期刊
CATALYSTS
卷 13, 期 2, 页码 -出版社
MDPI
DOI: 10.3390/catal13020405
关键词
cobalt catalyst; ammonia synthesis; neodymium oxide; support; hydrogen poisoning
A series of neodymium oxide-supported cobalt catalysts with different cobalt content were prepared. The effect of cobalt content on the structure, morphology, crystal structure, surface state, composition and activity of the catalysts was investigated. The results show that the catalyst activity strongly depends on the cobalt content due to the changes in cobalt particle size. The productivity per catalyst mass increases with cobalt content, while TOF remains constant.
A series of neodymium oxide-supported cobalt catalysts with cobalt content ranging from 10 to 50 wt.% was obtained through the recurrent deposition-precipitation method. The effect of active phase, i.e., metallic cobalt, content on structural parameters, morphology, crystal structure, surface state, composition and activity of the catalysts was determined after detailed physicochemical measurements were performed using ICP-AES, N-2 physisorption, XRPD, TEM, HRTEM, STEM-EDX, H-2-TPD and XPS methods. The results indicate that the catalyst activity strongly depends on the active phase content due to the changes in average cobalt particle size. With the increase of the cobalt content, the productivity per catalyst mass increases, while TOF maintains a constant value. The TOF is below average only for the catalyst with the lowest cobalt content, i.e., when the average Co particle size is below 20 nm. This is due to the predominance of strong hydrogen binding sites on the surface, leading to hydrogen poisoning which prevents nitrogen adsorption, thus inhibiting the rate-determining step of the process.
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