Selective ring-opening of methylcyclopentane on platinum-based bimetallic catalysts Original Research Article

Several monometallic catalysts supported on alumina were tested in methylcyclopentane ring-opening under pressure. Among the monometallic catalysts tested (Ru, Re, Rh, Pt and Ir), iridium and rhodium catalysts were the most active but iridium was by far the most selective in ring-opening (RO) products (2-methylpentane, 3-methylpentane and n-hexane), the formation of C1–C5 products being negligible, as already reported in the literature. Thereafter, platinum-based bimetallic catalysts supported on alumina were prepared by redox surface reaction in order to favor the metal–metal interaction. The aim was to obtain bimetallic catalysts leading to selectivity towards RO products similar to that of the iridium catalyst. Two types of modifiers were studied, namely (i) inactive species such as copper and germanium and (ii) active promoters for hydrogenolysis reactions, such as ruthenium and rhodium. It was shown that with inactive metals, the parent platinum catalyst undergoes mainly a dilution of its active phase. An increase of the activity is observed for the Pt-Ru/Al2O3 systems compared to the parent one, but also an increase of the C1–C5 products. On the contrary, the addition of Rh allowed us to increase the activity of the platinum parent catalyst and to obtain bimetallic catalysts with selectivity towards RO products similar to that obtained with iridium in same conditions.