JP4867084B2 - Hydrogen purification equipment - Google Patents
Hydrogen purification equipment Download PDFInfo
- Publication number
- JP4867084B2 JP4867084B2 JP2001176571A JP2001176571A JP4867084B2 JP 4867084 B2 JP4867084 B2 JP 4867084B2 JP 2001176571 A JP2001176571 A JP 2001176571A JP 2001176571 A JP2001176571 A JP 2001176571A JP 4867084 B2 JP4867084 B2 JP 4867084B2
- Authority
- JP
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- Prior art keywords
- hydrogen
- catalyst
- zeolite
- catalyst body
- carbon monoxide
- 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.)
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- 229910052739 hydrogen Inorganic materials 0.000 title claims description 51
- 239000001257 hydrogen Substances 0.000 title claims description 51
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 title claims description 49
- 238000000746 purification Methods 0.000 title claims description 14
- 239000003054 catalyst Substances 0.000 claims description 88
- 238000006243 chemical reaction Methods 0.000 claims description 55
- 239000007789 gas Substances 0.000 claims description 42
- 229910021536 Zeolite Inorganic materials 0.000 claims description 35
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 claims description 35
- 239000010457 zeolite Substances 0.000 claims description 35
- 229910000510 noble metal Inorganic materials 0.000 claims description 22
- 229910002091 carbon monoxide Inorganic materials 0.000 claims description 21
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 claims description 19
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 16
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims description 14
- 229910052802 copper Inorganic materials 0.000 claims description 12
- 229910052684 Cerium Inorganic materials 0.000 claims description 9
- 229910052697 platinum Inorganic materials 0.000 claims description 8
- 239000000377 silicon dioxide Substances 0.000 claims description 8
- 229910052804 chromium Inorganic materials 0.000 claims description 7
- 229910052742 iron Inorganic materials 0.000 claims description 7
- 229910018072 Al 2 O 3 Inorganic materials 0.000 claims description 6
- 229910004298 SiO 2 Inorganic materials 0.000 claims description 6
- 229910052750 molybdenum Inorganic materials 0.000 claims description 6
- 229910052702 rhenium Inorganic materials 0.000 claims description 6
- 229910052721 tungsten Inorganic materials 0.000 claims description 6
- 238000011144 upstream manufacturing Methods 0.000 claims description 6
- 229910052763 palladium Inorganic materials 0.000 claims description 5
- 229910052703 rhodium Inorganic materials 0.000 claims description 5
- 229910052707 ruthenium Inorganic materials 0.000 claims description 5
- 229910052723 transition metal Inorganic materials 0.000 claims description 4
- 150000002431 hydrogen Chemical class 0.000 claims description 3
- 229910052761 rare earth metal Inorganic materials 0.000 claims description 3
- 230000001590 oxidative effect Effects 0.000 claims description 2
- 229910052789 astatine Inorganic materials 0.000 claims 1
- 150000002500 ions Chemical group 0.000 claims 1
- 238000007670 refining Methods 0.000 claims 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 20
- 239000010949 copper Substances 0.000 description 15
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 14
- 230000000694 effects Effects 0.000 description 14
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 13
- 229910002092 carbon dioxide Inorganic materials 0.000 description 7
- 239000001569 carbon dioxide Substances 0.000 description 7
- 239000000446 fuel Substances 0.000 description 7
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Substances [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 7
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 6
- 239000011651 chromium Substances 0.000 description 6
- 230000000052 comparative effect Effects 0.000 description 6
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 5
- 229910052878 cordierite Inorganic materials 0.000 description 5
- 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 5
- 238000007254 oxidation reaction Methods 0.000 description 5
- 239000001301 oxygen Substances 0.000 description 5
- 229910052760 oxygen Inorganic materials 0.000 description 5
- 239000000203 mixture Substances 0.000 description 4
