ESR study on the stability of dithiomolybdate and -tungstate in the presence of H/sub 2/S

The resistance of Mo(W) oxo-sulfo compounds against sulfiding to MoS/sub 2/(WS/sub 2/) was investigated by electron spin resonance (ESR) studies of (NH/sub 4/)/sub 2/MoO/sub 2/S/sub 2/ and (NH/sub 4/)/sub 2/WO/sub 2/S/sub 2/ after treatment of the compounds with H/sub 2/S/He mixtures at various temperatures. The results indicated that dithiomolybdate and dithiotungstate anions are transformed into metal sulfides. The H/sub 2/S acted as a reducing agent. An ESR signal that can be ascribed to oxo-sulfo species was not observed when supported real catalysts were treated with H/sub 2/S/He mixtures. (BLM)