The effect of platinum modification by alloying and sulfur on the hydrogenolysis and aromatization of methylcyclopentane

Abstract

The reactions of methylcyclopentane (MCP) and hydrogen have been studied with various mono- and bi-metallic supported platinum and iridium catalysts. The effects of particle size (platinum), temperature, support and the size of ensembles of platinum or iridium atoms play significant roles in the mode of ring-opening of MCP. When acidic sites are present, the conversion of MCP is governed by the metal ensemble size. Sulfided (diluted) platinum catalysts resemble small particle platinum catalysts in the ring-opening of MCP, whereas sulfided (highly diluted) platinum-rhenium (or platinum-cobalt) catalysts show a shift from metal-catalysed to acid-catalysed reactions. The highly diluted systems have a very high selectivity to benzene at relatively high temperatures, whereas at lower temperatures the formation of cyclohexane prevails. With respect to the conversion to n-hexane two different pathways can be distinguished, one purely metallic and one which is bifunctional in character.