JPH0424099B2 - - Google Patents
Info
- Publication number
- JPH0424099B2 JPH0424099B2 JP58042337A JP4233783A JPH0424099B2 JP H0424099 B2 JPH0424099 B2 JP H0424099B2 JP 58042337 A JP58042337 A JP 58042337A JP 4233783 A JP4233783 A JP 4233783A JP H0424099 B2 JPH0424099 B2 JP H0424099B2
- Authority
- JP
- Japan
- Prior art keywords
- combustion
- metal
- catalyst
- carrier
- fine particles
- 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 45
- 238000002485 combustion reaction Methods 0.000 claims description 38
- 229910052751 metal Inorganic materials 0.000 claims description 33
- 239000002184 metal Substances 0.000 claims description 33
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 28
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 19
- 239000010419 fine particle Substances 0.000 claims description 14
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims description 13
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 claims description 10
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 claims description 9
- 229910052684 Cerium Inorganic materials 0.000 claims description 7
- 229910052746 lanthanum Inorganic materials 0.000 claims description 7
- 239000011247 coating layer Substances 0.000 claims description 6
- 239000011651 chromium Substances 0.000 claims description 5
- 229910052697 platinum Inorganic materials 0.000 claims description 5
- 229910052712 strontium Inorganic materials 0.000 claims description 5
- GWXLDORMOJMVQZ-UHFFFAOYSA-N cerium Chemical compound [Ce] GWXLDORMOJMVQZ-UHFFFAOYSA-N 0.000 claims description 4
- 229910052804 chromium Inorganic materials 0.000 claims description 4
- FZLIPJUXYLNCLC-UHFFFAOYSA-N lanthanum atom Chemical compound [La] FZLIPJUXYLNCLC-UHFFFAOYSA-N 0.000 claims description 4
- 229910052759 nickel Inorganic materials 0.000 claims description 4
- 229910052763 palladium Inorganic materials 0.000 claims description 4
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 claims description 2
- 229910017052 cobalt Inorganic materials 0.000 claims description 2
- 239000010941 cobalt Substances 0.000 claims description 2
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 2
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 claims description 2
- 229910000510 noble metal Inorganic materials 0.000 description 16
- 230000000694 effects Effects 0.000 description 10
- 239000010410 layer Substances 0.000 description 10
- 239000000203 mixture Substances 0.000 description 9
- 239000008199 coating composition Substances 0.000 description 8
- 150000002739 metals Chemical class 0.000 description 7
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 7
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 6
- 239000002923 metal particle Substances 0.000 description 6
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 6
- 239000007787 solid Substances 0.000 description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 6
- 238000010438 heat treatment Methods 0.000 description 5
- 239000007864 aqueous solution Substances 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 4
- 230000007423 decrease Effects 0.000 description 4
