matériau support fait office de piège à NOx permet avantageusement d'augmenter fortement la surface développée de catalyseur accessible aux polluants, et par suite la probabilité de contact et d'échanges entre les espèces réactives,the introduction of the catalytic system whose support material acts as a NOx trap advantageously makes it possible to greatly increase the catalyst surface area accessible to the pollutants, and consequently the probability of contact and exchanges between the reactive species,
- le matériau support constitué selon l'invention présente en outre une grande stabilité thermique par rapport aux matériaux support de type alumine, du fait notamment d'une meilleure résistance au frittage des particules de catalyseurs métalliques déposées au contact des lacunes d'oxygène du matériau support, - le matériau support constitué selon l'invention présente une grande réactivation en milieu riche en carburant par rapport aux solutions antérieures.the support material constituted according to the invention also has a high thermal stability with respect to alumina-type support materials, in particular because of a better sintering resistance of the metal catalyst particles deposited in contact with the oxygen vacancies of the material support, - the support material formed according to the invention has a high reactivation in a fuel-rich medium compared to previous solutions.
- un nombre limité des constituants du système doit être déposé sur le support, ce qui diminue fortement la dépendance des performances du système par rapport aux conditions de dépôt du catalyseur sur le support,a limited number of the constituents of the system must be deposited on the support, which strongly reduces the dependence of the performances of the system with respect to the conditions of deposition of the catalyst on the support,
- une augmentation de l'efficacité catalytique, une meilleure dispersion des catalyseurs métalliques sur le matériau support pouvant être obtenue du fait de l'absence de substance additionnelle utile au stockage des NOx,an increase in the catalytic efficiency, a better dispersion of the metal catalysts on the support material that can be obtained due to the absence of additional substance useful for the storage of NO x ,
- le système catalytique selon l'invention ne comprenant pas de Baryum est donc beaucoup moins sensible à la
présence d'oxydes de soufre (SOx) dans les gaz à traiter .the catalytic system according to the invention not comprising barium is therefore much less sensitive to the presence of sulfur oxides (SO x ) in the gases to be treated.
La présente invention trouve tout particulièrement son application dans les structures à parois filtrantes utilisées pour la purification et les plus efficaces pour la filtration d'un gaz d'échappement d'un moteur diesel. De telles structures, généralement désignées sous le terme filtres à particules, comprennent au moins un et de préférence une pluralité de blocs monolithiques en nid d'abeille reliés par un ciment de joint. A la différence des dispositifs de purification précédemment décrits, dans de tels filtres, le ou lesdits blocs comprenant un ensemble de conduits ou canaux adjacents d'axes parallèles entre eux séparés par des parois poreuses, obturés par des bouchons à l'une ou l'autre de leurs extrémités pour délimiter des conduits d'entrée s ' ouvrant suivant une face d'admission des gaz et des conduits de sortie s ' ouvrant suivant une face d'évacuation des gaz, de telle façon que le gaz traverse les parois poreuses. Des exemples de telles structures assemblées ou non assemblées sont par exemple décrits dans les publications EP 0816065, EP 1142619, EP1306358 ou encore EP 1591430.The present invention is particularly applicable in the filter wall structures used for purification and the most effective for filtering an exhaust gas from a diesel engine. Such structures, generally referred to as particle filters, comprise at least one and preferably a plurality of monolithic honeycomb blocks joined by a joint cement. Unlike the purification devices described above, in such filters, the block or blocks comprising a set of adjacent ducts or channels of axes parallel to each other separated by porous walls, closed by plugs to one or the other. other of their ends to define inlet ducts opening on a gas inlet face and outlet ducts opening on a gas evacuation face, so that the gas passes through the porous walls. Examples of such assembled or unassembled structures are for example described in EP 0816065, EP 1142619, EP1306358 or EP 1591430.
Selon un premier mode de réalisation possible, la structure inorganique poreuse est imprégnée avec une solution aqueuse comportant des particules de zircone présentant les caractéristiques selon l'invention, c'est-à- dire que le support est un oxyde de zirconium réduit répondant aux formulations (Zrθ2-X) i-y (M2θ3_x) y ou (ZrO2-x) i-y' (M'Oi-x)y', M étant un cation de valence 3 et M' étant un cation de valence 2.According to a first possible embodiment, the porous inorganic structure is impregnated with an aqueous solution comprising zirconia particles having the characteristics according to the invention, that is to say that the support is a reduced zirconium oxide corresponding to the formulations (Zrθ2- X) iy (M 2 θ3_ x) y or (ZrO 2 - x) y '(me IM-x) y', wherein M is a cation of valence 3 and M 'is a cation of valency 2 .
