JP5305133B2 - Nitrogen oxide purification catalyst and method for producing the same - Google Patents
Nitrogen oxide purification catalyst and method for producing the same Download PDFInfo
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- MWUXSHHQAYIFBG-UHFFFAOYSA-N Nitric oxide Chemical compound O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 title claims description 183
- 239000003054 catalyst Substances 0.000 title claims description 157
- 238000000746 purification Methods 0.000 title claims description 134
- 238000004519 manufacturing process Methods 0.000 title claims description 16
- 229910052751 metal Inorganic materials 0.000 claims description 143
- 239000002184 metal Substances 0.000 claims description 142
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 57
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 claims description 55
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 claims description 55
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 40
- 229910052742 iron Inorganic materials 0.000 claims description 30
- 229910052721 tungsten Inorganic materials 0.000 claims description 29
- 229910021529 ammonia Inorganic materials 0.000 claims description 20
- 239000010949 copper Substances 0.000 claims description 19
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 claims description 19
- 229910052750 molybdenum Inorganic materials 0.000 claims description 18
- ZOKXTWBITQBERF-UHFFFAOYSA-N Molybdenum Chemical compound [Mo] ZOKXTWBITQBERF-UHFFFAOYSA-N 0.000 claims description 17
- 239000011733 molybdenum Substances 0.000 claims description 17
- 239000010937 tungsten Substances 0.000 claims description 17
- 229910052802 copper Inorganic materials 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 16
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 claims description 14
- 239000011572 manganese Substances 0.000 claims description 14
- 229910052748 manganese Inorganic materials 0.000 claims description 13
- 238000002485 combustion reaction Methods 0.000 claims description 11
- 150000001875 compounds Chemical class 0.000 claims description 11
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims description 10
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 6
- 229910052710 silicon Inorganic materials 0.000 claims description 6
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 5
- 239000010703 silicon Substances 0.000 claims description 5
- WPBNNNQJVZRUHP-UHFFFAOYSA-L manganese(2+);methyl n-[[2-(methoxycarbonylcarbamothioylamino)phenyl]carbamothioyl]carbamate;n-[2-(sulfidocarbothioylamino)ethyl]carbamodithioate Chemical compound [Mn+2].[S-]C(=S)NCCNC([S-])=S.COC(=O)NC(=S)NC1=CC=CC=C1NC(=S)NC(=O)OC WPBNNNQJVZRUHP-UHFFFAOYSA-L 0.000 claims description 4
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- 239000000843 powder Substances 0.000 description 28
- 239000007789 gas Substances 0.000 description 27
- 230000000694 effects Effects 0.000 description 25
- 230000000052 comparative effect Effects 0.000 description 24
- -1 halogen salts Chemical class 0.000 description 16
- 150000003839 salts Chemical group 0.000 description 16
- 238000011156 evaluation Methods 0.000 description 8
- 229910044991 metal oxide Inorganic materials 0.000 description 7
- 150000004706 metal oxides Chemical class 0.000 description 7
- 229910021536 Zeolite Inorganic materials 0.000 description 6
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 6
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 description 6
- 238000010304 firing Methods 0.000 description 6
- MVFCKEFYUDZOCX-UHFFFAOYSA-N iron(2+);dinitrate Chemical compound [Fe+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O MVFCKEFYUDZOCX-UHFFFAOYSA-N 0.000 description 6
- 239000010457 zeolite Substances 0.000 description 6
- 229910016870 Fe(NO3)3-9H2O Inorganic materials 0.000 description 4
- WCUXLLCKKVVCTQ-UHFFFAOYSA-M Potassium chloride Chemical compound [Cl-].[K+] WCUXLLCKKVVCTQ-UHFFFAOYSA-M 0.000 description 4
- 239000002253 acid Substances 0.000 description 4
- 239000002244 precipitate Substances 0.000 description 4
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 4
- WEVYAHXRMPXWCK-UHFFFAOYSA-N Acetonitrile Chemical compound CC#N WEVYAHXRMPXWCK-UHFFFAOYSA-N 0.000 description 3
- 229910021591 Copper(I) chloride Inorganic materials 0.000 description 3
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 3
- 239000007864 aqueous solution Substances 0.000 description 3
- OXBLHERUFWYNTN-UHFFFAOYSA-M copper(I) chloride Chemical compound [Cu]Cl OXBLHERUFWYNTN-UHFFFAOYSA-M 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- CGFYHILWFSGVJS-UHFFFAOYSA-N silicic acid;trioxotungsten Chemical compound O[Si](O)(O)O.O=[W]1(=O)O[W](=O)(=O)O[W](=O)(=O)O1.O=[W]1(=O)O[W](=O)(=O)O[W](=O)(=O)O1.O=[W]1(=O)O[W](=O)(=O)O[W](=O)(=O)O1.O=[W]1(=O)O[W](=O)(=O)O[W](=O)(=O)O1 CGFYHILWFSGVJS-UHFFFAOYSA-N 0.000 description 3
- 229910018072 Al 2 O 3 Inorganic materials 0.000 description 2
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- 241001168730 Simo Species 0.000 description 2
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 description 2
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 239000004202 carbamide Substances 0.000 description 2
- 230000003197 catalytic effect Effects 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- XTVVROIMIGLXTD-UHFFFAOYSA-N copper(II) nitrate Chemical compound [Cu+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O XTVVROIMIGLXTD-UHFFFAOYSA-N 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 230000003993 interaction Effects 0.000 description 2
- MIVBAHRSNUNMPP-UHFFFAOYSA-N manganese(2+);dinitrate Chemical compound [Mn+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O MIVBAHRSNUNMPP-UHFFFAOYSA-N 0.000 description 2
- QGLKJKCYBOYXKC-UHFFFAOYSA-N nonaoxidotritungsten Chemical compound O=[W]1(=O)O[W](=O)(=O)O[W](=O)(=O)O1 QGLKJKCYBOYXKC-UHFFFAOYSA-N 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 239000008188 pellet Substances 0.000 description 2
- 229910052698 phosphorus Inorganic materials 0.000 description 2
- 229910052700 potassium Inorganic materials 0.000 description 2
- 239000011591 potassium Substances 0.000 description 2
- 239000001103 potassium chloride Substances 0.000 description 2
- 235000011164 potassium chloride Nutrition 0.000 description 2
- SQGYOTSLMSWVJD-UHFFFAOYSA-N silver(1+) nitrate Chemical compound [Ag+].[O-]N(=O)=O SQGYOTSLMSWVJD-UHFFFAOYSA-N 0.000 description 2
- 239000011734 sodium Substances 0.000 description 2
- JRMUNVKIHCOMHV-UHFFFAOYSA-M tetrabutylammonium bromide Chemical compound [Br-].CCCC[N+](CCCC)(CCCC)CCCC JRMUNVKIHCOMHV-UHFFFAOYSA-M 0.000 description 2
- 229910001930 tungsten oxide Inorganic materials 0.000 description 2
- 229910052720 vanadium Inorganic materials 0.000 description 2
- GPPXJZIENCGNKB-UHFFFAOYSA-N vanadium Chemical compound [V]#[V] GPPXJZIENCGNKB-UHFFFAOYSA-N 0.000 description 2
- 101710134784 Agnoprotein Proteins 0.000 description 1
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- 229910021380 Manganese Chloride Inorganic materials 0.000 description 1
- GLFNIEUTAYBVOC-UHFFFAOYSA-L Manganese chloride Chemical compound Cl[Mn]Cl GLFNIEUTAYBVOC-UHFFFAOYSA-L 0.000 description 1
- 229920000877 Melamine resin Polymers 0.000 description 1
- 229910018378 Mn(NO3)2-6H2O Inorganic materials 0.000 description 1
- 229910002651 NO3 Inorganic materials 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 239000004115 Sodium Silicate Substances 0.000 description 1
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 description 1
- 150000001337 aliphatic alkines Chemical class 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
- 239000001099 ammonium carbonate Substances 0.000 description 1
- 235000012501 ammonium carbonate Nutrition 0.000 description 1
- 150000001450 anions Chemical class 0.000 description 1
- 229910052785 arsenic Inorganic materials 0.000 description 1
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 229910017052 cobalt Inorganic materials 0.000 description 1
- 239000010941 cobalt Substances 0.000 description 1
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 1
- 239000000571 coke Substances 0.000 description 1
- 229910000365 copper sulfate Inorganic materials 0.000 description 1
- ORTQZVOHEJQUHG-UHFFFAOYSA-L copper(II) chloride Chemical compound Cl[Cu]Cl ORTQZVOHEJQUHG-UHFFFAOYSA-L 0.000 description 1
- ARUVKPQLZAKDPS-UHFFFAOYSA-L copper(II) sulfate Chemical compound [Cu+2].[O-][S+2]([O-])([O-])[O-] ARUVKPQLZAKDPS-UHFFFAOYSA-L 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 239000011964 heteropoly acid Substances 0.000 description 1
- 238000009815 homocoupling reaction Methods 0.000 description 1
- FBAFATDZDUQKNH-UHFFFAOYSA-M iron chloride Chemical compound [Cl-].[Fe] FBAFATDZDUQKNH-UHFFFAOYSA-M 0.000 description 1
- BAUYGSIQEAFULO-UHFFFAOYSA-L iron(2+) sulfate (anhydrous) Chemical compound [Fe+2].[O-]S([O-])(=O)=O BAUYGSIQEAFULO-UHFFFAOYSA-L 0.000 description 1
- VCJMYUPGQJHHFU-UHFFFAOYSA-N iron(3+);trinitrate Chemical compound [Fe+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VCJMYUPGQJHHFU-UHFFFAOYSA-N 0.000 description 1
- ZFSLODLOARCGLH-UHFFFAOYSA-N isocyanuric acid Chemical compound OC1=NC(O)=NC(O)=N1 ZFSLODLOARCGLH-UHFFFAOYSA-N 0.000 description 1
- 239000011565 manganese chloride Substances 0.000 description 1
- 235000002867 manganese chloride Nutrition 0.000 description 1
- 229940099607 manganese chloride Drugs 0.000 description 1
- SQQMAOCOWKFBNP-UHFFFAOYSA-L manganese(II) sulfate Chemical compound [Mn+2].[O-]S([O-])(=O)=O SQQMAOCOWKFBNP-UHFFFAOYSA-L 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- JDSHMPZPIAZGSV-UHFFFAOYSA-N melamine Chemical compound NC1=NC(N)=NC(N)=N1 JDSHMPZPIAZGSV-UHFFFAOYSA-N 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910017604 nitric acid Inorganic materials 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 238000006213 oxygenation reaction Methods 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- TYJJADVDDVDEDZ-UHFFFAOYSA-M potassium hydrogencarbonate Chemical compound [K+].OC([O-])=O TYJJADVDDVDEDZ-UHFFFAOYSA-M 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 229910001961 silver nitrate Inorganic materials 0.000 description 1
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 description 1
- 229910052911 sodium silicate Inorganic materials 0.000 description 1
- XMVONEAAOPAGAO-UHFFFAOYSA-N sodium tungstate Chemical compound [Na+].[Na+].[O-][W]([O-])(=O)=O XMVONEAAOPAGAO-UHFFFAOYSA-N 0.000 description 1
- 239000011973 solid acid Substances 0.000 description 1
- 239000006104 solid solution Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 150000003467 sulfuric acid derivatives Chemical class 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
Landscapes
- Exhaust Gas After Treatment (AREA)
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
- Catalysts (AREA)
Description
本発明は、希薄燃焼方式の内燃機関等から排出される排ガス中の窒素酸化物をアンモニア又はアンモニアへ加水分解可能な化合物により還元して浄化する窒素酸化物浄化用触媒、並びにその製造方法に関する。 The present invention relates to a nitrogen oxide purification catalyst that reduces and purifies nitrogen oxides in exhaust gas discharged from a lean combustion internal combustion engine or the like with ammonia or a compound that can be hydrolyzed to ammonia, and a method for producing the same.
