An EXAFS study on the so-called "Co-Mo-S" phase in Co/C and CoMo/c, compared with a Mössbauer emission spectroscopy study

EXAFS measurements were performed on four sulfided catalysts with the same compn. as their 57Co-contg. counterparts which were previously characterized by Moessbauer emission spectroscopy. The Co species in Co/C catalysts with a Co-Mo-S-like Moessbauer emission spectrum after sulfidation at 373 K is similar to the species with the Co-Mo-S spectrum in CoMo/C catalysts. In both cases the Co atoms are present in a very highly dispersed Co species. In the catalyst without Mo this sulfidic Co species strongly sinters during sulfidation at 673 K, resulting in a Co9S8-type phase. In the CoMo/C catalyst, the Mo hinders sintering of the Co species. [on SciFinder (R)]