JPH11169670A - Nox occlusion-reduction type ternary catalyst and apparatus for cleaning exhaust gas using same - Google Patents
Nox occlusion-reduction type ternary catalyst and apparatus for cleaning exhaust gas using sameInfo
- Publication number
- JPH11169670A JPH11169670A JP10054138A JP5413898A JPH11169670A JP H11169670 A JPH11169670 A JP H11169670A JP 10054138 A JP10054138 A JP 10054138A JP 5413898 A JP5413898 A JP 5413898A JP H11169670 A JPH11169670 A JP H11169670A
- Authority
- JP
- Japan
- Prior art keywords
- air
- fuel ratio
- way catalyst
- nox
- catalyst
- 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.)
- Granted
Links
- 239000003054 catalyst Substances 0.000 title claims abstract description 172
- 238000004140 cleaning Methods 0.000 title 1
- 239000000843 powder Substances 0.000 claims abstract description 124
- 230000009467 reduction Effects 0.000 claims abstract description 64
- 229910052684 Cerium Inorganic materials 0.000 claims abstract description 22
- 229910052763 palladium Inorganic materials 0.000 claims abstract description 22
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 claims abstract description 16
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 claims abstract description 16
- 229910052746 lanthanum Inorganic materials 0.000 claims abstract description 15
- 229910052703 rhodium Inorganic materials 0.000 claims abstract description 14
- 229910000510 noble metal Inorganic materials 0.000 claims abstract description 13
- 229910052697 platinum Inorganic materials 0.000 claims abstract description 12
- 229910052751 metal Inorganic materials 0.000 claims abstract description 11
- 239000002184 metal Substances 0.000 claims abstract description 10
- 229910052700 potassium Inorganic materials 0.000 claims abstract description 10
- 229910052792 caesium Inorganic materials 0.000 claims abstract description 9
- 229910052749 magnesium Inorganic materials 0.000 claims abstract description 7
- 229910052712 strontium Inorganic materials 0.000 claims abstract description 7
- 229910052772 Samarium Inorganic materials 0.000 claims abstract description 6
- 229910052791 calcium Inorganic materials 0.000 claims abstract description 6
- 229910052742 iron Inorganic materials 0.000 claims abstract description 5
- 229910052759 nickel Inorganic materials 0.000 claims abstract description 5
- 229910052748 manganese Inorganic materials 0.000 claims abstract description 4
- 229910052796 boron Inorganic materials 0.000 claims abstract 2
- 239000000446 fuel Substances 0.000 claims description 195
- 238000003860 storage Methods 0.000 claims description 65
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims description 43
- 239000002131 composite material Substances 0.000 claims description 42
- 239000007789 gas Substances 0.000 claims description 40
- 239000000203 mixture Substances 0.000 claims description 25
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 22
- 238000002485 combustion reaction Methods 0.000 claims description 21
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 16
- 229910052760 oxygen Inorganic materials 0.000 claims description 16
- 239000001301 oxygen Substances 0.000 claims description 16
- 238000011144 upstream manufacturing Methods 0.000 claims description 15
- 239000010948 rhodium Substances 0.000 claims description 14
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 claims description 13
- 229910052779 Neodymium Inorganic materials 0.000 claims description 8
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 claims description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 6
- 238000001514 detection method Methods 0.000 claims description 4
- 150000004649 carbonic acid derivatives Chemical class 0.000 abstract description 3
- 150000002739 metals Chemical class 0.000 abstract description 2
- 229910052758 niobium Inorganic materials 0.000 abstract 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 46
- 239000002002 slurry Substances 0.000 description 30
- 239000007788 liquid Substances 0.000 description 20
- 238000000746 purification Methods 0.000 description 20
- 239000007864 aqueous solution Substances 0.000 description 19
- 229910052788 barium Inorganic materials 0.000 description 14
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 14
- 230000000052 comparative effect Effects 0.000 description 13
- 239000010410 layer Substances 0.000 description 13
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 description 12
- 238000000034 method Methods 0.000 description 12
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 description 11
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 11
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 10
- 238000010586 diagram Methods 0.000 description 10
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 description 9
- 229910052878 cordierite Inorganic materials 0.000 description 9
- JSKIRARMQDRGJZ-UHFFFAOYSA-N dimagnesium dioxido-bis[(1-oxido-3-oxo-2,4,6,8,9-pentaoxa-1,3-disila-5,7-dialuminabicyclo[3.3.1]nonan-7-yl)oxy]silane Chemical compound [Mg++].[Mg++].[O-][Si]([O-])(O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2)O[Al]1O[Al]2O[Si](=O)O[Si]([O-])(O1)O2 JSKIRARMQDRGJZ-UHFFFAOYSA-N 0.000 description 9
- 238000002347 injection Methods 0.000 description 9
- 239000007924 injection Substances 0.000 description 9
- 238000010521 absorption reaction Methods 0.000 description 8
- 238000006243 chemical reaction Methods 0.000 description 8
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 8
- 239000000243 solution Substances 0.000 description 7
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 6
- GPNDARIEYHPYAY-UHFFFAOYSA-N palladium(ii) nitrate Chemical compound [Pd+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O GPNDARIEYHPYAY-UHFFFAOYSA-N 0.000 description 6
- 239000011591 potassium Substances 0.000 description 6
- 238000012360 testing method Methods 0.000 description 6
- TVFDJXOCXUVLDH-UHFFFAOYSA-N caesium atom Chemical compound [Cs] TVFDJXOCXUVLDH-UHFFFAOYSA-N 0.000 description 5
- 229910017052 cobalt Inorganic materials 0.000 description 5
- 239000010941 cobalt Chemical group 0.000 description 5
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical group [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 description 5
- 238000003795 desorption Methods 0.000 description 5
- 230000006866 deterioration Effects 0.000 description 5
- 239000011777 magnesium Substances 0.000 description 5
- QEFYFXOXNSNQGX-UHFFFAOYSA-N neodymium atom Chemical compound [Nd] QEFYFXOXNSNQGX-UHFFFAOYSA-N 0.000 description 5
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 5
- QCWXUUIWCKQGHC-UHFFFAOYSA-N Zirconium Chemical compound [Zr] QCWXUUIWCKQGHC-UHFFFAOYSA-N 0.000 description 4
- IXSUHTFXKKBBJP-UHFFFAOYSA-L azanide;platinum(2+);dinitrite Chemical compound [NH2-].[NH2-].[Pt+2].[O-]N=O.[O-]N=O IXSUHTFXKKBBJP-UHFFFAOYSA-L 0.000 description 4
- AYJRCSIUFZENHW-UHFFFAOYSA-L barium carbonate Chemical compound [Ba+2].[O-]C([O-])=O AYJRCSIUFZENHW-UHFFFAOYSA-L 0.000 description 4
- 239000011575 calcium Substances 0.000 description 4
- 238000006073 displacement reaction Methods 0.000 description 4
- 239000011572 manganese Substances 0.000 description 4
- 238000004519 manufacturing process Methods 0.000 description 4
- VXNYVYJABGOSBX-UHFFFAOYSA-N rhodium(3+);trinitrate Chemical class [Rh+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O VXNYVYJABGOSBX-UHFFFAOYSA-N 0.000 description 4
- 150000003839 salts Chemical class 0.000 description 4
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 description 4
- 229910052726 zirconium Inorganic materials 0.000 description 4
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 3
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 description 3
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 3
- FYYHWMGAXLPEAU-UHFFFAOYSA-N Magnesium Chemical compound [Mg] FYYHWMGAXLPEAU-UHFFFAOYSA-N 0.000 description 3
- 230000009471 action Effects 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 3
- 239000002244 precipitate Substances 0.000 description 3
- 238000011946 reduction process Methods 0.000 description 3
- 238000005245 sintering Methods 0.000 description 3
- 239000011734 sodium Substances 0.000 description 3
- 229910052708 sodium Inorganic materials 0.000 description 3
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 2
- 229910017569 La2(CO3)3 Inorganic materials 0.000 description 2
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical group [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 description 2
- 229910002651 NO3 Inorganic materials 0.000 description 2
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 2
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 description 2
- 230000002378 acidificating effect Effects 0.000 description 2
- 238000013459 approach Methods 0.000 description 2
- ITHZDDVSAWDQPZ-UHFFFAOYSA-L barium acetate Chemical compound [Ba+2].CC([O-])=O.CC([O-])=O ITHZDDVSAWDQPZ-UHFFFAOYSA-L 0.000 description 2
- 239000002585 base Substances 0.000 description 2
- HSJPMRKMPBAUAU-UHFFFAOYSA-N cerium(3+);trinitrate Chemical compound [Ce+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O HSJPMRKMPBAUAU-UHFFFAOYSA-N 0.000 description 2
- 229910021446 cobalt carbonate Inorganic materials 0.000 description 2
- ZOTKGJBKKKVBJZ-UHFFFAOYSA-L cobalt(2+);carbonate Chemical compound [Co+2].[O-]C([O-])=O ZOTKGJBKKKVBJZ-UHFFFAOYSA-L 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000012535 impurity Substances 0.000 description 2
- NZPIUJUFIFZSPW-UHFFFAOYSA-H lanthanum carbonate Chemical compound [La+3].[La+3].[O-]C([O-])=O.[O-]C([O-])=O.[O-]C([O-])=O NZPIUJUFIFZSPW-UHFFFAOYSA-H 0.000 description 2
- 229960001633 lanthanum carbonate Drugs 0.000 description 2
- 229910017604 nitric acid Inorganic materials 0.000 description 2
- -1 or the like Chemical compound 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 238000011056 performance test Methods 0.000 description 2
- KZUNJOHGWZRPMI-UHFFFAOYSA-N samarium atom Chemical compound [Sm] KZUNJOHGWZRPMI-UHFFFAOYSA-N 0.000 description 2
- OERNJTNJEZOPIA-UHFFFAOYSA-N zirconium nitrate Chemical compound [Zr+4].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O OERNJTNJEZOPIA-UHFFFAOYSA-N 0.000 description 2
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- ATRRKUHOCOJYRX-UHFFFAOYSA-N Ammonium bicarbonate Chemical compound [NH4+].OC([O-])=O ATRRKUHOCOJYRX-UHFFFAOYSA-N 0.000 description 1
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonium chloride Substances [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 1
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 description 1
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 230000003213 activating effect Effects 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 1
- 150000001342 alkaline earth metals Chemical class 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- 239000001099 ammonium carbonate Substances 0.000 description 1
- 235000012501 ammonium carbonate Nutrition 0.000 description 1
- 235000011114 ammonium hydroxide Nutrition 0.000 description 1
- AYJRCSIUFZENHW-DEQYMQKBSA-L barium(2+);oxomethanediolate Chemical compound [Ba+2].[O-][14C]([O-])=O AYJRCSIUFZENHW-DEQYMQKBSA-L 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 229940052810 complex b Drugs 0.000 description 1
- 239000000470 constituent Substances 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 229910052735 hafnium Inorganic materials 0.000 description 1
- VBJZVLUMGGDVMO-UHFFFAOYSA-N hafnium atom Chemical compound [Hf] VBJZVLUMGGDVMO-UHFFFAOYSA-N 0.000 description 1
- 239000003779 heat-resistant material Substances 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 231100000572 poisoning Toxicity 0.000 description 1
- 230000000607 poisoning effect Effects 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 229910052761 rare earth metal Inorganic materials 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 239000011973 solid acid Substances 0.000 description 1
- 238000003746 solid phase reaction Methods 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- LEDMRZGFZIAGGB-UHFFFAOYSA-L strontium carbonate Chemical class [Sr+2].[O-]C([O-])=O LEDMRZGFZIAGGB-UHFFFAOYSA-L 0.000 description 1
- 229910052717 sulfur Inorganic materials 0.000 description 1
- 239000011593 sulfur Substances 0.000 description 1
- 238000010792 warming Methods 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Landscapes
- Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)
- Exhaust Gas Treatment By Means Of Catalyst (AREA)
- Catalysts (AREA)
- Exhaust Gas After Treatment (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、自動車（ガソリ
ン、ディーゼル）、ボイラーなどの内燃機関から排出さ
れる排気ガス中の炭化水素（以下、「ＨＣ」とい
う。）、一酸化炭素（以下、「ＣＯ」という。）及び窒
素酸化物（以下、「ＮＯｘ」という。）を浄化するＮＯ
ｘ吸蔵還元型三元触媒及びそれを使用した排気ガス浄化
装置に係り、更に詳細には、リーン雰囲気でのＮＯｘ浄
化率を向上させたＮＯｘ吸蔵還元型三元触媒及び排気ガ
ス通路にかかるＮＯｘ吸蔵還元型三元触媒を配置してＮ
Ｏｘ浄化率を向上させた排気ガス浄化装置に関するもの
である。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to hydrocarbons (hereinafter referred to as "HC") and carbon monoxide (hereinafter referred to as "HC") in exhaust gas discharged from internal combustion engines such as automobiles (gasoline and diesel) and boilers. NO, which purifies CO and nitrogen oxides (hereinafter referred to as "NOx").
More specifically, the present invention relates to a NOx storage-reduction type three-way catalyst and an exhaust gas purification device using the same, and more particularly to a NOx storage-reduction type three-way catalyst having an improved NOx purification rate in a lean atmosphere and NOx storage in an exhaust gas passage. Arrangement of reduced three-way catalyst and N
The present invention relates to an exhaust gas purification device with an improved Ox purification rate.
【０００２】[0002]
【従来の技術】近年、石油資源の枯渇問題や地球温暖化
問題から、低燃費自動車の要求が高まっており、ガソリ
ン自動車に対しては希薄燃焼自動車の開発が注目されて
いる。2. Description of the Related Art In recent years, the demand for fuel-efficient vehicles has been increasing due to the problem of depletion of petroleum resources and the problem of global warming, and the development of lean-burn vehicles has attracted attention for gasoline vehicles.
【０００３】かかる希薄燃焼自動車では、希薄燃焼走行
時において、排気空燃比が理論空燃比（以下、「ストイ
キ」という。）より酸素濃度の高い酸素過剰雰囲気（以
下、「リーン雰囲気」という。）となるが、リーン雰囲
気で通常の三元触媒を使用すると、ＮＯｘの浄化作用が
不十分となるため、リーン雰囲気になってもＮＯｘを浄
化できる触媒の開発が望まれていた。[0003] In such a lean-burn vehicle, during lean-burn operation, an exhaust air-fuel ratio is higher than a stoichiometric air-fuel ratio (hereinafter, referred to as "stoichiometric") in an oxygen-rich atmosphere (hereinafter, referred to as "lean atmosphere"). However, when a normal three-way catalyst is used in a lean atmosphere, the NOx purifying action becomes insufficient. Therefore, it has been desired to develop a catalyst that can purify NOx even in a lean atmosphere.
