S、SO和SO在Pt(001)、(011)和(111)表面的行为：一项密度泛函理论研究。
Behavior of S, SO, and SO on Pt (001), (011), and (111) surfaces: A DFT study.
作者信息
Ungerer Marietjie J, van Sittert Cornelia G C E, de Leeuw Nora H
机构信息
Laboratory for Applied Molecular Modelling, Research Focus Area: Chemical Resource Beneficiation, North-West University, Private Bag X6001, Potchefstroom 2520, South Africa.
School of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, United Kingdom.
出版信息
J Chem Phys. 2021 May 21;154(19):194701. doi: 10.1063/5.0043501.
In the hybrid sulfur (HyS) cycle, the reaction between SO and HO is manipulated to produce hydrogen with water and sulfuric acid as by-products. However, sulfur poisoning of the catalyst has been widely reported to occur in this cycle, which is due to strong chemisorption of sulfur on the metal surface. The catalysts may deactivate as a result of these impurities present in the reactants or incorporated in the catalyst during its preparation and operation of the HyS cycle. Here, we report a density functional theory investigation of the interaction between S, SO, and SO with the Pt (001), (011), and (111) surfaces. First, we have investigated the adsorption of single gas phase molecules on the three Pt surfaces. During adsorption, the 4F hollow sites on the (001) and (011) surfaces and the fcc hollow site on the (111) surface were preferred. S adsorption followed the trend of (001) > (011) > (111), while SO adsorption showed (001) > (011) > (111) and SO adsorption was most stable in a S,O,O bound configuration on the (001) > (011) > (111) sites. The surface coverage was increased on all the surfaces until a monolayer was obtained. The highest surface coverage for S shows the trend (001) = (111) > (011), and for SO it is (001) > (011) > (111), similar to SO where we found (001) > (011) > (111). These trends indicate that the (001) surface is more susceptible to S species poisoning. It is also evident that both the (001) and (111) surfaces were reactive toward S, leading to the formation of S. The high coverage of SO showed the formation of SO and SO, especially on the (011) surface. The thermodynamics indicated that an increased temperature of up to 2000 K resulted in Pt surfaces fully covered with elemental S. The SO coverage showed θ ≥ 1.00 on both the (001) and (011) surfaces and θ = 0.78 for the (111) surface in the experimental region where the HyS cycle is operated. Lower coverages of SO were observed due to the size of the molecule.
在混合硫（HyS）循环中，通过控制SO与HO之间的反应来生产氢气，同时产生水和硫酸作为副产物。然而，在该循环中催化剂的硫中毒现象已被广泛报道，这是由于硫在金属表面的强烈化学吸附所致。在HyS循环的反应物中存在的这些杂质，或在催化剂制备及运行过程中掺入催化剂的杂质，可能会导致催化剂失活。在此，我们报告了一项关于S、SO和SO与Pt（001）、（011）和（111）表面相互作用的密度泛函理论研究。首先，我们研究了单个气相分子在这三个Pt表面上的吸附情况。在吸附过程中，（001）和（011）表面上的4F空心位以及（111）表面上的fcc空心位是优先吸附位点。S的吸附遵循（001）>（011）>（111）的趋势，而SO的吸附表现为（001）>（011）>（111），并且SO在（001）>（011）>（111）位点上以S,O,O键合构型吸附时最为稳定。所有表面上的表面覆盖率都不断增加，直至形成单分子层。S的最高表面覆盖率呈现出（001） =（111）>（011）的趋势，对于SO而言是（001）>（011）>（111），与SO的情况类似，我们发现其为（001）>（011）>（111）。这些趋势表明（001）表面更容易受到S物种中毒的影响。同样明显的是，（001）和（111）表面对S都具有反应活性，会导致S的形成。SO的高覆盖率表明会形成SO和SO，尤其是在（011）表面上。热力学表明，温度升高至2000 K会使Pt表面完全被元素S覆盖。在HyS循环运行的实验区域中，（001）和（011）表面上SO的覆盖率显示θ≥1.00，而（111）表面的θ = 0.78。由于分子尺寸的原因，观察到SO的覆盖率较低。
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