JP4293775B2 - Catalyzed ceramic composite, production method thereof, and ceramic membrane reactor - Google Patents
Catalyzed ceramic composite, production method thereof, and ceramic membrane reactor Download PDFInfo
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- 239000000919 ceramic Substances 0.000 title claims description 70
- 239000002131 composite material Substances 0.000 title claims description 49
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- 239000010410 layer Substances 0.000 claims description 184
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- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 4
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- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 2
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- OTMSDBZUPAUEDD-UHFFFAOYSA-N Ethane Chemical compound CC OTMSDBZUPAUEDD-UHFFFAOYSA-N 0.000 description 1
- BQCADISMDOOEFD-UHFFFAOYSA-N Silver Chemical group [Ag] BQCADISMDOOEFD-UHFFFAOYSA-N 0.000 description 1
- 229910003431 SrFe0.9Nb0.1O3−δ Inorganic materials 0.000 description 1
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- 150000004703 alkoxides Chemical class 0.000 description 1
- 150000004649 carbonic acid derivatives Chemical class 0.000 description 1
- CETPSERCERDGAM-UHFFFAOYSA-N ceric oxide Chemical compound O=[Ce]=O CETPSERCERDGAM-UHFFFAOYSA-N 0.000 description 1
- 229910000422 cerium(IV) oxide Inorganic materials 0.000 description 1
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- 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
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Images
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts
Landscapes
- Inorganic Compounds Of Heavy Metals (AREA)
- Hydrogen, Water And Hydrids (AREA)
- Catalysts (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
- Laminated Bodies (AREA)
- Compounds Of Iron (AREA)
- Compositions Of Oxide Ceramics (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、酸素含有混合ガス中の酸素成分の分離と炭化水素（メタン、天然ガス、エタン、ガソリン、灯油等）ガス或いは炭化水素含有混合ガス中の炭化水素ガス分子の酸化や部分酸化反応を単一装置内で行うことのできるセラミックス膜式反応器に使用される触媒化されたセラミックス複合材およびその製造方法、ならびに前記触媒化されたセラミックス複合材を備えてなる膜式反応器に関する。
【０００２】
【従来の技術】
酸素含有ガスからの酸素の分離は、従来から工業的に重要なプロセスであるが、現行の深冷蒸留方式に代表される酸素製造技術は、資本集約型且つエネルギー多消費型であり、プロセス形態等技術改良の進展はあるものの、本質的に沸点の極めて小さい酸素と窒素との沸点差に基づく分離技術である為、大幅なコスト削減は困難である。
【０００３】
該状況下、酸素製造技術の新機軸として、近年、特に欧米にて研究開発が急速に活発化している緻密混合導電性セラミックス膜を利用した高温（〜９００℃）酸素分離技術が、コンパクトな設備で且つ省エネルギーに繋がる可能性を有する為、大きく注目を集めている。
【０００４】
緻密混合導電性セラミックス膜では、酸素イオン及び電子は、その他の種（窒素、水、二酸化炭素等）が不透質である緻密セラミックス膜材料を通して選択的に輸送される。酸素分子は、緻密セラミックス膜表面（カソード側）で、膜の反対（アノード側）から移動してきた電子と結合して酸素イオンを生成する。酸素イオンは、緻密膜内を酸素イオンの化学ポテンシャルの差に従い拡散移動し、アノード側で電子を放出し、再び酸素分子となる。この時、電子は、酸素イオンと逆方向に移動することにより電気的中性を保つ。
【０００５】
炭化水素を含むガスを原料として、水素や合成ガス（一酸化炭素と水素の混合ガス）に改質する技術は、石油・化学プロセスにおいて重要な位置を占めており、メタン等の炭化水素を含有するガスを原料として合成液体燃料を製造する技術（Ｇａｓ−Ｔｏ−Ｌｉｑｕｉｄｓ：ＧＴＬ）や燃料電池の技術の進歩と相まって、前者は「未利用天然ガス資源等の有効活用」や「地球環境に優しいクリーンエネルギー源の供給」に、後者は「クリーン自動車への搭載」、「分散型電源の普及」、および「クリーンエネルギーの利用」に繋がるとして、国内外での研究活動が近年著しく活発化してきている。
【０００６】
該状況下、緻密混合導電性セラミックス膜を、空気等酸素含有ガスからの酸素分離のみならず、改質反応器として用いるための研究が最近加速されている。この膜式改質反応器は、膜の片側（カソード側）に空気を流し、その反対側（アノード側）に触媒を配置してメタン等の炭化水素ガスを流して部分酸化反応を起こさせる（酸素が消費される）ものであり、メタン側の酸素分圧が最小限となるため、結果的に酸素分圧差、即ち、酸素選択的透過の駆動力を最大限とすることができるという特徴を有する。又、メタン等の部分酸化反応を空気分離と同時に行う、即ち、シングルユニットにて酸素分離と酸化反応の両方を同時に行うことができることから、コンパクト且つ安価な反応器となる可能性を有する。
【０００７】
該反応器の工業化には、その基本構成材料である緻密混合導電性セラミックス膜および炭化水素部分酸化触媒の組合せにより、十分な酸素透過速度を得ることが大前提となる。セラミックス膜を酸素が透過する過程は、酸素分子が酸素イオンに分解する反応（カソード側反応）、酸素イオンの化学ポテンシャル差に依存する拡散移動、酸素イオンが酸素原子／酸素分子となりさらに炭化水素を酸化する反応（アノード側反応）の三つの過程に分割して評価することができる。単位面積当たりの酸素透過速度の向上には、これら三つの過程の速度をバランス良く上げる必要があり、さもなければ、前記過程のいずれかが律速し、全体として高酸素透過速度が得られなくなる。例えば、膜内における酸素イオンの拡散移動速度を上げる為に、緻密混合導電性セラミックス材料を薄膜化することは有効な方策となるが、その一方で、ある厚み以下でカソード側反応および／またはアノード側反応の速度が全体の酸素透過過程を支配する様になり、膜厚の減少による酸素透過速度増大効果が得られなくなる。したがって、高酸素透過速度を得るには、緻密部分の薄膜化のみならずカソード側およびアノード側反応速度の向上が重要な課題となる。
【０００８】
緻密混合導電性セラミックス膜および炭化水素部分酸化触媒の組合せにより、空気等酸素含有ガスおよび炭化水素ガスを原料として合成ガスを得る反応器の場合、セラミックス膜の炭化水素ガス側では、アノード反応である酸素イオンの酸素原子／分子化反応およびそれらと炭化水素との部分酸化反応が生じる。このような場合、セラミックス膜の炭化水素ガス側は、高レベルの還元雰囲気に曝されることになり、アノード反応を促進しつつ、還元雰囲気に耐える機能を有することを課題とする。
【０００９】
これらの課題に対し、ＷＯ９８／４１３９４には、メタン等炭化水素ガスの部分酸化反応により合成ガスを製造する為に用いる緻密混合導電性セラミックス膜に対して、該膜の空気等酸素含有ガス側に、表面積増大によるカソード反応促進を企図した多孔質層を、緻密セラミックス材料と類似材料を用いて形成し、さらに、その反対側表面には、部分酸化触媒を隣接させた３層構造の触媒化されたセラミックス複合材に関する技術が開示されているが、部分酸化触媒をなす層の構造及び材料組成に関する具体的な記載はない。
【００１０】
本発明者は、試みに、部分酸化触媒層として、酸化物担体に金属触媒を担持させた触媒層（本明細書の請求項５に記載されている多孔質反応触媒層に同じ）、緻密膜及び多孔質層として、混合導電性酸化物（本明細書の請求項４に記載されている組成の混合導電性酸化物）を用い、触媒層側にメタンガスを、多孔質層側に空気を流して、ＷＯ９８／４１３９４に記載された３層構造材料の酸素透過速度（部分酸化反応速度より算出）を測定したが、酸素透過速度は大きくなく、材料構造において、高酸素透過速度を得るための更なる改善余地があることを見出した。
【００１１】
特開平７−２４０１１５号公報には、稠密（緻密）な多成分金属酸化物層からなる膜の第１表面に、カソード反応を促進する単層の酸素解離触媒をコートし、第２表面には、アノード反応促進および稠密な膜に対する機械的強度付与を目的として、混合導電性多成分金属酸化物または工程の作動条件では混合導電性を示さない物質からなる単層または複層の多孔質層を隣接させた３層または４層構造のイオン輸送膜が開示されている。特開平７−２４０１１５号公報には、空気等の酸素含有ガスから酸素を分離する技術を主眼になされた発明であるが、同明細書の段落００１５及び請求項４６に、「炭化水素を含む有機化合物の酸化」が、前記イオン輸送膜の用途として記載されている。
【００１２】
前記イオン輸送膜においては、多孔質層またはＭＣ多孔質層（混合導電性多成分金属酸化物の多孔質層）に金属触媒及び担体を有してなる反応触媒は全く含まれていない。より具体的に言えば、前記多孔質層をなすものとして請求項に列記されている材料は、多成分金属酸化物、高温で酸素と適合する金属合金、金属酸化物安定化ジルコニア、セリア、電子または酸素を伝導しないアルミナ、マグネシア等の物質であって、金属触媒及び担体を有してなる反応触媒は含まれない。また、ＭＣ多孔質層をなす材料は多成分系金属酸化物であって、金属触媒及び担体を有してなる反応触媒はやはり含まれない。特開平７−２４０１１５号公報の発明は、基本的に、カソード側および／またはアノード側反応を促進させるイオン輸送膜の構造を規定した発明と考えられるべきものであって、イオン輸送膜を構成する材料について非常に広い範囲が請求されているが、その理由に関する説明が不十分であるために、本技術に詳しい同業者をもってしても、同明細書や簡単な試験に基づき具体的に材料を選定することは、実施例に記載されたケースを除いて事実上不可能である。
【００１３】
