モレキュラーライブラリのCr前端のXANESから軌道分析と監督された機械学習によるフィリップス触媒の解読
David Trummer1, Keith Searles1, Alexander Algasov2,3
1Department of Chemistry and Applied Biosciences, ETH Zürich, Vladimir-Prelog-Weg 2, CH-8093 Zürich, Switzerland.
Journal of the American Chemical Society
|May 11, 2021
まとめ
この研究では,機械学習とカスタマイズされたクロム (Cr) 分子複合体を用いて,触媒の表面部位を分析する新しい方法を開発しました. フィリップス触媒のクロム酸化状態と局所環境を正確に予測する.
科学分野:
- 異質な触媒
- 材料科学
- スペクトロスコーピー
- コンピュータ化学
背景:
- 異質な触媒,特にフィリップス触媒 (CrO3/SiO2) の表面部位を特徴づけることは,数十年にわたる研究を経て依然として重要な課題である.
- 既存のCrKエッジX線吸収近辺構造 (XANES) 分析方法は,実際の表面部位を正確に表さない基準材料を使用しています.
研究 の 目的:
- 調整された分子クロム複合体のためのCrK-エッジ XANESスペクトルの包括的なライブラリを作成します.
- クロミウムの酸化状態,調整環境,およびリガンドタイプを予測するための正確な記述器を確立する.
- 異なるプロセス段階におけるフィリップス触媒におけるサイト分布を決定するために,これらの記述子を適用する.
主な方法:
- 異なる酸化状態,協調性,結合強度を持つ一連の分子Cr複合体を合成し,特徴づけました.
- 実験的なCrKエッジXANESスペクトルを収集し,電子トランジションを理解するためにエッジ前の特徴を分析しました.
- 理論上のXANESスペクトルを生成し,ExtraTreesの機械学習アルゴリズムを訓練しました.
主要な成果:
- XANESのプレエッジ機能の定量分析により,電子交換の相互作用に関する洞察が明らかになりました.
- 機械学習モデルは,スペクトルディスクリプターを使用して,Cr酸化状態,原子間距離,およびリガンドタイプを成功裏に予測しました.
- フィリップス触媒の分析では,炭化水素暴露後のCr (VI) からCr (II) とCr (III) に,エチレン暴露後のCr (III) からCr (VI) に移行することが示された.
結論:
- 実験的なXANESスペクトルと理論的なXANESスペクトルを機械学習と組み合わせた新しいアプローチにより,触媒表面の正確な特徴づけが可能です.
- この研究は,異なる条件下でフィリップス触媒におけるクロームの種化と場所分布の詳細な理解を提供します.
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