HYDROTREATING OF PETROLEUM RESIDUES WITH DISPERSED CATALYSTS DERIVED FROM THIOMOLYBDATES AND MOLYBDENYL ACETYLACETONATE

The effect of the catalyst precursor formulation on the hydrotreatment of Belayim atmospheric residue was investigated and different Q(2)[MoxSy] complexes were tested. The effect of the counterion Q and of the y/x ratio were examined; the most interesting results were obtained for S/Mo less than or equal to 4 with [Mo3S9](2-) as the best precursor and with phosphonium salts as the best counterions. Phosphorus promotion might be related to vanadium demetallation. These results were compared with those obtained by using MoO2(acac)(2) (acac = acetylacetonate) as the catalyst precursor. In order to discriminate between thermic and catalytic aspects, the effect of catalyst concentration was carefully examined; the higher the concentration, the higher the removal of heteroatoms from the residue without producing too many light products.