在Pt{111}上交换和,并通过表面敏感的高压技术研究其一氧化碳中毒
Max Montano1, Kaitlin Bratlie, Miquel Salmeron
1Department of Chemistry, University of California, Berkeley, 94720, USA.
Journal of the American Chemical Society
|October 5, 2006
概括
一氧化碳 (CO) 完全毒害 (111) 在低温下发生催化/交换. 在更高的温度下,CO会减缓但不会停止反应,这表明移动和活跃的表面模型.
科学领域:
- 表面科学是一门科学.
- 不同质的催化剂.
- 化学动力学 化学动力学
背景情况:
- (111) 是化反应的关键催化剂.
- 一氧化碳是一种已知的催化剂毒素.
- 了解二氧化碳中毒对于催化剂设计至关重要.
研究的目的:
- 研究一氧化碳 (CO) 对/ (H2/D2) 交换在 (111) 上的影响.
- 为了确定不同温度和压力下CO中毒的机制.
- 提出一个表面模型来解释观察到的催化活性.
主要方法:
- 在现场扫描道显微镜 (STM) 用于表面成像.
- 用X射线光电子光谱 (XPS) 分析表面组成.
- 总频率生成振动光谱 (SFG) 用于分子识别.
- 质谱测量用于检测反应产品.
主要成果:
- 在298K时,5mTorr的CO完全抑制了H2/D2交换,激活能量为5.3kcal/mol.
- 在353K,5mTorr的CO降低了反应速度的3个数量级,但并没有完全抑制HD的产生.
- XPS和SFG表示CO覆盖面和吸附点变化高达480K.
结论:
- 在低温下,二氧化碳通过形成一个有序的化学吸收层,起到完全毒性的作用.
- 在更高的温度下,二氧化碳的流动性允许持续的催化活性.
- 提出了一个由CO主导,移动和催化活性表面的模型.
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