本発明者は、試みに、緻密膜及び膜の第２表面に隣接する多孔質層として、混合伝導性多成分金属酸化物（本明細書の請求項４に記載されている組成の混合導電性酸化物に同じ）を用い、膜の第１表面に隣接する触媒層として、酸化物担体担持金属触媒層（本明細書の請求項５に記載されている多孔質反応触媒層に同じ）を用い、段落００１５に記載されている如く、イオン輸送膜が「酸素含有供給ガスが膜の触媒化表面と接触する」ように、第２表面側にメタンガスを流し、第１表面側に空気を流して、酸素透過速度（酸化反応速度より算出）を測定した。その結果、酸素透過速度は大きくなく、材料構造に大幅な改善余地があることを見出した。尚、ガス流を入れ替えて、第１表面側にメタンガス、第２表面側に空気を流した場合は、前述したＷＯ９８／４１３９４に関して本発明者が行った測定と同一であって、この場合にも材料構造に改善余地があることは、既に説明した通りである。
【００１４】
以上述べた如く、触媒化されたセラミックス複合材を用いて、炭化水素ガス及び酸素含有ガスから合成ガス等を製造する膜式合成ガス製造技術に関して、カソード側および／またはアノード側反応を促進させる一般的な膜構造については開示されているが、それらには、両反応を促進しつつ、炭化水素部分酸化反応を安定的に生じせしめ、実機化へ向け十分に高い酸素透過速度を安定的に得る為の触媒化されたセラミックス複合材に関する具体的な技術は開示されておらず、改善余地が残されている。
【００１５】
【特許文献１】
国際公開 ＷＯ９８／４１３９４号パンフレット
【特許文献２】
特開平７−２４０１１５号公報
【００１６】
【発明が解決しようとする課題】
本発明は、酸素含有ガスおよび炭化水素ガスを原料として、合成ガスを製造する膜式反応器に用いられ、カソードおよびアノード反応を促進しつつ、炭化水素部分酸化反応を安定的に生じせしめ、従来技術よりも高い酸素透過速度を得ることができる触媒化されたセラミックス複合材の構造および構成材料の具体的組成を提供することをその課題とする。
【００１７】
【課題を解決するための手段】
本発明は、前記課題を解決すべく、多孔質触媒層、緻密質連続層、多孔質中間触媒層、および多孔質反応触媒層を複合化し、多層構造とすることによりなされたもので、その要旨とするところは、以下のとおりである。
【００１８】
（１） セラミックス膜の一面側に供給される酸素含有ガスと、前記セラミックス膜の他面側に供給される炭化水素含有ガスとから合成ガスを製造するためのセラミックス膜式反応器のセラミックス膜として用いられるセラミックス複合材において、混合導電性酸化物を有してなる選択的酸素透過性緻密質連続層の第一表面に、混合導電性酸化物を有してなり、前記酸素含有ガスが供給される側に配置される多孔質触媒層が隣接し、前記緻密質連続層の第二表面に、混合導電性酸化物、および／または燃焼触媒機能を有する触媒酸化物を有してなり、前記炭化水素含有ガスが供給される側に配置される多孔質中間触媒層が隣接し、さらに、該多孔質中間触媒層に、金属触媒及び担体を有してなる多孔質反応触媒層が隣接する多層構造体を有し、前記多孔質反応触媒層の担体の主成分がＭｇＯで、かつ、前記多孔質反応触媒層の金属触媒がＮｉ、Ｃｏ、Ｒｕ、Ｒｈ、Ｐｔ、Ｐｄ、Ｉｒ、Ｒｅから選ばれる１種または２種以上を活性金属種とする担持金属触媒であり、前記緻密質連続層、多孔質触媒層、および多孔質中間触媒層のいずれか１つ以上が組成式（１）で表される混合導電性酸化物を有してなることを特徴とする触媒化されたセラミックス複合材。
［Ｌｎ １−ａ−ｂ Ａ ａ Ｂａ ｂ ］［Ｂ ｘ Ｂ’ ｙ Ｂ” ｚ ］Ｏ ３−δ 組成式（１）（ここで、Ｌｎは、ランタノイド元素から選ばれる１種または２種以上の元素の組み合わせ、
Ａは、Ｓｒ、Ｃａ、またはこれらの元素の組み合わせ、
Ｂは、Ｃｏ、Ｆｅ、Ｃｒ、及びＧａから選ばれる１種または２種以上の元素の組み合わせで、ＣｒとＧａのモル数の和が全Ｂ元素のモル数に対し０％以上２０％以下、
Ｂ’は、Ｎｂ、Ｔａ、Ｔｉ、Ｚｒ、Ｉｎ、及びＹから選ばれる１種または２種以上の元素の組み合わせで、Ｎｂ、Ｔａ、Ｉｎ、Ｙの少なくとも１種を含む、
Ｂ”は、Ｚｎ、Ｌｉ、Ｍｇから選ばれる１種または２種以上の元素の組み合わせ、
０．８≦ａ＋ｂ≦１、
ｂは、Ｂ’がＩｎのみで構成される場合には０．４≦ｂ≦１．０、Ｂ’がＹのみで構成される場合には０．５≦ｂ≦１．０、Ｂ’がＩｎおよびＹのみで構成される場合には０．２≦ｂ≦１．０、Ｂ’がＩｎ、Ｙ以外の元素を含む場合には０≦ｂ≦１．０、
０＜ｘ、
０＜ｙ≦０．５、
０≦ｚ≦０．２、
０．９８≦ｘ＋ｙ＋ｚ≦１．０２、
δは、電荷中性条件を満たすように決まる値である。）
【００１９】
（２） 前記多層構造体が、多孔質支持体上に被覆層として形成されていることを特徴とする前記（１）に記載の触媒化されたセラミックス複合材。
【００２１】
（３）前記燃焼触媒機能を有する触媒酸化物が、Ｃｏ、Ｆｅ、Ｍｎ、Ｐｄから選ばれる１種または２種以上を含むことを特徴とする前記（１）又は（２）に記載の触媒化されたセラミックス複合材。
【００２３】
（４） 前記金属触媒の単位膜面積当たりの質量が、２０〜５０ｍｇ／ｃｍ２であることを特徴とする前記（１）〜（３）の何れかに記載の触媒化されたセラミックス複合材。
【００２４】
（５） セラミックス膜の一面側に供給される酸素含有ガスと、前記セラミックス膜の他面側に供給される炭化水素含有ガスとから合成ガスを製造するためのセラミックス膜式反応器のセラミックス膜として用いられるセラミックス複合材の製造方法において、組成式（１）で表される混合導電性酸化物を有してなる緻密質連続層の第一表面および第二表面に、粒径１０μｍ以下で組成式（１）で表される混合導電性酸化物の微粉体を有機溶剤と混合してスラリー化したものを塗布・乾燥し、９５０℃以上１５００℃以下で焼き付けを行い、それぞれ前記酸素供給ガスが供給される側に配置される多孔質触媒層および前記炭化水素含有ガスが供給される側に配置される多孔質中間触媒層とし、さらに、該多孔質中間触媒層上に、ＭｇＯを主成分とする担体にＮｉ、Ｃｏ、Ｒｕ、Ｒｈ、Ｐｔ、Ｐｄ、Ｉｒ、Ｒｅから選ばれる１種または２種以上の活性金属種を担持した金属担持触媒の微粉末に、前記多孔質中間触媒層の材料微粉末を加え、有機溶剤を混合してスラリー化したものを塗布・乾燥し、９５０℃以上１５００℃以下で焼き付けを行うことを特徴とする触媒化されたセラミックス複合材の製造方法。
［Ｌｎ１−ａ−ｂＡａＢａｂ］［ＢｘＢ’ｙＢ”ｚ］Ｏ３−δ 組成式（１）ここで、Ｌｎは、ランタノイド元素から選ばれる１種または２種以上の元素の組み合わせ、
Ａは、Ｓｒ、Ｃａ、またはこれらの元素の組み合わせ、
Ｂは、Ｃｏ、Ｆｅ、Ｃｒ、及びＧａから選ばれる１種または２種以上の元素の組み合わせで、ＣｒとＧａのモル数の和が全Ｂ元素のモル数に対し０％以上２０％以下、
Ｂ’は、Ｎｂ、Ｔａ、Ｔｉ、Ｚｒ、Ｉｎ、及びＹから選ばれる１種または２種以上の元素の組み合わせで、Ｎｂ、Ｔａ、Ｉｎ、Ｙの少なくとも１種を含む、
Ｂ”は、Ｚｎ、Ｌｉ、Ｍｇから選ばれる１種または２種以上の元素の組み合わせ、
０．８≦ａ＋ｂ≦１、
ｂは、Ｂ’がＩｎのみで構成される場合には０．４≦ｂ≦１．０、Ｂ’がＹのみで構成される場合には０．５≦ｂ≦１．０、Ｂ’がＩｎおよびＹのみで構成される場合には０．２≦ｂ≦１．０、Ｂ’がＩｎ、Ｙ以外の元素を含む場合には０≦ｂ≦１．０、
０＜ｘ、
０＜ｙ≦０．５、
０≦ｚ≦０．２、
０．９８≦ｘ＋ｙ＋ｚ≦１．０２、
δは、電荷中性条件を満たすように決まる値である。
【００２５】
（６） 前記（１）〜（４）のいずれかに記載の触媒化されたセラミックス複合材を備えてなることを特徴とするセラミックス膜式反応器。
【００２６】
【発明の実施の形態】
以下、本発明の触媒化されたセラミックス複合材について説明する。
【００２７】
前述したように、単位面積当たりの酸素透過速度（合成ガス製造速度）の向上には、カソード側反応、酸素イオンの拡散移動、アノード側反応の三つの過程をバランス良く向上する必要がある。
【００２８】
本発明者はまず、酸素含有ガス中の酸素分子を酸素イオンにするカソード側反応促進方法として、一般的に知られている、反応場の増大、即ち、多孔質触媒層付加により得られる表面積の増大に着目した。混合導電性酸化物を有して成る多孔質触媒層を緻密質連続層の第１表面に隣接させることにより、カソード反応の顕著な促進が達成される。本発明の多孔質触媒層の材料としては、高酸素透過性を有する混合導電性のペロブスカイト型酸化物が適する。本発明者は、多孔質触媒層の材料について、高酸素透過性を有するものを鋭意探索した結果、組成が、下式（１）
［Ｌｎ1-a-bＡaＢａb］［ＢxＢ’yＢ”z］Ｏ3- δ （１）
（ただし、Ｌｎは、ランタノイド元素から選ばれる１種または２種以上の元素の組み合わせである。Ａは、Ｓｒ、Ｃａ、またはこれらの元素の組み合わせである。Ｂは、Ｃｏ、Ｆｅ、Ｃｒ、及びＧａの中から選ばれる１種または２種以上の元素の組み合わせで、ＣｒとＧａのモル数の和が、全Ｂ元素のモル数に対し、０％以上２０％以下である。Ｂ’は、Ｎｂ、Ｔａ、Ｔｉ、Ｚｒ、Ｉｎ、及びＹから選ばれる１種または２種以上の元素の組み合わせで、Ｎｂ、Ｔａ、Ｉｎ、Ｙの少なくとも１種を含む。Ｂ”は、Ｚｎ、Ｌｉ、Ｍｇから選ばれる１種または２種以上の元素の組み合わせである。０．８≦ａ＋ｂ≦１である。ｂは、Ｂ’がＩｎのみで構成される場合には０．４≦ｂ≦１．０、Ｂ’がＹのみで構成される場合には０．５≦ｂ≦１．０、Ｂ’がＩｎおよびＹのみで構成される場合には０．２≦ｂ≦１．０である。０．９８≦ｘ＋ｙ＋ｚ≦１．０２で、０＜ｘ、０＜ｙ≦０．５、０≦ｚ≦０．２である。δは、電荷中性条件を満たすように決まる値である。）
で表されるペロブスカイト型酸化物よりなる材料を見出した。
【００２９】
緻密質連続層における酸素イオン拡散速度の増大には、一般的に知られているように、高イオン導電性のペロブスカイト型酸化物を材料として用いることが適当である。本発明者は、具体的材料として、高イオン導電性であって、かつ多孔質触媒層材料および多孔質中間触媒層材料との適合性（多孔層焼き付け時に剥離が生じないこと等）を有するものを鋭意探索した結果、前記多孔質触媒層と同様の材料、すなわち、前式（１）で表されるペロブスカイト型酸化物よりなる材料が適当であることを見出した。
【００３０】
一方、メタン等炭化水素ガスが酸化されるアノード側反応の促進方法に関し、本発明者は、従来知られている多孔質反応触媒層を緻密質連続層に隣接させるのではなく、混合導電性酸化物および／または燃焼触媒機能を有する触媒酸化物からなる多孔質中間触媒層を緻密質連続層に隣接させ、この多孔質中間触媒層を介して多孔質反応触媒層を隣接させる構造が、アノード側反応促進に極めて有効であることを新たに見出した。
【００３１】
本発明の多孔質中間触媒層の材料には、炭化水素等による還元雰囲気に於いても安定的にアノード側反応を促進することができるよう、耐還元性が高く、高酸素透過性の混合導電性酸化物が適する。本発明者は、多孔質中間触媒層に用いるべく、混合導電性、高酸素透過性で、かつ耐還元性を有するペロブスカイト型酸化物について鋭意探索した結果、前記多孔質触媒層、あるいは緻密質連続層と同様の組成材料、すなわち、前式（１）で表されるペロブスカイト型酸化物が、これらの条件を満足することを見出した。さらに、本発明の多孔質中間触媒層には、混合導電性は有しないが燃焼触媒機能を有する触媒酸化物、即ち、Ｃｏ、Ｆｅ、Ｍｎ、Ｐｄの内の１種または２種以上を含む酸化物も有効である。本発明の多孔質中間触媒層には、これらの混合伝導性酸化物と触媒酸化物の両方を同時に用いても良いし、片方のみを用いても良い。
【００３２】
また、多孔質反応触媒層をなす材料について、本発明者は、高温操業を考慮して、多孔質中間触媒層を構成するペロブスカイト型酸化物と反応せず、かつ多孔質中間触媒層材料との適合性（焼き付け時に剥離が生じないこと等）を有するものを鋭意探索した結果、多孔質反応触媒層に用いる触媒担体として、反応性が極めて低いＭｇＯが好適であり、さらに反応触媒としてＮｉ、Ｃｏ、Ｒｕ、Ｒｈ、Ｐｔ、Ｐｄ、Ｉｒ、Ｒｅから選ばれる１種または２種以上の活性金属種を担体に担持させることが好適であることを見出した。
【００３３】
尚、多孔質反応触媒層がなく、混合導電性酸化物を有してなる多孔質中間触媒層のみの場合には、アノード側反応として炭化水素の完全酸化反応が促進されるため、合成ガス製造の目的にはそぐわなくなる。したがって、この場合は本発明の範囲に含まれない。
【００３４】
本発明において、本発明者が企図したことと従来の技術との関係について述べる。
【００３５】