- 238000001035 drying Methods 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- 229910001111 Fine metal Inorganic materials 0.000 description 3
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 3
- 239000002253 acid Substances 0.000 description 3
- 229910052878 cordierite Inorganic materials 0.000 description 3
- 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 3
- 239000006185 dispersion Substances 0.000 description 3
- 239000000446 fuel Substances 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 230000014759 maintenance of location Effects 0.000 description 3
- PIBWKRNGBLPSSY-UHFFFAOYSA-L palladium(II) chloride Chemical compound Cl[Pd]Cl PIBWKRNGBLPSSY-UHFFFAOYSA-L 0.000 description 3
- 150000003839 salts Chemical class 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 238000012546 transfer Methods 0.000 description 3
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- MCMNRKCIXSYSNV-UHFFFAOYSA-N Zirconium dioxide Chemical compound O=[Zr]=O MCMNRKCIXSYSNV-UHFFFAOYSA-N 0.000 description 2
- 229910052918 calcium silicate Inorganic materials 0.000 description 2
- 239000000378 calcium silicate Substances 0.000 description 2
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 description 2
- 238000007084 catalytic combustion reaction Methods 0.000 description 2
- 230000003197 catalytic effect Effects 0.000 description 2
- SQKWGPOIVHMUNF-UHFFFAOYSA-K cerium(3+);trichloride;hexahydrate Chemical compound O.O.O.O.O.O.[Cl-].[Cl-].[Cl-].[Ce+3] SQKWGPOIVHMUNF-UHFFFAOYSA-K 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 238000003912 environmental pollution Methods 0.000 description 2
- 239000007789 gas Substances 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 239000010970 precious metal Substances 0.000 description 2
- FDFPDGIMPRFRJP-UHFFFAOYSA-K trichlorolanthanum;heptahydrate Chemical compound O.O.O.O.O.O.O.[Cl-].[Cl-].[Cl-].[La+3] FDFPDGIMPRFRJP-UHFFFAOYSA-K 0.000 description 2
- BPQQTUXANYXVAA-UHFFFAOYSA-N Orthosilicate Chemical compound [O-][Si]([O-])([O-])[O-] BPQQTUXANYXVAA-UHFFFAOYSA-N 0.000 description 1
- 238000005054 agglomeration Methods 0.000 description 1
- 230000002776 aggregation Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000001354 calcination Methods 0.000 description 1
- 239000000969 carrier Substances 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000000567 combustion gas Substances 0.000 description 1
- 238000009841 combustion method Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 229910052593 corundum Inorganic materials 0.000 description 1
- 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 1
- 238000007598 dipping method Methods 0.000 description 1
- 239000002612 dispersion medium Substances 0.000 description 1
- 238000010304 firing Methods 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 229910001510 metal chloride Inorganic materials 0.000 description 1
- 229910052863 mullite Inorganic materials 0.000 description 1
- 150000004767 nitrides Chemical class 0.000 description 1
- 230000001590 oxidative effect Effects 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 239000002244 precipitate Substances 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 229910052596 spinel Inorganic materials 0.000 description 1
