循环烯吸附和对Pt的反应的能量{111) 通过低温微热量计
Ole Lytken1, Wanda Lew, Jonathan J W Harris
1Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, USA.
Journal of the American Chemical Society
|July 12, 2008
概括
循环烯在100K时完好无损地在Pt{111) 上吸附,但在281K时脱,形成吸附的2-循环烯. 测量了吸附热量和粘合概率,揭示了表面化学的洞察力.
科学领域:
- 表面科学是一门学科.
- 化学物理 化学物理
- 材料科学 材料科学 材料科学
背景情况:
- 了解碳化合物在金属表面的吸附行为对于催化是至关重要的.
- 环烯是研究涉及C-H键激活和脱反应的模型分子.
- (Pt) 是许多工业过程中的关键催化剂.
研究的目的:
- 为了研究循环二烯在白金{111}表面上的吸附.
- 为了确定吸附热和粘附概率作为覆盖的函数.
- 阐明在不同温度下对Pt{\displaystyle Pt}{\displaystyle Pt}{\displaystyle Pt}{\displaystyle Pt}{\displaystyle Pt}{\displaystyle Pt}{\displaystyle Pt}}{\displaystyle Pt}{\displaystyle Pt}{\displaystyle Pt}{\displaystyle Pt}{\displaystyle Pt}{\displaystyle Pt}{\displaystyle Pt}{\displaystyle Pt}{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text{\text}{\text{\text{\text{\text{\text{\text{\text}{\text}{\text{\text}{\text{\text}{\text{\text}\text{\text}\text{\text{\text{\text}}\text{\text{\text{\text}}\text{\text{\text}}\text{\text{\text}}}}\text{\text}}}}\text{\text}}}}
主要方法:
- 单晶吸附热量计被用来测量吸附度.
- 测量了粘合概率,以了解初始相互作用的动态.
- 在100300 K的温度范围内进行了实验.
主要成果:
- 在100K时,环烯通过二位数键连接完好地吸附,吸附热量为 (130 - 47 θ - 1250 θ2) kJ/mol.
- 这种完整的吸附产生了205kJ/mol的C-Pt西格玛键强度.
- 在281K时,环烯在吸附时脱水,形成吸附的2-环烯和H,吸附热量为 (174 - 700 θ + 761 θ2) kJ/mol.
- 发现低覆盖率 (>0.95) 的粘合概率在0.10 ML以下是温度独立的.
结论:
- 在Pt{111}上,环合的吸附状态是温度依赖的,从完整的吸附过渡到脱.
- 该研究提供了循环烯及其在Pt上脱产物的定量热力学数据 (形成度,键强度).
- 在研究条件下,高的初始粘附概率表明环素在Pt{111}上有效吸附.
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