カソード側の多孔質触媒層及び緻密質連続層（緻密膜部）については、構造的には従来技術と大きく変わる点はないが、本発明では、この部位に適する材料を具体的に提示している。次に、アノード側の構成であるが、この部分は従来の技術に比較して大きく異なる。本発明者は、アノード側の反応を炭化水素の完全酸化反応、及び完全酸化反応生成物の改質反応に分割し、これらの反応を隣接した２つの層で逐次的に進行させる方法により、合成ガスを生成させるという新たな方策を発明した。アノード側の反応を２段階化することによって、安定的に、高酸素透過速度を得つつ、炭化水素部分酸化反応を行わせることが初めて可能になる。炭化水素の完全酸化反応は、混合導電性多孔質中間触媒層によって行われる。
【００３６】
この完全酸化反応を迅速に進行させる触媒としては、混合導電性酸化物が適している。これは、同材料が、緻密質連続層を拡散してきた酸素イオンを同材料表面で酸素原子とするアノード反応を進行させ、さらにその酸素原子が、触媒表面に吸着している炭化水素分子を直ちに酸化分解するという特性を有するためである。
【００３７】
多孔質中間触媒層の多孔質化は、反応表面積を大きくして完全酸化反応速度を増大させるとともに、炭化水素等の原料ガス、及び反応生成物としての水蒸気及び二酸化炭素の交換が、迅速に行われるために必須である。
【００３８】
水蒸気及び二酸化炭素ガスによる炭化水素等の改質反応（合成ガス生成反応）には、改質反応触媒として知られているＮｉ、Ｃｏ、Ｒｕ、Ｒｈ、Ｐｔ、Ｐｄ、Ｉｒ、Ｒｅから選ばれる１種または２種以上の活性金属種を利用すれば良いが、反応表面積を大きくして反応速度を増大させるとともに、炭化水素等の原料ガス、水蒸気、二酸化炭素、合成ガス等、種々のガス種の交換が迅速に行われるよう、担体に担持させて、多孔質反応触媒層とすることが必要である。本発明者は、アノード側反応に対して、上記の新しい構造を発明しただけでなく、この部位に適する材料を具体的に提示している。
【００３９】
本発明の触媒化されたセラミックス複合材に好適に使用されるペロブスカイト型酸化物について、さらに詳しく説明する。
【００４０】
ペロブスカイト型酸化物は、一般式ＡＢＯ3（Ａ及びＢは金属イオン）の密に充填された格子を持つ構造体からなり、これまで、ペロブスカイト酸化物構造を有する多数の化合物が報告されている。金属イオンＡ及びＢの、物理化学的及び結晶学的因子に関する条件が満たされれば、ＡＢＯ3の形で結晶化する。
【００４１】
ここで、金属イオンの価数の合計が酸素イオンの価数の合計、即ち−（マイナス）６価を相殺する＋（プラス）６価であれば酸素空孔を生じないが、金属イオンの価数の合計が６価よりも小さい場合には、電気的平衡を保つために酸素イオンが除去され、酸素空孔が生じ、これが酸素イオン導電性を与えると考えられている。一方、電子導電性は、一般的に遷移元素と酸素との結合間で、遷移元素の価数の変化によるホッピング伝導によるものと考えられている。したがって、混合導電性を有するペロブスカイト酸化物には、Ｂサイトに遷移元素が配置され、Ａサイトには酸素空孔を生じせしめるランタノイド元素とアルカリ土類元素との組合せ、またはアルカリ土類金属単独が配置され、これらにより電子およびイオン導電性が付与される。これらＡサイト元素およびＢサイト元素の組み合わせにより、異なる混合導電性あるいは耐還元性が発現する。
【００４２】
本発明は、多孔質中間触媒層材料については、Ｂサイトに配置された場合に高酸素イオン導電性を発現しつつ比較的高い耐還元性を有するＦｅに着目し、また、緻密質連続層及び多孔質触媒層材料についてはＢサイトに配置された場合に非常に大きな酸素イオン導電性を発現するＣｏに着目し、Ａサイト元素、およびＦｅまたはＣｏを含むＢサイト元素の種々の組合せにつき、精力的に検討した結果なされたものである。
【００４３】
前式（１）のＢの構成元素において、ＣｒとＧａのモル数の和を全Ｂ元素のモル数に対し、２０％以下に限定するのは、ＣｒとＧａの含有量が２０％を超えると、酸素イオン導電性が低下するからである。Ｂ’がＩｎのみ、Ｙのみ、ＩｎおよびＹのみの場合について、ｂの範囲を限定するのは、ｂがこれらの範囲外ではペロブスカイト型構造の安定性が低下するからである。Ｂ’がＩｎ、Ｙ以外の元素を含む場合には、０≦ｂ≦１．０の範囲でペロブスカイト型構造は安定である。ａ＋ｂの範囲を限定するのは、ａ＋ｂがこの範囲を外れると、酸素イオン導電性が低下するからである。ｙの範囲を０．５以下に限定するのは、この範囲を超えてＮｂ、Ｔａ、Ｔｉ、Ｚｒ、Ｉｎ、Ｙを含有すると、酸素イオン導電性が低下するからである。ｚの範囲を０．２以下に限定するのは、この範囲を超えてＺｎ、Ｌｉ、Ｍｇを含有すると、酸素イオン導電性が低下したり、ペロブスカイト型構造の安定性が低下する問題を生じるからである。さらに、ｘ＋ｙ＋ｚの範囲を限定するのは、ｘ＋ｙ＋ｚがこの範囲を外れると、酸素イオン導電性が低下する問題を生じるからである。尚、緻密質連続層材料、多孔質触媒材料、および多孔質中間触媒層の混合伝導性酸化物は、同一組成でなくとも構わない。
【００４４】
本発明において、多孔質触媒層、緻密質連続層、多孔質中間触媒層、多孔質反応触媒層からなる多層構造は多孔質支持体上に被覆層として形成されても良い。この構造であれば、機械的強度を高くすることができるため、カソード側とアノード側の原料ガスの圧力が異なり、緻密質連続層を介して全圧の差がある場合の耐性が増す。多孔質支持体材料は、機械的強度があり、前記多層構造との適合性があるものであれば何でも良く、例えば混合導電性酸化物であっても良い。また、多孔質触媒層を厚くして、多孔質支持体としての機能をあわせ持つようにしても良い。
【００４５】
本発明に係る緻密質連続層の厚さは１μｍ以上２ｍｍ以下であり、好ましくは１０μｍ以上１．５ｍｍ以下、さらに好ましくは３０μｍ以上１ｍｍ以下である。緻密質連続層があまりに厚いと酸素透過速度を大きくできず、逆に、あまりに薄いと機械的信頼性に乏しくなることから、厚さには前述した如く適正な範囲がある。
【００４６】
本発明に係る多孔質中間触媒層および多孔質触媒層の厚さは、それぞれ１μｍ以上１ｍｍ以下および１μｍ以上５ｍｍ以下の範囲である。また、多孔質中間触媒層及び多孔質触媒層の気孔率は、２０％以上８０％以下の範囲であり、好ましくは３０％以上６０％以下の範囲である。気孔率が２０％未満では原料ガス及び反応生成物の移動が阻害されて酸素透過速度（合成ガス製造速度）が上がらず、逆に、８０％超では機械的信頼性に乏しくなる。
【００４７】
本発明に係る多孔質反応触媒層材料については、前記の如く、ＭｇＯを主成分とする担体に、水蒸気および二酸化炭素による炭化水素の改質に活性を有するＮｉ、Ｃｏ、Ｒｕ、Ｒｈ、Ｐｔ、Ｐｄ、Ｉｒ、Ｒｅの中から選ばれる１種または２種以上の活性金属種を担持したものが、活性、多孔質中間触媒層との適合性の観点から望ましい。尚、多孔質反応触媒層は、炭化水素改質のみならず、炭化水素等の完全酸化反応が起こる多孔質中間触媒層において発生する熱を、多孔質反応触媒層（吸熱反応が起こる）へ移動させることにより、材料劣化に繋がるホットスポット形成の回避という重要な役割を果たす。
【００４８】
次に、本発明材料の製造方法について説明する。
【００４９】
本発明に係る多孔質触媒層、緻密質連続層、多孔質中間触媒層、多孔質反応触媒層を構成するセラミックス材料の原料は、金属酸化物や炭酸塩を初めとする金属塩を用い、それらを混合、焼成することにより調製する。粉体原料の調製には、共沈法や金属アルコキシド法（ゾルゲル法）、或いはそれらと同等の調製法を用いても構わない。混合された原料粉体は８００℃以上１５００℃以下で仮焼する。
【００５０】
緻密質連続層を構成する材料は、仮焼後の試料を微細に粉砕し、均一に混合した後に成形する。成形はＣＩＰ（冷間静水圧プレス）、ＨＩＰ（熱間静水圧プレス）、金型プレス、射出成形法、スリップキャスト法、押し出し成型法等の任意の好適なセラミックス製造技術を適用し、成形した試料は１０５０℃以上１５００℃以下で本焼成する。
【００５１】
多孔質触媒層および多孔質中間触媒層材料は、原料の調製、混合、仮焼、粉砕を行った後、緻密質連続層の製造とは異なり、成形を行うことなく１０５０℃以上１５００℃以下で本焼成する。ここで、原料が均一に混合されていれば、中間の仮焼を省いて本焼成しても構わない。本焼成の温度範囲は、混合導電性を発現するペロブスカイト型構造となる１０５０℃以上１５００℃以下とする。本焼成した試料は、ボールミル等好適な方法にて微粉砕する。粉砕粉の粒径は、後述する理由により１０μｍ以下とすることが望ましい。
【００５２】
多孔質触媒層および多孔質中間触媒層の形成は、前記粉砕粉を有機溶剤等と混合してスラリーとし、緻密質連続層表面を覆うようにコート、乾燥した後、焼き付け（焼成）することにより行う。一般に、塗布する粉体の粒子径は、小さく揃っている程、あるいは薄く塗布する程、均一に膜表面に付着することができる。具体的には、粉体の粒径を１０μｍ以下とすることが望ましい。上記以外にも、多孔質中間触媒層の形成手段としては、ＣＶＤ（化学蒸着）法、電気泳動法、ゾル−ゲル法、或いは、これ以外の任意の好適な方法を用いることができる。
【００５３】
これらの方法により形成された多孔質層は、緻密質連続層との界面において混合導電性に関する連続性を確保するために、多孔質層および緻密質連続層が強固に接合する様、焼成される。焼成温度は、多孔質層、緻密質連続層を形成する材料の内、低い材料の融点未満で、強固な接合が得られる好適な温度を選定する。本発明において具体的に提示された材料の場合、焼き付け温度９５０℃以上１５００℃以下で強固な接合が得られるため好ましい。
【００５４】
多孔質反応触媒層を構成する触媒材料は、マグネシアを主成分とする担体に、Ｎｉ、Ｃｏ、Ｒｕ、Ｒｈ、Ｐｔ、Ｐｄ、Ｉｒ、Ｒｅの中から選ばれる１種または２種以上の活性金属種を担持したものが望ましい。触媒調製方法は、含浸担持法、平衡吸着法、共沈法等、任意のものを選択できる。活性金属種の担持量は、担体に対し、ＮｉおよびＣｏの場合は３〜３０ｍｏｌ％、Ｒｕの場合は０．１〜１０質量％、Ｒｈ、Ｐｔ、Ｐｄ、Ｉｒ、Ｒｅの場合は０．０１〜３質量％が望ましく、これらを組み合わせても良い。また、活性金属種を高分散させる為に、ＮｉまたはＣｏをマグネシアに固溶させても良く、この場合は共沈法、あるいはセラミックス法を用いる。
【００５５】
多孔質反応触媒層は、前記調製触媒の微粉砕粉に多孔質中間触媒層の材料微粉末を０．１質量％以上３０質量％以下加え、十分に混合した後、該混合粉を有機溶剤等と混合してスラリーとして、多孔質中間触媒層にコート、乾燥した後、焼き付けること（焼成）により形成される。一般に、塗布される粉体の粒子径が小さく揃っている程、あるいは薄く塗布する程、均一に膜表面に付着させることができる。具体的には粉体の粒径を０．５μｍ以上１０μｍ以下とすることが望ましい。焼成温度は、実際の膜式反応器の運転温度より少なくとも５０℃以上高く、かつ、セラミックス複合材料の融点より低い温度範囲で、強固な接合が得られる好適温度を選択し、空気中で焼き付けることが望ましい。本発明において具体的に提示された材料の場合、焼き付け温度が９５０℃以上１５００℃以下で強固な接合が得られる。また、単位膜面積当たりの触媒質量は、２０〜５０ｍｇ／ｃｍ2とするのが好適である。また、膜式反応器の運転条件によっては、反応触媒を整粒し、多孔質中間触媒層上に焼き付けることなく配置する方法もある。さらには、上記スラリーコートと整粒触媒配置との組合せとする方法もある。
【００５６】
【実施例】
以下、本発明を実施例により説明する。なお、本発明は、実施例に限定されるものではない。
【００５７】
（実施例１）
純度９９％以上のＳｒＣＯ3、Ｆｅ2Ｏ3、およびＮｂ2Ｏ5の市販パウダーを、モル比でＳｒ：Ｆｅ：Ｎｂ＝１：０．９：０．１となるように秤量し、遊星ボールミルを用いて２時間湿式混合した。得られた原料粉末をアルミナ製のるつぼに入れ、空気中１３５０℃に於いて５時間焼成し、複合酸化物を得た。この複合酸化物の室温粉末Ｘ線回折測定結果は、主成分が立方晶系ペロブスカイト型構造であることを示し、組成がＳｒＦｅ0.9Ｎｂ0.1Ｏ3- δで表される複合酸化物であることを確認した。この複合酸化物を自動乳鉢により粒径１０μｍ以下の粉末状にし、多孔質中間触媒層材料を得た。
【００５８】