- 239000011029 spinel Substances 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
- 229910001845 yogo sapphire Inorganic materials 0.000 description 1
Landscapes
- Gas Burners (AREA)
- Catalysts (AREA)
Description
［発明の技術分野］
本発明は、高温燃焼触媒に関し、更に詳しくは
約800℃〜1500℃の温度範囲において、高活性及
び長寿命を有する高温燃焼触媒に関する。
［発明の技術的背景とその問題点］
近年、石油資源等の枯渇化に伴い、エネルギー
資源を効率的に使用するため、例えば、ガスター
ビン等においては、できるだけ高温において燃料
を燃焼させることが望まれている。
しかしながら、従来は、燃料と空気の混合物
を、スパークプラグ等を用いて着火燃焼せしめる
方法であるため、燃焼器内において、部分的に
2000℃を超える高温部が存在する。そして、この
高温部において、窒素酸化物（NOx）が多量に
生成し、環境汚染等の問題を生ずることが知られ
ている。
このような問題を解決するために、触媒を用い
て燃料と空気の混合物を燃焼せしめる触媒燃焼方
式が提案されている。この燃焼方式によれば、均
一燃焼が可能であり、且つ、NOxが生成しない
上限温度である1500℃程度まで、燃焼温度を高め
ることができる。
現在、触媒燃焼方式に使用される触媒としては
白金（Pt）糸の貴金属触媒が知られている。こ
のような貴金属系燃焼触媒は、例えば、第１図に
示したように、一定の機械的強度を有する担体１
上に、活性担体としてγ−アルミナ（γ−
Al2O3）２を塗布し、更に、浸漬法により、貴金
属３を担持させたものである。
しかしながら、上記した貴金属系燃焼触媒は、
その耐熱温度が通常600℃と言われており、それ
以上の温度域では触媒活性が急速に低下し、使用
することができないという問題点を有している。
600℃以上の温度において、触媒活性が急速に
低下する原因は、次のように考えることができ
る。先ず、第１に、担体表面の貴金属粒子が熱移
動により凝集して粗大化するため、触媒表面積が
減少し、燃焼性能が低下する。そして、第２にγ
−Al2O3が1000℃付近からそれ以上の温度におい
て、α−Al2O3に相転移するため、Al2O3相内に
おいて或いはAl2O3と担体との間においてクラツ
クが生じAl2O3相が触媒金属と共に剥離脱落する
ことに起因すると考えられる。
そこで、貴金属系燃焼触媒の耐熱性を向上せし
めるために、γ−Al2O3相を改良し、γ−Al2O3
相上のPt粒子をAl2O3に強く吸着させて熱移動に
よる凝集を防止すると共に、γ−Al2O3相のα化
を防止してクラツクの発生を防ぐことが試みられ
ている。
その結果、γ−Al2O3相への金属の添加により
自動車触媒の一部においては800℃前後まで使用
できる耐熱性燃焼触媒が開発されている。
［発明の目的］
本発明の目的は、約800〜1500℃の温度範囲に
おいても高活性及び長寿命を有する高温燃焼触媒
を提供することにある。
［発明の概要］
本発明者らは、上記した現況に鑑みて、800℃
以上の高温において使用可能な触媒について鋭意
検討を重ねた結果、γ−Al2O3層にセリウム、ラ
ンタン、ストロンチウムの１種以上を添加するこ
とおよびγ−Al2O3層と強固に接着したニツケ
ル、クロム、コバルトの金属微粒子を核としその
表面に貴金属を被着する事により大幅に耐熱性が
向上する事を見出し、本発明を完成するに到つ
た。
即ち、本発明の高温燃焼触媒は耐熱性担体と、
該担体上に設けられたLa、Ce、Srのうち１種以
上を含有するγ−Al2O3の被覆層と、該γ−
Al2O3被覆層に強固に接着したNi、Cr、Coのう
ち１種以上の金属微粒子と、該金属微粒子表面に
被着したPt、Pdの少なくとも１種とから成るこ
とを特徴とするものである。
以下において、本発明を更に詳しく説明する。
本発明において使用される耐熱性担体は、1500
℃程度の高温酸化性雰囲気中においても安定な性
質を有するものであればいかなるものでもよく、
これらの具体例としては、コージライト、ムライ
ト、α−アルミナ、ジルコニアスピネル、チタニ
ア等のセラミツク製担体等が挙げられる。担体の
形状は、通常、触媒体として使用されている形状
であれば特に制限はなく、例えば、ペレツト状、
ハニカム状等が挙げられる。
本発明において使用される金属を含有するγ−
Al2O3層は、活性担体としての機能を有するもの
である。γ−Al2O3層に添加される前記金属の配
合量は、その総量がγ−Al2O3に対して５〜30重
量％であることが好ましく、更に好ましくは10〜
20重量％である。γ−Al2O3層に添加する金属量
が５重量％未満であると耐熱性の向上が少なく、
一方、30重量％を超えると前記金属の酸化物が
Al2O3の粒界に多量に析出しγ−Al2O3層の機械
的強度が低下する事がある。
本発明において使用される金属微粒子の種類は
Al2O3との接触性が良く、また貴金属との反応性
が悪いものが選択された。
さらに金属微粒子の粒径は500Å以下であるこ
とが好ましい。500Å以上になると微粒子表面に
被着した貴金属の表面積が減少するため触媒活性
が低下するので好ましくない。
本発明において使用される貴金属触媒のPt、
Pdの少なくとも１種の担持量は特に限定されな
いが触媒金属に対し0.01〜10重量％であることが
好ましい。
上記した本発明の高温燃焼触媒は、例えば、次
のようにして製造することができる。
先ず、アルミナ固型分を30％含有するアルミナ
ゾル、γ−Al2O3から成るアルミナコーテイング
組成物に、必要に応じて珪酸塩等を添加する。こ
の組成物に、La、Ce、Srの少なくとも１種を所
定量それぞれ添加する。これらの金属は、例え
ば、その金属塩化物、金属硝化物等の金属塩の形
で添加することが好ましい。
次いで、上記組成物を、例えば、ボールミル等
を用いて固形物を粉砕する。このようにして得た
コーテイング用液体を、耐熱性担体に流しかける
等の操作により被覆せしめ、常温で充分乾燥した
後、例えば、650℃で３時間程度焼成する。
次いで、Ni、Cr、Co等の金属微粒子が分散す
るアセトン溶液に前記ハニカム状担体を浸漬して
担体上に金属微粒子を担持させた後、常温で乾燥
し、空気上で650℃、３時間の焼成を行い、前記
金属粒子とアルミナ被覆層を強固に接着させた。
なお、金属微粒子を担持する場合、分散効果をあ
げるために分散媒として磁気緩和効果のあるアセ
トン溶液中に分散後添加するのが好ましい。同時
に超音波を利用するとより一層分散効果は向上す
る。
この焼成担体を、所定量の触媒金属を溶解した
溶液に浸漬し、再び、常温で充分乾燥した後、例
えば、水素雰囲気中、550℃で３時間程度焼成す
ることにより、本発明の触媒を得ることができ
る。
尚、上記触媒金属は、例えば、塩化白金酸、塩
化パラジウム等の金属塩を水等に溶解した形で使
用することが好ましい。
本発明の高温燃焼触媒が優れた耐熱性を有する
