The Partial Oxidation of Methane Over Pd/Al2O3 Catalyst Nanoparticles Studied In-Situ by Near Ambient-Pressure X-ray Photoelectron Spectroscopy
The Partial Oxidation of Methane Over Pd/Al2O3 Catalyst Nanoparticles Studied In-Situ by Near Ambient-Pressure X-ray Photoelectron Spectroscopy
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DOI：
10.1007/s11244-015-0520-8
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发表时间：
2016-01
影响因子：
3.6
通讯作者：
Rachel Price;Tuǧçe Eralp-Erden;E. Crumlin;Sana Rani;Sonia Garcia;Richard A. P. Smith;Liam Deacon;C. Euaruksakul;G. Held
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文献类型：
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作者：
Rachel Price;Tuǧçe Eralp-Erden;E. Crumlin;Sana Rani;Sonia Garcia;Richard A. P. Smith;Liam Deacon;C. Euaruksakul;G. Held
用近常压X射线光电子能谱(NAP-XPS)原位研究了甲烷氧化催化剂的化学状态。制备了不同粒径(4~10 nm)的Al_2O_3负载Pd催化剂。这些催化剂暴露在类似于甲烷部分氧化制合成气的条件下，并用NAP-XPS和质谱仪进行同步监测。NAP-XPS数据显示，随着温度的升高，钯的氧化态发生了变化，从金属Pd0到PdO，再回到Pd0。质谱仪显示，当钯处于氧化相时，一氧化碳的生成量增加，在新形成的氢气存在下，金属被还原回来。观察到了颗粒尺寸效应，使得CH4在较低的温度下开始转化，较大尺寸的颗粒从6到10 nm。我们发现，所有的纳米颗粒在比多晶钯箔更低的温度下开始甲烷转化。
Near ambient-pressure X-ray photoelectron spectroscopy (NAP-XPS) is used to study the chemical state of methane oxidation catalysts in-situ. Al2O3–supported Pd catalysts are prepared with different particle sizes ranging from 4 to 10 nm. These catalysts were exposed to conditions similar to those used in the partial oxidation of methane (POM) to syn-gas and simultaneously monitored by NAP-XPS and mass spectrometry. NAP-XPS data show changes in the oxidation state of the palladium as the temperature increases, from metallic Pd0to PdO, and back to Pd0. Mass spectrometry shows an increase in CO production whilst the Pd is in the oxide phase, and the metal is reduced back under presence of newly formed H2. A particle size effect is observed, such that CH4conversion starts at lower temperatures with larger sized particles from 6 to 10 nm. We find that all nanoparticles begin CH4conversion at lower temperatures than polycrystalline Pd foil.