Abstract
The catalytic activities of three supported, barium-promoted ruthenium catalysts for ammonia synthesis are reported. The three supports are silicon nitride (Si3N4), magnesium aluminum spinel (MgAl2O4), and graphitized carbon (C). The effect of the promoter on the activity is strongly dependent on the choice of support material in accordance with several previous observations. Here, this dependence is ascribed to a difference in the affinity of the promoter for the different supports. It is shown how it is possible to image the barium promoter present on the surface of ruthenium crystals in passivated catalysts by conventional high-resolution transmission electron microscopy (HRTEM). By comparison with in situ HRTEM images obtained lately from similar catalysts, and with reference to recent density functional theory (DFT) calculations, we suggest that active B5-type sites on the surfaces of the ruthenium crystals are promoted by nearby promoter atoms via electrostatic interactions.
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References
A. Mittasch, US Patent 1,173,532 (1913).
K. Aika and A. Ozaki, J. Catal. 16 (1970) 97.
K. Aika, H. Hori and A. Ozaki, J. Catal. 27 (1972) 424.
R.M. Elofson and F.F. Gadallah, US Patent 4,142,993 (1979).
K. Aika and K. Tamaru, in: Ammonia: Catalysis and Manufacture, ed. A. Nielsen (Springer, Berlin, 1995), p. 103.
S.R. Tennison, in: Catalytic Ammonia Synthesis, ed. J.R. Jennings (Plenum Press, New York, 1991), p. 303.
L. Forni, D. Molinari, I. Rossetti and N. Pernicone, Appl. Catal. A. 185 (1999) 269.
Z. Kowalczyk, S. Jodzis, W. Raróg, J. Zieliński and J. Pielaszek, Appl. Catal. A 173 (1998) 153.
C.J.H. Jacobsen and S.E. Nielsen, Safety in Ammonia Plants and Related Facilities, AIChE, 2002.
Nitrogen & Methanol, May–June (2002) 34.
H. Bielawa, O. Hinrichsen, A. Birkner and M. Muhler, Angew. Chem. 40 (2001) 1061.
C.J.H. Jacobsen, J. Catal. 200 (2001) 1.
T.W. Hansen, J.B. Wagner, P.L. Hansen, S. Dahl and C.J.H. Jacobsen, Science 294 (2001) 1508.
S. Dahl, A. Logadottir, R.C. Egebjerg, J.H. Larsen, I. Chorkendorff, E. Törnqvist and J.K. Nørskov, Phys. Rev. Lett. 83 (1999) 1814.
S. Dahl, E. Törnqvist and I. Chorkendorff, J. Catal. 192 (2000) 381.
S. Dahl, J. Sehested, C.J.H. Jacobsen, E. Törnqvist and I. Chorkendorff, J. Catal. 192 (2000) 391.
S. Dahl, P.A. Taylor, E. Törnqvist and I. Chorkendorff, J. Catal. 178 (1998) 679.
N.D. Spencer, R.C. Spencer and G.A. Somorjai, J. Catal. 74 (1982) 129.
F. Bozso, G. Ertl and M. Weiss, J. Catal. 50 (1977) 519.
S. Dahl, E. Törnqvist and C.J.H. Jacobsen, J. Catal. 198 (2001) 97.
R. Van Hardeveld and A. Van Montfoort, Surf. Sci. 4 (1966) 396.
C.J.H. Jacobsen, S. Dahl, P.L. Hansen, E. Törnqvist, L. Jensen, H. Topsøe, D.V. Prip, P.B. Møenshaug and I. Chorkendorff, J. Mol. Catal. 163 (2000) 19.
A. Logadottir, T.H. Rod, J.K. Nørskov, B. Hammer, S. Dahl and C.J.H. Jacobsen, J. Catal. 197 (2001) 229.
S. Dahl, A. Logadottir, C.J.H. Jacobsen and J.K. Nørskov, Appl. Catal. A 222 (2001) 19.
J. Dohrup, C.J.H. Jacobsen and C. Olsen, European Patent Appl. 1,013,603 (2000).
B. Fastrup, Cat. Lett. 48 (1997) 111.
J. Sehested, C.J.H. Jacobsen, E. Törnqvist, S. Rokni and P. Stoltze, J. Catal. 188 (1999) 83.
R.F. Egerton, Electron Energy-loss in the Electron Microscope, 2nd ed. (Plenum Press, New York, 1996).
Z. Kowalczyk, S. Jodzis, W. Raróg, J. Zieliński, J. Pielaszek and A. Presz, Appl. Catal. A 184 (1999) 95.
D. Szmigiel, H. Bielawa, M. Kurtz, O. Hinrichsen, M. Muhler, W. Raróg, S. Jodzis, Z. Kowalszyk, L. Znak and J. Zielinski, J. Catal. 205 (2002) 205.
J.J. Mortensen, B. Hammer and J.K. Nørskov, Phys. Rev. Lett. 80 (1998) 4333.
J.J. Mortensen, B. Hammer and J.K. Nørskov, Surf. Sci. 414 (1998) 315.
S. Hagen, R. Barfod, R. Fehrmann, C.J.H. Jacobsen, H.T. Teunissen, K. Ståhl and I. Chorkendorff, Chem. Commun. (2002) 1206.
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Hansen, T.W., Hansen, P.L., Dahl, S. et al. Support Effect and Active Sites on Promoted Ruthenium Catalysts for Ammonia Synthesis. Catalysis Letters 84, 7–12 (2002). https://doi.org/10.1023/A:1021028718491
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DOI: https://doi.org/10.1023/A:1021028718491