Effect of catalyst preparation method on ammonia decomposition reaction over Ru/MgO catalyst

NH₃ decomposition on Ru/MgO nanoparticles was strongly influenced by the pore structure of the MgO support. Specifically, MgO-supported Ru nanoparticles prepared from Ru hydroxide and hydromagnesite as catalyst precursors via deposition-precipitation (DP) and coprecipitation (CPT) methods exhibited high catalytic activity for NH₃ decomposition. The mesopores of MgO of about 3-5 nm and highly dispersed Ru species improved the catalytic performance. The electronic modification of metal species by alkali promoter facilitated the recombinative desorption of H and N atoms. However, no high electron density of Ru species was detected by XPS measurements, suggesting that the enhancement of the NH₃ decomposition activity by the preparation method was not due to the modification of the Ru electronic state but the improvement of the Ru dispersion. The reason for the high activity of the DP and CPT catalysts was both the effect of the diffusion of H₂ by the mesopores and improvement of Ru dispersion.