次に、純度９９％以上のＢａＣＯ3、ＳｒＣＯ3、ＣｏＯ、およびＦｅ2Ｏ3の市販パウダーを、モル比でＢａ：Ｓｒ：Ｃｏ：Ｆｅ＝０．５：０．５：０．８：０．２となるように秤量し、遊星ボールミルを用いて２時間湿式混合した。得られた原料粉末をアルミナのるつぼに入れて、大気中で温度９５０℃において２０時間仮焼し、複合酸化物を得た。この複合酸化物を遊星ボールミルで２時間湿式粉砕した後、この粉末３ｇを直径２０ｍｍの金型にて、２５ＭＰａでディスク状に成形した。この成形体を気密性の袋に入れて脱気し、真空にした後、これを２００ＭＰａに加圧しながらＣＩＰを１５分間施し、空気中、温度１１３０℃で５時間本焼成し、相対密度９５％以上の緻密化した焼結体を得た。この焼結体の室温粉末Ｘ線回折測定結果は、主成分が立方晶系ペロブスカイト型構造であることを示し、組成がＢａ0.5Ｓｒ0.5Ｃｏ0.8Ｆｅ0.2Ｏ3- δで表される複合酸化物であることを確認した。この焼結体の両面を研削、研磨して、直径１２ｍｍ、厚さ０．７ｍｍのディスク形状とし、これを緻密質連続層として用いた。
【００５９】
続いて同様の手法により得られた組成がＢａ0.5Ｓｒ0.5Ｃｏ0.8Ｆｅ0.2Ｏ3- δで表される焼結体を粒径１０μｍ以下に粉砕し、多孔質触媒層材料を得た。これを有機溶剤に懸濁させスラリー状とし、前記ディスク形状の緻密質連続層の第１表面に塗布した。さらに、前記多孔質中間層材料を同様にスラリー状にし、同緻密質連続層の第２表面に塗布した。これを１２０℃で５分間乾燥後、空気中１０５０℃で５時間焼成することにより、緻密質連続層に強固に接合した多孔質触媒層および多孔質中間触媒層を得た。この時、多孔質触媒層および多孔質中間触媒層の厚さは、それぞれ、０．３および０．２ｍｍであった。
【００６０】
この多孔質中間触媒層上に、マグネシアにＮｉをＭｇに対し１０ｍｏｌ％固溶させた炭化水素改質触媒の粒径１０μｍ以下とした粉末２８ｍｇに、前記多孔質中間触媒層の材料微粉末５ｍｇを加え、十分に混合したものを有機溶剤に懸濁させスラリーコートした。これを１２０℃で５分間乾燥後、空気中１０５０℃で５時間焼成することにより、多孔質中間触媒層に炭化水素改質触媒層（多孔質反応触媒層）を接合して、本発明の触媒化されたセラミック複合材を得て、酸素透過（合成ガス製造）実験に供した。
【００６１】
実験は、前記触媒化されたセラミックス複合材を、銀リングを介して２本のムライト管で挟みこみ、カソード側とアノード側の気密性を保ちつつ、温度９００℃、圧力１０気圧にて行った。原料ガスについては、カソード側に空気を２００ｃｃ／ｍｉｎ供給し、アノード側にはメタンを４０ｃｃ／ｍｉｎ供給した。アノード側出口ガスをガスクロマトグラフで測定し、元素バランスにより、空気側からメタン側への安定した状態における酸素透過速度を計算した結果、２１ｃｃ／ｍｉｎ／ｃｍ2であった。また、この時、メタン反応転化率は５８％、ＣＯ選択率（ＣＯおよびＣＯ2中のＣＯ比率）は８０％、Ｈ2／ＣＯ比は１．８であった。
【００６２】
実験中、本発明の触媒化されたセラミックス複合材の緻密連続層にクラック等の発生はなく、経時的破壊の兆候は全く認められなかった。また、本発明の触媒化されたセラミックス複合材は、実験開始直後の期間を除き、安定した酸素透過（合成ガス生成）速度を示し、劣化の兆候は認められなかった。
【００６３】
（実施例２）
実施例１と同様の方法及び条件により作製した多孔質触媒層、緻密質連続層、多孔質中間触媒層からなるディスク状複合体を用い、マグネシアにＮｉをＭｇに対して５ｍｏｌ％含浸担持した炭化水素改質触媒の粒径１０μｍ以下とした粉末３０ｍｇに、前記多孔質中間触媒層の材料微粉末５ｍｇを加えて十分に混合したものを有機溶剤に懸濁させ、これを前記多孔質中間触媒層上にスラリーコートした。これを１２０℃で５分間乾燥後、空気中１０５０℃で５時間焼成することにより、多孔質中間触媒層に炭化水素改質触媒層（多孔質反応触媒層）を接合して、本発明の触媒化されたセラミックス複合材を得た。
【００６４】
酸素透過実験は、この複合材の多孔質反応触媒層上に、２０／４０メッシュに整粒したマグネシアに２質量％のＲｕを含浸担持させた炭化水素改質触媒を９００ｍｇ配置すること、及び、圧力が１気圧である以外は、実施例１に示したものと同様の方法及び条件で行った。安定した状態における酸素透過速度を計算した結果、２５ｃｃ／ｍｉｎ／ｃｍ2であった。また、この時、メタン反応転化率は８３％、ＣＯ選択率（ＣＯおよびＣＯ2中のＣＯ比率）は８６％、Ｈ2／ＣＯ比は１．９であった。
【００６５】
実験中、本発明の触媒化されたセラミックス複合材の緻密連続層にクラック等の発生はなく、経時的破壊の兆候は全く認められなかった。また、本発明の触媒化されたセラミックス複合材は、実験開始直後の期間を除き、安定した酸素透過（合成ガス生成）速度を示し、劣化の兆候は認められなかった。
【００６６】
（実施例３）
実施例１と同様の方法及び条件で、表１に示した本発明の触媒及びセラミックス複合材料を製造し、実施例１と同じ方法及び条件で酸素透過（合成ガス製造）特性を評価したところ、全てのものについて２０ｃｃ／ｍｉｎ／ｃｍ2以上の酸素透過速度が得られた。また、実施例１の結果と同じく、安定した酸素透過（合成ガス生成）速度を示し、劣化及び経時的破壊の兆候は全く認められなかった。
【表１】
（比較例１）
実施例１と同様の方法及び条件で、多孔質触媒層および緻密質連続層から成る触媒化されたセラミックス複合材を作製した後、該緻密質連続層上に２０／４０メッシュに整粒したマグネシアに２質量％のＲｕを含浸担持させた炭化水素改質触媒９００ｍｇを配置し、酸素透過実験に供した。
【００６８】
実験は、実施例１と同様の方法及び条件で行い、安定した状態における酸素透過速度を計算した結果、１８ｃｃ／ｍｉｎ／ｃｍ2であった。また、この時、メタン反応転化率は７６％、ＣＯ選択率（ＣＯおよびＣＯ2中のＣＯ比率）は９６％、Ｈ2／ＣＯ比は２．０であった。
【００６９】
（比較例２）
中間多孔質触媒層材料として、Ｂａ ０．５ Ｓｒ ０．５ Ｃｏ ０．８ Ｆｅ ０．２ Ｏ ３−δ で表される複合酸化物を用いる以外は、実施例１と同様の方法及び条件で、多孔質触媒層、緻密質連続層および多孔質中間触媒層から成る触媒化されたセラミックス複合材を作製した後、多孔質中間触媒層上にマグネシア担体に２質量％のＲｕを含浸担持させ、２０／４０メッシュに整粒した炭化水素改質触媒９００ｍｇを配置し、酸素透過実験に供した。
【００７０】
実験は、実施例１と同様の方法及び条件で行い、実験開始数時間後には約２３ｃｃ／ｍｉｎ／ｃｍ ２ の酸素透過速度を得たが、経時的に酸素透過速度が減少し、安定した酸素透過速度は得られなかった。
【００７１】
（比較例３）
実施例１と同様の方法及び条件で作製した多孔質触媒層、緻密質連続層、多孔質中間触媒層からなるディスク状複合体の多孔質中間触媒層上に、アルミナ（α型）担体に２質量％のＲｕを含浸担持した炭化水素改質触媒の粒径１０μｍ以下とした粉末３０ｍｇを有機溶剤に懸濁させたものをスラリーコートした。これを１２０℃で５分間乾燥後、空気中１０５０℃で５時間焼成することにより、多孔質中間触媒層に接合した炭化水素改質触媒層を得、酸素透過実験に供した。実験は、圧力が１０気圧である以外は、実施例１と同様の方法及び条件で行い、実験開始数時間後には約２０ｃｃ／ｍｉｎ／ｃｍ２の酸素透過速度を得たが、経時的に酸素透過速度が減少し、安定した酸素透過速度は得られなかった。
【００７２】
【発明の効果】
本発明によれば、酸素含有ガス中の酸素成分を選択的に輸送するのに際し、安定して高酸素透過速度を得る高性能隔膜部材が得られるため、炭化水素の部分酸化による合成ガス製造用膜式反応器等に好適に使用でき、これら装置の高性能化、低コスト化に繋がるコンパクト化に資する。
【図面の簡単な説明】
【図１】 本発明の多孔質触媒層、緻密質連続層、多孔質中間触媒層、反応触媒層からなる多層構造の触媒およびセラミックス複合材料の構造概念図である。[0001]
BACKGROUND OF THE INVENTION
The present invention separates oxygen components in an oxygen-containing mixed gas and oxidizes or partially oxidizes hydrocarbon gas molecules in a hydrocarbon (methane, natural gas, ethane, gasoline, kerosene, etc.) gas or a hydrocarbon-containing mixed gas. The present invention relates to a catalyzed ceramic composite material used in a ceramic membrane reactor that can be carried out in a single apparatus, a method for producing the same, and a membrane reactor including the catalyzed ceramic composite material.
[0002]
[Prior art]
Although the separation of oxygen from oxygen-containing gas has been an industrially important process, the oxygen production technology represented by the current cryogenic distillation method is capital intensive and energy intensive, Although there is progress in technological improvement, it is a separation technique based on the difference in boiling point between oxygen and nitrogen, which have essentially a very low boiling point, and thus it is difficult to significantly reduce costs.
[0003]
Under such circumstances, high-temperature (up to 900 ° C) oxygen separation technology using dense mixed conductive ceramic membranes, which has recently been actively researched and developed especially in Europe and the United States, is a new facility for oxygen production technology. In addition, it has attracted much attention because it has the potential to save energy.
[0004]
In a dense mixed conductive ceramic film, oxygen ions and electrons are selectively transported through a dense ceramic film material in which other species (nitrogen, water, carbon dioxide, etc.) are impervious. Oxygen molecules combine with electrons moving from the opposite side (anode side) of the dense ceramic film surface (cathode side) to generate oxygen ions. Oxygen ions diffuse and move in the dense film according to the difference in chemical potential of oxygen ions, release electrons on the anode side, and become oxygen molecules again. At this time, the electrons move in the opposite direction to the oxygen ions, thereby maintaining electrical neutrality.
