JPH057066B2 - - Google Patents
Info
- Publication number
- JPH057066B2 JPH057066B2 JP60021207A JP2120785A JPH057066B2 JP H057066 B2 JPH057066 B2 JP H057066B2 JP 60021207 A JP60021207 A JP 60021207A JP 2120785 A JP2120785 A JP 2120785A JP H057066 B2 JPH057066 B2 JP H057066B2
- Authority
- JP
- Japan
- Prior art keywords
- catalyst
- weight
- oxide
- carrier
- exhaust gas
- 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.)
- Expired - Lifetime
Links
- 239000003054 catalyst Substances 0.000 claims description 60
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical group [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 37
- MRELNEQAGSRDBK-UHFFFAOYSA-N lanthanum(3+);oxygen(2-) Chemical compound [O-2].[O-2].[O-2].[La+3].[La+3] MRELNEQAGSRDBK-UHFFFAOYSA-N 0.000 claims description 29
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims description 21
- 235000011941 Tilia x europaea Nutrition 0.000 claims description 21
- 150000004645 aluminates Chemical class 0.000 claims description 21
- 239000004571 lime Substances 0.000 claims description 21
- QVQLCTNNEUAWMS-UHFFFAOYSA-N barium oxide Chemical compound [Ba]=O QVQLCTNNEUAWMS-UHFFFAOYSA-N 0.000 claims description 20
- 238000000746 purification Methods 0.000 claims description 18
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 11
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 claims description 9
- 229910000420 cerium oxide Inorganic materials 0.000 claims description 7
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 claims description 7
- 239000000126 substance Substances 0.000 claims description 6
- AYJRCSIUFZENHW-DEQYMQKBSA-L barium(2+);oxomethanediolate Chemical compound [Ba+2].[O-][14C]([O-])=O AYJRCSIUFZENHW-DEQYMQKBSA-L 0.000 claims description 5
- 239000011230 binding agent Substances 0.000 claims description 4
- 239000003779 heat-resistant material Substances 0.000 claims 1
- KDLHZDBZIXYQEI-UHFFFAOYSA-N palladium Substances [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 17
- 229910052697 platinum Inorganic materials 0.000 description 17
- 229910052763 palladium Inorganic materials 0.000 description 11
- 239000010948 rhodium Substances 0.000 description 11
- 230000003197 catalytic effect Effects 0.000 description 10
- 239000007789 gas Substances 0.000 description 10
- 230000000694 effects Effects 0.000 description 9
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 9
- 239000000463 material Substances 0.000 description 8
- AYJRCSIUFZENHW-UHFFFAOYSA-L barium carbonate Chemical compound [Ba+2].[O-]C([O-])=O AYJRCSIUFZENHW-UHFFFAOYSA-L 0.000 description 7
- 239000000446 fuel Substances 0.000 description 7
- 238000000034 method Methods 0.000 description 7
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 6
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 6
- 229910052703 rhodium Inorganic materials 0.000 description 6
- 210000004027 cell Anatomy 0.000 description 5
- 229910052751 metal Inorganic materials 0.000 description 5
- 239000002184 metal Substances 0.000 description 5
- MHOVAHRLVXNVSD-UHFFFAOYSA-N rhodium atom Chemical compound [Rh] MHOVAHRLVXNVSD-UHFFFAOYSA-N 0.000 description 5
- 238000004901 spalling Methods 0.000 description 5
- 229910052878 cordierite Inorganic materials 0.000 description 4
- 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 4
- 229910052707 ruthenium Inorganic materials 0.000 description 4