理由は明らかではないが、次のように考えること
ができる。
即ち、La，Ce，Sr等の金属をγ−Al2O3に添
加したことにより、γ−Al2O3層の結晶粒界が微
細化するためγ−Al2O3層に生じるクラツクの伝
播を阻止するために耐熱性が向上したものと考え
られる。またγ−Al2O3層の中や表面に存在する
金属微粒子は熱処理によりAI2O3と金属微粒子が
反応し、γ−Al2O3層に強固に接着するため、実
際の触媒使用温度である800〜1500℃においても
熱移動が起らない。そのため、金属微粒子に披着
した貴金属の表面積も保持されるため耐熱性が向
上したものと考えられる。
［発明の実施例］
実施例 １
次に示す組成のアルミナコーテイング組成物を
調整した。
アルミナゾル（固形分80％） 125ｇ
塩化ランタン・７水和物（金属ランタンとして15
％） 58ｇ
塩化セリウム・６水和物（金属セリウムとして５
％） 18ｇ
珪酸カルシウム ５ｇ
上記組成物を、ボールミルを用いて、常温で２
時間混合し、固型物を粉砕した。
次いで、容積が１のコージライト製ハニカム
状担体に、前記アルミナコーテイング組成物を水
に分散した液体を数回流しかけた後、常温で約１
日乾燥した。このハニカム状担体を、650℃で３
時間焼成した。
次に100ÅのNi微粒子が分散するアセトン溶液
に前記ハニカム状担体を１時間浸漬して、担体上
にNi微粒子を担持させた。次いで、このハニカ
ム状担体を乾燥した後、空気中において650℃で
３時間焼成した。
さらに、水２に白金及びパラジウムがそれぞ
れ金属として0.9ｇ存在するように塩化白金酸及
び塩化パラジウムを溶解した水溶液を調整した。
この水溶液に、前記ハニカム状担体を１時間浸漬
して、担体に貴金属触媒を含浸させた。。次いで、
このハニカム状担体を乾燥した後、水素雰囲気中
において、550℃で３時間焼成し、本発明に係る
高温燃焼触媒(A)を得た。
実施例 ２
次に示す組成のアルミナコーテイング組成物を
調製した。
アルミナゾル（固形分80％） 125ｇ
塩化ランタン・７水和物（金属ランタンとして15
％） 58ｇ
塩化セリウム・６水和物（金属セリウムとして５
％） 18ｇ
Ni金属微粒子 ５ｇ
珪酸カルシウム ５ｇ
上記組成物を、ボールミルを用いて、常温で２
時間混合し、固型物を粉砕した。
次いで、溶積が１のコージライト製ハニカム
状担体に、前記アルミナコーテイング組成物を水
に分散させた状態で数回流しかけた後、常温で約
１日乾燥した。このハニカム状担体を650℃で３
時間焼成した。
一方、水２に白金及びパラジウムがそれぞれ
金属として0.9ｇ存在するように塩化白金酸及び
塩化パラジウムを溶解した水溶液を調製した。こ
の水溶液に、前記ハニカム状担体を１時間浸漬し
て、担体に貴金属触媒を含浸させた。。次いで、
このハニカム状担体を乾燥した後、水素雰囲気中
において、550℃で３時間焼成し、本発明に係る
高温燃焼触媒(B)を得た。
実施例 ３
実施例１と同様の手法によりアルミナコーテイ
ング組成物に添加する金属塩およびアルミナ被覆
層に接着させる金属微粒子を各々変えて表に示す
ような(C)〜(N)の12種類の高温燃焼触媒を調製し
た。
［比較例］
同時に比較例としてアルミナコーテイング組成
物に金属を添加していないもの、或いは金属微粒
子を添加していないものを実施例１と同様の手法
により調製した。
実施例 ４
上記実施例１、２、３で得た14種類の高温燃焼
触媒及び比較例で得た３種類の燃焼触媒について
それぞれ、流通系試験装置を用いてその燃焼特
性、すなわち燃焼効率を評価した。燃焼効率は以
下の式（）により計算した。
燃焼効率＝100×（１−出口のメタンの
発熱量＋出口のCOの発熱量／入口のメタンの発熱量）…
…（）
なお、試験条件は、ガス流量；５／ｍｈ、燃
焼ガス濃度；メタン（CH4）１％、触媒10c.c.及び
空間速度３×104hr-1である。
次いで上記燃焼触媒を、熱処理炉に入れ、1100
℃及び1400℃でそれぞれ50時間の熱処理を施した
後、前記と同様の方法で、それぞれその燃焼特
性、すなわち燃焼効率を評価した。燃焼効率は上
記の式（）により計算した。
以上の試験により得られたそれぞれの燃焼触媒
の燃焼特性、すなわち燃焼効率から、熱処理前後
における燃焼効率の比を、触媒活性保持率として
以下に示す式（）により計算した。
触媒活性保持率＝熱処理後の燃焼効率／初期の燃焼
効率×100
……（）
それらの結果を組成と共に、表に併記した。
TECHNICAL FIELD OF THE INVENTION The present invention relates to high temperature combustion catalysts, and more particularly to high temperature combustion catalysts having high activity and long life in the temperature range of about 800°C to 1500°C. [Technical background of the invention and its problems] In recent years, with the depletion of petroleum resources, etc., in order to use energy resources efficiently, it is desirable to burn fuel at as high a temperature as possible in, for example, gas turbines. It is rare. However, in the conventional method, a mixture of fuel and air is ignited and combusted using a spark plug, etc.
There are high temperature areas exceeding 2000℃. It is known that a large amount of nitrogen oxides (NOx) is generated in this high temperature section, causing problems such as environmental pollution. In order to solve these problems, a catalytic combustion method has been proposed in which a mixture of fuel and air is combusted using a catalyst. According to this combustion method, uniform combustion is possible and the combustion temperature can be increased to about 1500° C., which is the upper limit temperature at which no NOx is generated. Currently, noble metal catalysts such as platinum (Pt) threads are known as catalysts used in catalytic combustion systems. Such a noble metal combustion catalyst, for example, as shown in FIG.