Selon une caractéristique essentielle de l'invention, ledit support du type zircone substituée est sous une forme
réduite, c'est-à-dire qu'il a subi un traitement de réduction l'ayant amené dans un état déficitaire (ou sous stoechiométrique) en oxygène, ledit traitement de réduction pouvant être choisi selon l'invention parmi tous les traitements connus à cet effet et notamment par un chauffage sous atmosphère réductrice, par électrochimie, etc .According to an essential characteristic of the invention, said substituted zirconia type support is in a form reduced, that is to say that it has undergone a reduction treatment having brought it in a deficit state (or stoichiometric) oxygen, said reduction treatment can be chosen according to the invention among all known treatments for this purpose and in particular by heating in a reducing atmosphere, by electrochemistry, etc.
Selon l'invention, l'état réduit du support peut être obtenue notamment par un traitement de réduction par voie thermique c'est-à-dire par un traitement à haute température, par exemple entre 400 et 10000C, sous atmosphère réductrice. Ledit traitement peut typiquement être effectué sous une pression suffisante d'au moins 0,1 atm (1 atm = 105 Pa) et de préférence 1 atm de H2, éventuellement en mélange avec un autre gaz neutre. Le traitement de réduction peut également être mené sous une atmosphère réductrice d'hydrocarbure léger tel que par exemple le méthane, le propane, le propène ou le monoxyde de carbone CO, dans une gamme de température comprise entre 400 et 10000C. La durée du traitement thermique peut être adaptée à la granulométrie de départ et/ou la surface spécifique de la poudre visée pour le dépôt sur la structure et/ou la température. Cette durée est en général au moins égale à 10 minutes et de préférence supérieure ou égale à 60 minutes.According to the invention, the reduced state of the support can be obtained in particular by a reduction treatment by thermal means that is to say by a high temperature treatment, for example between 400 and 1000 0 C, under a reducing atmosphere. Said treatment may typically be carried out under a sufficient pressure of at least 0.1 atm (1 atm = 10 5 Pa) and preferably 1 atm of H 2 , optionally mixed with another neutral gas. The reduction treatment can also be carried out under a reducing atmosphere of light hydrocarbon such as for example methane, propane, propene or carbon monoxide CO, in a temperature range between 400 and 1000 ° C. The duration heat treatment can be adapted to the starting granulometry and / or the specific surface of the powder intended for the deposition on the structure and / or the temperature. This duration is in general at least equal to 10 minutes and preferably greater than or equal to 60 minutes.
Selon ce premier mode de réalisation de l'invention, le traitement de réduction est effectué dans une étape préalable à l'imprégnation de la structure par les particules de Zircone substituée. La structure comportant le support à l'état réduit est ensuite imprégnée en une seule ou plusieurs étapes par le ou les systèmes catalytiques nécessaires à la conversion des NOx en N2.
Selon un deuxième mode de réalisation possible, la structure inorganique poreuse est cette fois d'abord imprégnée avec une solution aqueuse comportant des particules de zircone obtenue par dopage en substituant les atomes de Zirconium par des cations de métaux de transition de valence inférieure (3 ou 2) tels que Y3+, Sc3+, Ca2+, Sr2+ ou des terres rares pour obtenir au final un matériau de la formulation précédemment décrite.According to this first embodiment of the invention, the reduction treatment is carried out in a step prior to the impregnation of the structure with the substituted zirconia particles. The structure comprising the support in the reduced state is then impregnated in one or more steps by the catalytic system (s) necessary for the conversion of NO x to N 2 . According to a second possible embodiment, the porous inorganic structure is this time first impregnated with an aqueous solution comprising doped zirconia particles by substituting the zirconium atoms with lower valence transition metal cations (3 or 4). 2) such as Y 3+ , Sc 3+ , Ca 2+ , Sr 2+ or rare earths to ultimately obtain a material of the previously described formulation.
