Influence of the activation conditions of bimetallic catalysts NM–Mo/γ-Al2O3 (NM=Pt, Pd and Ru) on the activity in HDT reactions Original Research Article

Monometallic noble metal sulfide and bimetallic noble metal molybdenum (NM–Mo, NM=Pt, Ru, Pd) supported on γ-alumina were prepared by wet impregnation of gamma-alumina or MoS2 (10 wt.% Mo)/γ-Al2O3 with an aqueous solution of the corresponding salt. Three different sulfiding agents were used in order to look for their influence on the catalytic performance. The catalysts were characterized by temperature-programmed reduction and evaluated in simultaneous HDS of dibenzothiophene and HYD of naphthalene reactions. Results show that HDS activity of PtMo/γ-Al2O3 (0.5 wt.% Pt) catalyst, sulfided with H2S (15 vol%)/N2, is comparable to that of the traditional CoMo (3 wt.% CoO) and two times higher for HYD activity. A synergetic effect was detected when PtMo/γ-Al2O3 and RuMo/γ-Al2O3 catalysts were used. Synergy is high for PtMo/γ-Al2O3 catalyst in HDS and high in HYD for RuMo/γ-Al2O3 catalyst. TPR experiments indicate that both noble metal nature and sulfiding agent have a noticeable influence on the reducibility of the molybdenum sulfide phase and, therefore, on the catalytic activity.