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 230000007423 decrease Effects 0.000 description 3
- 230000006866 deterioration Effects 0.000 description 3
- 230000006872 improvement Effects 0.000 description 3
- 229910052746 lanthanum Inorganic materials 0.000 description 3
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 description 3
- 229910044991 metal oxide Inorganic materials 0.000 description 3
- 150000004706 metal oxides Chemical class 0.000 description 3
- 150000002823 nitrates Chemical class 0.000 description 3
- -1 platinum group metals Chemical class 0.000 description 3
- 239000000377 silicon dioxide Substances 0.000 description 3
- 238000005245 sintering Methods 0.000 description 3
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 2
- CPLXHLVBOLITMK-UHFFFAOYSA-N Magnesium oxide Chemical compound [Mg]=O CPLXHLVBOLITMK-UHFFFAOYSA-N 0.000 description 2
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 2
- DVARTQFDIMZBAA-UHFFFAOYSA-O ammonium nitrate Chemical class [NH4+].[O-][N+]([O-])=O DVARTQFDIMZBAA-UHFFFAOYSA-O 0.000 description 2
- BFNBIHQBYMNNAN-UHFFFAOYSA-N ammonium sulfate Chemical class N.N.OS(O)(=O)=O BFNBIHQBYMNNAN-UHFFFAOYSA-N 0.000 description 2
- 235000011130 ammonium sulphate Nutrition 0.000 description 2
- 150000001553 barium compounds Chemical class 0.000 description 2
- 229910002091 carbon monoxide Inorganic materials 0.000 description 2
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 2
- 210000002421 cell wall Anatomy 0.000 description 2
- 150000001805 chlorine compounds Chemical class 0.000 description 2
- 239000003426 co-catalyst Substances 0.000 description 2
- KZHJGOXRZJKJNY-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Si]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O.O=[Al]O[Al]=O KZHJGOXRZJKJNY-UHFFFAOYSA-N 0.000 description 2
- 150000002430 hydrocarbons Chemical class 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 229910052863 mullite Inorganic materials 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 230000008569 process Effects 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 239000007787 solid Substances 0.000 description 2
- 150000003467 sulfuric acid derivatives Chemical class 0.000 description 2
- 229910052719 titanium Inorganic materials 0.000 description 2
- 239000010936 titanium Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- QTBSBXVTEAMEQO-UHFFFAOYSA-M Acetate Chemical compound CC([O-])=O QTBSBXVTEAMEQO-UHFFFAOYSA-M 0.000 description 1
- 229910000873 Beta-alumina solid electrolyte Inorganic materials 0.000 description 1
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-M Chloride anion Chemical compound [Cl-] VEXZGXHMUGYJMC-UHFFFAOYSA-M 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- MUBZPKHOEPUJKR-UHFFFAOYSA-N Oxalic acid Chemical compound OC(=O)C(O)=O MUBZPKHOEPUJKR-UHFFFAOYSA-N 0.000 description 1
- 150000001242 acetic acid derivatives Chemical class 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 150000001785 cerium compounds Chemical class 0.000 description 1
- 229910052804 chromium Inorganic materials 0.000 description 1
- 239000011651 chromium Substances 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 239000011247 coating layer Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 229910052593 corundum Inorganic materials 0.000 description 1
