Praseodymium hydroxide/gold-supported precursor: a new strategy for preparing stable and active catalyst for the water-gas shift reaction,Catalysis Science & Technology

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Praseodymium hydroxide/gold-supported precursor: a new strategy for preparing stable and active catalyst for the water-gas shift reaction
Catalysis Science & Technology ( IF 4.4 ) Pub Date : 2020-08-28 , DOI: 10.1039/d0cy01263g
Junjie Shi _{1,

2,

3,

4,

5} , Hailian Li _{1,

2,

3,

4,

5} , Weixuan Zhao _{1,

2,

3,

4,

5} , Pengfei Qi _{6,

7,

8,

9,

10} , Hongxin Wang _{1,

2,

3,

4,

5}

Affiliation

Praseodymium oxide with a mixed-valence state (Pr⁴⁺/Pr³⁺) has the highest O mobility among the rare earth oxides (REOs) and holds great promise in the field of heterogeneous catalysis. Herein, a rod-shaped praseodymium hydroxide (Pr(OH)_x) support was obtained via hydrothermal method and used for the immobilization of Au nano-species by a modified deposition–precipitation (MDP) method. The resulting Au/Pr(OH)_{x_}M catalyst was tested for water-gas shift reaction (WGSR) and CO oxidation and exhibited high activity and stability in both reactions with a TOF of 0.55 s⁻¹ for WGSR, which is high compared with the reported ceria-support Au catalysts. HAADF-STEM measurements combined with the elemental composition distribution maps verified Au sub-nanospecies formed on the surface. The EXAFS and XPS studies demonstrated the transformation of the chemical state of Au from ionic Au (Au³⁺) to metallic Au (Au⁰) after the WGSR. The photoemission spectra of Pr 3d and O 1s indicate high number of O vacancies on Au/Pr(OH)_{x_}M, which facilitate the H₂O dissociation and contribute to the improved WGSR. This study shows that praseodymium hydroxide, as a hydroxyl- and O vacancy-rich support can promote the dispersion and stabilization of Au species, thus providing useful concepts for the design and preparation of active and stable catalysts for heterogeneous catalysis.

中文翻译：

氢氧化/金负载前体：制备稳定，活性的水煤气变换反应催化剂的新策略

混合价态的^P（Pr ⁴⁺ / Pr ³⁺）在稀土氧化物（REO）中具有最高的O迁移率，在多相催化领域具有广阔的前景。本文中，通过水热法获得了棒状氢氧化ase（Pr（OH）_x）载体，并通过改进的沉积沉淀（MDP）方法将其用于固定Au纳米物种。测试了所得的Au / Pr（OH）_{x _} M催化剂的水煤气变换反应（WGSR）和CO氧化，并且在两个反应中均显示出高活性和稳定性，TOF为0.55 s ^-1WGSR的催化剂，与报道的二氧化铈载体Au催化剂相比，它的含量较高。HAADF-STEM测量与元素组成分布图相结合，验证了在表面上形成的金亚纳米物种。EXAFS和XPS研究表明，WGSR之后，Au的化学态从离子Au（Au ³⁺）转变为金属Au（Au ⁰）。Pr 3d和O 1s的光发射光谱表明在Au / Pr（OH）_{x _} M上有大量的O空位，这有利于H ₂O分离并有助于改进WGSR。这项研究表明，氢氧化作为一种富含羟基和O的空位载体，可以促进Au物种的分散和稳定，从而为设计和制备用于多相催化的活性和稳定催化剂提供了有用的概念。

更新日期：2020-09-16

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