Preparation and properties of anchored Pt-Mo/SiO2 bimetallic catalyst

Pt-Mo/SiO2 bimetallic catalysts of 3wt%Pt-1.1wt%Mo prepared by anchoring and impregnation techniques are examined and compared. TPR, ESR and TEM measurements and n-pentane conversion are used to characterize the surface properties and the catalytic behavior of different preparation respectively. The results clearly demonstrate the significant effect of preparation method. With anchoring technique, uniform surface species interpreted as Pt3Mo2(O-Si)2, is formed which is evenly distributed in the surface layer and responsible for the high hydrogenolysis activity of the resulted catalyst. For the impregnated preparation, the formation of such kind of stoichiometric surface complexes is almost completely excluded. The separate particles of platinum, molybdenum oxides and Pt-Mo alloys are the surface species which indicate a strong synergy effect in n-pentane hydrogenolysis. 7 refs.; 6 figs.; 2 tabs