-Catalytic properties of silica-supported heteropolyacids (HPA) in a mechanical mixture with reduced Me-Ce oxides (Me=Ni, Pd) in n-hexane isomerization are studied. The role of each component of the mixed oxides (Ce and, typically Ni and Pd) ,and their optimum content were enlightened; cerium, not only is beneficial for eliminating or prevent, the coke deposition but is also effective for maintaining the Keggin structure of the highly-organized HPA during the reaction and, probably allows a better dispersion of the second metal species. Nickel and palladium, present as Ni 0 and Pd 0 reinforce the activation of the alkane which is difficult to obtain by directly attacking by an acid and, thus, enhance noticeably the activity of the catalyst. The best mechanical mixtures are obtained with 30-70 wt % NiCeO-HPW/SiO 2 and 50-50 wt % Pd 0.1 CeO-HPW/SiO 2 .These mixtures have the highest efficiency for a Ni/Ni+W atomic ratio of 0.66 and a Pd/Pd+W ratio of 0.40 respectively. At last the conversion of n-hexane is in the order: HPW>HSiW>HBW which seems consistent with the order of their acid strength as claimed in the literature, but the isomerization selectivity appears slightly higher on HSiW.
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