La2Ce2O7 supported ruthenium as a robust catalyst for ammonia synthesis

La 2 Ce 2 O 7 nanoparticles were prepared by citric acid complexation method followed by calcination at varied temperatures. Then, supported with 4 wt% Ru, they were evaluated as the catalysts for ammonia synthesis under conditions similar with industry. With La 2 Ce 2 O 7 being calcinated at 700 or 800 °C, the experimental results indicate that the Ru/La 2 Ce 2 O 7 catalyst exhibits much higher ammonia concentration or ammonia synthesis rate than that of Ru/CeO 2 and Ru/La 2 O 3 . In addition, Ru/La 2 Ce 2 O 7 possesses high stability under over-heating test. In the absence of any promotor, ammonia concentration of Ru/La 2 Ce 2 O 7 catalyst approaches 14% at 450 °C, GHSV of 10000 h −1 and pressure of 10 MPa. The rate-determining step of ammonia synthesis, dissociation of N 2 is significantly facilitated by the strong metal–support interaction (SMSI) between Ru and La 2 Ce 2 O 7 . Due to the interaction, La 2 Ce 2 O 7 tends to donate electrons to Ru, resulting in the high electron density over the surface of Ru active sites which is favorable for the dissociation of N 2 . Consequently, high activity is achieved.