【０００４】このような要望に対して、例えば、白金と
ランタンを多孔質担体に担持した触媒（特開平５−１６
８８６０号公報）に代表されるように、リーン雰囲気で
排気ガス中のＮＯｘを吸着し、ストイキ又はそれより酸
素濃度が低い酸素欠乏雰囲気（以下、「リッチ雰囲気」
という。）で吸着したＮＯｘを還元処理する機能を持つ
ＮＯｘ吸蔵還元型三元触媒が提案されている。In response to such demands, for example, a catalyst in which platinum and lanthanum are supported on a porous carrier (Japanese Patent Laid-Open No.
No. 8860), NOx in the exhaust gas is adsorbed in a lean atmosphere, and a stoichiometric or oxygen-deficient atmosphere having a lower oxygen concentration (hereinafter referred to as a “rich atmosphere”).
That. )), There has been proposed a NOx occlusion reduction type three-way catalyst having a function of reducing the NOx adsorbed in (3).
【０００５】また、特開平７−１３９３９７号公報等に
は、かかるＮＯｘ吸蔵還元型三元触媒を排気系に設けた
機関が開示され、更に、特開平８−２７０４４０号公報
等には、ＮＯｘ吸蔵還元型三元触媒の上流側及び下流側
に三元触媒をそれぞれ配置した排気ガス浄化装置が開示
されている。Japanese Patent Application Laid-Open No. 7-139297 discloses an engine provided with such a NOx storage-reduction type three-way catalyst in an exhaust system. Further, Japanese Patent Application Laid-Open No. 8-270440 discloses an NOx storage device. There is disclosed an exhaust gas purifying apparatus in which three-way catalysts are arranged upstream and downstream of a reduction type three-way catalyst, respectively.
【０００６】[0006]
【発明が解決しようとする課題】しかしながら、従来の
ＮＯｘ吸蔵還元型三元触媒を用いても、なおＮＯｘの浄
化性能が不十分となることがあるという課題があった。
また、リーン域でＮＯｘ吸蔵還元型三元触媒に吸着され
たＮＯｘが、燃焼混合気の空燃比がストイキ又はリッチ
に切り換わることにより放出され、還元される際には、
ＨＣ及びＣＯが必要となるが、排気系において、ＮＯｘ
吸蔵還元型三元触媒より上流側に通常の三元触媒を配置
すると、この三元触媒の酸化反応によってＨＣ及びＣＯ
が消費されてしまうため、ＮＯｘの還元処理に必要とな
るＨＣ及びＣＯがＮＯｘ吸蔵還元型三元触媒に十分供給
されなくなるという課題があった。However, even if a conventional NOx storage reduction type three-way catalyst is used, there is a problem that the NOx purification performance may still be insufficient.
Further, when NOx adsorbed by the NOx storage reduction type three-way catalyst in the lean region is released by the air-fuel ratio of the combustion air-fuel mixture being switched to stoichiometric or rich, and is reduced,
Although HC and CO are required, NOx
When a normal three-way catalyst is arranged upstream of the storage reduction type three-way catalyst, HC and CO are oxidized by the three-way catalyst.
Is consumed, so that there is a problem that HC and CO required for the NOx reduction process are not sufficiently supplied to the NOx storage reduction type three-way catalyst.
【０００７】このような状況において、ＮＯｘ吸蔵還元
型三元触媒から放出されるＮＯｘを還元処理するのに必
要なＨＣ及びＣＯを供給するためには、リッチ度合いを
高める手法が採られるが、ＮＯｘ吸蔵還元型三元触媒で
は、排気ガス温度や劣化状態によってＮＯｘを吸収し又
は放出する能力が変化するため、必要以上に酸素リッチ
度合いを高めてしまうことがあり、逆にＨＣ及びＣＯの
浄化性能が悪化するという課題もあった。In such a situation, in order to supply HC and CO necessary for reducing the NOx released from the NOx storage reduction type three-way catalyst, a method of increasing the degree of richness is employed. In the storage reduction type three-way catalyst, since the ability to absorb or release NOx changes depending on the exhaust gas temperature and the state of deterioration, the degree of oxygen richness may be increased more than necessary. There was also a problem that it became worse.
【０００８】本発明は、このような技術の有する課題に
鑑みてなされたものであり、その目的とするところは、
リーン雰囲気において、ＮＯｘの浄化性能に優れるＮＯ
ｘ吸蔵還元型三元触媒を提供することにあり、また、排
気空燃比がリーン域からストイキ又はリッチ域に切り換
わった際にもＮＯｘ浄化率を向上でき、且つリッチ域に
おいてＨＣ及びＣＯの浄化性能の悪化を最小限に抑制で
きる排気ガス浄化装置を提供することにある。[0008] The present invention has been made in view of the problems of such technology, and has as its object the following:
NO with excellent NOx purification performance in lean atmosphere
x-reduction type three-way catalyst, and can improve the NOx purification rate even when the exhaust air-fuel ratio switches from a lean region to a stoichiometric or rich region, and purifies HC and CO in a rich region. An object of the present invention is to provide an exhaust gas purifying apparatus capable of minimizing deterioration of performance.
【０００９】[0009]
【課題を解決するための手段】本発明者らは、上記課題
を解決すべく鋭意研究した結果、所定の複合酸化物と貴
金属元素とを適切に共存させることなどにより、ＮＯｘ
吸蔵還元型三元触媒のＮＯｘ浄化性能が向上すること、
ＮＯｘ吸蔵還元型三元触媒より排気系上流側に配置した
三元触媒中の酸素ストレージ能力に寄与する成分量を低
減することなどにより、ＮＯｘを還元処理するために必
要となるＨＣ及びＣＯがＮＯｘ吸蔵還元型三元触媒に十
分供給されること、及び排気空燃比に基づいて燃焼混合
気の空燃比を目標空燃比にフィードバック制御する空燃
比フィードバック手段を設けることなどにより、ＮＯｘ
吸蔵還元型三元触媒のＨＣ及びＣＯの浄化性能の悪化を
最小限に抑えられることを見出し、本発明を完成するに
至った。Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, by appropriately coexisting a predetermined composite oxide and a noble metal element, NOx has been developed.
The NOx purification performance of the storage reduction three-way catalyst is improved,
HC and CO required for the reduction treatment of NOx are reduced by reducing the amount of components contributing to the oxygen storage capacity in the three-way catalyst disposed on the exhaust system upstream side from the NOx storage reduction type three-way catalyst. NOx is provided by sufficient supply to the storage reduction three-way catalyst and by providing air-fuel ratio feedback means for feedback-controlling the air-fuel ratio of the combustion mixture to the target air-fuel ratio based on the exhaust air-fuel ratio.
It has been found that deterioration of the purification performance of the storage reduction three-way catalyst for HC and CO can be minimized, and the present invention has been completed.
【００１０】即ち、本発明のＮＯｘ吸蔵還元型三元触媒
は、リーン雰囲気で排気ガス中のＮＯｘを吸収し、吸収
したＮＯｘを理論空燃比又はリッチ雰囲気で放出して還
元処理するＮＯｘ吸蔵還元型三元触媒において、白金、
パラジウム、ロジウムから成る群より選ばれた少なくと
も１種の貴金属を多孔質担体に担持した貴金属担持粉末
と、次式 ＬｎαＢＯβ・・・ （式中のＬｎは、Ｌａ、Ｃｅ、Ｎｄ及びＳｍから成る群
より選ばれた少なくとも１種、Ｂは、Ｆｅ、Ｃｏ、Ｎｉ
及びＭｎから成る群より選ばれた少なくとも１種を示
し、０＜α＜１、０＜β＜４である。）で表される複合
酸化物粉末と、Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ｎａ、Ｋ及び
Ｃｓから成る群より選ばれた少なくとも１種の金属の炭
酸塩と、を含有することを特徴とする。That is, the NOx storage reduction type three-way catalyst of the present invention absorbs NOx in exhaust gas in a lean atmosphere and releases the absorbed NOx in a stoichiometric air-fuel ratio or a rich atmosphere to perform a reduction treatment. In a three-way catalyst, platinum,
A noble metal-supporting powder in which at least one noble metal selected from the group consisting of palladium and rhodium is supported on a porous carrier, and the following formula: LnαBOβ (where Ln is a group consisting of La, Ce, Nd and Sm) At least one selected from the group consisting of Fe, Co, Ni
And Mn, wherein 0 <α <1 and 0 <β <4. ), And a carbonate of at least one metal selected from the group consisting of Mg, Ca, Sr, Ba, Na, K, and Cs.
【００１１】また、本発明の排気ガス浄化装置は、ＮＯ
ｘ吸蔵還元型三元触媒を利用したものであり、排気系の
上流側から、三元触媒とＮＯｘ吸蔵還元型三元触媒とを
順次配置した排気ガス浄化装置において、上記三元触媒
が、白金、パラジウム、ロジウムから成る群より選ばれ
た少なくとも１種を含有し、且つこの三元触媒に含まれ
るセリア及びセリアを含む複合酸化物の量が触媒１リッ
トル当たり５〜３０ｇであり、上記ＮＯｘ吸蔵還元型三
元触媒が、上述したＮＯｘ吸蔵還元型三元触媒であるこ
とを特徴とする。Further, the exhaust gas purifying apparatus of the present invention has a NO.
In the exhaust gas purifying apparatus, which utilizes a three-way catalyst of an x-storage reduction type, and in which a three-way catalyst and a NOx storage-reduction type three-way catalyst are sequentially arranged from the upstream side of the exhaust system, the three-way catalyst is platinum. , Palladium, rhodium and at least one selected from the group consisting of ceria and the ceria-containing composite oxide contained in the three-way catalyst in an amount of 5 to 30 g per liter of the catalyst; The reduction three-way catalyst is the NOx storage reduction three-way catalyst described above.
【００１２】更に、本発明の排気ガス浄化装置の好適形
態は、上記ＮＯｘ吸蔵還元型三元触媒より上流側に配置
されて排気空燃比を検出する第１空燃比検出手段と、該
ＮＯｘ吸蔵還元型三元触媒より下流側に配置されて排気
空燃比を検出する第２空燃比検出手段とを備え、更に、
通常状態において、上記第１空燃比検出手段で検出され
る排気空燃比に基づき燃焼混合気の空燃比を目標空燃比
にフィードバック制御する第１空燃比フィードバック手
段と、燃焼混合気の目標空燃比がリーンから理論空燃比
又はリッチに切り換えられた直後において、上記第２空
燃比検出手段で検出される排気空燃比に基づき燃焼混合
気の空燃比を目標空燃比にフィードバック制御する第２
空燃比フィードバック手段とを付加して成ることを特徴
とする。Further, a preferred embodiment of the exhaust gas purifying apparatus of the present invention is a first air-fuel ratio detecting means disposed upstream of the NOx storage reduction type three-way catalyst for detecting an exhaust air-fuel ratio; A second air-fuel ratio detecting unit that is disposed downstream of the three-way catalyst and detects an exhaust air-fuel ratio.
In a normal state, the first air-fuel ratio feedback means for feedback-controlling the air-fuel ratio of the combustion mixture to the target air-fuel ratio based on the exhaust air-fuel ratio detected by the first air-fuel ratio detection means, and the target air-fuel ratio of the combustion mixture Immediately after switching from lean to the stoichiometric air-fuel ratio or rich, the second air-fuel ratio of the combustion mixture is feedback-controlled to the target air-fuel ratio based on the exhaust air-fuel ratio detected by the second air-fuel ratio detecting means.
It is characterized by adding air-fuel ratio feedback means.
【００１３】[0013]
【作用】本発明のＮＯｘ吸蔵還元型三元触媒は、リーン
雰囲気でＮＯｘを吸収し、ストイキ又はリッチ雰囲気で
吸着したＮＯｘを放出して浄化する。The NOx storage reduction type three-way catalyst of the present invention absorbs NOx in a lean atmosphere and releases and adsorbs NOx in a stoichiometric or rich atmosphere.
【００１４】リーン雰囲気において、ＮＯｘは貴金属を
多孔質担体に担持した貴金属担持粉末及び複合酸化物粉
末によって活性化された後、マグネシウム、カルシウ
ム、ストロンチウム、バリウム、ナトリウム、カリウム
及びセシウム等の炭酸塩に吸着される。ここで、貴金属
担持粉末及び複合酸化物は粉末状で共存しているので、
排気ガスの流れがスムーズになり、高い活性が得られ
る。In a lean atmosphere, NOx is activated by a noble metal-supporting powder in which a noble metal is supported on a porous carrier and a composite oxide powder, and then converted into carbonates such as magnesium, calcium, strontium, barium, sodium, potassium and cesium. Adsorbed. Here, since the noble metal-supported powder and the composite oxide coexist in a powder form,
Exhaust gas flow is smooth and high activity is obtained.
【００１５】ストイキ又はリッチ雰囲気において、ＨＣ
は、固体酸としての機能により複合酸化物の成分Ｂに係
る複合体（以下、「複合体Ｂ」という。）に強力に吸着
され、その近傍に存在する複合酸化物の成分Ａ（又は
式では、Ｌｎ等に該当）に係る複合体（以下、「複合
体Ａ」という。）に吸着されたＮＯｘと反応する。これ
により、ＮＯｘ吸蔵還元型三元触媒に吸着されたＮＯｘ
は、ＮＯｘ吸蔵還元型三元触媒から脱着し、その後還元
処理がなされる。In a stoichiometric or rich atmosphere, HC
Is strongly adsorbed on the complex relating to the component B of the composite oxide (hereinafter, referred to as “composite B”) due to its function as a solid acid, and the component A of the composite oxide (or the formula , Ln, etc. (hereinafter, referred to as “composite A”). As a result, the NOx adsorbed by the NOx storage reduction type three-way catalyst
Is desorbed from the NOx storage reduction type three-way catalyst, and then a reduction process is performed.
【００１６】本発明のＮＯｘ吸蔵還元型三元触媒のＮＯ
ｘ浄化性能が、熱耐久後においても高いのは、貴金属を
多孔質担体に担持した貴金属担持粉末及び複合酸化物が
粉末状で存在すること並びに複合酸化物が、上記又は
式中、α（以下、「Ａサイト割合」という。）の少な
いペロブスカイト型構造を基本としており、複合体Ａ及
び複合体Ｂや触媒中の他の成分（例えば、アルミナ）と
の固相反応が回避されたためと推察される。The NO of the NOx storage reduction type three-way catalyst of the present invention
x The purification performance is high even after the heat endurance because the noble metal-supported powder in which the noble metal is supported on the porous carrier and the composite oxide are present in the form of powder, and the composite oxide is represented by α or , "A site ratio"), which is presumed to be due to the fact that the solid-phase reaction with the complex A and the complex B and other components (for example, alumina) in the catalyst was avoided. You.
