Principle on Selecting the Coordination Ligands of Palladium Precursors Encapsulated by Zeolite for an Efficient Purification of Formaldehyde at Ambient Temperature.
Principle on Selecting the Coordination Ligands of Palladium Precursors Encapsulated by Zeolite for an Efficient Purification of Formaldehyde at Ambient Temperature.
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DOI：
10.1021/acs.est.3c05190
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发表时间：
2023-09
影响因子：
11.4
通讯作者：
Zhaoying Di;Runduo Zhang;Xiaonan Guo;Hanxiao Shen;Yaping Li;Jingbo Jia;Yingxi Wei
中科院分区：
文献类型：
--
作者：
Zhaoying Di;Runduo Zhang;Xiaonan Guo;Hanxiao Shen;Yaping Li;Jingbo Jia;Yingxi Wei
高性能沸石负载贵金属催化剂具有低负载量、高活性组分分散性等优点，是实现甲醛(HCHO)室温完全氧化的最有前景的材料。本工作采用一锅法制备了不同尺寸的钯纳米粒子(Pd NPs)，并利用不同的稳定配体，成功地将不同大小的Pd纳米粒子包裹到了Silicalite-1(S-1)沸石骨架中。阐明了钯配位配体的选择原则：理想配位配体具有N原子多、碳链短、支链小、双齿配位等特点。因此，性能最好的0.2Pd@S-1(乙二胺)催化剂对甲醛的氧化表现出优异的性能，即使在室温下也能实现100%的转化率。高分辨率高角度环状暗场扫描电子显微镜(HR HAADF-STEM)和密度泛函理论(DFT)计算表明，该络合物是由Pd~(2+)与乙二胺络合形成的，在沸石合成的同时显示出最小的空间位电阻，导致焙烧后Pd主要位于S-1的5元环(5-MR)通道内，从而限制了Pd团簇的生长，促进了Pd团簇的分散。
High-performance zeolite-supported noble metal catalysts with low loading and high dispersion of active components are the most promising materials for achieving the complete oxidation of formaldehyde (HCHO) at room temperature. In this work, palladium nanoparticles (Pd NPs) with different sizes were successfully encapsulated inside the silicalite-1 (S-1) zeolite framework by using diverse stabling ligands via the one-pot method. Thereafter, the rule on selecting the coordinative ligands for palladium was clarified: more N atoms, a short carbon chain, a smaller branch chain, and bidentate coordination are characteristics of an ideal ligand. Accordingly, the best-performing 0.2Pd@S-1(Ethylenediamine) catalyst exhibited outstanding performance for HCHO oxidation, achieving 100% conversion even at room temperature. High-resolution high-angle annular dark-field scanning transmission electron microscopy (HR HAADF-STEM) and density functional theory (DFT) calculations indicate that the chelate is formed by complexation of Pd2+ ions with ethylenediamine, displaying the smallest spatial site resistance simultaneously with the zeolite synthesis, resulting in Pd located mostly within the 5-membered ring (5-MR) channels of S-1 after calcination, thus limiting the growth of Pd clusters and promoting their dispersion.