铜交换的查巴酸盐中成分依赖活性位点的氧化和动力性质,用于直接甲-甲醇氧化
Andreas Brenig1,2, Jörg W A Fischer3, Daniel Klose3
1Institute for Chemical and Bioengineering, ETH Zurich, Vladimir-Prelog-Weg 1-5/10, 8093, Zurich, Switzerland.
Angewandte Chemie (International ed. in English)
|July 26, 2024
概括
铜 - 沙巴酸氧化石的甲氧化性能根据铜负载和Si/Al比率而有所不同. 单体铜位增强甲醇选择性和效率,而二元位不会影响激活能量.
科学领域:
- 催化剂是一种催化剂.
- 材料科学 材料科学 材料科学
- 化学工程是化学工程的重要组成部分.
背景情况:
- - 哈巴酸地热石是甲氧化有前途的催化剂.
- 催化剂结构,活性位点和性能之间的关系尚未完全理解.
研究的目的:
- 调查Si/Al比率和Cu负载对Cu-chabazite热石在甲氧化中的性能的影响.
- 为了将催化活性和选择性与活性铜位点的性质相关联.
主要方法:
- 在插头流反应器中进行了甲氧化反应.
- 采用了现场和操作的光谱技术,包括里埃变换红外 (FTIR),X射线吸收光谱 (XAS),电子磁共振 (EPR),拉曼,紫外线可见 (UV-Vis) 和光发光 (PL).
主要成果:
- 降低Cu负载将反应性转移到更高的温度,增加甲醇选择性和铜效率.
- 低Si/Al比率和低Cu负载的单体Cu活性位点 (赤裸Cu2+和[CuOH]+) 被确定为提高性能的关键.
- 在较高Si/Al比率或Cu负载下形成的二氧化[Cu2(μ-O) ]2+部分逆转了这些趋势.
- 单质Cu物种的明显激活能量随着Si/Al比率的增加而下降,而二度中心不受影响.
结论:
- 铜活性位点的性质和物种化 (单体与二体) 极大地控制了Cu-chabazite热石的甲氧化性能.
- 优化Cu负载和Si/Al比率对于最大限度地提高甲醇选择性和催化剂效率至关重要.
- 了解活性位点的动态,为设计选择性甲氧化改善的催化剂提供了洞察力.
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