[0005]
The technology for reforming hydrogen and synthesis gas (mixed gas of carbon monoxide and hydrogen) using hydrocarbon-containing gas as a raw material occupies an important position in petroleum and chemical processes, and contains hydrocarbons such as methane. Coupled with advances in technology for producing synthetic liquid fuels (Gas-To-Liquids: GTL) and fuel cell technology from raw gas as the raw material, the former is "effective use of unused natural gas resources" and "friendly to the global environment" In recent years, domestic and overseas research activities have been remarkably activated as “the supply of clean energy sources” and the latter “leading to clean vehicles”, “spreading distributed power sources”, and “use of clean energy” Yes.
[0006]
Under such circumstances, research for using a dense mixed conductive ceramic film not only for oxygen separation from oxygen-containing gas such as air but also as a reforming reactor has recently been accelerated. In this membrane reforming reactor, air is allowed to flow on one side (cathode side) of the membrane, a catalyst is disposed on the opposite side (anode side), and a hydrocarbon gas such as methane is allowed to flow to cause a partial oxidation reaction ( The oxygen partial pressure on the methane side is minimized, and as a result, the oxygen partial pressure difference, that is, the driving force for oxygen selective permeation can be maximized. Have. In addition, since partial oxidation reaction of methane or the like is performed simultaneously with air separation, that is, both oxygen separation and oxidation reaction can be performed at the same time in a single unit, there is a possibility of becoming a compact and inexpensive reactor.
[0007]
For the industrialization of the reactor, it is a major premise to obtain a sufficient oxygen permeation rate by a combination of a dense mixed conductive ceramic film and a hydrocarbon partial oxidation catalyst, which are basic constituent materials. The process of oxygen permeating through the ceramic film is a reaction in which oxygen molecules decompose into oxygen ions (cathode side reaction), diffusion movement depending on the chemical potential difference of oxygen ions, oxygen ions become oxygen atoms / oxygen molecules, and hydrocarbons The evaluation can be divided into three processes of oxidation reaction (anode side reaction). In order to improve the oxygen transmission rate per unit area, it is necessary to increase the speed of these three processes in a well-balanced manner, otherwise, any one of the above processes is rate-controlled, and a high oxygen transmission rate cannot be obtained as a whole. For example, in order to increase the diffusion transfer rate of oxygen ions in the film, it is effective to reduce the thickness of the dense mixed conductive ceramic material. On the other hand, the cathode side reaction and / or the anode is less than a certain thickness. The side reaction rate dominates the entire oxygen permeation process, and the effect of increasing the oxygen permeation rate due to the decrease in film thickness cannot be obtained. Therefore, in order to obtain a high oxygen transmission rate, it is important to improve the reaction rate on the cathode side and the anode side as well as reducing the thickness of the dense part.
[0008]
In the case of a reactor that obtains synthesis gas using oxygen-containing gas such as air and hydrocarbon gas as a raw material by a combination of a dense mixed conductive ceramic membrane and a hydrocarbon partial oxidation catalyst, an anode reaction occurs on the hydrocarbon gas side of the ceramic membrane. Oxygen atom oxygen atom / molecularization reactions and partial oxidation reactions of them with hydrocarbons occur. In such a case, the hydrocarbon gas side of the ceramic film is exposed to a high-level reducing atmosphere, and an object is to have a function to withstand the reducing atmosphere while promoting the anode reaction.
[0009]
In response to these problems, WO 98/41394 describes a dense mixed conductive ceramic film used for producing a synthesis gas by a partial oxidation reaction of a hydrocarbon gas such as methane, on the oxygen-containing gas side such as air of the film. A porous layer intended to promote the cathode reaction by increasing the surface area is formed using a dense ceramic material and a similar material, and on the opposite surface, a partial oxidation catalyst is adjoined to form a three-layer catalyst. Although a technique related to a ceramic composite material is disclosed, there is no specific description regarding the structure and material composition of a layer forming a partial oxidation catalyst.
[0010]
The present inventor has tried, as a partial oxidation catalyst layer, a catalyst layer in which a metal catalyst is supported on an oxide carrier (same as the porous reaction catalyst layer described in claim 5 of the present specification), a dense membrane. As the porous layer, a mixed conductive oxide (mixed conductive oxide having the composition described in claim 4 of the present specification) is used, methane gas is flowed to the catalyst layer side, and air is flowed to the porous layer side. The oxygen permeation rate (calculated from the partial oxidation reaction rate) of the three-layer structure material described in WO 98/41394 was measured, but the oxygen permeation rate was not large, and in order to obtain a high oxygen permeation rate in the material structure. I found that there is room for improvement.
[0011]
In JP-A-7-240115, the first surface of a film composed of a dense multi-component metal oxide layer is coated with a single-layer oxygen dissociation catalyst that promotes the cathode reaction, and the second surface is coated on the second surface. For the purpose of promoting the anode reaction and imparting mechanical strength to the dense membrane, a single-layered or multi-layered porous layer made of mixed conductive multi-component metal oxide or a material that does not exhibit mixed conductivity under the process operating conditions. Adjacent three-layer or four-layer ion transport membranes are disclosed. Japanese Patent Application Laid-Open No. 7-240115 discloses an invention that mainly focuses on a technique for separating oxygen from an oxygen-containing gas such as air. In paragraph 0015 and claim 46 of the same specification, an organic material containing hydrocarbons is disclosed. “Oxidation of compounds” is described as an application of the ion transport membrane.
[0012]
The ion transport membrane does not contain any reaction catalyst comprising a metal catalyst and a support in a porous layer or MC porous layer (a porous layer of mixed conductive multicomponent metal oxide). More specifically, the materials listed in the claims as forming the porous layer include multi-component metal oxides, metal alloys compatible with oxygen at high temperatures, metal oxide stabilized zirconia, ceria, electrons. Or, it is a substance such as alumina or magnesia that does not conduct oxygen, and does not include a reaction catalyst having a metal catalyst and a carrier. The material forming the MC porous layer is a multicomponent metal oxide, and does not include a reaction catalyst having a metal catalyst and a support. The invention of Japanese Patent Laid-Open No. 7-240115 should be considered as an invention that basically defines the structure of an ion transport film that promotes the cathode side and / or anode side reaction, and constitutes the ion transport film. Although a very wide range of materials has been claimed, the explanation for the reason is insufficient, so even those who are familiar with the technology can use specific materials based on the same specifications and simple tests. Selection is virtually impossible except in the cases described in the examples.
[0013]
The inventor has attempted to use a mixed conductive multicomponent metal oxide (mixed conductivity of the composition described in claim 4 of the present specification) as a dense film and a porous layer adjacent to the second surface of the film. The same oxide is used, and an oxide carrier-supported metal catalyst layer (same as the porous reaction catalyst layer described in claim 5 of the present specification) is used as the catalyst layer adjacent to the first surface of the membrane. As described in paragraph 0015, methane gas is allowed to flow on the second surface side and air is allowed to flow on the first surface side so that the ion transport membrane is in contact with the catalyzed surface of the membrane. The oxygen transmission rate (calculated from the oxidation reaction rate) was measured. As a result, it was found that the oxygen permeation rate was not large and there was room for significant improvement in the material structure. In addition, when the gas flow is changed and methane gas is flowed on the first surface side and air is flowed on the second surface side, it is the same as the measurement performed by the present inventor with respect to the above-mentioned WO 98/41394. As described above, there is room for improvement in the material structure.
[0014]
As described above, with respect to the membrane-type synthesis gas production technology for producing synthesis gas or the like from hydrocarbon gas and oxygen-containing gas using a catalyzed ceramic composite material, the cathode side and / or anode side reaction is generally promoted. Although specific membrane structures are disclosed, they promote both reactions while stably producing a hydrocarbon partial oxidation reaction and stably obtaining a sufficiently high oxygen permeation rate for practical use. For this reason, no specific technology relating to the catalyzed ceramic composite material has been disclosed, and there remains room for improvement.
[0015]
[Patent Document 1]
International publication pamphlet of WO 98/41394
[Patent Document 2]
Japanese Patent Laid-Open No. 7-240115
[0016]
[Problems to be solved by the invention]
The present invention is used in a membrane reactor for producing synthesis gas using an oxygen-containing gas and a hydrocarbon gas as raw materials, and stably generates a partial hydrocarbon oxidation reaction while promoting the cathode and anode reactions. It is an object of the present invention to provide a structure of a catalyzed ceramic composite material capable of obtaining a higher oxygen permeation rate than the technology and a specific composition of constituent materials.
[0017]
[Means for Solving the Problems]
The present invention has been made by combining a porous catalyst layer, a dense continuous layer, a porous intermediate catalyst layer, and a porous reaction catalyst layer so as to solve the above-mentioned problem, and forming a multilayer structure. Is as follows.
[0018]
(1)Ceramics used as a ceramic film of a ceramic film reactor for producing a synthesis gas from an oxygen-containing gas supplied to one side of the ceramic film and a hydrocarbon-containing gas supplied to the other side of the ceramic film In composite materials,The first surface of the selective oxygen permeable dense continuous layer comprising the mixed conductive oxide has no mixed conductive oxide.Arranged on the side to which the oxygen-containing gas is suppliedA porous catalyst layer is adjacent, and the second surface of the dense continuous layer has a mixed conductive oxide and / or a catalyst oxide having a combustion catalyst function.Arranged on the side to which the hydrocarbon-containing gas is supplied.The porous intermediate catalyst layer has a multilayer structure in which the porous intermediate catalyst layer is adjacent to a porous reaction catalyst layer having a metal catalyst and a carrier, and the porous reaction catalyst layer The main component of the support is MgO, and the metal catalyst of the porous reaction catalyst layer is one or more selected from Ni, Co, Ru, Rh, Pt, Pd, Ir, and Re as an active metal species. Supported metal catalystAny one or more of the dense continuous layer, the porous catalyst layer, and the porous intermediate catalyst layer have the mixed conductive oxide represented by the composition formula (1).A ceramic composite material catalyzed.
[Ln 1-ab A a Ba b ] [B x B ' y B " z ] O 3-δ Composition formula (1) (where Ln is a combination of one or more elements selected from lanthanoid elements,
A is Sr, Ca, or a combination of these elements,
B is a combination of one or more elements selected from Co, Fe, Cr, and Ga, and the sum of the number of moles of Cr and Ga is 0% or more and 20% or less with respect to the number of moles of all B elements,
B ′ is a combination of one or more elements selected from Nb, Ta, Ti, Zr, In, and Y, and includes at least one of Nb, Ta, In, and Y.
B ″ is a combination of one or more elements selected from Zn, Li, and Mg,
0.8 ≦ a + b ≦ 1,
b is 0.4 ≦ b ≦ 1.0 when B ′ is composed only of In, and 0.5 ≦ b ≦ 1.0 when B ′ is composed only of Y. 0.2 ≦ b ≦ 1.0 when composed only of In and Y, 0 ≦ b ≦ 1.0 when B ′ contains an element other than In and Y,
0 <x,
0 <y ≦ 0.5,
0 ≦ z ≦ 0.2,
0.98 ≦ x + y + z ≦ 1.02,
δ is a value determined so as to satisfy the charge neutrality condition. )
[0019]
(2) The catalyzed ceramic composite material according to (1), wherein the multilayer structure is formed as a coating layer on a porous support.
[0021]
(3The catalyst oxide having the combustion catalyst function includes one or more selected from Co, Fe, Mn, and Pd (1)Or (2)2. The catalyzed ceramic composite described in 1.
[0023]
(4) The mass per unit membrane area of the metal catalyst is 20 to 50 mg / cm2Said ()1)Any one of (3)2. The catalyzed ceramic composite described in 1.
[0024]
(5)Ceramics used as a ceramic film of a ceramic film reactor for producing a synthesis gas from an oxygen-containing gas supplied to one side of the ceramic film and a hydrocarbon-containing gas supplied to the other side of the ceramic film In the manufacturing method of the composite material,On the first and second surfaces of the dense continuous layer having the mixed conductive oxide represented by the composition formula (1), the mixed conductivity represented by the composition formula (1) with a particle size of 10 μm or less. The oxide fine powder mixed with an organic solvent to form a slurry is applied and dried, and baked at 950 ° C to 1500 ° C.Arranged on the oxygen supply gas supply sidePorous catalyst layer andIt is arranged on the side where the hydrocarbon-containing gas is suppliedA porous intermediate catalyst layer, and on the porous intermediate catalyst layer, one or more selected from Ni, Co, Ru, Rh, Pt, Pd, Ir, and Re as a carrier mainly composed of MgO The fine powder of the metal-supported catalyst supporting the active metal species is added to the fine powder of the porous intermediate catalyst layer, mixed with an organic solvent, and applied to a slurry, and dried, and the temperature is 950 ° C. or higher and 1500 ° C. or lower. A method for producing a catalyzed ceramic composite material, characterized by baking with
[Ln1-abAaBab] [BxB ’yB "z] O3-δ Composition formula (1) wherein Ln is a combination of one or more elements selected from lanthanoid elements,
A is Sr, Ca, or a combination of these elements,
B is a combination of one or more elements selected from Co, Fe, Cr, and Ga, and the sum of the number of moles of Cr and Ga is 0% or more and 20% or less with respect to the number of moles of all B elements,
B ′ is a combination of one or more elements selected from Nb, Ta, Ti, Zr, In, and Y, and includes at least one of Nb, Ta, In, and Y.
