So-called “Co-Mo-S” phase observed in carbon-supported Co and Co-Mo sulfide catalysts by Mössbauer emission spectroscopy

Research paper by A. M. Van Der Kraan, M. W. J. Crajé, E. Gerkema, W. L. T. M. Ramselaar, V. H. I. De Beer

Indexed on: 01 Mar '89Published on: 01 Mar '89Published in: Hyperfine Interactions


In-situ Mössbauer Emission Spectroscopy (MES) has been used to study the type of phases present in sulfided activated carbon-supported Co and Co-Mo hydrodesulfurization (HDS) catalysts. Most of the reported MES studies are performed on Co-Mo/Al2O3 catalysts. Co species in the so-called “Co-Mo-S” phase, sofar only observed in sulfided catalysts containing Co and Mo, should govern the HDS activity. The present observations show that the same Co species in sulfided Co/C and Co-Mo/C catalysts, with the same quadrupole splitting as “Co-Mo-S” can be formed. Furthermore, it turns out that the QS-value of the “active phase” in the sulfided Co/C and Co-Mo/C catalysts depends on the sulfiding temperature and Co content. Hence, it seems unlikely that there will be only one well defined active sulfide phase which governs the HDS activity.