PREPARATION OF MOLYBDENUM-BASED CATALYSTS BY NEW SLURRY IMPREGNATION METHOD - ACTIVE-CARBON SUPPORTED MOLYBDENUM SULFIDE HYDRODESULFURIZATION CATALYST

Active carbon supported molybdena catalysts (15% MoO3) were prepared b y new slurry impregnation method (SIM) using carbon of various origin and particle size. The support was refluxed with the slurry of powdere d MoO3 in water. A low solubility of MoO3 was sufficient for transport of MoO3 from the powder via the solution to the surface of the suppor t. Calcination was left out because no other chemicals beside MoO3 and water were used in the impregnation. The catalysts were presulfided a nd tested in hydrodesulfurization of thiophene at 1.6 MPa and 300-400- degrees-C. Their activity was four times higher than that of a commerc ial molybdena on alumina catalyst and about the same as the activity o f a carbon supported catalyst prepared by the conventional impregnatio n method (CIM) using ammonium heptamolybdate. The advantage of the new SIM over CIM method is: (i) all molybdena species are deposited by ad sorption; precipitation during drying is negligible, (ii) oxidative de gradation of the carbon support cannot occur during preparation becaus e calcination is left out; ammonium sulfide is not formed during presu lfidation of the uncalcined catalysts.