Catalytic partial oxidation of methane on platinum investigated by spatial reactor profiles, spatially resolved spectroscopy, and microkinetic modeling
Catalytic partial oxidation of methane on platinum investigated by spatial reactor profiles, spatially resolved spectroscopy, and microkinetic modeling
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DOI：
10.1016/j.jcat.2012.08.022
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发表时间：
2013-01-01
影响因子：
7.3
通讯作者：
Horn, Raimund
中科院分区：
文献类型：
--
作者：
Korup, Oliver;Goldsmith, Claude Franklin;Horn, Raimund
利用空间分辨剖面测量、拉曼光谱、电子显微镜和微观动力学模型研究了甲烷在铂上的催化部分氧化反应。通过铂涂层泡沫催化剂测量的物种分布显示出双区结构：反应速率的突然变化将反应器入口处的快速放热氧化化学与缓慢吸热重整化学分开。空间分辨拉曼光谱和电子显微镜证实，机理变化的位置可能与铂的迁移和碳质沉积物的形成有关，阻止了重整区大部分活性铂中心的形成。物种分布采用准2D非均相模型进行模拟，该模型包括热量和质量传输限制，以及两种最新的化学动力学机制。虽然这两种机理都与氧分布定量一致，但这两种机理对部分氧化和完全氧化之间的支化比以及表面位置覆盖率的预测有很大不同。实验观察到的反应速率的变化归因于碳的形成，由于不包括碳-碳偶联反应，因此该机制无法再现。(C)2012 Elsevier Inc.保留所有权利。
Spatially resolved profile measurements, Raman spectroscopy, electron microscopy, and microkinetic modeling have been used to study the catalytic partial oxidation of methane on Pt. The measured species profiles through Pt coated foam catalysts exhibit a two-zone structure: an abrupt change in reaction rates separates the fast exothermic oxidation chemistry at the entrance of the reactor from the slow endothermic reforming chemistry. Spatially resolved Raman spectroscopy and electron microscopy confirm that the position of the mechanistic change could be correlated with Pt transportation and formation of carbonaceous deposits blocking the majority of active Pt sites in the reforming zone. The species profiles were simulated using a pseudo-2D heterogeneous model, which includes heat and mass transport limitations, and two state-of-the-art chemical kinetic mechanisms. Although both mechanisms are in quantitative agreement with the oxygen profiles, the two mechanisms differ substantially in their predictions of the branching ratio between partial and complete oxidation, as well as surface site coverages. The experimentally observed change in reaction rates is attributed to carbon formation, which the mechanisms are unable to reproduce, since they do not include carbon-carbon coupling reactions. (c) 2012 Elsevier Inc. All rights reserved.