- 239000010431 corundum Substances 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000006073 displacement reaction Methods 0.000 description 1
- 229910000514 dolomite Inorganic materials 0.000 description 1
- 239000010459 dolomite Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 239000008187 granular material Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- XLYOFNOQVPJJNP-UHFFFAOYSA-M hydroxide Chemical compound [OH-] XLYOFNOQVPJJNP-UHFFFAOYSA-M 0.000 description 1
- 150000004679 hydroxides Chemical class 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 150000002604 lanthanum compounds Chemical class 0.000 description 1
- FYDKNKUEBJQCCN-UHFFFAOYSA-N lanthanum(3+);trinitrate Chemical compound [La+3].[O-][N+]([O-])=O.[O-][N+]([O-])=O.[O-][N+]([O-])=O FYDKNKUEBJQCCN-UHFFFAOYSA-N 0.000 description 1
- 239000000395 magnesium oxide Substances 0.000 description 1
- 230000010534 mechanism of action Effects 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 150000003891 oxalate salts Chemical class 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 238000011056 performance test Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- IKGXIBQEEMLURG-NVPNHPEKSA-N rutin Chemical compound O[C@@H]1[C@H](O)[C@@H](O)[C@H](C)O[C@H]1OC[C@@H]1[C@@H](O)[C@H](O)[C@@H](O)[C@H](OC=2C(C3=C(O)C=C(O)C=C3OC=2C=2C=C(O)C(O)=CC=2)=O)O1 IKGXIBQEEMLURG-NVPNHPEKSA-N 0.000 description 1
- 229910052604 silicate mineral Inorganic materials 0.000 description 1
- 229910052851 sillimanite Inorganic materials 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000001179 sorption measurement Methods 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
Description
産業上の利用分野
本発明は、主として内燃機関、家庭用燃焼器等
より発生する排ガス中の有害成分を浄化する触媒
体に関し、特に一酸化炭素、炭化水素を酸化し、
窒素酸化物を還元して浄化する触媒体に関する。
従来の技術
従来、この種の触媒体として、アルミン酸石灰
を主とした担体に白金族金属触媒を担持したもの
（特開昭54−35886）や触媒粒子のシンタリングを
抑制するため酸化チタンを添加したもの（特開昭
56−126447）などが知られている。
発明が解決しようとする問題点
しかしながら、前者の触媒は、触媒物質および
担体のシンタリングによる熱劣化が激しく、ま
た、後者の触媒体は、熱劣化防止についてはかな
りの改善が見られたが、低温触媒活性の向上とい
う点では不十分であつた。また、自動車排ガス浄
化用触媒などの三元触媒性能を必要とする触媒体
において、従来の触媒体では、Rhが不可欠であ
り、同時に使用するPtに対して1/5〜1/11のRhが
用いられている。一方、Rhの産出量は、白金に
比して、1/11以下であり、また価格も白金の約２
倍と高価であることより、このRhの使用量の削
減が特に強く望まれ、従来の上述した触媒体で
は、この点においても不十分なものであつた。
本発明は、以上のような従来の触媒体の問題点
を解決し、触媒体の低温触媒活性の向上を図ると
ともに、触媒使用量の削減およびそれに伴う低コ
スト化を図り、高性能かつ安価な触媒体を提供す
ることを目的とする。
問題点を解決するための手段
本発明の触媒体は、ランタン酸化物、バリウム
酸化物および炭酸バリウムよりなる群より選ばれ
る助触媒物質と、結合剤のアルミン酸石灰より構
成された担体に、白金族触媒物質を担持させたも
のである。
作 用
結合剤に用いるアルミン酸石灰は、水硬性を有
するため、従来のコージライトやムライト等の触
媒担体を製造する際に必要な焼結処理が不要であ
り、無焼結で比表用面積の大なる触媒担体を得る
ことができる。この比表面積が大なることによ
り、従来の上記焼結型担体において比表面積拡大
に必要なウオツシユコート処理が不要となる。
アルミン酸石灰は、固体塩基触媒能を有するた
め、排ガス中の有害成分、特に炭化水素化合物
（以下HCと略す）の浄化に非常に良好な活性を
示す。
アルミン酸石灰の担体中での含有量は15重量％
以上、50重量％以下である。アルミン酸石灰の含
有量が15重量％以下では十分な機械的強度が望め
ず、また50重量％を超えると耐スポーリング特性
が著しく低下する。
アルミン酸石灰は、一般式mAl2O3・nCaOで
示され、含まれるアルミナ分が50重量％以上、85
重量％以下が望ましく、特に60重量％以上、80重
量％以下が望ましい。これは、アルミン酸石灰中
に含まれるアルミナ分が50重量％未満では、触媒
体の熱劣化が著しくなり、またアルミナ分が85重
量％を超えると、アルミン酸石灰の結合力が著し
く弱くなるとともに、硬化速度が著しく早くなる
ため、ハニカム形状等の複雑な成形加工が困難と
なるためである。
ランタン酸化物は、窒素酸化物（以下NOxと
略す）の吸着能に優れ、また水素に対する親和性
も大である。このため、白金族金属のPt，Pdと
ともに用いることによつて、理論空燃比よりも燃
料の濃い側で燃焼させた場合に排ガス中に含まれ
る窒素酸化物の上記Pt，Pdによる浄化特性改善
に寄与し、この特性を著しく改善する助触媒物質
として働く。また、バリウム酸化物および炭酸バ
リウムについても同様の作用がある。
ランタン酸化物およびバリウム酸化物は、その
塩化物、水酸化物、酢酸塩、蓚酸塩、硫酸塩、硝
酸塩、炭酸塩、硫酸アンモニウム塩、硝酸アンモ
ニウム塩を出発物質とし、使用する前に焼成する
か、あるいは成形体とした後に焼成し、酸化物と
して用いる方法と、触媒担持の焼成過程で、触媒
担持と同時に前記ランタン化合物、バリウム化合
物を酸化物にする方法等がある。
ランタン酸化物、バリウム酸化物、炭酸バリウ
