Characterisation of Ru/C catalysts for ammonia synthesis by oxygen chemisorption Original Research Article

A standard chemisorption procedure has been set up for the determination of Ru dispersion in Ru/C catalysts. Pulse chemisorption of oxygen was carried out at 0 °C, after having proved that no corrosive chemisorption phenomena are present. An average chemisorption stoichiometry Ru∗/O=1.0 was experimentally determined through measurements on Ru black. The procedure was applied to the investigation of promoted and unpromoted Ru/C catalysts for ammonia synthesis, supported on two different carbon supports. The main factor influencing Ru dispersion showed to be Ru loading, while the addition of even large amounts of Ba–Cs–K promoters has practically no influence. It is also briefly discussed how such results can help in elucidating several aspects of the behaviour of Ru/C as catalyst for ammonia synthesis.