Enhanced Stability of Pd/ZnO Catalyst for CO Oxidative Coupling to Dimethyl Oxalate: Effect of Mg2+ Doping

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• 作者：Si-Yan Peng ; Zhong-Ning Xu ; Qing-Song Chen ; Zhi-Qiao Wang ; Dong-Mei Lv ; Jing Sun ; Yumin Chen ; Guo-Cong Guo
• 刊名：ACS Catalysis
• 出版年：2015
• 出版时间：July 2, 2015
• 年：2015
• 卷：5
• 期：7
• 页码：4410-4417
• 全文大小：530K
• ISSN：2155-5435

文摘

The catalytic performances of supported Pd nanoparticles (NPs) are strongly dependent on the support materials for CO oxidative coupling to dimethyl oxalate (DMO). Herein, hierarchical flower-like ZnO microspheres composed of porous nanosheets are employed as a new support material for a Pd catalyst, which exhibits excellent catalytic activity for CO oxidative coupling to DMO. The conversion of CO and the selectivity to DMO reach up to 67% and 98% at 130 掳C, respectively. Unfortunately, the high activity of Pd/ZnO catalyst gradually deteriorates within 100 h. To resolve the poor stability, we further introduce Mg²⁺ ions into the ZnO support. It is exciting that the catalytic activity of the Mg²⁺-doped-ZnO-supported Pd nanocatalyst (Pd/Mg鈥揨nO) can be maintained for at least 100 h without obvious decay. Catalytic stability is greatly improved by the doping of Mg²⁺ ions. XRD, UV鈥搗isible diffuse reflectance spectra, and high-angle annular dark field scanning transmission electron microscopy characterizations demonstrate that a small portion of Mg²⁺ ions are successfully incorporated into the lattice of the ZnO support to form a Zn鈥揗g oxide solid solution. XPS, in situ diffuse reflectance Fourier transform infrared spectroscopy, and H₂-temperature-programmed reduction results reveal that the introduction of Mg²⁺ ions into the ZnO support leads to a strong metal鈥搒upport interaction caused by electron transfer from the ZnO substrate to the Pd NPs, which can effectively restrain the sintering of the active Pd NPs; retard the growth of Pd NPs; and thus, enhance the catalytic stability.