ムより構成される本発明の助触媒物質は、担体中
の含有量が１重量％以上、50重量％以下が望まし
い。前記含有量が１重量％未満では、前記助触媒
物質の十分な添加効果が望めず、また50重量％を
超えると、それに見合うだけの助触媒作用の増加
が望めないばかりかHC浄化能が逆に低下してく
る。
一般に、ランタン酸化物は、PtあるいはPdと
同時に用いることにより、理論空燃比より燃料比
率の高い領域で運転した場合に出す排ガス（以後
リツチ側での排ガスと記す）中に含まれるNOx
のPt，Pdによる浄化特性を著しく向上させるが、
同時に、理論空燃比より燃料希薄条件でエンジン
を運転した際発生する排ガス（以後リーン側での
排ガスと記す。）中に含まれるHC浄化能を低下
させてしまう。バリウム酸化物、炭酸塩について
も同様である。この現象は特に自動車三元用触媒
として用いる場合に場合に非常に大きな問題点で
あり、前述した従来のコージライト等の焼結型触
媒担体を用いた触媒体ではこの問題点の解決が難
しかつた。一方前述したように、本発明の触媒担
体は固体塩基触媒能を有するアルミン酸石灰を含
むため、これによるHC浄化作用によりリーン側
排ガスでも、HC浄化能の低下のない触媒体を得
ることができる。さらにランタン酸化物、バリウ
ム酸化物、バリウム炭酸塩等の助触媒物質とアル
ミン酸石灰を同時に用いることにより低温での触
媒活性が非常に改善される。さらにセリウム酸化
物あるいは酸化チタンを上記助触媒物質とともに
用いることによりさらに低温触媒活性が増大す
る。特に、セリウム酸化物は、酸素ストレージ能
を有するため、自動車用触媒として用いた場合、
そのウインドウ幅も広いものが得られ望ましいも
のである。
加熱によりセリウム酸化物となるセリウム化合
物は、その水酸化物、塩化物、酢酸塩、蓚酸塩、
硫酸塩、硝酸塩、炭酸塩、硫酸アンモニウム塩、
硝酸アンモニウム塩などがある。セリウム酸化物
の望ましい前記担体中の含有量は５重量％以上、
63重量％以下である。
酸化チタンも同様に低温触媒活性を向上させ
る。酸化チタンの作用機構は明らかではないが、
一般に、チタンを含む複合金属酸化物には、金属
酸化物半導体として知られているものがあり、本
発明においてもランタンとチタンとの金属酸化物
半導体が一部形成されることにより、これが助触
媒的に働いて触媒活性を向上させているものと考
えられる。用いる酸化チタンはアナターゼ型およ
びルチル型どちらの構造であつても良好な結果が
得られる。酸化チタンの好ましい担体中の含有量
は、２重量％以上、50重量％以下である。
本発明の前記担体の形状は粒状、ハニカム状等
の任意の形状を用いることができ、また成形方法
も、押出成形法、コルゲーテイング法等種々の方
法を用いることができる。
本発明で用いる白金族触媒物質としては、Pt，
Pd，Rh，Ruがあり、還元・分解してこれらの金
属となる白金族金属化合物を水またはアルコール
等の溶媒に溶解させて用いることができる。
なお、前記の担体は耐熱性基骨材を含むことが
望ましい。これは、触媒体の機械的強度、耐熱強
度の向上が図れるためであり、耐熱性基骨材に
は、シリカ系基骨材、シリカアルミナ系基骨材、
アルミナ系基骨材があり、鉱物として、ケイ酸塩
鉱物、ムライト、コランダム、シリマナイト、β
−アルミナ、さらにはマグネシア、クロム、ドロ
マイト、マゲクロ、クロマグ系のものを用いるこ
とができる。
実施例
以下、本発明の実施例を説明する。
〈実施例 １〜８〉
酸化ランタン（La2O3）、酸化バリウム、炭酸
バリウム、アルミン酸石灰、酸化チタン、酸化セ
リウム（CeO2）および耐熱性基骨材としてのシ
リカを第１表に示す組成で配合し、適当量の水を
加えて混練した後、セル壁厚0.25mm、セル密度
400セル／in2のハニカム形状に押出成形し、養
生・乾燥の後800℃で〓焼して担体とした。この
担体に塩化白金酸を用いて白金を担体１c.c.あたり
１mg担持して実施例１〜８の触媒体を得た。
〈比較例 １〜３〉
第１表に示す比較例１，２の組成の担体を実施
例１〜８と同様の方法により作り、これに前記実
施例と同量の白金量を担持して比較例１，２の触
媒体を得た。またアルミナ被覆層を有するコージ
ライトハニカム成形体（平均セル壁厚0.25mm、セ
ル密度400セル／in2）上に、硝酸ランタンを用い
て、その熱分解により酸化ランタンとして成形体
重量に対して２重量％となる量担持した後、白金
を前記実施例と同様にして担体１c.c.あたり１mg担
持した比較例３の触媒体を得た。
INDUSTRIAL APPLICATION FIELD The present invention relates to a catalyst body that purifies harmful components in exhaust gas mainly generated from internal combustion engines, domestic combustors, etc., and in particular, oxidizes carbon monoxide and hydrocarbons.
The present invention relates to a catalyst body that reduces and purifies nitrogen oxides. Conventional technology Conventionally, this type of catalyst has been made by supporting a platinum group metal catalyst on a carrier mainly made of lime aluminate (Japanese Patent Application Laid-Open No. 1983-35886), or by adding titanium oxide to suppress sintering of catalyst particles. Added (Tokkai Sho)
56-126447) are known. Problems to be Solved by the Invention However, the former catalyst suffers from severe thermal deterioration due to sintering of the catalyst material and carrier, and the latter catalyst shows considerable improvement in preventing thermal deterioration. The improvement in low-temperature catalyst activity was insufficient. In addition, in catalyst bodies that require three-way catalyst performance, such as catalysts for purifying automobile exhaust gas, Rh is essential in conventional catalyst bodies, and Rh is 1/5 to 1/11 of Pt used at the same time. It is used. On the other hand, the production amount of Rh is less than 1/11 that of platinum, and the price is about 2 times that of platinum.
