Mössbauer emission study on 57Co doped carbon-supported Ni and Ni-Mo sulfide hydrotreating catalysts : the influence of phosphorus on the structure

In the present study it is demonstrated that Mössbauer emission spectroscopy (MES) can generate information on the various Ni phases present in sulfided Ni containing catalysts when a small amount of 57Co is used as a probe for Ni.Application of MES to 57Co:Ni(4.5)Mo(8.0)/C and 57Co:Ni(5.6)/C revealed the formation of a so-called "Ni-Mo-S" phase in the former and a bulk sulfide in the latter catalyst. After addition of phosphorus a "Ni-(thio)phosphate" phase is found to be formed in both catalysts.The relation between the structure of these catalysts and their activity for thiophene HDS and quinoline HDN is discussed