RESIDUAL OIL HYDRODESULFURIZATION USING DISPERSED CATALYSTS IN A CARBON-PACKED TRICKLE-BED FLOW REACTOR

Heavy oil hydrodesulfurization (HDS) was carried out using dispersed c atalyst which deactivated less strongly than the conventional supporte d catalyst. Various kinds of transition-metal compounds containing eit her molybdenum, tungsten, nickel, or cobalt were tested as dispersed c atalyst precursors individually or in combination. Experiments were pe rformed in a continuous trickle bed reactor under high hydrogen pressu re for the feedstock of atmospheric residual oil. To recover dispersed catalysts from the reactant mixture, activated carbon was packed into the reactor on which the dispered catalytic species happened to be de posited. Of the catalytic precursors examined, the compound containing molybdenum showed the highest conversions for sulfur and asphaltenes. A large HDS activity synergism was observed for the combined catalyst system consisted of two precursors of different metal kind. The Go-Mo catalyst showed the highest activity and selectivity for HDS reaction . Selectivity for hydrocracking reaction was the highest with the Ni-M o catalyst. The Ni-W system showed the lowest activity in most of reac tions. Go-Mo was considered as the most promising dispersed catalyst s ystem for the HDS of heavy oil. It was proved that active carbon packe d in the reactor was very effective in recovering the dispersed cataly sts from reactant oils and that the dispersed catalysts deposited on a ctivated carbon were also catalytically active, resulting in higher yi eld particularly for HDS.