Cu-CHA deNOx触媒の動作:Operando XASとXESによって監視される温度依存のNH3補助選択的触媒減量
Kirill A Lomachenko1,2, Elisa Borfecchia1, Chiara Negri1
1Department of Chemistry, NIS Centre and INSTM Reference Center, University of Turin , via P. Giuria 7, 10125 Turin, Italy.
Journal of the American Chemical Society
|August 18, 2016
まとめ
この研究は,アンモニア選択的触媒還元 (NH3-SCR) 中のCu-CHAゼオライトにおける銅活性部位の2つの異なる行動を示しています. 移動性銅種は低温で支配的であり,フレームワークで調整された銅サイトは高温NH3-SCRを駆動します.
科学分野:
- キャタリシス
- 材料科学
- 環境化学
背景:
- 小孔のCu-CHAゼオライトは,窒素酸化物を除去するためのNH3選択的触媒還元 (SCR) で高い性能を示す.
- SCRメカニズムと銅の活性部位を理解することは,触媒設計を最適化するために不可欠です.
研究 の 目的:
- NH3-SCR中のCu-CHAにおけるCu活性部位の原子スケールでの振る舞いを調査する.
- 銅の種化と流動性を,温度範囲内の触媒活動と相関させる.
主な方法:
- オペランドX線吸収光譜 (XANES,EXAFS) とX線放射光譜 (XES) が使用された.
- 150~400°Cの間のNH3-SCR中のCu-CHA触媒のインサイトモニタリング
主要な成果:
- 温度に基づいて2つの異なるCu活性部位の行動が特定されました.
- 低温 (<200°C) では,移動性NH3塩化Cu (I) /Cu (II) 種が優勢である.
- 高温 (>250 °C) では,フレームコーディネート Cu ((II) サイトが支配的になり,触媒活性が増加します.
結論:
- この研究では,NH3-SCR中のCu-CHAにおける銅の活性部位の温度依存の進化を明らかにした.
- 移動性銅種はより低い温度で活性化しますが,フレームワーク調整 Cu ((II) サイトは高温SCR性能の鍵です.
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