当前位置：
X-MOL 学术
›
ACS Catal.
›
论文详情
Our official English website, www.x-mol.net, welcomes your
feedback! (Note: you will need to create a separate account there.)
Coking-Resistant Sub-Nano Dehydrogenation Catalysts: PtnSnx/SiO2 (n = 4, 7)
ACS Catalysis ( IF 11.3 ) Pub Date : 2020-03-17 , DOI: 10.1021/acscatal.0c00668 Timothy J. Gorey 1 , Borna Zandkarimi 2 , Guangjing Li 1 , Eric T. Baxter 1 , Anastassia N. Alexandrova 2, 3 , Scott L. Anderson 1
ACS Catalysis ( IF 11.3 ) Pub Date : 2020-03-17 , DOI: 10.1021/acscatal.0c00668 Timothy J. Gorey 1 , Borna Zandkarimi 2 , Guangjing Li 1 , Eric T. Baxter 1 , Anastassia N. Alexandrova 2, 3 , Scott L. Anderson 1
Affiliation
|
We present a combined experimental/theoretical study of Ptn/SiO2 and PtnSnx/SiO2 (n = 4, 7) model catalysts for the endothermic dehydrogenation of hydrocarbons, using the ethylene intermediate as a model reactant. Mass-selected Ptn clusters were deposited onto amorphous SiO2/Si(100) to make the PtnSiO2 model catalysts. To produce PtnSnx clusters, size-selected Ptn was used to seed selective deposition of Sn on Pt via a self-limiting H2/SnCl4/H2 reaction sequence. Model catalysts were analyzed using C2D4 and CO temperature-programmed desorption (TPD), low-energy ion scattering (ISS), X-ray photoelectron spectroscopy (XPS), plane wave density functional theory (DFT) global optimization combined with a statistical mechanical description of the catalytic interface, and a DFT mechanistic study. Supported pure Ptn clusters are found to be highly active toward dehydrogenation of C2D4, quickly deactivating due to a combination of carbon deposition and sintering, resulting in loss of accessible Pt sites. Addition of Sn to Ptn clusters results in the complete suppression of C2D4 dehydrogenation and carbon deposition and also stabilizes the clusters against thermal sintering. Theory shows that both systems have thermal access to a multitude of cluster structures and adsorbate configurations that form a statistical ensemble. While Pt4/SiO2 clusters bind ethylene in both di-σ- and π-bonded configurations, Pt4Sn3/SiO2 binds C2H4 only in the π mode, with di-σ bonding suppressed by a combination of electronic and geometric features of the PtSn clusters. Dehydrogenation reaction profiles on the accessible cluster isomers were calculated using the climbing image nudged elastic band (CI-NEB) method. Dehydrogenation of di-σ-bound ethylene is computed to dominate and is suppressed by Sn addition, in agreement with the experiments. DFT indicates that, after Sn alloying, the barrier for ethane-to-ethylene conversion is lower than that for unwanted ethylene dehydrogenation.
中文翻译：
耐焦化的亚纳米脱氢催化剂：Pt n Sn x / SiO 2（n = 4，7）
我们提出了使用乙烯中间体作为模型反应物的Pt n / SiO 2和Pt n Sn x / SiO 2（n = 4，7）模型催化剂用于烃类吸热脱氢的组合实验/理论研究。将大量选择的Pt n团簇沉积到非晶SiO 2 / Si（100）上，制成Pt n SiO 2模型催化剂。为了产生Pt n Sn x团簇，使用尺寸选择的Pt n通过自限H 2 / SnCl 4 / H种子在Pt上选择性沉积Sn2反应顺序。使用C 2 D 4和CO程序升温脱附（TPD），低能离子散射（ISS），X射线光电子能谱（XPS），平面波密度泛函理论（DFT）全局优化结合A催化界面的统计力学描述，以及DFT机理研究。发现支持的纯Pt n簇对C 2 D 4的脱氢具有很高的活性，由于碳沉积和烧结的结合而迅速失活，从而导致可访问的Pt部位的损失。将Sn添加到Pt n簇中可完全抑制C 2 D 4脱氢和碳沉积，还可以稳定团簇，防止热烧结。理论表明，两个系统都可以热访问形成统计集合的大量簇结构和吸附物构型。尽管Pt 4 / SiO 2簇以双σ键和π键结构结合乙烯，但Pt 4 Sn 3 / SiO 2结合C 2 H 4仅在π模式下，通过结合PtSn簇的电子和几何特征来抑制di-σ键。使用爬升图像微调弹性带（CI-NEB）方法计算可及的簇异构体上的脱氢反应曲线。与实验一致，计算出二σ-键合乙烯的脱氢占主导地位，并通过添加锡来抑制脱氢。DFT表明，在锡合金化之后，乙烷到乙烯转化的屏障比不需要的乙烯脱氢的屏障低。
更新日期：2020-04-23
中文翻译：
耐焦化的亚纳米脱氢催化剂：Pt n Sn x / SiO 2（n = 4，7）
我们提出了使用乙烯中间体作为模型反应物的Pt n / SiO 2和Pt n Sn x / SiO 2（n = 4，7）模型催化剂用于烃类吸热脱氢的组合实验/理论研究。将大量选择的Pt n团簇沉积到非晶SiO 2 / Si（100）上，制成Pt n SiO 2模型催化剂。为了产生Pt n Sn x团簇，使用尺寸选择的Pt n通过自限H 2 / SnCl 4 / H种子在Pt上选择性沉积Sn2反应顺序。使用C 2 D 4和CO程序升温脱附（TPD），低能离子散射（ISS），X射线光电子能谱（XPS），平面波密度泛函理论（DFT）全局优化结合A催化界面的统计力学描述，以及DFT机理研究。发现支持的纯Pt n簇对C 2 D 4的脱氢具有很高的活性，由于碳沉积和烧结的结合而迅速失活，从而导致可访问的Pt部位的损失。将Sn添加到Pt n簇中可完全抑制C 2 D 4脱氢和碳沉积，还可以稳定团簇，防止热烧结。理论表明，两个系统都可以热访问形成统计集合的大量簇结构和吸附物构型。尽管Pt 4 / SiO 2簇以双σ键和π键结构结合乙烯，但Pt 4 Sn 3 / SiO 2结合C 2 H 4仅在π模式下，通过结合PtSn簇的电子和几何特征来抑制di-σ键。使用爬升图像微调弹性带（CI-NEB）方法计算可及的簇异构体上的脱氢反应曲线。与实验一致，计算出二σ-键合乙烯的脱氢占主导地位，并通过添加锡来抑制脱氢。DFT表明，在锡合金化之后，乙烷到乙烯转化的屏障比不需要的乙烯脱氢的屏障低。
京公网安备 11010802027423号