Ceria-Zirconia-Supported Ruthenium Catalysts for Hydrogen Production by Ammonia Decomposition

Commercial cerium-zirconium oxide supports (Ce0.5Zr0.5O2, Ce0.75Zr0.25O2, and Ce0.4Zr0.5Y0.05La0.05O2) were used to prepare Ru/CeZrOx catalysts. According to the XRD and IR spectroscopy data, the supports consist of ceria-based substitutional solid solutions. The specific surface areas of supports and catalysts are similar and range from 71-89 m(2)/g. As shown by TEM and XRD methods, the size of support particles equals 6-11 nm. According to the TEM data, the size of ruthenium particles does not exceed 1.3 nm. The catalyst activity in the ammonia decomposition process was studied. The Ru/Ce0.75Zr0.25O2 catalyst at temperature 500 degrees C and GHSV 120,000 h(-1) demonstrated the highest hydrogen productivity of 53.3 mmol H-2/(g(cat)center dot min) and compares well with the best results reported in the literature. The kinetics of ammonia decomposition reaction were calculated using the Temkin-Pyzhov exponential expression. The developed mathematical model well described the experimental data. The studied catalysts demonstrated high activity for the ammonia decomposition reaction.