Selon ce deuxième mode, le traitement de réduction par voie thermique est réalisé cette fois sur la structure imprégnée par le matériau support, c'est à dire après le dépôt de la zircone. Typiquement, le traitement de réduction peut être réalisé dans les mêmes conditions que celles déjà décrites dans le mode précédent. Après le traitement thermique, la structure est imprégnée en une seule ou plusieurs étapes par le ou les systèmes catalytiques nécessaires à la conversion des NOx en N2. Ce deuxième de réalisation présente pour avantage de permettre l'imprégnation de la structure poreuse dans des conditions non nécessairement réductrices, par exemple sous air .According to this second embodiment, the heat reduction treatment is performed this time on the structure impregnated with the support material, ie after the deposition of the zirconia. Typically, the reduction treatment can be carried out under the same conditions as those already described in the previous mode. After the heat treatment, the structure is impregnated in one or more steps by the catalytic system (s) necessary for the conversion of NO x to N 2 . This second embodiment has the advantage of permitting the impregnation of the porous structure under conditions that are not necessarily reducing, for example under air.
Selon un troisième mode de réalisation possible, la structure inorganique poreuse est imprégnée avec une solution aqueuse comportant des particules de zircone obtenue par dopage en substituant les atomes de Zirconium par des cations de métaux de transition de valence inférieure (3 ou 2) tels que Y3+, Sc3+, Ca2+, Sr2+ ou des terres rares pour obtenir au final un matériau de la formulation précédemment décrite. Après un traitement de calcination, qui peut être facultatif, la structure est imprégnée en une seule ou plusieurs étapes par les le ou les systèmes catalytiques à la conversion des NOx en N2.According to a third possible embodiment, the porous inorganic structure is impregnated with an aqueous solution comprising doped zirconia particles by substituting the zirconium atoms with lower valence (3 or 2) transition metal cations such as Y 3+ , Sc 3+ , Ca 2+ , Sr 2+ or rare earths to ultimately obtain a material of the previously described formulation. After a calcination treatment, which may be optional, the structure is impregnated in one or more steps by the catalytic system or systems to the conversion of NO x to N 2 .
Selon une variante possible, les catalyseurs et la zircone sont déposés en même temps sur la structure.
Selon ce troisième mode, le traitement de réduction par voie thermique, qui peut être du même type que celui précédemment décrit, est réalisé sur la structure déjà imprégnée par le catalyseur et son matériau support. Ce troisième mode de réalisation permet d'effectuer le traitement thermique à plus basse température typiquement à une température entre 400 et 600 0C, en raison de l'activité réductrice des métaux catalytiques .According to one possible variant, the catalysts and the zirconia are deposited at the same time on the structure. According to this third mode, the thermal reduction treatment, which may be of the same type as that previously described, is carried out on the structure already impregnated by the catalyst and its support material. This third embodiment makes it possible to carry out the heat treatment at a lower temperature, typically at a temperature between 400 and 600 ° C., because of the reducing activity of the catalytic metals.
Il est bien entendu que toute méthode ou procédé connu de réduction de l'oxyde de zirconium partiellement substitué peut être utilisé au sens de l'invention. Par exemple, l'état réduit de l'oxyde de zirconium partiellement substitué peut également être obtenu selon l'invention par un traitement électrochimique consistant en la polarisation du matériau par application d'une tension ou d'un courant de polarisation sur celui-ci.It is understood that any known method or method for reducing partially substituted zirconium oxide may be used within the meaning of the invention. For example, the reduced state of the partially substituted zirconium oxide can also be obtained according to the invention by an electrochemical treatment consisting of the polarization of the material by applying a voltage or a polarization current thereon. .