B ″ is a combination of one or more elements selected from Zn, Li, and Mg,
0.8 ≦ a + b ≦ 1,
b is 0.4 ≦ b ≦ 1.0 when B ′ is composed only of In, and 0.5 ≦ b ≦ 1.0 when B ′ is composed only of Y. 0.2 ≦ b ≦ 1.0 when composed only of In and Y, 0 ≦ b ≦ 1.0 when B ′ contains an element other than In and Y,
0 <x,
0 <y ≦ 0.5,
0 ≦ z ≦ 0.2,
0.98 ≦ x + y + z ≦ 1.02,
δ is a value determined so as to satisfy the charge neutrality condition.
[0025]
(6) (1) to (4A ceramic membrane reactor comprising the catalyzed ceramic composite material according to any one of the above.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the catalyzed ceramic composite material of the present invention will be described.
[0027]
As described above, in order to improve the oxygen permeation rate (synthesis gas production rate) per unit area, it is necessary to improve the three processes of the cathode side reaction, oxygen ion diffusion transfer, and anode side reaction in a balanced manner.
[0028]
The present inventor firstly increases the reaction field, that is, the surface area obtained by adding a porous catalyst layer, which is generally known as a cathode side reaction promotion method in which oxygen molecules in an oxygen-containing gas are converted into oxygen ions. Focused on the increase. By adjoining the first surface of the dense continuous layer with a porous catalyst layer comprising a mixed conductive oxide, significant acceleration of the cathode reaction is achieved. As a material for the porous catalyst layer of the present invention, a mixed conductive perovskite oxide having high oxygen permeability is suitable. As a result of eager search for a material having a high oxygen permeability for the material of the porous catalyst layer, the inventor has a composition represented by the following formula (1):
[Ln1-abAaBab] [BxB ’yB "z] O3- δ (1)
(However, Ln is one or a combination of two or more elements selected from lanthanoid elements. A is Sr, Ca, or a combination of these elements. B is Co, Fe, Cr, and In a combination of one or more elements selected from Ga, the sum of the number of moles of Cr and Ga is 0% or more and 20% or less with respect to the number of moles of all B elements. A combination of one or more elements selected from Nb, Ta, Ti, Zr, In, and Y, including at least one element of Nb, Ta, In, and Y. B ″ is Zn, Li, Mg Or a combination of two or more elements selected from: 0.8 ≦ a + b ≦ 1, and b is 0.4 ≦ b ≦ 1.0 when B ′ is composed only of In. , B ′ is composed only of Y, 0.5 ≦ b ≦ 1.0 When B ′ is composed only of In and Y, 0.2 ≦ b ≦ 1.0, 0.98 ≦ x + y + z ≦ 1.02, and 0 <x, 0 <y ≦ 0.5, 0 ≦ z ≦ 0.2 (δ is a value determined to satisfy the charge neutrality condition.)
The material which consists of perovskite type oxide represented by these was discovered.
[0029]
For increasing the oxygen ion diffusion rate in the dense continuous layer, as is generally known, it is appropriate to use a perovskite oxide having a high ion conductivity as a material. As a specific material, the present inventor has high ionic conductivity and compatibility with the porous catalyst layer material and the porous intermediate catalyst layer material (such as no peeling during baking of the porous layer). As a result, the inventors have found that a material similar to the porous catalyst layer, that is, a material made of a perovskite oxide represented by the above formula (1) is suitable.
[0030]
On the other hand, regarding the method for promoting the anode-side reaction in which hydrocarbon gas such as methane is oxidized, the present inventor does not adjoin a porous reaction catalyst layer known in the art to a dense continuous layer, but a mixed conductive oxidation. A structure in which a porous intermediate catalyst layer made of a product and / or a catalyst oxide having a combustion catalyst function is adjacent to a dense continuous layer, and the porous reaction catalyst layer is adjacent to the porous intermediate catalyst layer via the porous intermediate catalyst layer. It was newly found that it is extremely effective for promoting the reaction.
[0031]
The material of the porous intermediate catalyst layer of the present invention has high reduction resistance and high oxygen-permeable mixed conductivity so that the anode side reaction can be stably promoted even in a reducing atmosphere such as hydrocarbons. A suitable oxide is suitable. As a result of earnest search for perovskite type oxides having mixed conductivity, high oxygen permeability and reduction resistance for use in the porous intermediate catalyst layer, the inventor has found that the porous catalyst layer or the dense continuous layer It has been found that the same composition material as the layer, that is, the perovskite oxide represented by the above formula (1) satisfies these conditions. Furthermore, the porous intermediate catalyst layer of the present invention has a catalyst oxide that does not have mixed conductivity but has a combustion catalyst function, that is, an oxidation containing one or more of Co, Fe, Mn, and Pd. Things are also effective. In the porous intermediate catalyst layer of the present invention, both of these mixed conductive oxides and catalyst oxides may be used simultaneously, or only one of them may be used.
[0032]
In addition, regarding the material forming the porous reaction catalyst layer, the present inventor considered that the high temperature operation was not performed, and the present inventor did not react with the perovskite type oxide constituting the porous intermediate catalyst layer, and As a result of diligent search for materials having compatibility (such as no peeling during baking), MgO, which has extremely low reactivity, is suitable as a catalyst carrier used in the porous reaction catalyst layer, and Ni, Co as reaction catalysts. It has been found that it is preferable to support a support with one or more active metal species selected from Ru, Rh, Pt, Pd, Ir, and Re.
[0033]
In the case where there is no porous reaction catalyst layer but only a porous intermediate catalyst layer having a mixed conductive oxide, a complete oxidation reaction of hydrocarbon is promoted as an anode side reaction. It is not suitable for the purpose. Therefore, this case is not included in the scope of the present invention.
[0034]
In the present invention, the relationship between what the inventors have devised and the prior art will be described.
[0035]
The cathode-side porous catalyst layer and dense continuous layer (dense membrane part) are structurally similar to the prior art, but in the present invention, a material suitable for this part is specifically presented. Yes. Next, regarding the configuration on the anode side, this portion is greatly different from that of the prior art. The inventor divided the reaction on the anode side into a hydrocarbon complete oxidation reaction and a complete oxidation reaction product reforming reaction, and synthesized them by a method in which these reactions proceed sequentially in two adjacent layers. Invented a new strategy of generating gas. By making the reaction on the anode side into two stages, it becomes possible for the first time to perform the hydrocarbon partial oxidation reaction stably while obtaining a high oxygen transmission rate. The complete oxidation reaction of hydrocarbon is performed by the mixed conductive porous intermediate catalyst layer.
[0036]
A mixed conductive oxide is suitable as a catalyst for rapidly proceeding with this complete oxidation reaction. This is because the same material advances an anodic reaction in which oxygen ions diffused through the dense continuous layer are oxygen atoms on the surface of the same material, and the oxygen atoms immediately absorb hydrocarbon molecules adsorbed on the catalyst surface. This is because it has the property of oxidative decomposition.
[0037]
Making the porous intermediate catalyst layer porous increases the reaction surface area and increases the rate of complete oxidation reaction, and at the same time, exchange of raw material gases such as hydrocarbons, and water vapor and carbon dioxide as reaction products is performed quickly. It is essential to be
[0038]
For the reforming reaction (syngas production reaction) of hydrocarbons and the like with water vapor and carbon dioxide gas, it is selected from Ni, Co, Ru, Rh, Pt, Pd, Ir, Re known as reforming reaction catalysts 1 It is sufficient to use a species or two or more active metal species, but the reaction surface area is increased to increase the reaction rate, and various gas species such as hydrocarbon, raw material gas, water vapor, carbon dioxide, synthesis gas, etc. It is necessary to make a porous reaction catalyst layer supported on a carrier so that the exchange can be performed quickly. The present inventor has not only invented the above new structure for the anode side reaction, but specifically presents a material suitable for this site.
[0039]
The perovskite oxide suitably used for the catalyzed ceramic composite of the present invention will be described in more detail.
[0040]
Perovskite oxides have the general formula ABOThreeA large number of compounds having a perovskite oxide structure have been reported so far, which consist of a structure having a closely packed lattice of (A and B are metal ions). If the conditions for the physicochemical and crystallographic factors of the metal ions A and B are met, ABOThreeCrystallize in the form of
[0041]
Here, if the sum of the valences of the metal ions is the sum of the valences of the oxygen ions, that is, + (plus) hexavalence that cancels out the-(minus) hexavalence, oxygen vacancies are not generated. When the sum of the numbers is less than 6 valences, oxygen ions are removed to maintain electrical equilibrium, creating oxygen vacancies, which are believed to provide oxygen ion conductivity. On the other hand, the electronic conductivity is generally considered to be due to hopping conduction caused by a change in the valence of the transition element between the bond between the transition element and oxygen. Therefore, in the perovskite oxide having mixed conductivity, a transition element is arranged at the B site, and a combination of a lanthanoid element and an alkaline earth element that causes oxygen vacancies at the A site, or an alkaline earth metal alone Placed, and these impart electron and ionic conductivity. Depending on the combination of these A-site elements and B-site elements, different mixed conductivity or reduction resistance is exhibited.
[0042]
The present invention focuses on Fe that has a relatively high reduction resistance while exhibiting high oxygen ion conductivity when disposed at the B site for the porous intermediate catalyst layer material. With regard to the porous catalyst layer material, focusing on Co that exhibits a very large oxygen ion conductivity when arranged at the B site, various combinations of the A site element and the B site element containing Fe or Co are energetic. It was made as a result of study.
[0043]
In the constituent element of B in the formula (1), the sum of the number of moles of Cr and Ga is limited to 20% or less with respect to the number of moles of all B elements. The content of Cr and Ga exceeds 20%. This is because the oxygen ion conductivity decreases. When B 'is only In, only Y, or only In and Y, the range of b is limited because the stability of the perovskite structure decreases when b is outside these ranges. When B ′ contains an element other than In and Y, the perovskite structure is stable in the range of 0 ≦ b ≦ 1.0. The reason why the range of a + b is limited is that, if a + b is out of this range, the oxygen ion conductivity decreases. The reason why the range of y is limited to 0.5 or less is that when Nb, Ta, Ti, Zr, In, and Y are contained beyond this range, the oxygen ion conductivity decreases. The reason for limiting the range of z to 0.2 or less is that if Zn, Li, or Mg is contained beyond this range, oxygen ion conductivity is lowered or the stability of the perovskite structure is lowered. It is. Furthermore, the reason why the range of x + y + z is limited is that, if x + y + z is out of this range, there arises a problem that the oxygen ion conductivity is lowered. Note that the mixed conductive oxides of the dense continuous layer material, the porous catalyst material, and the porous intermediate catalyst layer may not have the same composition.
[0044]
In the present invention, a multilayer structure comprising a porous catalyst layer, a dense continuous layer, a porous intermediate catalyst layer, and a porous reaction catalyst layer may be formed as a coating layer on the porous support. With this structure, since the mechanical strength can be increased, the resistance when the pressures of the source gas on the cathode side and the anode side are different and there is a difference in the total pressure through the dense continuous layer is increased. The porous support material may be anything as long as it has mechanical strength and is compatible with the multilayer structure. For example, it may be a mixed conductive oxide. Further, the porous catalyst layer may be thickened to have a function as a porous support.
[0045]
The dense continuous layer according to the present invention has a thickness of 1 μm to 2 mm, preferably 10 μm to 1.5 mm, and more preferably 30 μm to 1 mm. If the dense continuous layer is too thick, the oxygen permeation rate cannot be increased. Conversely, if the dense continuous layer is too thin, the mechanical reliability is poor. Therefore, the thickness has an appropriate range as described above.
