与其酸度相关的批量纳米化氧化物的结构研究
Hannah T Kreissl1, Molly M J Li1, Yung-Kang Peng1
1Department of Chemistry, University of Oxford , Oxford OX1 3QR, United Kingdom.
Journal of the American Chemical Society
|August 15, 2017
概括
化氧化物根据其纳米结构表现出可调节的酸性. 在纳米结构的氧化物中,灵活的Nb-O系统创建了易斯酸位,增强了催化应用.
科学领域:
- 材料科学
- 催化剂
- 固态化学
背景情况:
- 水合氧化物被认为是具有多种催化用途的有力固体酸.
- 这些材料的结构特征与产生的酸度之间的确切关系尚未完全理解.
研究的目的:
- 阐明水合氧化物中易斯和布伦斯特德酸位的特定结构属性.
- 将氧化系统的纳米结构和灵活性与其酸位密度和类型相关联.
主要方法:
- 使用稳定剂合成高表面积的纳米结构氧化物 (Nb2O5·nH2O).
- 批量氧化材料 (HNb3O8,无水H-Nb2O5) 的特性进行比较.
- 结构特征的分析,包括协调数和氧气空缺,以及它们与酸位识别的相关性.
主要成果:
- 易斯酸位点归因于低坐标的NbO5和NbO4位点,这是灵活的NbO6系统中氧气空缺的结果.
- 高表面积,纳米结构氧化物表现出明显的结构灵活性和较高的酸性位点密度.
- 散装材料和无水氧化物具有有限的结构灵活性,可检测到的酸性部位很少或不存在.
结论:
- Nb-O系统的结构灵活性,特别是在纳米结构的氧化物中,对于产生易斯酸位至关重要.
- 灵活的NbO6单位中的氧空缺是形成易斯酸度的关键.
- 材料形态 (纳米结构与散装) 和水分状态显著影响可用于催化剂的酸位的类型和度.
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