New efficient catalyst for ammonia synthesis: barium-promoted cobalt on carbon

Hagen, Stefan; Barfod, Rasmus; Fehrmann, Rasmus; Jacobsen, Claus J. H.; Teunissen, Herman T.; Ståhl, Kenny; Chorkendorff, Ib

doi:10.1039/b202781j

Cited by 83 publications

(108 citation statements)

References 13 publications

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“…This result is similar to other studies of ammonia synthesis kinetics on different catalysts [2,3,21]. The apparent activation energy is 83 kJ mol −1 at a pressure of 3.0 MPa, which is similar to the result obtained on Ru/MgO and Cs 2 CO 3 -Ru/MgO and lower than that on CsNO 3 -Ru/MgO and Ru-Ba/AC catalysts [2,24].…”

Section: Resultssupporting

confidence: 81%

“…There are three considerations on this problem in the literature, i.e. metal sintering, loss of the active component and methanation of the support, of which the last becomes obvious when the catalyst has been operated under working conditions for a long time [2][3][4][5][6]. Therefore, a more stable support is required, and this has led to a search for an alternative to active carbon.…”

Section: Introductionmentioning

confidence: 99%

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Ammonia synthesis on graphitic-nanofilament supported Ru catalysts

Liang

Feng

et al. 2004

Journal of Molecular Catalysis A: Chemical

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Section: Resultssupporting

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Ammonia synthesis on graphitic-nanofilament supported Ru catalysts

Liang

Feng

et al. 2004

Journal of Molecular Catalysis A: Chemical

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“…Cobalt-based systems seem to fulfill these conditions. At first, cobalt was used as an effective addition to the fused iron catalyst [16,17], or in Fe/C-type systems [15,18]. Furthermore, triple nitrides containing cobalt and promoted with cesium proved to be active ammonia synthesis catalysts [19,20].…”

Section: Introductionmentioning

confidence: 99%

“…The promoted Ru/activated carbon systems proved to be significantly more active [5][6][7][8][9][10] than the fused iron commonly used in the industry. Although various supported ruthenium catalysts have been shown to be very active too [11][12][13][14], there is still doubt [15] whether the high cost of the active metal (Ru) is counterbalanced by its advantageous catalytic properties. Therefore, efforts have been made to obtain a new system, which would be more effective than the iron-based ones, especially at high conversions and simultaneously, would be considerably cheaper than those based on ruthenium.…”

Section: Introductionmentioning

confidence: 99%

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

et al. 2011

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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 H 2 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 NH 3 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% NH 3 ), 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.

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“…The catalytic NH 3 synthesis is very attractive as a model reaction in the fundamental studies, too [2]. For the above reasons, the researchers from industrial centres and academia are still active in the field of NH 3 synthesis and they try to work out a completely new catalyst [1,[3][4][5][6][7][8][9][10] or to improve the formula and properties of the conventional iron one [11][12][13][14][15]. Among several new catalytic systems investigated in the last 30 years, only ruthenium supported on high surface area graphite (HSAG) was implemented to the industrial practice so far.…”

Section: Introductionmentioning

confidence: 99%

Ammonia synthesis over the Ba-promoted ruthenium catalysts supported on boron nitride

et al. 2005

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Barium promoted ruthenium catalysts deposited on the boron nitride supports were characterised (XRD, O 2 and CO chemisorption) and tested in NH 3 synthesis. Prior to use, the raw BN materials marked as BNS (Starck, 96 m 2 /g) and HCV (Advanced Ceramics Corporation Cleveland USA, 40 m 2 /g) were heated in an ammonia stream at 700-800°C for 120 h. As a result, the oxygen content was reduced from 7.0 at% (BNS) to 3.5 at% (BNS NH3 ) and from 3.8 to 2.7 at% (HCV NH3 ), as evidenced by XPS. The kinetic studies of NH 3 synthesis (63 or 90 bar; H 2 :N 2 = 3:1) revealed that the catalysts based on the modified supports were more active, respectively, than those derived from starting nitrides, the difference being especially pronounced in the case of BNS and BNS NH3 . Studies of the catalysts activation have shown, in turn, that the stabilisation in a H 2 :N 2 = 3:1 mixture at 1 bar is very slow, i.e. the reaction rate increases slowly versus time on stream even at a high temperature of 550 -600°C. Stabilisation is faster and the NH 3 synthesis rates are higher when the activation is performed with an ammonia rich mixture (10% NH 3 in H 2 :N 2 = 3:1) flowing under high pressure of 90 bar. It is suggested that boron oxide (an impurity) acts as a deactivating agent for Ba-Ru/BN and that the reaction between NH 3 and B 2 O 3 (B 2 O 3 + 2NH 3 = 2BN + 3H 2 O) is responsible for the activity increase. A poisoning mechanism of B 2 O 3 is discussed.

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New efficient catalyst for ammonia synthesis: barium-promoted cobalt on carbon

Abstract: Barium-promoted cobalt catalysts supported on carbon exhibit higher ammonia activities at synthesis temperatures than the commercial, multipromoted iron catalyst and also a lower ammonia inhibition.

Cited by 83 publications

References 13 publications

Ammonia synthesis on graphitic-nanofilament supported Ru catalysts

Ammonia synthesis on graphitic-nanofilament supported Ru catalysts

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

Ammonia synthesis over the Ba-promoted ruthenium catalysts supported on boron nitride

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