【００１７】本発明の内燃機関の排気ガス浄化装置にお
いては、排気空燃比がリーン雰囲気からストイキ又はリ
ッチ雰囲気に切り換わった際、ＮＯｘ吸蔵還元型三元触
媒に吸着したＮＯｘは脱着し、その後還元処理がなされ
るが、ＮＯｘ吸蔵還元型三元触媒より排気系上流側に配
置された三元触媒中の酸素ストレージ能力に寄与する成
分量が低減されているため、三元触媒の酸化反応によっ
て消費されるＨＣ及びＣＯの量が減少し、還元処理に必
要なＨＣ及びＣＯがＮＯｘ吸蔵還元型三元触媒に十分供
給されることから、ＮＯｘの浄化率が向上する。In the exhaust gas purifying apparatus for an internal combustion engine according to the present invention, when the exhaust air-fuel ratio is switched from a lean atmosphere to a stoichiometric or rich atmosphere, NOx adsorbed on the NOx storage-reduction type three-way catalyst is desorbed and then reduced. Although the processing is performed, the amount of components contributing to the oxygen storage capacity in the three-way catalyst disposed upstream of the NOx storage reduction type three-way catalyst in the exhaust system is reduced, so that the three-way catalyst is consumed by the oxidation reaction of the three-way catalyst. Since the amounts of HC and CO to be reduced decrease and HC and CO required for the reduction treatment are sufficiently supplied to the NOx storage reduction type three-way catalyst, the purification rate of NOx is improved.
【００１８】また、ＮＯｘ吸蔵還元型三元触媒より排気
系上流側及び下流側に設置した空燃比検出手段の出力信
号を用いて、排気空燃比がリーン域からリッチ域に切り
換わった際において、リッチに保持する時間を制御する
と、ＮＯｘ吸蔵還元型三元触媒の劣化状態や作動温度に
依存することなく、リーン域で吸着したＮＯｘが十分に
放出されて還元処理されるため、ＮＯｘの浄化率が向上
するだけでなく、必要以上のＨＣ及びＣＯを供給しなく
てもよく、リッチ域におけるＨＣ及びＣＯの浄化性能の
悪化が最小限に抑えられる。Further, when the exhaust air-fuel ratio is switched from a lean region to a rich region by using output signals of air-fuel ratio detecting means provided upstream and downstream of the exhaust system from the NOx storage reduction type three-way catalyst, By controlling the time for which the NOx is kept rich, the NOx adsorbed in the lean region is sufficiently released and reduced without depending on the deterioration state and the operating temperature of the NOx storage reduction type three-way catalyst. Not only does not need to be supplied, but also the deterioration of HC and CO purification performance in the rich region is minimized.
【００１９】[0019]
【発明の実施の形態】以下、本発明を詳細に説明する。
まず、本発明のＮＯｘ吸蔵還元型三元触媒につき説明す
る。本発明のＮＯｘ吸蔵還元型三元触媒は、貴金属担持
粉末と、複合酸化物粉末と炭酸塩とを含有する。DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.
First, the NOx storage reduction type three-way catalyst of the present invention will be described. The NOx storage reduction three-way catalyst of the present invention contains a noble metal-supported powder, a composite oxide powder, and a carbonate.
【００２０】ここで、貴金属担持粉末は、貴金属を多孔
質担体に担持したものであり、多孔質担体の代表例とし
ては、アルミナを挙げることができる。多孔質担体とし
ては、耐熱性の高いものが好ましく、比表面積が５０〜
３００ｃｍ2／ｇ程度の活性アルミナを最も好適に使用
できる。Here, the noble metal-supported powder is obtained by supporting a noble metal on a porous carrier, and a typical example of the porous carrier is alumina. As the porous carrier, those having high heat resistance are preferable, and the specific surface area is 50 to
Activated alumina of about 300 cm 2 / g can be most preferably used.
【００２１】また、貴金属は、特にストイキにおける三
元触媒の機能を確保するために担持するものであり、具
体的には、白金、パラジウム又はロジウム及びこれらの
任意の組み合わせを挙げることができるが、パラジウム
又はロジウム及びパラジウムとロジウムの組み合わせが
好ましく、パラジウムが最も好ましい。なお、かかる貴
金属は、少なくとも一部が多孔質担体に担持されていれ
ばよい。The noble metal is carried to secure the function of the three-way catalyst particularly in the stoichiometric catalyst. Specific examples include platinum, palladium or rhodium and any combination thereof. Palladium or rhodium and a combination of palladium and rhodium are preferred, with palladium being most preferred. It is sufficient that at least a part of the noble metal is supported on the porous carrier.
【００２２】上述した複合酸化物粉末は、次式 ＬｎαＢＯβ・・・ により表される。ここで、式中、Ｌｎは、ランタン、
セリウム、ネオジウム又はサマリウム及びこれらの任意
の組み合わせを示し、Ｂは、鉄、コバルト、ニッケル又
はマンガン及びこれらの任意の組み合わせを示す。Ｌｎ
としては、ランタン、ネオジウムが好ましく、Ｂは、コ
バルト、マンガンが好ましい。Ａサイト割合は、０＜α
＜１の範囲がよく、０．８＜α＜０．９が好ましい。な
お、式において、０＜α＜１、０＜β＜４の範囲を逸
脱すると、ＮＯｘ活性化能が低下するため、好ましくな
い。The above-described composite oxide powder is represented by the following formula: LnαBOβ... Where Ln is a lantern,
C represents cerium, neodymium or samarium and any combination thereof, and B represents iron, cobalt, nickel or manganese and any combination thereof. Ln
Are preferably lanthanum and neodymium, and B is preferably cobalt and manganese. A site ratio is 0 <α
<1 is preferable, and 0.8 <α <0.9 is preferable. In addition, in the formula, when the value deviates from the range of 0 <α <1, 0 <β <4, the NOx activating ability decreases, which is not preferable.
【００２３】また、この複合酸化物粉末の好適例は、次
式 （Ｌｎ1-δＣδ）αＢＯβ・・・ により表される。ここで、式中、Ｌｎ及びＢは、上記
と同じものを示し、Ｃは、バリウム又はカリウム、バリ
ウムとカリウムとの組み合わせを示す。Ｌｎとしては、
ランタン若しくはネオジウム又はランタンとネオジウム
との組み合わせが好ましく、ランタンが最も好ましい。
Ｂとしては、コバルトが好ましい。δは、０＜δ＜１の
範囲がよく、δが０＜δ＜１の範囲を逸脱すると、酸化
物の構造安定性が悪化し、好ましくない。αは、０．８
＜α＜１の範囲がよく、０．８＜α＜０．９が好まし
い。αが０．８より小さいと、結晶構造が不安定にな
り、αが０．９より大きくなり、１に近づくと、アルミ
ナ等と反応しやすくなり、結晶構造を保てなくなること
があるから、好ましくない。なお、βは、各元素の原子
価を満足する酸素量である。A preferred example of the composite oxide powder is represented by the following formula (Ln 1 -δCδ) αBOβ. Here, in the formula, Ln and B represent the same as described above, and C represents barium or potassium, or a combination of barium and potassium. As Ln,
Lanthanum or neodymium or a combination of lanthanum and neodymium is preferred, with lanthanum being most preferred.
B is preferably cobalt. δ is preferably in the range of 0 <δ <1, and when δ is out of the range of 0 <δ <1, the structural stability of the oxide is deteriorated, which is not preferable. α is 0.8
<Α <1 is preferable, and 0.8 <α <0.9 is preferable. If α is smaller than 0.8, the crystal structure becomes unstable, α becomes larger than 0.9, and when it approaches 1, it becomes easy to react with alumina or the like, and the crystal structure may not be maintained. Not preferred. Here, β is the amount of oxygen that satisfies the valence of each element.
【００２４】又はの複合酸化物は、各成分の全てが
複合化していることが好ましいが、その一部が複合化し
ている場合でも目的とする作用は得られる。また又は
の複合酸化物中には、構成元素に含まれる不純物が混
入することがあるが、その作用を妨げる量でなければ問
題は生じない。例えば、複合酸化物を構成する元素のう
ち、バリウム中にストロンチウムが微量含まれたり、ラ
ンタン中にセリウム、ネオジウム、サマリウムなどが微
量含まれていたり、ジルコニウム中にハフニウムやイオ
ウが微量含まれていても差し支えない。It is preferable that all of the components of the composite oxide be composited, but the desired action can be obtained even when a part of the components is composited. In some cases, impurities contained in the constituent elements may be mixed into the composite oxide. However, no problem occurs unless the amount of the impurities impairs the action. For example, among the elements constituting the composite oxide, barium contains a small amount of strontium, lanthanum contains a small amount of cerium, neodymium, samarium, or the like, or zirconium contains a small amount of hafnium or sulfur. No problem.
【００２５】上述した炭酸塩としては、マグネシウム、
カルシウム、ストロンチウム、バリウム、ナトリウム、
カリウム又はセシウム及びこれらの任意の混合物に係る
炭酸塩であればよく、バリウム、ストロンチウムの炭酸
塩が好ましい。なお、後述するＮＯｘ吸蔵還元型三元触
媒に係る複合酸化物の製造方法に関連するが、マグネシ
ウム、カルシウム、ストロンチウム、バリウム、ナトリ
ウム、カリウム又はセシウム及びこれらの混合物の金属
塩水溶液における塩の種類は、特に限定されるものでは
なく、硝酸塩、酢酸塩、炭酸塩、水酸化塩、塩酸塩など
が挙げられる。また、１種から成る水溶液でも、あるい
は２種以上の金属を混合した水溶液であっても差し支え
ない。The above-mentioned carbonates include magnesium,
Calcium, strontium, barium, sodium,
Any carbonate may be used for potassium or cesium and any mixture thereof, and barium and strontium carbonates are preferred. In addition, although it relates to the method for producing a composite oxide according to the NOx storage reduction type three-way catalyst described below, magnesium, calcium, strontium, barium, sodium, potassium or cesium and the kind of salt in a metal salt aqueous solution of a mixture thereof are as follows: The salt is not particularly limited, and examples thereof include a nitrate, an acetate, a carbonate, a hydroxide, and a hydrochloride. Further, an aqueous solution of one kind or an aqueous solution in which two or more kinds of metals are mixed may be used.
【００２６】また、ＮＯｘ吸蔵還元型三元触媒において
は、貴金属担持粉末と複合酸化物の含有量を触媒１Ｌ当
たり２００〜３００ｇとすることが好ましい。このよう
な含有量とすることにより、貴金属担持粉末及び複合酸
化物の分散性を向上でき、排気ガスの複合体Ｂ及び複合
体Ａへの拡散性を高めることができるので、より多量の
ＮＯｘ浄化が可能になると考えられる。In the NOx storage reduction type three-way catalyst, the content of the noble metal-supported powder and the composite oxide is preferably 200 to 300 g per liter of the catalyst. With such a content, the dispersibility of the noble metal-supported powder and the composite oxide can be improved, and the diffusivity of the exhaust gas into the composite B and the composite A can be increased. Is thought to be possible.
【００２７】上述の如く、本発明のＮＯｘ吸蔵還元型三
元触媒は、貴金属担持粉末、複合酸化物粉末及び炭酸塩
を必須成分とするが、これ以外に他の成分を添加するこ
とも可能である。例えば、アルミナの耐熱性を向上させ
る目的で、従来から三元触媒で使用されているように、
セリウム、ランタン等の希土類化合物やジルコニウムな
どの添加物を加えてもよい。また、三元触媒としての機
能を増強するため、従来から三元触媒に用いられている
材料を添加してもよく、例えば、酸素ストレージ機能を
持つセリア、貴金属へのＨＣ吸着被毒を緩和するバリウ
ム、ロジウムの耐熱性向上に寄与するジルコニア等を加
えてもよい。As described above, the NOx occlusion reduction type three-way catalyst of the present invention contains the noble metal-supported powder, the composite oxide powder and the carbonate as essential components, but other components can be added. is there. For example, in order to improve the heat resistance of alumina, as conventionally used in three-way catalysts,
Rare earth compounds such as cerium and lanthanum and additives such as zirconium may be added. Further, in order to enhance the function as a three-way catalyst, a material conventionally used in a three-way catalyst may be added. For example, ceria having an oxygen storage function and HC adsorption poisoning to a noble metal are reduced. Zirconia or the like that contributes to improving the heat resistance of barium or rhodium may be added.
【００２８】上述した本発明のＮＯｘ吸蔵還元型三元触
媒は、無担体でも使用することができるが、自動車の排
ガスを浄化するに当たっては、一体構造型担体に担持し
て用いるのが好ましい。一体構造型担体としては、耐熱
性材料から成るモノリス担体が好ましく、例えば、コー
ディエライトなどのセラミックスやフェライト系ステン
レスなどの金属製のものを好適に使用することができ
る。The NOx storage-reduction type three-way catalyst of the present invention described above can be used without a carrier. However, in purifying exhaust gas from automobiles, it is preferable to use the NOx storage-reduction type three-way catalyst supported on a monolithic carrier. As the monolithic carrier, a monolith carrier made of a heat-resistant material is preferable. For example, a ceramic carrier such as cordierite or a metal carrier such as ferrite stainless steel can be suitably used.
【００２９】本発明のＮＯｘ吸蔵還元型三元触媒に係る
複合酸化物の製造方法には、例えば、各成分の金属塩
（硝酸塩、炭酸塩、クエン酸、塩酸塩など）の水溶液を
調製し、場合によってはこれに沈澱剤（アンモニア、炭
酸アンモニウムなど）を添加して沈澱物を生成させ、こ
れら溶液又は沈澱物を乾燥、焼成して複合酸化物粉末を
得る方法があり、これらの製法により各成分の少なくと
も一部が複合化し、目的に合致したものとなる。但し、
上記複合酸化物の製造方法は、上記方法に必ずしも限定
されるものではなく、上記以外の方法であっても、意図
する複合酸化物が形成されれば十分である。In the method for producing a composite oxide according to the NOx storage-reduction type three-way catalyst of the present invention, for example, an aqueous solution of a metal salt (nitrate, carbonate, citric acid, hydrochloride, etc.) of each component is prepared, In some cases, a precipitation agent (ammonia, ammonium carbonate, etc.) is added to the mixture to form a precipitate, and a solution or precipitate is dried and calcined to obtain a composite oxide powder. At least a part of the components is compounded to meet the purpose. However,
The method for producing the above-mentioned composite oxide is not necessarily limited to the above-mentioned method, and any method other than the above is sufficient if the intended composite oxide is formed.
【００３０】上述した本発明のＮＯｘ吸蔵還元型三元触
媒は、空燃比が１０〜５０の範囲で繰り返し変動するリ
ーンバーンエンジン車の排ガスを浄化するのに好適であ
り、このような環境下で使用すると、リーン雰囲気でＮ
Ｏｘを吸着し、ストイキ又はリッチ雰囲気で、吸着した
ＮＯｘを還元処理して脱着するため、高いＮＯｘ浄化性
能が得られる。更に好適な範囲は、リーン雰囲気が１５
〜５０で、ストイキ又はリッチ雰囲気が１０〜１４．８
である。The NOx storage-reduction type three-way catalyst of the present invention described above is suitable for purifying exhaust gas of a lean burn engine vehicle whose air-fuel ratio repeatedly fluctuates in the range of 10 to 50. When used, N in a lean atmosphere
Since Ox is adsorbed and the adsorbed NOx is reduced and desorbed in a stoichiometric or rich atmosphere, high NOx purification performance is obtained. A more preferred range is a lean atmosphere of 15
~ 50, stoichiometric or rich atmosphere is 10-14.8
It is.