- 239000003345 natural gas Substances 0.000 description 4
- 239000011148 porous material Substances 0.000 description 4
- 238000002407 reforming Methods 0.000 description 4
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 230000008859 change Effects 0.000 description 3
- TVZPLCNGKSPOJA-UHFFFAOYSA-N copper zinc Chemical compound [Cu].[Zn] TVZPLCNGKSPOJA-UHFFFAOYSA-N 0.000 description 3
- 230000002209 hydrophobic effect Effects 0.000 description 3
- 238000006722 reduction reaction Methods 0.000 description 3
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 2
- GXDVEXJTVGRLNW-UHFFFAOYSA-N [Cr].[Cu] Chemical compound [Cr].[Cu] GXDVEXJTVGRLNW-UHFFFAOYSA-N 0.000 description 2
- 238000001994 activation Methods 0.000 description 2
- 125000004429 atom Chemical group 0.000 description 2
- 230000003197 catalytic effect Effects 0.000 description 2
- 229910000420 cerium oxide Inorganic materials 0.000 description 2
- 229910052681 coesite Inorganic materials 0.000 description 2
- 229910052593 corundum Inorganic materials 0.000 description 2
- 229910052906 cristobalite Inorganic materials 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 238000009792 diffusion process Methods 0.000 description 2
- 239000012013 faujasite Substances 0.000 description 2
- 238000004817 gas chromatography Methods 0.000 description 2
- 239000011810 insulating material Substances 0.000 description 2
- 230000007246 mechanism Effects 0.000 description 2
- 229910052680 mordenite Inorganic materials 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- BMMGVYCKOGBVEV-UHFFFAOYSA-N oxo(oxoceriooxy)cerium Chemical compound [Ce]=O.O=[Ce]=O BMMGVYCKOGBVEV-UHFFFAOYSA-N 0.000 description 2
- 239000010970 precious metal Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 235000012239 silicon dioxide Nutrition 0.000 description 2
- 238000001179 sorption measurement Methods 0.000 description 2
- 229910052682 stishovite Inorganic materials 0.000 description 2
- 150000003624 transition metals Chemical class 0.000 description 2
- 229910052905 tridymite Inorganic materials 0.000 description 2
- 229910001845 yogo sapphire Inorganic materials 0.000 description 2
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 1
- 230000004913 activation Effects 0.000 description 1
- 239000004480 active ingredient Substances 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- UPHIPHFJVNKLMR-UHFFFAOYSA-N chromium iron Chemical compound [Cr].[Fe] UPHIPHFJVNKLMR-UHFFFAOYSA-N 0.000 description 1
- 239000011248 coating agent Substances 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 239000003502 gasoline Substances 0.000 description 1
- 230000020169 heat generation Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 239000011261 inert gas Substances 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 239000002923 metal particle Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 238000006011 modification reaction Methods 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 231100000572 poisoning Toxicity 0.000 description 1
- 230000000607 poisoning effect Effects 0.000 description 1
- 239000005518 polymer electrolyte Substances 0.000 description 1
- 238000010248 power generation Methods 0.000 description 1
- 150000002910 rare earth metals Chemical class 0.000 description 1
- 239000012495 reaction gas Substances 0.000 description 1
- 238000006057 reforming reaction Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000000629 steam reforming Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- 210000002268 wool Anatomy 0.000 description 1
- 229910052727 yttrium Inorganic materials 0.000 description 1
Images
Classifications
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- 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
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
-
- 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
-
- 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
- Y02P20/584—Recycling of catalysts
Description
【０００１】
【発明の属する技術分野】
本発明は、水素を主成分とし一酸化炭素（以下ＣＯと記す）を含有する改質ガスを精製し、高純度の水素ガスを提供する水素精製装置に関する。
【０００２】
【従来の技術】
燃料電池などの水素源として、炭化水素もしくはアルコール、エーテルなどの改質によって得られる改質ガスを用いるが、１００℃以下の低温で動作する固体高分子型燃料電池の場合には、燃料電池の電極に用いるＰｔ触媒が改質ガスに含まれるＣＯによって被毒される恐れがある。Ｐｔ触媒の被毒が起こると、水素の反応が阻害され、燃料電池の発電効率が著しく低下する。そのため、水素精製装置を利用して、ＣＯを１００ｐｐｍ以下、好ましくは１０ｐｐｍ以下に除去する必要がある。
【０００３】
通常、ＣＯを除去するためには、水素精製装置における、ＣＯ変成触媒体を設置したＣＯ変成部でＣＯと水蒸気とをシフト反応させ、二酸化炭素と水素とに転換し、数千ｐｐｍ〜１％程度の濃度までＣＯ濃度を低減させる。
【０００４】