L' invention et ses avantages seront mieux compris à la lecture des modes de réalisation non limitatifs et de l'exemple qui suivent :The invention and its advantages will be better understood on reading the following nonlimiting embodiments and example:
EXEMPLE 1 (Comparatif) :EXAMPLE 1 (Comparative)
Selon ce premier exemple, on a synthétisé des monolithes en nid d'abeille de forme cylindrique en Carbure de Silicium (SiC) recristallisé selon les techniques conventionnelles déjà bien connues dans le domaine et par exemple décrits dans la demande de brevet EP 1 142 619 Al. Dans un premier temps on a d'abord réalisé dans un malaxeur un mélange de particules de carbure de silicium de pureté supérieure à 98% conformément au mode de fabrication d'une structure en R-SiC décrit dans la demande WO 1994/22556. Le mélange est obtenu à partir d'une fraction grossière de particules de SiC (75% poids) dont le diamètre médian des particules est supérieur à 10 micromètres et d'une fraction
granulométrique fine (25% poids) dont la taille médiane des particules est inférieure à 1 microns. Au sens de la présente description, le diamètre médian désigne le diamètre des particules au dessous duquel se trouve 50% en masse de la population. A la portion de particules de SiC sont ajoutés, par rapport à leur masse totale, 7% poids d'un porogène du type polyéthylène et 5% poids d'un liant organique du type dérivé de cellulose.According to this first example, cylindrical honeycomb monoliths of recrystallized silicon carbide (SiC) cylindrical shape have been synthesized according to the conventional techniques already well known in the art and for example described in patent application EP 1 142 619 A1. In a first step, a mixture of silicon carbide particles with a purity greater than 98% was first produced in a kneader in accordance with the method of manufacturing an R-SiC structure described in application WO 1994/22556. The mixture is obtained from a coarse fraction of SiC particles (75% by weight) whose median particle diameter is greater than 10 microns and a fraction of fine granulometry (25% weight) with a median particle size of less than 1 micron. For the purpose of this description, the median diameter refers to the diameter of the particles below which 50% by mass of the population is found. To the portion of SiC particles are added, based on their total weight, 7% by weight of a porogen of the polyethylene type and 5% by weight of an organic binder of the cellulose derivative type.
On ajoute également de l'eau à hauteur de 20% poids de la somme des constituants précédents et on malaxe jusqu'à obtenir une pâte homogène et dont la plasticité permet la formation de monolithes ou l'extrusion à travers une filière d'une structure en nid d'abeille.Water is also added up to 20% by weight of the sum of the preceding constituents and kneaded to obtain a homogeneous paste whose plasticity allows the formation of monoliths or the extrusion through a die of a structure honeycomb.
Après extrusion, les monolithes en nid d'abeille en SiC recristallisé sont séchés déliantes, bouchés et cuits sous atmosphère neutre à une température de 22000C. Dans le détail, les conditions expérimentales optimales sont les suivantes : montée en température de 20°C/heure jusqu'à 22000C puis palier en température de 6 heures à 22000C.After extrusion, the recrystallized SiC honeycomb monoliths are dried deliantes, corked and fired under a neutral atmosphere at a temperature of 2200 ° C. In detail, the optimal experimental conditions are as follows: rise in temperature of 20 ° C. / hour up to 2200 0 C then temperature plateau of 6 hours at 2200 0 C.
Ces monolithes présentent une structure en nid d'abeille dont les caractéristiques sont données dans le tableau 1 suivant :These monoliths have a honeycomb structure whose characteristics are given in Table 1 below:
Tableau 1 Table 1
Dans un second temps, on réalise une suspension aqueuse chargée à 3% en masse de poudre de zircone dopée à 8% molaire d'oxyde d' Yttrium (zirconia powder basic grade TZ8Y de surface spécifique de 12 m2 /g et de densité 5,9) commercialisée par la société Tosoh. Les monolithes sont plongés selon un mode de mise en œuvre similaire à celui décrit dans le brevet US 5,866,210 dans cette solution de manière à imprégner environ 1,5% en masse de zircone dopée par rapport au monolithe. Un séchage est effectué à 400C puis une calcination à 5000C sous air est réalisée selon une vitesse de chauffe de 100°C/h et un palier à la température maximale d'une heure . Dans un troisième temps, on imprègne le monolithe avec une solution aqueuse de chlorure de dinitrodiamine de platine. Le monolithe est séché à 400C, puis calciné à 5000C sous air, selon une vitesse de chauffe de 100°C/h et un palier à la température maximale d'une heure. Dans un quatrième temps, on imprègne le monolithe avec une solution aqueuse de nitrate de Rhodium, le monolithe est ensuite séché à 400C puis calciné jusqu'à 5000C sous air, selon une vitesse de chauffe de 100°C/h, avec un palier à la température maximale d'une heure. La concentration des solutions de métaux précieux et le processus de dépôt sont adaptés pour constituer des monolithes catalysés dont l'analyse chimique montre les caractéristiques suivantes :In a second step, an aqueous suspension loaded with 3% by weight of zirconia powder doped with 8 mol% of yttrium oxide (zirconia powder basic grade TZ8Y with a specific surface area of 12 m 2 / g and a density of 9) marketed by Tosoh. The monoliths are immersed in an embodiment similar to that described in US Pat. No. 5,866,210 in this solution so as to impregnate about 1.5% by weight of zirconia doped with respect to the monolith. Drying is carried out at 40 ° C. and then calcination at 500 ° C. under air is carried out at a heating rate of 100 ° C./h and a plateau at the maximum temperature of one hour. In a third step, the monolith is impregnated with an aqueous solution of platinum dinitrodiamine chloride. The monolith is dried at 40 ° C. and then calcined at 500 ° C. in air, according to a heating rate of 100 ° C./hour and a plateau at the maximum temperature of one hour. In a fourth step, the monolith is impregnated with an aqueous solution of Rhodium nitrate, the monolith is then dried at 40 ° C. and then calcined to 500 ° C. under air, with a heating rate of 100 ° C./h, with a bearing at the maximum temperature of one hour. The concentration of precious metal solutions and the deposition process are adapted to constitute catalysed monoliths whose chemical analysis shows the following characteristics:
EXEMPLE 2 (Selon l' invention) EXAMPLE 2 (According to the invention)
Le protocole expérimental déjà décrit dans l'exemple 1 a été entièrement repris dans cet exemple, excepté que cette deuxième série de monolithes a subi après imprégnation du catalyseur supporté un traitement additionnel de réduction sous H2 pur à 6000C pendant 1 heure .The experimental protocol already described in Example 1 was entirely taken up in this example, except that this second series of monoliths underwent after impregnation of the supported catalyst additional reduction treatment in pure H 2 at 600 0 C for 1 hour.
Il a été vérifié que la concentration en métaux nobles n'est pas modifiée par cette étape supplémentaire.It has been verified that the concentration of noble metals is not changed by this additional step.
Les analyses effectuées ont montrées que la zircone substituée et réduite répondait sensiblement à la formulation (Zrθ2-X) i-y (M2θ3_x) y, dans laquelle y est d'environ 0,08 et x est proche de 0,02.The analyzes have shown that the zirconia substituted and reduced substantially corresponded to the formulation (Zrθ2- X) i- y (M 2 θ3_ x) y, wherein y is about 0.08 and x is close to 0.02 .
Les performances des monolithes selon les exemples 1 et 2 ont été mesurées à une température de 250 et 3000C grâce aux deux mélanges synthétiques de gaz selon le tableau 2, caractéristiques des gaz d'échappement dans un fonctionnement d'un moteur Diesel en mélange pauvreThe performances of the monoliths according to Examples 1 and 2 were measured at a temperature of 250 and 300 ° C. thanks to the two synthetic gas mixtures according to Table 2, characteristics of the exhaust gases in an operation of a mixed diesel engine. poor
(mélange 1) et dans un fonctionnement d'un moteur Diesel en mélange riche (mélange 2) .(mixture 1) and in operation of a diesel engine rich mixture (mixture 2).
Tableau 2Table 2
Le test est opéré de la manière suivante : Le mélange de gaz pauvre 1 passe d'abord sur le monolithe catalysé
maintenu dans un four électrique à 250 ou 3000C. La composition des gaz traversant le monolithe est alternée selon le protocole suivant : d' abord le mélange 1 pendant 3 minutes puis basculement vers le mélange de gaz 2 (riche) pendant 2 minutes, puis vers le mélange 1 (3 minutes) et ainsi de suite. La composition des gaz en sortie de four est analysée après stabilisation du système de façon à connaître la quantité de NOx convertie en N2. Le test tel qu'il vient d'être décrit a été mené dans les mêmes conditions pour chaque température 250 et 3000C sur le monolithe selon l'exemple 1 (zircone non réduite) et sur le monolithe selon l'exemple 2 (zircone réduite) . Le débit de gaz est de 10 1/h pour les deux mélanges. Des capteurs de mesure du type thermocouple de température sont placés à 5mm environ de la surface de sortie du monolithe. L'analyse des gaz est effectuée à la sortie du réacteur par des analyseurs IR et μGC .The test is carried out as follows: The mixture of lean gas 1 passes first on the catalysed monolith maintained in an electric oven at 250 or 300 ° C. The composition of the gases passing through the monolith is alternated according to the following protocol: first mixture 1 for 3 minutes and then rocking to the gas mixture 2 (rich) for 2 minutes, then to mixture 1 (3 minutes) and so on. The composition of the gases at the furnace outlet is analyzed after stabilization of the system so as to know the amount of NO x converted into N 2 . The test as just described was carried out under the same conditions for each temperature 250 and 300 ° C. on the monolith according to Example 1 (unreduced zirconia) and on the monolith according to Example 2 (zirconia). scaled down) . The gas flow rate is 10 1 / h for both mixtures. Thermocouple type temperature sensors are placed about 5mm from the exit surface of the monolith. The gas analysis is performed at the outlet of the reactor by IR and μGC analyzers.