【００３１】次に、本発明の排気ガス浄化装置につき、
図面を参照して詳細に説明する。この排気ガス浄化装置
は、上述した本発明のＮＯｘ吸蔵還元型三元触媒を使用
した装置である。Next, the exhaust gas purifying apparatus of the present invention will be described.
This will be described in detail with reference to the drawings. This exhaust gas purification apparatus is an apparatus using the above-described NOx storage reduction type three-way catalyst of the present invention.
【００３２】図１は、本発明に係るＮＯｘ吸蔵還元型三
元触媒を用いた排気ガス浄化装置の基本構成の一例を表
すブロック図である。同図において、この浄化装置で
は、内燃機関１の排気系の上流側から、第１空燃比検出
手段４、三元触媒２、ＮＯｘ吸蔵還元型三元触媒３、第
２空燃比検出手段５が順次配置されている。また、上記
空燃比検出手段４及び５に対し、第１空燃比フィードバ
ック手段６ａ及び第２空燃比フィードバック手段６ｂが
データ通信可能に接続されており、第１空燃比フィード
バック手段６ａは、第１空燃比検出手段４で検出された
排気空燃比に基づいて燃焼混合気の空燃比を目標空燃比
にフィードバック制御し、第２空燃比フィードバック手
段６ｂは、燃焼混合気の目標空燃比がリーンからストイ
キ又はリッチに切り換えられた直後において、第２空燃
比検出手段５で検出された排気空燃比に基づいて燃焼混
合気の空燃比を目標空燃比にフィードバック制御する。FIG. 1 is a block diagram showing an example of a basic configuration of an exhaust gas purifying apparatus using a NOx storage reduction type three-way catalyst according to the present invention. In this purification device, in the purification device, a first air-fuel ratio detecting means 4, a three-way catalyst 2, a NOx storage reduction type three-way catalyst 3, and a second air-fuel ratio detecting means 5 are arranged from the upstream side of the exhaust system of the internal combustion engine 1. They are arranged sequentially. A first air-fuel ratio feedback unit 6a and a second air-fuel ratio feedback unit 6b are connected to the air-fuel ratio detection units 4 and 5 so that data communication is possible, and the first air-fuel ratio feedback unit 6a is connected to the first air-fuel ratio feedback unit 6a. The air-fuel ratio of the combustion mixture is feedback-controlled to the target air-fuel ratio based on the exhaust air-fuel ratio detected by the fuel ratio detection unit 4, and the second air-fuel ratio feedback unit 6b changes the target air-fuel ratio of the combustion mixture from lean to stoichiometric or Immediately after the switching to rich, the air-fuel ratio of the combustion mixture is feedback-controlled to the target air-fuel ratio based on the exhaust air-fuel ratio detected by the second air-fuel ratio detecting means 5.
【００３３】図２は、本発明に係るＮＯｘ吸蔵還元型三
元触媒を用いた排気ガス浄化装置の一例を示すシステム
構成図である。なお、図１に示したものと実質的に同一
の部材には同一の符号を付し、その説明を省略する。図
２において、符号７は燃料噴射弁、８は排気管を示して
おり、この排気管８を介して、燃料噴射弁７、内燃機関
１、三元触媒２を内蔵したケーシング及びＮＯｘ吸蔵還
元型三元触媒３を内蔵したケーシングが連通している。
また、排気管８には、排気空燃比を検出する第１空燃比
センサ４ａ及び第２空燃比センサ５ａが、それぞれ三元
触媒２の上流、ＮＯｘ吸蔵還元型三元触媒３の下流に配
置されており、第１空燃比センサ４ａ、第２空燃比セン
サ５ａ及び燃料噴射弁７の出力は、上述した第１空燃比
フィードバック手段６ａ及び第２空燃比フィードバック
手段６ｂの機能を果たすコントロールユニット６に接続
されている。FIG. 2 is a system configuration diagram showing an example of an exhaust gas purifying apparatus using the NOx storage reduction type three-way catalyst according to the present invention. It is to be noted that the same members as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted. 2, reference numeral 7 denotes a fuel injection valve, and 8 denotes an exhaust pipe. Through this exhaust pipe 8, a casing containing the fuel injection valve 7, the internal combustion engine 1, the three-way catalyst 2, and a NOx storage reduction type are provided. The casing containing the three-way catalyst 3 communicates.
In the exhaust pipe 8, a first air-fuel ratio sensor 4a and a second air-fuel ratio sensor 5a for detecting an exhaust air-fuel ratio are disposed upstream of the three-way catalyst 2 and downstream of the NOx storage reduction type three-way catalyst 3, respectively. The outputs of the first air-fuel ratio sensor 4a, the second air-fuel ratio sensor 5a, and the fuel injection valve 7 are sent to the control unit 6, which performs the functions of the first air-fuel ratio feedback means 6a and the second air-fuel ratio feedback means 6b. It is connected.
【００３４】ここで、三元触媒２においては、酸素スト
レージ能力に寄与する成分であるセリア（ＣｅＯ2）の
量が調整されており、具体的には、従来の三元触媒で
は、５０〜６０ｇ／Ｌであるのに対し、５〜３０ｇ／
Ｌ、好ましくは５〜１５ｇ／Ｌに調整されている。Here, in the three-way catalyst 2, the amount of ceria (CeO 2 ), which is a component contributing to the oxygen storage capacity, is adjusted. Specifically, in the conventional three-way catalyst, 50 to 60 g is used. / L, 5 to 30 g /
L, preferably 5 to 15 g / L.
【００３５】また、ＮＯｘ吸蔵還元型三元触媒３は、上
述した本発明に係る触媒であり、排気空燃比がリーンの
ときに排気ガス中のＮＯｘを吸収し、この吸収したＮＯ
ｘを排気空燃比がストイキ又はリッチのときに還元処理
する触媒であり、上述のように、例えばアルミナを担持
基材とするが、この担体基材上には、セシウム、カリウ
ムに代表されるアルカリ金属、バリウムに代表されるア
ルカリ土類金属から選ばれた少なくとも１種と、白金、
パラジウム、ロジウムのような貴金属から選ばれた少な
くとも１種が担持されている。The NOx storage reduction type three-way catalyst 3 is the above-described catalyst according to the present invention, and absorbs NOx in the exhaust gas when the exhaust air-fuel ratio is lean.
x is a catalyst that performs a reduction treatment when the exhaust air-fuel ratio is stoichiometric or rich. As described above, for example, alumina is used as a supporting base material. On this supporting base material, an alkali represented by cesium and potassium is provided. Metal, at least one selected from alkaline earth metals represented by barium, platinum,
At least one selected from noble metals such as palladium and rhodium is supported.
【００３６】第１空燃比センサ４ａ及び第２空燃比セン
サ５ａとしては、排気ガス中の酸素濃度に基づいて排気
空燃比を検出するセンサを用いることができるが、理論
空燃比のみを検出するストイキセンサであってもよく、
また、排気空燃比を広域に検出できる広域空燃比センサ
であってもよい。As the first air-fuel ratio sensor 4a and the second air-fuel ratio sensor 5a, a sensor for detecting the exhaust air-fuel ratio based on the oxygen concentration in the exhaust gas can be used, but a stoichiometric sensor for detecting only the stoichiometric air-fuel ratio is used. May be a sensor,
Further, a wide-range air-fuel ratio sensor that can detect the exhaust air-fuel ratio in a wide range may be used.
【００３７】コントロールユニット６では、運転条件に
応じて目標空燃比を決定し、その目標空燃比の混合気が
形成されるように燃料噴射量（噴射パルス幅）が演算さ
れ、燃料噴射弁７に対する燃料噴射信号が決定される。
なお、目標空燃比としては、ストイキ及びリッチのみな
らず、リーンも設定することができる構成となってい
る。The control unit 6 determines the target air-fuel ratio in accordance with the operating conditions, calculates the fuel injection amount (injection pulse width) so as to form an air-fuel mixture of the target air-fuel ratio. A fuel injection signal is determined.
In addition, as the target air-fuel ratio, not only stoichiometric and rich but also lean can be set.
【００３８】また、コントロールユニット６では、通常
は第１空燃比センサ４ａで検出される排気空燃比を目標
空燃比に近づけるように、例えば、比例積分制御等によ
り、燃料噴射量を補正するための空燃比フィードバック
補正係数（操作量）を設定することなどが行われる（こ
の機能が第１空燃比フィードバック手段６ａに相当す
る。）。なお、目標空燃比のリーンからストイキ又はリ
ッチヘの切り換えは、運転条件（加速、負荷・回転の変
化）によって行われる他、本来目標空燃比としてリーン
空燃比が設定される条件下であっても、ＮＯｘ吸蔵還元
型三元触媒３におけるＮＯｘ吸収量が限界値に達してい
ると推定されるときは、一時的にリッチ制御が行える設
定になっており、ＮＯｘを還元処理するための一時的な
リッチ域への切り換えも含まれる。The control unit 6 normally corrects the fuel injection amount by, for example, proportional integral control so that the exhaust air-fuel ratio detected by the first air-fuel ratio sensor 4a approaches the target air-fuel ratio. For example, setting of an air-fuel ratio feedback correction coefficient (operating amount) is performed (this function corresponds to the first air-fuel ratio feedback means 6a). The switching of the target air-fuel ratio from lean to stoichiometric or rich is performed according to operating conditions (acceleration, changes in load / rotation), and even under conditions where a lean air-fuel ratio is originally set as the target air-fuel ratio. When it is estimated that the NOx absorption amount in the NOx storage reduction type three-way catalyst 3 has reached the limit value, the setting is such that the rich control can be temporarily performed, and the temporary rich control for reducing the NOx is performed. Switching to the area is also included.
【００３９】更に、コントロールユニット６は、目標空
燃比がリーンからストイキ又はリッチに切り換えられた
直後においては、第２空燃比センサ５ａの出力変化に応
じて上記空燃比フィードバック制御を実行するようなっ
ており、この機能は第２空燃比フィードバック手段６ｂ
が果たす機能に相当する。図３に、かかる第２空燃比フ
ィードバック手段６ｂによるフィードバック制御の一例
を示す。Further, immediately after the target air-fuel ratio is switched from lean to stoichiometric or rich, the control unit 6 executes the air-fuel ratio feedback control according to a change in the output of the second air-fuel ratio sensor 5a. This function is provided by the second air-fuel ratio feedback means 6b.
Function. FIG. 3 shows an example of feedback control by the second air-fuel ratio feedback means 6b.
【００４０】図３においては、まず、ステップ１１（以
下、「Ｓ１１」と略す。）で、ＮＯｘを還元処理するた
めの空燃比制御が必要かどうかが判別される。そして、
ＮＯｘを還元処理するための空燃比制御が必要であると
判断されると、目標空燃比がリーン雰囲気からリッチ雰
囲気に切り換えられる（Ｓ１２）。In FIG. 3, first, in step 11 (hereinafter abbreviated as "S11"), it is determined whether or not air-fuel ratio control for reducing NOx is necessary. And
If it is determined that air-fuel ratio control for reducing NOx is necessary, the target air-fuel ratio is switched from a lean atmosphere to a rich atmosphere (S12).
【００４１】次に、第１空燃比センサ４ａ及び第２空燃
比センサ５ａの出力が検出され（Ｓ１３）、第２空燃比
センサ５ａの出力が第１空燃比センサ４ａの出力よりリ
ッチであるかどうかが判断される（Ｓ１４）。第２空燃
比センサ５ａの出力が第１空燃比センサ４ａの出力より
リッチでない場合には、第２空燃比センサ５ａの出力が
第１空燃比センサ４ａの出力よりリッチになるまで空燃
比をリッチ化する。そして、第２空燃比センサ５ａの出
力が第１空燃比センサ４ａの出力よりリッチになれば、
ステップ１５に進み、空燃比をリーンに反転する（図６
参照）。Next, the outputs of the first air-fuel ratio sensor 4a and the second air-fuel ratio sensor 5a are detected (S13), and the output of the second air-fuel ratio sensor 5a is richer than the output of the first air-fuel ratio sensor 4a. It is determined whether or not (S14). If the output of the second air-fuel ratio sensor 5a is not richer than the output of the first air-fuel ratio sensor 4a, the air-fuel ratio is increased until the output of the second air-fuel ratio sensor 5a becomes richer than the output of the first air-fuel ratio sensor 4a. Become When the output of the second air-fuel ratio sensor 5a becomes richer than the output of the first air-fuel ratio sensor 4a,
Proceeding to step 15, the air-fuel ratio is reversed to lean (FIG.
reference).
【００４２】上述のステップ１３〜１５の処理を行う理
由は、以下の通りである。即ち、ＮＯｘ吸蔵還元型三元
触媒で還元処理がなされ、ＮＯｘ吸蔵還元型三元触媒か
らＮＯｘが脱離している間は、空燃比をリッチ化するた
めに供給されたＨＣ及びＣＯにより、それぞれ酸化と還
元が行われ、第２空燃比センサ５ａの出力がストイキ近
傍に保たれる。その後、ＮＯｘ吸蔵還元型三元触媒から
脱離するＮＯｘの量が減少すると、バランスが崩れ、第
２空燃比センサ５ａの出力がリッチ方向に動き、第１空
燃比センサ４ａと第２空燃比センサ５ａの出力が等しく
なった時点でＮＯｘの脱離が終了したと考えられる（図
５参照）。しかる後、第２空燃比センサの出力は第１空
燃比センサの出力よりリッチになるので、上述の如くリ
ーンへの反転を行えばよいことになる。The reasons for performing the above-mentioned steps 13 to 15 are as follows. That is, the reduction process is performed by the NOx storage reduction type three-way catalyst, and while NOx is desorbed from the NOx storage reduction type three-way catalyst, oxidation is performed by HC and CO supplied to enrich the air-fuel ratio, respectively. Is performed, and the output of the second air-fuel ratio sensor 5a is maintained near the stoichiometric state. Thereafter, when the amount of NOx desorbed from the NOx storage reduction type three-way catalyst decreases, the balance is lost, the output of the second air-fuel ratio sensor 5a moves in a rich direction, and the first air-fuel ratio sensor 4a and the second air-fuel ratio sensor It is considered that the desorption of NOx has ended when the outputs of 5a become equal (see FIG. 5). Thereafter, the output of the second air-fuel ratio sensor becomes richer than the output of the first air-fuel ratio sensor, so that it is sufficient to perform the reversion to lean as described above.