その後、微量の空気を利用して酸素を加え、ＣＯ選択酸化触媒体によって、燃料電池に悪影響をおよぼさない数ｐｐｍレベルまでＣＯを除去する。ここで、充分にＣＯを除去するためには、ＣＯ濃度の１〜３倍程度の酸素を加える必要があるが、このとき、水素も酸素量に対応して消費される。そして、ＣＯ濃度が高い場合には、加えるべき酸素量も増加し、消費される水素が増大するため、装置全体の効率が大きく低下する。
【０００５】
したがって、ＣＯ変成触媒体を設置したＣＯ変成部において、ＣＯを充分に低減させておくことが必要となる。
【０００６】
従来から、ＣＯ変成触媒には、低温用ＣＯ変成触媒として、１５０〜３００℃で使用可能な銅−亜鉛系触媒、銅−クロム系触媒などが用いられ、高温用ＣＯ変成触媒として、３００℃以上で機能する鉄−クロム系触媒などが用いられている。これらのＣＯ変成触媒は、化学プラントや燃料電池用水素発生器などの用途に応じて、低温用ＣＯ変成触媒のみで使用したり、高温用ＣＯ変成触媒と低温用ＣＯ変成触媒とを組み合わせて使用されていた。
【０００７】
【発明が解決しようとする課題】
しかしながら、上記の銅系の低温用ＣＯ変成触媒を中心に用いた場合、非常に高い触媒活性が得られるが、使用前に還元処理を施して活性化させる必要がある。そして、活性化処理中に発熱するため、触媒が耐熱温度以上にならないように、例えば還元ガスの供給量を調節しながら、長時間かけて処理する必要があった。また、一度活性化させたＣＯ変成触媒は、装置の停止時などに酸素が混入した場合には再酸化されて劣化する可能性があるため、酸化を防止するなどの対策が必要であった。さらに、低温用ＣＯ変成触媒は、耐熱性が低く、装置の始動時に触媒を急激に加熱することができないため、徐々に温度を上昇させるなどの対策が必要であった。
【０００８】
一方、高温用ＣＯ変成触媒のみを用いた場合には、耐熱性が高く温度が多少上昇しすぎても問題はないため、始動時の加熱などが容易になる。
【０００９】
しかしながら、ＣＯ変成反応は、高温領域においてＣＯ濃度を低減させる方向には進行しにくい平衡反応であり、高温でしか機能しない高温用ＣＯ変成触媒を用いた場合には、ＣＯ濃度を１％以下にすることが困難であった。そのため、後に接続するＣＯ浄化部での浄化効率が低下してしまうことがあった。
【００１０】
このように、従来の技術においては、たとえば、水素精製装置の起動に時間を要したり、取り扱いが煩雑なため、頻繁に起動停止を繰り返す用途には、充分には適用できないという課題があった。
【００１１】
本発明は、上記従来のこのような課題を考慮し、たとえば、始動時の加熱などが容易であり、高いＣＯ浄化効率を有する水素精製装置を提供することを目的とする。
【００１２】
【課題を解決するための手段】
第一の本発明（請求項１に対応）は、水素、一酸化炭素および水蒸気を含む改質ガスから一酸化炭素を除去する一酸化炭素変成触媒体を備えた水素精製装置であって、前記一酸化炭素変成触媒体は、ゼオライトにＣｕ、Ｆｅ、Ｃｒ、Ｃｅ、Ｒｅ、Ｍｏ、Ｗから選択される希土類元素または遷移金属元素のうちの少なくとも一種と、Ｐｔ、Ｐｄ、Ｒｈ、Ｒｕのうちの少なくとも１つの貴金属がイオン交換または担持されており、前記ゼオライトはシリカおよびアルミナを主成分とし、ＳｉＯ 2 ／Ａｌ 2 Ｏ 3 比が４以上であることを特徴とする水素精製装置である。
【００１３】
第二の本発明（請求項２に対応）は、前記一酸化炭素変成触媒体は、前記ゼオライトに少なくともＣｅとＰｔがイオン交換または担持されていることを特徴とする水素精製装置である。
【００１６】
第三の本発明（請求項３に対応）は、前記ゼオライトは、Ｙ型、Ｌ型、モルデナイト型、ＺＳＭ−５型、ベータ型構造より選択される一種であることを特徴とする水素精製装置である。
【００１７】
第四の本発明（請求項４に対応）は、前記一酸化炭素変成触媒体の上流側には酸化ガス供給部が設けられていることを特徴とする水素精製装置である。
【００１８】
第五の本発明（請求項５に対応）は、前記ゼオライトには少なくともＣｕが含有していることを特徴とする水素精製装置である。
【００１９】
【発明の実施の形態】
以下では、本発明にかかる実施の形態について、図面を参照しつつ説明を行う。
【００２０】
（実施の形態１）
はじめに、図１を参照しながら、本実施の形態における水素精製装置の構成について説明する。なお、図１は、本実施の形態における水素精製装置の構成を示す概略縦断面図である。
【００２１】
図１において、１はＣＯ変成触媒体（以下では、単に触媒体ともいう）であり、反応室２の内部に設置した。３は改質ガス入口であり、ここから改質ガスを導入する。触媒体１で反応した改質ガスは、改質ガス出口より排出される。
【００２２】
なお、触媒体１の上流側には、改質ガスが均一に流れるように拡散板５を設置してある。また、反応器を一定温度に保つために、必要箇所は、外周をセラミックウールからなる断熱材６で覆ってある。
【００２３】
ここで、触媒体１は、ＳｉＯ２／Ａｌ２Ｏ３＝５（モル比）のＹ型ゼオライト（フォージャサイト型でシリカ−アルミナ比が４以上のもの）にＣｅとＰｔを担持したものをコージェライトハニカムにコーティングすることによって作成した。
【００２４】
つぎに、本実施の形態における水素精製装置の動作について説明する。水素精製装置に供給する改質ガスを発生させるために用いる燃料としては、天然ガス、メタノール、ガソリンなどがあり、改質方法も、水蒸気を加える水蒸気改質、空気を加えておこなう部分改質などがあるが、ここでは、天然ガスを水蒸気改質して改質ガスを得る場合について述べる。
【００２５】
天然ガスを水蒸気改質した場合の改質ガスの組成は、改質触媒体の温度によって多少変化するが、水蒸気を除いた平均的な値として、水素が約８０％、二酸化炭素、一酸化炭素がそれぞれ約１０％含まれる。
【００２６】
天然ガスの改質反応は、５００〜８００℃程度でおこなうのに対し、ＣＯと水蒸気が反応する変成反応は、１５０〜３５０℃程度で進行するため、改質ガスは、改質ガス入口３の手前で冷却してから供給する。触媒体１通過後のＣＯ濃度は、約１％まで低減され、改質ガス出口４より排出される。
【００２７】
次に、本実施の形態の水素精製装置の動作原理について説明する。ＣＯ変成反応は、温度に依存する平衡反応であり、低温で反応させるほど、ＣＯ濃度を低減させることができる。一方、低温になると触媒上での反応速度が低下する。したがって、ＣＯ濃度が極小値をとる温度が存在する。
【００２８】
従来の水素精製装置においてＣＯ変成触媒として用いられる銅−亜鉛触媒、銅−クロム触媒などの銅系の変成触媒は、１５０〜２５０℃の低温でＣＯ変成反応を行うことができ、条件によっては、ＣＯ濃度を数百〜千ｐｐｍ前後にまで低減させることができる。
【００２９】
しかし、銅系の触媒は、反応器に充填した後、水素や改質ガスなどの還元ガスを流通させて活性化させる必要があるとともに、耐熱性は３００℃前後と低い。したがって、活性化時の反応熱で耐熱温度を超えないように、還元ガスを不活性ガスなどで希釈して供給するか、または少流量で徐々に反応させる必要があり、活性化に長時間を要する。また、装置の起動時にも、過昇温によって耐熱温度を超えないように、ゆっくりと長時間かけて加熱する必要があり、頻繁に起動停止を繰り返すような用途には、問題点が多い。
【００３０】
一方、本発明の水素精製装置では、触媒体１として貴金属を活性成分とする触媒体を用いており、装置の起動時に５００℃程度の高温になった場合でも、触媒が大きく劣化することは無い。また、触媒体１の耐熱性が高いため、銅系触媒のように、還元反応の反応熱による発熱を抑制するために、長時間かけて還元処理を行う必要もない。また、装置を停止させた場合に空気が混入しても銅系触媒よりも触媒劣化は少ない。
【００３１】
また、ゼオライトを担体として用いることによって、活性成分が高分散に担持されるとともに、担体であるゼオライトと貴金属との相互作用が大きいため劣化も抑制される。
【００３２】
ゼオライトはシリカとアルミナを主成分とするものが一般的であるが、３価の電子状態をとるＡｌ原子と４価の電子状態をとるＳｉ原子の比率によって、固体酸性や疎水性など様々な特性が発現する。本実施の形態で用いているゼオライトは、ＳｉＯ２／Ａｌ２Ｏ３比＝５であり、水に対して親和性の低い疎水性ゼオライトである。水素精製装置の起動時には、装置が充分な温度に昇温される前に水蒸気を多く含むガスが供給される可能性がある。このため、従来は触媒体に凝縮した水が触媒の活性点を覆い尽くし、反応が開始するまでに長い時間を要していたり、触媒をヒーターで加熱したりしていた。一方、本発明では疎水性ゼオライトを用いているため、水が触媒活性を低下させることなく、比較的低温から、速やかに反応がを開始させることができる。
【００３３】
なお、Ｐｔ、Ｐｄ、Ｒｈ、およびＲｕなどを活性成分とする貴金属触媒は、活性が高いために、反応の選択性が比較的低い。そのため、条件によっては、ＣＯ変成反応の副反応として、ＣＯまたは二酸化炭素のメタン化反応も進行することがあり、メタン化反応の進行による水素の消費が、装置全体の効率を低下させることが懸念される。
【００３４】
通常、ＣＯ変成反応を行う１５０〜４５０℃の温度領域では、高温になるほどメタン化反応が顕著となるが、貴金属の種類によっても、メタン生成率は異なる。これは、貴金属の種類によってＣＯの吸着機構が異なるためであり、メタン化反応が進行しやすいＣＯの吸着機構をもつＰｄ、ＲｈおよびＲｕは、比較的低温でもメタンを発生させ、ＣＯ変成反応を行うことができる温度領域が狭くなる。これに対して、本実施の形態で用いるＰｔ触媒は、メタン化反応を起こしにくく、広い温度範囲でＣＯ変成反応を行うことができる。したがって、メタン化反応の進行によって大量の水素が消費されることはなく、本実施の形態の水素精製装置は、効率よく稼働することができる。
【００３５】
また、貴金属の担持量としては、貴金属が高い分散度となり、必要な活性が発揮できる量であれば良い。貴金属の含有量が高いほど貴金属の粒子は大きくなって反応に寄与しない貴金属量が増加し、逆に貴金属の含有量が少ない場合には充分な活性が得られない。このため、通常の燃焼用や排ガス浄化用の貴金属触媒と同じく、触媒担体に対して０．１重量％〜５重量％の間が好ましい。