Les résultats reportés dans le tableau 3 montrent que le monolithe selon l'invention (exemple 2) présente un taux de conversion des NOx nettement supérieur à celui du filtre comparatif (exemple 1) .The results reported in Table 3 show that the monolith according to the invention (Example 2) has a conversion rate of NOx significantly higher than that of the comparative filter (Example 1).
Tableau 3
Table 3
Claims
1. Structure de filtration d'un gaz issu d'un moteur diesel, chargé en polluants gazeux du type oxydes d'azote NOx et en particules solides, du type filtre à particules, ladite structure comprenant un ensemble de canaux adjacents longitudinaux d'axes parallèles entre eux séparés par des parois poreuses filtrantes constituées par ledit matériau inorganique poreux, lesdits canaux étant alternativement bouchés à l'une ou l'autre des extrémités de la structure de façon à définir des canaux d'entrée et des canaux de sortie pour le gaz à filtrer, et de façon à forcer ledit gaz à traverser les parois poreuses séparant les canaux d'entrée et de sortie, ladite structure de filtration se caractérisant en ce qu'elle comprend un système catalytique comprenant au moins un métal noble ou de transition convenant pour la réduction des NOx et un matériau support, dans lequel ledit matériau support comprend ou est constitué par un oxyde de zirconium partiellement substitué par un cation trivalent M3+ ou par un cation divalent M'2+, ledit oxyde de zirconium étant dans un état réduit, sous stœchiométrique en oxygène .1. Filtration structure of a gas from a diesel engine, charged with gaseous pollutants of the NO x type nitrogen oxide type and solid particles, of the particulate filter type, said structure comprising a set of longitudinal adjacent channels of parallel axes separated by porous filtering walls constituted by said porous inorganic material, said channels being alternately plugged at one or the other end of the structure so as to define input channels and output channels for the gas to be filtered, and so as to force said gas to pass through the porous walls separating the inlet and outlet channels, said filtration structure being characterized in that it comprises a catalytic system comprising at least one noble metal or transition suitable for reducing NO x and a carrier material, wherein said carrier material comprises or consists of a partially substituted zirconium oxide by M 3+ a trivalent cation or a divalent cation M '2+, said zirconium oxide being in a reduced state, substoichiometric oxygen.
2. Structure de filtration selon la revendication 1, dans laquelle le système catalytique est choisi pour convenir également à l'oxydation des espèces polluantes du type hydrocarbures HC, CO ou H2.2. Filtration structure according to claim 1, wherein the catalytic system is chosen to also be suitable for the oxidation of polluting species of HC, CO or H 2 hydrocarbon type.
3. Structure de filtration selon l'une des revendications précédentes, dans laquelle le matériau support répond à la formulation (Zrθ2-X) i-y (M2θ3_x) y M étant un cation de valence 3 de préférence choisi dans le groupe constitué par Y3+, Sc3+ ou les terres rares et y étant strictement supérieur à 0 et strictement inférieur à 2.3. filtering structure according to any of the preceding claims, wherein the carrier material corresponds to the formulation (Zrθ2- X) i- y (M 2 θ3_ x) y wherein M is a cation of valency 3 preferably selected from the group consisting by Y 3+ , Sc 3+ or rare earths and being strictly greater than 0 and strictly less than 2.
4. Structure de filtration selon la revendication précédente, dans laquelle y est inférieur ou égal à4. Filtration structure according to the preceding claim, wherein y is less than or equal to
0,5, de préférence dans laquelle y est inférieur ou égal à 0,25 et de manière très préférée dans laquelle y est inférieur ou égal à 0,1.0.5, preferably wherein y is less than or equal to 0.25 and most preferably wherein y is less than or equal to 0.1.