【００４３】上述のように、第１空燃比センサ４ａと第
２空燃比センサ５ａの出力をもとに目標空燃比をリッチ
からリーンに反転することにより、リーン運転時にＮＯ
ｘ吸蔵還元型三元触媒が吸収したＮＯｘを十分に脱離さ
せることができる。この際、上流側に配置された三元触
媒２に含まれる酸素ストレージ成分であるセリア（Ｃｅ
Ｏ2）を低減させるより、短時間で効果的にＮＯｘを脱
離させることが可能になる（図７参照）。また、第１空
燃比センサ４ａと第２空燃比センサ５ａの出力をもと
に、目標空燃比のリッチからリーンヘの反転を行うこと
で、温度等によりＮＯｘ吸収量が変化したり（図８参
照）、経時変化によってＮＯｘ吸収量や酸素ストレージ
量に変化があっても、ＮＯｘ吸収量に見合ったＮＯｘの
脱離条件を設定することができるようになる。As described above, by inverting the target air-fuel ratio from rich to lean based on the outputs of the first air-fuel ratio sensor 4a and the second air-fuel ratio sensor 5a, NO during lean operation is obtained.
NOx absorbed by the x storage reduction type three-way catalyst can be sufficiently desorbed. At this time, ceria (Ce) which is an oxygen storage component contained in the three-way catalyst 2 disposed on the upstream side
NOx can be effectively desorbed in a shorter time than reducing O 2 ) (see FIG. 7). Further, by inverting the target air-fuel ratio from rich to lean based on the outputs of the first air-fuel ratio sensor 4a and the second air-fuel ratio sensor 5a, the NOx absorption amount changes depending on the temperature or the like (see FIG. 8). ) Even if the NOx absorption amount or the oxygen storage amount changes due to a change with time, it becomes possible to set the NOx desorption conditions corresponding to the NOx absorption amount.
【００４４】次に、空燃比フィードバック制御の他の例
について説明する。図４は、第２空燃比フィードバック
手段６ｂによる制御の他の例を示すフローチャートであ
る。同図においては、まず、ステップ２１で、ＮＯｘを
還元処理するための空燃比制御が必要かどうかが判別さ
れる。かかる空燃比制御が必要であると判断されると、
運転状態（エンジン回転、燃料噴射量）からしきい値Ｓ
をマップより検出し（Ｓ２２）、次いで、目標空燃比が
リーンから理論空燃比又はリッチに切り換えられる（Ｓ
２３）。Next, another example of the air-fuel ratio feedback control will be described. FIG. 4 is a flowchart showing another example of the control by the second air-fuel ratio feedback means 6b. In the figure, first, at step 21, it is determined whether or not air-fuel ratio control for reducing NOx is necessary. If it is determined that such air-fuel ratio control is necessary,
Threshold value S based on operating conditions (engine rotation, fuel injection amount)
Is detected from the map (S22), and then the target air-fuel ratio is switched from lean to the stoichiometric air-fuel ratio or rich (S22).
23).
【００４５】次に、ステップ２４で、第１空燃比センサ
４ａ及び第２空燃比センサ５ａの出力を検出し、第２空
燃比センサ５ａの出力と第１空燃比センサ４ａの出力の
比率がしきい値Ｓ以上になったか否かを判別する（Ｓ２
５）。第２空燃比センサ５ａの出カと第１空燃比センサ
４ａの出力の比率が、しきい値Ｓより小さい場合には、
第２空燃比センサ５ａの出力が第１空燃比センサ４ａの
出力よりリッチになるまで空燃比をリッチ化する。第２
空燃比センサ５ａの出力と第１空燃比センサ４ａの出力
の比率が、しきい値Ｓ以上になったと判断すると、ステ
ップ２６に進み、空燃比をリーンに反転させる（図９参
照）。Next, in step 24, the outputs of the first air-fuel ratio sensor 4a and the second air-fuel ratio sensor 5a are detected, and the ratio between the output of the second air-fuel ratio sensor 5a and the output of the first air-fuel ratio sensor 4a is calculated. It is determined whether or not the threshold value S is exceeded (S2
5). When the ratio between the output of the second air-fuel ratio sensor 5a and the output of the first air-fuel ratio sensor 4a is smaller than the threshold value S,
The air-fuel ratio is made rich until the output of the second air-fuel ratio sensor 5a becomes richer than the output of the first air-fuel ratio sensor 4a. Second
If it is determined that the ratio between the output of the air-fuel ratio sensor 5a and the output of the first air-fuel ratio sensor 4a has exceeded the threshold value S, the process proceeds to step 26, where the air-fuel ratio is reversed to lean (see FIG. 9).
【００４６】上述のように、本例によれば、図３に示し
た例と同様に、第１空燃比センサ４ａと第２空燃比セン
サ５ａの出力をもとに目標空燃比をリッチからリーンに
反転することにより、リーン運転時にＮＯｘ吸蔵還元型
三元触媒が吸収したＮＯｘを十分に脱離させることがで
きる。また、上流側に配置された三元触媒に含まれる酸
素ストレージ成分であるセリア（ＣｅＯ2）を低減させ
るより、短時間で効果的にＮＯｘを脱離させることがで
きるようになる。更に、第１空燃比センサ４ａと第２空
燃比センサ５ａの出力の比率をもとに、目標空燃比のリ
ッチからリーンヘの反転を行うことで、温度等によりＮ
Ｏｘ吸収量が変化したり、経時変化によってＮＯｘ吸収
量や酸素ストレージ量に変化があってもＮＯｘ吸収量に
見合ったＮＯｘの脱離条件を設定することも可能であ
る。As described above, according to this embodiment, similarly to the example shown in FIG. 3, the target air-fuel ratio is changed from rich to lean based on the outputs of the first air-fuel ratio sensor 4a and the second air-fuel ratio sensor 5a. , The NOx absorbed by the NOx storage reduction type three-way catalyst during the lean operation can be sufficiently desorbed. Further, NOx can be effectively desorbed in a shorter time than reducing ceria (CeO 2 ), which is an oxygen storage component contained in the three-way catalyst disposed on the upstream side. Further, by inverting the target air-fuel ratio from rich to lean based on the ratio between the outputs of the first air-fuel ratio sensor 4a and the second air-fuel ratio sensor 5a, N
Even if the Ox absorption amount changes or the NOx absorption amount or the oxygen storage amount changes due to aging, it is also possible to set the NOx desorption conditions that match the NOx absorption amount.
【００４７】なお、図３及び図４に示した例では、それ
ぞれリッチスパイクの形状を図１０に示したような矩形
波としたが、図１１に示すように、リッチスパイクの形
状を三角波にしても、上述と同様な効果が得られる。In the examples shown in FIGS. 3 and 4, the shape of the rich spike is a rectangular wave as shown in FIG. 10, but as shown in FIG. 11, the shape of the rich spike is a triangular wave. Also, the same effect as described above can be obtained.
【００４８】[0048]
【実施例】以下、本発明を実施例、比較例及び試験例に
より詳細に説明するが、本発明はこれら実施例に限定さ
れるものではない。EXAMPLES Hereinafter, the present invention will be described in detail with reference to Examples, Comparative Examples, and Test Examples, but the present invention is not limited to these Examples.
【００４９】 （１）ＮＯｘ吸蔵還元型三元触媒の製造及び特性試験 （実施例１）硝酸パラジウム水溶液をに活性アルミナ粉
末に含浸し、乾燥後、空気中４００℃で１時間焼成し
て、パラジウム担持アルミナ粉末（粉末Ａ）を得た。こ
の粉末のパラジウム濃度は５．６重量％であった。ま
た、炭酸ランタンと炭酸コバルトの混合物にクエン酸を
加え、乾燥後、７００℃で焼成し、粉末（粉末Ｂ）を得
た。この粉末は金属原子比でランタン／コバルト＝０．
８／１であった。上述のようにして得られた粉末Ａ６０
０ｇ、粉末Ｂ３００ｇ、水９００ｇを磁性ボールミルに
投入し、混合粉砕してスラリー液を得た。(1) Production and Characteristic Test of NOx Storage Reduction Three-Way Catalyst (Example 1) An aqueous solution of palladium nitrate was impregnated with activated alumina powder, dried and calcined at 400 ° C. for 1 hour in the air to obtain palladium. A supported alumina powder (powder A) was obtained. The palladium concentration of this powder was 5.6% by weight. Further, citric acid was added to a mixture of lanthanum carbonate and cobalt carbonate, dried, and calcined at 700 ° C. to obtain a powder (powder B). This powder has a metal atom ratio of lanthanum / cobalt = 0.
8/1. Powder A60 obtained as described above
0 g, powder B (300 g) and water (900 g) were charged into a magnetic ball mill and mixed and pulverized to obtain a slurry liquid.
【００５０】このスラリー液をコーディライト質モノリ
ス担体（１．３Ｌ、４００セル）に付着させ、空気流に
てセル内の余剰のスラリーを除去し、１３０℃で乾燥し
た後、空気中４００℃で１時間焼成し、コート層重量１
５０ｇ／Ｌ−担体を得た。得られた１５０ｇ／Ｌ−担体
に酢酸バリウム水溶液を含浸し、１３０℃で乾燥した
後、空気中４００℃で１時間焼成して、炭酸バリウムを
担持した実施例１の触媒を得た。このようにして得られ
た本例の触媒のバリウム量は酸化物換算で２０ｇ／Ｌで
あった。This slurry liquid was adhered to a cordierite monolithic carrier (1.3 L, 400 cells), excess slurry in the cells was removed by an air stream, dried at 130 ° C., and then dried at 400 ° C. in air. Bake for 1 hour, coat layer weight 1
50 g / L-carrier was obtained. The obtained 150 g / L carrier was impregnated with an aqueous barium acetate solution, dried at 130 ° C., and calcined at 400 ° C. for 1 hour in the air to obtain a catalyst of Example 1 supporting barium carbonate. The barium content of the thus obtained catalyst of this example was 20 g / L in terms of oxide.
【００５１】本例並びに以下の実施例及び比較例の触媒
の組成は、表１にまとめて示す。The compositions of the catalysts of this example and the following examples and comparative examples are summarized in Table 1.
【００５２】（比較例１）粉末Ｂを活性アルミナに代え
た以外は、実施例１と同様の操作を繰り返し、本例の触
媒を得た。Comparative Example 1 The same operation as in Example 1 was repeated, except that the powder B was changed to activated alumina, to obtain a catalyst of this example.
【００５３】（比較例２）バリウム担持を行わなかった
以外は、実施例１と同様の操作を繰り返し、本例の触媒
を得た。Comparative Example 2 The same operation as in Example 1 was repeated, except that barium was not supported, to obtain a catalyst of this example.
【００５４】（実施例２）粉末ＢのＬａをＣｅとした以
外は、実施例１と同様の操作を繰り返し、本例の触媒を
得た。(Example 2) The same operation as in Example 1 was repeated except that La of powder B was changed to Ce, to obtain a catalyst of this example.
【００５５】（実施例３）粉末ＢのＬａをＮｄとした以
外は、実施例１と同様の操作を繰り返し、本例の触媒を
得た。Example 3 The same operation as in Example 1 was repeated except that La of powder B was changed to Nd, to obtain a catalyst of this example.
【００５６】（実施例４）粉末ＢのＣｏをＭｎとした以
外は、実施例１と同様の操作を繰り返し、本例の触媒を
得た。Example 4 The same operation as in Example 1 was repeated, except that Mn was used as the Co in the powder B, to obtain a catalyst of this example.
【００５７】（実施例５）粉末ＢのＣｏをＦｅとした以
外は、実施例１と同様の操作を繰り返し、本例の触媒を
得た。(Example 5) The same operation as in Example 1 was repeated except that Co in powder B was changed to Fe, to obtain a catalyst of this example.
【００５８】（実施例６）粉末ＢのＣｏをＮｉとした以
外は、実施例１と同様の操作を繰り返し、本例の触媒を
得た。Example 6 The same operation as in Example 1 was repeated, except that Ni in the powder B was changed to Ni, to obtain a catalyst of this example.
【００５９】（実施例７）ＢａをＫとした以外は、実施
例１と同様の操作を繰り返し、本例の触媒を得た。Example 7 The same operation as in Example 1 was repeated, except that Ba was changed to K, to obtain a catalyst of this example.
【００６０】（実施例８）ＢａをＳｒとした以外は、実
施例１と同様の操作を繰り返し、本例の触媒を得た。(Example 8) The same operation as in Example 1 was repeated except that Ba was changed to Sr, to obtain a catalyst of this example.
【００６１】（実施例９）ＢａをＣｓとした以外は、実
施例１と同様の操作を繰り返し、本例の触媒を得た。(Example 9) The same operation as in Example 1 was repeated except that Ba was changed to Cs, to obtain a catalyst of this example.
【００６２】（実施例１０）ＢａをＣｓとＭｇの混合物
（酸化物換算の重量比で１：１）とした以外は、実施例
１と同様の操作を繰り返し、本例の触媒を得た。Example 10 A catalyst of this example was obtained by repeating the same operation as in Example 1 except that Ba was changed to a mixture of Cs and Mg (weight ratio in terms of oxide: 1: 1).
【００６３】（実施例１１）硝酸ロジウム水溶液を活性
アルミナに含浸し、乾燥後、空気中４００℃で１時間焼
成して、ロジウム担持粉末（粉末Ｃ）を得た。この粉末
のロジウム濃度は２．０重量％であった。ジニトロジア
ンミン白金水溶液を活性アルミナに含浸し、乾燥後、空
気中４００℃で１時間焼成して、白金担持粉末（粉末
Ｄ）を得た。この粉末の白金濃度は４．０重量％であっ
た。上述のようにして得られた粉末Ｃ１０６ｇ、粉末Ｄ
２６５ｇ、粉末Ｂ３００ｇ、活性アルミナ粉末２２９
ｇ、水９００ｇを磁性ボールミルに投入し、混合粉砕し
てスラリー液を得た。Example 11 An activated rhodium nitrate aqueous solution was impregnated into activated alumina, dried, and calcined in air at 400 ° C. for 1 hour to obtain a rhodium-carrying powder (powder C). The rhodium concentration of this powder was 2.0% by weight. Activated alumina was impregnated with an aqueous solution of dinitrodiammine platinum, dried, and calcined in air at 400 ° C. for 1 hour to obtain a platinum-supported powder (powder D). The platinum concentration of this powder was 4.0% by weight. 106 g of powder C, powder D obtained as described above
265 g, powder B 300 g, activated alumina powder 229
g and water 900 g were charged into a magnetic ball mill and mixed and pulverized to obtain a slurry liquid.
