arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0802.0553cond-mat.mtrl-sci
收藏

工艺相关压力条件下Pd(100)上CO氧化:第一性原理动力学Monte Carlo研究

CO oxidation on Pd(100) at technologically relevant pressure conditions: A first-principles kinetic Monte Carlo study

Jutta Rogal, Karsten Reuter, Matthias Scheffler

摘要:

近年来,氧化物的形成对过渡金属多相氧化催化活性的影响引起了热烈的讨论。在更贵的过渡金属(如Pd、Pt或Ag)上,常见的本体氧化物的低稳定性主要表明亚纳米薄氧化物膜(所谓的表面氧化物)作为潜在的候选物,其可以在代表技术氧化催化的气相条件下稳定。我们解决了这个问题的Pd(100)模型催化剂表面的第一性原理动力学蒙特卡罗(kMC)模拟,评估稳定的表征(sqrt{5} x sqrt{5})R27表面氧化物在稳态CO氧化。我们的研究结果表明,在环境压力条件下,表面氧化物是稳定的表面CO:O2分压比附近的催化最相关的化学计量进料(p(CO):p(O2)= 2:1)。精确的值敏感地取决于温度,使得局部压力和温度波动都可能在环境化学计量条件下的稳态操作期间引起氧化物相的连续形成和分解。

英文摘要:

The possible importance of oxide formation for the catalytic activity of transition metals in heterogenous oxidation catalysis has evoked a lively discussion over the recent years. On the more noble transition metals (like Pd, Pt or Ag) the low stability of the common bulk oxides suggests primarily sub-nanometer thin oxide films, so-called surface oxides, as potential candidates that may be stabilized under gas phase conditions representative of technological oxidation catalysis. We address this issue for the Pd(100) model catalyst surface with first-principles kinetic Monte Carlo (kMC) simulations that assess the stability of the well-characterized (sqrt{5} x sqrt{5})R27 surface oxide during steady-state CO oxidation. Our results show that at ambient pressure conditions the surface oxide is stabilized at the surface up to CO:O2 partial pressure ratios just around the catalytically most relevant stoichiometric feeds (p(CO):p(O2) = 2:1). The precise value depends sensitively on temperature, so that both local pressure and temperature fluctuations may induce a continuous formation and decomposition of oxidic phases during steady-state operation under ambient stoichiometric conditions.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