リンガンド は 違い を 生み出す! エチレンポリメリゼーション中のCrVI/SiO2フィリップス触媒に関する分子洞察
Caterina Barzan1, Alessandro Piovano1, Luca Braglia1,2
1Department of Chemistry, NIS Interdepartmental Center and INSTM Reference Center, University of Turin , Via G. Quarello 15A, Turin I10135, Italy.
Journal of the American Chemical Society
|August 23, 2017
まとめ
この研究は,酸化副産物と相互作用する6倍調整の二価クロム (Cr) イオンが,エチレンポリメリゼーションのフィリップス触媒の活性部位であることを明らかにし,以前の理論に異議を唱える.
科学分野:
- 異質な触媒
- ポリマー化化学
- 材料科学
背景:
- フィリップス触媒 (Cr/SiO2) はエチレンポリメリゼーションに不可欠です.
- 活性クロム (Cr) 部位とその調整を理解することは,触媒の性能を最適化するための鍵です.
- 以前のモデルは"裸"または低調整Cr種を活性サイトとして提案しました.
研究 の 目的:
- エチレンポリメリゼーション中のCrVI/SiO2におけるCr部位の分子構造変化を,オペラント感受性スペクトロスコーピーを用いて調査する.
- エチレンによるCr還元と,その後のポリメリゼーションプロセスを区別する.
- 触媒活動に責任を負う特定のCr種と調整環境を特定する.
主な方法:
- Cr 部位をモニターするために,オペラントに敏感なスペクトロスコーピック技術を使用した.
- クロマート還元とポリメリゼーションを分離するために,慎重に制御された実験パラメータ.
- ポリメリゼーション副産物とのCrサイトの相互作用を分析した.
主要な成果:
- エチレンポリメリゼーションの主な活性部位として6倍調整の二価クロイオンを特定した.
- 主にメチルフォーム酸と相互作用する活性サイトを観察した.
- ポリメリゼーション中に存在する未縮小CrVIと観衆CrII/CrIII種が見つかりました.
結論:
- "裸"クローム種仮説に異議を唱え,代わりに活性サイトは外部酸素リガンドと調整されたクロームイオンであると提案する.
- これらの柔軟な酸素化リガンドは,同質的触媒における補助リガンドに類似して重要な役割を果たしている.
- フィリップス触媒に対するエチレンポリメリゼーションに関する新しい機械的洞察を提供します.
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