Paul Scherrer Institut, 5232, Villigen PSI, Switzerland.
Institute of Chemical Sciences and Engineering, École polytechnique fédérale de Lausanne (EFPL), 1015, Lausanne, Switzerland.
ChemSusChem. 2017 Jun 9;10(11):2505-2517. doi: 10.1002/cssc.201700358. Epub 2017 May 11.
Perovskite-type oxides have shown the ability to reversibly segregate precious metals from their structure. This reversible segregation behavior was explored for a commonly used catalyst metal, Ni, to prevent Ni sintering, which is observed on most catalyst support materials. Temperature-programmed reduction, X-ray diffraction, X-ray absorption spectroscopy, electron microscopy, and catalytic activity tests were used to follow the extent of reversible Ni segregation. LaFe Ni O (0≤x≤0.2) was synthesized using a citrate-based solution process. After reduction at 600 °C, metallic Ni particles were displayed on the perovskite surfaces, which were active towards the hydrogenation of CO . The overall Ni reducibility was proportional to the Ni content and increased from 35 % for x=0.05 to 50 % for x=0.2. Furthermore, Ni could be reincorporated reversibly into the perovskite lattice during reoxidation at 650 °C. This could be exploited for catalyst regeneration under conditions under which impregnated materials such as Ni/LaFeO and Ni/Al O suffer from sintering.
钙钛矿型氧化物具有将贵金属从其结构中可逆分离的能力。这种可逆的分离行为是针对一种常用的催化剂金属 Ni 进行探索的，以防止 Ni 在大多数催化剂载体材料上观察到的烧结。采用程序升温还原、X 射线衍射、X 射线吸收光谱、电子显微镜和催化活性测试来跟踪可逆 Ni 分离的程度。使用基于柠檬酸盐的溶液法合成 LaFeNiO（0≤x≤0.2）。在 600°C 还原后，金属 Ni 颗粒显示在钙钛矿表面，对 CO 的氢化具有活性。整体 Ni 可还原性与 Ni 含量成正比，并从 x=0.05 时的 35%增加到 x=0.2 时的 50%。此外，Ni 可以在 650°C 下重新氧化时可逆地重新掺入钙钛矿晶格中。这可以用于在浸渍材料（如 Ni/LaFeO 和 Ni/Al2O3）会发生烧结的条件下进行催化剂再生。