【００３６】
また、Ｃｅは貴金属触媒上でのメタン化反応を抑制する効果がある。通常貴金属触媒にはアルミナやシリカ、酸化チタン等が触媒担体として用いられるが、変成反応に用いると３００℃以上の温度領域で、メタン化反応が進行しやすい。Ｃｅを貴金属と共存させた場合には、４５０℃程度の高温であっても、メタン化反応はほとんど進行しない。Ｃｅ以外にもＣｕ、Ｆｅ、Ｃｒ、Ｒｅ、Ｍｏ、Ｗから選択される遷移金属を添加することによって、同様の効果が得られる。
【００３７】
Ｃｕ、Ｆｅ、Ｃｒ、Ｃｅ、Ｒｅ、Ｍｏ、Ｗの添加量としては、ゼオライトの細孔内に
効率よく担持できる量が好ましく、０．５〜１０ｗｔ％がもっとも効果的である。
【００３８】
また、本実施例ではＹ型構造のゼオライトを用いたが、反応ガス（ＣＯと水分子）に対して充分に大きな細孔を有していれば、特に構造に限定はなく、Ｌ型、モルデナイト型、ＺＳＭ−５型、ベータ型構造でもよい。これらのものは０．５〜１ｎｍの細孔を有しており、細孔内の活性点が有効に機能できるため、高い活性が得られる。
【００３９】
また本実施の形態では、ゼオライトのシリカ−アルミナ比がＳｉＯ2／Ａｌ2Ｏ3＝５のものを用いたが、４以上であれば、高い性能が得られる。また、シリカ比率が多いほど疎水性が高くなって好ましいが、ＳｉＯ2／Ａｌ2Ｏ3＝２００を越えると、シリカの比率が多くなっても特性は変わらない。
【００４０】
また、本実施の形態では、触媒体の形状は、触媒をコージェライトハニカムにコーティングしたものを用いたが、ゼオライトの形状をペレット形状とし、貴金属塩等を含浸させてＣＯ変成触媒体を作製しても、同様の性能を有するＣＯ変成触媒体が得られる。
【００４１】
また、本実施の形態では、ゼオライトにＣｅとＰｔを担持したが、酸化セリウム等の金属酸化物に貴金属を担持したものとゼオライトを混合しても同様の効果が得られる。
【００４２】
（実施の形態２）
次に発明の第２の実施の形態について述べる。本実施の形態は、図２に示すように触媒体１１の上流側に空気供給部１４が設けている以外は実施の形態１と類似である。したがって、異なる点を中心に本実施の形態を説明する。
【００４３】
図２は本実施の形態に係る水素精製装置の構成を示す概略断面図である。空気供給部１４から空気を供給することによって、触媒体１１で改質ガス中の水素または一酸化炭素が酸化される。通常、起動時には触媒体１１の温度が充分に上昇するまで触媒上に水が凝縮し、酸化反応は充分に進行しない。このため、空気を加えても発熱しないため、起動に時間を要する。ここで本実施の形態では触媒体１１には疎水性ゼオライトが含有しており、装置の起動時のように、多量の水蒸気が含まれている条件でも触媒体１１上で酸化反応が進行し、触媒体１１の温度は速やかに上昇する。なお、加える空気量は装置構成等によって異なり、特に限定しないが、触媒温度が速やかに昇温するとともに、極端に触媒体の温度が過昇温しない空気量を選択する必要がある。
【００４４】
また、触媒体１１に用いているゼオライトにＣｕを担持させておくと、触媒の酸化反応が開始する温度より低温で、供給した空気がＣｕを酸化し発熱するため、触媒体１１の温度はより早く上昇する。一度酸化された銅は空気の供給を停止すると再び改質ガスによって還元されるため、元の金属状態にもどり、次の起動時には再び発熱させることができる。
【００４５】
【実施例】
（実施例１）
表１に示すように、シリカ−アルミナ比がＳｉＯ2／Ａｌ2Ｏ3＝５のＹ型ゼオライト（表中ではＹと記す）に対して、Ｃｕ、Ｆｅ、Ｃｒ、Ｃｅ、Ｒｅ、Ｍｏ、Ｗを１重量％担持し、さらに貴金属（貴金属種は表中に記載）を１重量％担持した。同じくシリカ−アルミナ比がＳｉＯ2／Ａｌ2Ｏ3＝５のＬ型、モルデナイト型、ＺＳＭ５型、ベータ型ゼオライト（表中では、それぞれＬ、Ｍ、ＺＳＭ５、βと記す）に対して、Ｃｅを１重量％担持し、同様にＰｔを１重量％担持した。これらをコージェライトハニカムにコーティングして、図１に示す反応室２に設置した。
【００４６】
改質ガス入口３より、一酸化炭素８％、二酸化炭素８％、水蒸気２０％、残りが水素である改質ガスを、毎分１０リットルの流量で導入した。改質ガス温度を制御し、触媒体１で反応させた後に、改質ガス出口４より排出されるガスの組成をガスクロマトグラフィで測定した。
【００４７】
温度を変化させた場合のＣＯ濃度の最低値、触媒温度が４００℃における反応後のガス中のメタン濃度を測定し、さらに、装置を停止させた後、再び起動させる動作を１０回繰り返し、ＣＯ濃度の最低値を測定して触媒の活性変化を確認した。これらの結果を、表１にまとめて示す。
【００４８】
【表１】
表１に示された実験結果より、前述したつぎのような事実が裏付けられる。Ｃｕ、Ｆｅ、Ｃｒ、Ｃｅ、Ｒｅ、Ｍｏ、ＷとＰｔを担持したＹ型ゼオライトは活性が高く、メタン化反応も抑制できる。特にＣｅがもっとも効果的である。また、Ｐｔの代わりにＲｕ、Ｐｄ、およびＲｈを用いた場合には、メタン化反応が起こりやすくなり、メタン濃度が高くなる。
【００５０】
また、Ｌ型、モルデナイト型、ＺＳＭ５型、β型のゼオライトを用いてもＹ型ゼオライトと同様の効果が得られる。
【００５１】
（実施例２）
実施例１で用いた表１中の試料４に示したＰｔ／Ｃｅ／Ｙ型（フォージャサイト型）ゼオライトにおいて、表２に示すように、ゼオライトのシリカ−アルミナ比が、１から１０００までのものについて、実施例１と同様にコージェライトハニカムにコーティングして、図１に示す反応室２に設置した。
【００５２】
改質ガス入口３より、一酸化炭素８％、二酸化炭素８％、水蒸気２０％、残りが水素である改質ガスを、毎分１０リットルの流量で導入を開始し、触媒体１の温度が上昇してＣＯ濃度が１％を下回るまでの時間（起動時間）を測定した。これらの結果を表２にまとめて示す。
【００５３】
【表２】
（実施例３）
実施例２で、図２に示すように触媒体１１の上流側に空気供給部１４を設け、毎分０．２リットルの流量で空気を供給しながら、実施例２と同様に起動時間を測定した。これらの結果を表３にまとめて示す。
【００５５】
【表３】
（実施例４）
実施例１で用いた表１中の試料１で示したＰｔ／Ｃｕ／Ｙ型ゼオライトにおいて、表４に示すように、ゼオライトのシリカ−アルミナ比が、１から１０００までのものについて、実施例３と同様に起動時間を測定した。これらの結果を表４にまとめて示す。
【００５７】
【表４】
（比較例１）
本発明のゼオライトに希土類または遷移金属を担持させたものの代わりに、表５に示す組成の酸化物、または貴金属１重量％をアルミナに担持したもの、４２〜４７を触媒体１として用い、実施例１と同様に、図１に示す反応室２に設置した。改質ガス入口３より、一酸化炭素８％、二酸化炭素８％、水蒸気２０％、残りが水素である改質ガスを、毎分１０リットルの流量で導入した。改質ガス温度を制御し、触媒体１で反応させた後に、改質ガス出口４より排出されるガスの組成をガスクロマトグラフィで測定した。温度を変化させた場合のＣＯ濃度の最低値、触媒温度が４００℃における反応後のガス中のメタン濃度を測定し、さらに、装置を停止させた後、再び起動させる動作を１０回繰り返し、ＣＯ濃度の最低値を測定して触媒の活性変化を確認した。これらの結果を、表５にまとめて示す。
【００５９】
【表５】
（比較例２）
実施例１で用いた表１中の試料４に示したＰｔ／Ｃｅ／Ｙ型ゼオライト代わりに、酸化セリウムにＰｔを１重量％担持し、実施例１と同様にコージェライトハニカムにコーティングして、図１に示す反応室２に設置した。
【００６１】
改質ガス入口３より、一酸化炭素８％、二酸化炭素８％、水蒸気２０％、残りが水素である改質ガスを、毎分１０リットルの流量で導入を開始し、触媒体１の温度が上昇してＣＯ濃度が１％を下回るまでの時間（起動時間）を測定したところ、５５分であった。
【００６２】
（比較例３）
比較例２で、図２に示すように触媒体１１の上流側に空気供給部１４を設け、毎分０．２リットルの流量で空気を供給しながら、比較例２と同様に起動時間を測定したところ、４０分であった。
【００６３】
このように、本比較例における触媒体を用いた場合、次のような事実が裏付けられる。貴金属を含まない鉄とクロムの複合酸化物は充分にＣＯが低減できず、銅−亜鉛触媒は初期活性は高いが、起動停止を繰り返すと著しく活性低下する。また、アルミナに貴金属を担持させたものは、活性の低下はみられないが、４００℃におけるメタン濃度は高い。また、起動時間もゼオライトを用いることによって短くなった。
【００６４】
以上述べたところから明らかなように、このように、本発明の水素精製装置は、ＣＯ変成触媒体の耐久性が改善されており、装置の起動停止を繰り返した場合でも安定に動作し、起動時間も短縮することができる。
【００６５】
【発明の効果】
以上の説明から明らかなように、本発明は、たとえば、始動時の加熱などが容易であり、高いＣＯ除去効率を有する水素精製装置を提供することができる。
【図面の簡単な説明】
【図１】本発明の実施の形態１に係る水素精製装置を含む水素発生装置の構成を示す概略縦断面図
【図２】本発明の実施の形態２に係る水素精製装置を含む水素発生装置の構成を示す概略縦断面図
【符号の説明】
１，１１ 触媒体
２，１２ 反応室
３，１３ 改質ガス入口
４，１４ 改質ガス出口
５，１６ 拡散板
６，１７ 断熱材
１５ 空気供給部[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hydrogen purifier that purifies a reformed gas containing hydrogen as a main component and containing carbon monoxide (hereinafter referred to as CO) to provide high-purity hydrogen gas.
[0002]
[Prior art]
