Sulfation of a PdO(101) methane oxidation catalyst: mechanism revealed by first principles calculations
Sulfation of a PdO(101) methane oxidation catalyst: mechanism revealed by first principles calculations
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PdO(101)甲烷氧化催化剂的硫酸化：第一性原理计算揭示的机理
DOI：
10.1039/c8cy02096e
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发表时间：
2019
影响因子：
5
通讯作者：
Nakanishi Hiroshi
中科院分区：
文献类型：
--
作者：
Arevalo Ryan Lacdao;Aspera Susan Menez;Nakanishi Hiroshi
PdO有效地催化甲烷的氧化，但极大地遭受硫中毒，降低了其催化活性。在这项工作中，第一性原理计算进行，以揭示PdO（101）硫酸化的机制，以及如何改变甲烷活化的活性位点上形成的SOy（y = 2至4）物种的表面上。结果表明，在典型的实验条件下，高O2/SO2气体比，形成SO 4修饰的PdO（101）是有利的，并有助于显着的中毒PdO（101），因为它阻止了配位不饱和的Pd原子，被确定为发挥关键作用的甲烷的活化。在低温下，SO2氧化形成SO 3和SO 4物种是通过Eley-Rideal和Langmuir-Hinshelwood机制高度放热的，但受到O2解离的高活化势垒的限制。另一方面，Mars-van Krevelen机制具有较低的重复性，但提供了简单的基本步骤。从这些结果，见解的Pd基抗硫中毒甲烷氧化催化剂的设计。
PdO efficiently catalyzes the oxidation of methane but suffers tremendously from sulfur poisoning that lowers its catalytic activity. In this work, first principles calculations were performed to reveal the mechanism of PdO(101) sulfation and how the active sites for methane activation are altered upon the formation of SOy (y = 2 to 4) species on the surface. The results suggest that under typical experimental conditions with a high O2/SO2 gas ratio, the formation of SO4-decorated PdO(101) is favored and contributes significantly to the poisoning of PdO(101) as it blocks the coordinatively unsaturated Pd atoms that were identified to play a crucial role in the activation of methane. At a low temperature regime, SO2 oxidation forming SO3 and SO4 species is highly exothermic via the Eley–Rideal and Langmuir–Hinshelwood mechanisms but is limited by the high activation barrier for O2 dissociation. On the other hand, the Mars–van Krevelen mechanism has low exothermicity but provides facile elementary steps. From these results, insights into the design of PdO-based sulfur poisoning-resistant methane oxidation catalysts were drawn.