Reactivity of Pd–MO 2 encapsulated catalytic systems for CO oxidation
Reactivity of Pd–MO 2 encapsulated catalytic systems for CO oxidation
复制标题
Pd-MO 2 封装催化体系对 CO 氧化的反应活性
DOI：
10.1039/d1cy01916c
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发表时间：
2022
影响因子：
5
通讯作者：
Medlin, J. Will
中科院分区：
文献类型：
--
作者：
Paz Herrera, Laura;Freitas de Lima e Freitas, Lucas;Hong, Jiyun;Hoffman, Adam S.;Bare, Simon R.;Nikolla, Eranda;Medlin, J. Will
在这项研究中，我们提出了一项调查，旨在表征和理解封装的催化结构之间的金属核心（即，Pd）和氧化物壳（即，TiO 2、ZrO 2和CeO 2）。封装的催化剂合成使用两个步骤的程序，涉及初始的胶体合成的Pd纳米粒子（NP）的各种配体和随后的溶胶-凝胶封装的NP与多孔MO 2（M = Ti，Zr，Ce）壳封端。由于Pd-MO 2界面处独特的物理化学性质，封装的催化体系显示出比Pd/MO 2支撑结构更高的活性。Pd@ZrO2对CO氧化具有最高的催化活性。结果还表明，在低温下，由非晶ZrO 2壳结构封装的Pd中的活性位点比结晶氧化物封装的结构的活性显著更高。此外，CO DRIFTS研究表明，Pd再分散发生在CO氧化反应条件下，并作为氧化物壳组合物的函数，仅在Pd @ TiO 2系统中观察到，反应后可能形成较小的NP和氧化物负载的Pd簇。该研究表明，金属氧化物组合物和（在某些情况下）结晶度在包封催化体系的催化剂活性中起主要作用。
In this study, we present an investigation aimed at characterizing and understanding the synergistic interactions in encapsulated catalytic structures between the metal core (i.e., Pd) and oxide shell (i.e., TiO2, ZrO2, and CeO2). Encapsulated catalysts were synthesized using a two-step procedure involving the initial colloidal synthesis of Pd nanoparticles (NPs) capped by various ligands and subsequent sol–gel encapsulation of the NPs with porous MO2 (M = Ti, Zr, Ce) shells. The encapsulated catalytic systems displayed higher activity than the Pd/MO2 supported structures due to unique physicochemical properties at the Pd–MO2 interface. Pd@ZrO2 exhibited the highest catalytic activity for CO oxidation. Results also suggested that the active sites in Pd encapsulated by an amorphous ZrO2 shell structure were significantly more active than the crystalline oxide encapsulated structures at low temperatures. Furthermore, CO DRIFTS studies showed that Pd redispersion occurred under CO oxidation reaction conditions and as a function of the oxide shell composition, being observed in Pd@TiO2 systems only, with potential formation of smaller NPs and oxide-supported Pd clusters after reaction. This investigation demonstrated that metal oxide composition and (in some cases) crystallinity play major roles in catalyst activity for encapsulated catalytic systems.