5. Structure de filtration selon l'une des revendications 1 ou 2, dans laquelle le matériau support répond à la formulation (Zrθ2-X) i-y' (M'Oi-x) y- , M' étant un cation de valence 2 de préférence choisi dans le groupe constitué par Ca2+ et Sr2+ et y' étant strictement supérieur à 0 et strictement inférieur à 2.5. filtration structure according to one of claims 1 or 2, wherein the carrier material corresponds to the formulation (Zrθ2- X) i- y '(Me IM-x) y -, wherein M' is a cation of valency 2 preferably selected from the group consisting of Ca 2+ and Sr 2+ and y 'being strictly greater than 0 and strictly less than 2.
6. Structure de filtration selon la revendication précédente, dans laquelle y' est inférieur à 0,6, de préférence dans laquelle y' est inférieur à 0,3, de manière très préférée dans laquelle y' est inférieur ou égal à 0,15.6. Filtration structure according to the preceding claim, wherein y 'is less than 0.6, preferably wherein y' is less than 0.3, very preferably wherein y 'is less than or equal to 0.15 .
7. Structure de filtration selon l'une des revendications 3 à 6, dans laquelle x est inférieur à 0,5, de préférence inférieur à 0,1, et de manière très préférée, inférieur à 0,05.7. Filtration structure according to one of claims 3 to 6, wherein x is less than 0.5, preferably less than 0.1, and very preferably less than 0.05.
8. Structure de filtration selon la revendication 7 dans laquelle x est supérieur à 0,005, de préférence supérieur à 0,01.The filtration structure of claim 7 wherein x is greater than 0.005, preferably greater than 0.01.
9. Structure de filtration selon l'une des revendications précédentes, dans laquelle ledit matériau support présente une surface spécifique d'au moins 5 m2 /g. 9. Filtration structure according to one of the preceding claims, wherein said support material has a specific surface area of at least 5 m 2 / g.
10. Structure de filtration selon l'une des revendications précédentes, dans laquelle le système catalytique comprend au moins un métal précieux choisi parmi Pt et/ou Pd et/ou Rh et/ou Ag et/ou Au et/ou les métaux de transition, notamment Cu, Fe, Ni, Co, et les oxydes de métaux de transition comme Mn2θ3, C03O4.10. Filtration structure according to one of the preceding claims, wherein the catalytic system comprises at least one precious metal selected from Pt and / or Pd and / or Rh and / or Ag and / or Au and / or transition metals , especially Cu, Fe, Ni, Co, and transition metal oxides such as Mn 2 θ 3, CO 3 O 4.
11. Structure de filtration selon l'une des revendications précédentes, dans laquelle ladite structure est en carbure de silicium SiC, en cordiérite ou en titanate d' aluminium.11. Filtration structure according to one of the preceding claims, wherein said structure is silicon carbide SiC, cordierite or aluminum titanate.
12. Poudre utilisable comme matériau support dans une structure de filtration selon l'une des revendications précédentes, ladite poudre comprenant des particules d'oxyde de zirconium partiellement substitué par un cation M ou M' , exemptes de métal précieux du type Pt, Pd, Rh, Ag, Au et de métaux de transition, notamment Cu, Fe, Ni, Co, ledit oxyde de zirconium substitué étant à l'état réduit, sous stœchiométrique en oxygène et répondant à la formulation (Zrθ2-X) i-y (M2θ3_x) y, M étant un cation de valence 3 de préférence choisi dans le groupe constitué par Y3+, Sc3+ ou les terres rares et y étant strictement supérieur à 0 et strictement inférieur à 2 ou répondant à la formulation (Zrθ2-X)i- y' (M' Oi-X) y' , M' étant un cation de valence 2 de préférence choisi dans le groupe constitué par Ca2+ et Sr2+, y' étant strictement supérieur à 0 et strictement inférieur à 2 et x étant inférieur à 0,5, de préférence inférieur à 0,1, et de manière très préférée, inférieur à 0, 05. 12. Powder used as a support material in a filtration structure according to one of the preceding claims, said powder comprising zirconium oxide particles partially substituted by an M or M 'cation, free of precious metal of the Pt, Pd type, Rh, Ag, Au, and transition metals including Cu, Fe, Ni, Co, said substituted zirconium oxide being in a reduced state, substoichiometric in oxygen and having the formulation (Zrθ2- X) i- y ( M 2 θ 3- x ) y , M being a cation of valence 3 preferably selected from the group consisting of Y 3+ , Sc 3+ or rare earths and being strictly greater than 0 and strictly less than 2 or corresponding to the formulation (Zrθ2- X) i- y '(M' IM-X) y ', wherein M' is a cation of valency 2, preferably selected from the group consisting of Ca 2+ and Sr 2+, y 'being strictly greater than 0 and strictly less than 2 and x being less than 0.5, preferably less than 0.1, and most preferably less than 0.05.
