Selective oxidation of ammonia over Ru(0 0 0 1)

The decomposition and oxidation of NH3 have been studied on the Ru(0 0 0 1) surface in the temperature range from 150 up to 800 K. The results were compared to those found for Ir(1 1 0) and Ir(5 1 0). TDS results showed that most of the ammonia is dissociatively adsorbed between 150 and 300 K, with formation of H2 around 300 K and N2 between 600 and 800 K. N2 desorption shifts to lower temperatures with increasing surface oxygen coverage. The products of ammonia oxidation observed were N2, H2O and N2O. Formation of NO was not found. Inhibition of the reaction presumably by N species was observed until 450 and 670 K, depending on the NH3/O2 ratios. Above those temperatures the reaction started as manifested by a decrease in the NH3 and O2 pressures and a simultaneous increase in the H2O, N2 and N2O pressures.