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Promoting Effects of Lanthan on Ru/AC for Ammonia Synthesis: Tuning Catalytic Efficiency and Stability Simultaneously
Author(s) -
Ni Jun,
Lin Jingdong,
Wang Xiuyun,
Lin Bingyu,
Lin Jianxin,
Jiang Lilong
Publication year - 2017
Publication title -
chemistryselect
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.437
H-Index - 34
ISSN - 2365-6549
DOI - 10.1002/slct.201700859
Subject(s) - methanation , catalysis , chemisorption , ruthenium , thermal stability , carbon monoxide , ammonia production , adsorption , inorganic chemistry , hydrogen , chemistry , ammonia , desorption , particle size , temperature programmed reduction , syngas , organic chemistry
La−Ba‐K−Ru/AC catalysts for ammonia synthesis were prepared by co‐impregnation method using graphited active‐carbon as the support and water‐soluble chloride‐free Ru complex as the precursor. The results demonstrate that the La promoted Ba‐K−Ru/AC catalysts exhibit good catalytic activity, high thermal stability and strong resistance against methanation. TEM (Transmission Electron Microscope) and CO (carbon monoxide) chemisorption analysis indicate that the Ru particles had a relatively uniform size of 3∼5 nm and the particle surface might be partially covered by LaOx and BaOx. H 2 ‐TPR (Temperature Programmed Reduction) results suggest that strong interactions might exist between the Ru particles and the promoters (La and Ba). The N 2 ‐TPD (Temperature Programmed Desorption) and H 2 ‐TPD measurements show that the presence of small amount of La enhances the adsorption of N 2 and inhibits the adsorption of H 2 , resulting in higher TOF values and better catalytic performances. Moreover, no obvious agglomeration of Ru particles was observed on the catalysts after heat resistance. The superior catalytic stability of La−Ba‐K−Ru/AC is associated with its strong resistance against methanation of active‐carbon due to highly coverage of ruthenium surface and strong inhibition of hydrogen by promoters.