クラスター化学:サイズに依存する反応性,反転溢出効果によって誘発される
Martin A Röttgen1, Stephane Abbet, Ken Judai
1Lehrstuhl für Physikalische Chemie I, Technische Universität München, Lichtenbergstrasse 4, 85748 Garching, Germany.
Journal of the American Chemical Society
|July 10, 2007
まとめ
パラジウム (Pd) クラスターのCO酸化率は,CO分子の配送に依存する. リバース・スピルオーバーは,より小さなPd(8) クラスターと,より大きなPd(30) クラスターに異なる影響を及ぼし,反応の確率に影響する.
科学分野:
- 異質なカタリシスである.
- 表面科学とは,地表科学のことである.
- ナノ素材 ナノ素材
背景:
- 支えられた金属クラスターのCO酸化を理解することは,触媒化にとって極めて重要です.
- 反応速度に対するCO拡散 (反転溢出効果) の役割は完全に理解されていません.
- 金属のクラスターのサイズに依存する触媒活動は,重要な研究分野である.
研究 の 目的:
- サイズで選択されたパラジウム (Pd) クラスターのCO酸化率を調査する.
- 異なるPdクラスタサイズの触媒活動に対する反転溢出効果の影響を決定する.
- 直流と拡散によって供給されるCOの反応確率を区分する.
主な方法:
- CO酸化を研究するためにパルス分子ビーム実験が使用されました.
- MgOフィルムに支えられたサイズ選択されたPdクラスター (Pd(8) とPd(30)) が使用されました.
- クラスターのカバーは,クラスターのサイズに関係なく,COフクロス比率を変更するために変化しました.
- コレクションゾーンモデルは,クラスターへのCOフローをシミュレートするために使用されました.
主要な成果:
- CO酸化率は,Pd(8) とPd(30) のクラスターのクラスターカバーによって異なる.
- 小規模なPd(8) クラスターの場合,反応確率は,CO供給方法 (直接または拡散) にかかわらず独立していた.
- より大きなPd(30) クラスターでは,反転溢出によって供給されたCOは,直接流量と比較して反応の確率を低下させた.
結論:
- リバース・スピルオーバーは,サポートされているPdクラスターのCO酸化率に大きな影響を与える.
- 反応確率に対する反転溢出の影響は,クラスタサイズに依存します.
- カタリストの設計では,CO拡散が反応動力学に与える影響を考慮して,最適な性能を実現する必要があります.
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