Reactions of n-hexane and methylcyclopentane on alumina-supported platinum–rhenium catalysts

Abstract

Reactions with excess hydrogen of n-hexane and of methylcyclopentane at 550 K have been studied in a static reactor system on a series of platinum–rhenium catalysts containing 0.5% metal by weight. The various reactions which took place have been grouped into two main categories according to the pattern of activity found across the series of catalysts. (1) Ring opening of methylcyclopentane, and the minor process of its demethanation, and 1,5 cyclization of n-hexane occurred readily over platinum but activity decreased steadily with increase of rhenium content and was low for pure rhenium. (2) Skeletal isomerization of n-hexane, ring enlargement of methylcyclopentane and general hydrogenolysis (more important with n-hexane than with methylcyclopentane) were catalysed most effectively by catalysts with about equal amounts of the two metals and less rapidly on the platinum-rich or rhenium-rich catalysts. It is suggested that the first category of reactions involves either 1,5 or 1,2 adsorbed hydrocarbon species whereas the second category is dependent on the formation of 1,3 adsorbed species.