Buendía G M, Rikvold P A
Physics Department, Universidad Simón Bolívar, Apartado 89000, Caracas 1080, Venezuela.
Phys Rev E Stat Nonlin Soft Matter Phys. 2013 Jul;88(1):012132. doi: 10.1103/PhysRevE.88.012132. Epub 2013 Jul 25.
We present results of kinetic Monte Carlo simulations of a modified Ziff-Gulari-Barshad model for the reaction CO+O → CO(2) on a catalytic surface. Our model includes impurities in the gas phase, CO desorption, and a modification known to eliminate the unphysical O poisoned phase. The impurities can adsorb and desorb on the surface, but otherwise remain inert. In a previous work that did not include CO desorption [Buendía and Rikvold, Phys. Rev. E 85, 031143 (2012)], we found that the impurities have very distinctive effects on the phase diagram and greatly diminish the reactivity of the system. If the impurities do not desorb, once the system reaches a stationary state, the CO(2) production disappears. When the impurities are allowed to desorb, there are regions where the CO(2) reaction window reappears, although greatly reduced. Following experimental evidence that indicates that temperature effects are crucial in many catalytic processes, here we further analyze these effects by including a CO desorption rate. We find that the CO desorption has the effect to smooth the transition between the reactive and the CO rich phase, and most importantly it can counteract the negative effects of the presence of impurities by widening the reactive window such that now the system remains catalytically active in the whole range of CO pressures.
我们展示了对催化表面上 CO + O → CO₂ 反应的改进 Ziff-Gulari-Barshad 模型进行动力学蒙特卡罗模拟的结果。我们的模型包括气相中的杂质、CO 解吸以及一种已知可消除非物理 O 中毒相的修正。杂质可以在表面吸附和解吸，但除此之外保持惰性。在先前一项未包括 CO 解吸的工作中 [Buendía 和 Rikvold，《物理评论 E》85，031143 (2012)]，我们发现杂质对相图有非常独特的影响，并大大降低了系统的反应活性。如果杂质不解吸，一旦系统达到稳态，CO₂ 的生成就会消失。当允许杂质解吸时，存在一些区域，其中 CO₂ 反应窗口会重新出现，尽管大大缩小了。根据表明温度效应在许多催化过程中至关重要的实验证据，在这里我们通过纳入 CO 解吸速率进一步分析这些效应。我们发现 CO 解吸具有使反应相和富 CO 相之间的转变变得平滑的作用，最重要的是它可以通过拓宽反应窗口来抵消杂质存在的负面影响，使得现在系统在整个 CO 压力范围内都保持催化活性。