排ガス中の窒素酸化物を除去する方法としては、排ガス中にアンモニア（ＮＨ３）を注入して窒素酸化物（ＮＯＸ）を浄化する、いわゆるＮＨ３−ＮＯＸ選択還元法が知られている。火力発電ボイラ、焼成炉、コークス炉、ガスタービンといった固定発生源においては、酸化チタンにバナジウム、タングステン、モリブデン、鉄等の元素を添加したものがいわゆるＮＯＸ選択還元触媒として主に用いられている。一方、自動車のディーゼルエンジンといった移動発生源においてもＮＨ３若しくはＮＨ３に加水分解可能な化合物（例えば、尿素）によるＮＯＸ選択還元の利用が望まれており、例えば、銅、鉄等を置換担持せしめたゼオライト触媒が検討されている。 As a method for removing nitrogen oxides in exhaust gas, a so-called NH 3 -NO X selective reduction method in which ammonia (NH 3 ) is injected into the exhaust gas to purify nitrogen oxides (NO X ) is known. . In fixed generation sources such as thermal power generation boilers, firing furnaces, coke ovens, and gas turbines, titanium oxide added with elements such as vanadium, tungsten, molybdenum, and iron is mainly used as a so-called NO X selective reduction catalyst. . On the other hand, use of NO X selective reduction by NH 3 or a compound hydrolyzable to NH 3 (for example, urea) is also desired in mobile sources such as automobile diesel engines. For example, copper, iron, etc. are substituted and supported. A fixed zeolite catalyst has been studied.
また、このようなＮＯＸ選択還元を利用した触媒として、例えば、特開２００５−８１１８９号公報（特許文献１）には、窒素酸化物を含む高温排ガス用脱硝触媒であって、酸強度がＨｏ≦−１１．３５の担体、又は、固体酸量が０．２ｍｍｏｌ／ｇ以上の担体上に、バナジウム、タングステン、モリブデン、鉄、クロム、銅、マンガン及びコバルトからなる群より選ばれる少なくとも１種以上の酸化物又はそれらの複合酸化物が担持されている高温排ガス用脱硝触媒が開示されており、明細書中において、硫酸根チタニアジルコニアに鉄等の金属が担持された高温排ガス用脱硝触媒が記載されている。また、特開２００７−１７５６３０号公報（特許文献２）には、ジルコニア担体と、前記担体に担持されているＷ及び／又はＭｏと、前記担体に担持されているＦｅとを備えるＮＯＸ選択還元触媒が開示されている。 Moreover, as a catalyst using such NO X selective reduction, for example, Japanese Patent Laying-Open No. 2005-81189 (Patent Document 1) discloses a denitration catalyst for high-temperature exhaust gas containing nitrogen oxide, which has an acid strength of Ho. ≦ -11.35 or at least one selected from the group consisting of vanadium, tungsten, molybdenum, iron, chromium, copper, manganese and cobalt on a carrier having a solid acid amount of 0.2 mmol / g or more. NOx removal catalyst for high-temperature exhaust gas in which oxides of these or their composite oxides are supported is disclosed, and in the specification, denitration catalyst for high-temperature exhaust gas in which metal such as iron is supported on sulfate titania zirconia is described Has been. Japanese Patent Application Laid-Open No. 2007-175630 (Patent Document 2) discloses NO X selective reduction comprising a zirconia support, W and / or Mo supported on the support, and Fe supported on the support. A catalyst is disclosed.
しかしながら、上記特許文献等に記載のような触媒は、高温域（例えば、４００〜７００℃）においては十分なＮＯＸ浄化活性を有するものの、低温域（例えば、２００〜２５０℃）におけるＮＯＸ浄化活性が必ずしも十分なものではなかった。
本発明は、上記従来技術の有する課題に鑑みてなされたものであり、低温域（例えば、２００〜２５０℃）においても十分なＮＯＸ浄化活性を有する窒素酸化物浄化用触媒、並びにその製造方法を提供することを目的とする。 The present invention has been made in view of the above-described problems of the prior art, and a nitrogen oxide purification catalyst having sufficient NO x purification activity even in a low temperature range (for example, 200 to 250 ° C.), and a method for producing the same. The purpose is to provide.
本発明者は、上記目的を達成すべく鋭意研究を重ねた結果、内燃機関から排出される窒素酸化物をアンモニア又はアンモニアへ加水分解可能な化合物により還元する窒素酸化物浄化用触媒として、セリアを主成分とする担体と、タングステン及びモリブデンからなる群から選択される少なくとも１種の第一金属元素並びに鉄、銅及びマンガンからなる群から選択される少なくとも１種の第二金属元素とを組み合わせた触媒を用いることにより、排ガスの温度条件が低温域にある場合においても極めて高いＮＯＸ浄化活性を達成できることを見出し、本発明を完成するに至った。 As a result of intensive studies to achieve the above object, the present inventor has found ceria as a nitrogen oxide purification catalyst that reduces nitrogen oxides discharged from an internal combustion engine with ammonia or a compound that can be hydrolyzed to ammonia. The carrier as a main component is combined with at least one first metal element selected from the group consisting of tungsten and molybdenum and at least one second metal element selected from the group consisting of iron, copper and manganese. by using the catalyst, the temperature condition of the exhaust gas heading to be able to achieve very high NO X purification activity even when in the low temperature range, and have completed the present invention.
すなわち、本発明の窒素酸化物浄化用触媒は、内燃機関から排出される窒素酸化物をアンモニア又はアンモニアへ加水分解可能な化合物により還元する窒素酸化物浄化用触媒であって、セリアを主成分とするセリア含有担体と、前記担体に担持されているタングステン及びモリブデンからなる群から選択される少なくとも１種の第一金属元素と、前記担体に担持されている鉄、銅及びマンガンからなる群から選択される少なくとも１種の第二金属元素と、前記担体に担持されているケイ素とを備えることを特徴とするものである。
That is, the catalyst for purifying nitrogen oxides of the present invention is a catalyst for purifying nitrogen oxides that reduces nitrogen oxides discharged from an internal combustion engine with ammonia or a compound that can be hydrolyzed to ammonia, and contains ceria as a main component. Selected from the group consisting of iron, copper and manganese supported on the support, at least one first metal element selected from the group consisting of tungsten and molybdenum supported on the support And at least one second metal element and silicon supported on the carrier .
また、上記本発明の窒素酸化物浄化用触媒においては、前記第一金属元素の担持量が、前記窒素酸化物浄化用触媒の全質量に対して金属換算で１〜６０質量％の範囲であることが好ましい。 In the nitrogen oxide purification catalyst of the present invention, the amount of the first metal element supported is in the range of 1 to 60 mass% in terms of metal with respect to the total mass of the nitrogen oxide purification catalyst. It is preferable.
さらに、上記本発明の窒素酸化物浄化用触媒においては、前記第二金属元素の担持量が、前記窒素酸化物浄化用触媒の全質量に対して金属換算で０．１〜１５質量％の範囲であることが好ましい。 Further, in the nitrogen oxide purification catalyst of the present invention, the supported amount of the second metal element is in a range of 0.1 to 15% by mass in terms of metal with respect to the total mass of the nitrogen oxide purification catalyst. It is preferable that
また、上記本発明の窒素酸化物浄化用触媒においては、前記第一金属元素と前記第二金属元素とを含有する酸化物クラスターが、前記セリア含有担体に担持されていることが好ましい。 In the nitrogen oxide purifying catalyst of the present invention, an oxide cluster containing the first metal element and the second metal element is preferably supported on the ceria-containing support.
さらに、上記本発明の窒素酸化物浄化用触媒においては、前記酸化物クラスターが、前記第一金属元素の酸化物クラスターのうちの金属原子が前記第二金属元素の原子に置換された二置換型酸化物クラスターであることが好ましい。 Furthermore, in the nitrogen oxide purification catalyst of the present invention, the oxide cluster is a disubstituted type in which a metal atom in the oxide cluster of the first metal element is replaced with an atom of the second metal element. An oxide cluster is preferred.
本発明の窒素酸化物浄化用触媒の製造方法は、内燃機関から排出される窒素酸化物をアンモニア又はアンモニアへ加水分解可能な化合物により還元する窒素酸化物浄化用触媒の製造方法であって、タングステン及びモリブデンからなる群から選択される少なくとも１種の第一金属元素と、鉄、銅及びマンガンからなる群から選択される少なくとも１種の第二金属元素と、ケイ素とを、セリアを主成分とするセリア含有担体に担持せしめて前記窒素酸化物浄化用触媒を得ることを特徴とする方法である。
The method for producing a nitrogen oxide purifying catalyst of the present invention is a method for producing a nitrogen oxide purifying catalyst for reducing nitrogen oxide discharged from an internal combustion engine with ammonia or a compound that can be hydrolyzed to ammonia, comprising tungsten And at least one first metal element selected from the group consisting of molybdenum, at least one second metal element selected from the group consisting of iron, copper and manganese , silicon, and ceria as a main component. The above-mentioned catalyst for purifying nitrogen oxides is obtained by being supported on a ceria-containing support.