【００６４】このスラリー液をコーディライト質モノリ
ス担体（１．３Ｌ、４００セル）に付着させ、空気流に
てセル内の余剰のスラリーを除去し、１３０℃で乾燥し
た後、４００℃で１時間焼成し、コート層重量１５０ｇ
／Ｌ−担体を得た。得られた１５０ｇ／Ｌ−担体に酢酸
バリウム水溶液を含浸し、１３０℃で乾燥した後、空気
中４００℃で１時間焼成して、炭酸バリウムを担持した
実施例１１の触媒を得た。このようにして得られた本例
の触媒のバリウム量は酸化物換算で２０ｇ／Ｌであっ
た。This slurry liquid was attached to a cordierite type monolithic carrier (1.3 L, 400 cells), excess slurry in the cells was removed with an air stream, dried at 130 ° C., and then dried at 400 ° C. for 1 hour. Baking, coat layer weight 150g
/ L-carrier was obtained. The obtained 150 g / L carrier was impregnated with an aqueous barium acetate solution, dried at 130 ° C., and calcined at 400 ° C. for 1 hour in the air to obtain a catalyst of Example 11 supporting barium carbonate. The barium content of the thus obtained catalyst of this example was 20 g / L in terms of oxide.
【００６５】[0065]
【表１】 [Table 1]
【００６６】（触媒特性試験１）上述のようにして得ら
れた各例の触媒につき、下記の方法で試験を行った。得
られた結果を表２に示す。 （耐久方法）排気量４４００ｃｃのエンジンの排気系に
各例の触媒を装着し、触媒入口温度を７００℃とし、５
０時間運転した。 （評価方法）排気量２０００ｃｃのエンジンの排気系に
各例の触媒を装着し、Ａ／Ｆ＝１１．０を１０秒間、Ａ
／Ｆ＝２２を３０秒間を交互に繰り返すように運転し、
触媒入口温度を３５０℃とし、この切り換え運転１サイ
クルのトータル転化率を求めた。(Catalyst Characteristics Test 1) The catalysts of the respective examples obtained as described above were tested by the following methods. Table 2 shows the obtained results. (Durability method) The catalyst of each example was mounted on the exhaust system of a 4400 cc displacement engine, and the catalyst inlet temperature was set to 700 ° C.
Driving for 0 hours. (Evaluation method) The catalyst of each example was mounted on an exhaust system of an engine with a displacement of 2000 cc, and A / F = 11.0 was set to A for 10 seconds.
Driving so that / F = 22 alternately repeats for 30 seconds,
The catalyst inlet temperature was set to 350 ° C., and the total conversion in one cycle of this switching operation was determined.
【００６７】[0067]
【表２】 [Table 2]
【００６８】（実施例１２）硝酸パラジウム水溶液を活
性アルミナ粉末に含浸し、乾燥後、空気中４００℃で１
時間焼成して、パラジウム担持アルミナ粉末（粉末Ｅ）
を得た。この粉末のパラジウム濃度は５．０重量％であ
った。また、炭酸ランタンと炭酸バリウムと炭酸コバル
トの混合物にクエン酸を加え、乾燥後、７００℃で焼成
し、粉末（粉末Ｆ）を得た。この粉末は金属原子比でラ
ンタン／バリウム／コバルト＝２／７／１０であった。
更に、ジニトロジアンミン白金水溶液を粉末Ｆに含浸
し、乾燥後、空気中４００℃で１時間焼成して、白金担
持粉末Ｆ（粉末Ｇ）を得た。この粉末の白金濃度は、
５．０重量％であった。上述のようにして得られた粉末
Ｅ５４４ｇ、粉末Ｇ３４２ｇ、活性アルミナ粉末１２
ｇ、水９０２ｇを磁性ボールミルに投入し、混合粉砕し
てスラリー液を得た。Example 12 An activated alumina powder was impregnated with an aqueous solution of palladium nitrate, dried, and dried at 400 ° C. in air.
Calcined for palladium on alumina powder (powder E)
I got The palladium concentration of this powder was 5.0% by weight. Further, citric acid was added to a mixture of lanthanum carbonate, barium carbonate, and cobalt carbonate, dried, and calcined at 700 ° C. to obtain a powder (powder F). This powder had a metal atomic ratio of lanthanum / barium / cobalt = 2/7/10.
Further, the powder F was impregnated with an aqueous solution of dinitrodiammine platinum, dried, and calcined at 400 ° C. for 1 hour in the air to obtain a platinum-supporting powder F (powder G). The platinum concentration of this powder is
It was 5.0% by weight. 544 g of powder E, 342 g of powder G, and 12 parts of activated alumina powder obtained as described above.
g and 902 g of water were charged into a magnetic ball mill and mixed and pulverized to obtain a slurry liquid.
【００６９】このスラリー液をコーディライト質モノリ
ス担体（１．３Ｌ、４００セル）に付着させ、空気流に
てセル内の余剰のスラリーを除去し、１３０℃で乾燥し
た後、空気中４００℃で１時間焼成して、コート層重量
１０５ｇ／Ｌを担持した実施例１２の触媒を得た。この
ようにして得られた本例の触媒は、触媒１Ｌ当たり、粉
末Ｅを６４ｇ、粉末Ｇを４０ｇ含有する。なお、本例並
びに以下の実施例及び比較例の触媒の組成は、表３にま
とめて示す。This slurry liquid was attached to a cordierite type monolithic carrier (1.3 L, 400 cells), excess slurry in the cells was removed with an air stream, dried at 130 ° C., and then dried in air at 400 ° C. The catalyst was fired for 1 hour to obtain a catalyst of Example 12 supporting a coat layer weight of 105 g / L. The catalyst of this example thus obtained contains 64 g of powder E and 40 g of powder G per liter of the catalyst. Table 3 shows the compositions of the catalysts of this example and the following examples and comparative examples.
【００７０】（比較例３）実施例１２と同様の操作を行
い、パラジウム担持アルミナ粉末（粉末Ｅ）を得た。ま
た、ジニトロジアンミン白金水溶液を活性アルミナ粉末
に含浸し、乾燥後、空気中４００℃で１時間焼成して、
白金担持アルミナ粉末（粉末Ｈ）を得た。この粉末の白
金濃度は、５．０重量％であった。上述のようにして得
られた粉末Ｅ５４４ｇ、粉末Ｈ３４２ｇ、活性アルミナ
粉末１２ｇ、水９０２ｇを磁性ボールミルに投入し、混
合粉砕してスラリー液を得た。Comparative Example 3 The same operation as in Example 12 was performed to obtain a palladium-supported alumina powder (powder E). Also, the activated alumina powder is impregnated with an aqueous solution of dinitrodiammine platinum, dried, and calcined at 400 ° C. for 1 hour in the air.
A platinum-supported alumina powder (powder H) was obtained. The platinum concentration of this powder was 5.0% by weight. 544 g of powder E, 342 g of powder H, 12 g of activated alumina powder, and 902 g of water obtained as described above were charged into a magnetic ball mill and mixed and pulverized to obtain a slurry liquid.
【００７１】このスラリー液をコーディライト質モノリ
ス担体（１．３Ｌ、４００セル）に付着させ、空気流に
てセル内の余剰のスラリーを除去し、１３０℃で乾燥し
た後、空気中４００℃で１時間焼成して、コート層重量
１０５ｇ／Ｌを担持した比較例３を得た。このようにし
て得られた本例の触媒は、触媒１Ｌ当たり、粉末Ｅを６
４ｇ、粉末Ｈを４０ｇ含有する。This slurry liquid was attached to a cordierite type monolithic carrier (1.3 L, 400 cells), excess slurry in the cells was removed by an air stream, dried at 130 ° C., and then dried at 400 ° C. in air. After baking for 1 hour, Comparative Example 3 carrying a coat layer weight of 105 g / L was obtained. The catalyst of the present example thus obtained contained 6 parts of powder E per liter of catalyst.
4 g, containing 40 g of powder H.
【００７２】（実施例１３）粉末Ｅを２７２ｇ、粉末Ｇ
を１７１ｇ、活性アルミナ粉末を４５６ｇ、水を８９８
ｇとした以外は、実施例１２と同様の操作を繰り返し、
コート層重量２１０ｇ／Ｌを担持した実施例１３を得
た。このようにして得られた本例の触媒は、触媒１Ｌ当
たり、粉末Ｅを６４ｇ、粉末Ｆを４０ｇ含有する。(Example 13) Powder 272 g of powder E and powder G
171 g, activated alumina powder 456 g, water 898
g, and the same operation as in Example 12 was repeated, except that
Example 13 having a coat layer weight of 210 g / L was obtained. The catalyst of this example thus obtained contains 64 g of powder E and 40 g of powder F per liter of the catalyst.
【００７３】（実施例１４）硝酸パラジウム水溶液を活
性アルミナ粉末に含浸し、乾燥後、空気中４００℃で１
時間焼成して、パラジウム担持アルミナ粉末（粉末
Ｅ’）を得た。この粉末Ｅ’のパラジウム濃度は２．５
重量％であった。また、ジニトロジアンミン白金水溶液
を粉末Ｆに含浸し、乾燥後、空気中４００℃で１時間焼
成し、白金担持アルミナ粉末（粉末Ｇ’）を得た。この
粉末Ｇ’の白金濃度は、２．５重量％であった。上述の
ようにして得られた粉末Ｅ’５４５ｇ、粉末Ｇ’３４３
ｇ、活性アルミナ粉末２４ｇ、水８８８ｇを磁性ボール
ミルに投入し、混合粉砕してスラリー液を得た。Example 14 An activated alumina powder was impregnated with an aqueous solution of palladium nitrate, dried, and dried at 400 ° C. in air.
After baking for an hour, an alumina powder carrying palladium (powder E ') was obtained. The palladium concentration of this powder E 'was 2.5
% By weight. Powder F was impregnated with an aqueous solution of dinitrodiammine platinum, dried, and calcined at 400 ° C. for 1 hour in the air to obtain a platinum-supported alumina powder (powder G ′). The platinum concentration of this powder G ′ was 2.5% by weight. 545 g of powder E ′ obtained as described above, powder G′343
g, activated alumina powder 24 g and water 888 g were charged into a magnetic ball mill and mixed and pulverized to obtain a slurry liquid.
【００７４】このスラリー液をコーディライト質モノリ
ス担体（１．３Ｌ、４００セル）に付着させ、空気流に
てセル内の余剰のスラリーを除去し、１３０℃で乾燥し
た後、空気中４００℃で１時間焼成して、コート層重量
２１０ｇ／Ｌを担持した実施例１４を得た。このように
して得られた本例の触媒は、触媒１Ｌ当たり、粉末Ｅ’
を１２５ｇ、粉末Ｇ’を７９ｇ含有する。This slurry liquid was attached to a cordierite type monolithic carrier (1.3 L, 400 cells), excess slurry in the cells was removed by an air stream, dried at 130 ° C., and then dried at 400 ° C. in air. After sintering for one hour, Example 14 was obtained in which the coat layer weight was 210 g / L. The catalyst of the present example thus obtained was mixed with powder E ′ per liter of the catalyst.
125 g and 79 g of powder G '.
【００７５】（実施例１５）粉末Ｅ’を３６３ｇ、粉末
Ｇ’を２２９ｇ、活性アルミナ粉末を３０８ｇ、水を９
００ｇとした以外は、実施例１４と同様の操作を繰り返
し、コート層重量３１５ｇ／Ｌを担持した実施例１５を
得た。このようにして得られた本例の触媒は、触媒１Ｌ
当たり、粉末Ｅ’を１２７ｇ、粉末Ｇ’を８０ｇ含有す
る。(Example 15) 363 g of powder E ', 229 g of powder G', 308 g of activated alumina powder and 9 parts of water
The same operation as in Example 14 was repeated except that the amount was set to 00 g, to obtain Example 15 in which the coat layer weight was 315 g / L. The catalyst of the present example thus obtained is 1 L of catalyst
Per unit, 127 g of powder E 'and 80 g of powder G'.
【００７６】（実施例１６）粉末ＦのＢａをＣｓとした
以外は、実施例１５と同様の操作を繰り返し、本例の触
媒を得た。Example 16 The same operation as in Example 15 was repeated except that the Ba of the powder F was changed to Cs, to obtain a catalyst of this example.
【００７７】（実施例１７）硝酸ロジウム水溶液を活性
アルミナ粉末に含浸し、乾燥後、空気中４００℃で１時
間焼成して、ロジウム担持アルミナ粉末（粉末Ｉ）を得
た。この粉末ＩのＲｈ濃度は４．０重量％であった。得
られた粉末Ｉ３３ｇ、粉末Ｅ’４２２ｇ、粉末Ｇ’２２
９ｇ、活性アルミナ粉末１９０ｇ、水９２４ｇを磁性ボ
ールミルに投入し、混合粉砕してスラリー液を得た。Example 17 An activated rhodium nitrate aqueous solution was impregnated with activated alumina powder, dried and calcined in air at 400 ° C. for 1 hour to obtain rhodium-supported alumina powder (powder I). The Rh concentration of this powder I was 4.0% by weight. 33 g of obtained powder I, 422 g of powder E ', and powder G'22
9 g, 190 g of activated alumina powder and 924 g of water were charged into a magnetic ball mill and mixed and pulverized to obtain a slurry liquid.
【００７８】このスラリー液をコーディライト質モノリ
ス担体（１．３Ｌ、４００セル）に付着させ、空気流に
てセル内の余剰のスラリーを除去し、１３０℃で乾燥し
た後、空気中４００℃で１時間焼成して、コート層重量
３１５ｇ／Ｌを担持した実施例１７を得た。This slurry liquid was attached to a cordierite type monolithic carrier (1.3 L, 400 cells), excess slurry in the cells was removed by an air stream, dried at 130 ° C., and then dried at 400 ° C. in air. After sintering for one hour, Example 17 was obtained, in which the weight of the coat layer was 315 g / L.
【００７９】（実施例１８）粉末ＦのＢａをＣｓとした
以外は、実施例１７と同様の操作を繰り返し、本例の触
媒を得た。Example 18 The same operation as in Example 17 was repeated, except that the powder F was changed from Ba to Cs, to obtain a catalyst of this example.
【００８０】[0080]
【表３】 [Table 3]
【００８１】（触媒特性試験２）上述のようにして得ら
れた実施例１２〜１７及び比較例３の触媒につき、下記
の方法で試験を行った。得られた結果を表４に示す。な
お、表４における数字は、いずれも百分率で表されたも
のである。 （耐久方法）試験例１と同一の方法を行った。 （評価方法）試験例１と同一の方法を行った。(Catalyst Property Test 2) The catalysts of Examples 12 to 17 and Comparative Example 3 obtained as described above were tested by the following method. Table 4 shows the obtained results. The numbers in Table 4 are all expressed in percentage. (Durability method) The same method as in Test Example 1 was performed. (Evaluation method) The same method as in Test Example 1 was performed.
【００８２】[0082]
【表４】 [Table 4]
【００８３】（２）ＮＯｘ吸蔵還元型三元触媒を用いた
排気ガス浄化装置の性能試験 （実施例１９）バリウムをセシウムに代えた以外は、実
施例１１と同様の操作を繰り返し、本例の触媒を得た。(2) Performance test of an exhaust gas purifying apparatus using a NOx storage reduction type three-way catalyst (Example 19) The same operation as in Example 11 was repeated except that barium was replaced with cesium. A catalyst was obtained.