[0046]
The thicknesses of the porous intermediate catalyst layer and the porous catalyst layer according to the present invention are in the range of 1 μm to 1 mm and 1 μm to 5 mm, respectively. The porosity of the porous intermediate catalyst layer and the porous catalyst layer is in the range of 20% to 80%, preferably in the range of 30% to 60%. If the porosity is less than 20%, the movement of the raw material gas and the reaction product is hindered, and the oxygen transmission rate (synthesis gas production rate) does not increase. On the other hand, if it exceeds 80%, the mechanical reliability is poor.
[0047]
With respect to the porous reaction catalyst layer material according to the present invention, as described above, Ni, Co, Ru, Rh, Pt, active in reforming hydrocarbons with water vapor and carbon dioxide on a carrier mainly composed of MgO. A material carrying one or more active metal species selected from Pd, Ir, and Re is desirable from the viewpoint of activity and compatibility with the porous intermediate catalyst layer. The porous reaction catalyst layer transfers not only the hydrocarbon reforming but also the heat generated in the porous intermediate catalyst layer where the complete oxidation reaction of hydrocarbons occurs to the porous reaction catalyst layer (where endothermic reaction occurs) By doing so, it plays an important role of avoiding hot spot formation that leads to material degradation.
[0048]
Next, the manufacturing method of this invention material is demonstrated.
[0049]
The raw material of the ceramic material constituting the porous catalyst layer, the dense continuous layer, the porous intermediate catalyst layer, and the porous reaction catalyst layer according to the present invention uses metal salts such as metal oxides and carbonates. Are prepared by mixing and baking. For the preparation of the powder raw material, a coprecipitation method, a metal alkoxide method (sol-gel method), or a preparation method equivalent thereto may be used. The mixed raw material powder is calcined at 800 ° C. or higher and 1500 ° C. or lower.
[0050]
The material constituting the dense continuous layer is formed after the calcined sample is finely pulverized and uniformly mixed. Molding was performed by applying any suitable ceramic manufacturing technology such as CIP (cold isostatic pressing), HIP (hot isostatic pressing), mold press, injection molding, slip casting, extrusion molding, etc. The sample is fired at 1050 ° C. or higher and 1500 ° C. or lower.
[0051]
Unlike the production of a dense continuous layer, the porous catalyst layer and the porous intermediate catalyst layer material are prepared at 1050 ° C. or more and 1500 ° C. or less without forming after the raw material is prepared, mixed, calcined, and pulverized. The main firing is performed. Here, if the raw materials are uniformly mixed, the intermediate calcination may be omitted and the main calcination may be performed. The temperature range of the main baking is set to 1050 ° C. or more and 1500 ° C. or less which becomes a perovskite structure that exhibits mixed conductivity. The calcined sample is pulverized by a suitable method such as a ball mill. The particle size of the pulverized powder is desirably 10 μm or less for the reason described later.
[0052]
The porous catalyst layer and the porous intermediate catalyst layer are formed by mixing the pulverized powder with an organic solvent or the like to form a slurry, which is coated so as to cover the surface of the dense continuous layer, dried and then baked (fired). Do. In general, the smaller the particle diameter of the powder to be applied is, or the thinner the powder is applied, the more uniformly the film surface can be adhered. Specifically, the particle size of the powder is desirably 10 μm or less. In addition to the above, as a means for forming the porous intermediate catalyst layer, a CVD (chemical vapor deposition) method, an electrophoresis method, a sol-gel method, or any other suitable method can be used.
[0053]
The porous layer formed by these methods is fired so that the porous layer and the dense continuous layer are firmly joined to ensure continuity regarding the mixed conductivity at the interface with the dense continuous layer. . As the firing temperature, a suitable temperature at which strong bonding can be obtained at a temperature lower than the melting point of the low material among the materials forming the porous layer and the dense continuous layer is selected. The material specifically presented in the present invention is preferable since a strong bonding can be obtained at a baking temperature of 950 ° C. or higher and 1500 ° C. or lower.
[0054]
The catalyst material constituting the porous reaction catalyst layer is one or two or more active metals selected from Ni, Co, Ru, Rh, Pt, Pd, Ir, and Re on a support mainly composed of magnesia. It is desirable to carry seeds. As the catalyst preparation method, any method such as an impregnation support method, an equilibrium adsorption method, a coprecipitation method, and the like can be selected. The supported amount of the active metal species is 3 to 30 mol% for Ni and Co, 0.1 to 10 mass% for Ru, and 0.01 for Rh, Pt, Pd, Ir and Re with respect to the support. -3 mass% is desirable, and these may be combined. In order to highly disperse the active metal species, Ni or Co may be dissolved in magnesia. In this case, a coprecipitation method or a ceramic method is used.
[0055]
The porous reaction catalyst layer is prepared by adding 0.1% by mass or more and 30% by mass or less of the material fine powder of the porous intermediate catalyst layer to the finely pulverized powder of the prepared catalyst. It is formed as a slurry by coating the porous intermediate catalyst layer with coating, drying and baking (firing). Generally, the smaller the particle diameter of the applied powder is, or the thinner it is applied, the more uniformly it can be attached to the film surface. Specifically, it is desirable that the particle size of the powder is 0.5 μm or more and 10 μm or less. The firing temperature should be at least 50 ° C. higher than the actual operating temperature of the membrane reactor, and should be selected in a temperature range lower than the melting point of the ceramic composite material, and should be baked in air. Is desirable. In the case of the materials specifically presented in the present invention, strong bonding can be obtained at a baking temperature of 950 ° C. or higher and 1500 ° C. or lower. Moreover, the catalyst mass per unit membrane area is 20-50 mg / cm.2Is preferable. In addition, depending on the operating conditions of the membrane reactor, there is a method in which the reaction catalyst is sized and arranged without being baked on the porous intermediate catalyst layer. Further, there is a method of combining the slurry coat and the sized catalyst arrangement.
[0056]
【Example】
Hereinafter, the present invention will be described with reference to examples. In addition, this invention is not limited to an Example.
[0057]
Example 1
SrCO with a purity of 99% or moreThree, Fe2OThree, And Nb2OFiveWere weighed so that the molar ratio Sr: Fe: Nb = 1: 0.9: 0.1, and wet-mixed for 2 hours using a planetary ball mill. The obtained raw material powder was put in an alumina crucible and fired in air at 1350 ° C. for 5 hours to obtain a composite oxide. The room temperature powder X-ray diffraction measurement result of this composite oxide shows that the main component is a cubic perovskite structure, and the composition is SrFe0.9Nb0.1O3- δIt was confirmed that the composite oxide represented by The composite oxide was powdered with an automatic mortar to a particle size of 10 μm or less to obtain a porous intermediate catalyst layer material.
[0058]
Next, BaCO having a purity of 99% or moreThree, SrCOThree, CoO, and Fe2OThreeWere weighed so that the molar ratio Ba: Sr: Co: Fe = 0.5: 0.5: 0.8: 0.2 and wet-mixed for 2 hours using a planetary ball mill. The obtained raw material powder was put in an alumina crucible and calcined in the atmosphere at a temperature of 950 ° C. for 20 hours to obtain a composite oxide. This composite oxide was wet pulverized with a planetary ball mill for 2 hours, and then 3 g of this powder was formed into a disk shape at 25 MPa in a mold having a diameter of 20 mm. The molded body was put in an airtight bag, deaerated and evacuated, and then subjected to CIP for 15 minutes while being pressurized to 200 MPa, and then subjected to main firing at a temperature of 1130 ° C. for 5 hours in a relative density of 95%. The above-mentioned densified sintered body was obtained. The room temperature powder X-ray diffraction measurement result of this sintered body shows that the main component is a cubic perovskite structure, and the composition is Ba0.5Sr0.5Co0.8Fe0.2O3- δIt was confirmed that the composite oxide represented by Both surfaces of this sintered body were ground and polished to form a disk shape having a diameter of 12 mm and a thickness of 0.7 mm, and this was used as a dense continuous layer.
[0059]
Subsequently, the composition obtained by the same method is Ba.0.5Sr0.5Co0.8Fe0.2O3- δWas pulverized to a particle size of 10 μm or less to obtain a porous catalyst layer material. This was suspended in an organic solvent to form a slurry and applied to the first surface of the disk-shaped dense continuous layer. Further, the porous intermediate layer material was similarly made into a slurry and applied to the second surface of the dense continuous layer. This was dried at 120 ° C. for 5 minutes and then calcined in air at 1050 ° C. for 5 hours to obtain a porous catalyst layer and a porous intermediate catalyst layer firmly bonded to the dense continuous layer. At this time, the thicknesses of the porous catalyst layer and the porous intermediate catalyst layer were 0.3 and 0.2 mm, respectively.
[0060]
On the porous intermediate catalyst layer, 28 mg of a powder of a hydrocarbon reforming catalyst having a particle size of 10 μm or less in which 10 mol% of Ni is dissolved in Mg in magnesia is added to 5 mg of the material powder of the porous intermediate catalyst layer. In addition, the well-mixed mixture was suspended in an organic solvent and slurry coated. This was dried at 120 ° C. for 5 minutes, and then calcined in air at 1050 ° C. for 5 hours to join the hydrocarbon reforming catalyst layer (porous reaction catalyst layer) to the porous intermediate catalyst layer, and the catalyst of the present invention. The obtained ceramic composite material was obtained and subjected to an oxygen permeation (synthesis gas production) experiment.
[0061]
The experiment was carried out at a temperature of 900 ° C. and a pressure of 10 atm while the catalyzed ceramic composite material was sandwiched between two mullite tubes via a silver ring and the cathode and anode sides were kept airtight. . Regarding the source gas, air was supplied to the cathode side at 200 cc / min, and methane was supplied to the anode side at 40 cc / min. As a result of measuring the anode side outlet gas with a gas chromatograph and calculating the oxygen transmission rate in a stable state from the air side to the methane side by element balance, 21 cc / min / cm2Met. At this time, the methane reaction conversion rate is 58%, CO selectivity (CO and CO2CO ratio is 80%, H2The / CO ratio was 1.8.
[0062]
During the experiment, no cracks were generated in the dense continuous layer of the catalyzed ceramic composite of the present invention, and no signs of destruction over time were observed. Moreover, except for the period immediately after the start of the experiment, the catalyzed ceramic composite of the present invention showed a stable oxygen permeation (synthesis gas generation) rate, and no signs of deterioration were observed.
[0063]
(Example 2)
Using a disk-shaped composite composed of a porous catalyst layer, a dense continuous layer, and a porous intermediate catalyst layer produced by the same method and conditions as in Example 1, magnesia was impregnated with 5 mol% of Ni with respect to Mg. A hydrogen reforming catalyst having a particle diameter of 10 μm or less and 5 mg of the porous intermediate catalyst layer material fine powder added thereto and sufficiently mixed are suspended in an organic solvent, and this is suspended in the porous intermediate catalyst layer. The slurry was coated on top. This was dried at 120 ° C. for 5 minutes, and then calcined in air at 1050 ° C. for 5 hours to join the hydrocarbon reforming catalyst layer (porous reaction catalyst layer) to the porous intermediate catalyst layer, and the catalyst of the present invention. A ceramic composite material was obtained.
[0064]
In the oxygen permeation experiment, 900 mg of a hydrocarbon reforming catalyst in which 2% by mass of Ru was impregnated and supported on magnesia sized to 20/40 mesh was disposed on the porous reaction catalyst layer of the composite material, and The method and conditions were the same as those shown in Example 1 except that the pressure was 1 atm. As a result of calculating the oxygen transmission rate in a stable state, 25 cc / min / cm2Met. At this time, the methane reaction conversion rate is 83%, CO selectivity (CO and CO2CO ratio is 86%, H2The / CO ratio was 1.9.
[0065]
During the experiment, no cracks were generated in the dense continuous layer of the catalyzed ceramic composite of the present invention, and no signs of destruction over time were observed. Moreover, except for the period immediately after the start of the experiment, the catalyzed ceramic composite of the present invention showed a stable oxygen permeation (synthesis gas generation) rate, and no signs of deterioration were observed.
[0066]
(Example 3)
When the catalyst and ceramic composite material of the present invention shown in Table 1 was produced under the same method and conditions as in Example 1, and the oxygen permeation (synthesis gas production) characteristics were evaluated under the same method and conditions as in Example 1, 20cc / min / cm for everything2The above oxygen transmission rate was obtained. Moreover, like the result of Example 1, a stable oxygen permeation (synthesis gas production) rate was exhibited, and no signs of deterioration and destruction over time were observed.