On top, γ-alumina (γ-
Al 2 O 3 ) 2 was applied, and a noble metal 3 was further supported by a dipping method. However, the above-mentioned noble metal combustion catalyst
Its heat resistance temperature is usually said to be 600°C, and the problem is that the catalyst activity rapidly decreases in a temperature range higher than that, making it unusable. The reason why the catalyst activity rapidly decreases at temperatures above 600°C can be considered as follows. First, the noble metal particles on the surface of the carrier aggregate and become coarse due to heat transfer, which reduces the catalyst surface area and lowers the combustion performance. And secondly, γ
- Since Al 2 O 3 undergoes a phase transition to α-Al 2 O 3 at temperatures from around 1000°C to higher than that, cracks occur within the Al 2 O 3 phase or between Al 2 O 3 and the carrier, causing Al This is thought to be due to the 2 O 3 phase exfoliating and falling together with the catalyst metal. Therefore, in order to improve the heat resistance of noble metal combustion catalysts, the γ-Al 2 O 3 phase was improved and the γ-Al 2 O 3
Attempts have been made to strongly adsorb Pt particles on the phase to Al 2 O 3 to prevent agglomeration due to heat transfer, and to prevent the occurrence of cracks by preventing α-alpha formation of the γ-Al 2 O 3 phase. As a result, heat-resistant combustion catalysts that can be used up to around 800°C have been developed in some automotive catalysts by adding metals to the γ-Al 2 O 3 phase. [Object of the Invention] An object of the present invention is to provide a high-temperature combustion catalyst that has high activity and long life even in the temperature range of about 800 to 1500°C. [Summary of the Invention] In view of the above-mentioned current situation, the present inventors have devised
As a result of extensive research into catalysts that can be used at these high temperatures, we found that we added one or more of cerium, lanthanum, and strontium to the γ-Al 2 O 3 layer, and that it was strongly bonded to the γ-Al 2 O 3 layer. The inventors have discovered that heat resistance can be significantly improved by using fine metal particles of nickel, chromium, or cobalt as cores and coating the surfaces with noble metals, and have completed the present invention. That is, the high-temperature combustion catalyst of the present invention comprises a heat-resistant carrier,
A coating layer of γ-Al 2 O 3 containing one or more of La, Ce, and Sr provided on the carrier;
It is characterized by comprising fine metal particles of one or more of Ni, Cr, and Co firmly adhered to the Al 2 O 3 coating layer, and at least one of Pt and Pd adhered to the surface of the fine metal particles. It is. In the following, the invention will be explained in more detail. The heat-resistant carrier used in the present invention is 1500
Any material may be used as long as it has stable properties even in a high-temperature oxidizing atmosphere of about °C.