As a hydrogen source for a fuel cell or the like, a reformed gas obtained by reforming hydrocarbon, alcohol, ether or the like is used. In the case of a polymer electrolyte fuel cell operating at a low temperature of 100 ° C. or lower, the fuel cell The Pt catalyst used for the electrode may be poisoned by CO contained in the reformed gas. When poisoning of the Pt catalyst occurs, the reaction of hydrogen is inhibited, and the power generation efficiency of the fuel cell is significantly reduced. Therefore, it is necessary to remove CO to 100 ppm or less, preferably 10 ppm or less using a hydrogen purifier.
[0003]
Usually, in order to remove CO, CO and water vapor are shift-reacted in a CO conversion section where a CO conversion catalyst body is installed in a hydrogen purifier to convert it into carbon dioxide and hydrogen, and several thousand ppm to 1%. Reduce the CO concentration to a moderate concentration.
[0004]
Thereafter, oxygen is added using a small amount of air, and CO is removed to a few ppm level by the CO selective oxidation catalyst body that does not adversely affect the fuel cell. Here, in order to sufficiently remove CO, it is necessary to add oxygen of about 1 to 3 times the CO concentration. At this time, hydrogen is also consumed corresponding to the amount of oxygen. When the CO concentration is high, the amount of oxygen to be added also increases and the amount of hydrogen consumed increases, greatly reducing the efficiency of the entire apparatus.
[0005]
Therefore, it is necessary to sufficiently reduce CO in the CO shift section where the CO shift catalyst body is installed.
[0006]
Conventionally, as a CO conversion catalyst, a copper-zinc based catalyst, a copper-chromium based catalyst, etc. usable at 150 to 300 ° C. are used as a low temperature CO conversion catalyst, and as a high temperature CO conversion catalyst, 300 ° C. or more. An iron-chromium-based catalyst that functions in the above is used. These CO conversion catalysts can be used only for low temperature CO conversion catalysts or in combination with high temperature CO conversion catalysts and low temperature CO conversion catalysts, depending on the application such as chemical plant and fuel cell hydrogen generator. It had been.
[0007]
[Problems to be solved by the invention]
However, when the above-described copper-based low-temperature CO conversion catalyst is mainly used, a very high catalytic activity can be obtained, but it is necessary to activate it by performing a reduction treatment before use. Then, since heat is generated during the activation process, it is necessary to perform the treatment over a long time while adjusting the supply amount of the reducing gas, for example, so that the catalyst does not exceed the heat-resistant temperature. In addition, since the CO conversion catalyst once activated may be reoxidized and deteriorated when oxygen is mixed when the apparatus is stopped, it is necessary to take measures such as preventing oxidation. Furthermore, since the low temperature CO conversion catalyst has low heat resistance and cannot heat the catalyst rapidly at the start of the apparatus, it is necessary to take measures such as gradually increasing the temperature.
[0008]
On the other hand, when only the high-temperature CO conversion catalyst is used, there is no problem even if the temperature rises slightly because of high heat resistance, and heating at the time of start-up becomes easy.
[0009]
However, the CO shift reaction is an equilibrium reaction that does not easily proceed in the direction of reducing the CO concentration in the high temperature region. When a high temperature CO shift catalyst that functions only at high temperatures is used, the CO concentration is reduced to 1% or less. It was difficult to do. Therefore, the purification efficiency in the CO purification part connected later may fall.
[0010]
As described above, in the conventional technology, for example, it takes time to start up the hydrogen purifier or the handling is complicated, and thus there is a problem that it cannot be sufficiently applied to a use that repeatedly starts and stops. .
[0011]
An object of the present invention is to provide a hydrogen purifier having high CO purification efficiency that can be easily heated at the start, for example, in consideration of the above-described conventional problems.