【００８４】（実施例２０）まず、活性アルミナ粉末に
セリウム８重量％、ジルコニウム４重量％、ランタン４
重量％を担持焼成し、セリウム・ジルコニウム・ランタ
ン・アルミナ粉末を得た。この粉末を撹拌しながら硝酸
パラジウム水溶液を噴霧し、その後焼成してパラジウム
１．１６重量％を担持したパラジウム担持アルミナ粉末
を得た。このようにして得られたパラジウム担持アルミ
ナ粉末９００ｇ及び硝酸酸性アルミナゾル９００ｇと酢
酸１０重量％水溶液１２００ｇを磁性ボールミルに投入
し、混合粉砕してスラリー液を得た。Example 20 First, 8% by weight of cerium, 4% by weight of zirconium and 4% by weight of lanthanum were added to activated alumina powder.
The cerium / zirconium / lanthanum / alumina powder was obtained by supporting and sintering the weight%. An aqueous palladium nitrate solution was sprayed on the powder while stirring, and then calcined to obtain a palladium-supported alumina powder supporting 1.16% by weight of palladium. 900 g of the thus-obtained palladium-supported alumina powder, 900 g of nitric acid acidic alumina sol, and 1200 g of a 10% by weight aqueous solution of acetic acid were charged into a magnetic ball mill and mixed and pulverized to obtain a slurry liquid.
【００８５】このスラリー液をコーディライト質モノリ
ス担体に塗布し、空気流にてセル内の余剰のスラリーを
取り除いて乾燥し、４００℃で１時間焼成し、コート層
重量１４２ｇ／Ｌのモノリス担体を得た。This slurry liquid was applied to a cordierite type monolithic carrier, excess slurry in the cell was removed with an air stream, dried, and baked at 400 ° C. for 1 hour to obtain a monolithic carrier having a coat layer weight of 142 g / L. Obtained.
【００８６】次に、活性アルミナ粉末に硝酸ロジウム水
溶液を噴霧し、その後焼成してロジウム１．０重量％を
担持したロジウム担持アルミナを得た。このようにして
得られたロジウム担持アルミナ粉末１１４ｇ、上記パラ
ジウム担持アルミナ粉末２７９ｇ及び硝酸酸性アルミナ
ゾル４００ｇと酢酸１０重量％水溶液９００ｇを磁性ボ
ールミルに投入し、混合粉砕してスラリー液を得た。Next, an aqueous rhodium nitrate solution was sprayed on the activated alumina powder, followed by calcination to obtain rhodium-supported alumina carrying 1.0% by weight of rhodium. 114 g of the rhodium-supported alumina powder thus obtained, 279 g of the palladium-supported alumina powder, 400 g of nitric acid acidic alumina sol and 900 g of a 10% by weight aqueous solution of acetic acid were charged into a magnetic ball mill and mixed and pulverized to obtain a slurry liquid.
【００８７】このスラリー液を上記コート層重量１４２
ｇ／Ｌのモノリス担体に塗布し、空気流にてセル内の余
剰のスラリーを取り除き、乾燥した後、４００℃で１時
間焼成し、コート層重量２１３ｇ／Ｌを担体した実施例
２０を得た。This slurry liquid was coated with the above-mentioned coat layer weight 142.
g / L of a monolithic carrier, the excess slurry in the cell was removed by an air flow, dried, and then baked at 400 ° C. for 1 hour to obtain Example 20 in which the coat layer weight was 213 g / L. .
【００８８】（実施例２１）セリウム８重量％をセリウ
ム４重量％に代えた以外は、実施例２０と同様の操作を
繰り返し、本例の触媒を得た。Example 21 The same operation as in Example 20 was repeated, except that 8% by weight of cerium was replaced by 4% by weight of cerium, to obtain a catalyst of this example.
【００８９】（実施例２２）まず、活性アルミナ粉末に
硝酸パラジウム水溶液を噴霧し、その後焼成してパラジ
ウム１．１９重量％を担持したパラジウム１．１９重量
％担持アルミナ粉末を得た。これとは別に、硝酸ジルコ
ニウムと硝酸セリウムを含む水溶液にアンモニア水溶液
を添加し、生成した沈殿物を焼成して、ジルコニア・セ
リウム複合酸化物を得た。このようにして得られたパラ
ジウム１．１９重量％担持アルミナ粉末７７２ｇ及びジ
ルコニア・セリウム複合酸化物２１４ｇと酢酸１０重量
％水溶液１２００ｇを磁性ボールミルに投入し、混合粉
砕してスラリー液を得た。Example 22 First, an aqueous palladium nitrate solution was sprayed on activated alumina powder, and then calcined to obtain 1.19% by weight palladium-supported alumina powder supporting 1.19% by weight of palladium. Separately, an aqueous ammonia solution was added to an aqueous solution containing zirconium nitrate and cerium nitrate, and the resulting precipitate was fired to obtain a zirconia-cerium composite oxide. The thus-obtained 1.19% by weight of palladium-supported alumina powder (772 g), zirconia / cerium composite oxide (214 g), and acetic acid (10% by weight) aqueous solution (1200 g) were charged into a magnetic ball mill and mixed and pulverized to obtain a slurry liquid.
【００９０】このスラリー液をコーディライト質モノリ
ス担体に塗布し、空気流にてセル内の余剰のスラリーを
取り除いて乾燥し、４００℃で１時間焼成し、コート層
重量１４０ｇ／Ｌのモノリス担体を得た。This slurry liquid was applied to a cordierite-based monolithic carrier, excess slurry in the cell was removed with an air stream, dried, and calcined at 400 ° C. for 1 hour to obtain a monolithic carrier having a coat layer weight of 140 g / L. Obtained.
【００９１】次に、活性アルミナ粉末に硝酸ロジウム水
溶液を噴霧し、その後焼成してロジウム１．０重量％を
担持したロジウム担持アルミナを得た。これとは別に、
活性アルミナ粉末に硝酸パラジウム水溶液を噴霧し、そ
の後焼成してパラジウム１．０７重量％を担持したパラ
ジウム１．０７重量％担持アルミナ粉末を得た。このよ
うにして得られたロジウム担持アルミナ粉末１１４ｇ、
パラジウム１．０７重量％担持アルミナ粉末３０６ｇ及
び上記ジルコニア・セリウム複合酸化物２４０ｇと酢酸
１０重量％水溶液９００ｇを磁性ボールミルに投入し、
混合粉砕してスラリー液を得た。Next, an aqueous rhodium nitrate solution was sprayed on the activated alumina powder, and then fired to obtain rhodium-supported alumina carrying 1.0% by weight of rhodium. Aside from this,
An aqueous solution of palladium nitrate was sprayed on the activated alumina powder and then calcined to obtain an alumina powder carrying 1.07% by weight of palladium carrying 1.07% by weight of palladium. 114 g of the rhodium-supported alumina powder thus obtained,
306 g of alumina powder supported on 1.07% by weight of palladium, 240 g of the zirconia / cerium composite oxide, and 900 g of an aqueous solution of 10% by weight of acetic acid were charged into a magnetic ball mill,
The mixture was pulverized to obtain a slurry liquid.
【００９２】このスラリー液を上記コート層重量１４０
ｇ／Ｌのモノリス担体に塗布し、空気流にてセル内の余
剰のスラリーを取り除き、乾燥した後、４００℃で１時
間焼成し、コート層総重量２１０ｇ／Ｌを担持した実施
例２２を得た。This slurry liquid was applied to the coating layer having a weight of 140.
g / L of a monolithic carrier, the excess slurry in the cell was removed by an air stream, dried, and baked at 400 ° C. for 1 hour to obtain Example 22 carrying a total weight of 210 g / L of the coat layer. Was.
【００９３】（比較例４）ジルコニア・セリウム複合酸
化物２１４ｇをジルコニア・セリウム複合酸化物４２８
ｇに代え、上記ジルコニア・セリウム複合酸化物２４０
ｇを上記ジルコニア・セリウム複合酸化物４８０ｇに代
えた以外は、実施例２２と同様の操作を繰り返し、本例
の触媒を得た。Comparative Example 4 214 g of zirconia / cerium composite oxide was replaced with zirconia / cerium composite oxide 428
g, the zirconia-cerium composite oxide 240
The same operation as in Example 22 was repeated, except that g was changed to 480 g of the zirconia-cerium composite oxide, to obtain a catalyst of this example.
【００９４】（比較例５）ジルコニア・セリウム複合酸
化物２１４ｇをジルコニア・セリウム複合酸化物０ｇに
代え、上記ジルコニア・セリウム複合酸化物２４０ｇを
上記ジルコニア・セリウム複合酸化物０ｇに代えた以外
は、実施例２２と同様の操作を繰り返し、本例の触媒を
得た。(Comparative Example 5) A zirconia-cerium composite oxide was replaced with 0 g of the zirconia-cerium composite oxide and 214 g of the zirconia-cerium composite oxide was replaced with 0 g of the zirconia-cerium composite oxide. The same operation as in Example 22 was repeated to obtain a catalyst of this example.
【００９５】（装置性能試験）上述のようにして得られ
た実施例１、９、１１及び１９〜２２並びに比較例４及
び５の触媒につき、下記の方法で試験を行った。得られ
た結果を表５に示す。 （耐久方法）排気量４４００ｃｃのエンジンの排気系に
各例の触媒を装着し、触媒入口温度を７００℃とし、５
０時間運転した。 （評価方法）排気量２０００ｃｃのエンジンの排気系の
同一流路中に、表５に示すように触媒を２個装着し、Ａ
／Ｆ＝１１．０、Ａ／Ｆ＝２２を交互に繰り返すように
運転し、触媒入口温度を上流側４５０℃、下流側３５０
℃とし、この切り換え運転１サイクルのトータル転化率
を求めた。(Equipment Performance Test) The catalysts of Examples 1, 9, 11, and 19 to 22 and Comparative Examples 4 and 5 obtained as described above were tested by the following method. Table 5 shows the obtained results. (Durability method) The catalyst of each example was mounted on the exhaust system of a 4400 cc displacement engine, and the catalyst inlet temperature was set to 700 ° C.
Driving for 0 hours. (Evaluation method) Two catalysts were mounted as shown in Table 5 in the same flow path of the exhaust system of an engine with a displacement of 2000 cc.
/F=11.0 and A / F = 22 are alternately repeated, and the catalyst inlet temperature is set to 450 ° C. on the upstream side and 350 ° C. on the downstream side.
° C, and the total conversion in one cycle of this switching operation was determined.
【００９６】[0096]
【表５】 [Table 5]
【００９７】表５の結果から、セリア及びセリアを含む
複合酸化物の量が触媒１リットル当たり５〜３０ｇであ
る三元触媒を使用した場合（実施例２３〜２８）は、Ｈ
Ｃの転化率及びＮＯｘの転化率はいずれも良好であるの
に対し、セリア及びセリアを含む複合酸化物の量が触媒
１リットル当たり３０ｇより多い三元触媒を使用した場
合（比較例６）には、ＨＣの転化率は良好であるが、Ｎ
Ｏｘの転化率が低下し、セリア及びセリアを含む複合酸
化物の量が触媒１リットル当たり５ｇより少ない三元触
媒を使用した場合（比較例７）には、ＮＯｘの転化率は
良好であるが、ＨＣの転化率が低下することがわかっ
た。From the results shown in Table 5, when using a three-way catalyst in which the amount of ceria and the complex oxide containing ceria is 5 to 30 g per liter of catalyst (Examples 23 to 28), H
While the conversion rate of C and the conversion rate of NOx are both good, when a three-way catalyst in which the amount of ceria and the complex oxide containing ceria is more than 30 g per liter of catalyst is used (Comparative Example 6). Means that the conversion of HC is good,
When the conversion of Ox is reduced and a three-way catalyst is used in which the amount of ceria and the composite oxide containing ceria is less than 5 g per liter of catalyst (Comparative Example 7), the conversion of NOx is good. , It was found that the conversion of HC decreased.
【００９８】[0098]
【発明の効果】以上説明してきたように、本発明によれ
ば、所定の複合酸化物と貴金属元素とを適切に共存させ
ることなどしたため、リーン雰囲気でのＮＯｘ浄化性能
に優れるＮＯｘ吸蔵還元型三元触媒を提供することがで
きる。As described above, according to the present invention, a predetermined composite oxide and a noble metal element are made to coexist appropriately, and the NOx storage-reduction type catalyst having excellent NOx purification performance in a lean atmosphere. A raw catalyst can be provided.
【００９９】また、本発明によれば、ＮＯｘ吸蔵還元型
三元触媒の上流側に配置された三元触媒中の酸素ストレ
ージ能力に寄与する成分の量を低減することなどしたた
め、排気空燃比がリーンからリッチに切り換わった際に
ＮＯｘ吸蔵還元型三元触媒に十分なＨＣ及びＣＯが供給
できるようになり、ＮＯｘの浄化率が向上する排気ガス
浄化装置を提供することができる。Further, according to the present invention, since the amount of the component contributing to the oxygen storage capacity in the three-way catalyst disposed on the upstream side of the NOx storage reduction type three-way catalyst is reduced, the exhaust air-fuel ratio is reduced. When switching from lean to rich, sufficient HC and CO can be supplied to the NOx storage reduction type three-way catalyst, and an exhaust gas purifying apparatus with an improved NOx purification rate can be provided.
【０１００】更に、本発明によれば、排気空燃比に基づ
いて燃焼混合気の空燃比を目標空燃比にフィードバック
制御する空燃比フィードバック手段を設けることなどを
したため、ＨＣ及びＣＯの浄化性能の悪化を最小限に抑
えることができる排気ガス浄化装置を提供することも可
能となる。Further, according to the present invention, air-fuel ratio feedback means for feedback-controlling the air-fuel ratio of the combustion mixture to the target air-fuel ratio based on the exhaust air-fuel ratio is provided, so that the purification performance of HC and CO deteriorates. It is also possible to provide an exhaust gas purifying apparatus capable of minimizing the exhaust gas.
【０１０１】[0101]
【図１】本発明に係るＮＯｘ吸蔵還元型三元触媒を用い
た排気ガス浄化装置の墓本構成の一例を表すブロック図
である。FIG. 1 is a block diagram illustrating an example of a tombstone configuration of an exhaust gas purifying apparatus using a NOx storage reduction type three-way catalyst according to the present invention.
【図２】本発明に係るＮＯｘ吸蔵還元型三元触媒を用い
た排気ガス浄化装置のシステムの一例を表す構成図であ
る。FIG. 2 is a configuration diagram illustrating an example of a system of an exhaust gas purification device using a NOx storage reduction type three-way catalyst according to the present invention.
【図３】請求項８に係る排気ガス浄化装置の第２空燃比
フィードバック手段による制御の一例を示すフローチャ
ートである。FIG. 3 is a flowchart showing an example of control by a second air-fuel ratio feedback means of the exhaust gas purifying apparatus according to claim 8;
【図４】請求項９に係る排気ガス浄化装置の第２空燃比
フィードバック手段による制御の一例を示すフローチャ
ートである。FIG. 4 is a flowchart showing an example of control by a second air-fuel ratio feedback means of the exhaust gas purifying apparatus according to claim 9;
【図５】空燃比センサ出力とＮＯｘの脱離状態を示す図
である。FIG. 5 is a diagram showing an output of an air-fuel ratio sensor and a desorption state of NOx.