Specific examples of these include ceramic carriers such as cordierite, mullite, α-alumina, zirconia spinel, and titania. The shape of the carrier is not particularly limited as long as it is a shape normally used as a catalyst, for example, pellet-like,
Examples include honeycomb shapes. γ- containing metal used in the present invention
The Al 2 O 3 layer functions as an active carrier. The total amount of the metal added to the γ-Al 2 O 3 layer is preferably 5 to 30% by weight, more preferably 10 to 30% by weight based on the γ-Al 2 O 3 .
It is 20% by weight. If the amount of metal added to the γ-Al 2 O 3 layer is less than 5% by weight, there will be little improvement in heat resistance;
On the other hand, if it exceeds 30% by weight, the oxides of the metals
A large amount of γ-Al 2 O 3 may precipitate at the grain boundaries, reducing the mechanical strength of the γ-Al 2 O 3 layer. The types of metal fine particles used in the present invention are
A material with good contact with Al 2 O 3 and poor reactivity with noble metals was selected. Further, the particle size of the metal fine particles is preferably 500 Å or less. When the thickness exceeds 500 Å, the surface area of the noble metal deposited on the surface of the fine particles decreases, resulting in a decrease in catalytic activity, which is not preferable. Pt, the noble metal catalyst used in the present invention,
The amount of at least one Pd supported is not particularly limited, but is preferably 0.01 to 10% by weight based on the catalyst metal. The high-temperature combustion catalyst of the present invention described above can be manufactured, for example, as follows. First, a silicate or the like is added, if necessary, to an alumina coating composition consisting of an alumina sol and γ-Al 2 O 3 containing 30% alumina solid content. A predetermined amount of at least one of La, Ce, and Sr is added to this composition. These metals are preferably added in the form of metal salts such as metal chlorides and metal nitrides. Next, the above composition is pulverized into solid matter using, for example, a ball mill. The coating liquid thus obtained is coated by pouring it onto a heat-resistant carrier, and after sufficiently drying at room temperature, it is baked at, for example, 650° C. for about 3 hours. Next, the honeycomb-shaped carrier was immersed in an acetone solution in which fine particles of metals such as Ni, Cr, Co, etc. Firing was performed to firmly adhere the metal particles and the alumina coating layer.
In addition, when supporting metal fine particles, in order to improve the dispersion effect, it is preferable to add the metal particles after dispersion in an acetone solution which has a magnetic relaxation effect as a dispersion medium. If ultrasonic waves are used at the same time, the dispersion effect will be further improved. The catalyst of the present invention is obtained by immersing this calcined support in a solution in which a predetermined amount of catalyst metal is dissolved, drying it sufficiently at room temperature again, and then calcining it at 550°C for about 3 hours in a hydrogen atmosphere, for example. be able to. The catalyst metal is preferably used in the form of a metal salt such as chloroplatinic acid or palladium chloride dissolved in water or the like. Although the reason why the high temperature combustion catalyst of the present invention has excellent heat resistance is not clear, it can be considered as follows. In other words, by adding metals such as La, Ce, and Sr to γ-Al 2 O 3 , the grain boundaries of the γ-Al 2 O 3 layer become finer, which reduces cracks that occur in the γ-Al 2 O 3 layer. It is thought that the heat resistance was improved to prevent the spread. In addition, the metal fine particles present in or on the surface of the γ-Al 2 O 3 layer react with AI 2 O 3 during heat treatment and firmly adhere to the γ-Al 2 O 3 layer. No heat transfer occurs even at temperatures between 800 and 1500°C. Therefore, it is thought that the surface area of the noble metal adhered to the metal fine particles is maintained, and thus the heat resistance is improved. [Examples of the Invention] Example 1 An alumina coating composition having the composition shown below was prepared. Alumina sol (solid content 80%) 125g Lanthanum chloride heptahydrate (15% as metal lanthanum)
%) 58g Cerium chloride hexahydrate (58g as metallic cerium)
%) 18g Calcium silicate 5g The above composition was milled at room temperature for 2 hours using a ball mill.