また、上記本発明の窒素酸化物浄化用触媒の製造方法においては、前記第一金属元素と前記第二金属元素とを含有する酸化物クラスターを、前記セリア含有担体に担持せしめることが好ましい。 In the method for producing a catalyst for purifying nitrogen oxides according to the present invention, it is preferable that an oxide cluster containing the first metal element and the second metal element is supported on the ceria-containing support.
さらに、上記本発明の窒素酸化物浄化用触媒の製造方法においては、前記酸化物クラスターが、前記第一金属元素の酸化物クラスターのうちの金属原子が前記第二金属元素の原子に置換された二置換型酸化物クラスターであることが好ましい。 Further, in the above method for producing a catalyst for purifying nitrogen oxides of the present invention, the metal cluster in the oxide cluster of the first metal element is substituted with the atom of the second metal element in the oxide cluster. A disubstituted oxide cluster is preferred.
本発明によれば、低温域（例えば、２００〜２５０℃）においても十分なＮＯＸ浄化活性を有する窒素酸化物浄化用触媒、並びにその製造方法を提供することが可能となる。 According to the present invention, it is possible to provide a nitrogen oxide purification catalyst having sufficient NO x purification activity even in a low temperature range (for example, 200 to 250 ° C.) and a method for producing the same.
以下、本発明をその好適な実施形態に即して詳細に説明する。 Hereinafter, the present invention will be described in detail with reference to preferred embodiments thereof.
本発明の窒素酸化物浄化用触媒は、内燃機関から排出される窒素酸化物をアンモニア又はアンモニアへ加水分解可能な化合物により還元する窒素酸化物浄化用触媒であって、
セリアを主成分とするセリア含有担体と、前記担体に担持されているタングステン及びモリブデンからなる群から選択される少なくとも１種の第一金属元素と、前記担体に担持されている鉄、銅及びマンガンからなる群から選択される少なくとも１種の第二金属元素とを備えるものである。
The nitrogen oxide purification catalyst of the present invention is a nitrogen oxide purification catalyst that reduces nitrogen oxides discharged from an internal combustion engine with ammonia or a compound that can be hydrolyzed to ammonia,
A ceria-containing support containing ceria as a main component, at least one first metal element selected from the group consisting of tungsten and molybdenum supported on the support, and iron, copper, and manganese supported on the support And at least one second metal element selected from the group consisting of:
本発明にかかるセリア含有担体は、セリア（ＣｅＯ２）を主成分として含有するものである。このようなセリア含有担体は、セリアのみからなる担体であってもよく、あるいはセリアとセリア以外の他の金属酸化物とを含有する担体であってもよい。このようなセリア含有担体に含有されていてもよいセリア以外の他の金属酸化物としては、窒素酸化物浄化用触媒の担体に用いることが可能な金属酸化物であればよく特に制限されず、例えば、ジルコニア、アルミナ、セリア以外の希土類元素の酸化物が挙げられる。また、このような他の金属酸化物を含有するセリア含有担体としては、セリアと他の金属酸化物の混合物、セリアと他の金属酸化物の固溶体、セリアと他の金属酸化物の複合酸化物等が挙げられる。また、このようなセリア含有担体におけるＣｅＯ２の含有量は、セリア含有担体中の金属元素に対するＣｅの比率が５０モル％以上（より好ましくは７０モル％以上）となる量であることが好ましい。ＣｅＯ２の含有量が５０モル％未満では、セリアとタングステン及び／又はモリブデンとの相互作用が十分に発現しないため、得られる窒素酸化物浄化用触媒の低温域におけるＮＯＸ浄化活性が不十分となる傾向にある。 The ceria-containing carrier according to the present invention contains ceria (CeO 2 ) as a main component. Such a ceria-containing support may be a support composed of ceria alone, or may be a support containing ceria and a metal oxide other than ceria. The metal oxide other than ceria that may be contained in such a ceria-containing support is not particularly limited as long as it is a metal oxide that can be used as a support for a catalyst for purifying nitrogen oxides. Examples thereof include oxides of rare earth elements other than zirconia, alumina, and ceria. The ceria-containing support containing such other metal oxides includes a mixture of ceria and other metal oxides, a solid solution of ceria and other metal oxides, and a composite oxide of ceria and other metal oxides. Etc. Further, the CeO 2 content in such a ceria-containing support is preferably such an amount that the ratio of Ce to the metal element in the ceria-containing support is 50 mol% or more (more preferably 70 mol% or more). When the content of CeO 2 is less than 50 mol%, the interaction between ceria and tungsten and / or molybdenum is not sufficiently expressed, and therefore the obtained NOx purification catalyst has insufficient NO X purification activity in the low temperature range. Tend to be.
また、このようなセリア含有担体の形状は特に制限されないが、高い比表面積が得られるという観点から、粉末状であることが好ましい。また、このようなセリア含有担体の比表面積は特に制限されないが、より高い触媒活性を得るという観点からは、３０ｍ２／ｇ以上（より好ましくは５０〜１５０ｍ２／ｇ）であることがより好ましい。なお、このようなセリア含有担体の製造方法は特に制限されず、公知の方法を適宜採用することができる。さらに、このようなセリア含有担体としては、市販のものを用いてもよい。 In addition, the shape of such a ceria-containing support is not particularly limited, but is preferably a powder from the viewpoint of obtaining a high specific surface area. Further, the specific surface area of such a ceria-containing support is not particularly limited, but is preferably 30 m 2 / g or more (more preferably 50 to 150 m 2 / g) from the viewpoint of obtaining higher catalytic activity. . In addition, the manufacturing method in particular of such a ceria containing support | carrier is not restrict | limited, A well-known method is employable suitably. Furthermore, as such a ceria-containing carrier, a commercially available product may be used.
また、本発明の窒素酸化物浄化用触媒においては、低温域において高水準のＮＯＸ浄化活性を達成するという観点から、前記セリア含有担体に後述する第一金属元素並びに後述する第二金属元素が担持されていることが必要である。本発明においては、セリアと前記第一金属元素とが相互作用することにより、前記第一金属元素の近傍又は前記第一金属元素上に担持された前記第二金属元素の原子がより一層活性化されるため、低温域においても高水準のＮＯＸ浄化活性が達成されるようになるものと推察される。 In the nitrogen oxide purification catalyst of the present invention, from the viewpoint of achieving a high level of the NO X purification activity at low temperature range, the second metal element first metal element and later it will be described later in the ceria-containing carrier It must be supported. In the present invention, ceria and the first metal element interact to further activate the atoms of the second metal element supported in the vicinity of the first metal element or on the first metal element. to be, it is presumed to be as high of the NO X purification activity is achieved even at a low temperature region.
また、このような第一金属元素は、タングステン及びモリブデンからなる群から選択される少なくとも１種の金属元素である。このような第一金属元素の担持量としては、前記窒素酸化物浄化用触媒の全質量に対して金属換算で１〜６０質量％の範囲であることが好ましく、５〜４０質量％の範囲であることがより好ましい。このような第一金属元素の担持量が前記下限未満では、セリアと第一金属元素（タングステン及び／又はモリブデン）との相互作用が十分に発現しないため、得られる窒素酸化物浄化用触媒の低温域におけるＮＯＸ浄化活性が不十分となる傾向にあり、他方、前記上限を超えると触媒の比表面積が低下するため、得られる窒素酸化物浄化用触媒の低温域におけるＮＯＸ浄化活性が不十分となる傾向にある。 Such a first metal element is at least one metal element selected from the group consisting of tungsten and molybdenum. The amount of the first metal element supported is preferably in the range of 1 to 60% by mass in terms of metal with respect to the total mass of the nitrogen oxide purifying catalyst, and in the range of 5 to 40% by mass. More preferably. When the amount of the first metal element supported is less than the lower limit, the interaction between ceria and the first metal element (tungsten and / or molybdenum) is not sufficiently developed. tend to have NO X purification activity in band become insufficient, while the specific surface area of the catalyst exceeds the above upper limit decreases, insufficient NO X purification activity at low-temperature region of the nitrogen oxide purifying catalyst obtained It tends to be.
さらに、前記第二金属元素は、鉄、銅及びマンガンからなる群から選択される少なくとも１種の金属元素である。このような第二金属元素としては、より高い触媒活性が得られるという観点から、鉄がより好ましい。また、このような第二金属元素の担持量としては、前記窒素酸化物浄化用触媒の全質量に対して金属換算で０．１〜１５質量％の範囲であることが好ましく、１〜１０質量％の範囲であることがより好ましい。前記第二金属元素の担持量が前記下限未満では、前記第二金属元素に由来する触媒の活性点の数が少なくなるため、得られる窒素酸化物浄化用触媒の低温域におけるＮＯＸ浄化活性が不十分となる傾向にあり、他方、前記上限を超えると反応に不活性な前記第二金属元素の酸化物結晶（例えばＦｅ２Ｏ３の結晶等）が形成されるため、得られる窒素酸化物浄化用触媒の低温域におけるＮＯＸ浄化活性が不十分となる傾向にある。 Furthermore, the second metal element is at least one metal element selected from the group consisting of iron, copper and manganese. As such a second metal element, iron is more preferable from the viewpoint of obtaining higher catalytic activity. The amount of the second metal element supported is preferably in the range of 0.1 to 15% by mass in terms of metal with respect to the total mass of the nitrogen oxide purifying catalyst. % Is more preferable. Wherein in the supported amount of the second metal element is less than the lower limit, the second for the number of active sites of the catalyst derived from the metal element is reduced, the NO X purification activity at low-temperature region of the nitrogen oxide purifying catalyst obtained On the other hand, the oxide of the second metal element (eg, Fe 2 O 3 crystal) that is inactive to the reaction when the upper limit is exceeded is formed. NO X purification activity at low-temperature region of the purifying catalyst tends to be insufficient.