[0012]
[Means for Solving the Problems]
A first aspect of the present invention (corresponding to claim 1) is a hydrogen purification apparatus comprising a carbon monoxide shift catalyst body for removing carbon monoxide from a reformed gas containing hydrogen, carbon monoxide and steam, The carbon monoxide shift catalyst body is made of at least one of rare earth elements or transition metal elements selected from Cu, Fe, Cr, Ce, Re, Mo, and W, and Pt, Pd, Rh, and Ru. The hydrogen purifier is characterized in that at least one noble metal is ion-exchanged or supported , the zeolite is mainly composed of silica and alumina, and the SiO 2 / Al 2 O 3 ratio is 4 or more .
[0013]
A second aspect of the present invention (corresponding to claim 2) is the hydrogen purifier characterized in that the carbon monoxide shift catalyst body has at least Ce and Pt ion-exchanged or supported on the zeolite.
[0016]
According to a third aspect of the present invention (corresponding to claim 3 ), the zeolite is a kind selected from a Y type, an L type, a mordenite type, a ZSM-5 type, and a beta type structure. It is.
[0017]
A fourth aspect of the present invention (corresponding to claim 4 ) is a hydrogen purification apparatus characterized in that an oxidizing gas supply unit is provided upstream of the carbon monoxide shift catalyst body.
[0018]
A fifth aspect of the present invention (corresponding to claim 5 ) is a hydrogen purifier characterized in that the zeolite contains at least Cu.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments according to the present invention will be described with reference to the drawings.
[0020]
(Embodiment 1)
First, the configuration of the hydrogen purification apparatus in the present embodiment will be described with reference to FIG. In addition, FIG. 1 is a schematic longitudinal cross-sectional view which shows the structure of the hydrogen purification apparatus in this Embodiment.
[0021]
In FIG. 1, reference numeral 1 denotes a CO conversion catalyst body (hereinafter also simply referred to as a catalyst body), which is installed inside the reaction chamber 2. Reference numeral 3 denotes a reformed gas inlet from which the reformed gas is introduced. The reformed gas reacted at the catalyst body 1 is discharged from the reformed gas outlet.
[0022]
A diffusion plate 5 is installed on the upstream side of the catalyst body 1 so that the reformed gas flows uniformly. Further, in order to keep the reactor at a constant temperature, the necessary portion is covered with a heat insulating material 6 made of ceramic wool at the outer periphery.
[0023]
Here, the catalyst body 1 is a cordierite honeycomb in which Ce and Pt are supported on a Y-type zeolite (a faujasite type having a silica-alumina ratio of 4 or more) of SiO2 / Al2O3 = 5 (molar ratio). Created by coating.
[0024]
Next, the operation of the hydrogen purifier in the present embodiment will be described. Fuels used to generate reformed gas to be supplied to the hydrogen purifier include natural gas, methanol, gasoline, etc., and reforming methods include steam reforming with steam, partial reforming with air, etc. Here, a case where natural gas is steam reformed to obtain a reformed gas will be described.
[0025]
The composition of the reformed gas when the natural gas is steam reformed varies slightly depending on the temperature of the reforming catalyst body, but as an average value excluding steam, hydrogen is about 80%, carbon dioxide, carbon monoxide. About 10% of each.
[0026]
The reforming reaction of natural gas is performed at about 500 to 800 ° C., whereas the modification reaction in which CO and water vapor are reacted proceeds at about 150 to 350 ° C. Supply after cooling in front. The CO concentration after passing through the catalyst body 1 is reduced to about 1% and discharged from the reformed gas outlet 4.
[0027]
Next, the principle of operation of the hydrogen purification apparatus of this embodiment will be described. The CO shift reaction is an equilibrium reaction depending on temperature, and the CO concentration can be reduced as the reaction is performed at a lower temperature. On the other hand, when the temperature is low, the reaction rate on the catalyst decreases. Therefore, there is a temperature at which the CO concentration takes a minimum value.
[0028]
Copper-based shift catalysts such as copper-zinc catalyst and copper-chromium catalyst used as CO shift catalysts in conventional hydrogen purifiers can perform CO shift reaction at a low temperature of 150 to 250 ° C., depending on conditions, The CO concentration can be reduced to around several hundred to 1,000 ppm.
[0029]
However, the copper-based catalyst needs to be activated by flowing a reducing gas such as hydrogen or reformed gas after filling the reactor, and the heat resistance is low at around 300 ° C. Therefore, it is necessary to dilute and supply the reducing gas with an inert gas or the like so as not to exceed the heat resistance temperature due to the reaction heat at the time of activation. Cost. Also, at the time of starting the apparatus, it is necessary to heat slowly over a long time so as not to exceed the heat-resistant temperature due to excessive temperature rise, and there are many problems in applications where frequent start and stop are repeated.
[0030]
On the other hand, in the hydrogen purification apparatus of the present invention, a catalyst body having a noble metal as an active component is used as the catalyst body 1, and the catalyst is not greatly deteriorated even when the temperature becomes about 500 ° C. when the apparatus is started. . Moreover, since the heat resistance of the catalyst body 1 is high, it is not necessary to perform the reduction treatment over a long time in order to suppress the heat generation due to the reaction heat of the reduction reaction unlike the copper catalyst. Further, even when air is mixed when the apparatus is stopped, the catalyst is less deteriorated than the copper catalyst.
[0031]
Further, by using zeolite as a support, the active ingredient is supported in a highly dispersed manner, and deterioration is also suppressed because of the large interaction between the support zeolite and the noble metal.
[0032]
Zeolite is generally composed mainly of silica and alumina, but various properties such as solid acidity and hydrophobicity depend on the ratio of Al atoms that take a trivalent electronic state and Si atoms that take a tetravalent electronic state. Is expressed. The zeolite used in the present embodiment is a hydrophobic zeolite having a SiO2 / Al2O3 ratio = 5 and low affinity for water. When the hydrogen purification apparatus is started, there is a possibility that a gas containing a large amount of water vapor is supplied before the apparatus is heated to a sufficient temperature. For this reason, conventionally, water condensed in the catalyst body covers the active point of the catalyst, and it takes a long time to start the reaction or the catalyst is heated with a heater. On the other hand, since hydrophobic zeolite is used in the present invention, the reaction can be started promptly from a relatively low temperature without reducing the catalytic activity of water.
[0033]
Note that a noble metal catalyst containing Pt, Pd, Rh, Ru, or the like as an active component has a high activity and therefore has a relatively low reaction selectivity. Therefore, depending on conditions, the methanation reaction of CO or carbon dioxide may also proceed as a side reaction of the CO shift reaction, and there is a concern that the consumption of hydrogen due to the progress of the methanation reaction may reduce the efficiency of the entire apparatus. Is done.
