在γ-Al2O3上的精确原子Pd3纳米集群的化学激活支持转移化反应
Siddhant Singh1, Dami Wi1, Kholoud E Salem2
1Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan S7N 5C9, Canada. robert.scott@usask.ca.
使用化物还原剂的纳米集群的化学激活比热方法更好地控制尺寸和物种化. 这种方法通过为特定反应量身定制纳米集群属性来提高催化剂性能.
科学领域:
- 不同质的催化剂.
- 纳米材料科学科学 纳米材料科学
- 表面化学 表面化学
背景情况:
- 固体支上的精确原子纳米集群是模拟异质催化剂的关键.
- 配体去除 (激活) 对于增强纳米集群支持相互作用至关重要.
- 传统的热激活可以导致对纳米集群大小和物种的控制较差.
研究的目的:
- 在温和条件下研究在γ-Al2O3支上[Pd3(μ-Cl) ((μ-PPh2) 2 ((PPh3) 3) + (Pd3) 纳米集群的化学激活.
- 评估以化物为基础的还原剂 (NaBH4,LiBH4,LiAlH4) 作为热处理的替代品.
- 将激活方法与纳米集群结构演变,物种化和催化性能相关联.
主要方法:
- 在γ-Al2O3.3上支持Pd3纳米集群的合成.
- 使用NaBH4,LiBH4和LiAlH4.4进行化学激活.
- 使用X射线吸收光谱学 (XAS),X射线光电子光谱学 (XPS),扫描传输电子显微镜与能量分散式X射线光谱学 (STEM-EDX) 映射以及固态核磁共振 (NMR) 光谱学进行表征.
- 催化试验在转移化中进行过甲的催化试验.
主要成果:
- 化降解剂有效地去除了氨酸和化连接物.
- 纳米集群大小的增长与使用的化量相关;观察到酸盐副产品.
- LiAlH4处理产生了Pd单原子位点和激活纳米集群的混合物,其尺寸增长最小.
- 较小的Pd纳米集群显示出较高的选择性,但与较大的纳米颗粒相比,在跨-cinnamaldehyde化中的活性较低.
结论:
- 化学激活为支持的纳米集群催化剂提供了可控制的替代热方法.
- 减少剂的选择影响了纳米集群的物种化,尺寸控制和由此产生的催化性能.
- 通过化学激活量身定制纳米集群大小和物种化对于优化催化选择性和活性至关重要.
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