このような本発明の窒素酸化物浄化用触媒は、タングステン及びモリブデンからなる群から選択される少なくとも１種の前記第一金属元素と、鉄、銅及びマンガンからなる群から選択される少なくとも１種の前記第二金属元素とを、セリアを主成分とするセリア含有担体に担持せしめることにより得ることができる。このように、前記セリア含有担体に前記第一金属元素及び前記第二金属元素を担持せしめる方法としては、例えば、（i）タングステン源及びモリブデン源からなる群から選択させる少なくとも１種の第一金属元素源並びに鉄源、銅源及びマンガン源からなる群から選択される少なくとも１種の第二金属元素源を含有する水溶液に前記セリア含有担体を含浸させて前記第一金属元素源並びに前記第二金属元素源を前記担体に担持せしめた後に焼成する方法、（ii）前記第一金属元素源並びに前記第二金属元素源、さらには前記セリア含有担体を物理混合して焼成する方法を採用することができる。これらの方法の中でも、前記第一金属元素及び前記第二金属元素を高分散にセリア含有担体上に担持するという観点から、前記第一金属元素源及び前記第二金属元素源を含有する水溶液に前記セリア含有担体を含浸させて前記第一金属元素源及び前記第二金属元素源を前記担体に担持せしめた後に焼成する方法が好ましい。また、このような方法において、焼成温度は３００〜６００℃の範囲であることが好ましく、焼成時間は１〜５時間の範囲であることが好ましい。 Such a nitrogen oxide purifying catalyst of the present invention is at least one selected from the group consisting of at least one first metal element selected from the group consisting of tungsten and molybdenum, and iron, copper and manganese. The second metal element can be obtained by supporting the second metal element on a ceria-containing support containing ceria as a main component. Thus, as a method for supporting the first metal element and the second metal element on the ceria-containing support, for example, (i) at least one first metal selected from the group consisting of a tungsten source and a molybdenum source is used. An aqueous solution containing at least one second metal element source selected from the group consisting of an element source and an iron source, a copper source, and a manganese source is impregnated with the ceria-containing support, and the first metal element source and the second source. A method of firing after supporting the metal element source on the carrier, (ii) adopting a method of firing by physically mixing the first metal element source and the second metal element source, and further the ceria-containing carrier. Can do. Among these methods, from the viewpoint of supporting the first metal element and the second metal element on a ceria-containing support in a highly dispersed manner, the aqueous solution containing the first metal element source and the second metal element source is used. A method in which the ceria-containing support is impregnated and the first metal element source and the second metal element source are supported on the support and then fired is preferable. In such a method, the firing temperature is preferably in the range of 300 to 600 ° C., and the firing time is preferably in the range of 1 to 5 hours.
さらに、このような第一金属元素源としては、第一金属元素の塩であればよく、特に限定されないが、例えば、１原子の塩（例えば、ＨＷＯ４、Ｈ２ＭｏＯ４）、ポリ酸塩（例えば、（ＮＨ４）１０Ｗ１２Ｏ４１、（ＮＨ４）６Ｍｏ７Ｏ２４）、ＰやＳｉを含むヘテロポリ酸塩（例えば、Ｈ３ＰＷ１２Ｏ４０、Ｈ３ＰＭｏ１２Ｏ４０、Ｈ４ＳｉＷ１２Ｏ４０、Ｈ４ＳｉＭｏ１２Ｏ４０）が挙げられる。 Further, the first metal element source is not particularly limited as long as it is a salt of the first metal element. For example, a salt of one atom (for example, HWO 4 , H 2 MoO 4 ), a polyacid salt (For example, (NH 4 ) 10 W 12 O 41 , (NH 4 ) 6 Mo 7 O 24 ), heteropoly acid salts containing P and Si (for example, H 3 PW 12 O 40 , H 3 PMo 12 O 40 , H 4 SiW 12 O 40 , H 4 SiMo 12 O 40 ).
また、このような前記第二金属元素源としては、前記第二金属元素の塩であればよく、特に限定されないが、硝酸塩（例えば、硝酸鉄［Ｆｅ（ＮＯ３）３］、硝酸銅［Ｃｕ（ＮＯ３）２］、硝酸マンガン［Ｍｎ（ＮＯ３）２］）、ハロゲン塩（例えば、塩化鉄［ＦｅＣｌ２、ＦｅＣｌ３］、塩化銅［ＣｕＣｌ４、ＣｕＣｌ２、ＣｕＣｌ等］、塩化マンガン［ＭｎＣｌ２等］）、硫酸塩（例えば、硫酸鉄［ＦｅＳＯ４］、硫酸銅［ＣｕＳＯ４］、硫酸マンガン［ＭｎＳＯ４］）等が挙げられる。 The second metal element source is not particularly limited as long as it is a salt of the second metal element. For example, a nitrate (eg, iron nitrate [Fe (NO 3 ) 3 ], copper nitrate [Cu (NO 3 ) 2 ], manganese nitrate [Mn (NO 3 ) 2 ]), halogen salts (eg, iron chloride [FeCl 2 , FeCl 3 ], copper chloride [CuCl 4 , CuCl 2 , CuCl, etc.]), manganese chloride [ MnCl 2 etc.), sulfates (eg, iron sulfate [FeSO 4 ], copper sulfate [CuSO 4 ], manganese sulfate [MnSO 4 ]) and the like.
さらに、このようにセリア含有担体に前記第一金属元素及び前記第二金属元素を担持せしめる方法においては、前記第一金属元素及び前記第二金属元素を同時にセリア含有担体に担持することが好ましく、前記第一金属元素及び前記第二金属元素を含有する酸化物クラスターをセリア含有担体に担持することがより好ましい。このように前記第一金属元素及び前記第二金属元素を含有する酸化物クラスターをセリア含有担体に担持せしめることにより、低温域におけるＮＯＸ浄化活性がより向上した窒素酸化物浄化用触媒を効率よく得ることができる。すなわち、このようにして得られる本発明の窒素酸化物浄化用触媒としては、より高度なＮＯＸ浄化活性を得るという観点から、前記第一金属元素及び前記第二金属元素を含有する酸化物クラスターが前記セリア含有担体に担持されていることが好ましい。 Further, in the method of supporting the first metal element and the second metal element on the ceria-containing support in this way, it is preferable to simultaneously support the first metal element and the second metal element on the ceria-containing support, More preferably, the oxide cluster containing the first metal element and the second metal element is supported on a ceria-containing support. By allowed to carry the oxide clusters containing this way the first metal element and said second metal element ceria-containing carrier, efficiently removing nitrogen oxide catalyst for a more enhanced NO X purification activity at low temperature range Can be obtained. That is, the nitrogen oxide purification catalyst of the present invention thus obtained, from the viewpoint of obtaining a higher degree of NO X purification activity, oxide clusters containing the first metallic element and said second metal element Is preferably supported on the ceria-containing support.
また、このような酸化物クラスターは、前記第一金属元素及び前記第二金属元素を含有する酸化物クラスターであればよく、特に限定されない。ここで、酸化物クラスターとは、タングステン、モリブデン、鉄、銅、マンガン、酸素等の原子が集まり、それらの一部若しくは全体が直接結合することによって形成される数個から数十個の原子集団のことをいう。また、このような酸化物クラスターは、タングステン、モリブデン、鉄、銅、マンガン及び酸素以外の原子（例えば、ケイ素、リン、ヒ素）を含有していてもよい。さらに、このような酸化物クラスターは、得られる窒素酸化物浄化用触媒のＮＯＸ浄化活性の観点から、前記第一金属元素の酸化物クラスターのうちの金属原子が前記第二金属元素の原子に置換された二置換型酸化物クラスターであることが好ましい。このような二置換型酸化物クラスターとしては、例えば、図１に示す鉄二置換型酸化物クラスターのように、タングステンの酸化物クラスターにおけるタングステン原子のうちの２つの原子が鉄原子に置換されている二置換型酸化物クラスターが挙げられる。また、このような酸化物クラスターにおいては、より高い活性が得られるという観点から、そのクラスター中において前記第二金属元素が二核構造を形成していることがより好ましい。 Such an oxide cluster is not particularly limited as long as it is an oxide cluster containing the first metal element and the second metal element. Here, an oxide cluster is a group of several to several tens of atoms formed by gathering atoms such as tungsten, molybdenum, iron, copper, manganese, oxygen, etc., and part or all of them directly bonding I mean. Such an oxide cluster may contain atoms (for example, silicon, phosphorus, arsenic) other than tungsten, molybdenum, iron, copper, manganese, and oxygen. Further, such an oxide clusters, in terms of the NO X purification activity of nitrogen oxide purifying catalyst obtained, the metal atom is atom of the second metal element of the oxide clusters of the first metal element A substituted disubstituted oxide cluster is preferred. As such a disubstituted oxide cluster, for example, as in the iron disubstituted oxide cluster shown in FIG. 1, two of the tungsten atoms in the tungsten oxide cluster are substituted with iron atoms. A disubstituted oxide cluster is mentioned. Moreover, in such an oxide cluster, it is more preferable that the second metal element forms a binuclear structure in the cluster from the viewpoint of obtaining higher activity.