[0034]
Usually, in the temperature range of 150 to 450 ° C. in which the CO shift reaction is performed, the methanation reaction becomes more prominent as the temperature increases, but the methane production rate varies depending on the type of noble metal. This is because the CO adsorption mechanism varies depending on the type of precious metal. Pd, Rh and Ru, which have a CO adsorption mechanism that facilitates the methanation reaction, generate methane even at relatively low temperatures, and perform the CO conversion reaction. The temperature range that can be performed is narrowed. On the other hand, the Pt catalyst used in the present embodiment hardly causes methanation reaction and can perform CO shift reaction in a wide temperature range. Therefore, a large amount of hydrogen is not consumed by the progress of the methanation reaction, and the hydrogen purification apparatus of this embodiment can be operated efficiently.
[0035]
In addition, the amount of the noble metal supported may be an amount that allows the noble metal to have a high degree of dispersion and exhibit the necessary activity. As the noble metal content increases, the noble metal particles become larger and the amount of noble metal that does not contribute to the reaction increases. Conversely, when the noble metal content is low, sufficient activity cannot be obtained. For this reason, it is preferably between 0.1% by weight and 5% by weight with respect to the catalyst carrier as in the case of a normal noble metal catalyst for combustion or exhaust gas purification.
[0036]
Ce has an effect of suppressing the methanation reaction on the noble metal catalyst. Usually, alumina, silica, titanium oxide or the like is used as a catalyst carrier for the noble metal catalyst. However, when used for the shift reaction, the methanation reaction is likely to proceed in a temperature range of 300 ° C. or higher. When Ce coexists with a noble metal, the methanation reaction hardly proceeds even at a high temperature of about 450 ° C. The same effect can be obtained by adding a transition metal selected from Cu, Fe, Cr, Re, Mo, and W in addition to Ce.
[0037]
The addition amount of Cu, Fe, Cr, Ce, Re, Mo, and W is preferably an amount that can be efficiently supported in the pores of the zeolite, and 0.5 to 10 wt% is most effective.
[0038]
In this example, zeolite with a Y-type structure was used. However, the structure is not particularly limited as long as it has sufficiently large pores for the reaction gas (CO and water molecules), and L-type, mordenite. A type, ZSM-5 type, or beta type structure may be used. Since these have pores of 0.5 to 1 nm and active points in the pores can function effectively, high activity can be obtained.
[0039]
Further, in this embodiment, the zeolite having a silica-alumina ratio of SiO 2 / Al 2 O 3 = 5 is used, but if it is 4 or more, high performance can be obtained. Further, the higher the silica ratio, the higher the hydrophobicity and the better. However, when SiO 2 / Al 2 O 3 = 200 is exceeded, the characteristics do not change even if the silica ratio increases.
[0040]
In the present embodiment, the catalyst body used is a cordierite honeycomb coated with a catalyst. However, the zeolite is formed into a pellet shape and impregnated with a noble metal salt or the like to produce a CO conversion catalyst body. However, a CO conversion catalyst body having similar performance can be obtained.
[0041]
In the present embodiment, Ce and Pt are supported on zeolite. However, the same effect can be obtained by mixing zeolite and a metal oxide such as cerium oxide supported with noble metal.
[0042]
(Embodiment 2)
Next, a second embodiment of the invention will be described. This embodiment is similar to the first embodiment except that an air supply unit 14 is provided on the upstream side of the catalyst body 11 as shown in FIG. Therefore, this embodiment will be described focusing on the different points.
[0043]
FIG. 2 is a schematic cross-sectional view showing the configuration of the hydrogen purifier according to the present embodiment. By supplying air from the air supply unit 14, hydrogen or carbon monoxide in the reformed gas is oxidized by the catalyst body 11. Usually, at the time of start-up, water is condensed on the catalyst until the temperature of the catalyst body 11 is sufficiently increased, and the oxidation reaction does not proceed sufficiently. For this reason, since it does not generate heat even if air is added, it takes time to start. Here, in the present embodiment, the catalyst body 11 contains hydrophobic zeolite, and the oxidation reaction proceeds on the catalyst body 11 even under a condition in which a large amount of water vapor is contained as in the start-up of the apparatus. The temperature of the catalyst body 11 rises quickly. The amount of air to be added varies depending on the apparatus configuration and the like, and is not particularly limited. However, it is necessary to select an amount of air in which the catalyst temperature is rapidly raised and the temperature of the catalyst body is not excessively raised.
[0044]
In addition, if Cu is supported on the zeolite used for the catalyst body 11, the supplied air oxidizes Cu and generates heat at a temperature lower than the temperature at which the oxidation reaction of the catalyst starts. Ascend quickly. The copper once oxidized is reduced again by the reformed gas when the supply of air is stopped, so that it returns to the original metal state and can be reheated at the next start-up.
[0045]
【Example】
Example 1
As shown in Table 1, Cu, Fe, Cr, Ce, Re, Mo, W, and Y type zeolite (indicated in the table as Y) having a silica-alumina ratio of SiO 2 / Al 2 O 3 = 5 And 1% by weight of noble metal (noble metal species are listed in the table). Similarly, for L-type, mordenite-type, ZSM5-type, and beta-type zeolite (in the table, L, M, ZSM5, and β, respectively) having a silica-alumina ratio of SiO 2 / Al 2 O 3 = 5, Ce is used. 1% by weight was supported, and similarly 1% by weight of Pt was supported. These were coated on a cordierite honeycomb and installed in the reaction chamber 2 shown in FIG.
[0046]
From the reformed gas inlet 3, reformed gas having 8% carbon monoxide, 8% carbon dioxide, 20% water vapor and the remaining hydrogen was introduced at a flow rate of 10 liters per minute. After controlling the reformed gas temperature and reacting with the catalyst body 1, the composition of the gas discharged from the reformed gas outlet 4 was measured by gas chromatography.
[0047]
The minimum value of CO concentration when the temperature is changed and the methane concentration in the gas after the reaction at a catalyst temperature of 400 ° C. are measured, and the operation of starting the apparatus again after stopping the apparatus is repeated 10 times. The minimum value of the concentration was measured to confirm the change in the activity of the catalyst. These results are summarized in Table 1.
[0048]
[Table 1]
The following facts described above are supported by the experimental results shown in Table 1. Y-type zeolite supporting Cu, Fe, Cr, Ce, Re, Mo, W and Pt has high activity and can suppress the methanation reaction. In particular, Ce is the most effective. Further, when Ru, Pd, and Rh are used instead of Pt, the methanation reaction is likely to occur and the methane concentration is increased.
[0050]
Moreover, the same effect as that of Y-type zeolite can be obtained by using L-type, mordenite-type, ZSM5-type, and β-type zeolite.
[0051]
(Example 2)
In the Pt / Ce / Y type (faujasite type) zeolite shown in Sample 4 in Table 1 used in Example 1, as shown in Table 2, the silica-alumina ratio of the zeolite was from 1 to 1000. In the same manner as in Example 1, the cordierite honeycomb was coated and placed in the reaction chamber 2 shown in FIG.
[0052]
From the reformed gas inlet 3, introduction of reformed gas with 8% carbon monoxide, 8% carbon dioxide, 20% water vapor, and the remainder hydrogen is started at a flow rate of 10 liters per minute. The time (start-up time) until the CO concentration increased below 1% was measured. These results are summarized in Table 2.