13. Poudre selon la revendication 12, dans laquelle x est supérieur à 0,005, de préférence supérieur à 0,01.13. The powder of claim 12, wherein x is greater than 0.005, preferably greater than 0.01.
14. Procédé d'obtention d'une poudre selon l'une des revendications 12 ou 13, dans lequel l'état réduit de l'oxyde de zirconium partiellement substitué est obtenu par un traitement thermique à une température supérieure à 4000C sous atmosphère réductrice.14. A process for obtaining a powder according to one of claims 12 or 13, wherein the reduced state of partially substituted zirconium oxide is obtained by a heat treatment at a temperature above 400 0 C under atmosphere reductive.
15. Procédé d'obtention d'une poudre selon l'une des revendications 12 ou 13, dans lequel l'état réduit de l'oxyde de zirconium partiellement substitué est obtenu par un traitement électrochimique consistant en la polarisation du matériau par application d'une tension ou d'un courant de polarisation sur celui-ci. 15. Process for obtaining a powder according to one of claims 12 or 13, wherein the reduced state of the partially substituted zirconium oxide is obtained by an electrochemical treatment consisting of the polarization of the material by application of a voltage or bias current thereon.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR0858720A FR2939695B1 (en) | 2008-12-17 | 2008-12-17 | PURIFICATION STRUCTURE INCORPORATING A CATALYSIS SYSTEM SUPPORTED BY A REDUCED ZIRCONY. |
| PCT/FR2009/052576 WO2010076509A1 (en) | 2008-12-17 | 2009-12-16 | Purification structure including a catalysis system supported by a zircon in reduced state |
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| Publication Number | Publication Date |
|---|---|
| EP2379207A1 true EP2379207A1 (en) | 2011-10-26 |
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| EP09803879A Withdrawn EP2379207A1 (en) | 2008-12-17 | 2009-12-16 | Purification structure including a catalysis system supported by a zircon in reduced state |
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| US (1) | US8802044B2 (en) |
| EP (1) | EP2379207A1 (en) |
| JP (1) | JP5587907B2 (en) |
| KR (1) | KR20110096044A (en) |
| CN (1) | CN102256688B (en) |
| EA (1) | EA201170830A1 (en) |
| FR (1) | FR2939695B1 (en) |
| WO (1) | WO2010076509A1 (en) |
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| US9895674B1 (en) * | 2015-09-14 | 2018-02-20 | The United States Of America As Represented By The Secretary Of The Army | Multi-functional media for the removal of basic and acidic gases and other toxic vapors |
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2008
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- 2009-12-16 KR KR1020117013808A patent/KR20110096044A/en not_active Application Discontinuation
- 2009-12-16 CN CN200980150676.6A patent/CN102256688B/en not_active Expired - Fee Related
- 2009-12-16 US US13/139,736 patent/US8802044B2/en not_active Expired - Fee Related
Non-Patent Citations (1)
| Title |
|---|
| See references of WO2010076509A1 * |
Also Published As
| Publication number | Publication date |
|---|---|
| US8802044B2 (en) | 2014-08-12 |
| EA201170830A1 (en) | 2011-12-30 |
| KR20110096044A (en) | 2011-08-26 |
| FR2939695A1 (en) | 2010-06-18 |
| WO2010076509A1 (en) | 2010-07-08 |
| JP2012512020A (en) | 2012-05-31 |
| FR2939695B1 (en) | 2011-12-30 |
| CN102256688A (en) | 2011-11-23 |
| CN102256688B (en) | 2015-01-28 |
| US20110250112A1 (en) | 2011-10-13 |
| JP5587907B2 (en) | 2014-09-10 |
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