Abstract: To study the effect of support surface properties on the dispersion of metal species and hydrodesulfurization performance, ammonium metatungstate and tunstophosphoric acid were loaded on Al2O3 and F-Al2O3, respectively,to prepare corresponding catalysts. The samples were characterized by XRD, IR, N2 physisorption, XPS and TEM techniques. The characterization results showed that fluorine modification notably decreased the amounts of hydroxyl groups on alumina support and lowered the isoelectric point of support; compared with that of ammonium metatungstate solution, the pH value of tunstophosphoric acid solution was lower, which favors the adsorption of tunstophosphoric acid anions on the support. On the oxidic or sulfided catalysts, the presence of closely-bonded and well-dispersed tungsten species on support impeded the formation of (pseudo-) boehmite under hydrothermal conditions, but could not avoid the formation of aluminum fluoride by reaction of fluoride and alumina. The catalyst prepared by matching tunstophosphoric acid and F-Al2O3 exhibited better HDS activity for 4, 6-DMDBT than the other catalysts, due to higher degree of W sul?dation and more shorter WS2 slabs with proper stacking number.

Key words: Fluorine, alumina, ammonium metatungstate, phosphotungstic acid, adsorption, dispersion, tungsten disulfide, hydrodesulfurization