Sono-synthesis and characterization of nanophase hydrodesulfurization catalysts

A convenient synthesis of nano-size HDS catalytic materials in several-gram quantities is the main focus at Brookhaven National Laboratory (BNL) and Argonne National Laboratory (ANL). Several hydrocarbon solvents were evaluated to optimize "cavitation" that is critical to produce nano Mo metal particles by decomposition of molybdenum hexacarbonyl. Further in situ complexation of nano Mo with elemental sulfur yielded nano MoS₂. With a known ratio of Co₂(CO)₈/Mo(CO)₆, the method produced nano Co/MoS₂. Sonolysis of Mo(CO)₆ in the presence of γ-Al₂O₃ produced supported nano Mo. The yields of all three nano-sized materials were > 90% based on the starting Mo(CO)₆. The activity of the unsupported nanosized catalysts, however, was much higher than the commercial micron-sized counterparts. In the micron-sized catalysts, diffusion in between the long rafts of MoS₂ was mass transport limited, so it was expected that most of the activity came from the "rims" and "edges". Incorporation of Co to MoS₂ increased the activity of the catalyst. To model these olefins in HDS runs, 1-octene (1 wt %) was added to the liquid feed and the HDS tests were run again. The sonochemically synthesized nanophase catalysts were less active for olefin hydrogenation than their commercial counterparts.