Hydrogenolysis of methylcyclopentane and isomerization of 2-methylpentane over well characterized silica-supported platinum-ruthenium catalysts Original Research Article

The hydrogenolysis of methylcyclopentane and the isomerization of 2-methylpentane were studied over Pt-Ru bimetallic catalysts prepared using either H2PtCl6 and RuCl3 (Series A) or from Pt(NH3)4(NO3)2 and Ru(NH3)6Cl3 (series B). Energy-dispersive X-ray spectroscopy (EDXS) studies showed that the catalysts prepared using the amine precursors were 100% bimetallic. Image defocussing studies suggest that approximately 20% of the particles prepared using the chloride precursors were monometallic. At temperatures at which only ruthenium is active (413 K), the formation of C1 to C5 products was depressed over Pt-Ru bimetallic clusters. Tertiary-secondary carbon-carbon bond cleavage approaches that observed for ruthenium while secondary-secondary carbon-carbon bond cleavage is closer to that observed for platinum. The isomerization of 2MP at 493 K is representative of Pt-Ru activated dual sites since platinum is inactive at this temperature and ruthenium leads to extensive degradation of the molecule. The contribution of the cyclic mechanism was obtained using 13C labelled species. A synergistic effect was observed for the catalysts prepared using amine precursors. This is explained by considering an increase in the number of Pt-Ru dual surface sites.