[0053]
[Table 2]
(Example 3)
In Example 2, as shown in FIG. 2, an air supply unit 14 is provided on the upstream side of the catalyst body 11, and the startup time is measured in the same manner as in Example 2 while supplying air at a flow rate of 0.2 liters per minute. did. These results are summarized in Table 3.
[0055]
[Table 3]
Example 4
In the Pt / Cu / Y type zeolite shown in Sample 1 in Table 1 used in Example 1, as shown in Table 4, when the zeolite has a silica-alumina ratio of 1 to 1000, Example 3 The start-up time was measured in the same manner. These results are summarized in Table 4.
[0057]
[Table 4]
(Comparative Example 1)
An example in which an oxide having a composition shown in Table 5 or 1% by weight of a noble metal supported on alumina, and 42 to 47 are used as the catalyst body 1 in place of the rare earth or transition metal supported on the zeolite of the present invention. 1 was installed in the reaction chamber 2 shown in FIG. From the reformed gas inlet 3, reformed gas having 8% carbon monoxide, 8% carbon dioxide, 20% water vapor and the remaining hydrogen was introduced at a flow rate of 10 liters per minute. After controlling the reformed gas temperature and reacting with the catalyst body 1, the composition of the gas discharged from the reformed gas outlet 4 was measured by gas chromatography. The minimum value of CO concentration when the temperature is changed and the methane concentration in the gas after the reaction at a catalyst temperature of 400 ° C. are measured, and the operation of starting the apparatus again after stopping the apparatus is repeated 10 times. The minimum value of the concentration was measured to confirm the change in the activity of the catalyst. These results are summarized in Table 5.
[0059]
[Table 5]
(Comparative Example 2)
Instead of the Pt / Ce / Y type zeolite shown in Sample 4 in Table 1 used in Example 1, 1% by weight of Pt was supported on cerium oxide, and the cordierite honeycomb was coated in the same manner as in Example 1, It installed in the reaction chamber 2 shown in FIG.
[0061]
From the reformed gas inlet 3, introduction of reformed gas with 8% carbon monoxide, 8% carbon dioxide, 20% water vapor, and the remainder hydrogen is started at a flow rate of 10 liters per minute. It was 55 minutes when the time (start-up time) until the CO concentration rose below 1% was measured.
[0062]
(Comparative Example 3)
In Comparative Example 2, as shown in FIG. 2, an air supply unit 14 is provided on the upstream side of the catalyst body 11, and the start-up time is measured in the same manner as in Comparative Example 2 while supplying air at a flow rate of 0.2 liters per minute. It was 40 minutes.
[0063]
Thus, the following fact is supported when the catalyst body in this comparative example is used. A complex oxide of iron and chromium containing no precious metal cannot sufficiently reduce CO, and the copper-zinc catalyst has a high initial activity, but the activity decreases remarkably when repeated starting and stopping. Moreover, the activity of noble metal supported on alumina is not reduced, but the methane concentration at 400 ° C. is high. Also, the start-up time was shortened by using zeolite.
[0064]
As is apparent from the above description, the hydrogen purifier of the present invention has improved the durability of the CO shift catalyst body, and operates stably even when the apparatus is repeatedly started and stopped. Time can be shortened.
[0065]
【Effect of the invention】
As is clear from the above description, the present invention can provide a hydrogen purifier having high CO removal efficiency that can be easily heated at the start, for example.
[Brief description of the drawings]
1 is a schematic longitudinal sectional view showing a configuration of a hydrogen generator including a hydrogen purifier according to Embodiment 1 of the present invention. FIG. 2 is a hydrogen generator including a hydrogen purifier according to Embodiment 2 of the present invention. Schematic longitudinal cross-sectional view showing the structure
DESCRIPTION OF SYMBOLS 1,11 Catalyst body 2,12 Reaction chamber 3,13 Reformed gas inlet 4,14 Reformed gas outlet 5,16 Diffusion plate 6,17 Heat insulating material 15 Air supply part
Claims (5)
Priority Applications (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2001176571A JP4867084B2 (en) | 2001-06-12 | 2001-06-12 | Hydrogen purification equipment |
| US10/239,965 US7147680B2 (en) | 2001-01-26 | 2002-01-24 | Hydrogen purification apparatus and method and fuel cell power generation system and method |
| CN200910160449A CN101712461A (en) | 2001-01-26 | 2002-01-24 | Hydrogen purification device and fuel cell power generation system |
| EP02710339A EP1354853A4 (en) | 2001-01-26 | 2002-01-24 | Hydrogen purification device and fuel cell power generation system |
| CN02800372A CN1457320A (en) | 2001-01-26 | 2002-01-24 | Hydrogen purification device and fuel cell power generation system |
| PCT/JP2002/000487 WO2002059038A1 (en) | 2001-01-26 | 2002-01-24 | Hydrogen purification device and fuel cell power generation system |
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| JP2001176571A JP4867084B2 (en) | 2001-06-12 | 2001-06-12 | Hydrogen purification equipment |
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| JP4867084B2 true JP4867084B2 (en) | 2012-02-01 |
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| US6932848B2 (en) * | 2003-03-28 | 2005-08-23 | Utc Fuel Cells, Llc | High performance fuel processing system for fuel cell power plant |
| JP5389314B2 (en) * | 2005-10-05 | 2014-01-15 | 株式会社日立製作所 | Shift catalyst and preparation method thereof |
| CN110681411B (en) * | 2018-07-05 | 2023-07-25 | 中国石油天然气股份有限公司 | Bimetallic catalytic reforming catalyst containing FAU type molecular sieve |
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| JPH082902A (en) * | 1994-06-15 | 1996-01-09 | Idemitsu Kosan Co Ltd | Production of hydrogen-containing gas for fuel cell |
| JP2000302409A (en) * | 1999-04-20 | 2000-10-31 | Matsushita Electric Ind Co Ltd | Apparatus for generating hydrogen |
| WO2000054879A1 (en) * | 1999-03-18 | 2000-09-21 | Matsushita Electric Works, Ltd. | Catalyst for water gas shift reaction, method for removing carbon monoxide in hydrogen gas and electric power-generating system of fuel cell |
| JP3473898B2 (en) * | 1999-04-22 | 2003-12-08 | 松下電器産業株式会社 | Hydrogen purification equipment |
| DE10013895A1 (en) * | 2000-03-21 | 2001-10-04 | Dmc2 Degussa Metals Catalysts Cerdec Ag | Water gas shift reaction, useful in mobile unit in vehicle for removing carbon monoxide from gas mixture containing hydrogen for fuel cell, uses catalyst based on noble metal coating on inert carrier |
| JP2002079102A (en) * | 2000-09-07 | 2002-03-19 | Mitsui Chemicals Inc | Catalyst for shift reaction and reaction method |
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