Electrochemical activation of Ru catalyst with alkaline ion conductors for the catalytic decomposition of ammonia

Abstract

• Ammonia decomposition on Ru catalyst is electrochemically activated with Na and K. • The promotion effect is higher with K than Na. • The promotion is due to a strengthening of the bond of weakly adsorbed N species. • Under optimal conditions the hydrogen production rate increased above 230% • The EPOC effect allows catalyst activation at low temperatures. This study reports the electrochemical activation (EPOC) of ruthenium catalyst film with alkaline ion conductors for hydrogen production via catalytic decomposition of ammonia. Two electrocatalysts, Ru/Na-βAl 2 O 3 and Ru/K-βAl 2 O 3 have been prepared, characterized, and tested under low temperature reaction conditions (250–350 °C). The electrochemically supply of moderate amounts of alkaline ions (Na + and K + ) from the solid electrolyte support to the ruthenium catalyst film, activated the hydrogen production rate. The promotional effect has been attributed to a strengthening of the chemisorptive bond of weakly adsorbed N surface species, which stabilizes N adsorbed molecules on the ruthenium catalyst surface and thus facilitating the ammonia decomposition reaction. Among the two alkali ions, the effect of potassium was stronger, increasing the hydrogen production rate above 230% at 300 °C under optimally conditions. Temperature programmed reaction experiments also confirms the interest of EPOC for the activation of the catalyst at low temperatures.