このような酸化物クラスターを製造する方法としては特に制限されないが、例えば、前記第一金属元素の酸化物クラスターのうちの金属原子が鉄原子に置換されている二置換型酸化物クラスター（鉄二置換型酸化物クラスター）を製造する場合には、例えば、「Ｊ． Ａｍ． Ｃｈｅｍ． Ｓｏｃ．」、１９９８年発行、１２０巻９２６７〜９２７２頁の「Ｈｉｇｈｌｙ Ｅｆｆｉｃｉｅｎｔ Ｕｔｉｌｉｚａｔｉｏｎ ｏｆ Ｈｙｄｒｏｇｅｎ Ｐｅｒｏｘｉｄｅ ｆｏｒ Ｓｅｌｅｃｔｉｖｅ Ｏｘｙｇｅｎａｔｉｏｎ ｏｆ Ａｌｋａｎｅｓ Ｃａｔａｌｙｚｅｄ ｂｙ Ｄｉｉｒｏｎ−Ｓｕｂｓｔｉｔｕｔｅｄ Ｐｏｌｙｏｘｏｍｅｔａｌａｔｅ Ｐｒｅｃｕｒｓｏｒ」に記載されている方法を採用することができる。また、前記第一金属元素の酸化物クラスターのうちの金属原子がマンガン原子に置換されている二置換型酸化物クラスター（マンガン二置換型酸化物クラスター）を製造する場合には、「Ｉｎｏｒｇ． Ｃｈｅｍ．」、１９９６年発行、Ｖｏｌ．３５、３０−３４頁の「Ｈｉｇｈ−Ｖａｌｅｎｔ Ｍａｎｇａｎｅｓｅ ｉｎ Ｐｏｌｙｏｘｏｔｕｎｇｓｔａｔｅｓ． ３． Ｄｉｍａｎｇａｎｅｓｅ Ｃｏｍｐｌｅｘｅｓ ｏｆ γ−Ｋｅｇｇｉｎ Ａｎｉｏｎｓ」に記載されている方法を採用することができる。更に、前記第一金属元素の酸化物クラスターのうちの金属原子が銅原子に置換されている二置換型酸化物クラスター（銅二置換型酸化物クラスター）を製造する場合には、「Ａｎｇｅｗ． Ｃｈｅｍ． Ｉｎｔ． Ｅｄ．」、２００８年発行、Ｖｏｌ．４７、２４０７−２４１０頁の「Ｅｆｆｉｃｉｅｎｔ Ｏｘｉｄａｔｉｖｅ Ａｌｋｙｎｅ Ｈｏｍｏｃｏｕｐｌｉｎｇ Ｃａｔａｌｙｚｅｄ ｂｙ ａ Ｍｏｎｏｍｅｒｉｃ Ｄｉｃｏｐｐｅｒ−Ｓｕｂｓｔｉｔｕｔｅｄ Ｓｉｌｉｃｏｔｕｎｇｓｔａｔｅ」に記載されている方法を採用することができる。また、このような酸化物クラスターの製造方法としては、より具体的には、欠陥サイトを２つ有するポリタングステン酸又はポリモリブデン酸を合成し、その欠陥サイトに前記第二金属元素の原子を置換する方法を挙げることができる。 A method for producing such an oxide cluster is not particularly limited. For example, a disubstituted oxide cluster in which a metal atom in the oxide cluster of the first metal element is substituted with an iron atom (iron disubstituted) For example, “J. Am. Chem. Soc.”, Published in 1998, Volume 120, pages 9267-9272, “Highly Efficient Utilization of Hydroxygen for Oxygenated Oxygenation”. The method described in “Diiron-Substituted Polyoxomate Precursor” can be employed. In the case of producing a disubstituted oxide cluster (manganese disubstituted oxide cluster) in which the metal atom in the oxide cluster of the first metal element is substituted with a manganese atom, “Inorg. Chem. , "1996, Vol. 35, pages 30 to 34, “High-Valent Manganese in Polyoxountstates. 3. Dimanage Complexes of γ-Keggin Anions” can be employed. Furthermore, when manufacturing a disubstituted oxide cluster (copper disubstituted oxide cluster) in which metal atoms in the oxide cluster of the first metal element are substituted with copper atoms, “Angew. Int. Ed. ", 2008, Vol. 47, 2407-2410, “Efficient Oxidative Alkine Homocoupling Catalyzed by a Monomeric Dicopper—Substituted Silicone State” can be employed. Further, as a method for producing such an oxide cluster, more specifically, polytungstic acid or polymolybdic acid having two defect sites is synthesized, and the atoms of the second metal element are substituted at the defect sites. The method of doing can be mentioned.
以上説明した本発明の窒素酸化物浄化用触媒の形状としては、特に限定されないが、例えば、粉粒状、粒状、ペレット状、ハニカム状が挙げられる。また、本発明の窒素酸化物浄化用触媒は、非多孔質であってもよく、多孔質であってもよい。 The shape of the nitrogen oxide purifying catalyst of the present invention described above is not particularly limited, and examples thereof include powder, granule, pellet, and honeycomb. Further, the nitrogen oxide purifying catalyst of the present invention may be non-porous or porous.
また、本発明の窒素酸化物浄化用触媒を用いて内燃機関から排出される窒素酸化物をアンモニア又はアンモニアへ加水分解可能な化合物により還元する方法としては、特に制限されず公知の方法を適宜選択することができる。このようなアンモニアへ加水分解可能な化合物としては、例えば、尿素、シアヌル酸、メラミン、炭酸アンモニウムが挙げられる。また、このような方法においては、本発明の窒素酸化物浄化用触媒の他に公知のＮＯＸ選択還元触媒を併せて用いることができる。 Further, the method for reducing nitrogen oxides discharged from the internal combustion engine using the nitrogen oxide purifying catalyst of the present invention with ammonia or a compound hydrolyzable to ammonia is not particularly limited, and a known method is appropriately selected. can do. Examples of such a compound that can be hydrolyzed to ammonia include urea, cyanuric acid, melamine, and ammonium carbonate. In such a method, a known NO X selective reduction catalyst can be used in addition to the nitrogen oxide purifying catalyst of the present invention.
以下、実施例及び比較例に基づいて本発明をより具体的に説明するが、本発明は以下の実施例に限定されるものではない。 EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example.
（実施例１）
ケイタングステン酸（Ｈ４ＳｉＷ１２Ｏ４０ ２４Ｈ２Ｏ）０．８６ｍｍｏｌと硝酸鉄（Ｆｅ（ＮＯ３）３ ９Ｈ２Ｏ）１．７２ｍｍｏｌを１００ｍｌのイオン交換水に溶解し、そこへＣｅＯ２粉末（比表面積１６０ｍ２／ｇ）３ｇを含浸せしめ、９０℃で加熱攪拌して蒸発乾燥させて凝固物を得た。得られた凝固物を大気中において５００℃で焼成した後、１０００ｋｇｆ／ｃｍ２で圧粉成型し、破砕、整粒して直径０．５〜１．０ｍｍのペレット化された窒素酸化物浄化用触媒（以下、場合により「ＮＯＸ浄化用触媒」という）を得た。得られたＮＯＸ浄化用触媒において、Ｗ及びＦｅの担持量はＮＯＸ浄化用触媒の全質量に対して金属換算でそれぞれ３４．４質量％及び１．７質量％であった。なお、得られたＮＯＸ浄化用触媒の担体種及び前記担体に担持させた金属塩の種類及び担体に担持させた金属種の担持量を表１に示す。
Example 1
Silicotungstic acid (H 4 SiW 12 O 40 24H 2 O) 0.86 mmol and iron nitrate (Fe (NO 3 ) 3 9H 2 O) 1.72 mmol were dissolved in 100 ml of ion-exchanged water, and then CeO 2 powder ( 3 g of a specific surface area of 160 m 2 / g) was impregnated, heated and stirred at 90 ° C., and evaporated to dryness to obtain a solidified product. After the obtained solidified product is baked at 500 ° C. in the air, it is compacted at 1000 kgf / cm 2 , crushed and sized, and purified into pellets of 0.5 to 1.0 mm in diameter. A catalyst (hereinafter referred to as “NO X purification catalyst” in some cases) was obtained. In the obtained NO X purification catalyst, the supported amounts of W and Fe were 34.4 mass% and 1.7 mass%, respectively, in terms of metal with respect to the total mass of the NO X purification catalyst. In addition, Table 1 shows the carrier type of the obtained NO X purification catalyst, the type of metal salt supported on the carrier, and the amount of metal species supported on the carrier.
（実施例２）
タングステン酸ナトリウム（Ｎａ２ＷＯ４ ２Ｈ２Ｏ）５５ｍｍｏｌを３０ｍｌのイオン交換水に溶解した水溶液に塩酸を加えてｐＨを５〜６の範囲に調整した後、珪酸ナトリウム（Ｎａ２ＳｉＯ３ ９Ｈ２Ｏ）５ｍｍｏｌを加えて１００分間攪拌し、塩化カリウム９ｇを入れて、生成した沈殿をろ過、乾燥させて沈殿物を得た。得られた沈殿物を再度４０ｍｌのイオン交換水に溶解させ、炭酸カリウム水溶液を加えてｐＨを９．１に調整した後に１５分間攪拌し、次いで塩化カリウム１０ｇを加えて生成した沈殿をろ過することにより、特定構造のケイタングステン酸カリウム塩水和物（Ｋ８ＳｉＷ１０Ｏ３６ １２Ｈ２Ｏ）を得た。得られたケイタングステン酸カリウム塩水和物（Ｋ８ＳｉＷ１０Ｏ３６ １２Ｈ２Ｏ）１ｍｍｏｌを３０ｍｌのイオン交換水に溶解し、硝酸でｐＨを３．９に調整した後、硝酸鉄（Ｆｅ（ＮＯ３）３ ９Ｈ２Ｏ）２ｍｍｏｌを加えて５分間攪拌した後、テトラブチルアンモニウムブロミド（ＴＢＡＢｒ）１０ｍｍｏｌを加えて生成した沈殿をろ過することにより、鉄二置換型酸化物クラスター［ＳｉＷ１０｛Ｆｅ（ＯＨ２）｝２Ｏ３８］６−の塩を得た。得られた鉄二置換型酸化物クラスター０．８５ｍｍｏｌを５０ｍｌのアセトニトリルに溶解し、そこへＣｅＯ２粉末（比表面積１６０ｍ２／ｇ）３ｇを加えた後、ロータリーエバポレーターを用いて溶媒を除去することにより、鉄二置換型酸化物クラスターをＣｅＯ２粉末に固定化せしめた。鉄二置換型酸化物クラスターが固定化されたＣｅＯ２粉末を大気中において５００℃で焼成した後、１０００ｋｇｆ／ｃｍ２で圧粉成型し、破砕、整粒して直径０．５〜１．０ｍｍのペレット化されたＮＯＸ浄化用触媒を得た。得られたＮＯＸ浄化用触媒において、Ｗ及びＦｅの担持量はＮＯＸ浄化用触媒の全質量に対して金属換算でそれぞれ３０．０質量％及び１．８質量％であった。なお、得られたＮＯＸ浄化用触媒の担体種及び前記担体に担持させた金属塩の種類及び担体に担持させた金属種の担持量を表１に示す。
(Example 2)
Hydrochloric acid was added to an aqueous solution in which 55 mmol of sodium tungstate (Na 2 WO 4 2H 2 O) was dissolved in 30 ml of ion-exchanged water to adjust the pH to a range of 5 to 6, and then sodium silicate (Na 2 SiO 3 9H 2 O). ) 5 mmol was added and stirred for 100 minutes, 9 g of potassium chloride was added, and the produced precipitate was filtered and dried to obtain a precipitate. The resulting precipitate is dissolved again in 40 ml of ion-exchanged water, adjusted to pH 9.1 by adding an aqueous potassium carbonate solution, stirred for 15 minutes, and then filtered by 10 g of potassium chloride. To obtain potassium silicotungstate hydrate (K 8 SiW 10 O 36 12H 2 O) having a specific structure. 1 mmol of the obtained potassium silicotungstate hydrate (K 8 SiW 10 O 36 12H 2 O) was dissolved in 30 ml of ion-exchanged water, and the pH was adjusted to 3.9 with nitric acid, and then iron nitrate (Fe (NO 3 ) After adding 3 mmol of 3 9H 2 O) and stirring for 5 minutes, the precipitate formed by adding 10 mmol of tetrabutylammonium bromide (TBABr) was filtered to obtain an iron disubstituted oxide cluster [SiW 10 {Fe (OH 2 )} 2 O 38 ] 6- salt was obtained. By dissolving 0.85 mmol of the obtained iron disubstituted oxide cluster in 50 ml of acetonitrile, adding 3 g of CeO 2 powder (specific surface area 160 m 2 / g) thereto, and then removing the solvent using a rotary evaporator. The iron disubstituted oxide cluster was immobilized on CeO 2 powder. After firing CeO 2 powder in which iron disubstituted oxide clusters are immobilized at 500 ° C. in the air, it is compacted at 1000 kgf / cm 2 , crushed and sized, and has a diameter of 0.5 to 1.0 mm. A pelletized NO X purification catalyst was obtained. In the obtained NO X purification catalyst, the supported amounts of W and Fe were 30.0 mass% and 1.8 mass%, respectively, in terms of metal with respect to the total mass of the NO X purification catalyst. In addition, Table 1 shows the carrier type of the obtained NO X purification catalyst, the type of metal salt supported on the carrier, and the amount of metal species supported on the carrier.
