成果報告書詳細
管理番号20120000000397
タイトル*平成23年度中間年報 固体高分子形燃料電池実用化推進技術開発 基盤技術開発 定置用燃料電池システムの低コスト化のためのMEA高性能化(高活性・高耐久性・低S/C燃料改質触媒の開発と評価)
公開日2012/7/11
報告書年度2011 - 2011
委託先名国立大学法人山梨大学
プロジェクト番号P10001
部署名新エネルギー部
和文要約和文要約等以下本編抜粋:
1.研究開発の内容及び成果等
(1)今年度の研究開発の目標
本研究開発は、定置用燃料電池システムの燃料改質器に現在用いられているCO 選択酸化触媒(PROX 触媒)をそのまま置換できる高活性・高耐久なCO 選択メタン化触媒を開発することを目的としている。これまで我々は、Ni-Al 酸化物系CO 選択メタン化触媒がPROX 触媒より高い入口CO 濃度0.8?1.0%においても、99.0?99.9%の優れたCO 除去性能と50%を上回る反応選択性を広い温度域で示すことを見いだしている。しかし、500 時間規模の連続運転をこれら触媒に実施したところ、CO 除去性能と反応選択性、特に後者が、時間と伴に大きく低下することが認められた。本触媒を実用に供するためには、燃料改質器からの要求性能を実用耐久期間に亘り維持する耐久性を触媒改良により実現する必要がある。
昨年度の研究開発では、このCO 選択メタン化触媒が示す高い反応選択性とその劣化が、共に製造過程で触媒に残留した塩素の作用であることを見出した。さらに塩素の詳細な選択性発現機構を検討した結果、塩素と同様の作用を示す安定な添加剤を見出すことで耐久性向上が期待できること、また添加剤の選定はCO2 流通下で吸着CO 生成の有無をFTIR で評価することにより容易に判断できること等を明らかにした。本年度は、FTIR 評価法を用いて塩素に変わる安定な新規添加剤を探索し、その触媒耐久性向上に対する効果を500 時間の長期耐久性試験により示すことを目標とした。
英文要約Title: Development of PEFC Technologies aiming for Practical Application/Base Technology/R&D on PEFC components for reducing cost and improving performance of residential systems (FY2010-FY2012) FY2011 Annual Report
The aim of the present study is development of highly active and selective catalyst for CO selective methanation、 which can substitute a conventional preferential oxidation of CO process for a residential PEFC system. We have already developed Ni-Al oxide-based catalyst、 which can remove high concentration of CO (inlet: 0.8-1.0%) involved in reformate gas with 99.9% conversion and more than 50% selectivity. However、 significant decrease in selectivity for CO methanation during durability test was occurred by unfavorable elimination of chlorine residue of the catalyst. In this fiscal year、 a new effective and stable additive for improvement of the selectivity of catalyst was sought through “FTIR screening method”. Durability test for catalyst was carried out for 500 h. ・To clarify the essential durability of Ni-Al oxide catalyst、 which did not contain chlorine、 durability test was carried out. Contrary to our initial expectations、 decrease in CO conversion was observed. The deactivation manner of the catalyst without chlorine was different with the chlorine containing one; in the case of the catalyst without chlorine、 methane formation decreased with time on stream、 while for chlorine containing one the opposite trend was observed. This result indicated that active site of the catalyst without chlorine was poisoned or covered by something during the reaction measurement. By various characterization of the spent catalysts、 metal surface area、 BET surface area、 Ni particle size were not changed、 however、 carbonaceous species deposited on the catalyst was observed. It is well known that、 carbonaceous species are easily deposited on Ni-metal catalyst during CO hydrogenation condition. In this study、 we developed multi-metal-component catalyst、 which can remove CO at lower temperature and avoid carbon deposition in some extent.・We found the relationship between CO2 dissociation observed by FTIR measurement and CO2 methanation activity in the real reaction condition. We found vanadium acid was the most promising candidate for additive through the test of various elements. By the investigation of preparation for vanadium added Ni・Al oxide catalyst、 it was found that introduction of vanadium into alumina support by co-precipitation was the best method. ・By the durability test for the vanadium added catalysts, any decrease in selectivity was not observed. In the case of monolithic type catalyst、 decrease in CO removal with time was observed especially at high concentration of inlet CO、 however、 in the case of pellet type ones、 the deactivation was suppressed dramatically. ・Monolithic catalyst has two important advantages compared to the conventional pellet type catalyst; excellent thermal stability and significant reduction of required amount of catalyst. In this study、 catalyst-coating method for metal monolith was investigated. By our developed method、 the monolith was coated by the catalyst powder successfully and any defect cell was not observed.
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