ルチルで支えられた黄金のクラスターの金属の角原子は,水ガスシフト触媒の際に支配的な活性部位です
W Damion Williams1, Mayank Shekhar, Wen-Sheng Lee
1School of Chemical Engineering, Purdue University, West Lafayette, Indiana 47907, USA.
Journal of the American Chemical Society
|September 22, 2010
まとめ
二酸化チタンの黄金触媒は,水ガスシフト反応 (WGS) で高い活性を示しています. 黄金のクラスターごとに発生する割合は,1 nm 以上の粒子の大きさに関係なく,コーナー原子が主な活性部位である.
科学分野:
- カタリシス カタリシス カタリシス
- マテリアルサイエンス 材料科学
- 表面化学について
背景:
- 水ガスシフト反応 (WGS) は,水素生成に不可欠である.
- 二酸化チタン (TiO2) に支えられた金 (Au) 触媒は,WGS反応において有意な活性を示します.
- Au/TiO2の触媒性能は,金粒子の大きさに敏感であることが知られている.
研究 の 目的:
- WGS反応における金粒子の大きさと触媒活性との関係を調査する.
- Au/TiO2触媒の特定の活性部位を特定するために.
- WGS反応速度の観測されたサイズ依存性を説明する物理モデルを開発する.
主な方法:
- Au/TiO2触媒の準備のための無孔のモデルサポートを使用しました.
- 精密な金粒子のサイズ分布分析のために,伝送電子顕微鏡 (TEM) を採用した.
- 金原子の協調を触媒活動と相関させる物理モデルを開発した.
主要な成果:
- 120°Cで高いWGS反応速度 (秒あたりmol Auあたり0.1mol COまで) を達成した.
- 金の1モルあたりの触媒速度は,より小さな粒子の粒子のサイズに強く依存することを実証した.
- 主要な活性サイトとして金角原子 (隣人数<7) を特定した.
- コーナーサイトの数が1nm以上の粒子の場合は一定であり,サイズ独立の割合につながることが観察されました.
結論:
- WGS反応におけるAu/TiO2の触媒活動は,主にコーナーゴールド原子によって制御されます.
- 1ナノメートル以上の金粒子の場合,クラスタごとに活性部位の数が一定であり,その結果,大きさに依存しない反応速度が生じます.
- この研究は,サポートされたゴールド触媒の構造活動関係に関する基本的な洞察を提供します.
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