Since Rh is twice as expensive, there is a strong desire to reduce the amount of Rh used, and the conventional catalysts described above were insufficient in this respect as well. The present invention solves the problems of conventional catalyst bodies as described above, improves the low-temperature catalytic activity of the catalyst body, and reduces the amount of catalyst used and the associated cost. The purpose is to provide a catalyst body. Means for Solving the Problems The catalyst body of the present invention has platinum added to a carrier composed of a cocatalyst material selected from the group consisting of lanthanum oxide, barium oxide and barium carbonate, and lime aluminate as a binder. It supports a group catalyst material. Function The lime aluminate used as a binder has hydraulic properties, so it does not require the sintering process that is required when manufacturing conventional catalyst supports such as cordierite and mullite. A large catalyst support can be obtained. This increase in specific surface area eliminates the need for wash coating, which is necessary for increasing the specific surface area in the conventional sintered carrier. Since lime aluminate has a solid base catalytic ability, it shows very good activity in purifying harmful components in exhaust gas, especially hydrocarbon compounds (hereinafter abbreviated as HC). The content of lime aluminate in the carrier is 15% by weight
above, and below 50% by weight. If the content of lime aluminate is less than 15% by weight, sufficient mechanical strength cannot be expected, and if it exceeds 50% by weight, the spalling resistance properties will be significantly reduced. Lime aluminate has the general formula mAl 2 O 3 nCaO, and contains 50% by weight or more of alumina, 85
It is preferably at most 60% by weight and at most 80% by weight. This is because if the alumina content in the aluminate lime is less than 50% by weight, the thermal deterioration of the catalyst will be significant, and if the alumina content exceeds 85% by weight, the binding strength of the aluminate lime will be significantly weakened. This is because the curing speed becomes extremely high, making it difficult to form complex shapes such as honeycomb shapes. Lanthanum oxide has excellent adsorption ability for nitrogen oxides (hereinafter abbreviated as NOx) and also has a high affinity for hydrogen. Therefore, by using it together with platinum group metals Pt and Pd, the above-mentioned Pt and Pd can improve the purification characteristics of nitrogen oxides contained in exhaust gas when the fuel is burnt on the richer side than the stoichiometric air-fuel ratio. It acts as a co-catalyst material that contributes and significantly improves this property. Further, barium oxide and barium carbonate have similar effects. Lanthanum oxide and barium oxide are prepared by starting from their chlorides, hydroxides, acetates, oxalates, sulfates, nitrates, carbonates, ammonium sulfates, and ammonium nitrates and calcining them before use, or There is a method in which the molded body is fired and then used as an oxide, and a method in which the lanthanum compound and barium compound are converted into oxides at the same time as the catalyst is supported in the firing process of supporting the catalyst. The content of the cocatalyst material of the present invention composed of lanthanum oxide, barium oxide, and barium carbonate in the carrier is preferably 1% by weight or more and 50% by weight or less. If the content is less than 1% by weight, a sufficient effect of the addition of the promoter substance cannot be expected, and if it exceeds 50% by weight, not only a commensurate increase in the promoter action cannot be expected, but also the HC purification ability is adversely affected. It starts to decline. In general, when used together with Pt or Pd, lanthanum oxide can reduce NOx contained in the exhaust gas (hereinafter referred to as rich side exhaust gas) produced when operating at a fuel ratio higher than the stoichiometric air-fuel ratio.
Although it significantly improves the purification properties of Pt and Pd,
At the same time, it reduces the ability to purify HC contained in the exhaust gas (hereinafter referred to as exhaust gas on the lean side) generated when the engine is operated under conditions where the fuel is leaner than the stoichiometric air-fuel ratio. The same applies to barium oxide and carbonate. This phenomenon is a very serious problem especially when used as an automobile three-way catalyst, and it is difficult to solve this problem with the catalyst body using the conventional sintered catalyst carrier such as cordierite mentioned above. Ta. On the other hand, as mentioned above, since the catalyst carrier of the present invention contains aluminate lime having solid base catalytic ability, the HC purifying effect thereof makes it possible to obtain a catalyst body without a decrease in HC purifying ability even in lean side exhaust gas. . Further, by simultaneously using cocatalyst materials such as lanthanum oxide, barium oxide, barium carbonate, and lime aluminate, the catalytic activity at low temperatures is greatly improved. Furthermore, by using cerium oxide or titanium oxide together with the above-mentioned promoter, the low-temperature catalytic activity is further increased. In particular, since cerium oxide has oxygen storage ability, when used as an automobile catalyst,
A wide window width can also be obtained, which is desirable. Cerium compounds that become cerium oxide by heating include its hydroxide, chloride, acetate, oxalate,
sulfates, nitrates, carbonates, ammonium sulfates,
Examples include ammonium nitrate salts. A desirable content of cerium oxide in the carrier is 5% by weight or more,
63% by weight or less. Titanium oxide similarly improves low temperature catalytic activity. Although the mechanism of action of titanium oxide is not clear,
In general, some composite metal oxides containing titanium are known as metal oxide semiconductors, and in the present invention, a metal oxide semiconductor of lanthanum and titanium is partially formed, so that this becomes a co-catalyst. It is thought that this function acts as a catalyst to improve the catalytic activity. Good results can be obtained regardless of whether the titanium oxide used has an anatase or rutile structure. The content of titanium oxide in the carrier is preferably 2% by weight or more and 50% by weight or less. The shape of the carrier of the present invention can be any shape such as granule or honeycomb shape, and various molding methods such as extrusion molding method and corrugating method can be used. The platinum group catalyst materials used in the present invention include Pt,
There are Pd, Rh, and Ru, and platinum group metal compounds that become these metals by reduction and decomposition can be used by dissolving them in a solvent such as water or alcohol. Note that the carrier desirably contains a heat-resistant base aggregate. This is because the mechanical strength and heat-resistant strength of the catalyst can be improved, and heat-resistant base aggregates include silica-based base aggregate, silica-alumina-based base aggregate,
There is an alumina base aggregate, and the minerals include silicate minerals, mullite, corundum, sillimanite, β
- Alumina, as well as magnesia, chromium, dolomite, magne black, and chromag-based materials can be used. Examples Examples of the present invention will be described below. <Examples 1 to 8> Lanthanum oxide (La 2 O 3 ), barium oxide, barium carbonate, lime aluminate, titanium oxide, cerium oxide (CeO 2 ), and silica as a heat-resistant base aggregate are shown in Table 1. After mixing with the following composition and adding an appropriate amount of water, the cell wall thickness is 0.25 mm and the cell density is 0.25 mm.
