Investigation on catalytic performance and desorption behaviors of ruthenium catalysts supported on rare-earth oxides for NH3 decomposition

The basic property of the catalyst can influence the catalytic performance for the NH3 decomposition by alleviating associative desorption of N atom, known as a rate-determining step (RDS) in the Ru-based catalysts, but there were few experimental data to prove the alleviation of this step. Therefore, the Ru catalyst supported on rare-earth oxides and zirconium oxide were synthesized to compare the catalytic performance for NH3 decomposition and its dependence on the basic property of the Ru catalysts, including the other characterizations. The catalytic activities at 500 °C decreased in order of Ru/La2O3 > Ru/PrxOy > Ru/Sm2O3 ≅ Ru/Gd2O3 > Ru/Y2O3 > Ru/Yb2O3 > Ru/ZrO2 catalysts. This catalytic activity was related to the basic strength of the catalysts, which can influence the electron state of the impregnated Ru particles. The enhanced basic strength could modify the electronic state of the Ru particles on the support owing to electron donation from the oxide support to the Ru particles, and NH3-temperature programmed surface reaction (NH3-TPSR) confirmed that this enhanced electron donation could promote the desorption step of N atoms.