【図６】図３を実施した場合における空燃比制御の一例
を示す図である。FIG. 6 is a diagram illustrating an example of air-fuel ratio control when FIG. 3 is implemented.
【図７】セリアＣｅＯ2の量とＮＯｘの脱離状態との関
係を示す図である。FIG. 7 is a graph showing the relationship between the amount of ceria CeO 2 and the state of NOx desorption.
【図８】排気ガス温度によるＮＯｘ吸収量の変化を示す
図である。FIG. 8 is a diagram showing a change in the amount of NOx absorption depending on exhaust gas temperature.
【図９】図４を実施した場合における空燃比制御の一例
を示す図である。FIG. 9 is a diagram showing an example of air-fuel ratio control when FIG. 4 is implemented.
【図１０】図３及び図４における空燃比制御の波形を示
す図である。FIG. 10 is a diagram showing a waveform of air-fuel ratio control in FIGS. 3 and 4;
【図１１】空燃比制御の波形の一例を示す図である。FIG. 11 is a diagram illustrating an example of a waveform of air-fuel ratio control.
１ 内燃機関 ２ 三元触媒 ３ ＮＯｘ吸蔵還元型三元触媒 ４ 第１空燃比検出手段 ４ａ 第１空燃比センサ ５ 第２空燃比検出手段 ５ａ 第２空燃比センサ ６ コントロールユニット ６ａ 第１空燃比フィードバック手段 ６ｂ 第２空燃比フィードバック手段 ７ 燃料噴射弁 ８ 排気管 REFERENCE SIGNS LIST 1 internal combustion engine 2 three-way catalyst 3 NOx storage reduction three-way catalyst 4 first air-fuel ratio detecting means 4 a first air-fuel ratio sensor 5 second air-fuel ratio detecting means 5 a second air-fuel ratio sensor 6 control unit 6 a first air-fuel ratio feedback Means 6b Second air-fuel ratio feedback means 7 Fuel injection valve 8 Exhaust pipe
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 ＦＩ Ｆ０１Ｎ 3/24 Ｆ０１Ｎ 3/24 Ｒ ＺＡＢ ＺＡＢＢ 3/28 ＺＡＢ 3/28 ＺＡＢ ３０１ ３０１Ｃ Ｆ０２Ｄ 41/14 ＺＡＢ Ｆ０２Ｄ 41/14 ＺＡＢ ３１０ ３１０Ｆ ──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. 6 Identification code FI F01N 3/24 F01N 3/24 R ZAB ZABB 3/28 ZAB 3/28 ZAB 301 301C F02D 41/14 ZAB F02D 41/14 ZAB 310 310F
Claims (9)
収し、吸収したＮＯｘを理論空燃比又はリッチ雰囲気で
放出して還元処理するＮＯｘ吸蔵還元型三元触媒におい
て、 白金、パラジウム、ロジウムから成る群より選ばれた少
なくとも１種の貴金属を多孔質担体に担持した貴金属担
持粉末と、次式 ＬｎαＢＯβ・・・ （式中のＬｎは、Ｌａ、Ｃｅ、Ｎｄ及びＳｍから成る群
より選ばれた少なくとも１種、Ｂは、Ｆｅ、Ｃｏ、Ｎｉ
及びＭｎから成る群より選ばれた少なくとも１種を示
し、０＜α＜１、０＜β＜４である。）で表される複合
酸化物粉末と、 Ｍｇ、Ｃａ、Ｓｒ、Ｂａ、Ｎａ、Ｋ及びＣｓから成る群
より選ばれた少なくとも１種の金属の炭酸塩と、を含有
することを特徴とするＮＯｘ吸蔵還元型三元触媒。1. A three-way NOx storage-reduction catalyst that absorbs NOx in exhaust gas in a lean atmosphere and releases the absorbed NOx in a stoichiometric air-fuel ratio or in a rich atmosphere for reduction treatment, comprising platinum, palladium, and rhodium. A noble metal-supported powder in which at least one noble metal selected from a group is supported on a porous carrier, and the following formula: LnαBOβ (where Ln is at least one selected from the group consisting of La, Ce, Nd and Sm) One type, B is Fe, Co, Ni
And Mn, wherein 0 <α <1 and 0 <β <4. NOx characterized by containing a composite oxide powder represented by the following formula: and a carbonate of at least one metal selected from the group consisting of Mg, Ca, Sr, Ba, Na, K and Cs. Storage reduction type three-way catalyst.
より選ばれた少なくとも１種、Ｃは、Ｂａ及び／又は
Ｋ、Ｂは、Ｆｅ、Ｃｏ、Ｎｉ及びＭｎから成る群より選
ばれた少なくとも１種を示し、０＜δ＜１、０．８＜α
＜１、βは、各元素の原子価を満足する酸素量であ
る。）で表されることを特徴とする請求項１記載のＮＯ
ｘ吸蔵還元型三元触媒。2. The composite oxide powder according to the following formula (Ln 1 -δCδ) αBOβ (where Ln is at least one selected from the group consisting of La, Ce, Nd and Sm; Represents Ba and / or K and B represents at least one selected from the group consisting of Fe, Co, Ni and Mn, and 0 <δ <1, 0.8 <α
<1, β is the amount of oxygen that satisfies the valence of each element. 2. The NO according to claim 1, wherein
x Storage-reduction three-way catalyst.
／又はロジウムを多孔質担体に担持して成ることを特徴
とする請求項１又は２記載のＮＯｘ吸蔵還元型三元触
媒。3. The NOx storage reduction three-way catalyst according to claim 1, wherein the noble metal-supported powder is formed by supporting palladium and / or rhodium on a porous carrier.
孔質担体に担持して成ることを特徴とする請求項１又は
２記載のＮＯｘ吸蔵還元型三元触媒。4. The three-way NOx storage reduction catalyst according to claim 1, wherein the noble metal-supported powder is formed by supporting palladium on a porous carrier.
吸蔵還元型三元触媒とを順次配置した排気ガス浄化装置
において、 上記三元触媒が、白金、パラジウム、ロジウムから成る
群より選ばれた少なくとも１種を含有し、且つこの三元
触媒に含まれるセリア及びセリアを含む複合酸化物の量
が触媒１リットル当たり５〜３０ｇであり、 上記ＮＯｘ吸蔵還元型三元触媒が、請求項１〜４のいず
れか１つの項に記載のＮＯｘ吸蔵還元型三元触媒である
ことを特徴とする排気ガス浄化装置。5. A three-way catalyst and NOx from an upstream side of an exhaust system.
In the exhaust gas purifying apparatus in which the storage reduction type three-way catalyst is sequentially arranged, the three-way catalyst contains at least one selected from the group consisting of platinum, palladium, and rhodium, and is included in the three-way catalyst. The amount of ceria and the composite oxide containing ceria is 5 to 30 g per liter of the catalyst, and the NOx storage reduction type three-way catalyst is the NOx storage reduction type three-way catalyst according to any one of claims 1 to 4. An exhaust gas purifying device characterized by being a raw catalyst.
論空燃比又はリッチに切り換えられた直後に、燃焼混合
気の空燃比をフィードバック制御し、上記ＮＯｘ吸蔵還
元型三元触媒より下流側における排気空燃比をリーンか
ら理論空燃比又はリッチに反転させることを特徴とする
請求項５記載の排気ガス浄化装置。6. Immediately after the target air-fuel ratio of the combustion air-fuel mixture is switched from lean to the stoichiometric air-fuel ratio or rich, the air-fuel ratio of the combustion air-fuel mixture is feedback-controlled so that the air-fuel ratio downstream of the NOx storage reduction type three-way catalyst is reduced. The exhaust gas purifying apparatus according to claim 5, wherein the exhaust air-fuel ratio is inverted from lean to a stoichiometric air-fuel ratio or rich.
側に配置されて排気空燃比を検出する第１空燃比検出手
段と、該ＮＯｘ吸蔵還元型三元触媒より下流側に配置さ
れて排気空燃比を検出する第２空燃比検出手段とを備
え、 更に、通常状態において、上記第１空燃比検出手段で検
出される排気空燃比に基づき燃焼混合気の空燃比を目標
空燃比にフィードバック制御する第１空燃比フィードバ
ック手段と、燃焼混合気の目標空燃比がリーンから理論
空燃比又はリッチに切り換えられた直後において、上記
第２空燃比検出手段で検出される排気空燃比に基づき燃
焼混合気の空燃比を目標空燃比にフィードバック制御す
る第２空燃比フィードバック手段とを付加して成ること
を特徴とする請求項５又は６記載の排気ガス浄化装置。7. A first air-fuel ratio detecting means disposed upstream of the NOx storage reduction type three-way catalyst to detect an exhaust air-fuel ratio, and an exhaust gas disposed downstream of the NOx storage-reduction type three-way catalyst. A second air-fuel ratio detecting means for detecting an air-fuel ratio, and further comprising, in a normal state, a feedback control of an air-fuel ratio of the combustion mixture to a target air-fuel ratio based on the exhaust air-fuel ratio detected by the first air-fuel ratio detecting means. The first air-fuel ratio feedback means and the combustion air-fuel ratio based on the exhaust air-fuel ratio detected by the second air-fuel ratio detection means immediately after the target air-fuel ratio of the combustion air-fuel mixture is switched from lean to the stoichiometric air-fuel ratio or rich. 7. The exhaust gas purifying apparatus according to claim 5, further comprising second air-fuel ratio feedback means for performing feedback control of the air-fuel ratio of the air-fuel ratio to the target air-fuel ratio.
燃焼混合気の目標空燃比がリーンから理論空燃比又はリ
ッチに切り換えられた直後において、上記第２空燃比検
出手段の出力と上記第１空燃比検出手段の出力とが等し
くなるまでフィードバック制御を行うことを特徴とする
請求項６又は７記載の排気ガス浄化装置。8. The second air-fuel ratio feedback means,
Immediately after the target air-fuel ratio of the combustion mixture is switched from lean to the stoichiometric air-fuel ratio or rich, feedback control is performed until the output of the second air-fuel ratio detecting means and the output of the first air-fuel ratio detecting means become equal. The exhaust gas purifying apparatus according to claim 6 or 7, wherein:
燃焼混合気の目標空燃比がリーンから理論空燃比又はリ
ッチに切り換えられた直後において、上記第１空燃比検
出手段の出力と上記第２空燃比検出手段の出力との比が
所定値になるまでフィードバック制御を行うことを特徴
とする請求項６又は７記載の排気ガス浄化装置。9. The second air-fuel ratio feedback means,
Immediately after the target air-fuel ratio of the combustion mixture is switched from lean to the stoichiometric air-fuel ratio or rich, until the ratio between the output of the first air-fuel ratio detecting means and the output of the second air-fuel ratio detecting means reaches a predetermined value. The exhaust gas purifying apparatus according to claim 6, wherein feedback control is performed.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP05413898A JP4450396B2 (en) | 1997-10-08 | 1998-02-20 | Exhaust gas purification device using NOx occlusion reduction type three-way catalyst |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP9-290539 | 1997-10-08 | ||
| JP29053997 | 1997-10-08 | ||
| JP05413898A JP4450396B2 (en) | 1997-10-08 | 1998-02-20 | Exhaust gas purification device using NOx occlusion reduction type three-way catalyst |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH11169670A true JPH11169670A (en) | 1999-06-29 |
| JP4450396B2 JP4450396B2 (en) | 2010-04-14 |
Family
ID=26394872
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP05413898A Expired - Fee Related JP4450396B2 (en) | 1997-10-08 | 1998-02-20 | Exhaust gas purification device using NOx occlusion reduction type three-way catalyst |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP4450396B2 (en) |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6455463B1 (en) | 2001-03-13 | 2002-09-24 | Delphi Technologies, Inc. | Alkaline earth/transition metal lean NOx catalyst |
| JP2003088759A (en) * | 2001-09-18 | 2003-03-25 | Mitsubishi Paper Mills Ltd | Low temperature oxidation catalyst filter |
| US6576587B2 (en) | 2001-03-13 | 2003-06-10 | Delphi Technologies, Inc. | High surface area lean NOx catalyst |
| US6624113B2 (en) | 2001-03-13 | 2003-09-23 | Delphi Technologies, Inc. | Alkali metal/alkaline earth lean NOx catalyst |
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| US6670296B2 (en) | 2001-01-11 | 2003-12-30 | Delphi Technologies, Inc. | Alumina/zeolite lean NOx catalyst |
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| US6864213B2 (en) | 2001-03-13 | 2005-03-08 | Delphi Technologies, Inc. | Alkaline earth / rare earth lean NOx catalyst |
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| EP1354620B1 (en) * | 2000-09-07 | 2008-07-09 | Honda Giken Kogyo Kabushiki Kaisha | Device for clarifying exhaust gas from internal combustion engine |
| EP1354620A1 (en) * | 2000-09-07 | 2003-10-22 | Honda Giken Kogyo Kabushiki Kaisha | Device for clarifying exhaust gas from internal combustion engine |
| US6670296B2 (en) | 2001-01-11 | 2003-12-30 | Delphi Technologies, Inc. | Alumina/zeolite lean NOx catalyst |
| US6576587B2 (en) | 2001-03-13 | 2003-06-10 | Delphi Technologies, Inc. | High surface area lean NOx catalyst |
| US6624113B2 (en) | 2001-03-13 | 2003-09-23 | Delphi Technologies, Inc. | Alkali metal/alkaline earth lean NOx catalyst |
| US6455463B1 (en) | 2001-03-13 | 2002-09-24 | Delphi Technologies, Inc. | Alkaline earth/transition metal lean NOx catalyst |
| US6864213B2 (en) | 2001-03-13 | 2005-03-08 | Delphi Technologies, Inc. | Alkaline earth / rare earth lean NOx catalyst |
| JP2003088759A (en) * | 2001-09-18 | 2003-03-25 | Mitsubishi Paper Mills Ltd | Low temperature oxidation catalyst filter |
| WO2004097200A1 (en) * | 2003-04-30 | 2004-11-11 | Hitachi, Ltd. | Internal combustin engine control device |
| US7246486B2 (en) | 2003-04-30 | 2007-07-24 | Hitachi, Ltd. | Combination of selected opioids with other active substances for use in the therapy of urinary incontinence |
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| WO2005090765A1 (en) * | 2004-03-24 | 2005-09-29 | Toyota Jidosha Kabushiki Kaisha | Internal combustion engine air/fuel ratio controller |
| KR101361458B1 (en) * | 2011-11-29 | 2014-02-12 | 현대자동차주식회사 | Construction Method of TWC Producing Ammonia for Passive Ammonia SCR Technology and the TWC thereof |
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