Additive effect of alkaline earth metal on hydrogen production via catalytic ammonia decomposition over Co/CeO2 catalysts

The production of hydrogen from directly catalytic ammonia decomposition shows promise in improving the ammonia viability for engine use. For practical application, it is demanded to investigate additives as well as their impact mechanism on the catalytic properties of transition metal catalysts. Herein, a series of Co/CeO₂ catalysts were prepared via a facile precipitation method and the effect of Mg adding was investigated. It is found that addition of 1% Mg decreased the catalytic activity of 5% and 10% Co/CeO₂, while increased that of 20% Co/CeO₂. Systematic characterizations revealed that Mg promoted the metal-support interaction, which not only benefited the dispersion of Co, but also increased the valence state of Co and enhanced the reducibility. Also, more oxygen vacancies were generated, thus benefiting the reaction process. This work invested new insights into the role of alkaline-earth metal in NH₃ decomposition and provided a strategy to modulate the hydrogen–ammonia ratio which is vital for NH₃ combustion.