A series of MgAl-layered double oxides（LDO） doped with different rare-earth elements（Y, La, and Ce）were synthesized by the calcination of Mg-Al layered double hydroxides, and Ru, which were used to prepare ammonia...A series of MgAl-layered double oxides（LDO） doped with different rare-earth elements（Y, La, and Ce）were synthesized by the calcination of Mg-Al layered double hydroxides, and Ru, which were used to prepare ammonia synthesis catalysts. The as-obtained oxides and catalysts were characterized by XRD,TEM, TPD, TPR and XPS to understand their catalytic performances in ammonia synthesis. The H_2-TPR and HRTEM studies reveal that Ru/Y-LDO catalyst possesses more active Ru metal and small particle size.The XPS demonstrates that the electronic interaction between Y and Ru metals is stronger, which can be tentatively explained by most of Y inserted into the hydrotalcites structure. CO_2-TPD demonstrates that Ru/Y-LDO catalyst shows stronger basic site densities than catalysts doped with Ce and La. Higher activity of the Ru/Y-LDO catalyst can be attributed to smaller particle size, more active metal（Ru） and strong Ru-support interaction.展开更多
基金Project supported by the Natural Science Foundation of Fujian Province(2014J01043)the National Natural Science Foundation of China(21203028)PetroChina Innovation Foundation(2016D-5007-0504)
文摘A series of MgAl-layered double oxides（LDO） doped with different rare-earth elements（Y, La, and Ce）were synthesized by the calcination of Mg-Al layered double hydroxides, and Ru, which were used to prepare ammonia synthesis catalysts. The as-obtained oxides and catalysts were characterized by XRD,TEM, TPD, TPR and XPS to understand their catalytic performances in ammonia synthesis. The H_2-TPR and HRTEM studies reveal that Ru/Y-LDO catalyst possesses more active Ru metal and small particle size.The XPS demonstrates that the electronic interaction between Y and Ru metals is stronger, which can be tentatively explained by most of Y inserted into the hydrotalcites structure. CO_2-TPD demonstrates that Ru/Y-LDO catalyst shows stronger basic site densities than catalysts doped with Ce and La. Higher activity of the Ru/Y-LDO catalyst can be attributed to smaller particle size, more active metal（Ru） and strong Ru-support interaction.