（実施例３）
ケイタングステン酸に代えてケイモリブデン酸（Ｈ４ＳｉＭｏ１２Ｏ４０）を用いた以外は実施例１と同様にして、ＮＯＸ浄化用触媒を得た。得られたＮＯＸ浄化用触媒において、Ｍｏ及びＦｅの担持量はＮＯＸ浄化用触媒の全質量に対して金属換算でそれぞれ２１．２質量％及び２．１質量％であった。なお、得られたＮＯＸ浄化用触媒の担体種及び前記担体に担持させた金属塩の種類及び担体に担持させた金属種の担持量を表１に示す。
(Example 3)
A NO x purification catalyst was obtained in the same manner as in Example 1 except that silicomolybdic acid (H 4 SiMo 12 O 40 ) was used instead of silicotungstic acid. In the obtained NO X purification catalyst, the supported amounts of Mo and Fe were 21.2 mass% and 2.1 mass%, respectively, in terms of metal with respect to the total mass of the NO X purification catalyst. In addition, Table 1 shows the carrier type of the obtained NO X purification catalyst, the type of metal salt supported on the carrier, and the amount of metal species supported on the carrier.
（比較例１）
ケイタングステン酸を用いずに硝酸鉄のみを用いた以外は実施例１と同様にして、ＮＯＸ浄化用触媒を得た。得られたＮＯＸ浄化用触媒において、Ｆｅの担持量はＮＯＸ浄化用触媒の全質量に対して金属換算で３．１質量％であった。なお、得られたＮＯＸ浄化用触媒の担体種及び前記担体に担持させた金属塩の種類及び担体に担持させた金属種の担持量を表１に示す。
(Comparative Example 1)
Except using only iron nitrate without using silicotungstic acid in the same manner as in Example 1, to obtain a NO X purification catalyst. In the obtained NO X purification catalyst, the amount of Fe supported was 3.1% by mass in terms of metal with respect to the total mass of the NO X purification catalyst. In addition, Table 1 shows the carrier type of the obtained NO X purification catalyst, the type of metal salt supported on the carrier, and the amount of metal species supported on the carrier.
（比較例２）
ＣｅＯ２粉末に代えてＳｉＯ２粉末（比表面積３８０ｍ２／ｇ）を用いた以外は実施例１と同様にして、ＮＯＸ浄化用触媒を得た。得られたＮＯＸ浄化用触媒において、Ｗ及びＦｅの担持量はＮＯＸ浄化用触媒の全質量に対して金属換算でそれぞれ３４．４質量％及び１．７質量％であった。なお、得られたＮＯＸ浄化用触媒の担体種及び前記担体に担持させた金属塩の種類及び担体に担持させた金属種の担持量を表１に示す。
(Comparative Example 2)
A NO x purification catalyst was obtained in the same manner as in Example 1 except that SiO 2 powder (specific surface area of 380 m 2 / g) was used instead of CeO 2 powder. In the obtained NO X purification catalyst, the supported amounts of W and Fe were 34.4 mass% and 1.7 mass%, respectively, in terms of metal with respect to the total mass of the NO X purification catalyst. In addition, Table 1 shows the carrier type of the obtained NO X purification catalyst, the type of metal salt supported on the carrier, and the amount of metal species supported on the carrier.
（比較例３）
ＣｅＯ２粉末に代えてＳｉＯ２粉末（比表面積３８０ｍ２／ｇ）を用いた以外は実施例２と同様にして、ＮＯＸ浄化用触媒を得た。得られたＮＯＸ浄化用触媒において、Ｗ及びＦｅの担持量はＮＯＸ浄化用触媒の全質量に対して金属換算でそれぞれ３０．０質量％及び１．８質量％であった。なお、得られたＮＯＸ浄化用触媒の担体種及び前記担体に担持させた金属塩の種類及び担体に担持させた金属種の担持量を表１に示す。
(Comparative Example 3)
A NO X purification catalyst was obtained in the same manner as in Example 2 except that SiO 2 powder (specific surface area 380 m 2 / g) was used instead of CeO 2 powder. In the obtained NO X purification catalyst, the supported amounts of W and Fe were 30.0 mass% and 1.8 mass%, respectively, in terms of metal with respect to the total mass of the NO X purification catalyst. In addition, Table 1 shows the carrier type of the obtained NO X purification catalyst, the type of metal salt supported on the carrier, and the amount of metal species supported on the carrier.
（比較例４）
ＣｅＯ２粉末に代えてγ−Ａｌ２Ｏ３粉末（比表面積１５０ｍ２／ｇ）を用いた以外は実施例１と同様にして、ＮＯＸ浄化用触媒を得た。得られたＮＯＸ浄化用触媒において、Ｗ及びＦｅの担持量はＮＯＸ浄化用触媒の全質量に対して金属換算でそれぞれ３４．４質量％及び１．７質量％であった。なお、得られたＮＯＸ浄化用触媒の担体種及び前記担体に担持させた金属塩の種類及び担体に担持させた金属種の担持量を表１に示す。
(Comparative Example 4)
A NO X purification catalyst was obtained in the same manner as in Example 1 except that γ-Al 2 O 3 powder (specific surface area 150 m 2 / g) was used instead of CeO 2 powder. In the obtained NO X purification catalyst, the supported amounts of W and Fe were 34.4 mass% and 1.7 mass%, respectively, in terms of metal with respect to the total mass of the NO X purification catalyst. In addition, Table 1 shows the carrier type of the obtained NO X purification catalyst, the type of metal salt supported on the carrier, and the amount of metal species supported on the carrier.
（比較例５）
ＣｅＯ２粉末に代えてγ−Ａｌ２Ｏ３粉末（比表面積１５０ｍ２／ｇ）を用いた以外は実施例２と同様にして、ＮＯＸ浄化用触媒を得た。得られたＮＯＸ浄化用触媒において、Ｗ及びＦｅの担持量はＮＯＸ浄化用触媒の全質量に対して金属換算でそれぞれ３０．０質量％及び１．８質量％であった。なお、得られたＮＯＸ浄化用触媒の担体種及び前記担体に担持させた金属塩の種類及び担体に担持させた金属種の担持量を表１に示す。
(Comparative Example 5)
A NO X purification catalyst was obtained in the same manner as in Example 2 except that γ-Al 2 O 3 powder (specific surface area 150 m 2 / g) was used instead of CeO 2 powder. In the obtained NO X purification catalyst, the supported amounts of W and Fe were 30.0 mass% and 1.8 mass%, respectively, in terms of metal with respect to the total mass of the NO X purification catalyst. In addition, Table 1 shows the carrier type of the obtained NO X purification catalyst, the type of metal salt supported on the carrier, and the amount of metal species supported on the carrier.
（比較例６）
ＣｅＯ２粉末に代えてＺｒＯ２粉末（比表面積１２０ｍ２／ｇ）を用いた以外は実施例１と同様にして、ＮＯＸ浄化用触媒を得た。得られたＮＯＸ浄化用触媒において、Ｗ及びＦｅの担持量はＮＯＸ浄化用触媒の全質量に対して金属換算でそれぞれ３４．４質量％及び１．７質量％であった。なお、得られたＮＯＸ浄化用触媒の担体種及び前記担体に担持させた金属塩の種類及び担体に担持させた金属種の担持量を表１に示す。
(Comparative Example 6)
A NO x purification catalyst was obtained in the same manner as in Example 1 except that ZrO 2 powder (specific surface area 120 m 2 / g) was used instead of CeO 2 powder. In the obtained NO X purification catalyst, the supported amounts of W and Fe were 34.4 mass% and 1.7 mass%, respectively, in terms of metal with respect to the total mass of the NO X purification catalyst. In addition, Table 1 shows the carrier type of the obtained NO X purification catalyst, the type of metal salt supported on the carrier, and the amount of metal species supported on the carrier.
（比較例７）
ＣｅＯ２粉末に代えてＺｒＯ２粉末（比表面積１２０ｍ２／ｇ）を用いた以外は実施例２と同様にして、ＮＯＸ浄化用触媒を得た。得られたＮＯＸ浄化用触媒において、Ｗ及びＦｅの担持量はＮＯＸ浄化用触媒の全質量に対して金属換算でそれぞれ３０．０質量％及び１．８質量％であった。なお、得られたＮＯＸ浄化用触媒の担体種及び前記担体に担持させた金属塩の種類及び担体に担持させた金属種の担持量を表１に示す。
(Comparative Example 7)
A NO x purification catalyst was obtained in the same manner as in Example 2 except that ZrO 2 powder (specific surface area 120 m 2 / g) was used instead of CeO 2 powder. In the obtained NO X purification catalyst, the supported amounts of W and Fe were 30.0 mass% and 1.8 mass%, respectively, in terms of metal with respect to the total mass of the NO X purification catalyst. In addition, Table 1 shows the carrier type of the obtained NO X purification catalyst, the type of metal salt supported on the carrier, and the amount of metal species supported on the carrier.