Mixed for an hour and ground the solids. Next, a liquid prepared by dispersing the alumina coating composition in water was poured several times onto a cordierite honeycomb-shaped carrier having a volume of 1, and then the alumina coating composition was dispersed in water at room temperature.
Dry in the sun. This honeycomb-shaped carrier was heated at 650℃ for 3
Baked for an hour. Next, the honeycomb-shaped carrier was immersed for 1 hour in an acetone solution in which Ni particles of 100 Å were dispersed, so that the Ni particles were supported on the carrier. Next, this honeycomb-shaped carrier was dried and then calcined in air at 650°C for 3 hours. Furthermore, an aqueous solution in which chloroplatinic acid and palladium chloride were dissolved was prepared so that 0.9 g of platinum and palladium each existed as metals in water 2.
The honeycomb-shaped carrier was immersed in this aqueous solution for 1 hour to impregnate the carrier with the noble metal catalyst. . Then,
After drying this honeycomb-shaped carrier, it was calcined at 550° C. for 3 hours in a hydrogen atmosphere to obtain a high-temperature combustion catalyst (A) according to the present invention. Example 2 An alumina coating composition having the composition shown below was prepared. Alumina sol (solid content 80%) 125g Lanthanum chloride heptahydrate (15% as metal lanthanum)
%) 58g Cerium chloride hexahydrate (58g as metallic cerium)
%) 18g Ni metal fine particles 5g Calcium silicate 5g The above composition was milled at room temperature for 2 hours using a ball mill.
Mixed for an hour and ground the solids. Next, the alumina coating composition dispersed in water was poured several times onto a cordierite honeycomb carrier having a volume of 1, and then dried at room temperature for about 1 day. This honeycomb-shaped carrier was heated at 650℃ for 3
Baked for an hour. On the other hand, an aqueous solution was prepared in which chloroplatinic acid and palladium chloride were dissolved in water 2 so that 0.9 g of platinum and palladium were each present as metals. The honeycomb-shaped carrier was immersed in this aqueous solution for 1 hour to impregnate the carrier with the noble metal catalyst. . Then,
After drying this honeycomb-shaped carrier, it was calcined at 550° C. for 3 hours in a hydrogen atmosphere to obtain a high-temperature combustion catalyst (B) according to the present invention. Example 3 Using the same method as in Example 1, the metal salt added to the alumina coating composition and the metal fine particles adhered to the alumina coating layer were changed, and 12 types of high temperatures (C) to (N) as shown in the table were prepared. A combustion catalyst was prepared. [Comparative Example] At the same time, as a comparative example, an alumina coating composition to which no metal was added or to which no metal fine particles were added was prepared in the same manner as in Example 1. Example 4 The combustion characteristics, that is, the combustion efficiency, of the 14 types of high-temperature combustion catalysts obtained in Examples 1, 2, and 3 above and the 3 types of combustion catalysts obtained in the comparative example were evaluated using a flow system test device. did. Combustion efficiency was calculated using the following formula (). Combustion efficiency = 100 x (1 - calorific value of methane at the outlet + calorific value of CO at the outlet / calorific value of methane at the inlet)...
...() Note that the test conditions were: gas flow rate: 5/mh, combustion gas concentration: methane (CH 4 ) 1%, catalyst 10 c.c., and space velocity 3×10 4 hr −1 . Next, the above combustion catalyst was placed in a heat treatment furnace and heated at 1100 °C.
After heat treatment at 1400°C and 1400°C for 50 hours, the combustion characteristics, ie, combustion efficiency, were evaluated in the same manner as described above. Combustion efficiency was calculated using the above formula (). From the combustion characteristics, that is, combustion efficiency, of each combustion catalyst obtained through the above tests, the ratio of combustion efficiency before and after heat treatment was calculated as the catalyst activity retention rate using the formula () shown below. Catalyst activity retention rate = combustion efficiency after heat treatment/initial combustion efficiency x 100 () The results are also listed in the table together with the composition.
