IDENTIFICATION OF NEW HYDROGEN SPECIES ADSORBED ON RUTHENIUM SULFIDE BY NEUTRON SPECTROSCOPY

Inelastic neutron scattering (INS) has been used to study the adsorption of hydrogen on a partially desulfurized ruthenium sulfide catalyst. Different hydrogen species have been evidenced by changing the experimental conditions (temperature and hydrogen coverage), by contrast to previous neutron studies which reported only SH groups. When RuS2 is partially desulfurized, new vibrational peaks are found at 540 and 823 cm-1. These peaks are assigned to the bending modes of two different RuH linear species. The hydridic groups, which are the active species in hydrogenation reactions, are more weakly adsorbed than the acidic groups; their relative proportion is derived from the INS spectra and discussed in relation with TPD measurements.