[Table 1]
(Comparative Example 1)
After preparing a catalyzed ceramic composite comprising a porous catalyst layer and a dense continuous layer in the same manner and conditions as in Example 1, magnesia sized to 20/40 mesh on the dense continuous layer The hydrocarbon reforming catalyst 900 mg impregnated and supported with 2% by mass of Ru was placed on the catalyst and subjected to an oxygen permeation experiment.
[0068]
The experiment was performed under the same method and conditions as in Example 1. As a result of calculating the oxygen transmission rate in a stable state, 18 cc / min / cm was obtained.2Met. At this time, the methane reaction conversion rate is 76%, CO selectivity (CO and CO2CO ratio is 96%, H2The / CO ratio was 2.0.
[0069]
(Comparative Example 2)
As an intermediate porous catalyst layer material, Ba 0.5 Sr 0.5 Co 0.8 Fe 0.2 O 3-δ A catalyzed ceramic composite material comprising a porous catalyst layer, a dense continuous layer and a porous intermediate catalyst layer was produced in the same manner and under the same conditions as in Example 1 except that the composite oxide represented by Thereafter, 900 mg of a hydrocarbon reforming catalyst in which 2 mass% of Ru was impregnated and supported on a porous intermediate catalyst layer and sized to 20/40 mesh was placed and subjected to an oxygen permeation experiment.
[0070]
The experiment was performed under the same method and conditions as in Example 1, and about 23 cc / min / cm after several hours from the start of the experiment. 2 However, the oxygen transmission rate decreased with time, and a stable oxygen transmission rate was not obtained.
[0071]
(Comparative example3)
On the porous intermediate catalyst layer of a disk-shaped composite comprising a porous catalyst layer, a dense continuous layer, and a porous intermediate catalyst layer prepared by the same method and conditions as in Example 1, 2 on an alumina (α-type) support. A slurry obtained by suspending 30 mg of a hydrocarbon reforming catalyst impregnated and supported by mass% Ru with a particle diameter of 10 μm or less in an organic solvent was slurry coated. This was dried at 120 ° C. for 5 minutes and then calcined in air at 1050 ° C. for 5 hours to obtain a hydrocarbon reforming catalyst layer bonded to the porous intermediate catalyst layer, which was subjected to an oxygen permeation experiment. The experiment was conducted under the same method and conditions as in Example 1 except that the pressure was 10 atm. After several hours from the start of the experiment, about 20 cc / min / cm.2However, the oxygen transmission rate decreased with time, and a stable oxygen transmission rate was not obtained.
[0072]
【The invention's effect】
According to the present invention, a high-performance diaphragm member that stably obtains a high oxygen permeation rate when selectively transporting an oxygen component in an oxygen-containing gas can be obtained. It can be suitably used for a membrane reactor, etc., and contributes to the compactness that leads to high performance and low cost of these apparatuses.
[Brief description of the drawings]
FIG. 1 is a structural conceptual diagram of a multilayer catalyst comprising a porous catalyst layer, a dense continuous layer, a porous intermediate catalyst layer, and a reaction catalyst layer of the present invention, and a ceramic composite material.
Claims (6)
［Ｌｎ １−ａ−ｂ Ａ ａ Ｂａ ｂ ］［Ｂ ｘ Ｂ’ ｙ Ｂ” ｚ ］Ｏ ３−δ 組成式（１）（ここで、Ｌｎは、ランタノイド元素から選ばれる１種または２種以上の元素の組み合わせ、
Ａは、Ｓｒ、Ｃａ、またはこれらの元素の組み合わせ、
Ｂは、Ｃｏ、Ｆｅ、Ｃｒ、及びＧａから選ばれる１種または２種以上の元素の組み合わせで、ＣｒとＧａのモル数の和が全Ｂ元素のモル数に対し０％以上２０％以下、
Ｂ’は、Ｎｂ、Ｔａ、Ｔｉ、Ｚｒ、Ｉｎ、及びＹから選ばれる１種または２種以上の元素の組み合わせで、Ｎｂ、Ｔａ、Ｉｎ、Ｙの少なくとも１種を含む、
Ｂ”は、Ｚｎ、Ｌｉ、Ｍｇから選ばれる１種または２種以上の元素の組み合わせ、
０．８≦ａ＋ｂ≦１、
ｂは、Ｂ’がＩｎのみで構成される場合には０．４≦ｂ≦１．０、Ｂ’がＹのみで構成される場合には０．５≦ｂ≦１．０、Ｂ’がＩｎおよびＹのみで構成される場合には０．２≦ｂ≦１．０、Ｂ’がＩｎ、Ｙ以外の元素を含む場合には０≦ｂ≦１．０、
０＜ｘ、
０＜ｙ≦０．５、
０≦ｚ≦０．２、
０．９８≦ｘ＋ｙ＋ｚ≦１．０２、
δは、電荷中性条件を満たすように決まる値である。） Ceramics used as a ceramic film of a ceramic film reactor for producing a synthesis gas from an oxygen-containing gas supplied to one side of the ceramic film and a hydrocarbon-containing gas supplied to the other side of the ceramic film in the composite material, the first surface of the made a mixed conducting oxide selective oxygen permeable dense continuous layer, Ri na a mixed conducting oxide, the oxygen-containing gas is supplied side A porous intermediate catalyst layer comprising a mixed conductive oxide and / or a catalyst oxide having a combustion catalyst function on the second surface of the dense continuous layer. There adjacent further multi the porosifying middle catalyst layer, Ri na a metal catalyst and a carrier, a multilayer structure in which the hydrocarbon-containing porous catalyst layer gas Ru is disposed on the side supplied to adjacent The multi The main component of the support of the porous reaction catalyst layer is MgO, and the metal catalyst of the porous reaction catalyst layer is one or more selected from Ni, Co, Ru, Rh, Pt, Pd, Ir, Re supported metal catalysts der to active metal species is, the dense continuous layer, a porous catalyst layer, and mixed conducting oxide represented by any one or more formula porous intermediate catalyst layer (1) catalyzed characterized Rukoto such a the ceramic composite.
[Ln 1-a-b A a Ba b] [B x B 'y B "z] O 3-δ composition formula (1) (where, Ln is one or more selected from lanthanoids Combination of elements,
A is Sr, Ca, or a combination of these elements,
B is a combination of one or more elements selected from Co, Fe, Cr, and Ga, and the sum of the number of moles of Cr and Ga is 0% or more and 20% or less with respect to the number of moles of all B elements,
B ′ is a combination of one or more elements selected from Nb, Ta, Ti, Zr, In, and Y, and includes at least one of Nb, Ta, In, and Y.
B ″ is a combination of one or more elements selected from Zn, Li, and Mg,
0.8 ≦ a + b ≦ 1,
b is 0.4 ≦ b ≦ 1.0 when B ′ is composed only of In, and 0.5 ≦ b ≦ 1.0 when B ′ is composed only of Y. 0.2 ≦ b ≦ 1.0 when composed only of In and Y, 0 ≦ b ≦ 1.0 when B ′ contains an element other than In and Y,
0 <x,
0 <y ≦ 0.5,
0 ≦ z ≦ 0.2,
0.98 ≦ x + y + z ≦ 1.02,
δ is a value determined so as to satisfy the charge neutrality condition. )
［Ｌｎ１−ａ−ｂＡａＢａｂ］［ＢｘＢ’ｙＢ”ｚ］Ｏ３−δ 組成式（１）ここで、Ｌｎは、ランタノイド元素から選ばれる１種または２種以上の元素の組み合わせ、
Ａは、Ｓｒ、Ｃａ、またはこれらの元素の組み合わせ、
Ｂは、Ｃｏ、Ｆｅ、Ｃｒ、及びＧａから選ばれる１種または２種以上の元素の組み合わせで、ＣｒとＧａのモル数の和が全Ｂ元素のモル数に対し０％以上２０％以下、
Ｂ’は、Ｎｂ、Ｔａ、Ｔｉ、Ｚｒ、Ｉｎ、及びＹから選ばれる１種または２種以上の元素の組み合わせで、Ｎｂ、Ｔａ、Ｉｎ、Ｙの少なくとも１種を含む、
Ｂ”は、Ｚｎ、Ｌｉ、Ｍｇから選ばれる１種または２種以上の元素の組み合わせ、
０．８≦ａ＋ｂ≦１、
ｂは、Ｂ’がＩｎのみで構成される場合には０．４≦ｂ≦１．０、Ｂ’がＹのみで構成される場合には０．５≦ｂ≦１．０、Ｂ’がＩｎおよびＹのみで構成される場合には０．２≦ｂ≦１．０、Ｂ’がＩｎ、Ｙ以外の元素を含む場合には０≦ｂ≦１．０、
０＜ｘ、
０＜ｙ≦０．５、
０≦ｚ≦０．２、
０．９８≦ｘ＋ｙ＋ｚ≦１．０２、
δは、電荷中性条件を満たすように決まる値である。 Ceramics used as a ceramic film of a ceramic film reactor for producing a synthesis gas from an oxygen-containing gas supplied to one side of the ceramic film and a hydrocarbon-containing gas supplied to the other side of the ceramic film In the method for producing a composite material, the first surface and the second surface of the dense continuous layer having the mixed conductive oxide represented by the composition formula (1) have a particle size of 10 μm or less and the composition formula (1). The mixed conductive oxide fine powder represented by the above is mixed with an organic solvent to form a slurry, applied and dried, baked at 950 ° C. to 1500 ° C., and supplied with the oxygen supply gas. porous catalyst layer and the hydrocarbon-containing gas are arranged as a porous intermediate catalyst layer disposed on the side supplied, further to the porous middle catalyst layer, composed mainly of MgO to A fine powder of a metal-supported catalyst in which one or more active metal species selected from Ni, Co, Ru, Rh, Pt, Pd, Ir, and Re are supported on the body is added to the fine powder of the porous intermediate catalyst layer. A method for producing a catalyzed ceramic composite comprising adding powder, mixing an organic solvent into a slurry, applying and drying, and baking at 950 ° C to 1500 ° C.
[Ln 1-a-b A a Ba b] [B x B 'y B "z] O 3-δ composition formula (1) where, Ln is one or more elements selected from lanthanoids A combination of
A is Sr, Ca, or a combination of these elements,
B is a combination of one or more elements selected from Co, Fe, Cr, and Ga, and the sum of the number of moles of Cr and Ga is 0% or more and 20% or less with respect to the number of moles of all B elements,
B ′ is a combination of one or more elements selected from Nb, Ta, Ti, Zr, In, and Y, and includes at least one of Nb, Ta, In, and Y.
B ″ is a combination of one or more elements selected from Zn, Li, and Mg,
0.8 ≦ a + b ≦ 1,
b is 0.4 ≦ b ≦ 1.0 when B ′ is composed only of In, and 0.5 ≦ b ≦ 1.0 when B ′ is composed only of Y. 0.2 ≦ b ≦ 1.0 when composed only of In and Y, 0 ≦ b ≦ 1.0 when B ′ contains an element other than In and Y,
0 <x,
0 <y ≦ 0.5,
0 ≦ z ≦ 0.2,
0.98 ≦ x + y + z ≦ 1.02,
δ is a value determined so as to satisfy the charge neutrality condition.
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| JP2005270895A (en) * | 2004-03-26 | 2005-10-06 | Noritake Co Ltd | Oxidation reaction apparatus and its use |
| JP2006082039A (en) * | 2004-09-17 | 2006-03-30 | Noritake Co Ltd | Oxygen separation membrane element, its manufacturing method, oxygen manufacturing method, and reactor |
| AU2005294472A1 (en) * | 2004-10-05 | 2006-04-20 | Ctp Hydrogen Corporation | Conducting ceramics for electrochemical systems |
| JP4699074B2 (en) * | 2005-04-15 | 2011-06-08 | 新日本製鐵株式会社 | Solid electrolyte membrane reactor |
| JP5057684B2 (en) * | 2006-03-31 | 2012-10-24 | 日本特殊陶業株式会社 | Hydrogen production equipment |
| JP2009057269A (en) * | 2007-08-08 | 2009-03-19 | Tdk Corp | Oxygen permeation module and system for generating hydrogen |
| JP4885159B2 (en) * | 2008-02-25 | 2012-02-29 | 株式会社ノリタケカンパニーリミテド | Oxygen separation membrane element |
| JP2012106238A (en) * | 2010-10-28 | 2012-06-07 | Mitsubishi Heavy Ind Ltd | Manufacturing method of oxygen permeation body |
| JP2020015636A (en) * | 2018-07-24 | 2020-01-30 | 株式会社デンソー | Fuel reformer |
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