Electrochemical promotion of ammonia decomposition over Fe catalyst films interfaced with K⁺- & H⁺- conductors

Abstract

The electrochemical promotion of the ammonia decomposition reaction over Fe catalyst films interfaced with K₂YZr(PO₄)₃, a K⁺-conductor, and CaZr_0.9In_0.1O_3−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, V_WR, 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.