It was extruded into a honeycomb shape of 400 cells/in 2 , cured and dried, and then baked at 800°C to form a carrier. The catalysts of Examples 1 to 8 were obtained by supporting 1 mg of platinum per 1 c.c. of the carrier using chloroplatinic acid. <Comparative Examples 1 to 3> Supports having the compositions of Comparative Examples 1 and 2 shown in Table 1 were prepared in the same manner as in Examples 1 to 8, and the same amount of platinum as in the above Examples was supported for comparison. Catalyst bodies of Examples 1 and 2 were obtained. In addition, lanthanum nitrate was used on a cordierite honeycomb molded body (average cell wall thickness 0.25 mm, cell density 400 cells/in 2 ) having an alumina coating layer, and by thermal decomposition it was converted into lanthanum oxide at a rate of 2% of the molded weight. After supporting the catalyst in an amount equal to % by weight, a catalyst of Comparative Example 3 was obtained in which 1 mg of platinum was supported per 1 c.c. of the support in the same manner as in the above example.
【表】【table】
【表】
〈実施例 ９〜11〉
実施例１の担体に用いたハニカム成形体に、白
金、パラジウム、ロジウムまたはルテニウムを第
２表に示す量だけ担持した実施例９〜11の触媒体
を調製した。それぞれの白金族金属の担持には、
白金、パラジウムは塩化物を、ロジウム、ルテニ
ウムには硝酸塩を用い、これを熱分解して白金族
金属として用いた。
以上で調製した各種の触媒体について、次に示
す触媒性能試験をした。すなわち、2000c.c.の排気
量のエンジンを用い、1800rpmの回転数でトルク
を調整し、触媒入口温度が500℃±10℃で、触媒
に対する空間速度を50000hr-1として、エンジン
を運転した。この条件で、空燃比（Ａ／Ｆと以下
略す）を14.0〜15.0まで変化させ、それぞれの
Ａ／Ｆ値での三元成分（一酸化炭素（以下COと
記す），HC，NOx）の浄化能を測定した。第２
表に、それぞれの触媒体について、リツチ側
（14.4A／Ｆ）でのNOx浄化率およびリーン側
（14.8A／Ｆ）でのHC，CO浄化率を示す。
次に、O2１％、CO1000ppm、水分10％の試験
ガスを調製し、これを、200℃から400℃まで種々
の温度に変化させた触媒体に、空間速度
50000hr-1で流し、その時のCO浄化率が50％とな
る触媒体温度をT50（℃）として測定した。その
結果も第２表に示す。[Table] <Examples 9 to 11> Catalyst bodies of Examples 9 to 11 were prepared in which the honeycomb molded body used as the carrier in Example 1 supported platinum, palladium, rhodium, or ruthenium in the amount shown in Table 2. did. For supporting each platinum group metal,
Chlorides were used for platinum and palladium, and nitrates were used for rhodium and ruthenium, which were thermally decomposed and used as platinum group metals. The various catalyst bodies prepared above were subjected to the following catalytic performance tests. That is, an engine with a displacement of 2000 c.c. was used, the torque was adjusted at a rotation speed of 1800 rpm, the catalyst inlet temperature was 500°C ± 10°C, and the engine was operated with a space velocity relative to the catalyst of 50000 hr -1 . Under these conditions, the air-fuel ratio (hereinafter abbreviated as A/F) was varied from 14.0 to 15.0, and the ternary components (carbon monoxide (hereinafter referred to as CO), HC, NOx) were purified at each A/F value. The performance was measured. Second
The table shows the NOx purification rate on the rich side (14.4 A/F) and the HC and CO purification rate on the lean side (14.8 A/F) for each catalyst body. Next, a test gas containing 1% O 2 , 1000 ppm CO, and 10% moisture was prepared, and this was applied to a catalyst body whose temperature was varied from 200°C to 400°C at various space velocities.