【表】
表から明らかなように、本発明の高温燃焼触媒
は、比較例のものに比べて、触媒の耐熱性の指標
となる触媒活性保持率が、格段に優れていること
が確認された。
尚、上記実施例においてはハニカム状担体を使
用したが、ペレツト状担体を使用した場合にも同
様の結果が得られた。
［発明の効果］
本発明の高温漕焼触媒は、従来の貴金属系燃焼
触媒に比べて、大幅にその耐熱性が向上されたも
のである。従つて、エネルギーの節約及び効率的
利用が可能であり、又、NOx等を発生させるこ
となく燃焼が可能であるため、環境汚染等をひき
起こすことがないものである。
さらに同一の貴金属表面積を得るために必要な
貴金属量が大幅に減少し触媒の価格が大幅に低下
した事も特記しておく。[Table] As is clear from the table, it was confirmed that the high-temperature combustion catalyst of the present invention has significantly better catalytic activity retention, which is an index of the heat resistance of the catalyst, than that of the comparative example. . Although a honeycomb carrier was used in the above examples, similar results were obtained when a pellet carrier was used. [Effects of the Invention] The high-temperature column-fired catalyst of the present invention has significantly improved heat resistance compared to conventional noble metal combustion catalysts. Therefore, it is possible to save and use energy efficiently, and since combustion is possible without generating NO x etc., it does not cause environmental pollution. It should also be noted that the amount of precious metal required to obtain the same precious metal surface area has been significantly reduced, resulting in a significant reduction in the price of the catalyst.
第１図は従来の貴金属系燃焼触媒の断面図、第
２図は本発明による高温燃焼触媒の断面図であ
る。
１……担体、２……γ−Al2O3、３……貴金
属、４……金属微粒子。
FIG. 1 is a sectional view of a conventional noble metal combustion catalyst, and FIG. 2 is a sectional view of a high temperature combustion catalyst according to the present invention. DESCRIPTION OF SYMBOLS 1... Support, 2... γ- Al2O3 , 3 ... Noble metal, 4... Metal fine particles.
Claims (1)
ン（La）、セリウム（Ce）、ストロンチウム（Sr）
のうち１種以上を含有するγ−アルミナ（γ−
Al2O3）の被覆層と、該γ−アルミナ被覆層に接
着したニツケル（Ni）、クロム（Cr）、コバルト
（Co）のうち１種以上の金属微粒子と、該金属微
粒子表面に被着した白金（Pt）、パラジウム
（Pd）の少なくとも１種とから成ることを特徴と
する高温燃焼触媒。1 Heat-resistant carrier and lanthanum (La), cerium (Ce), and strontium (Sr) provided on the carrier
γ-alumina (γ-
Al 2 O 3 ) coating layer, metal fine particles of one or more of nickel (Ni), chromium (Cr), and cobalt (Co) adhered to the γ-alumina coating layer, and metal fine particles adhered to the surface of the metal fine particles. A high-temperature combustion catalyst comprising at least one of platinum (Pt) and palladium (Pd).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58042337A JPS59169536A (en) | 1983-03-16 | 1983-03-16 | High temperature combustion catalyst |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58042337A JPS59169536A (en) | 1983-03-16 | 1983-03-16 | High temperature combustion catalyst |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS59169536A JPS59169536A (en) | 1984-09-25 |
| JPH0424099B2 true JPH0424099B2 (en) | 1992-04-24 |
Family
ID=12633193
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP58042337A Granted JPS59169536A (en) | 1983-03-16 | 1983-03-16 | High temperature combustion catalyst |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS59169536A (en) |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6022929A (en) * | 1983-07-15 | 1985-02-05 | Hitachi Ltd | Heat resistant carrier for catalyst |
| JPS6133233A (en) * | 1984-07-25 | 1986-02-17 | Nippon Shokubai Kagaku Kogyo Co Ltd | Combustion catalyst for methane fuel and combustion system using said catalyst |
| JPS6135851A (en) * | 1984-07-30 | 1986-02-20 | Hitachi Ltd | Catalyst carrier stable at high temperature and its preparation |
| US6164768A (en) * | 1999-11-09 | 2000-12-26 | Illinois Tool Works Inc. | Adapter and mating bottle cap for coupling bottles to ink supplies |
| KR100387049B1 (en) * | 2000-11-23 | 2003-06-12 | 주식회사 베스트코리아 | Catalyst manufacturing method for Brown gas |
| KR100502836B1 (en) * | 2002-08-08 | 2005-07-25 | 주식회사 한국촉매 | Bimetalic catalysts manufacturing method by using centrifugal machine |
-
1983
- 1983-03-16 JP JP58042337A patent/JPS59169536A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS59169536A (en) | 1984-09-25 |
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