ゼオライト結晶化中の無形マトリックスにおける短距離秩序の調節反応力学
Ching-Tien Chen1, Kenta Iyoki1, Peidong Hu1,2
1Department of Chemical System Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Journal of the American Chemical Society
|July 16, 2021
まとめ
ゼオライトの結晶化を理解するには,無形マトリックス形成を調査する必要があります. 反応物質の選択と凝縮運動は,短距離の順序を決定的に影響し,ゼオライト核化頻度と合成に影響します.
科学分野:
- 材料科学
- 化学について
- クリスタルグラフィー
背景:
- ゼオライト結晶は,乱れから秩序への変換であり,アモルフなマトリックス,特に密度の高い水素で核形成を観察する難しさのために,十分に理解されていません.
- 合成条件,無形種,ゼオライト結晶化行動の関係は不明である.
研究 の 目的:
- 異なるシリコン反応剤を用いた密度の高い水素ゲル系におけるアルミシリケートマトリクスの構造的進化を調査する.
- 変形マトリックス形成およびその後のゼオライト核形成における反応物質の反応性と凝縮運動の重要な役割を明らかにする.
主な方法:
- 密度の高いヒドロゲル系における構造進化の比較調査で,シリケート溶液とシリケート溶液をSi反応剤として使用した.
- 変化する反応条件 (温度,老化) の下で無形マトリックス形成と構造特性の分析.
主要な成果:
- 蒸発したシリカは,80°Cでアルミ酸ナトリウムと徐々に反応し,アルミ酸ナトリウムに富んだ4つ組の環と6つ組の環を持つ無形な固体を作り出し,ゼオライトX (FAU) の構成単位を形成した.
- ナトリウムシリケートとナトリウムアルミナートで即座に濃縮され,結晶化を阻害する安定した複雑なマトリックスを形成した.
- 加熱前に周囲の温度で反応物質の混合物を老化させると,短距離秩序が促進され,ゼオライト核化の頻度が増加した.
結論:
- 反応物質の選択と凝縮運動は,無形マトリックス内の短距離構造の形成に不可欠であり,ゼオライト核形成に直接影響する.
- 無形前体における特定の環構造の制御された形成は,効率的なゼオライトX (FAU) 結晶化の鍵です.
- 老化と反応条件を最適化すると,オーダーされた無形構造の形成が促進され,それによってゼオライト核化の頻度が増加します.
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