Abstract
Electron spectroscopic data and reactor measurements show that electrochemical promotion (EP) of thin film catalysts deposited on solid electrolyte supports is the result of spillover phenomena at the three‐phase boundary between the electrolyte, the catalyst and the gas phase. Ions from the electrolyte are discharged at the electrode/electrolyte interface and migrate to cover the catalyst surface whose properties are thereby strongly altered. The EP effect and the phenomena that underlie it are illustrated here by reference to the Na‐promoted catalytic reduction of NO by CO over copper. Electro‐pumping of Na from a β″‐alumina solid electrolyte to the catalyst surface results in large improvements in both activity and selectivity of the latter. Under reaction conditions, the alkali promoter is present as submonolayer amounts of NaNO3 on an oxidised Cu surface. The results indicate that Cu0 sites are not of significance and that the catalytically active surface is dominated by Cu+ and Cu2+ sites. They also show that Cu+ is the critically important site for NO adsorption and that EP is due to Na‐induced enhancement of the adsorption and dissociation of NO at Cu+ sites.
Similar content being viewed by others
References
M.P. Kiskinova, Poisoning and Promotion in Catalysis Based on Surface Science Concepts and Experiments (Elsevier, Amsterdam, 1992).
J.W. Niemantsverdriet, Appl. Phys. A 61 (1995) 503.
S.J. Thomson, J. Chem. Soc., Faraday Trans. 83 (1987) 2001.
R.M. Ormerod and R.M. Lambert, in: Surface Reactions, Springer Series in Surface Science, Vol. 34, ed. R.J. Madix (Springer, Berlin, 1994) pp. 89–131.
A.F. Lee, C.J. Baddeley, C. Hardacre, R.M. Ormerod, R.M. Lambert, G. Schmid and H. West, J. Phys. Chem. 99 (1995) 6096.
I.V. Yentekakis, A. Palermo, N.C. Filkin, M.S. Tikhov and R.M. Lambert, J. Phys. Chem. B 101 (1997) 3759.
N.C. Filkin, M.S. Tikhov, A. Palermo and R.M. Lambert, J. Phys. Chem. A 103 (1999) 2680.
I.V. Yentekakis, R.M. Lambert, M.S. Tikhov, M. Konsolakis and V. Kiousis, J. Catal. 176 (1998) 82.
M. Konsolakis, A. Palermo, M. Tikhov, R.M. Lambert and Y.V. Yentekakis, Ionics 4 (1998) 148.
M. Konsolakis, L. Nalbantian, N. McLeod, I.V. Yentekakis and R.M. Lambert, Appl. Catal. B (1999), in press.
S. Tracey, A. Palermo, J.P. Holgado Vazquez and R.M. Lambert, J. Catal. 179 (1998) 231.
S. Wodiunig, F. Bokeloh, J. Nicole and Ch. Comninellis, Electrochem. Solid State Lett. 2 (1999), in press.
S. Bebelis and C.G. Vayenas, J. Catal. 118 (1989) 125.
C.G. Vayenas, M. Jaksic, S. Bebelis and Neophytides, in: Modern Aspects of Electrochemistry, eds. O'M Bockris, B.F. Conway and E. White (Plenum, New York, 1995) pp. 57–202.
C.G. Vayenas and S.G. Neophytides, in: Catalysis, Vol. 12 (Roy. Soc. Chem., Cambridge, 1996) pp. 195–253.
M. Makri, C.G. Vayenas, S. Bebelis, K.H. Besocke and C. Cavalca, Surf. Sci. 369 (1996) 351.
C. Pliangos, I.V. Yentekakis, X. Verykios and C.G. Vayenas, J. Catal. 154 (1995) 124.
I.V. Yentekakis and S. Bebelis, J. Catal. 137 (1992) 278.
Ch. Karavasilis, S. Bebelis and C.G. Vayenas, J. Catal. 160 (1994) 190.
I.V. Yentekakis, G.D. Moggridge, C.G. Vayenas and R.M. Lambert, J. Catal. 146 (1994) 292.
O.A. Marina, I.V. Yentekakis, C.G. Vayenas, A. Palermo and R.M. Lambert, J. Catal. 166 (1997) 218.
R.M. Lambert, M. Tikhov, A. Palermo, I.V. Yentekakis and C.G. Vayenas, Ionics 5 (1995) 366.
A. Palermo, R.M. Lambert, I.R. Harkness, I.V. Yentekakis, O. Marina and C.G. Vayenas, J. Catal. 161 (1996) 471.
I.V. Yentekakis and C.G. Vayenas, J. Catal. 149 (1994) 238.
T.I. Politova, V.A. Sobyanin and V.D. Belyaev, React. Kinet. Catal. Lett. 41 (1990) 321.
M. Marwood and C.G. Vayenas, J. Catal. 178 (1998) 429.
R.D. Armstrong and M. Todd, in: Solid State Electrochemistry, ed. P.G. Bruce (Cambridge University Press, Cambridge, 1995) p. 277.
F.J. Williams, M.S. Tikhov, A. Palermo and R.M. Lambert, in preparation.
V.I. Parvulescu, P. Grange and B. Delmon, Catal. Today 46 (1998) 233.
J.W. London and A.T. Bell, J. Catal. 31 (1973) 96.
F.H.M. Dekker, S. Kraneveld, A. Bliek, F. Kapteijn and J.A. Moulijn, J. Catal. 170 (1997) 168.
M. Fernandez-Garcia, C. Marquez Alvarez, I. Rodriguez-Ramos, A. Guerrero-Ruiz and G.L. Haller, J. Phys. Chem. 99 (1995) 16380.
A. Palermo, R.M. Lambert, I.R. Harkness, I.V. Yentekakis, O. Marina and C.G. Vayenas, J. Catal. 161 (1996) 471.
N.D. Lang, S. Holloway and J.K. Norskov, Surf. Sci. 150 (1985) 24.
F. Parmigiani, G. Pachioni, F. Illas and P.S. Bagus, J. Electron Spectrosc. Relat. Phenom. 59 (1992) 255.
H.C. Allen, J.M. Laux, R. Vogt, B.J. Finlayson-Pitts and J.C. Hemminger, J. Phys. Chem. 100 (1996) 6371.
J.J. Yeh and I. Lindau, Atomic Data and Nuclear Data Tables, 32 (1985) p. 1.
C.D. Wagner, in: Practical Surface Analysis by Auger and X-ray Photoelectron Spectroscopy, eds. D. Briggs and M.P. Seah (Wiley, New York, 1983).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Lambert, R.M., Williams, F., Palermo, A. et al. Modelling alkali promotion in heterogeneous catalysis: in situ electrochemical control of catalytic reactions. Topics in Catalysis 13, 91–98 (2000). https://doi.org/10.1023/A:1009076720641
Issue Date:
DOI: https://doi.org/10.1023/A:1009076720641