（比較例８）
Ｓｉ／Ａｌ２比が４０であるＨ型ＺＳＭ‐５ゼオライト（比表面積２７０ｍ２／ｇ）を窒素流通下において６５０℃で７時間脱気処理した。脱気処理したＺＳＭ−５ゼオライトにＦｅＣｌ３粉末をＦｅ／Ａｌ比が１になるように窒素中で物理混合し、窒素流通下において６５０℃で２．５時間保持して、ＺＳＭ−５ゼオライトにＦｅを担持せしめた。その後、得られたＦｅ担持ＺＳＭ−５ゼオライトに対して洗浄、ろ過を３回繰り返し、１００℃で１２時間乾燥した後、大気中において６５０℃で５時間焼成した。焼成後のＦｅ担持ＺＳＭ−５ゼオライトを１０００ｋｇｆ／ｃｍ２で圧粉成型後、破砕、整粒して直径０．５〜１．０ｍｍのペレット化されたＮＯＸ浄化用触媒を得た。得られたＮＯＸ浄化用触媒において、Ｆｅの担持量はＮＯＸ浄化用触媒の全質量に対して金属換算で４．６質量％であった。なお、得られたＮＯＸ浄化用触媒の担体種及び前記担体に担持させた金属塩の種類及び担体に担持させた金属種の担持量を表１に示す。
(Comparative Example 8)
H-type ZSM-5 zeolite (specific surface area 270 m 2 / g) having a Si / Al 2 ratio of 40 was degassed at 650 ° C. for 7 hours under nitrogen flow. The degassed ZSM-5 zeolite is physically mixed with FeCl 3 powder so that the Fe / Al ratio is 1, and kept at 650 ° C. for 2.5 hours under a nitrogen flow to obtain ZSM-5 zeolite. Fe was supported. Thereafter, the obtained Fe-supported ZSM-5 zeolite was washed and filtered three times, dried at 100 ° C. for 12 hours, and then calcined at 650 ° C. for 5 hours in the air. The calcined Fe-supported ZSM-5 zeolite at 1000 kgf / cm 2 was crushed and sized to obtain a pelletized NO X purification catalyst having a diameter of 0.5 to 1.0 mm. In the obtained NO X purification catalyst, the amount of Fe supported was 4.6% by mass in terms of metal with respect to the total mass of the NO X purification catalyst. In addition, Table 1 shows the carrier type of the obtained NO X purification catalyst, the type of metal salt supported on the carrier, and the amount of metal species supported on the carrier.
［実施例１〜３及び比較例１〜８で得られたＮＯＸ浄化用触媒の特性の評価］
＜ＮＯＸ浄化活性の評価１＞
（i）評価方法
実施例１〜３及び比較例１〜８で得られたＮＯＸ浄化用触媒について、以下のようにして、それぞれＮＯＸ浄化率の測定を行い、各触媒のＮＯＸ浄化活性を評価した。すなわち、先ず、得られたＮＯＸ浄化用触媒０．２５ｇを触媒試料として常圧固定床流通型反応装置（大倉理研社製、ＴＰ−５０００）に設置した。次に、ＮＯ（０．１３容量％）、ＮＨ３（０．１３容量％）、Ｏ２（６．６７容量％）及びＨｅ（残部）からなるモデルガスを１５０ｍｌ／分のガス流量で供給し、触媒入りガス温度が２００℃となるように調整した。その後、触媒入りガス温度を２００℃に１５分間保持しつつ、定常状態における触媒入りガス及び触媒出ガス中のＮＯＸ濃度を測定し、それらの測定値からＮＯＸ浄化率を算出した。そして、触媒入りガス温度を５０℃ずつ上昇させて、２００℃から３００℃まで５０℃毎に上記と同様の方法で定常状態におけるＮＯＸ浄化率（単位：％）を算出した。
[Evaluation of characteristics of the NO X purification catalyst obtained in Examples 1 to 3 and Comparative Examples 1 to 8]
<Evaluation 1 of the NO X purification activity>
(I) Evaluation method For the NO X purification catalysts obtained in Examples 1 to 3 and Comparative Examples 1 to 8, the NO X purification rate is measured as follows, and the NO X purification activity of each catalyst is measured. Evaluated. Specifically, first, 0.25 g of the obtained NO X purification catalyst was set as a catalyst sample in an atmospheric pressure fixed bed flow type reactor (manufactured by Okura Riken Co., Ltd., TP-5000). Next, a model gas composed of NO (0.13% by volume), NH 3 (0.13% by volume), O 2 (6.67% by volume) and He (the balance) is supplied at a gas flow rate of 150 ml / min. The catalyst-containing gas temperature was adjusted to 200 ° C. Thereafter, while maintaining the temperature of the gas containing the catalyst at 200 ° C. for 15 minutes, the NO X concentration in the gas containing the catalyst and the gas emitted from the catalyst in the steady state was measured, and the NO X purification rate was calculated from these measured values. The catalyst-containing gas temperature was increased by 50 ° C., and the NO X purification rate (unit:%) in a steady state was calculated every 200 ° C. from 200 ° C. to 300 ° C. in the same manner as described above.
（ii）評価結果
実施例及び比較例で得られたＮＯＸ浄化用触媒のＮＯＸ浄化率（単位：％）について得られた結果を表２に示す。また、触媒入りガス温度２００℃及び２５０℃における各ＮＯＸ浄化用触媒のＮＯＸ浄化率を示すグラフをそれぞれ図２及び図３に示す。
(Ii) Evaluation results Examples and NO X purification rate of the NO X purification catalyst obtained in Comparative Example (unit:%) Table 2 shows the results obtained for. Further, a graph showing the NO X purification rate of each NO X purifying catalyst in the catalyst-containing gas temperature 200 ° C. and 250 ° C. in FIGS. 2 and 3, respectively.
表２及び図２、３に示した結果から明らかなように、本発明のＮＯＸ浄化用触媒（実施例１〜３）は、２５０℃以下という低温域においてもＮＯＸ浄化率が高く、ＮＯＸ浄化活性が優れたものであることが確認された。一方、セリア含有担体にタングステンやモリブデンを担持しなかった場合（比較例１）は、低温域におけるＮＯＸ浄化率が低いことが確認された。また、担体としてセリア以外のものを用いた場合（比較例２〜７）にも、低温域におけるＮＯＸ浄化率が低いことが確認された。なお、実施例２の結果を実施例１の結果と比較すると、鉄二置換型酸化物クラスターをセリア含有担体に担持するようにした場合（実施例２）は、低温域においてより優れたＮＯＸ浄化用触媒が得られることが確認された。 As apparent from the results shown in Table 2 and FIGS. 2 and 3, the NO X purification catalysts (Examples 1 to 3) of the present invention have a high NO X purification rate even in a low temperature range of 250 ° C. or less, and NO NO It was confirmed that the X purification activity was excellent. On the other hand, if no carrying tungsten or molybdenum ceria-containing support (Comparative Example 1), it was confirmed low NO X purification rate at low temperature range. Further, in the case of using something other than ceria as the carrier (comparative example 2-7), it was confirmed low NO X purification rate at low temperature range. Incidentally, when the results of Example 2 are compared with the results of Example 1, when the Tetsuji substituted oxide clusters so as to deposit ceria-containing support (Example 2) is more excellent NO X purification in the low temperature range It was confirmed that the catalyst for use was obtained.
（実施例４）
ＣｅＯ２粉末（比表面積１６０ｍ２／ｇ）を１０ｇ用い、前記ＣｅＯ２粉末１０ｇに対して鉄二置換型酸化物クラスターを２．５ｇ担持した以外は実施例２と同様にして、ＮＯＸ浄化用触媒を得た。得られたＮＯＸ浄化用触媒において、Ｗ及びＦｅの担持量はＮＯＸ浄化用触媒の全質量に対して金属換算でそれぞれ１１．７ｗｔ％及び０．７ｗｔ％であった。
Example 4
Using 10g of CeO 2 powder (specific surface area 160m 2 / g), except that the Tetsuji substituted oxide clusters to the CeO 2 powder 10g and 2.5g supported in the same manner as in Example 2, NO X purifying catalyst Got. In the obtained NO X purification catalyst, the supported amounts of W and Fe were 11.7 wt% and 0.7 wt% in terms of metal with respect to the total mass of the NO X purification catalyst, respectively.
（実施例５）
硝酸鉄（Ｆｅ（ＮＯ３）３ ９Ｈ２Ｏ）の代わりに硝酸マンガン（Ｍｎ（ＮＯ３）２ ６Ｈ２Ｏ）を用いてマンガン二置換型酸化物クラスター（［ＳｉＷ１０｛Ｍｎ（ＯＨ２）｝２Ｏ３８］６−）を調製し、ＣｅＯ２粉末（比表面積１６０ｍ２／ｇ）を１０ｇ用い、前記ＣｅＯ２粉末１０ｇに対して前記マンガン二置換型酸化物クラスターを２．５ｇ担持した以外は実施例２と同様にして、ＮＯＸ浄化用触媒を得た。得られたＮＯＸ浄化用触媒において、Ｗ及びＭｎの担持量はＮＯＸ浄化用触媒の全質量に対して金属換算でそれぞれ１１．１ｗｔ％及び０．７ｗｔ％であった。
(Example 5)
Using manganese nitrate (Mn (NO 3 ) 2 6H 2 O) instead of iron nitrate (Fe (NO 3 ) 3 9H 2 O), manganese disubstituted oxide clusters ([SiW 10 {Mn (OH 2 )}) 2 O 38 ] 6− ) was prepared, 10 g of CeO 2 powder (specific surface area 160 m 2 / g) was used, and 2.5 g of the manganese disubstituted oxide cluster was supported on 10 g of the CeO 2 powder. In the same manner as in Example 2, a NO X purification catalyst was obtained. In the obtained NO X purification catalyst, the supported amounts of W and Mn were 11.1 wt% and 0.7 wt% in terms of metal with respect to the total mass of the NO X purification catalyst, respectively.