The catalyst temperature at which the CO purification rate was 50% at that time was measured as T50 (°C). The results are also shown in Table 2.
【表】【table】
【表】
第２表より明らかなように、本発明のアルミン
酸石灰とランタン酸化物、前記バリウム化合物を
用いた触媒体は、従来のアルミン酸石灰を用いた
触媒体比較（例１，２）に比べ、リツチ側での白
金によるNOx浄化能を著しく高め、従来この領
域でのNOx浄化能をロジウムに頼つていたもの
を、白金、パラジウムで多くを代替することが可
能であると考えられる。パラジウムについても同
様の浄化性能の向上が得られた。また本発明のラ
ンタン、バリウムの酸化物および炭酸バリウム
と、酸化チタンあるいは酸化セリウムを同時に用
いることにより、より触媒体の触媒活性を向上す
ることができCOに対する活性化温度を30〜40℃
低減することが可能であつた。
また従来のコージライト担体を用いランタンで
被覆した触媒体が、リーン側でのHC，COに対す
る触媒活性が低いのに比べ、本発明のアルミン酸
石灰を用いた触媒体は、高い活性を示した。
また、白金および／あるいはパラジウムととも
にロジウムあるいはルテニウムを用いることによ
り、さらに良好な触媒体を得ることができた。
〈実施例 12〜22〉
アルミン酸石灰の担体中の含有量を、第３表に
示すように種々変化させ、前記実施例１と同様に
成形体を調製し、触媒物質を担持しない状態で、
セル方向の圧縮強度（Ａ軸圧縮強度）および耐ス
ポーリング性試験をした。耐スポーリング試験
は、500℃より50℃おきに900℃まで行ない、成形
体に最初に亀裂が入つた時の炉内温度を耐スポー
リング温度（℃）とした。結果を第３表に示す。[Table] As is clear from Table 2, the catalyst body using lime aluminate, lanthanum oxide, and the barium compound of the present invention is compared with the catalyst body using conventional lime aluminate (Examples 1 and 2). Compared to this, the NOx purification ability of platinum on the rich side has been significantly improved, and it is thought that it is possible to replace much of the NOx purification ability in this area with platinum and palladium, which previously relied on rhodium. . A similar improvement in purification performance was obtained with palladium. Furthermore, by simultaneously using lanthanum, barium oxide, and barium carbonate of the present invention, and titanium oxide or cerium oxide, the catalytic activity of the catalyst can be further improved, and the activation temperature for CO can be lowered to 30 to 40°C.
It was possible to reduce this. Furthermore, compared to the conventional catalyst body using a cordierite carrier and coated with lanthanum, which had low catalytic activity against HC and CO on the lean side, the catalyst body using lime aluminate of the present invention showed high activity. . Further, by using rhodium or ruthenium together with platinum and/or palladium, an even better catalyst could be obtained. <Examples 12 to 22> The content of lime aluminate in the carrier was varied as shown in Table 3, molded bodies were prepared in the same manner as in Example 1, and without supporting a catalyst substance,
Compressive strength in the cell direction (A-axis compressive strength) and spalling resistance tests were conducted. The spalling resistance test was conducted from 500°C to 900°C at 50°C intervals, and the temperature in the furnace when the molded article first cracked was taken as the spalling resistance temperature (°C). The results are shown in Table 3.
【表】
第３表より明らかなように、アルミン酸石灰の
成形体中での含有量が15重量％未満では圧縮強度
が低く、また50重量％を超えると耐スポーリング
性が低下した。
〈実施例 23〉
成形体中のアルミン酸石灰の含有量を30重量％
とし、酸化ランタンの含有量を0.1〜70重量％ま
で変化させ、残部をシリカとした種々の成形体を
実施例１と同様にして調製し、それぞれに白金を
成形体１c.c.あたり１mg担持した。それぞれについ
て、実施例１に対して行なつたと同様の14.4A／
ＦにおけるNOx浄化能、14.8A／ＦにおけるHC
浄化能を試験した。その結果を図に示した。
図より明らかなように、酸化ランタンの十分な
添加効果が得られるのは１重量％以上からであ
り、また50重量％を超えるとリーン側でのHC浄
化率が低下する。したがつて、ランタン酸化物の
望ましい添加量は、１重量％以上50重量％以下で
ある。
発明の効果
以上のように、本発明によれば、低温での触媒
活性が向上するとともに、自動車用三元触媒に用
いた場合、リツチ側での白金、パラジウムの
NOx浄化能を著しく高めるため、ロジウム必要
量の低減により、低コスト化を図ることができ
る。[Table] As is clear from Table 3, when the content of lime aluminate in the compact was less than 15% by weight, the compressive strength was low, and when it exceeded 50% by weight, the spalling resistance was reduced. <Example 23> The content of lime aluminate in the molded body is 30% by weight
Various molded bodies were prepared in the same manner as in Example 1, with the content of lanthanum oxide varied from 0.1 to 70% by weight and the balance being silica, and each of them was loaded with 1 mg of platinum per c.c. did. For each, the same 14.4A/
NOx purification ability at F, HC at 14.8A/F
Purification ability was tested. The results are shown in the figure. As is clear from the figure, a sufficient addition effect of lanthanum oxide can be obtained from 1% by weight or more, and if it exceeds 50% by weight, the HC purification rate on the lean side decreases. Therefore, the desirable addition amount of lanthanum oxide is 1% by weight or more and 50% by weight or less. Effects of the Invention As described above, according to the present invention, the catalyst activity at low temperatures is improved, and when used in a three-way catalyst for automobiles, platinum and palladium are
Since the NOx purification ability is significantly increased, the amount of rhodium required can be reduced, resulting in lower costs.
