with a Mossbauer Emission Spectroscopy Study

EXAFS measurements were performed on four sulfided catalysts with the same composition as their 57Co-containing counterparts which were previously characterized by Mossbauer emission spectroscopy. It was shown that the Co species in Co(373)/C catalysts with a “Co-Mo-S”-like Mossbauer 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 Co9S,-type phase. In the CoMo/C catalyst, the Mo hinders sintering of the Co species