Qiu Guanghao, Pei Qijun, Yu Yang, Jing Zijun, Wang Jintao, He Teng, Chen Ping
Dalian National Laboratory for Clean Energy, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, P. R. China.
University of Chinese Academy of Sciences, Beijing, 100049, P. R. China.
Chem Asian J. 2021 Sep 20;16(18):2633-2640. doi: 10.1002/asia.202100661. Epub 2021 Aug 4.
Classical strong metal-support interaction (SMSI) is of significant importance to heterogeneous catalysis, where electronic promotion and encapsulation of noble metal by reducible support are two main intrinsic properties of SMSI. However, the excessive encapsulation will inevitably hamper the contact between active sites and reactant, leading to reduced activity in catalysis. Herein, alkaline earth metal salts are employed to depress the encapsulation of Ru nanoparticles in Ru/TiO catalyst in the present study. Thermodynamic calculation, transmission electron microscopy (TEM) and chemisorption results show that the alkaline earth metal salts could successfully prevent the migration of TiO overlayer to Ru nanoparticles in Ru/TiO catalyst via in situ formation of titanates, resulting in high exposure of active metal. Meanwhile, X-ray photoelectron spectroscopy (XPS) and hydrogen temperature-programmed reduction (H -TPR) results reveal that an even stronger electron donation from the reduced support to Ru nanoparticles is achieved. As a result, the alkaline earth metal salts-doped Ru/TiO catalysts exhibit superior activity in catalytic hydrogenation of aromatics, which is in contrast to the pristine Ru/TiO catalyst that shows negligible activity under the same conditions due to the excess encapsulation of Ru nanoparticles in Ru/TiO catalyst.
经典的强金属-载体相互作用（SMSI）对多相催化具有重要意义，其中电子促进和可还原载体对贵金属的包覆是SMSI的两个主要内在特性。然而，过度包覆不可避免地会阻碍活性位点与反应物之间的接触，导致催化活性降低。在本研究中，采用碱土金属盐抑制Ru/TiO催化剂中Ru纳米颗粒的包覆。热力学计算、透射电子显微镜（TEM）和化学吸附结果表明，碱土金属盐可通过原位形成钛酸盐成功阻止Ru/TiO催化剂中TiO覆盖层向Ru纳米颗粒的迁移，从而使活性金属高度暴露。同时，X射线光电子能谱（XPS）和氢气程序升温还原（H-TPR）结果表明，还原后的载体向Ru纳米颗粒的电子给予作用更强。结果，碱土金属盐掺杂的Ru/TiO催化剂在芳烃催化加氢中表现出优异的活性，这与原始的Ru/TiO催化剂形成对比，后者由于Ru/TiO催化剂中Ru纳米颗粒的过度包覆，在相同条件下活性可忽略不计。
