Integrated Catalysis-Surface Science-Theory Approach to Understand Selectivity in the Hydrogenation of 1-Hexyne to 1-Hexene on PdAu Single-Atom Alloy Catalysts,ACS Catalysis

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Integrated Catalysis-Surface Science-Theory Approach to Understand Selectivity in the Hydrogenation of 1-Hexyne to 1-Hexene on PdAu Single-Atom Alloy Catalysts
ACS Catalysis ( IF 11.3 ) Pub Date : 2019-08-13 00:00:00 , DOI: 10.1021/acscatal.9b00491
Jilei Liu , Matthew B. Uhlman , Matthew M. Montemore ₁ , Antonios Trimpalis , Georgios Giannakakis , Junjun Shan , Sufeng Cao , Ryan T. Hannagan , E. Charles H. Sykes , Maria Flytzani-Stephanopoulos

Affiliation

The selective hydrogenation of alkynes to alkenes is an important industrial process. However, achieving high selectivity and reducing the usage of precious platinum group metals are still challenging for the conventional hydrogenation catalysts. With atomically dispersed active metal atoms on the surface of a host metal, single-atom alloys (SAAs) have shown excellent hydrogenation selectivity and activity, but their hydrogenation mechanism is not fully understood. This work reports on the selective hydrogenation of 1-hexyne to 1-hexene on PdAu SAA catalysts. Au is a highly selective hydrogenation catalyst, but it is not active at low temperatures. Through measurements of reaction kinetics and in operando spectroscopy studies, we follow the much more facile activation of PdAu SAA catalysts and demonstrate the different hydrogenation chemistry of single Pd atoms and Pd nanoparticles (NPs). We further investigate the role of Pd atoms and the mechanism behind the improved hydrogenation selectivity through surface science and density functional theory. These studies indicate that the difference in reactivity stems from the relative energy barrier heights for over-hydrogenating the terminal C atom. The complementary catalysis-surface science-theory investigation described here is a powerful and general approach for understanding and controlling NP performance. The selective hydrogenation on PdAu SAAs is demonstrated and understood fundamentally, which serves as a guide for future designs of this type of catalyst.

中文翻译：

集成催化-表面科学-理论方法了解PdAu单原子合金催化剂上1-己烯加氢为1-己烯的选择性

炔烃的选择性加氢为烯烃是重要的工业过程。然而，对于常规氢化催化剂而言，实现高选择性并减少贵重铂族金属的使用仍然是挑战。通过原子分散在主体金属表面的活性金属原子，单原子合金（SAA）表现出出色的氢化选择性和活性，但它们的氢化机理尚未完全明了。这项工作报告了在PdAu SAA催化剂上1-己炔选择性加氢为1-己烯的过程。金是高度选择性的氢化催化剂，但在低温下不具有活性。通过反应动力学的测量和操作光谱学研究中，我们遵循了更容易激活的PdAu SAA催化剂的方法，并证明了单个Pd原子和Pd纳米颗粒（NPs）的不同氢化化学。我们通过表面科学和密度泛函理论进一步研究了Pd原子的作用以及提高氢化选择性的机理。这些研究表明，反应性的差异源于末端C原子过度氢化的相对能垒高度。此处描述的互补催化表面科学理论研究是理解和控制NP性能的有力且通用的方法。从根本上证明和理解了PdAu SAA上的选择性加氢，这为将来设计此类催化剂提供了指导。

更新日期：2019-08-13

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