Cobalt Catalyst Doped with Cerium and Barium Obtained by Co-Precipitation Method for Ammonia Synthesis Process

Wioletta Raróg-Pilecka , Magdalena Karolewska , Elżbieta Truszkiewicz , Ewa Iwanek , Bogusław Mierzwa

Abstract

Abstract Unsupported cobalt catalysts promoted with barium (symbol Co/Ba), cerium (Co/Ce) or both (Co/Ce/Ba) were synthesized and tested in ammonia synthesis at 6.3 MPa. The Ba-free Co and Co/Ce oxide forms of the catalysts were prepared by precipitation/co-precipitation and a subsequent calcination at 500 °C. The Co and Co/Ce powders were impregnated with an aqueous solution of barium nitrite. Nitrogen physisorption and H2 chemisorption measurements revealed that cerium and barium play the role of structural promoters, which hinder the sintering of cobalt oxide during calcination and stabilize the surface of cobalt under reduction conditions. It seems that barium also modifies the surface of the active phase, i.e., cobalt. The kinetic studies of NH3 synthesis have shown that the co-promoted material (Co/Ce/Ba) is about 2–3 times more active than the system doped with barium (Co/Ba) and more than ten times as active as that with Ce. At 400 °C and at low conversion (1\% NH3), the ammonia synthesis rate (TOF) over Co/Ce/Ba proved to be almost 60\% as high as that obtained for the commercial iron catalyst (KMI, H. Topsøe) commonly used in ammonia plants all over the world. Moreover, at the same temperature and a high ammonia concentration (8\%) the co-promoted cobalt catalyst is over two times more active than the fused iron catalyst. Another asset of the cobalt catalyst is its high thermal stability. Graphical Abstract TG/DTG-MS studies of the cobalt catalysts. DTG curves of samples
Author Wioletta Raróg-Pilecka (FC / DITC)
Wioletta Raróg-Pilecka,,
- Department Of Inorganic Technology And Ceramics
, Magdalena Karolewska - [Politechnika Warszawska]
Magdalena Karolewska,,
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, Elżbieta Truszkiewicz (FC / DITC)
Elżbieta Truszkiewicz,,
- Department Of Inorganic Technology And Ceramics
, Ewa Iwanek - [Warsaw University of Technology (PW), MNiSW [80]]
Ewa Iwanek,,
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- Politechnika Warszawska
, Bogusław Mierzwa - [Institute of Physical Chemistry of the Polish Academy of Sciences]
Bogusław Mierzwa,,
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Journal seriesCatalysis Letters, ISSN 1011-372X, 1572-879X, (0 pkt)
Issue year2011
Vol141
No5
Pages678-684
Keywords in EnglishAmmonia synthesis, Barium and cerium promoters, Catalysis, Cobalt catalyst, Co-precipitation method, Industrial Chemistry/Chemical Engineering, Organometallic Chemistry, Physical Chemistry
DOIDOI:10.1007/s10562-011-0564-8
URL http://link.springer.com/article/10.1007/s10562-011-0564-8
Score (nominal)0
Score sourcejournalList
Publication indicators WoS Citations = 16; Scopus Citations = 15
Citation count*6 (2016-05-12)
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* presented citation count is obtained through Internet information analysis and it is close to the number calculated by the Publish or Perish system.
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