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TiIVの動的再構成と閉じ込め 制御 オレフィンエポキシデーション触媒 二次元ゼオタイプ
Nicolás A Grosso-Giordano1, Adam S Hoffman2, Alexey Boubnov2
1Department of Chemical and Biomolecular Engineering , University of California, Berkeley , Berkeley , California 94720 , United States.
Journal of the American Chemical Society
|April 9, 2019
まとめ
シリケートポケット内のチタン触媒部位の閉じ込めは,エントロピックバリアを減らすことによってオレフィンエポキシデーション率を大幅に高めます. ダイナミック・リオーガナイゼーションは 限られた場所の利用に有利で 表面反応制御の新たな手段を 提供します
科学分野:
- 異質な触媒
- 表面化学
- 材料科学
背景:
- オレフィンエポキシデーションは重要な産業プロセスです.
- アクティブサイト環境の制御は,触媒性能に影響します.
- チタンシリケート材料は調整可能な触媒特性を持っています.
研究 の 目的:
- オレフィンエポキシデーションのための分離されたチタン (IV) 触媒センターに対するダイナミック・コンファインメントの影響を調査する.
- 活性部位の位置と再編成が触媒活動に与える影響を明らかにする.
- 浅い表面のポケットの潜在能力を探求する.
主な方法:
- 制御された封じ込め (非封じ込め対12-MRポケット) のシリケート中心のチタンの合成.
- ターチルブチル水酸化物を用いたサイクロヘクセンエポキシデーションの運動研究.
- 電子構造分析のための密度関数理論 (DFT) 計算.
- 活性化パラメータの熱力学分析 (エンタルピーとエントロピー).
主要な成果:
- 12MRポケット内の限られたTi (IV) 部位は,限られた部位と比較してエポキシデーションの速度を約5倍に増加させた.
- ダイナミックな再編は,限られたアクティブサイトを優先的に占有することにつながった.
- 閉じ込めはエントロピックバリアを減少させ,反応物質の結合と移行状態の形成を容易にした.
- アクティベーションエンタルピーは一定であり,エントロピーの変化は速度の違いを説明した.
結論:
- 浅い表面のポケットに部分的に閉じ込められることは,エントロピー効果によって触媒反応性を高めます.
- ダイナミックな再編成は,活発なサイトを有利な閉じ込められた環境に導く上で重要な役割を果たします.
- このアプローチは,表面の反応性を制御するための新しい戦略を提示します.
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