标记揭示了岩催化剂中的配对活性位点
Kuizhi Chen1, Anya Zornes2, Vy Nguyen3
1National High Magnetic Field Laboratory, Tallahassee, Florida32310, United States.
Journal of the American Chemical Society
|August 31, 2022
概括
鉴定石催化剂的特征,揭示了扩展碳化合物化学的两个配对活性位点. 这些位点依赖于协调,影响反应性和稳定性,影响催化剂性能.
科学领域:
- 材料科学
- 催化剂
- 固态核磁共振光谱
背景情况:
- 石催化剂对于碳化合物化学至关重要,但它们的活性位点结构需要更深入的理解,以便更广泛地应用.
- 目前在特征活性位点方面的局限性阻碍了先进的岩催化剂的开发.
- 水热稳定性和活性位点分布是催化剂寿命和性能的关键因素.
研究的目的:
- 描述H-ZSM-5热催化剂中的活性部位结构和分布.
- 调查框架协调对活性点配对和水热稳定性的影响.
- 阐明伴侣活性位点在石催化活性中的作用.
主要方法:
- 在17O丰富的H-ZSM-5上使用了一套同核和异核NMR相关性实验.
- 使用计算 DFT 计算来支持实验结果.
- 应用室温同位素交换和17O → 27Al极化转移用于位置识别.
主要成果:
- 至少确定了两种类型的配对活性位点,取决于Al (IV) - 1和Al (IV) - 2位点的数量.
- 证明配对位点分布受合成和合成后修饰的影响,而不仅仅是Si/Al比率.
- 发现Al(IV) - 1/Al(IV) - 2对比Al(IV) - 1/Al(IV) - 1对更接近酸基.
- 表明框架Al对比孤立位点更容易发生水解.
- 已确认同质的17O纳入焦岩框架,但不包括框架外的Al物种.
结论:
- -1/-2配对的位点是协同作用的,在各种反应中增强反应性.
- 了解和控制配对的活性位点是推动热带石催化剂设计的关键.
- 框架Al配对影响水热稳定性,为催化剂的耐用性提供了洞察力.
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