Electrochemical promotion of ammonia decomposition over Fe catalyst films interfaced with K+- & H+- conductors
- 95 Downloads
The electrochemical promotion of the ammonia decomposition reaction over Fe catalyst films interfaced with K2YZr(PO4)3, a K+-conductor, and CaZr0.9In0.1O3−a, a H+-conductor, was investigated at temperatures 500–600 °C. At the higher temperatures, the catalytic rate was found to decrease significantly and reversibly upon decreasing the catalyst potential, VWR, i.e., upon pumping K+ or H+ to the Fe surface. The effect of potassium was more pronounced than that of protons leading to almost complete poisoning of the reaction. At the lower temperatures, it was found that electrochemical supply of moderate amounts of potassium causes an enhancement in the catalytic rate while higher amounts poison the reaction.
The study reports, for the first time, electrochemical promotion over a Fe catalyst and shows that K+-conductors can also be used to induce the effect of Non-Faradaic Electrochemical Modification of Catalytic Activity (NEMCA). The effect of backspillover potassium ions and protons on the catalytic activity is discussed in terms of the theory of electrochemical promotion by considering the effect of varying catalyst work function on the coverages and chemisorptive bond strengths of NH3, N and H. The results show the possibility of using electrically promoted catalyst pellets to alter the performance of industrial reactions.
KeywordsCatalytic Activity Catalytic Rate Catalyst Potential Industrial Reaction Electrochemical Promotion
Unable to display preview. Download preview PDF.
- C.G. Vayenas, M.M. Jaksic, S. Bebelis and S. Neophytides, in: Modern Aspects of Electrochemistry,No 29, (J.O 'M. Bockris, B.E. Conway and R.E. White, Eds) Plenum Press, New York, 1996) pp. 57–202 and references therein.Google Scholar
- B. Crzybowska-Swierkosz and J. Haber in Annual Reports on the Progress of Chemistry, Vol.91 (The Royal Society of Chemistry, Cambridge, U.K., 1994) pp. 395–439Google Scholar
- P.D. Petrolekas, S. Brosda and C.G. Vayenas, J. Electrochem. Soc., in press.Google Scholar
- M. Makri, A. Buekenhoudt, J. Luyten and C.G. Vayenas, Ionics2, 282 (1996).Google Scholar
- S. Neophytides, D. Tsiplakides, O. Enea, M.M. Jaksic and C.G. Vayenas, J. Electrochem. Soc. (in press).Google Scholar
- P.D. Petrolekas, S. Balomenou and C.G. Vayenas, J. Electrochem. Soc., submitted.Google Scholar
- U. Guth, S. Brosda, B. Loescher, A. Simmich, P. Schmidt, H.-H. Möbius, Material Science Forum76, 137 (1991).Google Scholar
- Ch. Karavasilis, S. Bebelis, and C.G. Vayenas, J. Catal.160, 205 (1996).Google Scholar
- W. Zipprich, H.-D. Wiemhöfer, K. Vohrer, and, W. Göpel, Ber. Bunsenges. Phys. Chem.99, 1406 (1995).Google Scholar
- Z. Kowalcyk, J. Sentek, S. Jodzis, M. Muhler and O. Hinrichsen, J. Catal.169, 407 (1997) and references therein.Google Scholar