（実施例６）
硝酸鉄（Ｆｅ（ＮＯ３）３ ９Ｈ２Ｏ）の代わりに硝酸銅（Ｃｕ（ＮＯ３）２ ３Ｈ２Ｏ）を用いて銅二置換型酸化物クラスター（［ＳｉＷ１０｛Ｃｕ（ＯＨ２）｝２Ｏ３８］６−）を調製し、ＣｅＯ２粉末（比表面積１６０ｍ２／ｇ）を１０ｇ用い、前記ＣｅＯ２粉末１０ｇに対して前記銅二置換型酸化物クラスターを２．５ｇ担持した以外は実施例２と同様にして、ＮＯＸ浄化用触媒を得た。得られたＮＯＸ浄化用触媒において、Ｗ及びＣｕの担持量はＮＯＸ浄化用触媒の全質量に対して金属換算でそれぞれ１１．０ｗｔ％及び０．８ｗｔ％であった。
(Example 6)
Copper disubstituted oxide clusters ([SiW 10 {Cu (OH 2 )}) using copper nitrate (Cu (NO 3 ) 2 3H 2 O) instead of iron nitrate (Fe (NO 3 ) 3 9H 2 O) 2 O 38 ] 6− ), 10 g of CeO 2 powder (specific surface area 160 m 2 / g) was used, and 2.5 g of the copper disubstituted oxide cluster was supported on 10 g of the CeO 2 powder. In the same manner as in Example 2, a NO X purification catalyst was obtained. In the obtained NO X purification catalyst, the supported amounts of W and Cu were 11.0 wt% and 0.8 wt% in terms of metal with respect to the total mass of the NO X purification catalyst, respectively.
（比較例９）
硝酸鉄（Ｆｅ（ＮＯ３）３ ９Ｈ２Ｏ）の代わりに硝酸銀（ＡｇＮＯ３）を用いて銀二置換型酸化物クラスター（［ＳｉＷ１０｛Ａｇ（ＯＨ２）｝２Ｏ３８］６−）を調製し、ＣｅＯ２粉末（比表面積１６０ｍ２／ｇ）を１０ｇ用い、前記ＣｅＯ２粉末１０ｇに対して銀二置換型酸化物クラスターを２．５ｇ担持したこと以外は実施例２と同様にして、ＮＯＸ浄化用触媒を得た。得られたＮＯＸ浄化用触媒において、Ｗ及びＡｇの担持量はＮＯＸ浄化用触媒の全質量に対して金属換算でそれぞれ１０．６ｗｔ％及び１．２ｗｔ％であった。
(Comparative Example 9)
A silver disubstituted oxide cluster ([SiW 10 {Ag (OH 2 )} 2 O 38 ] 6− ) was prepared using silver nitrate (AgNO 3 ) instead of iron nitrate (Fe (NO 3 ) 3 9H 2 O). NO X in the same manner as in Example 2 except that 10 g of CeO 2 powder (specific surface area 160 m 2 / g) was used and 2.5 g of silver disubstituted oxide clusters were supported on 10 g of CeO 2 powder. A purification catalyst was obtained. In the obtained NO X purification catalyst, the supported amounts of W and Ag were 10.6 wt% and 1.2 wt% in terms of metal with respect to the total mass of the NO X purification catalyst, respectively.
（比較例１０）
ＣｅＯ２粉末（比表面積１６０ｍ２／ｇ）を１０００ｋｇｆ／ｃｍ２で圧粉成型し、破砕、整粒して直径０．５〜１．０ｍｍのペレット化し、これをＮＯＸ浄化用触媒とした。
(Comparative Example 10)
CeO 2 powder (specific surface area 160 m 2 / g) was compacted at 1000 kgf / cm 2 , crushed and sized, and pelletized with a diameter of 0.5 to 1.0 mm, which was used as a NO X purification catalyst.
［実施例４〜６及び比較例９〜１０で得られたＮＯＸ浄化用触媒の特性の評価］
＜ＮＯＸ浄化活性の評価２＞
（i）評価方法
実施例４〜６及び比較例９〜１０で得られたＮＯＸ浄化用触媒について、以下のようにして、それぞれＮＯＸ浄化率の測定を行い、各触媒のＮＯＸ浄化活性を評価した。すなわち、先ず、得られたＮＯＸ浄化用触媒０．２５ｇを触媒試料として常圧固定床流通型反応装置（ベスト測器社製、ＣＡＴＡ−５０００）に設置した。次に、ＮＯ（５００ｐｐｍ）、ＮＨ３（５００ｐｐｍ）、Ｏ２（８容量％）、ＣＯ２（１０容量％）、Ｈ２Ｏ（８容量％）およびＮ２（残部）からなるモデルガスを１０Ｌ／分のガス流量で供給し、定常状態における触媒入りガス及び触媒出ガス中のＮＯＸ濃度を測定し、それらの測定値からＮＯＸ浄化率を算出した。なお、各触媒に対してＮＯＸ濃度の測定を７回行い、各回ごとに触媒入りガスの温度条件を変更した。また、各回の触媒入りガスの温度は、それぞれ２００℃、２２５℃、２５０℃、２７５℃、３００℃、３２５℃、３５０℃で一定とした。
[Evaluation of characteristics of the NO X purification catalyst obtained in Examples 4-6 and Comparative Example 9-10]
<Evaluation 2 of the NO X purification activity>
(I) Evaluation method For the NO X purification catalysts obtained in Examples 4 to 6 and Comparative Examples 9 to 10, the NO X purification rate is measured as follows, and the NO X purification activity of each catalyst is measured. Evaluated. That is, first, 0.25 g of the obtained NO X purification catalyst was set as a catalyst sample in an atmospheric pressure fixed bed flow type reaction apparatus (Best Instrument Co., Ltd., CATA-5000). Next, 10 L of model gas composed of NO (500 ppm), NH 3 (500 ppm), O 2 (8% by volume), CO 2 (10% by volume), H 2 O (8% by volume) and N 2 (remainder) is added. / min was supplied at a gas flow rate, the concentration of NO X catalyst containing gas and catalyst exiting gas at steady state was measured to calculate the NO X purification rate from the measured values. Incidentally, performed 7 times the measurement of the NO X concentration with respect to each catalyst, it was changed temperature condition of the catalyst entering gas each time. The temperature of the gas containing the catalyst at each time was constant at 200 ° C., 225 ° C., 250 ° C., 275 ° C., 300 ° C., 325 ° C., and 350 ° C., respectively.
（ii）評価結果
実施例４〜６及び比較例９〜１０で得られたＮＯＸ浄化用触媒のＮＯＸ浄化率と入りガス温度との関係を示すグラフを図４に示す。図４に示す結果からも明らかなように、Ｆｅ、Ｍｎ又はＣｕを用いて調製した二置換型酸化物クラスターをセリア担体に担持した本発明のＮＯｘ浄化用触媒（実施例４〜６）においては低温から十分に高いＮＯＸ浄化活性を示すことが確認された。これに対して、Ａｇを用いた比較のためのＮＯＸ浄化用触媒（比較例９）やセリア担体のみを用いた場合（比較例１０）ではＮＯＸ浄化活性が十分なもののとはならなかった。このような結果から、ＮＯｘ浄化用触媒においては、セリア担体に対して、タングステン及び／又はモリブデンと、Ｆｅ、Ｍｎ及びＣｕの中から選択される少なくとも１種とを組み合わせて用いることで低温域から十分に高度なＮＯｘ浄化活性が得られることが分かった。
(Ii) a graph showing the relationship between the evaluation results in Example 4-6 and the gas temperature entering the NO X purification rate of the NO X purification catalyst obtained in Comparative Example 9-10 in FIG. As is clear from the results shown in FIG. 4, in the NOx purification catalyst of the present invention (Examples 4 to 6) of the present invention in which a disubstituted oxide cluster prepared using Fe, Mn or Cu is supported on a ceria support. it was confirmed that shows a sufficiently high NO X purification activity from a low temperature. On the other hand, the NO X purification catalyst for comparison using Ag (Comparative Example 9) and the case where only the ceria carrier was used (Comparative Example 10) did not provide sufficient NO X purification activity. . From these results, in the NOx purification catalyst, a combination of tungsten and / or molybdenum and at least one selected from Fe, Mn and Cu is used for the ceria support from a low temperature range. It has been found that a sufficiently high NO x purification activity can be obtained.
以上説明したように、本発明によれば、低温域（例えば、２００〜２５０℃）においても十分なＮＯＸ浄化活性を有する窒素酸化物浄化用触媒、並びにその製造方法を提供することが可能となる。 As described above, according to the present invention, it is possible to provide a nitrogen oxide purification catalyst having sufficient NO x purification activity even in a low temperature range (for example, 200 to 250 ° C.) and a method for producing the same. Become.
したがって、本発明の窒素酸化物浄化用触媒は、希薄燃焼方式の内燃機関等から排出される排ガス中の窒素酸化物をアンモニア又はアンモニアへ加水分解可能な化合物により還元して浄化する窒素酸化物浄化用触媒として非常に有用である。 Therefore, the nitrogen oxide purification catalyst of the present invention is a nitrogen oxide purification catalyst that reduces and purifies nitrogen oxide in exhaust gas discharged from a lean combustion internal combustion engine or the like with ammonia or a compound that can be hydrolyzed to ammonia. It is very useful as a catalyst.
Claims (8)
セリアを主成分とするセリア含有担体と、前記担体に担持されているタングステン及びモリブデンからなる群から選択される少なくとも１種の第一金属元素と、前記担体に担持されている鉄、銅及びマンガンからなる群から選択される少なくとも１種の第二金属元素と、前記担体に担持されているケイ素とを備えることを特徴とする窒素酸化物浄化用触媒。 A catalyst for purifying nitrogen oxides, which reduces nitrogen oxides discharged from an internal combustion engine with ammonia or a compound that can be hydrolyzed to ammonia,
A ceria-containing support containing ceria as a main component, at least one first metal element selected from the group consisting of tungsten and molybdenum supported on the support, and iron, copper, and manganese supported on the support A nitrogen oxide purifying catalyst comprising: at least one second metal element selected from the group consisting of: and silicon supported on the carrier .
The oxide cluster is a disubstituted oxide cluster in which a metal atom in the oxide cluster of the first metal element is substituted with an atom of the second metal element. Of producing a catalyst for purifying nitrogen oxides.
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| JP5333598B2 (en) | 2009-10-20 | 2013-11-06 | トヨタ自動車株式会社 | Exhaust gas purification system for internal combustion engine |
| EP2611524B1 (en) | 2010-09-03 | 2014-04-30 | Danmarks Tekniske Universitet | HETEROPOLY ACID PROMOTED CATALYST FOR SCR OF NOx WITH AMMONIA |
| JP6273859B2 (en) * | 2014-01-27 | 2018-02-07 | 株式会社豊田中央研究所 | Three-way catalyst and exhaust gas purification method using the same |
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| JPH09225317A (en) * | 1996-02-26 | 1997-09-02 | Kemipuro Kasei Kk | Nickel / noble metal bimetallic cluster, catalyst comprising the same, and process for producing the same |
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