図は担体中に含まれる酸化ランタンの含有量に
対するNOxおよびHC浄化率を示した図である。
The figure shows the NOx and HC purification rates relative to the lanthanum oxide content contained in the carrier.
Claims (1)
バリウムよりなる群より選ばれた１種以上の助触
媒物質と、結合剤のアルミン酸石灰と、必要に応
じて含有させた耐熱性基骨材とより構成された担
体に、白金族触媒物質を担持したことを特徴とす
る排ガス浄化用触媒体。 ２ 前記担体の助触媒物質含有量が、1.0重量％
以上、50重量％以下である特許請求の範囲第１項
記載の排ガス浄化用触媒体。 ３ 前記担体中のアルミン酸石灰含有量が15重量
％以上、50重量％以下である特許請求の範囲第１
項記載の排ガス浄化用触媒体。 ４ ランタン酸化物、バリウム酸化物および炭酸
バリウムよりなる群より選ばれる１種以上の助触
媒物質と、結合剤のアルミン酸石灰と、セリウム
酸化物および酸化チタンの少なくとも一方と、必
要に応じて含有させた耐熱性基骨材とより構成さ
れた担体に、白金族触媒物質を担持したことを特
徴とする排ガス浄化用触媒体。[Scope of Claims] 1. A heat-resistant material containing one or more promoter substances selected from the group consisting of lanthanum oxide, barium oxide, and barium carbonate, lime aluminate as a binder, and as necessary. A catalyst body for exhaust gas purification, characterized in that a platinum group catalyst substance is supported on a carrier composed of a base aggregate. 2 The promoter content of the carrier is 1.0% by weight
The catalyst body for exhaust gas purification according to claim 1, wherein the amount is 50% by weight or less. 3. Claim 1, wherein the content of lime aluminate in the carrier is 15% by weight or more and 50% by weight or less.
Catalyst body for exhaust gas purification as described in . 4. Contains one or more promoter substances selected from the group consisting of lanthanum oxide, barium oxide, and barium carbonate, lime aluminate as a binder, and at least one of cerium oxide and titanium oxide, as necessary. A catalyst body for exhaust gas purification, characterized in that a platinum group catalyst substance is supported on a carrier made of a heat-resistant base aggregate.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60021207A JPS61181538A (en) | 1985-02-06 | 1985-02-06 | Catalyst for purifying exhaust gas |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60021207A JPS61181538A (en) | 1985-02-06 | 1985-02-06 | Catalyst for purifying exhaust gas |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61181538A JPS61181538A (en) | 1986-08-14 |
| JPH057066B2 true JPH057066B2 (en) | 1993-01-28 |
Family
ID=12048542
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP60021207A Granted JPS61181538A (en) | 1985-02-06 | 1985-02-06 | Catalyst for purifying exhaust gas |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS61181538A (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1993007363A1 (en) * | 1991-10-03 | 1993-04-15 | Toyota Jidosha Kabushiki Kaisha | Device for purifying exhaust of internal combustion engine |
| JP3311012B2 (en) * | 1992-03-23 | 2002-08-05 | 株式会社豊田中央研究所 | Exhaust gas purification catalyst and exhaust gas purification method |
| JP2605553B2 (en) * | 1992-08-04 | 1997-04-30 | トヨタ自動車株式会社 | Exhaust gas purification device for internal combustion engine |
| JP3303486B2 (en) * | 1993-12-17 | 2002-07-22 | トヨタ自動車株式会社 | Method for producing exhaust gas purifying catalyst |
| FR2802917B1 (en) * | 1999-12-28 | 2002-06-14 | Rhodia Terres Rares | COMPOSITION BASED ON LANTHANUM OXIDE, IN EXTRUDED FORM, ITS PREPARATION METHOD AND ITS USE IN CATALYSIS |
-
1985
- 1985-02-06 JP JP60021207A patent/JPS61181538A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61181538A (en) | 1986-08-14 |
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