Selective ring-opening of methylcyclopentane on platinum-based bimetallic catalysts

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.

The aim of this study was to obtain platinum-based bimetallic catalysts leading to selectivity towards ring-opening (RO) products under pressure similar to that of the best monometallic iridium catalyst during methylcyclopentane (MCP) conversion. Similarly to Ir/Al2O3, and contrary to Pt/Al2O3 and Rh/Al2O3, Pt-Rh/Al2O3 catalysts are able to convert MCP selectively to RO products up to high MCP conversions.Figure optionsDownload as PowerPoint slide